Epiphysiodesis of the greater trochanter in Legg-Calvé-Perthes ...

310 A. VAN TONGEL, G. FABRYFig. 2. — The NSA (neck-shaft angle) on the AP radiograph(8).Fig. 1. — The ATD (articulo-trochanteric distance) is measuredas the distance in millimeters between two parallel linesperpendicular to the axis of the shaft of the femur, one at thelevel of the tip of the greater trochanter and the other at thehighest part of the ossified femoral head. The distance isrecorded as positive if the tip of the greater trochanter is caudalto the highest part of the femoral head and negative if thetip of the trochanter is proximal to the femoral head (8).The medical and radiological records from more thanone year before the operation were available in26 patients. Five patients were seen only one monthbefore operation. All 31 patients (32 hips) had postoperativeclinical and radiological follow-up. There were7 girls and 24 boys. The left hip was affected in23 patients, the right hip in 7 patients and in one patientboth hips were involved.The mean age at operation was 10 years and6 months, ranging from 7 years and 11 months to12 years and 1 month. The mean follow-up time was4 years and 2 months (range : 7 months to 7 years and9 months).Indications for epiphyseodesis were a positiveTrendelenburg sign with overgrowth of the greatertrochanter or an increase in relative overgrowth duringfollow-up.In 24 cases, a shelf acetabuloplasty was performed atthe same time. In 5 cases, only an epiphyseodesis of thegreater trochanter was done, and on two occasions theepiphyseodesis was done a few months after a shelfacetabuloplasty.The Phemister technique for epiphyseodesis asdescribed by Langenskiöld and Salenius (12) wasused (21).The growth of the greater trochanter was evaluated,using the articulo-trochanteric distance (ATD) (fig 1).The neck-shaft angle (NSA) was also measured (fig 2).Both measurements were done pre- and postoperatively,both on the affected hip and the normal hip (8, 17). Theclinical Trendelenburg sign was evaluated (2, 6) and comparedwith the ATD and the NSA of the involved hip.The results were analysed using statistical analysissoftware (SAS) (18). The age dependence of the ATD andNSA and the difference between boys en girls andbetween different procedures were analysed usingregression analysis. The differences between pre-andpostoperative observations were evaluated by analysis ofcovariance. The evaluation of the clinical situation wascalculated with the SIGN testRESULTSFirst the NSA and ATD of the normal hip wereevaluated. The average distance and angle for everypatient during one year (for example from the 7 th tothe 8 th birthday) were calculated. Regression analysisproduced curves, showing the evolution ofATD and NSA in the normal hips according to ageActa Orthopædica Belgica, Vol. 72 - 3 - 2006