MARCH/APRIL 2016 |฀Volume฀39฀•฀Number฀2 n Review Article abstract Paraspinal Muscle Atrophy After Lumbar Spine Surgery SINA POURTAHERI, MD; KIMONA ISSA, MD; ELIZABETH LORD, MD; REMI AJIBOYE, MD; AUSTIN DRYSCH; KI HWANG, MD; MICHAEL FALOON, MD; KUMAR SINHA, MD; ARASH EMAMI, MD P araspinal muscles are commonly affected during spine surgery. 1 This is partly due to retraction or dissec- tion techniques, which can potentially re- sult in iatrogenic denervation, ischemic or thermal damage, and progression to even- tual atrophy of the paraspinal muscles. 1-4 This may lead to pain and instability and contribute to poor clinical outcomes, in- creased morbidity, and surgical failures requiring revision surgery, which is an additional challenge for the treating sur- geon. Furthermore, disuse of the paraspi- nal muscles as a consequence of a lumbar fusion may also contribute to postopera- tive paraspinal muscle atrophy (PMA). 1-3,5 Some authors have suggested that be- cause paraspinal muscles are supplied by the posterior rami of the spinal nerves and do not have intersegmental innerva- tion, injury to these nerves potentially damages all the muscle bundles they in- nervate. 6 Several studies have introduced surgical modifications to attempt to pre- serve the posterior rami and minimize potential postoperative PMA. 4,5,7-12 These include modifying incision length, ex- posure techniques, retraction, and screw trajectory and using lower electrocautery settings. 7-12 However, to the current au- Paraspinal muscles are commonly affected during spine surgery. The pur- pose of this study was to assess the potential factors that contribute to para- spinal muscle atrophy (PMA) after lumbar spine surgery. A comprehensive review of the available English literature, including relevant abstracts and references of articles selected for review, was conducted to identify studies that reported PMA after spinal surgery. The amount of postoperative PMA was evaluated in (1) lumbar fusion vs nonfusion procedures; (2) posterior lumbar fusion vs anterior lumbar fusion; and (3) minimally invasive (MIS) posterior lumbar decompression and/or fusion vs non-MIS equivalent pro- cedures. In total, 12 studies that included 529 patients (262 men and 267 women) were reviewed. Of these, 365 patients had lumbar fusions and 164 had lumbar decompressions. There was a significantly higher mean post- operative volumetric PMA with fusion vs nonfusion procedures (P=.0001), with posterior fusion vs anterior fusion (P=.0001), and with conventional fusions vs MIS fusions (P=.001). There was no significant difference in mean volumetric lumbar PMA with MIS decompression vs non-MIS decompres- sion (P=.56). There was significantly higher postoperative PMA with lumbar spine fusions, posterior procedures, and non-MIS fusions. [Orthopedics. 2016; 39(2):e209-e214.] The authors are from UCLA/Orthopaedic In- stitute for Children (SP, EL, RA, AD), Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Santa Monica, California; and the School of Health and Medical Sciences (KI, KH, MF, KS, AE), Seton Hall University, South Orange Village, and the Department of Or- thopaedic Surgery, Saint Joseph Regional Medi- cal Center, Paterson, New Jersey. Dr Pourtaheri, Dr Issa, Dr Lord, Dr Ajiboye, Mr Drysch, Dr Faloon, and Dr Sinha have no relevant financial relationships to disclose. Dr Hwang is on the speaker’s bureau of DePuy. Dr Emami is a paid consultant for and is on the speaker’s bureau of DePuy. Correspondence should be addressed to: Sina Pourtaheri, MD, UCLA/Orthopaedic Institute for Children, Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, 1250 16th St, Ste 3145B, Santa Monica, CA 90404 (spourtah@gmail.com). Received: August 1, 2014; Accepted: Febru- ary 4, 2015. doi: 10.3928/01477447-20160129-07 e209