Body Habitus Impact on Success of Cryoneurolysis for Postoperative Total Knee Arthroplasty Pain Control: A Retrospective Cohort Study

BACKGROUND: Cryoneurolysis utilizes temperatures below −20°C for nonpermanent analgesia to control pain in total knee arthroplasty (TKA). There is concern that body habitus could limit pain control because of accuracy of cryoneurolysis to subcutaneous nerves. This study aimed to determine the relationship between body habitus and effectiveness of cryoneurolysis on postoperative pain control. METHODS: A retrospective chart review was performed on patients undergoing cryoneurolysis before primary TKA from 2017 to 2019. Included were 114 patients (58 control group and 56 treatment group). Cryoneurolysis patients were divided into 3 groups (small, medium, and large) based on the soft tissue to femoral diaphysis ratio of 7 cm proximal to superior pole of the patella. Postoperative outcome measures were morphine equivalents, numerical rating score for pain, range of motion, and Knee Injury and Osteoarthritis Outcome Score Joint Replacement. RESULTS: The small cryoneurolysis group showed decreased opioid consumption at the 2, 6, and 12 weeks compared with control group, with morphine equivalents significantly decreased at 2 weeks for small compared with medium groups (54.3 vs 142.9, P = .0097). Numerical rating score for pain decreased significantly between small and medium groups (3.4 vs 4.0, P = .012) and between medium and large groups (4.0 vs 2.4, P = .012). Range of motion increased at 12 weeks for small group compared with medium group (118 vs 112, P = .042). There were no differences in any outcome measure between small and large groups. CONCLUSIONS: Body habitus does not appear to affect efficacy of cryoneurolysis in controlling postoperative pain following TKA. Cryoneurolysis remains a useful tool for multimodal pain management.