Hydroxyapatite coated Total Hip Arthroplasty in Rheumatoid Arthritis

Choi, Il Yong; Kim, Young Ho; Lee, In Mook; Shon, Jeong Hwa; Kim, Tae Jin

Abstract

Rheumatoid patients have poor bone quality and also have an increased incidence of sepsis, delayed wound healing, and general overall complications. It is the purpose of this paper to assess the clinical and roentgenographic results of ABG total hip replacement in rheumatoid arthritis. Twenty-six total hip arthroplasties done in seventeen patients with rheumatoid arthritis were studied prospectively. The average follow-up was 3 years and 4 months, with a minimum follow-up of 2 years and 7 months. The average age of the patients was 49.7 years (range 36-63) and there were sixteen females and one male. All patients fulfilled the 1987 revised criteria and there were eleven cases of protrusio acetabuli. All patients except two were taking oral steroids, nineteen cases were classed as Singhs index 1, five cases as Singhs index 2, and two cases as Singhs index 3. The Charnley approach with a trochanteric osteotomy was employed in all patients. Cup fixation was achieved with two spikes in twenty-one cases, two spikes and one screw in five cases, and in all cases the acetabular cup was angled at less than 45 from the horizontal. There was a gap between the acetabular cup and the acetabulum at DeLee and Charnley zone 1 in three cases, and at zone 2 in six cases. At 2 years, there was no radiolucency, reactive line or any sign of bone resorption. The development of cancellous and cortical densification was seen in Gruen's zone 2 and 6 for the first time in the 1 year radiographs. It became more prominent in the 2 year radiographs. The reactive bone line first became visible at the 6 month follow-up in the Gruen's zone 3 and 5. These lines extended more proximally, but it did not involve the proximal HA coated portion. Cortical hypertrophy of diaphysis was seen at Gruen's zone 3 and 5 in five cases. Rounding off of calcar was visible at zone 7 in six cases. There were no radiological changes of the femoral side in fourteen cases and the acetabular side in seven cases. There was one case of wire breakage, one case of trochanteric separation, and one case of intraoperative splitting of calcar. The result of the study indicated that the development of osseointegration in rheumatoid arthritis might be slow, but the clinical and radiological results were satisfactory. Further prospective follow up is necessary to determine whether the favorable early result of HA coated implant are maintained over longer periods.