Incidence and radiologic predictor of postoperative patellar instability after Fulkerson procedure of the tibial tuberosity for recurrent patellar dislocation.
OBJECTIVE
Excellent results of anteromedialization of the tibial tuberosity for recurrent patellar dislocation have been reported; however, the contribution of the preoperative anatomic factors to postoperative patellar instability has not been well established. The purpose of this study was to investigate the mid-term results and the incidence of postoperative patellar instability after Fulkerson procedure for recurrent patella dislocation, and to determine the radiologic predictor of the postoperative patellar instability.


METHODS
Sixty-two knees of 41 patients underwent Fulkerson procedure with or without lateral retinacular release for recurrent patellar dislocation and were followed-up for 85-155 months. Predisposing anatomic factors for recurrent patellar dislocation were evaluated preoperatively, including valgus knee alignment (femorotibial angle), patella alta (Insall-Salvati ratio), trochlear dysplasia (trochlear depth), lateral patellar displacement (congruence angle) and lateral malposition of the tibial tuberosity (tibial tuberosity-trochlear groove distance). The relationship between the measurements of anatomic factors and postoperative patellar instability, which was defined by the patellar re-dislocation or residual apprehension after surgery, was analyzed.


RESULTS
The Fulkerson score and the Kujala score were significantly improved from the median of 65 (35-80) points and 68 (36-82) points preoperatively to 95 (60-100) points and 92 (57-100) points at the final follow-up, respectively. Three knees (4.8%) experienced postoperative patellar re-dislocation and 4 knees (6.5%) showed the positive apprehension sign at the final follow-up. The statistical analysis showed that the postoperative patellar instability correlated with only patella alta.


CONCLUSIONS
Patella alta was the only predictor of postoperative patellar instability after Fulkerson procedure. These results indicated that isolated Fulkerson procedure should not be indicated for recurrent patellar dislocation with severe patella alta.


METHODS
Case-control study, Level III.
Department of Orthopaedic Surgery, Hirosaki University Graduate School of Medicine, Zaifu-cho 5, Hirosaki, Aomori, 036-8562, Japan. eiichi@cc.hirosaki-u.ac.jp
Eiichi
E
Tsuda
Yasuyuki
Y
Ishibashi
Yuji
Y
Yamamoto
Shugo
S
Maeda
D000293:Adolescent; D000328:Adult; D017760:Bone Malalignment / Q000150:complications / Q000000981:diagnostic imaging; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D016015:Logistic Models; D008297:Male; D019637:Orthopedic Procedures / Q000379:methods / Q000534:rehabilitation; D031222:Patellar Dislocation / Q000000981:diagnostic imaging / Q000209:etiology / Q000534:rehabilitation / Q000601:surgery*; D057071:Patellofemoral Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D011300:Preoperative Care; D011446:Prospective Studies; D012008:Recurrence; D012307:Risk Factors; D013977:Tibia / Q000601:surgery*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult