The Effect of Muscle Quality on Outcomes after Microdiscectomy

Abstract

ObjectivesTo investigate the relationship between muscle quality and (1) patient-reported outcomes and (2) surgical outcomes after lumbar microdiscectomy surgery. MethodsAdult patients (>18 years) who underwent lumbar microdiscectomy from 2014-2021 at a single academic institution were identified. Outcomes were collected during the preoperative, three-month, six-month, and one-year postoperative periods. Those included were the Oswestry Disability Index (ODI), Visual Analog Scale Back and Leg (VAS-Back and VAS-Leg, respectively), and the mental and physical component of the short-form 12 survey (MCS and PCS). Muscle quality was determined by two systems: the normalized total psoas area (NTPA) and a paralumbar-based grading system. Surgical outcomes including 90-day surgical readmissions and 1-year reoperations were also collected. ResultsOf the 218 patients identified, 150 had good paralumbar muscle quality and 165 had good psoas muscle quality. Bivariant analysis demonstrated no difference between groups regarding surgical outcomes (p>0.05). Multivariable analysis demonstrated that better paralumbar muscle quality was not associated with any consistent changes in patient reported outcomes. Higher NTPA was associated with improved PCS at six months (est. = 6.703, [95% CI: 0.759 – 12.646], p=0.030) and twelve months (est. = 6.625, [95% CI: 0.845 – 12.405], p=0.027). There was no association between muscle quality and surgical readmissions or reoperations. ConclusionsOur analysis demonstrated that higher psoas muscle quality was associated with greater physical improvement postoperatively. Muscle quality did not affect surgical readmissions or reoperations. Additional studies are needed for further assessment of the implications of muscle quality on postoperative outcomes.