Biologic Augment of the Medial Patellofemoral Ligament Following Primary Lateral Patellofemoral Dislocation (BioPPD)

This study aims to determine the ability of medial patellofemoral ligament (MPFL) repair augmented with Biobrace® to decrease the re-dislocation rate after a primary patellofemoral dislocation. First-time patellofemoral dislocation is a significant problem, and the ramifications of recurrence for patients are substantial. Due to the multifactorial nature of the pathoanatomy of patellofemoral instability, it has been difficult to design trials that will show how interventions could affect the natural history of these young patients. No definitive studies have determined whether the surgical reconstruction of the MPFL in patients with mild to moderate pathoanatomic risk factors will decrease the re-dislocation rate after a first-time dislocation. In addition, to date, no synthetic option has provided both biology and strength for ligament augmentation. This innovation may allow for a minimalist approach to keeping the patella centred in the trochlear groove during the healing phase after a first-time dislocation.

This study aims to determine the ability of MPFL repair augmented with Biobrace® to decrease the re-dislocation rate after a primary patellofemoral dislocation. The null hypothesis is that there will be no difference in re-dislocation rate 2 years after surgical stabilization with Biobrace® compared to the natural history of patellar instability.

Patellofemoral instability is a well-recognized and common knee joint injury. Studies reporting the natural history after a first-time patellofemoral dislocation have reported a recurrence rate ranging from 10-80%. Recurrence varies depending on the unique pathoanatomic risk factors of each patient. Risk factors related to recurrence after a first-time dislocation include open growth plates, age at first dislocation, trochlear dysplasia, increased tibial tubercle - trochlear groove (TT-TG) distance, contralateral dislocation, and patella alta. A recent systematic review and meta-analysis determined the redislocation rate in patients managed without surgery after a first-time dislocation was 30%.

The MPFL plays a critical role in the constraint of lateral translation of the patella, providing 50-60% of the soft tissue restraint in early flexion before the patella engages in the trochlear groove. Essentially, the MPFL guides and holds the patella in the trochlear groove, especially between 0-45 degrees of flexion. MPFL insufficiency is present in as many as 90% of acute patellar dislocations and up to 100% of recurrent cases. The traditional non-operative treatment for a first-time dislocation has been to splint the knee in extension, which may prevent further dislocation but does not reduce the patella in the trochlear groove so that the medial soft tissue can heal in an anatomic position.

Multiple studies have investigated operative and non-operative treatments that aim to reduce recurrence after a first-time patellofemoral dislocation. To date, the type of knee immobilization has not been demonstrated to influence the recurrence rate. Operative management has been investigated compared to traditional non-operative treatment. A systematic review tabulated 15 studies comparing MPFL repair to non-operative management demonstrated decreased re-dislocation rates and decreased knee pain in those with surgical repair. Liebensteiner et al. reviewed studies with level 1 or 2 evidence and concluded that there are mixed results and that consensus on the ideal management after a first-time dislocation is still unclear. Despite these published results, surgical treatment after a first-time dislocation has not found widespread acceptance.

Further trials have compared MPFL repair to MPFL reconstruction. Bitar et al. conducted a study of MPFL reconstruction compared to non-operative management using the current a la carte indications for isolated MPFL reconstruction. These authors concluded that MPFL reconstruction was superior for preventing re-dislocation of the patella. Another recent retrospective review of 76 patients with an osteochondral lesion followed for 2 years compared MPFL-R to MPFL repair or no treatment. This study determined that completing an MPFL-R at index surgery resulted in a 5-fold reduction in recurrent instability.

Synthetic products can be used as a graft to reconstruct an MPFL. A systematic review has reported good results at a minimum of 2 years post-operative. Most synthetic products available today to augment or enhance the repair of ligaments are designed to address only one of two failure mechanisms: they either add mechanical strength without biological healing or aid in remodelling the underlying tendon tissue without providing mechanical strength during surgical repair. The inability of current devices to both strengthen the repair and create a favourable healing environment for cellular infiltration and tissue growth has led to further innovation and the development of the Biobrace® implant by Biorez. The Biobrace® implant is intended for use in general surgical procedures to reinforce soft tissue where weakness exists. The Biobrace® implant is also designed to reinforce soft tissues repaired by suture or suture anchors during tendon or ligament repair surgery.

Eligibility Criteria:
Inclusion Criteria:

* Age 13 - 30 years
* First-time lateral patellofemoral dislocation in the previous 7 days
* Closed or closing growth plates (confirmed on knee x-rays with no change required for surgical technique)

Exclusion Criteria:

* History of previous patellofemoral dislocation on the index knee
* An osteochondral fracture of the patellofemoral joint that requires surgical repair
* Unable to complete computer-based outcome questionnaires
* Pregnant at the time of surgery