Bone mineral density (BMD) may be an important factor affecting the clinical outcomes after total knee arthroplasty (TKA). However, further information regarding BMD in postoperative pain relief is not present yet. This study aims to gain further insight into the predictive significance of BMD in postoperative pain relief in knee osteoarthritis (KOA) patients after TKA.
156 KOA patients treated by TKA were included in this study. Visual analogue scale (VAS) was used to measure the pain intensity in patients within one year after TKA. The patients were divided into good pain relief group (the improvement of VAS ≥ 3) and poor pain relief group (the improvement of VAS < 3). BMD and other clinical characteristics were also collected. Logistic regression analysis and receiver operating characteristic curve (ROC curve) were used to evaluate the predictive significance of BMD. Subgroup analysis was used to compare the difference of postoperative pain between High BMD group and Low BMD group extra.
34 (21.8%) patients had poor pain relief after TKA. Logistic regression analysis indicated that age, BMD, preoperative hospital for special surgery (HSS) scores, preoperative VAS score and postoperative posterior slope angles (PSA) were the risk factors of poor pain relief (P < 0.05). Using BMD as a predictor, the optimum cut-off value of poor pain relief was T-level = -3.0 SD in the ROC curve, where sensitivity and specificity were 73.5% and 83.7%, respectively. Based on this cut-off value, obvious pain relief was observed in the High BMD group compared with Low BMD group from the 6th month after TKA in the subgroup analysis (P < 0.05).
BMD is an effective predictor for postoperative pain relief in KOA patients after TKA, and the poor pain relief should be fully considered especially when BMD T-level ≤ -3.0 SD.