Experimental Study Of The Impact Of Different Lumbar Posterior Approaches On Multifidus Muscle

Objective:To assess the effect of different lumbar posterior surgical approaches and reconstructive methods of spinous process on multifidus muscle occurring after lumbar surgery..Methods:Forty adult goats were used as experimental animals. The animals were 38～40Kg. They were randomly divided into four groups (10 animals each group). Group A underwent spinous process-splitting procedure to expose the lamina. In group B, bilateral multifidus muscles were stripped and spinous process was excised. In group C, unilateral multifidus muscle (group C1) was stripped; the spinous process was cut at the bottom and exposed the contralateral lamina. The bilateral multifidus muscles were stripped in group D to mimic laminoplasty procedure. The surgical level (Lumbar 6), length of incision (4cm), detachment extent of multifidus muscles, the retracting distance and time (40min) of muscles were same in all groups. The atrophy rate of cross-sectional area (CSA) of multifidus muscle, MRI and histological changes of the muscle tissue were evaluated 10 months after surgery. A normal multifidus muscle taken from a health goat at L6 level and the preoperative data of MRI in experiment animals were used as control group (group E).Results:All experiment animals had muscle atrophy in different degree. MRI and histological scores of multifidus muscles of group A, B, C, D were significantly decreased than those of group E (P<0.05). The postoperative MRI and histological scores of group A and C2 were highest and the atrophy rate was lowest, while animals of group B had highest atrophy rate and lowest MRI and histological scores among all experimental groups (P<0.05). The data of group A and C1 had no difference (P>0.05). There was no difference between group C1 and D (P>0.05). The groups (group A and C2) which did not trip muscles from spinous process acquired better results than groups (group C1 and D) which stripped muscles (P<0.05). The groups (group C1, D) which reconstructed spinous process after detachment of muscles acquired better results than group B (P<0.05).Conclusion:Multifidus muscle can be effectively protected by reducing extent of muscle detachment and reconstructing posterior bone-ligament complex. Spinous process-splitting procedure is an effective method to avoid postoperative muscle atrophy.