SOFT TISSUE RELEASE AND CONTINUOUS ILIOFEMORAL DISTRACTION FOR TOTAL HIP ARTHROPLASTY IN HIGH DEVELOPMENTAL HIP DISLOCATION OVER 40 MM

Abstract

Introduction: High developmental hip dislocation is the most severe anatomic constitution type in developmental dysplasia of the hip (DDH). After the age of 30–40 years the pseudo-articulation often becomes painful and requires advanced treatments. To restore limb length dislocation must be reduced by soft tissue release. If the reduction overreaches 40 mm the risk for nerve-damage increases dramatically. Reducing the dislocation, one-step soft tissue releases and slow release by continuous iliofemoral distraction were invented. In this study we report a combination of a one-step soft tissue release and slow continuous iliofemoral distraction in patients requiring over 40 mm distraction for uncemented THA.

Material and Methods: Between 1998 and 2007 20 procedures in 19 patients with an age of 42.5 years (18–69 years) and a leg-length discrepancy of > 4 cm were performed. For 5.6 years (1–12 years) patients were followed-up clinically and radiographically. The treatment consisted of a two-step procedure. 1st operation: Soft tissue releases combined with the implantation of the THA components and placement of the external distraction apparatus. In the interval period slow iliofemoral distraction of 1mm–1.5 mm per day was conducted. Neurovascular signs and distraction was regularly monitored until the desired length was achieved. 2nd operation: the external fixation device was removed before applying the acetabular PE-inlay and the femoral head. Subsequent reduction was easy in most cases.

Results: A distraction of 51 mm (41 mm–75 mm) in 61 days (32–94 days) with an indicated speed of 1–1.5 mm/d and an effective speed of 0.8 mm (0.4 mm/d–1.8 mm/d) was achieved. Treatment time was 86 days (50–210 days). Patients had to maintain 132 days (40–300 days) restricted weight bearing. 2.6 (2–6) interventions were performed until final reduction. Harris Hip Score increased by 43 points [44 (22–65) to 83 points (66–98)]. The patients showed satisfying increases in all dimensions of the SF-36 health score. In the course of treatment pin-instability was seen in 6 cases, 3 minor intraoperative femoral fractures, 3 infections and 3 nerve damages occurred.

Discussion: The experiences of this study state the difficulties in the treatment of high DDH. The complication rate was high, but patients seemed to be satisfied finally. However, final scores were lower than in patients undergoing hip arthroplasties for degenerative osteoarthritis. Results of this treatment can be improved by avoiding certain pitfalls like insufficient soft tissue release, trans-cortical placement of the iliac screws or fast distraction. Nevertheless, soft tissue release and continuous iliofemoral distraction is the only option to restore limb-length and to preserve neurologic structures in cases with a dislocation over 40 mm.