Background Although the outcomes of total hip arthroplasty (THA) for rheumatoid arthritis (RA) is reported to be comparable with osteoarthritis (OA) patients in terms of fixation of implants, symptoms are often observed in multiple joints in cases of RA, unlike OA. It is assumed that postoperative function of the lower limbs is affected by many factors in RA.
Objectives In this study, RA patients who had undergone THA were retrospectively surveyed to examine the association of the pre- and postoperative function of the hip joint with disease activity of RA, affected joints except operated hip, and severity of destruction of the hip joints.
Methods Out of patients who underwent THA for RA, this study included 25 patients with 31 joints. The subjects were all female. The mean age at the time of surgery was 65.9 years. The preoperative mean values of the 28-joint disease activity score using C-reactive protein (DAS28-CRP), CRP, and the Japanese Orthopedic Association (JOA) score for hip function were 3.12, 2.41 mg/dl, and 39.4 points, respectively. The median Larsen grade of the operated joints was grade 5. The JOA scores were compared between before and one year after surgery, and it was investigated how the JOA scores were correlated with DAS28-CRP, CRP, swollen joint count (SJC), tender joint count (TJC), and Larsen grade. Moreover, the evaluation targeting 44 joints revealed 16 patients with affected joints except operated hip joint in the lower limbs. The JOA scores were compared between the patients with affected joints except operated hip joint and those with no affected joints in the lower limbs.
Results The JOA scores one year after surgery averaged 74.1 points and were improved in all cases. The preoperative JOA scores were negatively correlated with preoperative CRP and DAS28-CRP. However, Larsen grade and the JOA scores were not correlated. Preoperative JOA scores were positively correlated with postoperative JOA scores. Preoperative DAS28-CRP, CRP, and TJC were negatively correlated with postoperative JOA scores. However, there was no correlation between preoperative SJC and postoperative JOA scores. Moreover, the postoperative JOA scores were significantly lower in those with preoperative affected lower limb joints except operated hip joint.
Conclusions Singh JA et al. reported that although there was no significant difference in the improvement of pain, the outcomes for daily activities were significantly worse in the RA patients than in the OA patients. In the present study, the preoperative DAS28-CRP, CRP, and TJC were significantly and negatively correlated with the postoperative JOA scores, indicating that the preoperative disease activity of RA affected the postoperative outcomes. We also demonstrated that the involvement of the other joint of the lower limbs at the time of THA led to poor postoperative function of the hip. RA is an inflammatory disease of multiple joints, unlike OA. In order to improve the surgical outcomes in RA patients undergoing THA, preoperative control of the disease activity of RA, particularly tenderness and treatment of the affected joints of the lower limbs are important.
Disclosure of Interest None declared
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