[Biological total hip arthroplasty combined with impacting bone grafting for the treatment of moderate to severe acetabular invagination secondary to rheumatoid arthritis].

Abstract

Objective: To explore the surgical technique and clinical outcomes of biological total hip arthroplasty(THA) combined with impacting bone grafting for the treatment of moderate to severe acetabular invagination secondary to rheumatoid arthritis(RA).

Methods: Total of 20 patients(28 hips) with RA secondary to acetabular invagination were treated with THA of bioprosthesis combined with autogenous bone grafting from January 2012 to October 2020, including 5 males(8 hips) and 15 females(20 hips) with an average age of (55.10±4.96) years old from 45 to 64 years old. The depth of acetabular invagination was 8.43 to 16.25 mm with an average of (11.91±2.59) mm. According to Sotello-Garza and Charnley classification criterion, there were 15 cases(23 hips) of type Ⅱ(protrusio acetabuli 6 to 15 mm), and 5 cases(5 hips) of type Ⅲ(protrusio acetabuli>15 mm). Autologous femoral head granular bone and(or) allograft impacting grafting were used to reconstruct the acetabum, the biological porous acetabular cup was fixed by pressure fitting. At the postoperative follow-up, the activity function of the hip joint, the length of both lower limbs, VAS and Harris score were evaluated, and the healing of bone graft, the restoration of the hip rotation center and loosening of prosthesis were assessed by X-ray.

Results: The operation time was 75 to 160 min with anverage of (103.32±18.18) min, the intraoperative blood loss was 150 to 650 ml with an average of (319.64±122.61) ml. There were no neurovascular complications during the operation. All patients were followed up from 2 to 10 years with an average of (5.45±2.50) years. The horizontal distance between the center of femoral head and the Kohler's line was increased from (11.40±1.85) mm preoperatively to (25.99±2.56) mm at the final follow-up(P<0.01), and the vertical distance between the center of femoral head and the line joining bilateral ischial tuberosities was decreased from (89.36±5.20) mm preoperatively to (71.84±3.55) mm at the final follow-up(P<0.01). The range of flexion motion of hip joint increased from (44.43±10.57)° preoperatively to (98.75±12.52)° at the final follow-up(P<0.01), the range of abduction motion of hip joint increased from (12.50 ±6.01)°preoperatively to final follow-up (32.82±5.39)°(P<0.01). The discrepancy of both lower limbs was significantly decreased from (19.39±5.93) mm preoperatively to (6.64±2.87) mm at the final follow-up(P<0.01). The VAS decreased from (5.36±0.78) preoperatively to (1.82±0.86) at the final follow-up(P<0.05), and the Harris score increased from (41.39±7.77) preoperatively to (89.00±4.67) at the final follow-up(P<0.01). All the patients could move independently without assistance. Among them, 2 patients(2 hips) had hip pain after exercise, and 1 patient(1 hip) suffered from periprosthetic fracture due to fall.

Conclusion: Autologous femoral head granular bone grafting can reconstruct the acetabulum, and restore the rotation center of the hip joint, combined with biological porous tantalum/titanium acetabular cup can achieve good short-and medium-term outcomes in the treatment of moderate to severe acetabular invagination secondary to rheumatoid arthritis.