Evidence-based Considerations for Meniscus Repair Rehabilitation

Biomechanical studies have shown that the various meniscus tear patterns and their associated repair techniques respond differently when subjected to physiologic loading. For example, weight bearing across the knee helps reduce and compress vertical longitudinal and bucket-handle tears, which may improve healing rates following repair. In contrast, weight bearing causes displacement and distraction of radial, root, and complex tears, which likely decreases the chances of successful healing. As a result, accelerated rehabilitation protocols with early weight bearing and range of motion (ROM) have shown positive results in patients with vertical and more stable tear patterns. Lind and colleagues randomized 60 patients undergoing repair of unstable peripheral vertical meniscus lesions to either an accelerated or conservative postoperative rehabilitation plan. The accelerated plan consisted of 2 weeks of 0° to 90° ROM without a brace and touch-down weight bearing followed by unrestricted weight bearing and ROM. This group returned to running at 8 weeks and contact sports at 4 months. Compared with the restricted group, there were no differences in functional or subjective outcomes at 1 or 2 years. However, there is limited evidence to support these advanced protocols for more complex and unstable tear patterns. Kocabey and colleagues achieved positive results using a tear-specific rehabilitation protocol. Fifty-five patients undergoing a T-fix meniscal repair were stratified according to tear size. Patients with anteroposterior longitudinal meniscal tears less than 3 cm in length were full weight bearing following surgery but ROM was restricted to 0° to 90° for 3 weeks and 0° to 125° from 3 to 6 weeks. Patients with tears greater than 3 cm were immobilized in a knee brace for 3 weeks but allowed weight bearing. Patients were restricted to passive motion from 0° to 90° with a continuous passive motion (CPM) device. Between weeks 3 and 6, patients were allowed to progress to active knee flexion between 0° and 90°. In addition, patients progressed to 0° to 125° for weeks 6 to 8, after which all restrictions were terminated. Patients with complex and radial tears were further limited with respect to initial postoperative weight bearing and ROM (ie, non–weight bearing and no flexion >90° for 6 weeks). Ultimately, patients with longitudinal tears were allowed to return to sport at 3 months, whereas patients with complex and radial tears were allowed to return to sport between 4 and 5 months. The investigators reported that 96% of patients with isolated meniscus repair and 100% with combined anterior cruciate ligament (ACL) reconstruction and meniscus repair showed excellent outcomes. Given these findings, it follows that an ideal protocol must consider the tear pattern, location, and size; quality of the repaired tissue; the type and strength of repair construct; and any concomitant procedures (eg, ligament repair/construction, realignment osteotomy, cartilage restoration) that may have been performed.

The early postoperative period is crucial to protect the meniscal repair such that compression is maintained across the repair site. If the compressive forces across the repair site are lost, the odds of successful meniscal healing decrease significantly. Two main factors are at play with regard to compression at the repair site: (1) the strength and security of the fixation at the time of surgery, and (2) the weight bearing status postoperatively. The quality of the repair construct is under the control of the surgeon and every attempt should be made at anatomic reduction and fixation of the torn meniscus in order to optimize its healing potential and to restore normal knee biomechanics. There has been an evolution of fixation strategies to assist surgeons in achieving this goal. A myriad of all-inside, inside-out, outside-in, and novel suture passers and fixation devices are available for most tear patterns, including meniscal root and ramp lesions. Having a broad arsenal for meniscal repair can assist surgeons in achieving the goal of anatomic reduction and strong time-zero meniscus fixation. In addition, the weight-bearing status is determined both by surgeon preference and patient compliance. Early weight bearing can be helpful to provide compression and reduction in more stable tear patterns, and these patients should be allowed to weight bear as tolerated (WBAT) immediately following surgery. In contrast, weight bearing can create distractive forces for unstable tear patterns, specifically radial, complex, and posterior root tears, and thus these patients should be made non–weight bearing for a period of several weeks ( Fig. 1 ).

( A ) A 17-year-old boy with a complex lateral meniscus flap tear treated with an all-inside repair. This patient was limited to foot-flat 0% weight bearing for 6 weeks. ( B ) A 14-year-old female dancer who sustained a noncontact injury and presented with a bucket-handle medial meniscus tear that was treated with a hybrid all-inside and inside-out repair. This patient was allowed to WBAT immediately after surgery. ( C ) A lateral meniscus transosseous posterior root repair in a patient who was limited to foot-flat 0% weight bearing for 6 weeks. ( D ) A horizontal cleavage tear treated with all-inside circumferential stitch. This patient was allowed to WBAT immediately after surgery.

It is also important to consider the axial alignment of the patient before advancing weight-bearing status. Previous work has shown that patients with varus deformity are at higher risk of developing atraumatic medial meniscus tears. Therefore, patients with varus malalignment undergoing rehabilitation following a medial meniscus repair may benefit from a more conservation approach to progressive weight bearing. The same principles should be applied to those with valgus alignment undergoing a lateral meniscus repair because of the increased compressive loads in the lateral compartment. These select patients may also benefit from a medial or lateral unloader brace when initiating weight bearing postoperatively to reduce loads across the meniscus repair within the compartment at risk.

In addition to the postoperative weight-bearing status, knee ROM also needs to be carefully considered. It has been shown that immobilization following meniscal repair is detrimental to meniscal healing. Protected early ROM is important for healing and to reduce the risk of postsurgical arthrofibrosis. However, it is imperative to avoid deep flexion given that cadaveric studies have shown greater femorotibial contact pressures in higher degrees of knee flexion as opposed to full extension or low degrees of knee flexion. The progression toward high knee flexion angles during weight bearing leads to higher peak contact pressures, which may be detrimental to meniscal healing, particularly following radial and root repairs. However, these restrictions may not be required following fixation of more stable tear patterns (ie, vertical longitudinal tears). Extrapolating data from the knee cartilage restoration and repair literature, it seems that early gravity-assisted ROM (even past 90°) and/or use of CPM are likely safe and beneficial in the early postsurgical period. Progression to loaded deep-flexion activities should be avoided until meniscus healing is well underway (ie, 3 months) because of the increased loads and translation experienced by the menisci in higher degrees of knee flexion.

Blood Flow Restriction Therapy: A Novel Approach to Quadriceps Atrophy

It is well known that knee pain and effusion can lead to quadriceps dysfunction and atrophy; this is particularly true in the setting of a meniscal tear, both preoperatively and postoperatively. Furthermore, there is likely a correlation between the length of time a patient has a meniscal tear (ie, longer time with painful effusion) and the amount of quadriceps dysfunction and/or atrophy (ie, longer duration of quadriceps avoidance). It has been shown that the return of quadriceps function and strength in the setting of ACL injury and reconstruction is related to improved patient outcomes. However, it can be difficult to restore quadriceps muscle strength and size while protecting a meniscal repair. The American College of Sports Medicine recommends a resistance training load of 70% to 85% of the 1-repetition maximum (1RM) to promote muscle hypertrophy. It is often challenging or impossible for postoperative patients to achieve these loads early in the recovery process while protecting the meniscus, particularly in the setting of complex tear patterns and repairs that require early limitations in weight bearing and ROM. Blood flow restriction therapy (BFRT) has become a growing part of the preoperative and postoperative rehabilitation regimen to combat this difficult problem.

During a blood flow restriction session, a specialized blood pressure cuff is placed on the patient’s extremity ( Fig. 2 ). Most commonly, this is the operative extremity, but it may be used on other extremities as well. The specialized cuff measures the patient’s blood pressure and sets the cuff pressure at a specific level to prevent venous outflow from the patient’s limb, which ultimately results in the development of an anaerobic environment with subsequent release of growth factors. It is the release of these growth factors that promotes muscle hypertrophy. The beauty of BFRT is that it can stimulate an anaerobic environment using loads much less than the traditional 70% to 85% of 1RM, thus minimizing stresses to the meniscal repair. Most studies on BFR use loads near 30% of 1RM, with results showing significant increases in both muscle hypertrophy and strength. Although there are scant data on the use of BFR following meniscal repair, there are encouraging studies in the ACL reconstruction literature proving the safety and efficacy of BFRT. According to a recent meta-analysis, strength and muscle hypertrophy were significantly greater in the groups performing exercise with BFR 2 to 3 d/wk compared with those exercising 4 to 5 d/wk.

A patient undergoing a therapy session while wearing the blood flow restriction tourniquet.

In our practice, our physical therapists are certified in BFRT and use it in select patients with complex repairs requiring prolonged weight-bearing limitations. We also use this in our athletic population following standard or complex repairs to accelerate the return of quadriceps function and to help facilitate earlier return to sport. We are actively collecting prospective data on several populations using BFR for rehabilitation following ACL reconstruction (randomized controlled trial enrolling), meniscus repair, and cartilage restoration; and should have data on its efficacy for early quadriceps return and functional outcomes in the near future.