This study showed that alpha angle, measured in one plane, was not a predictor of the radial extension of cam deformity. To achieve a full resection, it was frequently necessary to extend the femoral head osteoplasty over the retinacular area. Pre-operative determination of the omega angle and location of the vascular foramina helped improve cam resection safety and accuracy.

Purpose Using an extended retinacular flap containing the blood supply for the femoral head, proximal femur osteotomies can be performed at the neck level increasing the potential of correction of complex morphologies. The aim of this study was to analyze the safety, clinical, and radiographic results of this intra-articular surgical technique performed in skeletally mature patients with a minimum follow-up of three years. Methods Fourteen symptomatic adult patients (16 hips) with a mean age of 26 years underwent FNO using surgical hip dislocation and an extended soft tissue flap. Radiographs and radial magnetic resonance imaging (MRI) were obtained before and after surgery to evaluate articular congruency, cartilage damage, and morphologic parameters. Clinical functional evaluation was done using the Nonarthritic Hip Score (NAHS), the Hip Outcome Score (HOS), and the modified Harris Hip Score (mHHS). Results After surgery, no avascular necrosis was observed, and all the osteotomies healed without complication. The initial neck/ shaft angle (range 120 to 150°) improved in all cases to a mean value of 130°± 4.6 (p < 0.001). In eight of nine valgus hips, the high-positioned fovea capitis changed to a normal position after surgery. The NAHS score improved from a mean of 36.5 ± 14.9 to 82.9 ± 13.9 points after surgery (p < 0.001). After surgery, the mean HOS was 87.1 ± 17.6 points, and the mean mHHS was 78.6 ± 17 points. Conclusions In this series, femoral neck osteotomy in the adult, although technically more demanding compared with other classic osteotomies, can be considered a safe procedure with considerable potential to correct hip deformities.

FAI surgery can be considered effective in improving patient symptoms. There were no differences in clinical or radiographic results between techniques. We could more accurately predict the variation ratio of NAHS after surgery than its pre-operative value.