Comparison of Dynamic and Static Medial Patellofemoral Ligament Operation Technique for Recurrent Patellar Dislocation

DynMPFL - Comparison of Dynamic and Static Medial Patellofemoral Ligament Operation Technique for Recurrent Patellar Dislocation

This study is to evaluate whether the dynamic Medial Patellofemoral Ligament (MPFL) reconstruction as described by Becher is a successful operation technique to prevent patella instability and restore quality of life. It is to assess and compare clinical and functional outcomes of dynamic and static medial patellofemoral ligament reconstruction

The recurrent dislocation rate of conservatively treated chronic patellar instability is high, therefore, it is recommended to manage it surgically. A frequently used surgical technique is static medial patellofemoral ligament (MPFL) reconstruction (e.g. Schöttle-technique). A novel dynamic surgical technique according to Becher was developed, addressing the most common complications occurring in static reconstruction, which are malpositioning and overtensioning of the graft. This study is to assess and compare clinical and functional outcomes of dynamic and static medial patellofemoral ligament reconstruction.

Inclusion Criteria:

• Patients treated with isolated dynamic (operation procedure according to Becher et al.using the gracilis tendon) or static MPFL plastic (operation procedure according to Schöttle et al. using the gracilis tendon). MPFL reconstruction will be performed in patients with preceding patella dislocation with: 1) a Patella-Instability-Severity (PIS) score ≤ 3 with concomitant flake fracture or 2) a PIS score ≥ 4 with clinical asymptomatic trochlea dysplasia (patella stability between 30°-60° knee flexion) without other clinically relevant static risk factors.
• Closed growth plates

Exclusion Criteria:

• Combined procedures with trochleoplasty (high grade trochlea dysplasia, type Dejour C,D with clinical instability between 30° and 60° of knee flexion)
• combined procedures with cartilage transplantation
• High grade patellofemoral arthritis (Kellgren Lawrence score ≥3)
• combined procedures with femoral or tibial osteotomy
• Clinically eminent valgus axis (>15° valgus)
• Femoral internal rotation >20°, tibial external rotation >40°
• Instability of the cruciate or collateral ligaments
• Known significant musculoskeletal disease
• Cognitive impairment