The Relationship Between the Lumbar Stiffness Disability Index and Trunk and Hip Joint Range of Motion After Spinal Fusion Surgery

It is considered that ADL limitations due to subjective lumbar stiffness may be related not only to trunk ROM but also to hip joint ROM. In this study, we aimed to clarify the factors associated with the LSDI from the perspectives of physical functions, including ROM of trunk and hip joint.

The inclusion criteria were Japanese-speaking adult patients after spinal fusion surgery. Surgical indications included lumbar canal stenosis and adult spine deformity. Patients undergoing spinal surgery for cancer, infection, or trauma and those who could not read were excluded. The evaluation items included: 1) basic attributes (age, sex, BMI, postoperative period), 2) trunk ROM (flexion and extension), 3) hip ROM (flexion, abduction, adduction, external rotation, internal rotation), 4) 30-second chair stand test (CS30), 5) Functional Reach Test (FRT), and 6) the Japanese version of the Lumbar Stiffness Disability Index (J-LSDI). Trunk ROM was measured using a dual inclinometer, capturing the change from the standing position to the maximum flexion or extension position. Hip ROM was measured using a goniometer. The J-LSDI was created in accordance with the guidelines for cross-cultural adaptation. Statistical analysis was performed using Pearson correlation coefficient to examine the relationship between J-LSDI and physical functions. Additionally, multivariate analysis (stepwise method) was conducted to assess the strength of these relationships with a significance level set at 5%. 

There were 145 females, 58 males. The mean age was 70.4 years (range 40–89), and the mean follow-up was 27.9 months (range 3–146). The mean number of fusion levels was 3.6±3.6 (range 1–16). There were significant correlations between the J-LSDI and trunk flexion ROM (r＝-0.58), trunk extension ROM (r＝-0.49), hip flexion ROM (r=-0.48), hip external rotation ROM (r＝-0.48), hip abduction ROM (r＝-0.32), hip adduction ROM (r＝-0.19), FRT (r＝-0.43) and CS30 (r＝-0.41). Multiple regression analysis showed that the J-LSDI was significantly associated with trunk flexion ROM (B=-0.34, β=-0.34), hip flexion ROM (B=-0.25, β=-0.19), hip external rotation ROM (B=-0.25, β=-0.17), and FRT (B=-0.47, β=-0.19) (adjusted R² = 0.43).

ADL limitations due to lumbar stiffness were associated with not only the range of motion in trunk flexion ROM but also hip flexion ROM and hip external rotation ROM, as well as forward reach balance function. 

These results are considered to be helpful in guiding physical therapy interventions aimed at improving ADL limitations caused by lumbar stiffness.