Gregory C. Fanelli, Justin D. Harris, Daniel J. Tomaszewski, and John A. Scanelli III
DEFINITION
Loss of motion is a generic term that can refer to a loss of flexion, extension, or both. It does not specifically imply a particular etiology.
Flexion contracture implies a loss of extension secondary to contracture or relative shortening of the posterior soft tissues (capsular or muscular).
Arthrofibrosis describes knee loss of motion (ie, flexion, extension, or both) caused by diffuse adhesions or fibrosis within a joint.
Ankylosis describes immobility of a joint, usually secondary to fibrous, cartilaginous, or bony overgrowth.
Knee loss of motion is a common and serious complication of knee ligament injury or reconstruction. Surgeon understanding of the pathogenesis, preventive measures, and surgical management of this condition is vital for optimum patient care.
ANATOMY
The knee has been described as a ginglymus (simple hingetype) articulation.
In actuality, knee motion is complex and requires at least six degrees of freedom (ie, translation in the anteroposterior, mediolateral, and tibial axial planes with rotational moments corresponding to abduction-adduction, flexion-extension, and internal-external rotation).
The knee joint consists of three independent articulations: the patellofemoral, medial tibiofemoral, and lateral tibiofemoral articulations.
Constraint of the knee joint is complex and dynamic. It depends on the position of the knee, the direction and nature of a given load, and the integrity of its bony and soft tissue restraints.
The knee joint is the largest in the body. Its capsular attachments extend from the suprapatellar pouch proximally to posteromedially and from the posterolateral recesses distally.
Fibrosis can occur anywhere within these confines and ultimately may lead to loss of motion.
Normal knee motion varies from person to person.
Most people achieve some degree of recurvatum in full extension, with men averaging 5 degrees and women averaging 6 degrees of hyperextension.
Normal knee flexion ranges from 140 degrees in men to 143 degrees in women.
Slight losses of flexion are much better tolerated than slight losses of extension.2,20 Full extension is required to allow quadriceps relaxation during the stance phase of gait. Small deficits in terminal flexion may go unnoticed by all but the elite athlete.
PATHOGENESIS
Loss of motion after a knee injury can vary, depending on patient predisposition, the extent and nature of the injury, the timing and technique of surgery, and postoperative management (Table 1).
Motion loss in an injured or reconstructed knee can be associated with any of a wide variety of conditions.
A complete understanding of the terminology associated with knee loss of motion is essential to diagnose and communicate the patient's condition appropriately (Table 2).12
Each area has its own pathoanatomy and relevant physical findings.
NATURAL HISTORY
Loss of knee motion, particularly extension, can have a tremendous effect on clinical outcomes and overall patient satisfaction.
Pressures across the patellofemoral joint during stance increase from 0 to 30% of body weight when comparing full extension to a 15-degree flexed position.20
These altered mechanics can lead to pain, apprehension regarding motion, and, ultimately, worsening stiffness. Aggressive intercession via a carefully directed physical therapy protocol or appropriate surgical intervention is essential.
PHYSICAL FINDINGS
Knee motion after ligament reconstruction must be monitored vigilantly.
Motion should be compared with the contralateral extremity.
Any loss of motion in the flexion or extension plane should be considered abnormal.
A complete examination of the knee is essential and can help determine the etiology.
Inspection
Swelling or erythema may indicate infection, reflex sympathetic dystrophy, or reinjury.
Palpation
Effusion may indicate infection or reinjury.
Allodynia may indicate reflex sympathetic dystrophy.
Crepitus may indicate fibrosis, soft tissue calcification, or an anterior cruciate ligament (ACL) nodule.
A “clunk” may indicate an ACL nodule.
Range of motion (ROM)
Extension loss may indicate posterior capsular contracture, infrapatellar contracture syndrome, medial collateral ligament (MCL) calcification, hamstring contracture, notch impingement, ACL nodule, or graft malposition or tension.
Loss of flexion may indicate quadriceps contracture, infrapatellar contracture syndrome, graft malposition or tension, patellar entrapment, or suprapatellar adhesions.
Loss of flexion and extension may indicate arthrofibrosis, infection, soft tissue calcification, infrapatellar contracture syndrome, or graft malposition or tension.
IMAGING AND DIAGNOSTIC STUDIES
Plain radiographs—including anteroposterior, lateral, sunrise, and tunnel views—are the essential first step in imaging.
Hardware failure, osteochondral defects, MCL calcifications, patellar height, patellofemoral alignment, and tunnel placement can be assessed with these images.
MRI can be obtained to more clearly evaluate the soft tissues.
The extent and nature of adhesions, graft position, graft failure, and the presence of an ACL nodule can be clarified by MRI.
DIFFERENTIAL DIAGNOSIS
Arthrofibrosis
ACL nodule
Graft malposition
Infection
Infrapatellar contracture syndrome
Muscle contracture
Reflex sympathetic dystrophy
NONOPERATIVE MANAGEMENT
Rest, ice and anti-inflammatory medications should be the first-line intervention for any knee with an acute process as found on physical examination: ie, an inflamed, warm, swollen knee with motion loss.
Controlled, guided physical therapy is an excellent tool to help regain motion.
Quadriceps strengthening, active ROM exercises, use of continuous passive motion machines, hanging weights, and extension bracing or casting may all have a role. Each intervention depends on the clinical picture and pathogenesis.
Our rehabilitation protocol for a multiple ligament knee reconstruction typically involves four phases (Table 3).
Manipulation under anesthesia has been used by some to improve postoperative motion.4
Manipulation should be done with caution, because the procedure itself can cause an inflammatory reaction and lead to further fibrosis.
SURGICAL MANAGEMENT
Failure to progress with nonoperative treatment is a general indication for operative management.
Identification of the primary cause of the knee stiffness is essential to maximize outcomes.
Indications for surgical intervention include:
Loss of flexion of 10 degrees or more
Extension deficits of 10 degrees or more
Failure to improve despite 2 months of intense therapy
The primary goal of operative treatment is restoration of normal knee motion without causing iatrogenic damage to the joint.
In both acute and chronic knee stiffness, resolution of the inflammatory phase of the condition is mandatory before proceeding with surgical intervention.
Epidural or regional anesthesia can be used to assist with postoperative pain control to allow more intensive physical therapy in the immediate postoperative period.
Millett et al10,13 have outlined a systematic nine-step evaluation of potential causes for knee loss of motion, all of which must be addressed whether surgical intervention is performed in an open fashion or arthroscopically.
Open Surgical Treatment
In severe cases of loss of motion of the knee, open releases may be indicated.
Indications for open débridement and soft tissue release typically include patients with severe arthrofibrosis or patients who have failed previously attempted arthroscopic releases.
Our general approach is to restore flexion by releasing capsular contractures, by lysing intra-articular fibrosis, and by mobilizing the extensor mechanism.
Extension is restored by addressing notch pathology, posterior capsular contractures, and anterior fibrosis.
Positioning
The patient is placed supine on the operating table.
A pneumatic tourniquet is placed high on the thigh over a cotton wrap. It is not routinely inflated.
Preoperative Planning
Examination under anesthesia is performed.
Flexion, extension, and patellar mobility should all be assessed preoperatively.
With the patient fully anesthetized, the hip should be flexed to 90 degrees.
Gravity should then be allowed to flex the knee. This reveals the true flexion limit.
With the hip extended, the heel should be supported; the extension limit is then measured.
Patellar mobility should then be documented with regard to superior–inferior glide, mediolateral glide, and patellar tilt.
Comparison to the normal, uninvolved knee is extremely useful.
TECHNIQUES
ARTHROSCOPIC EVALUATION
The affected limb is then prepped and draped in standard fashion.
A side post is utilized under the drapes along the lateral thigh.
All surgical landmarks and proposed incisions are then drawn on the skin with a surgical marker.
A surgical timeout is then performed, confirming the patient, the procedure, and the operative limb.
Perioperative antibiotics are administered within 30 minutes of the surgical incision.
In severely fibrotic knees, capsular distention using 120 to 180 mL of saline may be necessary to gain safe access to the knee joint without causing iatrogenic damage to the articular cartilage.
A standard superolateral inflow portal is then created, followed by an inferolateral viewing portal, and, lastly, by an inferomedial working portal.
Portals are interchanged as necessary, and additional arthroscopic surgical portals are established when necessary (TECH FIG 1).
Suprapatellar Pouch
In a normal knee, a view of the suprapatellar pouch should reveal the vastus intermedius rising off of the femoral shaft.
The suprapatellar pouch should extend 3 to 4 cm proximal to the superior pole of the patella.
TECH FIG 1 • Establishment of the arthroscopic superior medial and lateral patellar portals (A) and the inferior medial and lateral patellar portals (B).
Scarring in the suprapatellar pouch is the most common cause of loss of flexion and, in certain cases, may preclude safe passage of instruments between the femur and patella (TECH FIG 2).
Lateral or medial retinacular release, or both, may be necessary before suprapatellar pouch débridement can be done.
Dense fibrous tissue may make it difficult to visualize normal articular cartilage.
Using a combination of electrocautery, motorized shavers, arthroscopic knives, or heavy scissors, the suprapatellar pouch is reconstituted by performing aggressive releases.
Care must be employed to avoid damage to the overlying quadriceps tendon or surrounding articular cartilage.
Medial and Lateral Gutters
Adhesions in the gutters also are common causes of flexion loss.
Dense bands of fibrous tissue course between the femoral condyles and the medial and lateral retinaculi.
The surgeon should then clear all abnormal tissue, moving proximally to distally from the femur to the retinaculum.
The gutters should be débrided to the level of the tibial plateau, both medially and laterally.
Ninety degrees of knee flexion should be attainable at this point of the procedure.
Failure to reach 90 degrees of knee flexion at this point mandates further débridement of the suprapatellar pouch or medial–lateral gutters.
TECH FIG 2 • Arthroscopic view of arthrofibrosis in the suprapatellar pouch.
Anterior Interval
Débridement of the infrapatellar fat pad and pretibial recess is then performed (TECH FIG 3).
Care must be undertaken to avoid the intermeniscal ligament.
The release should proceed 1 cm distal to the level of the meniscus along the anterior tibial cortex.
Hemostasis is essential in the pretibial recess to avoid recurrent scarring of the infrapatellar fat pad.
Visualization in the anterior interval often can be difficult. A small, medial parapatellar tendon arthrotomy often is used to initiate débridement in the anteroinferior aspect of the knee.
Lateral and Medial Retinaculum
Using electrocautery, selective lateral and medial retinacular releases are performed.
This improves patellar mobility and increases the effective joint space in the knee.
Adequate release is achieved when the patella can be everted at least 45 degrees.
Intercondylar Notch
Scarring over the anterior aspect of the ACL, “cyclops” lesions, or graft impingement within the notch can all be addressed.
A notchplasty is performed if there is evidence of graft impingement as the knee nears maximal extension.
Cyclops lesions should be débrided and excised.
In severe cases, malpositioned cruciate grafts may require débridement or release to achieve full extension.
TECH FIG 3 • Arthroscopic débridement of the infrapatellar fat pad, and the pretibial recess.
Menisci
Normal menisci have significant anteroposterior excursion with knee motion.
In cases of knee stiffness, the menisci can become scarred in a posterior position during knee flexion, which will limit full extension.
A probe can be used to assess for meniscal mobility.
If anterior meniscal excursion is poor, a gutter should be created along the periphery of the meniscus from the midbody, working anteriorly until normal mobility is restored.
This should help achieve full extension, but a posterior capsular release may be necessary in severe cases.
Posterior Capsule
If full extension cannot be achieved after release of all the tissues just discussed, open posterior capsular release may be indicated.
Posteromedial and posterolateral approaches commonly are used.
The posteromedial approach uses an interval between the superficial MCL anteriorly and the pes anserine tendons posteriorly, revealing the underlying medial head of the gastrocnemius and the posterior oblique ligament.
The posterior oblique ligament is then released from its femoral attachment, and extension is reassessed.
If extension is still limited, a posterolateral release is necessary.
The lateral approach courses over the anterior aspect of the biceps tendon distally to the fibular head.
The short head of the biceps is reflected posteriorly, revealing the lateral head of the gastrocnemius, which often is intimately attached to the lateral capsule.
The capsule is then incised anterior to the gastrocnemius tendon, releasing the posterolateral capsule.
Care is taken to avoid the lateral collateral ligament, the popliteus tendon, and the popliteofibular ligament.
Open Surgical Treatment
Open Anterior Release
Positioning and examination under anesthesia are performed just as described in the arthroscopic section.
An anterior extensile approach to the knee is used.Previous vertical incisions can be used, or arthroscopic portal incisions may be extended (TECH FIG 4A).
The subcutaneous tissues are dissected sharply, and fullthickness flaps are raised medially over the extensor mechanism.
A medial parapatellar arthrotomy is then employed to gain access to the joint.
Care must be taken to protect the medial meniscus and the intermeniscal ligament (TECH FIG 4B).
A medial release is performed by subperiosteally dissecting the soft tissues off of the medial proximal tibia.
The release is extended posteriorly, and the deep MCL and semimembranosus are elevated to assist in mobilizing the tibia. The insertion of the superficial MCL must be protected.
Débridement of the medial and lateral gutters is then performed using a combination of finger dissection along with sharp excision of dense adhesions and fibrosis (TECH FIG 4C,D).
TECH FIG 4 • A. Anterior extensile exposure of the knee is used in the open surgical treatment of arthrofibrosis. B. Medial parapatellar arthrotomy is used to gain access to the knee joint. Note the severity of the intra-articular fibrous adhesions. C. Débridement of the medial and lateral gutters using a combination of sharp and blunt dissection. D. A large quantity of pathologic fibrous tissue was excised during the débridement.
TECH FIG 5 • Establishment of the pretibial recess. The patellar tendon is adherent to the proximal tibia, proximal to its normal insertion site. Establishment of the normal pretibial recess is essential to motion restoration.
Extensor Mechanism Release
The patellar tendon is dissected free from encasing fibrosis on all sides.
The infrapatellar fat pad is excised in its entirety. The insertion of the patellar tendon on the tibial tubercle must be protected (TECH FIG 5).
Adhesions between the quadriceps tendon and the distal femur must be released prior to patellar mobilization.
An inside-out lateral release is then employed, and the patella is then everted or translated laterally to assist with notch visualization.
Patellar tracking is then assessed throughout the entire ROM.
Notch Débridement
If full extension is still unattainable at this point of the procedure, graft impingement and malposition must be addressed.
Residual cyclops lesions are débrided.
It may be necessary to excise anteriorly positioned ACL grafts, with removal of involved hardware (TECH FIG 6A).
Posterior capsular contractures can be released by peeling the capsule off the posterior aspect of the femoral condyles.
The PCL is then evaluated for impingement and is released if found to be a block to extension.
Finally, a posterior capsular release from the proximal tibia may be needed if full extension has not yet been achieved (TECH FIG 6B,C).
Closure
Meticulous hemostasis is achieved using electrocautery following deflation of the tourniquet.
A medium Hemovac drain is placed intra-articularly to reduce postoperative hematoma formation and is left in place for 1 to 2 days.
The medial parapatellar arthrotomy is closed with absorbable suture if it can be performed without significant tension on the extensor mechanism.
The subcutaneous tissues and skin are then closed in standard fashion, and compressive dressings are applied.
The knee is placed in a hinged knee brace and locked if necessary.
TECH FIG 6 • A. Intercondylar notch débridement is performed to address the issue of graft impingement and malpositioned grafts. B,C. Intraoperative range of motion achieved after open surgical débridement for severe posttraumatic arthrofibrosis. Preoperative range of motion was 10 to 30 degrees of knee flexion.
POSTOPERATIVE CARE
If epidural anesthesia or regional blocks were used during the operative procedure, patients may benefit by continuing their use in the postoperative period. Additionally, intraarticular injections of bupivacaine combined with morphine given in the operating room can assist with postoperative pain control.
Adequate pain relief is essential for the patient to tolerate the immediate postoperative rehabilitation.
Continuous passive motion (CPM) is used in the immediate postoperative period to assist with knee ROM.
When patients are not using the CPM machine, they are placed in a hinged knee brace locked in extension.
Home CPM usually is needed for 2 to 3 weeks.
Outpatient physical therapy also is implemented early in the postoperative period.
Gentle ROM exercises are encouraged initially, so as not to exacerbate the inflammatory process that originally created the knee loss of motion. Additionally, articular cartilage may be prone to injury by forced motion or excessive activity.
Prone hangs, knee sags, patellar mobilization, and active quadriceps contraction are emphasized to maintain full extension.
More aggressive strengthening exercises are begun as the patient continues to progress and improve.
Multiple modalities are implemented to minimize postoperative swelling and pain.
A cryotherapy device is applied in the recovery room and used in both the inpatient and outpatient settings.
Nonsteroidal anti-inflammatory medications (NSAIDs) or short courses of oral corticosteroids can be given to reduce inflammation.
Compressive dressings are used.
Knee aspiration may be necessary for effusions that are large enough to cause pain, inhibit quadriceps activity, or limit ROM.
In severe cases, it may be necessary to restrict weight bearing postoperatively to protect compromised articular cartilage.
Initiation of weight-bearing activities is at the surgeon's discretion.
Extension bracing often can be discontinued once patients have full return of quadriceps function.
OUTCOMES
Nonsurgical Results
Few studies have been written regarding nonoperative management of knee loss of motion.
Noyes and associates11 reported on 18 patients who did not regain full motion following ACL reconstruction despite implementation of an early active and passive motion protocol.
Six knees were treated with serial extension casts, nine had early gentle manipulation under anesthesia, and three required arthroscopic lysis of adhesions.
Thirteen of the 15 patients treated nonsurgically regained full ROM of the knee.
In a separate study, Noyes et al15 prospectively evaluated 443 knees and reported that 23 developed arthrofibrosis following ACL reconstruction.
Twenty knees (87%) were treated successfully using manipulation under anesthesia, extension casting, and continuous epidural anesthesia.
The authors stated that nonsurgical management often can be successful if initiated early.
Loss of knee motion that is present more than 3 months following ligament reconstruction surgery is less likely to respond to nonsurgical means.
Dodds et al4 evaluated the results of knee manipulations performed for loss of motion in 42 knees that previously had undergone intra-articular ACL reconstruction.
The average time from reconstruction to manipulation was 7 months.
Ten knees had concomitant arthroscopic débridement.
Average flexion increased from 95 to 136 degrees, and extension improved from 11 to 3 degrees.
No complications were reported.
Arthroscopic Results
Most studies in the literature pertaining to knee loss of motion contain a mixed group of patients with varying degrees of severity, chronicity, and etiology. Results should be interpreted based on the specific variant of motion loss.
ACL nodul.
The term “cyclops syndrome” was coined by Jackson and Schaefer9 after reviewing 13 patients with loss of knee extension after ACL reconstruction.
All patients were treated with arthroscopic débridement and manipulation. Patients gained an additional 10 degrees of extension and 27 degrees of flexion immediately postoperatively.
Motion continued to improve with longer follow-up.
Six of the patients required more than one procedure to achieve these results.
Marzo et al11 reported on 21 patients with restricted knee extension following ACL reconstruction.
All patients had a cyclops lesion at surgery and were treated with arthroscopic débridement, with 10 patients requiring an additional notchplasty for graft impingement.
All patients had good results, with an average extension gain of 8 degrees leaving them with an average final extension deficit of 3 degrees.
Fisher and Shelbourne5 reported on 42 patients who required arthroscopic débridement for symptomatic extension loss following ACL reconstruction.
Both pain relief and ROM improved postoperatively.
No complications were reported.
Diffuse arthrofibrosi.
Multiple studies have documented successful treatment of diffuse intra-articular arthrofibrosis with arthroscopic débridement and release.1,3,17,24–26
Shelbourne and Johnson22 reported on nine consecutive patients with symptomatic knee loss of motion following ACL surgery.
Eight of the nine patients underwent ACL reconstruction within 2 weeks of the initial injury and were immobilized in flexion postoperatively.
The patients underwent arthroscopic débridement of adhesions in the superior patellar pouch, medial and lateral gutters, and in the anterior interval. Notchplasties also were performed followed by manipulations to regain flexion. Extension casting and physical therapy were used postoperatively.
At an average of 31 months follow-up, patients had gained 23 degrees of extension and 18 degrees of flexion. Eight of the nine patients returned to sports.
Hasan and associates8 reviewed 17 knees with symptomatic extension deficits following ACL reconstruction.
All knees were treated with arthroscopic débridement of intra-articular adhesions with excision of cyclops lesions and revision notchplasties.
Postoperative ROM yielded 7and 8-degree improvements in extension and flexion, respectively.
Harner and colleagues7 reviewed 21 of 27 patients who developed motion deficits following ACL reconstruction.
Fourteen of the patients were successfully treated arthroscopically, although three of those required a second procedure.
Six of the knees underwent formal open débridement for more severe intraand extra-articular adhesions.
Sixty-seven percent of the patients had a good or excellent result at final follow-up.
Open Results
Open débridement and lysis of adhesions are indicated in cases of severe knee loss of motion, infrapatellar contracture syndrome, and failed arthroscopic intervention.
Infrapatellar Contracture Syndrome
Paulos et al18 described infrapatellar contracture syndrome (IPCS) as an exaggerated pathologic fibrous hyperplasia of the anterior soft tissues of the knee.
Patients with this condition presented with loss of knee flexion and extension, patellar entrapment, and patella infera. The authors recommended open débridement in cases with extra-articular involvement.
Aggressive rehabilitation was done postoperatively.
Patients gained an average of 12 degrees of extension and 35 degrees of flexion at final follow-up.
Eighty percent of patients had signs and symptoms of patellofemoral arthrosis, however, with 16% of patients demonstrating patella baja.
A long-term follow-up study of IPCS reported on 75 patients who had undergone previous surgical intervention.
Depending on the severity of patellar involvement, arthroscopic and open releases were performed.19 In cases of patella infera, DeLee tibial tubercle osteotomies were performed.
Significant gains in ROM were achieved, but numerous patients required revision lysis of adhesions and manipulations.
The authors concluded that the longer the knee was without acceptable motion, the more likely the patient was to have a poor final outcome.
Richmond and Al Assal21 reported on arthroscopic treatment of IPCS. Their results revealed a total increase in knee ROM of 45 degrees in 12 patients with that condition.
Severe and revision case.
Millett et al13 retrospectively reviewed eight patients who had undergone an open débridement and soft tissue release for severe knee loss of motion.
All patients had failed previous arthroscopic intervention. The average arc of motion preoperatively was 62.5 degrees.
At final follow-up, the average motion had increased to 124 degrees.
Patient satisfaction scores were high, but there was a significant incidence of patellofemoral arthritis.
The authors concluded that an aggressive open release is a reasonable option for stiff knees that are recalcitrant to less invasive procedures.
A recent study detailed a mini-invasive extra-articular quadricepsplasty followed by an intra-articular arthroscopic lysis of adhesions for severe cases of knee arthrofibrosis.27
Twenty-two patients were treated with the aforementioned technique, in which a five-stage quadricepsplasty is performed to regain knee flexion. Knee arthroscopy was then performed to remove any intra-articular adhesions and to address pathology within the notch and the anterior interval.
At 44 months of follow-up, the average maximum degree of flexion had increased from 27 to 115 degrees.
Complications were rare: one superficial wound infection and one persistent 15-degree extension lag were reported.
COMPLICATIONS
The primary complication of surgical intervention for knee loss of motion is recurrence of knee stiffness.
Rates of reoperation following arthroscopic débridement range from 6% to 43%.5,24,25
Failure of surgical treatment is directly proportional to the severity of the preoperative stiffness.
The more invasive the procedure necessary to regain full knee motion, the higher is the risk of potential complications.
Other complications related to arthroscopic or open débridement and release include the following:
Skin tearing or necrosis
Wound dehiscence
Postoperative infection
Septic arthritis
Neurovascular injury
Extensor mechanism disruption
Hemarthrosis
Patellofemoral pain syndrome
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