Arthrofibrosis of the knee

                                   Arthrofibrosis of the knee

                                          Dr KS Dhillon

What is arthrofibrosis of the knee?

Spraque et al [1] were the first to describe knee arthrofibrosis in 1982. Arthrofibrosis refers to the development of excessive fibrotic tissue or adhesions within and around a joint which leads to limitation of movements of the joint. In the knee, the adhesions occur anteriorly in the infrapatellar fat pad, the pretibial recess, the suprapatellar pouch, medial and lateral gutters, posteromedial and posterolateral capsule. The clinical spectrum of this varies widely, ranging from localized to diffuse involvement of all compartments of the knee and of the extra-articular soft tissues around the knee.

Etiology of knee arthrofibrosis

There are several causes of knee arthrofibrosis and these include:

1.Soft-tissue Injury

The severity of soft-tissue injury, multi-ligamentous injury, severity of bony injury and dislocations of the knee, all play a role in the pathogenesis of arthrofibrosis.

2.Infection

Knee infections lead to the production of intraarticular inflammatory mediators which in turn produce synovitis and toxic degeneration of the articular surface. Local cytokine activation leads to fibrous scar formation.

3.Knee joint immobilization

Knee immobilization for ligament and bony injury as well as immobilization following knee surgery is a well-established risk factor for arthrofibrosis.

4.Timing of Surgery

Acute knee injuries need to be treated on admission to the hospital. Reconstructive surgery should be delayed until recovery from the acute injury has occurred. Timing of reconstructive surgery of the knee remains controversial. Majority of the authors recommend a delayed reconstruction of knee ligaments at 3 weeks. This delayed allows time for soft-tissue healing, resumption of full ROM, and improved strength. Reconstruction of knee ligament in the acute phase is associated with an increased incidence of arthrofibrosis [2,3,4].

5.Extra-articular and intraarticular procedures

Open arthrotomy and periarticular operative procedures such as collateral ligament repair as well as capsular surgery are known to cause arthrofibrosis. Multiple ligament reconstruction of the knee is also a known risk factor for arthrofibrosis. Graft malposition during ligament reconstruction can also lead to arthrofibrosis.

6.Genetic risk factors

Some patients develop arthrofibrosis despite efforts to reduce or eliminate the aforementioned risk factors. This has led some researchers to believe that there may be some genetic predisposition to arthrofibrosis after injury.

7.Complex regional pain syndrome

Complex regional pain syndrome also known as reflex sympathetic dystrophy inhibits effective patient participation in proper postoperative rehabilitation. As a result of the pain, quadriceps inhibition occurs leading to muscle atrophy and reduced joint mobility which in turn leads to arthrofibrosis.

Pathophysiology of arthrofibrosis

Locally acting growth factors and cytokines signals, control tissue organization and homeostasis in the human body. The cytokines coordinate cell growth, differentiation, and programmed cell death. This is done through constant signals which are sent between local cells (paracrine) and among themselves (autocrine). Platelets release transforming growth factor-β (TGF-β) and this growth factor plays an important role in tissue repair [5]. At the site of injury, the growth factor
initiates a series of events that result in the production of extracellular matrix proteins and protease inhibitors. Proteolytic enzyme production is also inhibited. An increase in the concentration of extracellular matrix at the site of injury results in TGF-β feedback inhibition. Excessive expression of TGF-β results in progressive deposition of matrix and tissue fibrosis [6].

Clinical presentation

Patients with arthrofibrosis of the knee can present with knee stiffness, pain, limping, warmth, swelling, crepitus, and/or weakness [7]. Loss of motion is the main symptom of knee arthrofibrosis. There can be a loss of flexion, loss of extension or loss of both flexion and extension.
Shelbourne et al [8] described a classification system based on the pattern of knee stiffness.

• Type I. Patients have normal flexion and less than 10-degree extension loss.
• Type II. Patients have normal flexion and more than10-degree extension loss.
• Type III. Patients have more than a 10-degree extension loss and a more than a 25-degree flexion loss with patella tightness.
• Type IV. Patients have an extension loss of more than 10 degrees and 30 degrees or more loss of flexion with patella infera with marked patella tightness.

Del Pizzo et al [9] classified knee arthrofibrosis based on deviation from full extension and amount of flexion present:

• Mild: less than 5° loss of extension, flexion more than 110° 
• Moderate: 5°–10° loss of extension, flexion between 90°–100° 
• Severe: More than 10° loss of extension, flexion less than 90° 

Paulos et al [10] were the first to describe infrapatellar contraction syndrome (IPCS). In patients with IPCS, there is a significant reduction of both flexion (>25°) and extension (>10°) with a decrease in patellar mobility which is characterized as patellar entrapment. IPCS is caused either by an exaggerated pathologic fibrous hyperplasia of the anterior soft tissues of the knee or certain risk factors associated with knee surgery such as poor graft isometry, joint immobilization, and muscle weakness.

Paulos et al [10] divided patients with IPCS into three stages namely the prodromal, active, and residual stages.

In the prodromal stage, there is periarticular inflammation, oedema, weakness of the quadriceps, extension lag, painful movements and tenderness over the patellar tendon with decreased patellar excursion.

In the active stage, there is a marked decrease in patellar mobility, severe quadriceps atrophy, worsening knee motion, and induration of the fat pad with a rigid patellar tendon.

In the residual stage, the peripatellar and retinacular tissues are more
supple than in the active stage and there is marked quadriceps atrophy with loss of knee flexion and extension.

The diagnosis of joint arthrofibrosis is clinical. It is made after excluding other causes of knee stiffness. There are no radiological investigations which can confirm the diagnosis. Arthroscopy can confirm the diagnosis but it is not warranted for diagnosis. Tissue biopsy is also not required to make the diagnosis.

The average genu recurvatum is 5 degrees for males and 6 degrees for females, and the average knee flexion is 140 degrees for males and 143 degrees for females [11]. Studies have shown that 67 degrees of knee flexion is required in the swing phase of walking, 83 degrees to ascend stairs, 90 degrees to descend stairs, and 93 degrees to rise from a standard chair [12]. Loss of knee flexion is usually better tolerated than the loss of knee extension. Even small discrepancies in extension are associated with increased energy consumption during gait and extension loss can cause undue strain on the quadriceps musculature and the patellofemoral joint [13].

Ligament reconstruction is probably the most common cause of arthrofibrosis. The incidence of knee stiffness after ligament reconstruction varies between 4% to 35% [14]. Shapiro and Freedman [15] reported a 57% incidence of knee motion loss in patients undergoing combined anterior cruciate ligament and posterior cruciate ligament reconstructions.

IPCS is the most serious form of arthrofibrosis which can complicate ligament reconstructions. The natural history of an anterior cruciate ligament-deficient knee is much more benign than the natural history of a knee that develops IPCS [10].

Treatment of knee arthrofibrosis

1.Immediate Postoperative Motion

Following knee ligament injury and knee surgery, all efforts must be directed at prevention arthrofibrosis and consequent loss of motion. Prolonged immobilization should be avoided and immediate active and passive range of motion exercises should be started.

Noyes et al [16] was able to show a good outcome with postoperative immediate knee motion and early intervention in patients who had ACL reconstruction. In a prospective study, 93% (413 of 443) of their patients regained full ROM (0º to 135º) with the use of active and passive knee exercises in the immediate postoperative period. Of the 30 patients who did not regain full range of movements, 23 were subjected to a postoperative treatment regime which included hyperflexion and hyperextension exercises and serial extension casting. Eight patients who did not respond to cryotherapy, NSAIDs, elevation, and compression were given oral steroids. In refractory cases, manipulation under anesthesia, physical therapy, and arthroscopic débridement were performed. At the end of treatment, 98% of their patients regained full knee motion, 2% had minor extension limitations, less than 1% required arthroscopic release of adhesions, and no patient developed permanent arthrofibrosis.

2.Postoperative Knee Bracing

A rehabilitation brace is commonly used after ACL reconstruction although its use is controversial. Majority of the surgeons use a brace for about 4 weeks after ACL reconstruction [17].

Melegati et al [18] carried out a prospective study to assess the role of the rehabilitation brace in restoring knee extension after anterior cruciate ligament reconstruction. They compared the outcome in two groups of patients. In one group the knee was braced from 0° to 90° and in the other group the knee was locked in full extension during the first week after ACL reconstruction. They found that patients who were braced in full extension for the first week postoperatively had a lower heel-height
differences at 4 and 8-week followup as compared to patients whose brace was unlocked twice daily for physiotherapy.

Mikkelsen et al [19] in a randomized prospective study showed that patients braced in 5 degrees hyperextension had less extension deficits as compared to patients whose knee was immobilized in full extension (0°) after ACL reconstruction. The outcome was measured 3 months after the surgery. The authors concluded that the use of a knee brace in hyperextension for at least 3 weeks after ACL reconstruction is an effective way of preventing postoperative extension loss.

3.Manipulation of knee under anesthesia

Dodds et al [20] reported the results of knee manipulations in 42 knees which had persistent flexion or extension deficits after ACL reconstruction. The manipulation was done at an average of 7 months (range, 3 to 14 months) following the reconstruction and the average follow up was 26 months (range, 6 to 56 months). After manipulation, the average flexion was increased from 95 degrees to 136 degrees and average extension from 11 degrees to 3 degrees. The outcome after manipulation was proportional to the severity of extension loss before manipulation. Patients with greater extension deficits achieved less overall final extension. They were able to achieve improvement in both flexion and extension in 86% of the knees. The authors of this study recommended manipulation within 12 weeks of ACL reconstruction. There are other authors who recommend manipulation within 4 to 12 weeks of reconstruction. Overaggressive and significant delay in manipulation can result in complications such as chondral damage, distal femur or patella fracture, patellar tendon rupture, quadriceps myositis ossificans and ossification of the MCL.

Consensus has been reached that MUA should be carried out between three and six months post-operatively and MUA is not indicated after 6 months [21].

4. Surgical treatment

A.Arthroscopic treatment

Arthroscopic debridement or arthrolysis is often successful in treating arthrofibrosis. The procedure can be carried out on an outpatient basis. A careful and thorough inspection of all compartments is carried out.

First, the suprapatellar pouch is cleared of adhesions followed with the medial and lateral gutters. The infrapatellar fat pad is then debrided and the recess between the patellar tendon and anterior tibia be reestablished.

In patients with excessive scarring and patellar entrapment, the medial and lateral retinacula are released.

In patients with limitation of extension clearance of the notch and notchplasty will be necessary. In some patients with limitation of extension, posteromedial and posterolateral capsular release may be necessary.

Aglietti et al [22] carried out a prospective study of 31 knee arthrolysis which were performed for loss of motion after anterior cruciate ligament reconstruction. The arthrolysis was carried out at an average of 10.6 months after the reconstruction (range 4-25 months). Twenty-one knees had arthroscopic and 10 had open surgery. In most knees suprapatellar, medial, and lateral gutter adhesions were removed and in 7 knees posteromedial and/or posterolateral capsulotomy was necessary. The ACL graft was nonfunctional and malpositioned in 19 knees.

The average follow up after arthrolysis was 3.5 years (range 1.5-7). Satisfactory outcome was obtained in only 37% of the knees. The authors found that arthrolysis performed within 8 months from index operation had a better outcome.

Cosgarea et al [23] carried out a retrospective analysis of 43 knees in 37 patients who had previous ligament surgery and developed postoperative arthrofibrosis. The average follow up was 3.6 years. Arthrolysis was carried out when there was flexion or extension deficits of equal to or more than 10 degrees or when motion failed to improve despite 2 months of intense therapy. Though flexion improved from 83% to 97% of the contralateral side and extension deficits improved from 14 degrees to 3 degrees, only 62% achieved satisfactory functional results. They found that lysis carried out sooner then 6 months had a better outcome.

Fisher et al [24] reported good outcome of arthroscopic excision of abundant tissue in the anterior tibiofemoral joint which caused an extension block after open ACL reconstruction. They had forty-two patients in their series and all patients had marked improvements in function and symptoms especially in activity-related anterior knee pain, crepitus at terminal extension, and knee stiffness.
Klein et al [25] reported the outcome of arthroscopic management of postoperative arthrofibrosis in 46 knees. The gain in range of motion was excellent in 54.5%, good in 21.7%, and fair and poor in 23.8%. Reduction of pain occurred in 80.4% of the patients. Patient satisfaction was excellent or good in 56.5%, fair in 39.1% and poor in 4.3%of the patients.

B.Open Debridement and Soft Tissue Release

Open debridement and soft tissue release is sometimes required in patients with severe scarring and in patients who have failed less-invasive approaches. Open surgery is usually required in patients with chronic motion problems who have long-standing extension deficits and generalized arthrofibrosis. In such patients, open surgery is usually a salvage procedure [26].

When extensive extra-articular calcification is present, open excision has to be carried out to restore knee motion. When extensive intra-articular fibrosis is present an anteromedial approach is used to completely debride all fibrous scar tissue anteriorly and posteriorly in the joint. Sometimes lateral retinacular release is needed to mobilize the patella. Following the surgery meticulous hemostasis has to be achieved to prevent a postoperative hematoma, which can lead to arthrofibrosis.

Millett et al [26] carried out a retrospective review of eight knees in 8 patients who had open debridement soft tissue release for extensive intraarticular and periarticular fibrosis of the knee. The average preoperative range of motion was 62.5° (flexion 81°, loss of extension 18.8°). The motion improved to an average of 124° after surgery. The average flexion improved from 81° to 125° and the loss of extension improved from 18.8° to 1.25°. Functional outcome was good and patient satisfaction was high.

Lobenhoffer et al [27] carried out a prospective study of 24 patients who were treated with arthroscopic arthrolysis and open posterior capsulotomy for flexion contractures of the knee. Twenty-one patients were available for review with a mean follow-up of 18 months (range 6–38 months). The mean preoperative extension deficit was 17° (range 10–30°). The postoperative extension improved to a mean value of 2°. None of the patients had more than 5° of extension deficit at follow-up. The knee function improved significantly with a Lysholm Score 62 preoperatively and 88 postoperatively 88 and the Tegner Scale 2.2 preoperatively and 4.0 postoperatively.

Tardy et al [28] carried out a retrospective study to assess the outcome arthroscopic anterior debridement and open posterior medial and lateral capsular release in twelve patients who presented with a chronic flexion contracture of 10° or more after ACL reconstruction. The average follow-up period was 38months (range 6 to 90 months). All patients except one (93%) achieved complete extension. Only one patient (7%) had a residual postoperative flexion deformity of five degrees. The range of motion improved significantly after arthrolysis. There were no postoperative complications. The post-operative objective IKDC scores, subjective IKDC scores, Knee injury and Osteoarthritis Outcome Score (KOOS), pain score, symptoms scores, ADL scores, sports activities scores and quality of life scores all improved. The mean patients' satisfaction was 9.25±0.6 (SD) out of 10 after arthrolysis.

The authors concluded that open posterior release with both posteromedial and posterolateral approaches is a safe and efficient procedure in patients with persistent flexion contracture.
Wierer et al [29] carried out a study to evaluate the efficiency of an arthroscopic posterior capsule release for the treatment of persistent knee extension deficits following ACL reconstruction. The study included 10 patients with knee flexion contracture who had arthroscopic debridement and arthroscopic posterior capsular release.

The median follow-up period was 25months (range: 14 to 69months). The median preoperative extension deficit was 15° (range: 10 to 20°) and the median postoperative extension deficit was one degree (range: 0 to five degrees). The median Lysholm score improved from 52 (range: 32 to 67) to 92 (range: 84 to 100) postoperatively. The median Tegner Activity Level improved from three to six postoperatively. The median VAS status for pain decreased from five to one. There were no postoperative complications.

The authors concluded that arthroscopic posterior capsulotomy is a safe and effective procedure for treatment of knee flexion contractures.

Conclusion

Arthrofibrosis, the formation of extra and intra-articular excessive fibrotic tissue can result from knee injury, infection, extra and intra-articular surgical procedures, and joint immobilization.
Arthrofibrosis can present with knee stiffness, pain, limping, warmth, swelling, crepitus, and/or weakness. Loss of motion remains the main symptom of knee arthrofibrosis. Several classification systems for arthrofibrosis based on the pattern of knee stiffness are available.
Every effort should be taken to prevent arthrofibrosis because loss of knee movements especially extension can be very disabling. Several treatment options are available including knee mobilization exercises, bracing and manipulation of the joint under anesthesia. Failure of noninvasive treatment will warrant surgical treatment which includes arthroscopic or open arthrolysis and soft tissue release. The outcome of treatment is variable. Some of the older studies reported outcome of treatment which was not so good but some newer studies show a much better outcome of treatment.

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