Resident Physician University of South Florida Tampa, Florida, United States
Introduction: Currently there is a vast amount of research in the spinal literature about adjacent segment disease. In addition, changes are noted in the sacro-iliac joints after thoracolumbar instrumentation. However, there appears to be a lack of knowledge in the neurosurgical literature as it relates to pelvic instrumentation with long spinal fusions for adult spinal deformity (ASD) surgery and changes to the femoroacetabular joint. Our orthopedic colleagues have the luxury of obtaining extensive training on hip pathology during their residency and training. This familiarity with hip biomechanics and pathology is something that we are lacking in neurosurgical training. We believe that it is vital to better understand the biomechanical changes occuring in the hip after long fusion constructs as many patients go on to develop hip arthropathy, so that we may better educate our patients and guide them through their treatment.
Methods: Patients who underwent ≥ 4-level fusion to the sacrum using iliac screws or S2AI screws for adult spinal deformity who completed a 2-year postoperative standing scoliosis X-ray scan were included in the present study. Two year post op standing scoliosis films were used to measure the distance between the femoral head and the acetabulum. Two groups were compared, those with UIV in the lumbar spine and the other located in the thoracic spine.
Results: During the review of our patient population we found that 148 patients could be included in this study. The lumbar UIV instrumentation group had a total of 49 patients, with a pre-op mean measurement of 6.13 mm. For this same group the postoperative measurement at two years follow up had mean value of 5.24 mm, giving it an average change of 0.9mm. Between the two groups we found no statistical significance between number of levels fused and the anatomic changes between pre-op and post-op measurements of the femoroacetabular joint space on standing scoliosis films at 2 years post op.
Conclusion : Further studies will need to be conducted to further understand the anatomic changes resulting in hip pathology after long level fusions in the spine that inevitably are transmitted into the acetabulum and down into the femoral head.
