Introduction. Torsional deformities are increasingly recognized as an additional factor in young patients with hip pain resulting from pincer- and cam-deformities. For example decreased femoral torsion can worsen an anterior Femoroacetabular impingement (FAI) conflict while an increased torsion can be beneficial with the same configuration. It is unknown how often torsional deformities are present in young patients presenting with hip pain that are eligible for joint preserving surgery. We questioned (1) what is the prevalence of a pathological femoral torsion in hips with FAI or hip dysplasia? (2) which hip disorders are associated with an abnormal torsion?. Methods. An IRB-approved retrospective study of 463 consecutive symptomatic FAI patients (538 hips) and a MRI or CT scan on which femoral torsion could be measured was performed (‘study group'). Out of 915 MRI we excluded 377 hips. The study group was divided into 11 groups: Dysplasia (< 22° LCE), retroversion, anteverted hips, overcoverage (LCE angle 36–39°), severe overcoverage (LCE>39°), cam (>50° alpha angle), mixed FAI, varus- (<125° CCD angle), valgus- (>139° CCD), Perthes-hips and hips with no obvious pathology. The ‘control group' of normal hips consisted of 35 patients (35 hips) without radiographic signs of osteoarthritis or hip pain wich was used for a previous study. Femoral antetorsion was measured according to Tönnis et al. as the angle between the axis of the femoral neck and the posterior axis of the femoral condyles. Normal femoral torsion was defined by Tönnis et al. as angles 10–25° while decreased resp. increased torsion was defined as <5° and >25°. Statistical analysis was performed using analysis of variances (ANOVA). Results. (1) Fifty-one percent of the patients of the study group presented with abnormal values for femoral torsion. Torsional deformities (<10° or >25°) were measured in 52% of all 538 hips eligible for joint preserving surgery. (2) Torsional deformities were present in 86% of Perthes hips, in 61 % of dysplastic hips, 52.3 % of hips with overcoverage, in 51% of mixed FAI, in 50% of varus hips, in 45% of valgus hips, in 45% of retroverted hips, in 47% of anteverted hips, in 43% of cam FAI, 35% of hips with severe overcoverage. No torsional deformity was present in the control group. Analysis of Variances (ANOVA) revealed significant differences (p<0.001) of torsion between normal hips (mean 17°) and hips with dysplasia (26°), valgus hips (27°), hips with no obvious pathology (30°) and Perthes hips (32°). Mean femoral torsion was in the normal range in the other groups. Conclusion. More than half of the patients wich are eligible for joint preserving surgery of the hip present with abnormal femoral torsion. In particular dysplastic-, valgus-, Perthes hips and hips with no obvious pathology had a significantly altered femoral torsion compared to normal hips. Femoral antetorsion should be measured in every patient eligible for hip-preserving surgery

Introduction. Torsional deformities of the femur have been recognized as a cause of femoroacetabular impingement (FAI) and hip pain. High femoral antetorsion can result in decreased external rotation and a posterior FAI, which is typically located extraarticular between the ischium and trochanter minor. Femoral osteotomies allow to correct torsional deformities to eliminate FAI. So far the mid-term clinical and radiographic results in patients undergoing femoral osteotomies for correction of torsional deformities have not been investigated. Objectives. Therefore, we asked if patients undergoing femoral osteotomies for torsional deformities of the femur have (1) decreased hip pain and improved function and (2) subsequent surgeries and complications?. Methods. We retrospectively evaluated 21 hips (18 patients) who underwent femoral osteotomies for correction of torsional deformities between April 2005 and October 2014. Twenty hips with excessive femoral antetorsion (47.7° ± 8.6°, range 32° – 65°) had a derotational femoral osteotomy. One hip with decreased femoral antetorsion of 11° underwent rotational femoral osteotomy. Previous surgery were performed in 43% of the hips including hip arthroscopy (5 hips), acetabular osteotomy (2 hips), open reduction for high dislocation (2 hips), surgical hip dislocation (2 hips) and varus intertrochanteric osteotomy (1 hip). In 10 hips a concomitant offset correction and in 5 hips a concomitant periacetabular osteotomy were performed. The mean followup was 3.6 ± 2.3 (1 – 10) years. One patient (one hip) died from a cause unrelated to surgery at the 2 year follow-up. We used the anterior and posterior impingement test to evaluate pain. Function was assessed using the Merle d'Aubigné Postel score, WOMAC, UCLA activity score and Harris hip score. Results. The incidence of a positive anterior impingement test decreased from preoperatively 85% to 29% at latest follow-up (p<0.001). The incidence of a positive posterior impingement test decreased from preoperatively 90% to 5% at latest follow-up (p<0.001). The mean Merle d'Aubigné Postel score increased from 13 ± 2 (11 – 16) to 16 ± 1 (13 – 17) at latest followup (p<0.0001). For the WOMAC, UCLA and Harris hip score no preoperative values existed but at latest followup they all showed fair to good values with a mean WOMAC score of 14 ± 15 (1 – 50), UCLA score of 6 ± 1 (3 – 8) and Harris hip score of 77 ± 13 (47 – 96). Subsequent surgeries included hardware removal in 14 hips (66%) and hip arthroscopy with offset creation in 1 hip. Complications occurred in 5 hips (24%) all graded Grade III according to Sink and included conversion to total hip arthroplasty in 1 hip, reosteosynthesis due to pseudarthrosis in 3 hips and hip arthroscopy for adhesiolysis in 3 hips. Conclusion. Femoral osteotomies for the treatment of torsional deformities of the femur result in decreased pain and improved function in patients with FAI. However, these procedures are associated with a complication rate of 24% which is mainly due to pseudarthrosis and intraarticular adhesions in patients with concomitant offset correction