The purpose of this study is to investigate whether preoperative TSP using QuantiPain®︎ can predict postoperative pain after total knee arthroplasty (TKA).
Eighty-six patients (age 75±7 years, 63 women, Kellgren-Lawrence gradeⅣ) who were underwent primary TKA at our hospital and could be followed up for one year after surgery were recruited. Preoperative TSP was evaluated by 10 consecutive stimuli (1 second interval between the stimulus) by using pinprick on the operation side of tibialis anterior muscle (5 cm distal to the tibial tuberosity). The TSP effect was calculated as the difference in the pain visual analogue scale (VAS) between the first and the last stimuli. The VAS was anchored with “no pain” and “worst pain imaginable” at 0 mm and 100 mm, respectively. The TSP results were performed Z-transformation based on the standard values for healthy adults (N = 300, previously investigated) and the patients were divided into an abnormal group (Z-score ≥ 1.96) and a normal group. Motion pain VAS in each group was investigated at before surgery, 3, 6 months and 1 year after surgery. For statistical analysis, motion pain VAS was compared between the two groups at all time points.
Twenty-five (29%) patients showed Abnormal TSP before surgery. Before surgery the abnormal group showed significantly stronger motion pain compared to the normal group (abnormal group: 63.2±21.3mm, normal group: 41.9±20.9mm, P0.05). After surgery, the abnormal group had more severe motion pain compared to the normal group, respectively (abnormal group: 28.2±21.0mm, normal group: 10.1±12.2mm at 3months; abnormal group: 23.6±19.8mm, normal group: 10.7±13.1mm at 6months; abnormal group: 18.2±14.2mm, normal group: 5.1±11.2mm at 1 year; P0.05).
Abnormal TSP group showed stronger motion pain at all time points. It has been reported that the increasing TSP in patients with end-stage OA is caused by local nociceptive input, and that reduction of this input by joint replacement improves the condition. However, the result of this study suggests that patients with abnormal preoperative TSP may not gain much improvement in pain after surgery. This indicates the need to focus on preoperative interventions such as rehabilitation and patient education aimed at improving TSP, as well as postoperative pain management.
QuantiPain®︎ can be measured quickly and anywhere, and is thought to be clinically useful as a preoperative screening test.
temporal summation of pain
postoperative pain
