Posterior quadratus lumborum block, a novel approach to treat chronic hip pain: a cohort study.

Background: Hip osteoarthritis is a common disease, and the pain associated with it has a major impact on morbidity and quality of life. Therefore, the management of chronic hip pain requires a multimodal approach to improve joint function and quality of life. The aim of this study was to assess whether the posterior quadratus lumborum block (QLB) reduced pain and enhanced quality of life in patients suffering from chronic pain.

Methods: After Ethical committee's approval (no. PI 21-PI104 on June 26,2021) and registration (Trial registration number: NCT04438265) we started this prospective cohort study. The sample size calculated were 200 patients (100 per group) suffering from chronic hip pain with poor response to previous treatments. The intervention group received posterior quadratus lumborum block as an analgesic technique and control group did not. Pain (NRS) and quality of life (WOMAC questionnaire) were assessed at baseline, three weeks, three and six months in both groups.

Results: Demographic data showed no differences between groups. The QLB group showed significant improvements in pain and quality of life at three months compared to baseline (NRS mean 7/4; and WOMAC mean 59/35) (P value=0.001), while the control group scores remained unchanged (NRS 7/8; and WOMAC (61/61). At three months, 50 patients in the QLB group showed an improvement more than 50% in NRS and WOMAC scores (ten of those patients had an improvement for more than one year). We observed that patients with avascular necrosis showed a minor improvement. Only two adverse events were registered.

Conclusions: Our results suggest that posterior QLB could represent a minimally invasive option in chronic hip pain.