Does Previous Hip Surgery Effect the Outcome of Tonnis Triple Periacetabular Osteotomy? Mid-Term Results

Hip dysplasia (HD) is 1 of the major reasons of coxarthrosis. The goal of the treatment of HD by Tonnis triple pelvic osteotomy (TPAO) is to improve the function of hip joint while relieving pain, delaying and possibly preventing end-stage arthritis. The aim of this study is to compare the clinical and radiological results of TPAO to determine if previous surgery has a negative effect on TPAO. Patients operated with TPAO between 2005 and 2010, included in this study. Patients divided into 2 groups: primary acetabular dysplasia (PAD) and residual acetabular dysplasia (RAD). Prepostoperatively, hip range of motion, Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) hip score, visual analog scores (VAS), impingement tests, and also the presence of Trendelenburg sign (TS) were investigated for clinical evaluation. For radiological analysis pre-postoperative, anterior-posterior (AP) pelvis and faux profile radiographs were used. Acetabular index, lateral center edge (LCE) angle, and Sharp angles were measured by AP pelvis; anterior center edge (ACE) angle were measured by faux profile radiography. All the clinical and radiological data of the groups were analyzed separately for the pre-postoperative scores also the amount of improvement in all parameters were analyzed. SPSS20 (SPSS Inc., Chicago, IL) was used for statistical analysis. Wilcoxon test, McNemar test, paired t tests, and Mann-Whitney U tests were used to compare the groups. P<0.05 were defined as statistically significant. Study included 27 patients: 17 patients were in PAD and 10 patients were in RAD. The mean follow-up period was 6.2 years (5.2-10.3 years). In all patients, the radiological and the clinical outcomes were better after TPAO except the flexion of the hip parameter. When the patient groups were evaluated as pre-postoperatively, more statistically significant parameters were found in the PAD group when compared with RAD group. Extension, impingement, TS, VAS, HHS, WOMAC score parameters in clinical outcome and LCE, ACE, Sharp angle, coverage ratio in radiological results were significantly better in PAD group postoperatively but in RAD group; only extension, VAS, HHS, and WOMAC parameters were clinically and LCE and Coverage ratio were significantly different compared with the preoperative measurements. The change of the parameters that used for the evaluation of clinical and radiological results did not show a significant difference between groups. Our data suggest that TPAO can be performed on patients with HD for both groups. Although there were fewer parameters which changed significantly after TPAO in RAD patients; the improvement of radiological and clinical results was similar for groups. Further long-term follow-up studies with large number of patients are needed to determine the proper results of TPAO.