Synthetic versus autologous reconstruction (Syn-VAR) of the medial patellofemoral ligament: a study protocol for a randomised controlled trial

Recurrent patellar instability incidence is 5.8/100,000 population, and recurrent dislocations are reported in the range of 15–80%. Recurrent instability is multifactorial and can be associated with disorder of limb alignment, osseous development, congruity of the patella in the trochlea and soft tissue static and dynamic constraints. The multifactorial aetiology makes management challenging, and a lack studies in a heterogeneous population with robust clinical outcomes compounds this further. The options for medial patellofemoral ligament (MPFL) reconstruction include autologous graft reconstruction with semitendinosus tendon, or synthetic polyester woven grafts. In theory, in the young active patient, the surgeon may wish to preserve the hamstring tendons to reduce postoperative morbidity to the patient, reduce delay in recovery from donor site morbidity and preserve the hamstring tendons. There have been no randomised controlled trials (RCTs) to date that directly compare autologous hamstring and synthetic reconstruction methods. This trial aims to assess the functional outcomes in those undergoing MPFL reconstruction with either autologous hamstring graft reconstruction, or a commercially available synthetic polyester open woven tape.

Following a power calculation using previous studies as the pilot data, a total of 30 patients will be included in the study. Enrolment is based upon strict inclusion/exclusion criteria outlined in the “Methods”. Participants will be randomized to receive either autograft or synthetic graft reconstruction. We aim to recruit 15 patients to each arm of the study. Surgery is performed by a single consultant surgeon experienced in both reconstructive options, using the default surgical technique for each. A postoperative physiotherapist-directed rehabilitation protocol will be implemented, as is routine. The primary outcome is the Kujala functional score and its change over the study period. Data on further secondary outcomes using validated outcomes scores will also be collected, specifically the Tegner and Lysholm, Banff Patellar Instability Index, and ACL Quality of Life Score. Secondary outcomes are complications and revision for any reason. The patient follow-up time is 2 years. The first patient will be recruited in January 2018. The expected trial deadline for recruitment is December 2018, with records and results being held for 5 years.

This RCT study is the first to directly compare the efficacy of autograft versus synthetic allograft in MPFL reconstruction and the graft effects on patient-reported clinical outcomes.

ISRCTN, 16657952. Registered on 3 March 2017.

The study protocol has been approved by the Office for Research Ethics Committees of Northern Ireland (ORECNI 17/NI/0129).