Patellar dislocation is a common orthopedic injury, with an overall incidence of acute first-time dislocation ranging between 2.3 and 23.2 per 100 000 person years, occurring often secondary to a non-contact flexion-rotation injury. The medial patellofemoral ligament (MPFL) is an hourglass shaped structure that originates on the superomedial aspect of the patella, and inserts onto the medial femoral epicondyle. This ligament is essential, as it serves as a primary checkrein to lateral patellar translation between 0-30 degrees of knee flexion. Surgical intervention often aims to replace this ligament to recreate this checkrein, in the form of MPFL reconstruction. Traditionally, patients who have sustained first-time patellar dislocations have been treated nonoperatively, and surgical intervention has mostly been reserved for patients with recurrent dislocations. However, the evidence behind this decision-making process is limited.
Specifically, a recently published a systematic review and meta-analysis comparing early MPFL reconstruction with rehabilitation, finding a pooled recurrent dislocation rate of 7% (95%CI 2-17%) in the reconstruction group compared to 30% (95%CI 25-36%) in the rehabilitation group. Another meta-analysis reported inferior rates of recurrent dislocation with rehabilitation (30%, 95%CI 25-36%) compared to acute MPFL repair (7%, 95%CI 3-12%). These findings were again found in the pediatric population, as reported by another meta-analysis published by our group, finding a pooled recurrent dislocation rate of 25.1% in the surgical group, compared with 46.4% in the conservative management group. When stratifying results by type of surgical procedure performed, the MPFL reconstruction group had a recurrent dislocation rate of 3.1% compared to that of other procedures, such as MPFL repair, lateral release, or medial imbrication, with a recurrent dislocation rate of 39.4%.
There have only been two prospective studies comparing MPFL reconstruction with rehabilitation for first-time dislocation. Based on the minimal number of adverse events, these studies demonstrated safety of early surgical intervention in first-time patellar dislocations, in addition to lower rates of recurrent patellar instability. However, allocation into treatment groups was not randomized in one study while the other study had a small sample size of only 39 patients which may bias and limit the applicability of the results.
This is a pilot randomized controlled trial (RCT) that will determine in patients under 25 years old with acute first-time patellar dislocations, the effect of early medial patellofemoral ligament (MPFL) reconstruction vs rehabilitation on recurrent dislocation rates, anterior knee pain, patient reported functional outcomes and complication rates at 12 months. The rationale for this trial is based on 1) the burden of patellar instability in the general population, 2) the high risk of progression to recurrent instability, 3) serious long-term, deleterious effects to the knee with recurrent instability, 4) the lack of definitive evidence or guidelines on the optimal treatment strategy in patients with these injuries, 5) promising results seen with early MPFL reconstruction in previous smaller studies, 6) lack of well-powered, high-quality, RCTs assessing early MPFL reconstruction after an acute first-time patellar dislocation patients. This trial is important and novel because it will provide surgeons with high-quality level I evidence to guide treatment decisions in patients with acute first-time patellar dislocations.
