Quantifying the effects of degeneration and other patient factors on lumbar segmental range of motion using multivariate analysis.

Study Design: Retrospective review and multivariate analysis.

Objectives: Assess lumbar spine segmental range of motion (ROM) with flexion/extension (F/E) radiographs and determine the relation to clinical variables.

Summary Of Background Data: Prior studies have investigated the roles of age and degeneration on lumbar segmental ROM only using univariate analyses. Multivariate analyses are also required to differentiate the multiple factors that may affect ROM and quantify their relative effects.

Methods: Radiographs of 258 patients were analyzed, including 137 females and 121 males with ages ranging from 18 to 92 years. Segmental ROM and Kellgren score (KS) of degeneration were assessed for L1-S1. Multivariate regression analyses were performed for each level. Predicting variables evaluated were: (1) KS at the level of interest, (2) KS at the level above, (3) KS at the level below, (4) age, (5) gender, (6) weight, (7) height, (8) body mass index (BMI), and (9) smoking. Significance was defined as P < 0.05.

Results: Interobserver reliabilities for assessing KS (ICC 0.70) and segmental ROM (ICC 0.80) were good to excellent. In the multivariate analyses, age had a significant negative association with ROM at L1-L2, L2-L3, L3-L4, and L4-L5. BMI had a significant negative association with ROM at L2-L3, L3-L4, and L4-L5. KS at the level of interest had significant negative association with ROM only at L5-S1. KS at adjacent levels, gender, weight, height, and smoking did not have a significant association with ROM at any level.

Conclusion: The results of this study provide the clinician with insight into factors that influence segmental lumbar ROM. Age was the strongest statistical predictor of ROM and was associated with declining ROM, amounting to an approximate 3 degrees decrease in total sagittal lumbar ROM in the superior 4 segments every 10 years. BMI was another factor associated with lumbar ROM. Degeneration was a significant predictor of ROM only at L5-S1.