Thigh pain after total knee arthroplasty: Analysis of risk factors

IntroductionThigh pain may sometimes occur following total knee arthroplasty (TKA). The existence of thigh pain can interfere with postoperative rehabilitation and result in an unpleasant postoperative period. Our aim is to identify the risk factors of post-TKA thigh pain. Although the application of a pneumatic tourniquet is common while performing a TKA, it seems to play a role in the development of post-TKA thigh pain. In addition to the use of a tourniquet, some patient factors may also be associated with the occurrence of thigh pain after TKA. Therefore, we hypothesized that some factors correlated to post-TKA thigh pain exist.Materials and methodsDuring 2011–2012, we conducted a prospective cohort study enrolling 347 patients (with 411 cases of primary TKA) in Taipei Veterans General Hospital. There were 283 cases of unilateral and 64 cases of bilateral knee arthroplasty, respectively. All surgeries were performed by a single surgeon. Thigh pain was measured according to the patients' response to the “squeeze test” on the next day after surgery, performed by a single technician. Thigh pain after surgery developed in 33 out of 411 cases of primary TKA. We analyzed the correlation between thigh pain and several possible risk factors, including age, gender, body mass index (BMI), tourniquet time, blood pressure, tourniquet pressure, thigh circumference, and use of patient-controlled analgesia (PCA), using a generalized estimating equation, with SPSS software version 19.0 (SPSS Inc., Chicago, IL, USA).ResultsThe study consisted of 77 male (22%) and 270 female (78%) patients. The mean age of the patients was 72.2 years (range, 29–89 years). The mean tourniquet time was 35.3 minutes and mean cuff pressure was 268.8 mmHg. Higher diastolic blood pressure and higher tourniquet pressure correlated to thigh pain, which achieved statistical significance. Age, gender, BMI, PCA use, and tourniquet time were found to have no significant influences on the occurrence of thigh pain.DiscussionIn this study, higher diastolic blood pressure and higher tourniquet pressure were found to have a correlation with thigh pain. Tissue ischemia and reperfusion may explain this finding. Tourniquet time seemed irrelevant, the reason for which might be attributed to the short tourniquet time in our study. In conclusion, factors that influence post-TKA thigh pain exist.