Summary

Sulcus-deepening trochleoplasty can provide a reliable and successful surgical solution to recurrent patellar instability.

Abstract

Objectives:
Patellar instability caused by severe trochlear dysplasia may be addressed by sulcus-deepening trochleoplasty. There is a paucity of data from the United States regarding this procedure and no long term follow up. The purpose of this study was to evaluate the outcome data of patients undergoing sulcus-deepening trochleoplasty for high-grade trochlear dysplasia at our institution.

Methods

A total of 75 patients (82 knees) with severe trochlear dysplasia were prospectively enrolled and underwent sulcus-deepening trochleoplasty using the Dejour method from 2011-2018. The trochlea was osteotomized to create a thick shell (shingles) that were molded to form a new trochlear shape then fixed with absorbable suture anchors. Forty-two of 82 knees (51.4%) had prior surgery and failed prior surgical management for patellar instability. Concomitant procedures during trochleoplasty included medial patellofemoral ligament reconstruction (MPFL) (100%), lateral release or lengthening (51.5%), tibial tubercle osteotomy (33.8 %), and some type of cartilage procedure (42.6%) to include shaving chondroplasty (39.7%), chondral allograft (10.3%), microfracture (7.4%), and removal of loose body (23.5%). Radiographic analysis, physical examination, and clinical follow-up were obtained for all patients. At the time of enrollment, patients completed preoperative visual analog scores (VAS), international knee documentation committee (IKDC) and Kujala scores, which were repeated at their 6 month, 1 year, 2 year, 3 year, and 4 year follow-up visits. Patients reported on their return to work and sport, if applicable, as well as any instances of recurrent instability. Preoperatively, the patellotrochlear index (PTI), trochlear spur height, and trochlear depth were all measured. The patient’s sulcus angle was measured preoperatively and post operatively on sunrise (merchant) view xray. Of the entire cohort, 45 patients (52 knees) had at least one year complete follow-up including xrays, physical exam, and patient reported outcome measures and were included in the study.

Results

The majority of patients were female (76.9%) with a mean age of 19.7 +/- 6.7 years. Follow-up ranged from 12 months to 78.4 months (mean 28.7 +/- 15.7). At the time of enrollment, mean BMI was 27.2 kg/m2 (+/- 6.3) with one current smoker and one diabetic patient. Mean duration of symptoms prior to surgery was 75.7 months (+/- 71.5; r: 4-370 months). All knees were either Dejour B (78.4%) or D (21.6%) with a mean Caton-Deschamps index (CDI) of 1.19 (+/- 0.2). Mean spur height preoperatively was 7.44mm (+/- 1.83mm) with a mean trochlear depth -0.14 (+/- 2.67). Mean patellotrochlear index (PTI) was 0.41 (+/- 0.40). There were zero episodes of recurrent instability. One patient had patellar apprehension and a recurrent J-sign at terminal extension postoperatively requiring a distal femoral osteotomy for genu valgum. All patients reported clinically significant improvements compared with baseline preoperative outcome scores. The mean preoperative IKDC score was 50.15, which improved to 79.08 (p <0.001), and the mean preoperative Kujala score was 55.92, which improved to 85.58 (p <0.001). Patients reported high satisfaction rates (mean 9.4 +/- 1.5 out of 10). All but 1 patient (96.9%) returned to work while 88.2% of patients were able to return to sport. Ten knees (20.4%) developed arthrofibrosis and required manipulation under anesthesia while eight of which underwent simultaneous arthroscopic lysis of adhesions. At the latest follow-up, mean knee range of motion was 132.4 +/- 13.2 degrees. No patients had fixation failure or progression of arthritis. Preoperative VAS was 2.41 (right) and 3.37 (left) while postoperative was 1.26 (right) and 1.68 (left) (p= 0.003 right, 0.001 left). Radiographic analysis of the sulcus angle demonstrated a significant decrease from 148.55 degrees (+/- 11.42) preoperatively to 135.48 degrees (+/- 8.85) postoperatively (p < 0.001).

Conclusion

When indicated in the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty can provide a reliable and successful surgical solution to recurrent patellar instability. At a minimum of one year follow-up, the majority of patients were satisfied with their outcome corroborated by their subjective, validated outcome measures.