This study involves patients between the ages of 16 and 25 and have been diagnosed with a first-time traumatic patellar dislocation within the past 3 months. McMaster University and the investigators are receiving compensation from the Arthroscopy Association of North America to cover the costs of conducting the study.

Dislocations of the kneecap or patella is often treated without surgery, however up to 50% of patients will unfortunately experience recurrent instability of the patella. These episodes can cause damage to the bones and cartilage in the knee, which can result in long-term knee pain or weakness. Therefore, there is increasing interest to consider treating the knee with surgery right away in this population.

The purpose of this study is to determine the effect of medial patellofemoral ligament (MPFL) reconstruction compared to rest and physical rehabilitation on the rate of repeat patella dislocation, pain, and knee function for patients with their first patellar dislocation. The investigators will follow patients for at least one year after assigned treatment is started. Outcomes will be measured using surveys and checking medical records over the course of the study. The pilot will test this research study on a smaller scale before conducting a larger study. Patients will not be asked to attend additional visits outside of their typical follow-up schedule with their doctor.

There will be 30 patients recruited in total for this pilot study. Not all patients diagnosed with a patellar dislocation will be eligible to participate. Participation will be required at 6 regularly scheduled appointments that patients would need to attend to see the surgeon (even if they were not in the trial), including the screening visit, surgery date (if randomized to that treatment), 2-week, 6-week, 3-month, 6-month, and 12-month follow-up visits. Patients will be asked how they feel via various questionnaires and should take no longer than 15-20 minutes to complete the research forms at each visit.

If patients agree to participate in this study, treatment will be determined by a process called randomization. Randomization means that the treatment the patient receives will be decided by chance like flipping a coin. Patients will have a 1-in-2 chance of receiving one of the following treatments:

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.

Inclusion Criteria:

1. Males and female patients under the age of 25 inclusive but greater than 10 years of age inclusive
2. Patients with first-time traumatic lateral patellar dislocation presenting within 6 months from time of injury
3. Lateral patellar dislocation confirmed by radiography, MRI demonstrating sequela of lateral patellar dislocation after injury to the knee, demonstration of patellar apprehension, J-sign or patellar glide grade 3 or greater on physical exam following injury to the knee
4. Patients who have the ability to speak, understand, and read English
5. Provision of informed consent or parental consent

Exclusion Criteria:

1. Previous dislocation episodes or instability of the affected patella
2. Previous surgeries involving the affected knee
3. History or clinical exam findings of generalized ligamentous laxity (defined as Beighton score of 4 or more points)
4. TT-TG distance >20mm as determined by MRI
5. Evidence of severe trochlear dysplasia on MRI as determined by Dejour classification type D dysplasia
6. Loose bodies or osteochondral fractures as confirmed on MRI
7. A neurovascular injury of the affected leg
8. Patients who will likely have problems, in the judgment of the investigator, with maintaining follow-up
9. Any other reason(s) the investigator feels is relevant for excluding the patient
10. Patients requiring concomitant arthrotomy for osteochondral fracture fixation (however microfracture and arthroscopic loose body removal for loose bodies found on arthroscopic assessment are not exclusion criteria)

IPD will not be shared to avoid risks of compromising patient confidentiality.