Background

Patellar dislocation disrupts the proximal-medial patellofemoral complex (MPFC), which is composed by the medial patellofemoral ligament (MPFL) and the medial quadriceps-tendon femoral ligament (MQTFL). Isolated MPFL reconstruction provides good outcomes, but with variable rates of recurrent instability. Our aim was to compare the surgical outcomes and new dislocation episodes between isolated MPFL reconstruction and combined reconstruction of the MPFL and MQTFL.

Methods

Prospective cohort study that included all consecutive patients with objective patellar instability, defined as at least one previous patellar dislocation. Patients were divided according two groups: group 1, isolated MPFL reconstruction; group 2, combined reconstruction of the MPFL and MQTFL. The isolated MPFL reconstruction was performed using a semitendinosus autograft and the combined reconstruction of the MPFL and MQTFL using semitendinosus and gracilis autografts. In both groups, the grafts are fixed at the femur by looping around the adductor tendon insertion (quasi-anatomical point). In group 1, the graft is fixed at the adjacent retinaculum of the medial border of the patella with sutures. In group 2, while the two arms of the gracilis graft are sutured to their own substance and to the quadriceps tendon, the two arms of the semitendinosus graft are sutured at adjacent retinaculum of the medial border of the patella. Pain (visual analogue scale) and functional (Kujala score) outcomes were evaluated at baseline and upon 2-year follow-up. The rate and time to return to sports and the number of new dislocation episodes were also evaluated at 2-year follow-up.

Results

A total of 14 patients (19.5 ± 6.0 years, 22.1 ± 3.5 kg/m2, 43% males) and 18 knees (9 right and 9 left knees) were included. Group 1 had 12 patients and group 2 had 6 patients. The median number of previous dislocations was 3 (25% and 75% quartiles, 1 and 3) and the duration of symptoms ranged from 1 week to 15 years. Four patients reported previous surgical interventions (any knee), with an overall rate of 0.33 ± 0.69 of previous surgeries per patient. Age, body mass index, sex, number of previous dislocations, and Kujala and pain at baseline were homogenous between groups (p>0.05). The Kujala and pain were comparable between groups 1 and 2 at 2-year follow-up (91.9 vs 92.7 for Kujala, and 1.3 and 1.0 for pain; p>0.05). Improvement in Kujala and pain scores was also similar between groups (p>0.05). None of the patients, regardless of the group, had a new dislocation episode. From the 12 patients that are athletes, although not statistically different (p>0.05), the rate of return to sports was higher in group 1 (100% vs 75%), but group 2 returned faster to sports (14.6 vs 5.7 months).

Conclusion

Isolated MPFL reconstruction and combined reconstruction of the MPFL and MQTFL show comparable clinical and functional outcomes. While isolated MPFL reconstruction resulted in a higher rate of return to sports, those with combined reconstruction of the MPFL and MQTFL returned faster. These results should however be considered with caution as these are still preliminary and with a low sample size.