To assess the relationship between spinopelvic parameters changes and low back pain (LBP) improvement in patients with severe unilateral primary hip osteoarthritis (HOA), before and after total hip replacement (THR)

From January 2015 to may 2016, 91 patients ( 47 with and 44 without concomitant low back pain) with unilateral HOA (grade 6 or 7 according to Turmezei and Harris hip score) underwent clinical and radiological evaluation, before and 6 months after THR. Full spine standing anteroposterior and lateral x-rays were obtained. The evaluated spinopelvic parameters were: thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA) [Fig.1], T1-spinopelvic inclination (T1Spi), T1 pelvic angle (TPA) [Fig. 2], pelvic incidence (PI), pelvic tilt (PT) and sacral...

At baseline, symptomatic patients had a higher LL, SS, PI, SVA(C7) and a lower PT and T1-SPI compared to non symptomatic ones. Six months after THR in the first group significant spinopelvic alignment changes were observed, in particular a reduction of SS (p=0.0001), LL (p=0.007), TPA (p=0.028) and SVA(C7) (p=0.0086) and an increment of PT (p=0.0001), while in the second group no statistically significant changes were recorded.

The clinical interest about the interdependence between the spine and the pelvis is progressively increased over the last few years. However, contrasting findings have been reported in different studies, so the mechanism for hip-spine syndrome remains still unclear. In our experience, spinopelvic misalignment was observed in patients suffering of severe unilateral HOA and LBP compared to non symptomatic patients. According to us, it reflects an antalgic posture developed by the patients to keep the spine as vertical as possible, as it was not related to...

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