Study Design: The effect of Total Hip Replacement surgery (THR) upon spinal sagittal alignment and low back pain was assessed in patients with severe hip osteoarthritis.

Summary of Background Data: Osteoarthritis in the hip joint is associated with abnormal posture and gait due to hip flexion contracture and hip pain. This in turn may cause abnormal spinal sagittal alignment and secondarily induce low back and leg pain. However, there have been no reports regarding the corrective effect of Total Hip Replacement surgery upon spinal sagittal alignment in patients with osteoarthritis of the hip.

Methods: This study prospectively analyzed the results of 25 patients (15 females and 10 males, average age 67.4 years (32–84)) undergoing THR for severe osteoarthritis of the hip. Pre and post-surgical assessment included; sagittal measurement of Sacral Inclination (SI) and total Lumbar Lordosis (L1-S1) on standing lateral radiographs. Functional clinical outcomes for hip as well as low back were also evaluated using the Oswestry back Questionnaire, the Modified Harris Hip Score and Visual Analog Scale for lower back pain and hip pain accordingly.

All the radiographic and clinical evaluations were completed both before THR surgery and 3 months following the surgery during routine follow up.

Results: Mean Lumbar Lordosis before the surgery and in the follow up was 50.36 and 50.32 respectively. Mean sacral inclination before and after surgery were 39.06 and 38.16 respectively. Mean Functional outcomes as assessed by the HHS score before and after the surgery were 45.74 and 81.8 respectively. Mean Oswestry Questionnaire scores before and after the surgery were 36.72 and 24.08 respectively. Mean VAS scores for hip pain before and after the surgery were 7.08 and 2.52 respectively. Mean VAS scores for lower back pain before and after the surgery were 5.04 and 3.68 respectively.

Discussion: No Significant difference was found between the sagittal alignment of the spine before THR and 3 months following it. Interestingly, total hip replacement surgery significantly improved spinal functional outcome as well as relieved low back and hip pain.