Validity of creatine kinase as an indicator of muscle injury in spine surgery and its relation with postoperative pain.

PURPOSE: To confirm the validity of postoperative creatine kinase (CK) values as an indicator of muscle lesion, assess the relationship of CK with variables indicating surgical invasiveness and investigate an association between CK values and excessive postoperative pain.

MATERIAL AND METHODS: The study included 96 patients (mean age 62.8 years) who underwent instrumented spine fusion for degenerative lumbosacral disease. Serum CK concentration was determined on the first postoperative day. All patients received intravenous paracetamol and metamizole, and in cases of intense pain, rescue analgesia with iv meperidine. Patients were categorized according to whether or not they required rescue analgesia. Data on the number of levels fused, the duration of surgery, and operative bleeding were recorded in each patient.

RESULTS: CK values were higher in men and in younger patients. Significant correlations were found between CK and the number of fused levels and duration of surgery. Only 17.7% of patients required rescue analgesia. CK levels did not significantly differ between patients who did not need rescue analgesia (1135 IU/L) and those who did (1421.5 IU/L).

CONCLUSIONS: Serum CK concentration is a valid marker of surgical muscle injury and is affected by the age and sex. Factors such as the magnitude and duration of surgery show a relationship with postoperative CK values. The incidence of severe postoperative pain is not significantly related to CK level.