[Anatomical double bundle reconstruction of medial patellofemoral ligament with allograft tendon in patellar dislocations].

OBJECTIVE: To investigate the clinical therapeutic results of allograft tendon for anatomical reconstruction of medial patellofemoral ligament (MPFL) in patellar dislocations.

METHODS: From September 2005 to June 2008, 20 patients with patellar dislocation underwent MPFL reconstructions. There were 4 males and 16 females, aged 13 to 31 years (19 years on average). Patellar dislocations occurred in 7 left and 13 right knees, including 6 cases of acute dislocation and 14 cases of recurrent dislocation. The disease course was 1 day to 2 years. The frequency of dislocation was 1-6 (4 on average). Affected knee joint showed pain, swelling and patellar instability; the range of action for patella obviously increased. The X-ray films showed patellar dislocation or medial margin avulsion fracture. The preoperative Q angle was (15 +/- 3) degrees, the congruence angle was (10 +/- 11) degrees. Reconstruction was performed via allograft tendon. Allograft tendon was anchored to the superomedial pole of the patella by two bone anchors, and the other end was fixed at the natural MPFL insertion site near the medial femoral condyle with an interference screw in a bone tunnel. All patients were evaluated postoperatively; Kujala patellofemoral scores, objective knee function, complications, and reoperations were assessed.

RESULTS: Primary healing was achieved in 18 cases and secondary healing in 2 cases. No infection or necrosis and absorption of grafts was observed. All patients were followed up for an average of 25.6 months (range, 6-34 months) postoperatively. At last follow-up, other patients had no pain, swelling and patellar instability except 1 case; neither patella redislocation nor fracture occurred. The X-ray films showed good position of anchors and tunnel 6 months after operation, and the congruence angle was (3 +/- 8) degrees, showed statistically significant difference when compared with preoperation (P < 0.05). The postoperative Q angle was (15 +/- 2) degrees, the Kujala knee function score improved significantly from 60.8 +/- 7.2 to 83.4 +/- 8.0 at last follow-up, showing statistically significant difference (P < 0.05). According to Insall et al. for function, the results were excellent in 12 cases, good in 6 cases, and fair in 2 cases, the excellent and good rate was 90%.

CONCLUSION: MPFL reconstruction improves clinical symptoms. Anatomical MPFL reconstruction is effective for patellar dislocation, and it offer good recovery of the pre-morbid patella mechanics. There would be little bone loss when tendon is fixed by anchors, and there would be less patellar fracture than bone tunnel technique. The bone anchors also provide firm fixation. Allograft can avoid the graft harvest site morbidity, but it increases the cost of the surgery.