Dror Paley and Shawn C. Standard
DEFINITION
The term proximal focal femoral deficiency (PFFD) is used to describe congenital femoral deficiency and deformity of the proximal femur to be distinguished from the congenital short femur.6 However, the more comprehensive term congenital femoral deficiency (CFD)13 better describes the spectrum of deficiency, deformity, and discrepancy ranging from the congenital short femur to the most severe PFFD.
The severity of the deformity varies widely, and this condition can be diagnosed in the prenatal period using ultrasound examination.11
In most cases, CFD is not simple coxa vara. Patients with CFD lack integrity, stability, and mobility of the hip and knee, with concurrent joint malorientation, bony deformity, and soft tissue contractures. The affected limb grows at an inhibited rate depending on the severity of the underlying deficiency. The resulting limb-length discrepancy (LLD) can be accurately predicted using the multiplier method.1,2,10
ANATOMY
Although existing classification systems for PFFD are descriptive, these classification systems are not helpful in determining the final femoral morphology or treatment strategies.13
The Paley classification system (FIG 1) is based on factors that reflect the severity of pathology and reconstructability of the congenitally deficient femur. This classification is based on pathologic factors that determine surgical reconstruction strategies.8
The abnormal anatomy of CFD consists of coxa vara of the proximal femur with abduction contracture of the hip (ie, tensor fascia lata [TFL], gluteus medius, and gluteus minimis muscles), proximal femoral extension deformity (flexion in some cases) with concurrent hip flexion contracture (ie, rectus femoris, TFL, and psoas muscles), and external femoral torsion–retroversion with concurrent external soft tissue contracture (ie, piriformis muscle).
The proximal femur can also present a region of delayed ossification in either the subtrochanteric region or the neck region. Ossification of the cartilaginous proximal femur differentiates Paley type 1a CFD (ie, normal ossification) from Paley type 1b CFD (ie, delayed ossification) (FIG 1).
Once treated with realignment of the proximal femur, these regions of delayed ossification in the type 1b hip begin to ossify (the regions do not always fully unite), converting the hip into type 1a. This area of delayed ossification is often mistaken for a pseudarthrosis (it could be referred to as a stiff cartilaginous pseudarthrosis to differentiate it from type 2, in which there is a true mobile, fibrous pseudarthrosis).
A more severe form of CFD is classified as Paley type 2; this type has a true mobile pseudarthrosis between the greater trochanter and femoral head or complete absence of the femoral head (FIG 1).
The most severe proximal deficiencies are classified as Paley type 3 (diaphyseal deficiencies). In these cases, the greater trochanter is absent and the knee joint is affected to a greater (range of motion [ROM] less than 45 degrees) or lesser (ROM more than 45 degrees) extent. Complete absence of the femur is included in this group.
In very rare cases, there is a distal deficiency of the femur (ie, Paley type 4). Cases of distal deficiency present with very severe knee varus but a well-developed, intact hip joint.
Acetabular dysplasia is almost always present in patients with CFD. This deformity must be recognized and corrected to prevent subluxation or dislocation of the hip during lengthening.
Congenital knee abnormalities also exist with CFD. Absent or hypoplastic cruciate ligaments (ie, anterior cruciate ligament [ACL], posterior cruciate ligament [PCL]), hypoplastic lateral femoral condyle resulting in genu valgum, and hypoplastic patella with lateral maltracking, subluxation, or dislocation are common. Rotatory instability of the tibiofemoral joint and knee flexion contractures (ie, biceps femoris muscle, posterior knee joint capsule, iliotibial band) are also common.
PATHOGENESIS
The cause of an isolated single-limb abnormality is usually unknown. CFD is usually not related to a genetic syndrome. This is in contrast to radial clubhand, tibial hemimelia, or multiple limb deficiencies.
A patient with CFD presenting for initial evaluation does not require a genetic consultation unless multiple limb deficiencies or other congenital malformations are present.
NATURAL HISTORY
The natural history of CFD is a progressive LLD in unilateral cases. The deformities and soft tissue contractures described above persist but do not progress.
The Paley type 1b hip shows eventual ossification of the cartilaginous femoral neck or subtrochanteric region. Although ossification occurs over time, the severe coxa vara deformity persists.
Progressive LLD can be accurately predicted using the multiplier method.1,2,10 Determining the LLD at maturity and using the Paley classification system allows the surgeon to formulate an overall strategy for deformity correction and limb lengthening.
The number and timing of surgical procedures can be presented as a general overall plan to the parents during the initial consultation.
PATIENT HISTORY AND PHYSICAL FINDINGS
A general history and physical examination should be performed.
The clinician should concentrate on family history or concurrent known congenital abnormalities, which could indicate a genetic syndrome that could require further workup and genetic consultation.
FIG 1 • Paley classification of congenital femoral deficiency. (Copyright 2006, Sinai Hospital of Baltimore.)
The facies and upper extremities are examined, looking for abnormal appearance or multiple congenital anomalies, which can indicate a genetic syndrome. In such cases, genetic consultation should be obtained.
Hip ROM
Abduction–adduction and flexion ROM are examined in the supine position. Thomas test (hip extension) is performed to measure fixed flexion deformity of the hip. Hip internal rotation–external rotation is measured in the prone position, together with the thigh–foot angle. Muscle length tests include popliteal angle (hamstring length) and prone knee bend (rectus femoris muscle).
ROM is measured and contractures are identified and quantified in degrees. A popliteal angle of more than 0 degrees and prone knee bend less than supine knee bend indicate tightness of the hamstring and rectus femoris muscles, respectively.
Contractures need to be treated in preparation for lengthening. Lengthening of the rectus femoris and hamstring muscles is recommended for positive muscle tightness.
Knee ROM
Flexion and extension knee ROM is measured in the supine and prone positions.
Greater than 10 degrees of fixed flexion deformity should be corrected during preparatory procedures. A fixed flexion deformity can be present.
Knee stability (anteroposterior)
The Lachman test and the anterior and posterior drawer tests are performed. The clinician looks for posterior sag and rotatory instability. The amount of instability is measured:
Grade I: mild with endpoint
Grade II: moderate with endpoint
Grade III: moderate or severe with no endpoint
Anteroposterior knee instability is common.
Knee stability (rotatory)
The rotatory stability of the knee joint is examined by internally and externally rotating the tibia on the distal femur in flexion and extension. The presence of subluxation with rotation of the tibia on the distal femur is noted.
External rotatory instability is a common finding that is secondary to a contracted iliotibial band, which can lead to rotatory subluxation of the knee and patellar dislocation.
Patellar stabilit.
The clinician should flex the knee and palpate the alignment of the patella to the notch in flexion. Tracking of the patella is assessed from 0 to 90 degrees. The clinicians should attempt to push a thumb into the intercondylar notch.
If the examiner's thumb is able to palpate the intercondylar notch with the patient's knee flexed, this denotes lateral subluxation or dislocation of the patella.
Patellar instability is common and can be an indication of lateral rotatory instability of the knee and contracture of the iliotibial band.
The clinician should look at the overall appearance of the foot and ankle.
Any missing rays or positional abnormalities are noted. Ankle ROM is tested with knee flexed and extended. Inversion and eversion ROM is tested.
The amount of dorsiflexion, plantarflexion, inversion, and eversion is recorded. Equinovalgus deformity with missing lateral rays indicates concurrent fibular hemimelia. Subtle increase in eversion ROM indicates fibular hypoplasia or a ball-and-socket ankle joint.
IMAGING AND OTHER DIAGNOSTIC STUDIES
During the initial evaluation of an infant with CFD, supine long anteroposterior (AP) and lateral view radiographs should be obtained that include the pelvis and both lower extremities. Both lower limbs are pulled down to make sure both knees are in maximum extension (FIG 2A).
The supine long AP view radiograph should be assessed for the overall appearance of the ossific anatomy. This radiograph should allow the physician to classify the type of CFD.
The lengths of both femora and both tibiae should be measured. The difference between them is the LLD, not including the foot. The clinicians should measure from the lateral acetabular edge to the midpoint of the knee joint space for the femoral lengths and from the same midpoint of the knee joint space to the end of the tibial ossific nucleus for the tibial lengths. The amount of current LLD can be used with the multiplier method to predict the overall LLD at maturity.1,2,10
The acetabulum should be assessed for dysplasia using the center–edge (CE) angle (even in infants) and the acetabular index (AI).
The long lateral view radiograph of the lower extremity is assessed for underlying fixed flexion deformity of the knee.
The anterior cortical line of the distal femur should normally be colinear with the anterior cortical line of the proximal tibia. A flexion angle between these lines represents fixed flexion deformity of the knee.
Other imaging studies that are useful include magnetic resonance imaging (MRI) and arthrography of the hips. If the presence of a true pseudarthrosis of the proximal femur is questionable, an evaluation with MRI can be used in an attempt to visualize the presence or absence of a cartilaginous connection between the femoral head and shaft (FIG 2B,C).
Arthrography under general anesthesia is the gold standard to determine the presence of pseudarthrosis versus delayed ossification of the proximal femur. While the arthrogram is obtained, the lower extremity is manipulated and the proximal femur is visualized.
If the proximal femur and femoral head move as a unit, this denotes a cartilaginous connection in the proximal femur, and the CFD is classified as type 1b. The arthrogram is also useful to differentiate between Paley types 2a and 2b. Both 2a and 2b might have a femoral head present; the difference is whether the femoral head is fused to the acetabulum or not. If dye can be injected into a joint space, the hip can be classified as type 2a.
DIFFERENTIAL DIAGNOSIS
If the patient has bilateral CFD, the clinician must consider the following differential diagnoses:
Camptomelic syndrome
Femoral hypoplasia (unusual facies syndrome)
FIG 2 • A. Supine AP view radiograph of an infant with Paley type 1b congenital femoral deficiency (subtrochanteric type). An assistant pulls the limbs down to negate the anterior hip flexion. The limb lengths can be directly measured from the radiograph to determine the limb length discrepancy. B,C. Lateral view radiograph and corresponding MRI, respectively, show a true pseudarthrosis of the proximal femur. The hip is classified as Paley type 2. The mobility of the femoral head can be determined under fluoroscopy. (Copyright 2007, Sinai Hospital of Baltimore.)
NONOPERATIVE MANAGEMENT
Shoe lifts, orthoses, and prostheses are used for the nonoperative management of LLD. All children should receive a shoe or prosthesis with a lift when they begin to cruise the furniture. A simple shoe lift of an amount equal to 1 cm less than the LLD is used in most cases in which LLD is less than 10 cm (FIG 3A).
It is helpful to supplement the lift with an articulated ankle–foot orthosis (AFO) for ankle support from the long lever arm of the shoe lift. If the lift is more than 10 cm, a prosthetic foot connected to an AFO is preferred both to reduce weight and improve cosmesis.
FIG 3 • Examples of conservative treatment before lengthening. A. Simple shoe lift. If the shoe lift is greater than 5 cm, a concurrent ankle–foot orthosis should be used. B. Prosthetic lift is used for more severe cases of limb-length discrepancy. (Copyright 2007, Sinai Hospital of Baltimore.)
The clinician should avoid splinting the foot in equinus because it might cause an equinus contracture.
In children younger than 6 years, a limb-length radiograph should be obtained every 6 months to assess LLD and prescribe a new lift.
After age 6 years, annual assessment and prescription is adequate.
In more severe cases with hip and knee fixed flexion deformity, it might be necessary to extend the orthotic or prosthetic support above the knee (FIG 3B).
SURGICAL MANAGEMENT
Patients with types 1a, 1b, 2a, and 2b CFD can be managed successfully with lengthening reconstruction surgery as opposed to prosthetic reconstruction surgery.
Before undergoing lengthening reconstruction surgery, patients with certain knee and hip deformities and deficiencies should undergo preparatory procedures to prevent complications during lengthening and to reconstruct the knee and hip joints. This chapter will present the preparatory surgical procedures of the hip and knee and the external fixation method we prefer for CFD lengthening surgery.
Type 1 CFD
Type 1 CFD is the most reconstructable.
Before lengthening, hip stability should be determined radiographically. The best indicator is the CE angle. If the CE angle is less than 20 degrees, a Dega osteotomy should be performed before lengthening. In addition, the AI should be less than 30 degrees. If the CE angle is borderline 20 degrees but the AI is high, it is better to err on the side of caution and perform a Dega osteotomy (FIG 4).
Coxa vara should be corrected before lengthening if the neck–shaft angle is less than 120 degrees. When coxa vara and hip dysplasia are present and when the coxa vara is severe, the superhip procedure is performed. The pelvic and femoral osteotomies should be performed 6 to 12 months before the first lengthening. The superhip procedure is a comprehensive surgery to correct the proximal femoral and hip deformities with concurrent soft tissue releases.
FIG 4 • A. Three-year-old girl with type 1a congenital femoral deficiency and concurrent right hip dysplasia shown by the diagonal acetabular sourcil and a center–edge angle of 8 degrees (left center–edge angle = 25 degrees). B.Postoperative radiograph after Dega osteotomy shows corrected dysplastic acetabulum. (Copyright 2006, Sinai Hospital of Baltimore.)
At the conclusion of a successful superhip procedure, the reorientation of the proximal femur allows for ossification of the proximal femur (type 1b [ie, femoral neck or subtrochanteric region]). This ossification converts type 1b to type 1a and usually occurs within 2 years of the superhip procedure. Lengthening is not performed in type 1b cases until they convert to type 1a (except in special circumstances).
Type 2 and 3 CFD
The strategies that should be used to treat types 2 and 3 CFD are complex and beyond the scope of this chapter. A summary of the strategies is provided below.
Type 2 CFD
The presence or absence of a mobile femoral head in the acetabulum determines the treatment strategy. Although MRI and arthrography can be used to examine the femoral head for mobility, opening the hip joint capsule is the only definitive way to determine the presence or absence of a mobile femoral head.
If the femoral head does not move in the acetabulum, it should not be joined to the femoral shaft. If the femoral head is mobile, it can be connected to the remainder of the femur by a complicated procedure in which the femoral neck is reconstructed.
We call this procedure superhip 2, and it converts type 2a CFD to type 1a. For type 2b CFD, only the superhip soft tissue release is performed without the osteotomy. The flexion contracture of the hip is released and the fascia lata excised. Serial lengthenings with external fixation to the pelvis, femur, and tibia are performed before skeletal maturity. A pelvic support osteotomy is performed during the final lengthening at skeletal maturity.
Type 3 CFD
Type 3a can be treated like type 2b. Patients can undergo hip release, serial lengthenings, and pelvic support osteotomy or they can be treated by prosthetic fitting options, including prosthetic reconstruction surgery (ie, Syme amputation or rotationplasty3).
Prosthetic reconstruction surgery is recommended for type 3b CFD, which includes a stiff knee joint (less than 45 degrees of motion). Although type 3a can be converted to type 2b, the treatment would consist of four or more lengthenings. Rotationplasty is recommended for type 3a because it provides a more predictable functional result than does lengthening (FIG 5).
Lengthening
The number of lengthenings that are required for type 1 CFD is determined by the initial LLD prediction. Patients with type 1a CFD typically undergo their first lengthening at age 3 years. Patients with type 1b typically undergo lengthening closer to age 4 years. Between 5 and 8 cm can be obtained during each lengthening.
For type 1 CFD, the femur should be lengthened by using a distal femoral osteotomy instead of a proximal femoral osteotomy.
Distal osteotomies allow for better regenerate bone formation because they have a broader cross-sectional diameter and because the bone is not sclerotic or dysvascular, which often is seen in the proximal femur of patients with CFD. Distal osteotomies can also be used to simultaneously correct the valgus deformity of the distal femur.
Proximal osteotomies are used to correct the external femoral torsion and proximal varus deformities. Proximal osteotomies are not used for lengthening because of poor regenerate bone formation. A proximal osteotomy can be used for deformity correction with a concurrent distal osteotomy for lengthening.
Soft tissue releases are performed during lengthening to prevent subluxation and stiffness of the knee and hip. Soft tissue releases that were addressed during a previous superhip or superknee procedure do not need to be repeated.
Lengthening Via External Fixators
Femoral lengthening with an external fixator can be performed with various devices.
The essential principle of lengthening with external fixation is to stabilize the knee during lengthening while allowing for knee motion. This is accomplished by using hinges and external fixation of the tibia.
From 1987 to 2000, only the Ilizarov apparatus was used with fixation across the knee joint with a hinge. This method has previously been described.8 We did not use a monolateral external fixator because it could not articulate across the knee joint.
FIG 5 • A,B. Patient who underwent rotationplasty for treatment of Paley type 3 congenital femoral deficiency. The rotationplasty allows the patient to motor his prosthetic leg as a below-the-knee amputee with excellent function. C.Preoperative photograph of a patient with Paley type 3 congenital femoral deficiency. D. Photograph obtained immediately after the patient (C) underwent rotationplasty. (Copyright 2007, Sinai Hospital of Baltimore.)
Since 2000 a method was developed that combined the pediatric Limb Reconstruction System (LRS) (Orthofix, Inc., McKinney, TX) with Sheffield Ring Fixation System components (Orthofix) to articulate across the knee with fixation to the tibia. Both Ilizarov and Orthofix parts are used to create this construct.
Preoperative Planning
Preoperative evaluation consists of obtaining radiographs and performing a physical examination as previously described.
The radiographs are assessed as previously described and the CFD is reclassified if progressive ossification has occurred.
During each visit before the first surgical reconstruction, LLD is recalculated to increase accuracy so that the overall strategy can be altered as needed.10
Positioning
The patient undergoing the superhip procedure is positioned supine on the operating table with a bump placed under the ipsilateral sacrum to tilt the pelvis about 35 to 40 degrees. The entire lower extremity to include the groin, iliac crest, and gluteal region is prepared to the subcostal margin (FIG 6A).
The patient undergoing the initial femoral lengthening is positioned supine on the operating table with a radiopaque grid placed under the operating table pad. A small bump is placed under the ipsilateral sacrum to allow the extremity to rest in a patella-forward position. The entire lower extremity to include the groin, iliac crest, and gluteal region is prepared (FIG 6B).
Approach
The approach for the superhip and superknee procedure is the same extended lateral approach to the hip, femur, and knee as described in the following section.
The lengthening procedures are performed using percutaneous techniques.
FIG 6 • A. Patients undergoing a superhip procedure should be prepared and draped to allow access to the iliac crest, gluteal region, adductor region, and the entire lower extremity. The patient is tilted 35 to 40 degrees on a sacral bump. B. Preoperative positioning for initial limb lengthening. The positioning allows access to the pelvis, proximal femur, and the remainder of the lower extremity. (Copyright 2007, Sinai Hospital of Baltimore.)
TECHNIQUES
SUPERHIP PROCEDURE
An anterior incision is made starting two to three fingerbreadths posterior to the anterior superior iliac spine and at the level of the iliac crest. This incision gently curves to the posterolateral border of the femur along the level of the posterolateral intermuscular septum.
A second S-shaped incision is made from the lateral side of the patellar tendon and is extended proximally in line with the intermuscular septum at the level of the knee joint. A bridge of intact skin is left between the two incisions. A recently developed distal alternative is an anterior midline incision.
If the extremity is significantly short, these incisions become one extended approach.
The flap of skin and the subcutaneous tissues are reflected in a full-thickness fashion off the deep fascial layer anteriorly.
For the proximal incision, the interval between the TFL muscle and the sartorius muscle is dissected.
For the distal incision, the fascia lata's anterior and posterior borders are exposed at the level of the superior pole of the patella. The posterior border blends with the posterolateral intermuscular septum (TECH FIG 1A,B).
At the TFL–sartorius interval, the fascia is split longitudinally. Care is taken to avoid injury to the lateral femoral cutaneous nerve. This is accomplished by releasing the fascia on the tensor fascia lata side of the intermuscular septum.
This fascial incision is extended distally to join the anterior margin of the fascia lata that was previously exposed.
The fascia lata is cut distally at the tibia and is reflected proximally if a concurrent superknee procedure with knee ligamentous reconstruction is not required. If ligamentous reconstruction is planned, the fascia lata is cut proximally and reflected distally.
The TFL muscle is reflected proximally and posteriorly on its posterior pedicle. Its anterior vascular pedicle (ie, lateral femoral circumflex vessels) can be cauterized and cut.
The TFL muscle is separated from the underlying gluteus medius muscle distally. If the muscles do not separate well, the interval is left alone. The surgeon must remember that any tissue that is inserting onto the greater trochanter is the gluteus medius muscle and must remain intact (TECH FIG 1C).
The conjoint tendon of the rectus femoris, before it divides into the direct and reflected heads, is transected.
The psoas tendon is exposed and released at the level of the pelvic brim. The surgeon must realize that the femoral nerve is much closer to both the rectus femoris muscle and psoas tendon in patients with CFD. Therefore, the femoral nerve is identified and protected before the aforementioned releases (TECH FIG 1D).
If the anterior fascia of the thigh and the fascia of the sartorius muscle are tight, they are released. The lateral femoral cutaneous nerve is identified and protected before releasing the fasciae.
The femur should now be adducted, internally rotated, and flexed such that the greater trochanter is brought to the level of the center of the femoral head and the posterior border of the greater trochanter is parallel to the floor. If the proximal femur cannot be placed in this position, there is an abduction contracture of the hip joint. In these cases, the glutei muscles should be elevated off the greater trochanter along with the vastus lateralis muscle as a trigastric flap.
The posterior border of the vastus lateralis at the intermuscular septum is identified and dissected free of the femur subperiosteally. The dissection is continued proximally along the posterior aspect of the greater trochanter. It is important to peel a thin layer of cartilage with the flap because the tendinous covering over the trochanter is thin.
The dissection of the posterior border of the greater trochanter is continued proximally to sharply reflect the tendinous portions of the gluteus medius and minimis muscles as a continual sling (TECH FIG 1E).
The flap of the conjoint gluteus–quadriceps tendon is sharply dissected and reflected from posterior to anterior off the trochanter. It is then reflected anteriorly off the intertrochanteric line, leaving the anterior hip capsule intact. The dissection should remain extra-capsular. The capsule should not be incised, and the pelvic trochanteric ligament running superior to the hip joint capsule should never be cut. During the release, the piriformis tendon should be identified and released, which allows the femur to rotate internally. The surgeon should avoid releasing the hip capsule from the greater trochanter because doing so can lead to hip instability, lateral subluxation, and dislocation (TECH FIG 1F).
An alternative approach for patients with mild abductor contractures is to split the iliac crest apophysis and dissect the gluteal muscles in a subperiosteal fashion. This allows the gluteal muscles to slide distally, resolving the abductor contracture. This exposure is later used for the Dega osteotomy. At the completion of the procedure, the iliac crest is then resected by 1 cm to allow for closure of the apophysis with no tension.
An arthrogram of the hip is obtained. The femoral head and neck are placed in a neutral orientation to the pelvis by extending and maximally adducting the hip joint.
Plate Fixation of Proximal Femur
The preferred method of fixation is the hip plate method. The preferred implant is the 130-degree pediatric cannulated blade plate (custom ordered from Smith & Nephew, Memphis, TN). If this is unavailable, the pediatric sliding hip screw (Smith & Nephew, Memphis, TN) can be used with a second screw for rotational control.
The first step is to place a guidewire from the tip of the greater trochanter to the center of the femoral head. This creates the proximal femoral joint orientation line (TECH FIG 2A).
A second guidewire is inserted in the center of the femoral neck to the center of the femoral head, at a 45-degree angle with the initial guidewire. The second guidewire is then visualized under a lateral fluoroscopic view to confirm its position in the center of the femoral head ossific nucleus (TECH FIG 2B,C). The correct orientation on the lateral fluoroscopic view is when one can see a “bullseye” created by the concentric circles of the arthrographic outline of the femoral head and femoral neck with the ossific nucleus in the center.
TECH FIG 1 • Superhip procedure. A. Incision. B. Reflection of anterior flap. A point 4 to 6 cm posterior to the anterior superior iliac spine is marked on the skin, and the lateral “bump” is marked on the skin. These two points are connected with a curvilinear line that extends distally on the posterior margin of the vastus lateralis muscle belly. The second incision is a distal S incision that begins at the level of the lateral intramuscular septum on the side of the thigh and proximally at the level of the superior pole of the patella and extends to the lateral margin of the patellar tendon to the tibial tubercle. The anterior flap is dissected off the deep fascia to the midline of the thigh. C. Reflection of fascia lata and TFL muscle. The anterior and posterior margins of the fascia lata are dissected as described, with the fascia lata being released proximally at the musculotendinous junction of the TFL muscle. The fascia lata is reflected distally to its insertion on the tubercle of Gerdy of the proximal tibia. The TFL muscle is dissected off the gluteus minimis and medius and reflected proximally. D. Hip flexion contracture release. After the TFL muscle is reflected proximally, the dissection is continued medially under the sartorius muscle. The rectus femoris tendon is the first structure identified as it inserts on the anterior inferior iliac spine. This tendon is released, and the psoas muscle and tendon are then identified. Before release of the psoas tendon, the femoral nerve, which is adjacent to the psoas tendon, is identified and decompressed. E,F.Release of abduction and external rotation contracture. The confluent tendinous portions of the hip abductor muscles (gluteus minimis and medius muscles) and the vastus lateralis muscle are sharply dissected off the cartilaginous greater trochanter, creating a continuous musculotendinous sling. This release resolves the abduction contracture and allows access to the piriformis tendon. FL, fascia lata; m, muscle; n, nerve; RF, rectus femoris; TFL, tensor fascia lata; VL, vastus lateralis. (Copyright 2007, Sinai Hospital of Baltimore.)
The appropriate sized cannulated blade plate chisel is driven over the femoral neck guidewire to create a path for the blade plate (TECH FIG 2D). The chisel should be oriented perpendicular to the straight posterior border of the greater trochanter. The chisel is removed, and the appropriately-sized cannulated blade plate is inserted over the femoral neck guidewire (TECH FIG 2E).
At the intertrochanteric level, two wires are inserted perpendicular and parallel to the side plate. A sagittal saw is used to remove a triangular segment of bone. The first cut is parallel to the plate, and the second cut is perpendicular to the plate. The width of the second cut is equal to the diameter of the femoral diaphysis (TECH FIG 2F).
A second subtrochanteric osteotomy is performed by cutting obliquely from the lateral starting point of the previous parallel cut. This cut divides the femur into two segments and leaves a medial buttress of bone (TECH FIG 2F).
The distal femoral segment is extended, abducted, and internally rotated and aligned with the plate allowing the femoral segments to overlap. The bone ends have to overlap because of the constraints of the surrounding soft tissues. The amount of overlap determines the amount of shortening of the distal segment that is required (TECH FIG 2G,H).
A third osteotomy is performed perpendicular to the distal femoral shaft at the level of overlap (usually 1 to 2 cm distal to the second osteotomy site). The distal femoral segment is reduced to the plate and fixation is completed with three or four screws. The resected bone segment is used in the Dega osteotomy at the end of the procedure (TECH FIG 2I).
For type 1b cases (delayed femoral neck ossification), an adjunct treatment can be performed by drilling a channel with a diameter of 3.2 to 3.8 mm into the femoral neck and packing bone morphogenetic protein (INFUSE Bone Graft, Medtronic, Inc., Memphis, TN) into the cartilaginous tunnel to induce ossification of the femoral neck (TECH FIG 2I).
Pelvic Osteotomy
The next step is to perform the Dega osteotomy. To expose the ilium, the iliac crest apophysis is split and detached with the periosteum. The outer table of the ilium is subperiosteally dissected, and the hip abductor muscles are lifted from anterior to posterior. The posterior dissection is continued to the sciatic notch and should not cross the triradiate cartilage (TECH FIG 3A).
The pelvic osteotomy is curved along the lateral cortex from the anterior inferior iliac spine (AIIS) to the triradiate cartilage posteriorly. At the AIIS, the osteotomy goes through both tables of the ilium. It is important to cut the apophysis and periosteum transversely at this level to allow the osteotomy to separate anteriorly. The osteotomy does not enter the sciatic notch but passes anterior and parallel to the level of the triradiate cartilage. The apex of the osteotomy should start 2 cm above the hip joint and is inclined to the triradiate cartilage medially (TECH FIG 3B).
TECH FIG 2 • (A) After arthrography of the hip, a Kirschner wire is placed from the tip of the greater trochanter to the center of the femoral head (B,C). Second Kirschner wire is inserted into the femoral neck toward the center of the femoral head, creating a 45-degree angle with the initial guidewire (arrow). This will produce a 130-degree neck–shaft angle after the completion of the osteotomy. The position of the second guidewire is confirmed to be in the center of the femoral head by obtaining a lateral fluoroscopic view. (D) Cannulated chisel is driven over the femoral neck guidewire to create a path for the 130-degree blade plate. (E) Cannulated 130-degree pediatric blade plate is inserted over the femoral neck guide pin to its final position. The protruding plate is used as a guide for the initial bone cuts. The plate should be parallel to the posterior trochanteric border to ensure correction of the flexion deformity. (F) Sagittal saw is used to remove a triangular segment of bone (first osteotomy). The two bone cuts are parallel and perpendicular to the plate. The width of the perpendicular cut is equal to the femoral diaphysis. The second osteotomy is started at the parallel cut and directed distally in an oblique fashion. This creates a medial buttress on the proximal femoral fragment. (G,H) Distal femoral segment is adducted, extended, internally rotated, and aligned with the side plate. The distal segment overlaps the proximal segment due to the soft tissue constraints. This determines the amount of shortening required and the position of the third osteotomy. The third osteotomy is performed perpendicular to the distal femoral diaphysis. (I) Distal femoral segment is reduced to the side plate and secured with three to four cortical screws. For type 1b cases, an adjunct treatment can be performed by drilling a channel with a diameter of 3.2 to 3.8 mm into the femoral neck and packing bone morphogenetic protein (INFUSE Bone Graft, Medtronic, Inc., Memphis, TN) into the cartilaginous tunnel. (Copyright 2009, Sinai Hospital of Baltimore.)
The osteotomy is levered distally and laterally to cover the femoral head. The large opening wedge is maintained by inserting the resected femoral segment. The end point of correction is a horizontal sourcil (TECH FIG 3C).
The stability of the graft is tested by attempting to pull the graft from the osteotomy site with a Kocher clamp. The graft should be fully within the lateral cortical margins of the ilium. Typically, the graft is extremely stable and no further fixation is needed.
With the abductor sparing approach, the medial apophysis is pried off the crest. The crest is then resected using a saw until the medial and lateral apophysis can be repaired without excessive tension.
With the trigastric flap approach there is no apophysis to repair, but the trigastric tendon has to be fixed to the cartilaginous trochanter. The hip should be slightly abducted to make sure the abductors are under tension.
The tensor fascia lata is then sutured to the greater trochanter.
The femur is placed in neutral abduction, and the conjoint abductor–quadriceps tendon is sutured directly into the cartilaginous greater trochanter with absorbable suture under some tension.
The TFL is also sutured to the greater trochanter.
The incision is closed in layers. A suction drain is used and is left in place until the draining stops (less than 10 cc per 24 hours), which can take several days. Prophylactic antibiotics are administered intravenously until the drain is removed.
A spica cast is applied with the hip in full extension, neutral abduction, and neutral rotation. The knee is splinted in full extension. The cast is removed 6 weeks after surgery. Recently, we have been splitting the cast in surgery and allowing early ROM and bathing between splinting with the cast.
TECH FIG 3 • (A) Dega osteotomy is performed by exposing the outer table of the ilium by splitting the iliac crest apophysis and lifting the abductor muscles. (B) Osteotomy curves from the anterior inferior iliac spine to the triradiate cartilage along the lateral cortex of the ilium. The osteotomy does not enter the sciatic notch or cross the triradiate cartilage. In the coronal plane, the apex of the osteotomy starts 2 cm above the joint and is inclined toward the triradiate cartilage medially. (C) Osteotomy is levered distally to cover the femoral head, and the opening wedge is filled with the resected femoral segment graft. The end point of correction is a horizontal sourcil that is confirmed with the use of fluoroscopy. (D) The iliac crest is now resected to provide both additional bone graft for the Dega osteotomy and to relax the hip abductors to correct the preoperative abduction contracture. (E) Preoperative radiographic example of bilateral congenital femoral deficiency. (F) Postoperative radiograph obtained after superhip procedure. A Dega osteotomy is completed with horizontal sourcil. Note the complete femoral head coverage. (Copyright 2009, Sinai Hospital of Baltimore.)
SUPERKNEE PROCEDURE
Incision and Dissection
If significant knee instability is present, a superknee procedure should be performed conjointly with the superhip procedure. The superknee procedure can address ACL and PCL insufficiency, patellar subluxation or dislocation, and maltracking. Different parts of the procedure can be used depending on the knee pathology.
A long, S-shaped incision is made to expose the knee. The anterior and posterior margins of the fascia lata are incised longitudinally. The fascia lata is transected as proximally as possible and reflected distally until its insertion onto the tibia (TECH FIG 4A,B). The proximal aspect of the incision is developed as described for the superhip procedure.
The biceps femoris tendon should be Z-lengthened if knee flexion deformity is present or if the tibia is externally rotated on the femur. The peroneal nerve should first be identified as it emerges from behind the biceps femoris muscle and decompressed at the first and second tunnel of compression in the anterior and lateral compartments of the lower leg (TECH FIG 4C).9
TECH FIG 4 • A. S-shaped incision is made on the lateral aspect of the distal thigh. B. The anterior and posterior margins of the fascia lata are identified and dissected proximally. The fascia lata is transected just distal to the tensor fascia lata muscle belly. The fascia lata is then dissected distally to the tubercle of Gerdy on the tibia. C. The tensor fascia lata is split longitudinally into two equal strips of tendon. (Copyright 2009, Sinai Hospital of Baltimore.)
Patellar Stabilization
The fascia lata is split into two longitudinal strips to make two ligaments. A Krackow whipstitch5 is used to run a nonabsorbable suture from the free end of the fascia lata toward the tubercle of Gerdy in a tubular fashion (TECH FIG 5A).
A lateral release of the capsule leaving the synovium intact is performed in all cases.
A Grammont procedure4 is performed to medially transfer the patellar tendon if patellar maltracking is significant.
This procedure is done by releasing the patellar tendon from proximal to distal and from lateral to medial, leaving intact a long sleeve of periosteum distally. The periosteal extension of the tendon is elevated with the tendon so that the detached tendon remains tethered distally. The patella and patellar tendon are shifted medially and sutured into position with an absorbable suture (TECH FIG 5B).
A modified Langenskiöld procedure is performed when fixed patellar subluxation or dislocation is present (see description below in Alternative Step for Patellar Realignment).
TECH FIG 5 • A. Tendons are then prepared with a Krackow whipstitch to form a tubular graft. B. Grammont patellar tendon medialization is performed by incising the medial and lateral borders of the patellar tendon past the tibial tubercle. The patellar tendon is elevated off the tibial tubercle apophysis with an extension of periosteum that remains intact distally. The patellar tendon can then be shifted medially. (Copyright 2009, Sinai Hospital of Baltimore.)
The lateral capsule is cut to, but not through, the synovium. The vastus lateralis muscle is elevated off the intermuscular septum.
If the patella is still tethered laterally by the vastus lateralis muscle, its tendon is released from the lateral aspect of the patella and transferred centrally to the quadriceps tendon under minimal tension.
The lateral release is extended distally to the lateral aspect of the patellar tendon. If a Grammont procedure4 is to be performed, the incision is extended past the tibial tuberosity along the crest of the tibia so that the proximal periosteum is elevated as described above.
ACL Reconstruction
Next, a MacIntosh intra-articular or extra-articular ACL reconstruction (or both) is performed. The lateral collateral ligament (LCL) is identified. Two tunnels are made. One tunnel is placed under the LCL and does not enter the knee joint (TECH FIG 6A). The other tunnel is made subperiosteally, from anterior and proximal to posterior and distal, over the lateral intramuscular septum of the femur.
A hole is made in the posterior knee joint capsule by inserting a curved clamp from the “over-the-top” position.
The posterior limb of the fascia lata is passed under the LCL. An ACL reamer is used over a guidewire to create a bony tunnel in the proximal tibial epiphysis. The wire is inserted from the anteromedial aspect of the tibia and is directed to the center of the tibial epiphysis. The outer diameter of the actual graft is measured, and the hole in the epiphysis is reamed to this diameter (TECH FIG 6B).
A suture passer is passed through the tibial epiphyseal tunnel and out the posterior capsule of the knee to exit laterally anterior to the septum. The fascia lata suture is pulled through the knee and the bony tunnel using the suture passer. A bioabsorbable headless screw (Arthrex, Inc., Naples, FL) is used to secure the graft to the tunnel (TECH FIG 6C). The ACL graft is tensioned and sutured with the knee reduced and in full extension to prevent creation of a fixed flexion deformity of the knee.
If only an extra-articular ACL repair is needed, the fascia lata is looped back after passing under the LCL and the lateral intramuscular septum. The fascia lata is sutured to itself and no tunnel is made (TECH FIG 6D,E). To prevent loosening, the graft can be reinforced and retensioned after fixation by passing a nonabsorbable suture through bone at the point at which the graft loops over the intermuscular septum.
Extra-articular or intra-articular PCL reconstruction is performed.
TECH FIG 6 • A. Lateral collateral ligament and the distal aspect of the posterior intramuscular septum are identified. The posterior limb of the fascia lata graft is passed under the lateral collateral ligament. B. Posterior limb is then passed through a subperiosteal tunnel under the lateral intermuscular septum. The graft enters the subperiosteal tunnel from the anterior aspect and heads distally toward the posterior knee joint capsule. Inset, Bony tunnel is created in the proximal tibial epiphysis. A wire is placed into the epiphysis medial to the patellar tendon. The wire is directed toward the lateral femoral condyle and exits the tibial epiphysis at the midpoint of the ossification center. This wire is overdrilled with the appropriate-size cannulated drill, depending on the graft size. C. Suture passer is inserted into the bony tunnel and retrieved at the posterior aspect of the knee with a curved clamp. After the graft has been passed under the lateral collateral ligament and over the intramuscular septum, it is pulled through the subperiosteal tunnel, through the posterior joint capsule, and out the tibial epiphyseal tunnel. The graft is secured with a headless bioabsorbable interference screw. D,E. Alternatively, instead of a combined intra-articular and extraarticular repair, an isolated extraarticular reconstruction can be performed. The graft is then tensioned with the limb in full extension, folded back onto itself, and secured with nonabsorbable suture. TFL, tensor fascia lata. (Copyright 2009, Sinai Hospital of Baltimore.)
Extra-articular PCL Reconstruction (Reverse MacIntosh Procedure Developed by Paley) 8
The anterior skin flap is elevated off the knee and dissected and reflected medially until the entire vastus medialis muscle can be visualized.
The anterior limb of the fascia lata is not tubularized. It is passed first under the patellar tendon and then through a medial capsular tunnel. The graft is then passed through a subperiosteal tunnel around the adductor magnus tendon. Finally, it is sutured to itself with nonabsorbable suture (TECH FIG 7).
This extra-articular ligament is tensioned with the knee in 90 degrees of flexion to prevent an extension contracture.
To expose the medial side, the medial soft tissue flap is reflected to the midline.
Intra-articular PCL Reconstruction
The peroneal nerve is identified, decompressed, and protected.
The lateral head of the gastrocnemius muscle is then released from the femur. The posterior aspect of the proximal tibial epiphysis is identified to the midline.
An anterior-to-posterior drill hole is made through the epiphysis, and the anterior limb of the fascia lata is passed from anterior to posterior, exiting near the midline posteriorly.
Another drill hole that passes through the medial distal femoral epiphysis from anteromedial to posterolateral is made. The ligamentized fascia lata is pulled through the posterior capsule and into the medial femoral epiphyseal tunnel using its leading suture. It is fixed in place with a biotenodesis absorbable screw (Arthrex) after tensioning in flexion.
Alternative Step for Patellar Realignment: Langenskiöld Reconstruction
If the patella has a fixed lateral subluxation or dislocation, a modified Langenskiöld patellar reconstruction is performed before the knee ligamentous reconstruction (intra-articular and extra-articular).
TECH FIG 7 • A,B. Reverse MacIntosh (extra-articular posterior collateral ligament) procedure is performed by passing the anterior limb of the fascia lata graft under the patellar tendon and through a window created in the medial joint capsule. The graft is then passed through a subperiosteal tunnel under the adductor magnus tendon, looped back onto itself, and secured with nonabsorbable suture. (Copyright 2009, Sinai Hospital of Baltimore.)
This procedure is performed through the same superknee incision and can be performed as a part of the overall reconstruction.
The retinaculum is released on both the medial and lateral aspect of the patella. This is the same incision used for the lateral release (TECH FIG 8A,B).
The incision is taken down to the synovial layer without violating the synovium. The synovium is then carefully dissected free of the undersurface of the quadriceps muscle proximally and from the patellar tendon distally.
Medially, the capsule is incised proximally in a longitudinal fashion, separating the vastus medialis muscle from the vastus intermedius muscle.
The distal medial capsule is cut transversely at the level of the joint line. The capsule is separated from the synovium as far as the medial gutter.
Once the synovial layer has been separated completely from the overlying tissues, its connection to the patella is incised circumferentially (TECH FIG 8C,D). The quadriceps and patellar tendon are left attached to the patella and the entire extensor mechanism can be shifted medially.
TECH FIG 8 • A,B. Initial step in the modified Langenskiöld reconstruction is to perform a medial and lateral capsulotomy. The knee joint capsule is dissected away from the synovium medially and laterally. The synovium also is dissected free from the quadriceps tendon and the patellar tendon. C,D. Synovium is released from the patella circumferentially, leaving the quadriceps and patellar insertions intact. E,F.The hole in the synovium is closed longitudinally with absorbable suture, leaving the patella with the quadriceps and patellar attachments extra-articular. The Grammont elevation and Grammont medial patellar tendon shift are then performed (see TECH FIG 5). G. Knee is positioned in full extension, and the new position for the patella is marked on the synovium. H. A longitudinal incision is created in the synovium. I,J. The synovium is sutured to the patella in a circumferential fashion. K. The medial capsule is advanced and sutured onto the lateral side of the patella. The lateral capsule is not repaired. L,M. If an extra-articular posterior collateral ligament (reverse MacIntosh) procedure is performed, the Langenskiöld reconstruction is completed before the ligamentous reconstruction. Fascia lata graft passes through the advanced medial capsule and is sutured onto itself. BF, biceps femoris muscle; m., muscle; RF, rectus femoris tendon; VM, vastus medialis. (Copyright 2009, Sinai Hospital of Baltimore.)
The synovium is now a free tissue layer with a patellasized hole in the center.
The synovial hole is sutured longitudinally with absorbable suture (TECH FIG 8E,F). The patella is left extra-articular at this point.
The Grammont procedure is performed as described above, and the patellar tendon is shifted medially. The patellar tendon is secured with absorbable suture.
The patella with the quadriceps muscle is now realigned medially to its new position and a marking pen is used to mark its new location on the synovium (TECH FIG 8G).
The synovium is incised longitudinally with the knee in full extension (TECH FIG 8H). The patella is inserted into this new position and sutured circumferentially to the synovium with a continuous absorbable suture (TECH FIG 8I,J).
The medial retinacular flap is now advanced over the patella and sutured to the lateral side of the patella (TECH FIG 8K).
Once the modified Langenskiöld reconstruction is completed, the ACL and PCL knee ligamentous reconstruction, as previously described, is performed (TECH FIG 8L,M).
FEMORAL LENGTHENING OF TYPE 1 CFD: ORTHOFIX FIXATOR TECHNIQUE
Preparatory Surgery
The preparatory surgery that is required consists of a Dega pelvic osteotomy for underlying hip dysplasia (CE angle less than 20 degrees or AI greater than 30 degrees), rectus femoris tendon release, and iliotibial band release at the level of the superior pole of the patella. If the popliteal angle is greater than 10 degrees, the biceps femoris tendon and medial hamstrings should be released.
If the patient has undergone a superhip procedure, the preparatory surgery has been completed and repeat releases of the soft tissues are not necessary.
If the preparatory surgery has not been performed and the Dega osteotomy is needed, it should be combined with excision of the fascia lata, superknee reconstruction, or both. Alternatively, the soft tissue releases can also be performed simultaneously with the lengthening procedure.
Placement of Femoral Fixator
An arthrogram of the involved knee is obtained under fluoroscopy. In the lateral view, the femoral condyles are rotated until they superimpose each other. This is considered a “true lateral of the knee” (note that this is not the patella-forward position—actually the patella will be externally rotated approximately 10 degrees in this position).
The center of knee rotation is identified. The center of rotation is the intersection of the posterior cortical line and the distal femoral physeal line.
A 1.8-mm Ilizarov wire is inserted into the distal femoral physis at the center of rotation and parallel to the distal femoral joint line in the frontal plane (TECH FIG 9A,B).
The pediatric LRS is aligned with the hinge-axis wire through the most distal clamp hole. A commercially available “sandwich” clamp is used in the distal clamp, which provides a second layer of pin holes more anteriorly (TECH FIG 9C,D).
If these are not available, two pin clamp lids can be joined by 30-mm bolts to create a sandwich clamp.
The external fixator rail is aligned with the femur in the sagittal view and the most proximal half-pin is inserted at the level of the base of the greater trochanter (this pin should be distal to the apophysis).
The half-pins are inserted using the cannulated drill technique: a 1.8-mm or 1.5-mm wire is first inserted into the bone and the position is checked with fluoroscopy in both the AP and lateral views.
TECH FIG 9 • A,B. Intraoperative fluoroscopic images show arthrography of the knee. The lateral view is obtained, and the posterior aspects of the femoral condyles are superimposed to create the perfect lateral view. The hinge reference wire is inserted at the intersection of the posterior femoral cortical line and the distal femoral physis. This marks the center of rotation of the knee joint. C,D. Bone model shows LRS sandwich clamp placed distally, with the most distal hole containing the hinge-axis wire. The first distal half-pin is placed on the anterior row one hole proximal to the hinge-axis pin. E. Example of pediatric Orthofix rail with a three-hole cube placed on the distal half-pins to allow a third half-pin to be inserted into the distal fragment. F. Radiograph shows acute valgus correction performed at the osteotomy site for lengthening. (Copyright 2006, Sinai Hospital of Baltimore.)
If the wire is in the center of the bone, a cannulated drill is used to overdrill the wire. The half-pin is then inserted in a perfect position.
Half-pins placed in the anterior half of the femoral diaphysis can result in a fracture either during the lengthening process or after frame removal.
The most distal half-pin is placed one hole proximal and anterior to the knee axis reference wire.
At this point, the position of the hinge axis is a fixed point to the initial distal half-pin. The reference axis wire is removed.
An LRS without a sandwich clamp is now placed on the two half-pins. The additional half-pins are placed proximal and distal. Three half-pins should be placed in each segment.
If concurrent distal valgus deformity is being corrected, a swivel clamp should be used at the proximal clamp site when placing the first two half-pins.
When using the pediatric LRS, the standard clamp offers only three half-pin sites and one site is occupied by the knee axis dummy pin. Therefore, a three-hole Ilizarov cube should be connected to the two half-pins that occupy the pediatric Orthofix clamp and a third half-pin placed through the cube more proximal (TECH FIG 9E).
After all half-pins are placed, the template LRS with swivel clamp is removed and a distal femoral osteotomy is performed using the multiple drill hole technique.
The distal femoral valgus deformity is acutely corrected, and the LRS with sandwich clamp attachments is placed on the half-pins, stabilizing the correction (TECH FIG 9F).
Placement of Tibial Fixator
The distal pins should be in the upper deck of the double-decker sandwich clamp.
The only pin in the lower deck of the sandwich clamp is a dummy pin (ie, partial pin that is captured by the clamp and protrudes away from the patient but does not enter the patient's limb) in the distal lower hole.
This dummy pin is the hinge-axis pin.
A Sheffield clamp (Orthofix) is applied to the hinge-axis pin. Conical washers are placed medial and lateral to the Sheffield clamp to reduce friction. A single-hole Ilizarov cube and set screw are placed laterally.
The hinge-axis pin and Sheffield clamp have now created a mechanical hinge (TECH FIG 10A,B).
The Sheffield clamp is temporarily tightened and positioned parallel to the LRS rail. A one-third Sheffield arch is then attached to the clamp and arched medially to be anterior to the tibia. The arch should be perpendicular to the tibia in the sagittal plane (TECH FIG 10C–E).
A single-hole Ilizarov cube is placed on the Sheffield arch, and an AP half-pin is placed in the proximal tibia. As the first pin is being secured to the Sheffield arch, the knee must be in full extension and reduced.
Testing and Completion of the External Fixator Construct
After the first half-pin is inserted into the tibia, the Sheffield clamp is loosened and the hinge tested with gentle ROM of the knee.
TECH FIG 10 • A,B. Bone model with a dummy pin inserted into the distal posterior hole of the LRS sandwich clamp that replaces the hinge-axis wire. A Sheffield clamp is attached to the hinge dummy pin to create the knee hinge. C. Bone model with Sheffield arch attached to Sheffield hinge clamp. The initial tibial half-pin is placed in an anterior-to-posterior direction, denoted by the empty Ilizarov cube. Additional pins can be attached via Ilizarov cubes. At least three half-pins should be inserted to obtain adequate stability. D,E. Clinical photographs of two examples of the Sheffield arch attachment to the tibia. At least three half-pins are used for fixation. (Copyright 2006, Sinai Hospital of Baltimore.)
TECH FIG 11 • A,B. Lateral views of the Orthofix pediatric LRS device with hinge construct bridging the knee. The knee hinge allows for full flexion (A) and extension (B) while protecting the knee from subluxation during lengthening. C. Clinical photograph shows a completed Orthofix external fixator for femoral lengthening in a patient with congenital femoral deficiency. The knee extension bar is constructed by building Ilizarov cubes from the half-pins to the Sheffield arch. Sockets are used to connect the extension bar to the frame, which allows for easy removal of the bar during physical therapy. (Copyright 2006, Sinai Hospital of Baltimore.)
If the motion is smooth, a drop-leg test is performed.
The drop-leg test consists of lifting the lower extremity off the bed and fully extending the knee. The thigh is supported and the lower leg dropped.
If the knee flexes with no catching or friction, two additional half-pins are placed in the tibia.
If there is friction during the drop-leg test, the hinge and knee rotation axis needs to be examined and adjusted. Usually, the dummy axis pin can be slightly bent and the hinge axis reoriented to the knee rotational axis. After the axis pin adjustment, the dropleg test is repeated until knee ROM is smooth, with no friction (TECH FIG 11A,B).
A knee extension bar is built using Ilizarov parts and is extended from the previously placed three-hole cube to the Sheffield arch. Another strategy is to attach a separate Ilizarov cube to the protruding ends of the distal femoral half-pins and extend it to the Sheffield arch.
This knee extension bar is used intermittently during the day and full-time at night (TECH FIG 11C).
The bar is used to prevent a knee flexion contracture.
At the conclusion of the procedure, Botox, 10 units per kilogram of body weight, is injected into the proximal quadriceps using multiple injection sites.
This is to reduce quadriceps muscle spasms and pain during knee flexion stretches.
POSTOPERATIVE CARE
Patients who have undergone the superhip or superknee procedures are placed into a 1-1/2 hip spica cast.
The involved limb is placed in neutral abduction, neutral rotation, and 0 degrees of extension. The knee is held in full extension, and the foot is included.
The cast is removed at 6 weeks, and gentle ROM of all joints is performed as well as weight bearing as tolerated.
Patients undergoing femoral lengthening require close follow-up and intensive rehabilitation. Patients are usually discharged on postoperative day 3 or 4.
The lengthening begins on day 5 or 7 at a rate of 0.75 to 1.0 mm per day.
The patient is assessed every 2 weeks in the outpatient clinic with radiographic and clinical examinations.
Pin-site problems, nerve function, hip and knee ROM, and knee subluxation are assessed.
The joint location, limb alignment, regenerate bone quality, and length gained are assessed radiographically.
The rate of distraction is adjusted according to regenerate bone quality and joint ROM.
Physical therapy is begun on postoperative day 1. During the distraction phase, physical therapy is continued daily, with formal therapy occurring 5 days per week.
The formal therapy consists of one or two sessions with a therapist each day, with 1 hour of land therapy and 1 hour of hydrotherapy.
The patient also undergoes two physical therapy sessions at home each day with the parents.
During therapy, the patient should perform exercises that obtain knee flexion and maintain knee extension.
Knee flexion should be maintained at greater than 45 degrees but not more than 90 degrees.
If knee flexion is 40 degrees or less, lengthening should be discontinued or slowed and knee rehabilitation should be increased.
If there is no improvement, lengthening is discontinued.
During the distraction phase, passive exercises are most important; during the consolidation phase, passive plus active exercises are important. Hip abduction and extension are two important hip exercises.
During the consolidation phase, the formal therapy can be reduced to three sessions per week if the patient is doing well. Weight bearing is allowed as tolerated.
The frame can be removed from the femur and tibia after the regenerate bone has healed.
A prophylactic Rush pin (Zimmer, Inc., Warsaw, IN) is placed in the femur at the time of external fixation removal (FIG 7). Application of the Rush pin prevents refracture after lengthening.
The frame is removed under general anesthesia, and radiographs in the AP and lateral views are obtained.
At this point, the pin sites are cleaned, prepared, and then isolated with Tegaderm dressings (3M Healthcare Ltd, St. Paul, MN). The entire lower extremity to include the hip, iliac crest, and gluteal region is prepared and draped.
A 1.8-mm Ilizarov wire is inserted into the tip of the greater trochanter and driven into the center of the proximal femur. An intraoperative lateral view radiograph after external fixation removal is used to place the starting point on the greater trochanter. The 1.8-mm wire is drilled or tapped into the femur and then overdrilled with a cannulated 3.2-mm or 4.8-mm drill to create the starting hole for the prophylactic Rush pin insertion, depending on whether a 3.1-mm (1/8 inch) or 4.6-mm (3/16 inch) Rush pin is used.
If needed, the femur is then sequentially reamed using Thandled hand reamers (ie, Foresight nail reamers [Smith & Nephew]) until the desired pin diameter is obtained. The hand reamer should be slightly bent at the tip to allow for careful guidance down the canal under fluoroscopic control.
After the reaming is complete, the Rush pin is inserted and should reach just above the distal femoral physis. Its tip might need to be slightly bent to navigate the curves of the femur.
The small proximal incision is closed, and the pin sites are dressed. The pin sites are not manipulated or released to decrease the risk of concurrent infection.
Antibiotics are administered intravenously during the procedure, and oral antibiotics are used for 7 days postoperatively.
FIG 7 • A. AP view radiograph of right femur of a patient with Paley type 1a congenital femoral deficiency after initial lengthening of 8 cm. B. Postoperative AP view radiograph of femur after external fixation removal with insertion of Rush pin to protect the newly consolidated regenerate bone. C. Longstanding lateral view radiograph shows the inserted Rush pin after external fixation removal. (Copyright 2007, Sinai Hospital of Baltimore.)
If a significantly problematic pin site or pin-site infection is present at the time of removal, the prophylactic intramedullary rod placement is delayed for 2 weeks and the affected limb is placed into a hip spica cast.
Physical therapy is discontinued for 1 month to avoid fracture through the regenerate bone or a pin hole.
Physical therapy is restarted 1 month after frame removal and Rush pin application. With the Rush pin in place, no cast or brace is needed. The patient is allowed partial weight bearing.
OUTCOMES
Saghieh and associates12 studied our first 79 consecutive patients with Paley type 1 CFD. The patients underwent 99 femoral lengthenings between January 1988 and December 2000. Medical charts and radiographs were retrospectively reviewed. Fifty-nine patients (73 lengthenings) had Paley type 1a and 20 patients (26 lengthenings) had Paley type 1b CFD. Forty-six (58%) were female and 33 (42%) were male patients. The mean patient age was 12.3 years (age range, 1.5 to 62.3 years). The lengthenings were divided into three age groups: toddler (younger than 6 years), juvenile (between 6 years and skeletal maturity), and adult (skeletally mature). Because 19 patients each underwent more than one lengthening (18 underwent two lengthenings, and 1 underwent three lengthenings), each lengthening was evaluated independently as a separate lengthening and studied for its own results and complications.
Distraction gap, percent of femur lengthened, external fixation time index, degree of preservation of knee motion, result score, and complications were compared among the groups. The complications and ROM data were routinely recorded, and the data were obtained from a review of the charts. Radiographic measurements were obtained from preoperative lower limb alignment AP view radiographs (teleoroentgenograms), compensating for magnification, and from lateral view radiographs of the femur and tibia. The CE angle and neck–shaft angle also were measured, preferably by using an AP view radiograph of the pelvis. The average follow-up from the time of removal of the external fixator was 69 months (range, 19 to 132 months).
The average discrepancy in femoral length was 9.1 cm (range, 1.2 to 22.1 cm) preoperatively and 4.1 cm (range, 14.7 to 2.3 cm) postoperatively. The mean distraction gap was 5.8 cm (range, 2.4 to 12.0 cm). The average duration of treatment with external fixation was 5.9 months (range, 2 to 15.9 months) with an external fixation time index of 1.07 months/cm (range, 0.49 to 2.38 months/cm). The result score was excellent in 61 (61.6%) lengthenings, good in 29 (29.3%), fair in 7 (7.1%), and poor in 2 (2%).
Excellent and good results were achieved in 91% of patients. No significant differences in most of the studied parameters, including result score, were observed among the different groups. The two younger groups experienced a higher incidence of fracture (no prophylactic rodding was used in this group). The adult group experienced a higher incidence of delayed union and joint stiffness. However, the overall complication rates were similar among the three groups. We prefer to begin lengthening at an early age so that additional needed lengthenings can be spaced in time.
Currently, we are reviewing our experience since 2000. Our outcome study includes more than 250 patients with CFD who have undergone more than 350 lengthening procedures.
COMPLICATIONS
Flexion contracture of the kne.
A significant knee flexion contracture places the knee at risk for posterior subluxation.
One of the primary goals of physical therapy is to maintain knee extension and to continue to obtain knee flexion. Both the surgeon and therapist need to closely monitor the patient's ROM and must be in regular communication if difficulties arise.
To prevent fixed flexion deformity, a knee extension bar is used every night and part-time during the day. If the patient experiences a loss of motion, therapy must be increased and the patient assessed immediately.
Acute pin-site infections can lead to increased pain and decreased motion and should be immediately treated with oral or intravenous antibiotics.
If significant soft tissue tightness is present in the quadriceps muscle, the distraction rate should be decreased. However, decreasing the distraction rate should be followed closely with radiographs to prevent premature consolidation. If Botox was not used at the index procedure, the surgeon should consider injecting the quadriceps muscle with 10 units of Botox solution per kilogram of body weight. We perform the Botox injection under anesthesia or sedation for the younger patient.
Adduction and flexion contractures of the hip.
Hip adduction contractures place the hip joint at risk for subluxation and dislocation during the lengthening process. Hip adduction should be assessed at the time of the lengthening surgery. If a contracture is present, an adductor tenotomy should be performed.
Hip ROM and stretching is addressed by the therapist on a daily basis. If a contracture is a concern initially, an abduction pillow is used at night. If the patient has subluxated or dislocated the hip in a previous procedure, the external fixator should be extended above the hip with a hinge device similar to that used for the knee. Hip flexion contracture might occur when the patient is positioned in a wheelchair for prolonged periods of time.
The patient should not only stretch during the therapy sessions, but also should be placed in a prone position on a daily basis. Occasionally, a repeat rectus femoris tendon release along with a release of the anterior thigh fascia is performed at the time of external fixation removal. Iliopsoas contracture does not occur during the lengthening because the distraction site is distal to the psoas insertion.
Nerve injury
Nerve injury is unusual with femoral lengthening. Complaints of pain in the foot are usually referred pain from nerve entrapment. Quantitative sensory testing is the best method to identify early nerve entrapment.7
The nerve problem can be treated by slowing the distraction or nerve decompression. The peroneal nerve should be decompressed at the neck of the fibula if symptoms continue or pressure-specified sensory device testing is positive.9
Premature consolidatio.
Premature consolidation usually occurs during the first 2 cm of distraction and is rare after 4 cm of distraction. In a young child, the latency period should not be more than 7 days.
Increasing pain with distraction or difficulty while turning the distracting unit are signs of possible preconsolidation. Radiographs should be obtained to assess the regenerate bone. If the fibrous interzone disappears, the turning rate should be increased (ie, five quarter-turns per day) and additional radiographs obtained within 1 week.
If one of the cortices has bridged with narrow bone, continued distraction at an increased rate can be performed.
The physician must warn the parents that the patient may experience or hear an audible “pop” during distraction. This will be followed by a mild to moderate increase in pain. However, the distraction will become easier and surgery can be avoided.
If the regenerate site is consolidated with abundant bone, the pins might bend or become deformed. This type of preconsolidation is addressed with a repeat osteotomy 1 to 2 cm proximal to the original site. The surgeon should not attempt to repeat an osteotomy at the same regenerate site because the patient will have increased bleeding and poor regenerate bone formation. If the fibrous interzone is greater than 5 mm, lengthening should be slowed (ie, two or three turns per day).
Regenerate bone failur.
Partial defects in the bone are not uncommon on the lateral cortex. Sequential radiographs obtained during the distraction phase must be closely followed for increasing fibrous interzone distance and poor regenerate bone formation.
Regenerate bone failure is prevented by slowing the distraction rate when signs of poor regenerate formation are present. During the consolidation phase, a partial defect can be treated with dynamization to increase healing of the regenerate bone.
If the defect persists and encompasses less than 25% of the bone diameter, a rigid intramedullary rod placed at the time of removal will allow for ossification during a prolonged time period (6 to 12 months).
If the regenerate bone failure is more severe, open autogenous bone grafting should be performed after first excising the interposing fibrous tissue.
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