Optimizing lordosis preservation in monosegmental lumbar spondylodesis: evaluating the efficacy of a novel noninvasive technique using intraoperative hip hyperextension.

Abstract

Background: Loss of lumbar lordosis after spinal fusion can lead to complications such as chronic low back pain, abnormal sagittal balance, and accelerated adjacent segment degeneration. This study aims to evaluate a novel intraoperative positioning technique for lumbar spondylodesis, involving hip hyperextension in the prone position with an inflatable bladder under the thigh to preserve lumbar lordosis.

Materials and methods: This prospective, pilot, interventional study included 100 patients undergoing monosegmental lumbar fusion at L4 or L5. Patients with degenerative disc disease and no prior spine surgery were enrolled. Lateral X-rays were obtained preoperatively, intraoperatively, and postoperatively, measuring sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), and distal lordosis (DL). Spine types were categorized using the Roussouly classification. Data were analyzed using multivariate regression, accounting for age, body mass index (BMI), and spine type, with subgroup and sensitivity analyses.

Results: The mean patient age was 68.1 years, with 54% classified as overweight (mean BMI: 26.6 kg/m²). Significant improvements in distal lordosis were noted: preoperative (16.68° ± 8.85), intraoperative before reduction (17.60° ± 8.80), after reduction (21.44° ± 10.19), and postoperative (22.23° ± 10.13) (Z = -7.757, p < 0.005). The Sacral Slope increased postoperatively by 2.67° [t(99) = 2.671, p = 0.009]. The hip hyperextension technique improved lordosis independently of age, BMI, and spine type (p < 0.05). Patients with higher BMI (p < 0.01) and Roussouly type 3 (p < 0.05) benefited the most.

Conclusions: This study introduces a novel positioning technique that effectively preserves lumbar lordosis during spinal fusion without additional implants or complex procedures. The technique shows promise for optimizing outcomes and warrants further investigation with larger cohorts and extended follow-up. Trial Registration Retrospectively registered with the institutional ethics committee (Approval No. F-2023-073). Informed consent was obtained from all participants. Level of Evidence Level IV, case series.