Biochemical measurement of muscle injury created by lumbar surgery

1. To determine whether lumbar disc surgery (LS) provides a sufficiently detectable rise in serum creatine kinase (CK) concentration to serve as a model to study biochemical measurement of muscle injury, and 2. To use the model to examine the consistency of the time course of CK concentration changes.

The study used a repeated measures design. Six women and six men scheduled for LS were recruited. Blood samples were taken in the pre-operative waiting areas, immediately after surgery, at 6 hour intervals until discharge, and at 2, 4, and 6 to 7 days following surgery. Total serum CK was quantified using the Roche Modular to detect enzyme concentration.

Following LS, mean Total CK increased from a baseline 50 U/L (SD = 53) to a peak 114 U/L (SD = 32) in women (P < 0.001) and from 183 U/L (SD = 69) to a peak 454 U/L (SD = 173) in men (P < 0.05). Baseline to peak changes in CK exceeded subjects' own baseline fluctuations in all 6 women and all 6 men, and amounted to a mean 6 fold (SD = 4) increase in women and 16 fold (SD = 31) increase in men. While CK concentrations returned to baseline over the observation period in all subjects, time to peak ranged between 9 to 47 hours.

The LS model produced a consistently detectable CK response in both genders. Time to peak is variable indicating a need for multiple serial measures to capture this biochemical injury response.