O3252: The Value of Intra-articular Corticosteroid Injection in Predicting Pain Relief Following Periacetabular Osteotomy

Background: Acetabular dysplasia is characterized by deficient acetabular coverage of the femoral head with associated joint instability, leading to overloading of the weight-bearing surface, cartilage damage, and premature osteoarthritis (OA). Periacetabular osteotomy (PAO) is a powerful surgical intervention for skeletally-mature patients to reorient the acetabulum and improve femoral head coverage. While intra-articular corticosteroid injection (CSI) is commonly used for therapeutic and diagnostic purposes in hip pathologies, its predictive value prior to PAO in acetabular dysplasia patients remains unclear. This study aims to assess the relationship between self-reported preoperative pain relief from intra-articular CSI and postoperative pain relief following PAO.

Methods: The case log of a single hip preservation surgeon at a tertiary-care children’s hospital was queried from 2013 onward for patients with acetabular dysplasia undergoing PAO surgery. All patients with preoperative intra-articular CSI were included. Those with comorbid neuromuscular diagnoses or non-dysplasia indications for PAO were excluded. Patients were asked “overall, what percent improved (or worsened) are your symptoms on a scale from 0-100%?” at the first clinical visit following CSI and each post-operative visit starting 3 months following PAO. We defined a successful postoperative pain outcome as pain relief ≥75% compared to preoperative symptoms at the approximate 6-month postoperative visit. Clinical exam and radiographic measurements were collected both pre- and post-operatively.

Results: 76 hips met inclusion criteria. The majority of the cohort was female (97%), and mean age was 21.1±6.23 years. Mean reported percentage relief from preoperative intra-articular CSI was 69.9±35.2%. Mean postoperative pain relief was 88.2±18.1%, with 66 patients (86.8%) achieving successful postoperative pain relief (i.e. ≥75%). Regression analysis showed a positive correlation between preoperative CSI relief and postoperative pain relief (0.318, p=0.005). ROC curve analysis found ≥60% pain relief from CSI to be the optimal threshold for predicting a successful postoperative pain outcome using the Youden index. 93% of patients with pain relief ≥60% after preoperative CSI achieved successful postoperative pain outcomes, in comparison to 71% of patients with < 60% preoperative CSI pain relief (p=0.023). The PPV remained high and the NPV remained low over a wide range of potential CSI relief thresholds (Figure 1).

Conclusion: Identifying the source of pain in acetabular dysplasia patients and predicting their potential PAO relief is a complex process. Although CSI remains important in diagnosis, the current study finds CSI relief largely fails to discriminate between patients with poor postoperative outcomes and the rest. NPV associated with any CSI pain relief threshold remained low, largely due to only 10 patients (13.2%) failing to achieve successful postoperative relief in the entire series. As our patients generally experienced significant postoperative pain relief regardless of preoperative CSI response, further work to identify those unlikely to benefit from surgery is warranted.