Background Little is known about total joint arthroplasty (TJA) in dermatomyositis (DM) and polymyositis (PM), although patients are at risk for osteonecrosis from corticosteroid use.
Objectives To describe total knee (TKA) and total hip (THA) arthroplasty in DM/PM.
Methods We identified 8 patients with DM/PM enrolled in an institutional arthroplasty registry between 2007 and 2011. The diagnosis was validated with medical record review. Self-report, physical therapy, and administrative data were collected. These patients were compared with a convenience sample of gender-matched osteoarthritis controls undergoing similar procedures. Outcomes were evaluated through 1/2014.
Results 8 patients underwent 11 procedures during the study period: 5 patients had 5 TKA and 3 patients had 6 THA. 1 patient met Bohan criteria for definite DM/PM, 5 probable, and 2 possible. Patients with DM/PM had poorer post-operative progress with physical therapy, particularly in activities where proximal strength was important. DM/PM patients were less likely to climb stairs by the day of discharge (p-value=0.002) and were 2x less likely to achieve pre-determined physical therapy goals (p-value=0.01). There was no difference in level distance walked (17.3 ft vs. 23.08, p-value=0.87). Osteonecrosis was present in 7 joints. Post-op, 2 TKA patients required manipulations, and 1 required revision for pain and poor function at 39 months. 1 THA patient who had both hips replaced underwent revision for a prosthetic joint infection at 5 months and a subsequent contralateral THA revision for recurrent dislocation at 41 months. For OA, there was 1 manipulation and 1 revision. No patients had any cardio-pulmonary complications prior to discharge. 2 DM/PM patients with 2-year self-report data showed similar pain and function as the OA controls.
Conclusions In this small cohort of DM/PM patients, 25% of prosthesis was revised within 3.5 years. DM/PM patients appear slower to meet post-operative rehabilitation goals than OA patients. Whether this is due to proximal muscle weakness is not known. Although not usually proscribed, this may be a unique patient group in which pre-operative muscle strengthening is indicated. Although limited by the retrospective study design and missing data, to our knowledge this is the only known report on the outcomes of TJA in DM/PM.
Disclosure of Interest None declared