Total hip arthroplasty for arthrodesed hips

Journal of Orthopaedic Surgery, Jun 2002 by Howard, M B, Bruce, W J M, Walsh, W, Goldberg, J A

ABSTRACT

The benefits of converting an ankylosed or arthrodesed hip to total hip arthroplasty have been reported in the literature as have the technical difficulties associated with this procedure.1,2,4 This review, however, outlines the experience of a single surgeon (WJMB) at a single institution using uncemented prostheses.

Between November 1991 and June 1996, 5 arthrodesed hips underwent uncemented total hip arthroplasty in 4 males and 1 female. Clinical and radiological follow-up review was for at least three years in all patients.

In general, patients were satisfied with the outcome of their surgery with Harris Hip scores improving from an average of 62 preoperatively to an average of 72 postoperatively. The surgical outcome in these difficult cases was not as satisfactory as for routine total hip arthroplasty.

Meticulous preoperative planning is required to aim toward leg length restoration and restoration of the abductor moment arm5. A modular prosthesis allows versatility at surgery.

Key words: arthrodesis, total hip arthroplasty, uncemented arthroplasty

INTRODUCTION

The conversion of an arthrodesed hip of long standing to a total hip arthroplasty can be a difficult undertaking. It is a relatively uncommon procedure. In just over 4 years, 5 such operations have been performed at our institution, utilizing uncemented components.

Previous published series 5,8,11 outlined the fact that the effect of previous operation and altered anatomy, in addition to atrophy of abductor musculature, made the undertaking of conversion arthroplasty difficult. In addition, the ultimate results of arthroplasty are inferior to published series of patients with degenerative arthritis.

However, these series also pointed out the potential benefits to patients undergoing conversion arthroplasty. These include increased maneuverability and ability to sit comfortably.

METHODS

From November 1991 to June 1996 at Concord Repatriation General Hospital, 5 arthrodesed hips were converted to total hip replacement. There were 4 males and 1 female patient with an average age of 46 years (range 24 to 59 years). Surgical arthrodesis had been performed in 3 patients (1 for tuberculous infection, and 2 for post traumatic arthritis) whilst ankylosis had occurred in 2 patients (1 following fracture dislocation of the hip and 1 following chondrolysis). Average length of arthrodesis was 25 years (range 8-50 years) (Table 1).

The predominant indication for surgery in our patients was back pain and ipsilateral knee pain. In each patient these have been progressive phenomenon. No arthrodesis was painful preoperativey. In addition, most of our patients reported limited walking distance and difficulty in performing activities of daily living such as climbing stairs and tying shoe laces. All of our patients had hips fused in unsatisfactory positions (Table 1) and patients had measured limb length discrepancies (average 3 cm), with the maximal deformity noted in the patient with previous tuberculous infection of 10 cm.

Preoperatively, X-ray templating was undertaken to carefully plan anatomical reconstruction and to assess the use of the most appropriate approach depending on patient anatomy and previous surgery.

Biomechanical restoration was planned by attempting to reconstruct prosthetic offset to match the abductor moment arm with the moment arm at the centre of gravity of the pelvis.- This was difficult in early cases as the options for offset were poor in the early prosthetic designs that we employed (Fig. lb). In addition, acetabular height and inclination 12 were also assessed and an attempt was made at the time of reconstruction to match these parameters with that of the contralateral side.

Surgery was undertaken by the senior surgeon in each case. Perioperative antibiotics and anticoagulation were used and in the patient with a history of tuberculosis, antituberculosis medication was employed for 1 month preoperatively and 6 months postoperatively.

A modified Hardinge approach was used in all cases with the patient in the lateral decubitus position. Trochanteric osteotomy was performed in two patients to gain access when required. The trochanter was reattached using the Dall-Miles(TM) cable system (Table 1). Both of these patients had suffered from post traumatic arthritis. Four S-Rom(TM) modular prostheses were implanted and one Stability' prosthesis was used. The Stability prosthesis, which is non-modular, was chosen in the presence of minimal anatomical deformity. An adductor tenotomy was performed on 2 patients postoperatively. Prophylaxis against heterotopic ossification was used in 3 patients (2 patients with fracture dislocations and 1 patient with tuberculous arthritis). Postoperative Indomethacin was used in these patients. Radiotherapy prophylaxis was also employed for 2 patients with prior fracture dislocations in this subset. Preoperative radiotherapy was used in I patient and postoperative radiotherapy used in the other. Clinical information was collected prospectively at follow-up by the treating surgeon.