Trunk Muscle Strength After Lumbar Spine Fusion: A 12-Month Follow-up.

OBJECTIVE: The aim of this study was to investigate changes in trunk muscle strength 12 months after lumbar spine fusion (LSF) compared to preoperative strength. METHODS: A total of 194 patients (mean±standard deviation [SD] age, 61±21 years) who underwent LSF participated in this prospective longitudinal study. Physical measurements of the participants were made before surgery and 12 months postoperatively. Isometric trunk extension and flexion strength was measured using a strain-gauge dynamometer in the standing position. Strength changes were calculated. Regression analysis was performed to explore which factors predicted strength levels at 12 months postoperatively. RESULTS: The preoperative mean±SD extension strength was 205±144 N, which increased to 258±142 N (p<0.001) at the 12-month follow-up. Flexion strength increased from 295±172 N to 364±164 N (p<0.001). The preoperative extension/flexion strength ratio was 0.75±0.38 and remained similar (0.73±0.26) at 12 months postoperatively (p=0.39). CONCLUSION: Although trunk muscle strength increased by 26% for extension and 23% for flexion at the 12-month postoperative follow-up, both values remained objectively low. In addition, flexion strength remained higher than extension strength, which indicates an imbalance between those muscle groups. Age, severe back pain, and low trunk muscle strength before surgery predicted low trunk muscle strength at 1 year after spinal fusion.

Decreased muscle strength and mobility of the neck in patients with rheumatoid arthritis and atlantoaxial disorders.

OBJECTIVE: To compare neck muscle strength and mobility of the cervical spine in rheumatoid arthritis (RA) patients with and without atlantoaxial (AA) disorders (anterior atlantoaxial subluxation [AAS], AA impaction). DESIGN: Clinical cross-sectional study. SETTING: Outpatient rheumatology and rehabilitation clinics in a Finnish hospital. PARTICIPANTS: Patients with RA (N=124; mean age +/- standard deviation, 62+/-12y [corrected]) on a waiting list for orthopedic surgery. Thirty (24%) patients presented with AA disorders (16 with anterior AAS, 8 with AA impaction, 6 with a combination of anterior AAS and AA impaction). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Neck function was measured by isometric neck strength and mobility tests, neck pain by a visual analog scale, erosion of the hands and feet by radiography, and the patients' function by the Health Assessment Questionnaire (HAQ). RESULTS: Maximal neck muscle strength against flexion, extension, and rotation was lower in patients with AA disorders compared with the other patients in both women (P=.012) and men (P=.017). Mobility was lowest in the AA impaction group in all measured directions (P<.001). Peripheral erosive disease was more frequent in the group with AA disorders. They also had longer disease duration and were more disabled (HAQ) than the other patients. CONCLUSIONS: Neck muscle strength is significantly decreased in patients with AA disorders. Mobility of the cervical spine is most limited in patients with AA impaction, but can be normal in cases with solitary anterior AAS.

Early and extensive erosiveness in peripheral joints predicts atlantoaxial subluxations in patients with rheumatoid arthritis.

OBJECTIVE: To study the prevalence of cervical spine subluxations and predictive factors for atlantoaxial subluxations (including anterior atlantoaxial subluxation and atlantoaxial impaction, i.e., vertical subluxation) in patients with rheumatoid arthritis (RA) who were treated early and continuously with disease-modifying antirheumatic drugs for 8-13 years. METHODS: Radiographs of the cervical spine were obtained in 103 of 110 patients (the 110 surviving patients of the original 135-patient cohort) at their 8-13-year followup visits. The prevalence of cervical spine subluxations was determined. Demographic variables and the first 5-year serial data concerning disease course were analyzed in a logistic regression model to find predictive factors for atlantoaxial subluxations. RESULTS: Atlantoaxial subluxations were found in 14 patients (14%), and 5 patients (5%) had subaxial subluxations. Older age at baseline, greater disease activity during the first 5 years, and early erosiveness in peripheral joints predicted the development of atlantoaxial subluxations. Patients who had >or=10% of the maximum possible radiographic damage (by Larsen score) in peripheral joints at 5 years were 15.9 times more likely to develop atlantoaxial subluxations at 8-13 years than patients whose peripheral joint damage remained <10% of the maximum. CONCLUSION: Compared with historical control RA cohorts, a lower prevalence of cervical spine destruction was found in the present group of patients. Rapid erosiveness in peripheral joints was the best predictor for atlantoaxial subluxations. Extensive erosiveness in peripheral joints should alert rheumatologists to the possible development of atlantoaxial subluxations in patients with RA.