General Session: MIS-1
Presented by: L. Pimenta - View Audio/Video Presentation (Members Only)
L. Pimenta(1,2), R. Aquaroli(1), E. Camacho(1), R. Amaral(1), L. Oliveira(1), E. Coutinho(1), L. Marchi(1)
(1) Instituto de Patologia da Coluna, Sao Paulo, Brazil
(2) UCSD, Neurosurgery, San Diego, CA, United States
Background: Minimally invasive lateral interbody fusion (LLIF) through retroperitoneal transpsoas approach to has gained many of adepts in the last decade. The technique requires blunt dissection through the psoas muscle to reach the lumbar spine. It has been shown that it can cause some collateral effects related to the psoas muscle and the lumbar plexus which runs through. Thigh pain, numbness, paresthesias, and weakness are some examples of plexopaties and the loss of contractile power of the psoas fibers stands for an iatrogenic inhibition. This work evaluated the motor deficit following the passage through the psoas muscle in the LLIF approach.
Methods: We conducted a prospective, non-randomized, controlled, single center study. 50 patients with mean age 62.4 years were enrolled. All subjects underwent to a lateral retroperitoneal transpsoas approach for lumbar interbody fusion using EMG guidance. One to three lumbar levels were accessed in these cases (mean levels 1.4; 70% one-level; 72% included L4L5). Isometric hip flexion strength at sitting position was determined bilaterally with a hand-held dynamometer. The mean of 3 peak force (N) measurements was calculated. Standardized isometric strength tests were performed preop and postop on day 10, 6 weeks, and 3 months. Isilateral and contralteral sides to the surgical access were compared.
Results: Hip flexion was diminished (p< 0.001) at the early postop but at 6 weeks had reached preop values (p< 0.32). Mean values for preop, 10d, 6w, and 3m from hip flexion measure were: (Ipsilateral) 13.4N; 9.6N; 14.4N; 14.0N; (Contralateral) 12.9N; 13.4N; 15.1N; 14.4N. Neither the level nor the number of levels treated had clear association with thigh symptoms, but weaker the hip flexion was more tight symptoms were found.
Conclusions: Postoperative period of transpsoas access present hip flexion weakness at one week after surgery. However, we have observed that this occurrence is transient. EMG use is still imperative in transpsoas access and larger casuistic studies are required to complete the understanding of those effects, collateral damages and complications. In addition, patient education should be widely applied to alert regarding the hip flexion weakness in order to prevent falls, cage subsidence and other complications.
Hip flexion strength