Microscopic Lumbar Multifidus Muscle Changes after Lumbar Disc Herniation are Characterized by Muscle Fibre Atrophy in the Acute, but not in the Chronic Patient Population

Abstract

Objectives Therefore, the objectives of this study were to: 1) investigate possible changes in MM fibre type proportion and CSA between the affected and non-affected sides in people suffering from LDH vs. healthy controls, 2) investigate the impact of duration of symptoms on microscopic muscle alterations. Measurements Multifidus muscle biopsy samples were taken during minimally invasive surgery for muscle fibre analysis. Myosine heavy chain (MHC) isoforms were investigated using immunohistochemistry. Results Muscle fibre atrophy for type I (p<0.0001), IIA (p=0.01) and IIAX muscle fibres (p= 0.0088) was only observed in the acute period after LDH, with a significant segmental decrease in CSA on the affected side. No significant differences in CSA were seen within the chronic population group. Additionally, no significant differences in fibre proportion, nor relative CSA were observed in either groups. Conclusion These data provide clear evidence of ipsilateral segmental MM fibre atrophy in the acute, but not chronic time course after LDH. Rehabilitation programs should therefore implement specific treatment principles and goals within each time course after LDH in order to optimize treatment outcomes.