Relationships of cross-sectional area of the thigh muscles before or after total knee arthroplasty with postoperative pain or patient satisfaction: A retrospective, exploratory study

BACKGROUND: It has been suggested that lower limb strength related to persistent postsurgical pain. The aim of the present study was to investigate the relationships of pre-operative or postoperative cross-sectional area (CSA) of the thigh muscles with knee pain or patient satisfaction after total knee arthroplasty (TKA). METHODS: Twenty patients who had undergone TKA (3 men and 17 women; mean age 75.2 ± 8.7 years) were included. CSAs of the thigh muscle (THIGH) and quadriceps muscle (QUAD) were retrospectively measured at the CT slice 10-cm superior to the quadriceps tendon insertion at the proximal pole of the patella. THIGH CSA and QUAD CSA to body weight ratios (mm(2)/kg), THIGH/W and QUAD/W ratios, respectively, were calculated. Knee pain and patient satisfaction postoperatively were also quantified by patient-reported measurements based on the 2011 Knee Society Score (KSS). The correlations between the THIGH/W and QUAD/W ratios and the KSS were evaluated using Spearman's rank correlation coefficient. RESULTS: The preoperative THIGH/W ratio was positively correlated with KSS-pain, (r = 0.58, p < 0.05). The preoperative QUAD/W ratio was positively correlated with KSS-pain (r = 0.52, p < 0.05) and KSS-satisfaction (r = 0.44, p < 0.05). The postoperative THIGH/W ratio was positively correlated with KSS-pain (r = 0.45, p < 0.05). The postoperative QUAD/W ratio was positively correlated with KSS-pain (r = 0.49, p < 0.05) and KSS-satisfaction (r = 0.48, p < 0.05). CONCLUSION: There were significant correlations between quadriceps or thigh muscle CSA and pain or patient satisfaction after TKA. This research may help relieve pain and increase patient satisfaction after TKA in the future.