Younger Patients Are Differentially Affected by Stiffness-Related Disability Following Adult Spinal Deformity Surgery

Objective: The Lumbar Stiffness Disability Index (LSDI) assesses impact of lumbar stiffness on activities of daily living. We hypothesized that patients <60 years old would perceive greater lumbar stiffness–related functional limitation following fusion for adult spinal deformity. Methods: Patients completed the LSDI and Scoliosis Research Society 22 Questionnaire, Revised (SRS-22r) preoperatively and at 2 years postoperatively. The primary independent variable was patient age <60 versus ≥60. Multivariable regression analyses were used. Results: Analysis included 267 patients. Patients <60 years old (51.3%) and ≥60 years old (48.7%) were evenly represented. In bivariable analysis, patients age <60 exhibited lower LSDI at baseline versus patients age ≥60 (25.7 vs. 35.5, β −9.8, P < 0.0001), but a directionally smaller difference at 2 years (26.4 vs. 32.3, β −5.8, P = 0.0147). LSDI was associated with lower SRS-22r total score among both age groups at baseline and 2 years (all P < 0.0001); the association was stronger among patients age <60 versus ≥60 at 2 years. LSDI was associated with SRS-22r satisfaction scores at 2 years among patients age <60 (P < 0.0001), but not patients age ≥60 (P = 0.2250). The difference in SRS-22r satisfaction per unit LSDI between patients <60 years old and ≥60 years old was significant (P = 0.0021). Conclusions: Among patients with adult spinal deformity managed operatively, higher LSDI was associated with inferior SRS-22r total score and satisfaction at 2 years postoperatively. The association between increased LSDI and worse patient-reported outcome measures was greater among patients age <60 versus ≥60. Preoperative counseling is needed for patients age <60 undergoing adult spinal deformity surgery regarding effects that lumbar stiffness may have on postoperative function and satisfaction.