Variable Guidelines for Pediatric Medial Patellofemoral Ligament Reconstruction Rehabilitation Exists Across PRiSM Member Organizations

Abstract

Medial patellofemoral ligament (MPFL) reconstruction, typically used to restore stability to the patellofemoral joint after dislocation, often requires extensive rehabilitation to address acute impairment related to surgical intervention and also underlying non-anatomical deficits that may have contributed to the index injury. Rehabilitation guidelines, including objective functional performance assessment criteria, are lacking in the literature. We sought to summarize the clinical guidelines for rehabilitation and return to activity assessment after MPFL reconstruction as advocated by the member organizations of the Pediatric Research in Sports Medicine (PRiSM) Patellofemoral Research Interest Group (PF-RIG). We obtained and reviewed MPFL rehabilitation guidelines from 11 member organizations of the PRiSM PF-RIG, extracting information on weight-bearing advancement, bracing, use of supplemental strengthening modalities, and any objective criteria for advancing rehabilitation phases. We found highly variable agreement among guideline parameters at each treatment stage, with time-based criteria most widely used for early progression. Although functional metrics like strength or movement tests were more widely used in later phases of rehabilitation, there was substantial variation in testing mode and level of acceptable performance. Our review found that significant variability exists in current practice among PRiSM and PF-RIG member institutions regarding rehabilitation standards after MPFL reconstruction. Although we found broad consensus that objective strength or performance criteria should be employed to establish a better framework for clinical decision-making, most current guidelines lack standardization and sufficient detail to guide ideal clinical practice.

Introduction

Patellofemoral instability (PFI) is a common condition among adolescents, with an incidence that is 6 times higher in 10-to-17-year-olds than in the general population [23]. The pathophysiology is multifactorial, involving abnormalities in skeletal anatomy, ligamentous laxity, lower extremity biomechanics, isolated deficits in gluteal or quadriceps strength, and neuromuscular control [4,17]. Although primary rehabilitation is utilized in most patients after first-time dislocation, recurrent PFI serves as a relative indication for surgical management. Although a variety of bony and soft tissue surgical techniques exist in the operative management of PFI, the most commonly utilized is medial patellofemoral ligament (MPFL) reconstruction [9].

Medial patellofemoral ligament reconstruction is typically associated with extensive rehabilitation to address acute impairments related to surgical intervention and underlying non-anatomical deficits that may have contributed to the patient’s risk of index injury. Although MPFL reconstruction is often considered highly successful, with low reports of reinjury after surgery [12,15,19,21], a recent systematic review found that only 68% of patients were able to return to their previous level of sports participation [18]. In addition, many patients continue to express fear of repeat dislocations, lack of confidence in their knee, and activity avoidance after surgery [10,11]. Thus, although protective against reinjury, MPFL reconstruction may not be adequate to yield optimal patient outcomes.

The use of standardized rehabilitation guidelines and return to sports (RTS) testing criteria have been extensively studied in patients recovering from anterior cruciate ligament (ACL) reconstruction and shown to identify those at risk of poor outcomes, including inability to RTS and the risk of repeat injury [7]. Employing similar standards with patients recovering from MPFL reconstruction may improve outcomes. Unfortunately, rehabilitation guidelines, including objective functional performance assessment criteria, are lacking in the literature. A recent systematic review by Zaman and colleagues found that the majority of RTS decisions in the literature utilized time-based criteria only; just 19% of articles indicated that other means of subjective or objective criteria informed RTS decisions [24]. Identifying the tests or measures practitioners use to make informed rehabilitation and activity progression determinations is important to developing structured guidelines to assist clinical decision making with this population. The purpose of this study was thus to summarize the clinical guidelines for rehabilitation and RTS assessment after MPFL reconstruction among Pediatric Research in Sports Medicine (PRiSM) Society Patellofemoral Research Interest Group (PF-RIG) organizations.

Methods

We obtained and reviewed MPFL reconstruction rehabilitation guidelines from PRiSM PF-RIG member organizations. Each organization was contacted verbally or electronically and asked to participate in this study by uploading their current rehabilitation guidelines for MPFL reconstruction to a centralized storage folder. Guidelines including restrictions related to concurrent bony procedures such as tibial tubercle osteotomy were excluded. Physical therapist members of the study team (E.G., J.H., J.M., J.A.) reviewed each guideline independently and extracted relevant information pertaining to weight-bearing advancement, bracing, and objective criteria utilized to determine readiness for advancing rehabilitation phases (ie, discontinue bracing and assistive devices, return to running, and RTS). For each rehabilitation component, the proportion of guidelines that included that component was calculated. Time of initiation (median and range) was reported, and descriptive statistics were utilized to summarize these variables.

Results

Rehabilitation guidelines for MPFL reconstruction were available for 11 (85%) of the 13 PRiSM PF-RIG member organizations. One institution reported not having a structured postoperative guideline in place, whereas another used the set of another member organization. Early recovery temporal parameters are summarized in Fig. 1. Late recovery strength and functional metrics are summarized in Figs. 2 and 3, respectively.

Fig. 1.

PRiSM PF-RIG MPFL guideline criteria: weight-bearing status, bracing, and range of motion. MPFL Medial patellofemoral ligament, PF-RIG Patellofemoral Research Interest Group, PRiSM Pediatric Research in Sports Medicine.

Fig. 2.

PRiSM PF-RIG MPFL guideline strength criteria: progression for return to impact activity and return to play 1. MPFL Medial patellofemoral ligament, LSI Limb Symmetry Index, PF-RIG Patellofemoral Research Interest Group, PRiSM Pediatric Research in Sports Medicine.

Fig. 3.

PRiSM PF-RIG MPFL guideline functional criteria: progression for return to impact activity and return to play. MPFL Medial patellofemoral ligament, PF-RIG Patellofemoral Research Interest Group, PRiSM Pediatric Research in Sports Medicine.

Early Recovery

Immediate weight-bearing as tolerated was allowed in 27% (n = 3) of guidelines, whereas most others restricted weight-bearing to toe-touch (36%, n = 4) or partial (36%, n = 4). Three institutions (27%) had no restrictions on knee range of motion (ROM), permitting full ROM to patient tolerance immediately postoperatively. Of the remaining institutions, the course of knee ROM was highly variable with the majority of guidelines allowing for unrestricted knee ROM beginning postop week 6 (n = 5) with a range of 4 to 9 weeks. Ten out of 11 (91%) guidelines recommended the use of postoperative bracing after MFPL reconstruction. The duration of bracing varied with the majority discontinuing the use of bracing at post-op week 6 (n = 7), whereas others favored longer brace use of 7 weeks (n = 1), 8 weeks (n = 1), or 12 weeks (n = 1).

Progression to Running/Light Impact

All guidelines (100%) indicated specific time criteria to begin progression to jogging, with a median time of 12 weeks (n = 8) and a range from 10 to 20 weeks. Seven (64%) of the guidelines listed specific objective criteria to begin jogging. Non-specific assessment of functional movements was indicated by 4 guidelines, most requiring “good quad control” or “stable patella” in a single-leg squat. One guideline recommended an International Knee Documentation Committee (IKDC) global rating of function >8 to begin jogging.

Return to Sports Progression

Six out of 11 (55%) guidelines specified time criteria to begin to RTS, with most (n = 4) indicating 24 weeks and others ranging from 12 to 28 weeks. Strength criteria were stated in 4 (36%) guidelines. Assessment of movement quality was mentioned in 5 guidelines. However, most institutions did not include specific methodology to evaluate this construct, instead stating “good neuromuscular control” as the criterion. Nine out of 11 guidelines described a specific timeframe for unrestricted RTS, with a range of 16 to 36 weeks and the majority (n = 4) citing 24 weeks. Objective strength or performance criteria were included in 8 (73%) of the guidelines. Regarding muscle strength, 6 guidelines (55%) had some type of strength criteria. Three guidelines (27%) listed specific testing parameters, preferring isokinetic testing at 180° or 180° and 300° degrees per second. Similarly, 6 guidelines (55%) recommended using functional hop testing at this time. Five guidelines recommended evaluating quality of movement. Three (27%) guidelines mentioned use of agility tests, but no specific tests or criteria were outlined; instead, these guidelines favored general descriptions such as “symmetrical movement” or “good quality of movement” during agility activities. One guideline recommended an IKDC global rating of function >10 to RTS, whereas another recommended a Tegner score >90%.

Discussion

This study sought to examine current practices in postoperative PFI rehabilitation within specialty organizations familiar with managing these patients. Our findings suggest that significant variability in rehabilitation standards after MPFL reconstruction exists in PRiSM PF-RIG member institutions. Although outcomes after MPFL reconstruction are considered good, with dislocation events of 3% to 5%, a recent meta-analysis demonstrated that up to 11% of skeletally immature patients may have ongoing recurrent PFI or subluxation after surgery [24]. In addition, approximately 30% of patients do not RTS at prior levels, demonstrate prolonged lower extremity weakness, and express high levels of fear and lack of confidence in their knee stability after MPFL reconstruction [11]. Together, these data may indicate a need for improved postsurgical rehabilitation to enhance outcomes in this population. Although there appears to be consensus that objective strength or performance criteria should be employed to establish a better framework for clinical decision-making, most guidelines lack standardization and detail to guide clinical practice. This may create confusion in those evaluating postoperative recovery needs or performing outcome-based research.

This study has several limitations. We gathered guidelines only from member organizations of the PRiSM PF-RIG, which represents a homogenous sample of institutions specializing in pediatric sports medicine and engaged in research. Although our results may not apply to older populations, we focused on young athletes because they represent the highest risk demographic for first-time patella dislocations. In addition, the variation we found in rehabilitation practice may actually be greater among institutions that do not have academic or research objectives. This strengthens our conclusions for translational research efforts to improve standardization of assessment methodologies in rehabilitation. This study is further limited by the specificity and quality of each member organization’s guideline set. Often, functional goals were referenced but with vague descriptors that hampered synthesis and comparison.

Early functional goals after MPFL reconstruction include restoring normal gait mechanics and ensuring safe mobility while walking unsupported. The use of both time- and performance-based criteria facilitates optimal recovery by considering time associated with surgery- and patient-specific parameters such as strength, mobility, and muscle function. There was broad agreement in the guidelines that a period of limited weight-bearing is required, and all guidelines called for patients to be full weight-bearing by postoperative week 6. Although more than 90% of guidelines employed the use of postoperative bracing, the duration ranged from 6 to 12 weeks. Criteria to discontinue bracing were outlined in 64% of guidelines. A strength requirement was the most frequently cited criterion, but the mode of testing varied among a closed chain assessment using a single-leg squat, an open-chain straight-leg raise, or not specifying a particular assessment method and stating “adequate stability.” In order to safely discontinue the use of assistive devices for walking, a patient must demonstrate adequate knee motion and strength to stabilize the knee during single-limb stance. Although reliable and valid measures such as the lateral step-down test are available, our results indicate that rehabilitation guidelines are not employing available quantitative methods to structure the assessment of knee control [8].

Institutional guidelines rely largely on time-based criteria for mobility progression, with a 5-fold difference in the number of programs setting a time cutoff for activity compared with those setting functional goals such as isometric quadriceps benchmarks. Muscle function is critical to the stability of the patellofemoral joint and the protection of the MPFL graft from stress in early recovery. Thus, using time-based criteria in isolation to discontinue use of bracing or assistive devices, particularly in early rehabilitation, may be associated with increased risk of graft compromise [3].

The use of objective measures of strength combined with temporal metrics improved as patients neared the end of their recovery; of 11 guidelines, 8 cited strength cutoffs and 9 cited time cutoffs. Multiple studies have demonstrated that patients experience ongoing quadriceps weakness after MPFL reconstruction and that restoration of quadriceps strength is important to optimizing outcomes after knee surgery [1,12,20,22,25]. Despite this, only 27% of institutions recommended the use of isolated quadriceps assessment using an isokinetic dynamometer, the gold standard for muscle performance testing. Other institutions did recommend strength assessment, but they did not define a mode of testing. Although this recommendation may allow for flexibility, giving clinicians freedom to incorporate strength assessment tools they have available, it may also contribute to variability in clinical practice and inability to track recovery for large-scale outcomes research efforts. Variation in timeframes for sports participation was also noted, with a range of 16 to 36 weeks in the guidelines we reviewed. Although previous research noted similar levels of variability in RTS timeframes, the variation we found is more diverse. Lieber et al noted a range of time for RTS of 12 to 26 weeks within guidelines gathered from general academic orthopedic surgery programs [13]. The more widespread variation we found may reflect differences in sampling methodology, given that all institutions within this study specialize in pediatric orthopedics, which may influence recommendations based on patient physiology or developmental characteristics. Future research is warranted to explore physiologic progression of graft maturity, influence of quadriceps strength on functional outcomes, reinjury risk, and psychological readiness to RTS.

Single-leg hop tests are one of the most popular methods to assess limb function after knee surgery [16], but only 55% of guidelines recommended their use to analyze functional limb performance as a criterion to RTS. Of those that did make use of single-leg hop tests, there was significant variability in the mode or type of assessment, but the single-leg hop for distance and single-leg vertical hop were noted to have highest utilization. The lack of functional assessment and variation in testing mode is similar to that seen within other studies evaluating rehabilitation within MFPLR and ACL reconstruction rehabilitation [6,14]. Although there are limitations to single-leg hop tests and there is no agreed upon optimal test battery, efforts to improve the adoption of specific tests may help improve our understanding of recovery after MPFL reconstruction and assist in multicenter outcomes research efforts [5].

Valgus or rotational plane movement abnormalities in the lower extremities may increase laterally directed forces on the patellofemoral joint and play a role in PFI [2]. Therefore, incorporating tests to assess movement quality or dynamic knee control in closed chain activities seems important to minimizing reinjury risk in patients post-MPFL reconstruction. This recommendation is consistent with RTS assessment after ACL reconstruction, which shares similar risk factors and postoperative deficits as MPFL reconstruction [5]. Still, less than half of the guidelines evaluated recommended assessment of movement quality as a criterion to RTS. Of those that did, the majority did not identify a quantitative assessment method, rather deferring to individual, subjective standards of “good control” or “adequate knee stability.” Although objective measures of movement quality exist—such as the lateral step-down test, Landing Error Scoring System (LESS), or the Tuck Jump Assessment—they are not emphasized in current guidelines. This may reflect limitations in clinically relevant tools or a disconnect in translational research. Future research should focus on establishing the validity of movement assessments and implementation strategies for the post-MPFL reconstruction population.

In summary, we found significant variability in pediatric-focused postoperative rehabilitation guidelines after MPFL reconstruction, which tend to emphasize time-based recommendations for activity progression, with less focus on objective measures of muscle strength or functional performance. This may lead to suboptimal outcomes and limit efforts to compare across interventions or large-scale functional outcomes studies. Researchers should focus on establishing the validity of performance-based measures for identifying capacity to guide clinicians throughout the milestones of progression after MPFL reconstruction and effective dissemination efforts to facilitate incorporation of these measures into rehabilitation guidelines.