Total Knee Replacement in Patients with Lumbar Spinal Fusion Leads to Significant Changes in Pelvic Tilt and Sacral Slope
2Orthopedic surgery, Sheba "Tel-Hashomer" Medical Center, Israel
3Orthopedic Surgery, Ichilov "Sourasky" Medical Center, Israel
Background:
The knee-hip-spine syndrome has been well elucidated in the literature in recent years. The aim of this study was to evaluate the effect of total knee replacement (TKR) on spinopelvic sagittal alignment and to determine whether patients with pre-TKR lumbar spinal fusion develop more substantial changes in sagittal alignment than those without spinal fusion.
Methods:
This is a retrospective cohort study of 113 patients who underwent TKR for primary osteoarthritis. Patients were stratified into the following three groups: (1) patients who had pre-TKR spinal fusion (SF, n=19), (2) patients who had no spinal fusion but experienced pre-TKR flexion contracture (FC, n=20), and (3) patients without flexion contracture or spinal fusion before TKR (no SF/FC, n=74). Spinopelvic sagittal alignment parameters, including pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and plumb line-sacrum distance (SVA) were measured preoperatively and 3 months postoperatively on whole-body standing EOS imaging.
Results:
TKR resulted in significant pre- to postoperative changes in pelvic tilt (average ∆ PT = 8.6°, p=0.018) and sacral slope (average ∆ SS= -8.6°, p=0.037) in the spinal fusion (SF) group. Although minor changes in spinopelvic sagittal alignment parameters (PT, SS, LL, TK, SVA) were noted postoperatively in all patients with flexion contracture (FC) alone or in those without preoperative flexion contracture or spinal fusion (no SF/FC), none of these changes were statistically significant.
Conclusion:
Total knee replacement can lead to meaningful changes in spinopelvic alignment in patients with prior lumbar fusion compared to those without spinal fusion. Patients with spinal fusion who are candidates for both hip and knee replacements should consider undergoing TKR first since changes in spinopelvic sagittal alignment can increase the risk of complications such as hip dislocations and result in worse patient-reported outcomes.