Relationship of the functional recovery after hip arthroplasty to the neuroendocrine and inflammatory responses.

We studied the relationship between the neuroendocrine and inflammatory responses to hip arthroplasty and functional recovery in 102 patients undergoing elective arthroplasty for osteoarthritis. Blood samples were collected for up to 7 days after surgery and analysed for concentrations of norepinephrine, epinephrine, cortisol, interleukin-6 and C-reactive protein. The primary outcome measures were milestones in hospital, times to walk 10 and 25 m, pain on discharge from hospital, and function 1 and 6 months after surgery. Walking distances in hospital were significantly delayed in patients with greater interleukin 6 and C-reactive protein concentrations, but few neuroendocrine measures had significant correlations with functional recovery in hospital. Multivariate analysis showed that the interleukin 6 concentration on day 1 was the unique predictor of time to walk 10 and 25 m, and that the day 2 concentration of C-reactive protein was the unique predictor of pain on discharge from hospital. No significant correlations were found between the inflammatory and neuroendocrine variables and recovery at 1 and 6 months. We conclude that the inflammatory response affects immediate functional recovery after hip arthroplasty.