Progression of cervical instabilities in patients with rheumatoid arthritis 5.7 years after their first lower limb arthroplasty.

We reviewed 101 rheumatoid arthritis (RA) patients who had undergone their first lower limb arthroplasty between 1990 and 2002. None of the patients had received immunosuppressant or biological drugs. Preoperative and follow-up cervical spine radiographs had been performed (more than 2 years after the arthroplasty). Cervical spine instabilities were found in 62 and 82 patients, and a posterior atlantodental interval (PADI) of <14 mm was present in 20 and 22 patients in the respective radiographs. The presence of cervical spine instabilities and PADI <14 mm were correlated with a higher modified Lansbury index (LI) both preoperatively and at final follow-up. Patients with no cervical spine instability throughout the follow-up had a lower average LI. Patients with atlantoaxial subluxation (AAS), vertical subluxation (VS), and subaxial subluxation (SAS) had more joint arthroplasties at final follow-up compared with other patients. The percentage of patients with single and multiple cervical instabilities increased at final follow-up. The incidence of cervical spine instabilities in RA patients requiring a lower limb arthroplasty is extremely high, with progression of these instabilities after the procedure. There is a correlation between the severity of RA activity in peripheral joints and the severity of cervical spine instabilities.