Introduction. Patients who are symptomatic with concurrent acetabular dysplasia and proximal femoral deformity may have Perthes disease. Osteotomies to correct both the acetabular and proximal femur deformities may optimise biomechanics and improve pain and function. In this study, we assessed the long-term results for such a combined procedure. Methods. We included patients who underwent concurrent pelvic and proximal femoral osteotomies by the senior surgeon (JNOH) with a minimum follow-up of 5 years. A modified triple pelvic interlocking osteotomy was performed to correct acetabular inclination and/or version with a concurrent proximal femoral osteotomy to correct valgus/varus and/or rotational alignment. We assessed functional scores, radiological paramenters, arthroplasty conversion rate, time interval before conversion to arthroplasty and other associated complications. Results. We identified 63 patients (64 hips) with a mean age of 29.2 years (range 14.3–51) at a mean follow-up of 10.1 years (range 5.1–18.5). The mean sourcil inclination postoperatively was 4.9. O. (range 1–12) compared to 24. O. (range 14.5–33) preoperatively. The mean Tonnis grade postoperatively was 2.2 (1–3) compared to 1.8 (range 1–2) preoperatively. At the last follow-up assessment, the mean Oxford Hip Score was 56 (range 60–47), Non-arthritic Hip Score was 71 (range 59–80) and UCLA activity score was 8 (range 5–10). There were 12 (18.8%) conversions to arthroplasty at a mean of 7.9 years (range 2.2–12.2) after surgery. Other associated complications include 1 sciatic nerve injury, 1 deep infection and 5 non-unions that required refixation. Discussion. Symptomatic acetabular dysplasia with concurrent proximal femoral deformity is difficult to treat. The use of combined pelvic and femoral osteotomies can optimise acetabular and femoral head alignment to improve pain and function with more than 4 out of 5 hips preserved at 10 years