Patients With Low-Grade Lumbosacral Transitional Vertebrae Demonstrate No Difference in Achievement of Clinical Thresholds After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

Abstract

The purpose of our study was to compare clinical outcomes at 2 years following primary hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) between patients with and without low-grade lumbosacral transitional vertebra (LSTV). We performed a retrospective matched-cohort analysis of patients who underwent primary HA for FAIS from 2011-2018 with minimum 2-year follow-up. LSTV was graded on preoperative radiographs using the Castellvi classification. Patients with grades I and II LSTV were matched 1:1 with controls on age, sex, and BMI. Radiographic markers of FAIS morphology were measured. Pre-to-postoperative improvement in the modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS), and 2-year achievement rates for the Minimum Clinically-Important Difference (MCID), Substantial Clinical Benefit (SCB), and Patient Acceptable Symptom State (PASS) were compared between patients with versus without LSTV. The Wilcoxon signed-rank test was used for intergroup mean comparisons and the Cochran-Mantel-Haenszel test for categorical variables. 58 patients with LSTV were matched to 58 controls. Among LSTV patients, 48 were Castellvi type 1 (82.8%) and 32 (55.2%) had bilateral findings. No significant differences were found between groups with respect to radiographic markers of FAIS, including alpha angle (p=0.88), lateral center edge angle (LCEA) (p=0.42), or crossover sign (p=0.71). While LSTV patients had greater improvement in NAHS at 2-year follow-up compared to controls (p=0.04), there were no significant differences in mHHS improvement (p=0.31) or achievement of the MCID (p=0.73), SCB (p=0.61), or PASS (p=0.16). Patients with low-grade LSTV had greater 2-year improvement in NAHS than controls, while no significant differences were observed in achievement of clinical thresholds at 2-year follow-up. There were no differences between groups with respect to any measured radiographic markers of FAIS morphology. Importantly, the findings of this study are underpowered and should be viewed with caution in the greater context of the LSTV literature. III; Retrospective comparative study.