PREDICTORS AND TRAJECTORIES OF CHRONIC POST-OPERATIVE PAIN FOLLOWING HIP PRESERVATION SURGERY

Purpose Factors contributing to chronic postoperative pain (CPOP) are poorly defined in young people and developmental considerations are poorly understood. With over 5 million children undergoing surgery yearly and 25% of adults referred to chronic pain clinics identifying surgery as the antecedent, there is a need to elucidate factors that contribute to CPOP in young people. The present study includes patients undergoing hip preservation surgery at a children's hospital. Methods The HOOS and the SF-12 Health Survey were administered to 614 patients prior to surgery with 422 patients completing follow-up data (6-months, 1-year, and 2-years post-surgery). Examining baseline characteristics for those who completed follow-up versus those who did not, the only significant difference was that patients with more than one surgery were less likely to complete follow-up measures. Pain, quality of life, and functioning across time were examined using SAS PROC TRAJ procedure, a mixture model that estimates a regression model for each discrete group within the population. Longitudinal pain trajectories were empirically grouped. Baseline preoperative characteristics of age, gender, preoperative pain, quality of life, functioning, and mental health that could potentially distinguish trajectory groups were examined. Results A three trajectory model (low pain, pain improvement, and high pain) emerged indicating three different treatment responders. Pain trajectory groups did not differ significantly on gender, presurgical age, BMI, prior hip surgery, surgical type, joint congruence, or Tonnis grade. The pain trajectory groups differed significantly from each other on presurgical pain, pain chronicity, quality of life, and functioning. Those in the high pain group and pain improvement group endorsed having presurgical depression at significantly higher rates and lower presurgical quality of life compared to those in the low pain group (p<.01). Similarly, those in the high pain group reported significantly worse functioning prior to surgery compared to the pain improvement group (p<.0001) and those in the low pain group (p<.0001). Conclusions Chronic pain is a common problem and surgery can be a trigger. There may be a subset of hip preservation surgery patients who are predisposed to chronic pain independent of hip health. The results demonstrate the need for preoperative screening prior to hip preservation surgery. A prospective, interventional study to identify patients at risk for a poor pain trajectory is underway. Significance This is the largest study to date to examine longitudinal pain, quality of life, and functioning trajectories for adolescent and young adults undergoing hip preservation surgery. Chronic pain is a serious public health concern, with the United States spending $19 billion annually on pain-related disability. Identifying predictors of poor long-term outcomes in adolescents and young adult samples with postoperative pain may prevent the development of chronic pain into adulthood as well as inform presurgical preparation and postsurgical care.