Preoperative Temporal Summation is Associated with Impaired Recovery Following Hip Arthroscopy for Femoroacetabular Impingement Syndrome .

Objectives: Chronic pain is a risk factor for worse outcomes following hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Pain sensitization involves the central nervous system perceiving previously innocuous stimuli as noxious. Temporal summation can provide a surrogate measure of sensitization, and may be a clinical tool to identify patients at a higher risk for poor post-hip arthroscopy outcomes. Therefore, we aimed to 1) identify the prevalence of temporal summation in patients undergoing hip arthroscopy for FAIS, 2) determine if there a difference in postoperative improvement between individuals with and without preoperative temporal summation, and 3) examine preoperative predictors of poor postoperative recovery.

Methods: 51 participants undergoing hip arthroscopy for FAIS underwent preoperative temporal summation testing. Three months postoperatively, 38 participants completed the 12-item International Hip Outcome Tool (iHOT-12) and reported their overall symptomatic improvement (0% to 100%, with 100% being normal). Participants were categorized on the presence ( Numeric Pain Rating Scale; NPRS   2) or absence (  NPRS < 2) of temporal summation. A Mann-Whitney U test was used to determine the difference in improvement between groups (temporal summation: temporal summation (TS), no temporal summation (NTS), and a linear regression was used to explore predictors of improvement.

Results: 23 (45.1%) of 51 participants displayed preoperative temporal summation. In participants with postoperative data, those with temporal summation reported less improvement than those without (TS: 62.8%   29.7%; NTS: 82.7%   13.9%; p = 0.01; Cohen's d = -0.86). Temporal summation (Beta = -0.48; 95% CI -36.6, -8.7) and mental health disorder (Beta = -0.30; 95% CI -28.0, -0.48) predicted 28.1% of the variance in postoperative improvement (p = 0.002).

Conclusion: The presence of preoperative temporal summation is common and related to worse postoperative recovery after hip arthroscopy for FAIS.