Associations among pain catastrophizing, muscle strength, and physical performance after total knee and hip arthroplasty.

AIM: To investigate whether reductions in pain catastrophizing associated with physical performance in the early period after total knee arthroplasty (TKA) or total hip arthroplasty (THA).

METHODS: The study group of 46 participants underwent TKA or THA. The participants were evaluated within 7 d before the operation and at 14 d afterwards. Physical performance was measured by the Timed Up and Go (TUG) test, and 10-m gait time was measured at comfortable and maximum speeds. They rated their knee or hip pain using a visual analog scale (VAS) for daily life activities. Psychological characteristics were measured by the Pain Catastrophizing Scale (PCS). Physical characteristics were measured by isometric muscle strength of knee extensors and hip abductors on the operated side. The variables of percent changes between pre- and post-operation were calculated by dividing post-operation score by pre-operation score.

RESULTS: Postoperative VAS and PCS were better than preoperative for both TKA and THA. Postoperative physical performance and muscle strength were poorer than preoperative for both TKA and THA. The percent change in physical performance showed no correlation with preoperative variables. In TKA patients, the percent change of PCS showed correlation with percent change of TUG ( P = 0.016), 10-m gait time at comfortable speeds ( P = 0.003), and 10-m gait time at maximum speeds ( P = 0.042). The percent change of muscle strength showed partial correlation with physical performances. The percent change of VAS showed no correlation with physical performances. On the other hand, in THA patients, the percent change of hip abductor strength showed correlation with percent change of TUG ( P = 0.047), 10-m gait time at comfortable speeds ( P = 0.001), and 10-m gait time at maximum speeds ( P = 0.021). The percent change of knee extensor strength showed partial correlation with physical performances. The percent change of VAS and PCS showed no correlation with physical performances.

CONCLUSION: Changes in pain catastrophizing significantly associated with changes in physical performance in the early period after TKA. It contributes to future postoperative rehabilitation of arthroplasty.