Study design: The histologic and histochemical changes in back muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery.
Objectives: The results were correlated to provide the evidences of histologic changes of back muscle after posterior lumbar surgery.
Summary of background data: Back muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes.
Methods: Back muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, muscle samples were obtained before muscle retraction. Samples were evaluated by histologic and histochemical methods.
Results: Abnormal findings were slight in virgin surgery cases. Early back muscle injury tended to depend on operation time and [P][T] products. Late back muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation.
Conclusions: Histologic damages of back muscle due to previous surgical intervention were long-lasting. To avoid permanent muscle injury, the retraction time and pressure should be shortened or the pressure on the back muscle should be monitored during posterior surgery.