Results of medial retinacular imbrication in patients with unilateral patellar dislocation

Many surgical methods are used for treating malaligned patella after patellar dislocation, but one surgical method may not be appropriate for all patients. The purpose of this study was to determine the radiographic and subjective outcomes of patients who underwent imbrication of redundant medial structures. A total of 42 patients met the inclusion criteria of suffering a traumatic, unilateral patellar dislocation and had no J-sign, no patella alta, asymmetry on Merchant view radiograph with normal patella alignment on the noninvolved side, and MRI showing injury to the medial retinaculum. Patients were prospectively evaluated. A total of 38 patients (mean age 19.2 years) completed follow-up evaluations at a mean of 31.7 months postoperatively. Mean congruence angle improved from 19.7° preoperatively to 5.4° postoperatively (p < 0.001) and was not statistically significantly different than the noninvolved knee of 4.1 (p = 0.5194). The mean linear displacement measurement improved from 6.0 mm preoperatively to 1.6 mm postoperatively (p < 0.001) and was not statistically significantly different than the noninvolved knee of 1.4 mm (p = 0.6294). Total 33 of 38 patients (87%) returned to their preinjury activity level including sports. Three patients had recurrence of patellar dislocation after surgery while playing sports. For patients who have the specific indications for imbrication of the medial retinaculum, surgery can be successful for re-establishing normal patellofemoral alignment and restoring function.