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
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
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
Parallel
Static reconstruction technique according to Schöttle
Procedure/SurgeryIn static MPFL reconstruction, a graft (harvested autologous gracilis tendon or allogen transplant) is attached to the femoral and patellar bones using tunnels, screws, and/or anchors.
Dynamic reconstruction technique according to Becher
Procedure/SurgeryDynamic MPFL procedure by detaching and reinserting only the distal part of a hamstring muscle to the patella and leaving the proximal tendon attached to its muscle. This way the patella position can be adjusted dynamically by hamstring contraction.
Change in Kujala score
Patient reported knee function and anterior knee pain as assessed with the Kujala score at preoperative screening, at the hospitalization time and four postoperative follow ups . The Kujala scale consists of 13 questions covering a range of physical symptoms and limitations that are presented in a multiple choice answer format, with a different point value assigned to each answer. The maximum score is 100, with higher scores indicating better function.
Number of recurrent patella dislocation
Surgical outcome: recurrent patella dislocation.
Number of revision surgery
Surgical outcome: revision surgery.
Number of complications (other than revision surgery, e.g. infection, wound healing disorder)
Surgical outcome: complications (other than revision surgery, e.g. infection, wound healing disorder).
Change in Banff-II-score from preoperative screening, at the hospitalization time and four postoperative follow ups
The Banff Patella Instability Instrument (BPII) is a disease-specific health-related quality of life score. It is a patient-reported, disease-specific QOL score that consists of 23 questions across five domains covering symptoms/physical complains, work-related concerns, recreational activity and sport participation/competition, lifestyle, and social/emotional. Patients mark their answers on a visual analogue scale measuring 100 mm in length. Each item is equally weighted with the final score calculated as an average of the scores from all answered items. A higher score reflects a higher QOL.
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