Total hip arthroplasty in treating acetabular protrusion secondary to rheumatoid arthritis / 中华骨科杂志

ABSTRACT

Objective To investigate the clinical outcomes of total hip arthroplasty in treatment of severe acetabular protrusion secondary to rheumatoid arthritis.Methods From January 2011 to November 2014,eighteen patients (20 hips) with severe acetabular protrusion secondary to rheumatoid arthritis were treated with total hip arthroplasty (THA),including 6 males (6 hips) and 12 females (14 hips).The age ranged from 37 to 68 years (average,45.8±8.3 year).According to the classification of Sotelo-Garza and Charnley,there were 15 cases (17 hips) of type Ⅱ (acetabular protrusion 6-15 mm) and 3 cases (3 hips) of type Ⅲ (acetabular protrusion ＞ 15 mm).During the surgery,the femoral heads were moved out through retrograde method after the osteotomy of femoral neck by posterolateral approach.All patients underwent THA with autogenous bone graft by impacting technique for reconstruction of acetabula,and the cementless cups were planted with press-fit skills (Tantalum trabecular metal cup in 16 cases and Titanium porous coating cup in 4 cases).The hip function was evaluated by using Harris hip score.Radiographic measurement was performed with X-ray films to assess the restoration of the hip rotation center,graft incorporation and sign of prostheses loosening in follow-up duration.Results The mean operation duration and intraoperative blood loss were 89.5±8.1 min (range 55-131 min) and 295±10.9 ml (range 165-480 ml) respectively.The average amount of bone graft was 33.7±6.8 cm3 (range 32.5-61.2 cm3) in reconstruction of protrusion acetabulum.The mean follow up duration was 4.5± 1.7 years (range 2.5-6.0 years).The horizontal distance between the center of femoral head and the Kohler's line was increased from preoperative 8.87±3.9 mm (range-11.11-12.78 mm) to 23.55 ± 2.5 mm (range 21.23-25.57 mm) postoperatively,and the vertical distance between the center of femoral head and the line joining the bilateral ischial tuberosities was decreased from preoperative 87.45 ± 3.5 mm (range 74.75-96.97 mm) to postoperative 77.83±4.1 mm (range 68.22-90.40 mm) with statistically significant difference.The bone incorporation was achieved at 6 months postoperatively in radiological film.No loosening of acetabular components was found in final fellow-up.At last follow-up,Harris hip score was significantly improved from 55.3±9.5 points preoperatively to 92.2±12.7 postoperatively (t=51.569,P=0.000).The range of flexion of the hip significantly improved from 41.5°±6.7° preoperatively to 102.3°±14.5° at finial follow-up (t=64.865,P=0.000),and the range of extension of the hip improved from 8.2°±3.5° preoperatively to 29.8°±6.6° at finial follow-up (t=51.161,P=0.000).The discrepancy was significantly decreased from 23.7±0.82 mm preoperatively to 4.7±0.39 mm postoperatively (t=19.761,P=0.000).Mild thigh pain was reported in two hips,which typically occurred only with prolonged activity without disabling and not requiring medication.Conclusion Total hip arthroplasty with impaction bone grafting and cementless modular cup can recover the acetabular center of rotation and achieve satisfactory short-term outcomes in treating patients severe protrusion acetabula secondary to rheumatoid arthritis.