Craig J. Della Valle
DEFINITION
At less than 90 degrees of active knee flexion, a total knee arthroplasty (TKA) has inadequate range of motion (ROM) for performing many activities of daily living. The required ranges of motion for daily activities are as follows4,12:
67 degrees of flexion for normal gait on level ground
83 degrees of flexion to climb stairs
90 to 100 degrees of flexion to descend stairs
93 degrees of flexion to stand from a standard-height chair
105 degrees of flexion to tie a shoe
Flexion contractures can be equally disabling: a flexion contracture of more than 15 degrees usually is considered pathologic, because it greatly inhibits normal gait.
ANATOMY
The primary impediments to exposure of the revision TKA, particularly a stiff TKA, are the extensor mechanism and the patella. The exposure can be thought of as a progressive release or “unleashing” of the extensor mechanism.
The four tethers of the extensor mechanism (FIG 1) are:
Proximal: quadriceps tendon and musculature
Medial: medial joint capsule and retinaculum with the insertion of the vastus medialis
Lateral: lateral joint capsule and retinaculum with the insertion of the vastus lateralis
Distal: patellar tendon
The blood supply to the patella is provided by an anastomotic ring of vessels supplied by the geniculate arteries. It is important to try to avoid complete devascularization of the patella, because avascular necrosis can occur.
The blood supply to the skin overlying the knee travels from the deeper tissues up through the superficial fascia and does not run superficially. If skin flaps are required at the time of surgery, they must be full-thickness, therefore, to avoid skin necrosis.
PATHOGENESIS
Many potential causes for stiffness following TKA exist, and multiple mechanisms may act in concert in a given patient, resulting in suboptimal ROM.
Poor perioperative pain control or suboptimal physical therapy. In rare cases, a chronic regional pain syndrome develops, characterized by severe pain, cutaneous hypersensitivity, vasomotor disturbance, and stiffness.
Technical issues related to the original surgical procedure may play a role.
FIG 1 • Anterior view of the knee showing the patella, patellar tendon, quadriceps tendon, vastus medialis oblique muscle, and vastus lateralis.
Femoral component
Oversized: leads to tightness in flexion
Internally rotated: leads to patellar maltracking or an asymmetric flexion gap
Inadequate distal femoral resection: leads to tightness in extension and a potential flexion contracture
Over-resection of the distal femur: requires a thicker polyethylene insert to obtain stability, thereby leading to tightness in flexion
Inadequate removal of posterior femoral osteophytes: leads to tenting of the posterior capsule and flexion contracture or osteophytes that can impinge on the tibial polyethylene insert, limiting flexion
Anterior placement of the femoral component: leads to “over-stuffing” of the patellofemoral joint
Tibial component
Most commonly, inadequate or reverse slope of the tibial cut, which leads to tightness in flexion; internal rotation, which leads to patellar maltracking; oversized component, which leads to soft tissue impingement and pain
Elevation of the joint line (particularly if >1 cm): leads to poor ROM secondary to altered patellofemoral joint mechanics
Inadequate resection of the tibia: leads to tightness in both flexion and extension
Patellar component
Under-resection of the patella: leads to overstuffing of the patellofemoral articulation. The native patella–prosthetic composite should be equivalent in thickness to the patella before resection.
Excessive patellar resection: leads to weakness of the extensor mechanism with initial extensor lag and eventual flexion contracture
Inadequate medialization of the component: leads to patellar maltracking
Inadequate removal of lateral patellar osteophytes: leads to impingement and pain
Ligamentous imbalance: flexion-extension mismatch (typically too tight in flexion, particularly with a cruciate-sparing design) or varus–valgus instability
Poor component fixation: failed ingrowth of cementless components or inadequate cement mantle around cemented components, resulting in persistent pain that inhibits physiotherapy
Patient-related factors
Poor preoperative ROM (the best predictor of postoperative ROM is preoperative ROM)
Genetic predisposition to scarring and stiffness
A history of previous surgery on the knee that has led to stiffness or a patella baja (shortening of the patellar tendon)
Noncompliance with physical therapy
Obesity (soft tissue envelope of the posterior thigh and leg limits flexion)
Stiffness or arthritis of the ipsilateral hip
Deep infection
Heterotopic ossification
NATURAL HISTORY
The natural history of the stiff TKA is poor. Even with time, patients' ROM rarely improves enough to positively impact their gait pattern, and chronic pain develops.
Flexion contractures are equally poorly tolerated, as is inadequate flexion. Flexion contractures greater than 15 degrees limit the ability to stand up straight and cause substantial fatigue when walking.
Patients with only mild stiffness (ie, ROM near 90 degrees) may improve slightly (5 to 10 degrees) in the first 2 years after surgery, reaching a level of flexion that is tolerable for most activities of daily living.
PATIENT HISTORY AND PHYSICAL FINDINGS
The history is a critical part of the evaluation to determine which of the factors listed under Pathogenesis have led to stiffness; in most cases, more than one factor is at work.
Direct questions should be asked to determine whether pain control was adequate in the postoperative period.
Did the patient have severe pain postoperatively that limited his or her ability to perform physical therapy?
For how long postoperatively did the patient require narcotics? Is the patient still taking narcotics and still in severe pain?
Does the patient have hypersensitivity of the skin overlying the incision or other complaints that suggest neurogenic pain or a chronic regional pain syndrome?
How was the patient's stiffness addressed postoperatively?
Did he or she undergo a manipulation under anesthesia (MUA) postoperatively?
Has he or she undergone any other operative procedures (eg, open or arthroscopic release) in an attempt to improve ROM?
Does any element of the history suggest infection?
Wound drainage that persisted for more than a few days after surgery
The use of antibiotics for more than 24 hours postoperatively
Persistent pain that is of a different character than the pain the patient had before the surgery
Inspect the skin for the presence of a past or present sinus, indicating infection. Densely adherent skin is much harder to close and may represent a higher risk for necrosis.
Evaluate the patient's ROM. Flexion of less than 90 degrees and a flexion contracture of more than 15 degrees are considered pathologic. Loss of ROM affects gait and ability to perform activities of daily living.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Standing anteroposterior (AP), lateral, and patellar radiographs should be obtained to identify component loosening, malposition, or improper sizing (FIG 2A).
Patella baja and joint line position also should be noted (FIG 2B). Severe ligamentous imbalance may be readily apparent on the plain radiographs. Patellar maltracking also can be identified (FIG 2C), as can an unresurfaced patella, which may be causing pain that leads to stiffness.
Serial radiographs often are helpful in confirming component loosening.
A CT scan to determine femoral and tibial component rotation often is performed (FIG 2D–F). If component malposition is identified (eg, internal rotation), the components are revised.3
FIG 2 • A. Lateral view of a stiff TKA showing an oversized femoral component. B. Stiff TKA with joint line elevation and patella baja. C. Lateral dislocation of the patella. D. CT scan of the distal femur of a right knee. The top line marks the epicondylar axis, and the bottom line marks the posterior condylar line; the component in this case is internally rotated. Note the dislocated patella. CT scans of the proximal tibia identifying the apex of the tibial tubercle (E) and alignment of the tibial component (F). These images are overlaid on each other to determine the rotation; normal is 18 degrees of internal rotation; the component in this case is internally rotated 16 degrees.
Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level are obtained before every revision TKA.
If either is elevated, an aspiration of the knee joint is obtained and sent for a cell count with differential and cultures, including aerobic, anaerobic, and acid-fast bacilli, and fungi. A white blood cell count above 3000 is considered consistent with infection.
Patients must have been off antibiotics for at least 2 weeks before the knee aspiration.
At the time of revision, additional cultures are taken from within the joint, and an intraoperative frozen section is taken from the synovial tissues. An average of more than 10 polymorphonuclear cells identified within tissue (and not fibrin) is consistent with infection.
Nuclear medicine studies, such as a triple-phase bone scan, occasionally are helpful in identifying subtle loosening but are not routinely obtained.
DIFFERENTIAL DIAGNOSIS
Deep infection
Component malposition (eg, internal rotation of the femur or tibia)
Patellar maltracking or overstuffing of the patellofemoral joint
Improper component sizing
Ligamentous imbalance (eg, tightness in flexion)
Component loosening
Chronic regional pain syndrome
NONOPERATIVE MANAGEMENT
If the patient is seen early in the postoperative period (less than 6–12 weeks postoperatively), he or she can be managed with a combination of the approaches discussed in this section.
Aggressive pain management is supervised by a physician with expertise in this area—usually an anesthesiologist who specializes in pain management.
If chronic regional pain syndrome is being considered, a sympathetic blockade often is administered.
Intensive physical therapy, stressing active and passive ROM exercises, may be begun.
In cases of flexion contracture, dynamic splinting or the use of serial casts can be tried in an attempt to obtain full extension.
MUA also can be performed. When I perform MUA, I prefer to place an indwelling epidural catheter at the same time that will remain in place for several weeks after the procedure to assist with administration of medication for pain control. Patients are sent home with a pump to administer the medication and are carefully monitored by a pain control specialist.
MUA seems to be most effective and is associated with a lower rate of complications (eg, periprosthetic fracture) if performed within 3 months of the index procedure.
The literature is unclear as to the magnitude of benefit derived. Most studies show that patients improve after MUA, but that their final ROM is less than that of their nonmanipulated counterparts.
Other potential complications of MUA include rupture of the patellar or quadriceps tendon, periprosthetic fracture of the femur or tibia, and wound dehiscence. The manipulation should be performed using a short-lever arm with the patient completely relaxed until a firm endpoint is reached.
SURGICAL MANAGEMENT
The decision to proceed with revision TKA for stiffness should be considered carefully and only after a full investigation as to the cause or causes of stiffness. The patient must be fully informed of the risks of the procedure and educated that the ROM may not improve, even with further surgery. It is crucial to work with a pain management specialist and a physical therapist to ensure that stiffness does not recur postoperatively.
Options for surgical management include:
Arthroscopic débridement with manipulation2,5,7,15
This can be performed in highly selected patients with well-fixed, appropriately aligned components. The procedure is technically demanding, and the results reported in the literature are variable, with most studies showing mild improvements in ROM (15 to 30 degrees, on average).
The technique includes release of the posterior cruciate ligament (if present), clearing of scar from the suprapatellar region, and, typically, MUA once the scar has been cleared.
Flexion contractures are harder to address arthroscopically, but a posterior release can be performed using small, open, medial and lateral incisions.
Open arthrolysis with exchange of the modular polyethylene liner1,9,10,13
This procedure also can be performed in selected patients with well-fixed, appropriately aligned components. It often is difficult to fully release the posterior capsule to treat flexion contractures, however, and it is unclear whether this technique has any benefit over arthroscopic release.
Revision TKA6,8,10,11,14
Revision TKA is the most appropriate treatment for most patients. It allows for optimization of component alignment, size, and rotation, while providing the opportunity to restore the joint line.
It affords complete access to the posterior capsule to perform a capsulectomy and remove any retained osteophytes from the previous surgical procedure.
An additional benefit is the option of using a more constrained polyethylene insert, if desired, to optimize stability if extensive releases are performed.
If a large flexion contracture is being addressed, a flexion-extension mismatch often is present (ie, extension space smaller than the flexion space), and constrained and even hinged implants may be required.
Preoperative Planning
The history, physical examination, plain radiographs, and CT scan (if obtained) are reviewed before a definite decision is made whether the components are to be removed or retained.
The ESR, CRP, complete blood cell count, and culture results are reviewed to determine whether a deep infection is present.
If any of the prosthetic components are to be retained, the operative note from the previous procedure must be reviewed to definitely identify manufacturer, model, and size so that appropriate, matching replacement implants and trials are available on the day of surgery.
An examination under anesthesia confirms the limits of motion.
FIG 3 • The lower extremity is draped free with a bump underneath the hip. A leg positioner holds the extremity in the desired position.
Positioning
The operative extremity is draped free from the hip to the ankle, and a tourniquet is placed on the upper thigh.
A bump placed underneath the ipsilateral hip assists in keeping the leg upright.
A leg holder keeps the leg in the desired position for surgery.
An elastic bandage placed on the lower leg defines the malleoli, which are used as a reference for tibial cut alignment (FIG 3).
Approach
The workhorse approach for exposure in revision TKA is the medial parapatellar approach with complete excision of intra-articular scar tissue. This approach is useful for most revision TKAs.
In the stiff knee, however, a more extensile approach may be required.
If additional exposure is needed, a quadriceps snip can be performed.
This maneuver assists in freeing the proximal tether of the extensor mechanism, thereby improving exposure.
Benefits include relative simplicity of performance and repair, no need to alter postoperative rehabilitation protocols, and clinical results that have been shown to be equivalent to those in patients who have undergone a revision TKA without a snip.
If a more extensile exposure is needed, the extensor mechanism can be completely released proximally with a V-Y quadricepsplasty (see Chap. AR-27) or distally with a tibial tubercle osteotomy (see Chap. AR-26).
TECHNIQUES
MEDIAL PARAPATELLAR ARTHROTOMY WITH COMPLETE INTRA-ARTICULAR RELEASE
Skin incision
Previous skin incisions are used whenever possible.
Avoid parallel incisions. If choosing among multiple previous incisions, the most lateral one is selected, because the blood supply is derived predominantly from the medial side.
Full-thickness flaps are raised, if required.
The arthrotomy extends from the apex of the quadriceps tendon, around the medial aspect of the patella and just medial to the tibial tubercle (TECH FIG 1A).
On entering the joint, large amounts of scar typically are encountered (TECH FIG 1B); these prevent proper exposure and contribute to stiffness.
TECH FIG 1 • A. Arthrotomy for the medial parapatellar approach. P marks the patella. B. Large amounts of scar in the suprapatellar pouch. C. A medial release has been performed. D. The line identifies the boundary between the scar and the extensor mechanism. Everything below the extensor mechanism is resected. E. Scar tissue is dissected out from underneath the extensor mechanism using a knife, scissors, or electrocautery. F. Scar has been completely cleared from the suprapatellar pouch, and the medial and lateral gutters have been re-established.
A medial release is performed with electrocautery by subperiosteally releasing a continuous soft tissue sleeve all the way to the posteromedial corner of the tibia and the semimembranous insertion (TECH FIG 1C).
This allows for external rotation of the tibia, which relaxes the extensor mechanism and improves exposure.
The junction between scar and the extensor mechanism is identified (TECH FIG 1D). The scar is meticulously removed from underneath the extensor mechanism laterally (TECH FIG 1E) and from underneath the joint capsule medially until the medial and lateral gutters have been re-established (TECH FIG 1F).
A thin layer of soft tissue is left on the distal femur to prevent excessive bleeding and also to prevent the extensor mechanism from becoming readherent in this area.
The scar tissue is carefully cleared from behind the patellar tendon by identifying the interval between the patellar tendon and the scar behind it to release the patellar tendon from the proximal tibia.
At this point, the modular polyethylene liner is removed to allow for patellar eversion or subluxation. In most cases, patellar subluxation is preferred, because it places less tension on the extensor mechanism and provides adequate exposure in most cases.
If difficulty is encountered, soft tissue can be peeled off the lateral border of the patella to make it more mobile, and any osteophytes that are present can be removed.
If exposure still cannot be accomplished, a formal lateral retinacular release may be required.
This release involves a full-thickness division of the capsule along the lateral border of the patella from the proximal tibia (just lateral to the patella tendon) to the vastus lateralis.
A lateral release performed from the inside out eliminates the need to raise additional skin flaps.
QUADRICEPS SNIP
If inadequate exposure has been afforded by the medial parapatellar arthrotomy and a complete intra-articular release, a quadriceps snip often provides enough additional exposure to complete the procedure safely.
The snip is made at the apex of the arthrotomy, obliquely across the quadriceps tendon at a 45-degree angle in line with the fibers of the vastus lateralis (TECH FIG 2).
At the end of the procedure, the snip is closed side-toside using nonabsorbable suture.
The postoperative therapy protocol is not altered if a quadriceps snip has been performed.
TECH FIG 2 • Quadriceps snip.
COMPONENT REMOVAL
The femoral and tibial components are then carefully removed as described in Chapter AR-26.
The patella then is assessed. Its thickness is determined (TECH FIG 3), and if the composite is considered to be too thick (ie, >25 mm for women and >30 mm for men) or in an otherwise suboptimal position (eg, lateralized), the component is removed.
If the component is to be retained, any osteophytes or unresurfaced sections of the native patella are removed.
TECH FIG 3 • Patellar thickness is assessed. In this case, the patella was 27 mm thick in a female patient, and the component was revised.
RECUTTING THE UPPER END OF THE TIBIA AND PERFORMING A POSTERIOR RELEASE
The proximal tibia is recut perpendicular to its mechanical axis with neutral slope. Either an intraor extramedullary guide may be used. A neutral slope is recommended, so rotation of the cut is not important at this point. The revision component often has an appropriate amount of slope built in (5–7 degrees) so that rotation in the optimal position can be set later.
A laminar spreader then is inserted both medially and laterally, and the scar tissue in the posterior aspect of the knee along with any remnant of the posterior cruciate ligament, if present, is removed completely to re-establish the flexion space and restore full extension (TECH FIG 4A).
At this point, ligamentous balance is assessed and appropriate releases are performed until the flexion gap is of equivalent size medially and laterally.
A curved osteotome then is used to release any remaining capsule from the posterior aspect of the femur and to clear any residual osteophytes retained at the time of the original TKA (TECH FIG 4B).
Given the tendency to elevate the joint line in revision TKA, a complete posterior capsular release is performed in all cases.
TECH FIG 4 • A. Performance of a posterior release and capsulectomy. The posterior capsule has already been removed on the lateral side. B. A curved osteotome is passed subperiosteally behind the femur to complete the posterior release, re-establishing the flexion space and restoring full extension. The patella has been subluxed laterally but not everted.
CREATING THE TIBIAL PLATFORM
The tibia is prepared first, because tibial height affects both the flexion and extension gaps.
The tibial component is then sized to maximize coverage of the upper end of the tibia.
A stem typically is used to provide support for the revision component. Stems also assist with component alignment. It is necessary to remember that the tibial shaft is offset posteromedially in relation to the center of the upper end of the tibia, and a stem that allows for offset often is required to optimize coverage of the upper end of the tibia (the stem is used to bring the component anterior and lateral in most cases).
The tibial trial component is then placed in the appropriate amount of external rotation; typically, the center of the component is aligned with the junction of the medial and middle thirds of the tibial tubercle (TECH FIG 5).
See Chapters AR-23 and AR-25 for additional details.
TECH FIG 5 • The center of the tibial component is placed in line with the medial third of the tibial tubercle to be in appropriate external rotation.
CHOOSING THE FEMORAL TRIAL SIZE AND AUGMENTS
Sizing of the femoral component can be difficult but is a critical portion of the procedure. If the original component is thought to have been too large, a smaller trial component is selected.
The surgeon must keep in mind that, although it is desirable to leave the patient's knee “somewhat loose in flexion” in cases of stiffness, this does risk flexion instability. Consideration should be given to using a more constrained insert in cases of revision TKA for stiffness.
The knee initially is trialed with a long intramedullary stem to assist with determining appropriate valgus alignment; a shorter stem can be substituted later if desired. Stems are used routinely, both to support the revision component and to assist with alignment.
The initial augments typically used include a small posterolateral augment, to encourage appropriate external rotation of the revision component, and small distal augments placed both medially and laterally, to distalize the femoral component in response to the tendency of revision TKA to elevate the joint line.
Appropriate external rotation of the femoral component is checked using the epicondylar axis of the femur (TECH FIG 6A). The surgeon also can check to make sure that a “piano” or “boot” sign is present when the cut surface of the femur is viewed from above (TECH FIG 6B). This sign indicates that the cut on the lateral side is deeper than that on the medial side, confirming appropriate external rotation of the femoral cut.
TECH FIG 6 • A. The epicondylar axis is used to ensure appropriate external rotation of the femur. B. View of the distal femur from above showing the “piano” or “boot” sign, confirming appropriate external rotation of the femoral component.
TRIALING AND CLOSURE
The knee is now trialed with varying thicknesses of polyethylene liners to ensure:
Full extension of the knee (TECH FIG 7A)
Adequate flexion of the knee (TECH FIG 7B). A good predictor of postoperative flexion is that achieved at the time of surgery with the knee flexed against gravity.
Adequate varus–valgus stability
Good patellar tracking. If patellar tracking is not acceptable, the rotation of the femoral and tibial components must be carefully assessed and changed if necessary until the patella tracks well.
Restoration of the joint line to within 1 cm of its normal position. The easiest way to asses the joint line is to compare the superior pole of the patella to the superior flange of the revision femoral component.
Various combinations of augments and polyethylene liners should be tried until the optimal combination is found; this may take a considerable amount of time to achieve.
The revision components are now assembled on the field. The stems can be either firmly press-fit into the canal, with cement placed only around the metaphyseal segment of the component (see TECH FIG 4C), or fully cemented, depending on the surgeon's preference. Antibiotic-loaded cement is recommended, given the higher risk of infection in the setting of revision TKA.
The knee is closed in at least 90 degrees of flexion, because this has been shown to increase final flexion. Following closure of the arthrotomy, ROM and patellar tracking are carefully assessed once again.
TECH FIG 7 • A. Full extension of the knee. B. More than 120 degrees of knee flexion. The patella is tracking centrally. C. The components are cemented in the metaphyseal region of the revision component (just distal to the modular junction between the revision component and the stem), and the stem is press-fit tightly into the canal.
POSTOPERATIVE CARE
Perioperative care must be monitored closely in conjunction with a pain management specialist and a physical therapist.
Patients are placed on a continuous passive motion (CPM) machine starting at 0 to 90 degrees in the recovery room, with the setting advanced as tolerated. CPM is used for 4 to 6 hours per day, and patients must understand that it is an adjunct to, not a substitute for, active and passive ROM exercises.
The indwelling epidural catheter is continued for up to 6 weeks. The patient is seen by the surgeon and the pain management specialist weekly for the first 6 weeks to monitor progress.
Patients are engaged in an aggressive physical therapy program emphasizing ROM, gait training, and strengthening.
If the patient has not achieved 90 degrees of flexion by 6 weeks, MUA is performed.
OUTCOMES
Include functional and prosthetic survivorship data, as applicable.
Table 1 summarizes the results of arthroscopic release with manipulation, open arthrolysis, and revision TKA for the treatment of stiffness.
Most of the literature suggests that reoperations for stiffness are associated with improvements in ROM, pain, and function, but that these gains are modest and in a certain percentage of patients, stiffness will recur.
An arthroscopic release seems most appropriate for select patients with well-fixed, appropriately positioned and rotated components.
Flexion contractures are particularly difficult to correct.
COMPLICATIONS
Recurrent stiffness
Extensor mechanism disruption (particularly patellar tendon avulsion)
Infection
Instability
Neurovascular injury
Deep venous thrombosis
REFERENCES
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