Abstract
BackgroundThere is a paucity of reports clarifying the implication of knee osteoarthritis (OA) on spinal sagittal alignment of patients undergone surgery for lumbar spine. This study aimed to analyze how osteoarthritic knee affects radiographic and clinical results of degenerative lumbar disease patients undergone lumbar fusion.MethodsWe retrospectively reviewed the medical records and radiographs of 74 consecutive degenerative lumbar disease patients who underwent posterior instrumentation and fusion surgery between May 2016 and June 2017 and were followed up for minimum 3 years postoperatively. The patients were divided into 2 groups according to the severity of knee OA by Kellgren-Lawrence grading (KLG) scale (group I, KLG 1 or 2 [n = 39]; group II, KLG 3 or 4 [n = 35]). Patient demographic data, comorbidities, spinal sagittal parameters and clinical scores were extracted and compared at preoperative, postoperative 1 month and the ultimate follow-up between the groups. In radiographic assessment, sagittal alignment parameters and sagittal balance were used. In clinical assessment, the scores of Oswestry disability index (ODI) and Scoliosis Research Society questionnaire (SRS-22) were used. For the frequency analysis of categorical variables across the groups, chi-square test was used and student t tests was used to compare the differences of continuous variables.ResultsIn radiographic assessment, TLK (thoracolumbar kyphosis), LL (lumbar lordosis), PT (pelvic tilt), C7 SVA (sagittal vertical axis) in both groups improved significantly after surgery (p < 0.05). However, LL, PT, C7SVA improved at postoperative 1 month in the group II were not maintained at the ultimate postoperative follow-up. In clinical assessment, preoperative Oswestry disability index (ODI, %) and all SRS-22 subscores of the group I and II were not different (p > 0.05). There were significant differences between the groups at the ultimate follow-up in ODI (− 25.6 vs − 12.1, p < 0.001), SRS total score (%) (28 vs 20, p = 0.037), function subscore (1.4 vs 0.7, p = 0.016), and satisfaction subscore (1.6 vs 0.6, p < 0.001).ConclusionOsteoarthritic knee with KLG 3 or 4 have a negative influence on maintaining postoperative spinal sagittal alignment, balance, and the clinical outcomes achieved immediately by posterior instrumentation and fusion for lumbar degenerative disease.Trial registrationThis study was retrospectively registered with approval by the institutional review board (IRB) of our institution (approval number: 2018–11-007).
Highlights
There is a paucity of reports clarifying the implication of knee osteoarthritis (OA) on spinal sagittal alignment of patients undergone surgery for lumbar spine
Study design & patient population After obtaining informed consent from each patient and approval by the institutional review board (IRB) of our institution, a retrospective study was performed on 74 consecutive patients between the age of 55 to 75 with degenerative lumbar disease treated by decompression and instrumented interbody fusion between May 2016 and June 2017 at a single institution
Clinical assessment To evaluate clinical outcomes, we reviewed and used the Oswestry disability index (ODI) scores, Scoliosis Research Society (SRS-22) questionnaire at the preoperative, the postoperative 1 month and the ultimate follow-up
Summary
There is a paucity of reports clarifying the implication of knee osteoarthritis (OA) on spinal sagittal alignment of patients undergone surgery for lumbar spine. This study aimed to analyze how osteoarthritic knee affects radiographic and clinical results of degenerative lumbar disease patients undergone lumbar fusion. There are still no definite studies investigating knee joints’ effect on spinopelvic alignment, Tsuji et al [3] introduced the knee-spine syndrome: phenomenon of thigh muscle tightness and knee flexion leading decreased lumbar lordosis and sacral inclination while standing in elderly Japanese. Because motion of the knee joint has such a significant impact on the biomechanics of sagittal balance, it is required to understand the effect of knee OA on the outcomes of patients who undergo spinal fusion surgery
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