Quadratus Lumborum Asymmetry and L4 Pars Injury in Fast Bowlers

Engstrom, C. M., D. G Walker, V. Kippers, and A. J. H. Mehnert. Quadrants Lumborum Asymmetry and L4 Pars Injury in Fast Bowlers: A Prospective MR Study. Med. Sci. Sports Exerc., Vol. 39, No. 6, pp. 910-917, 2007. Purpose: This prospective study examined the association between quadratus lumborum (QL) asymmetry and the development of symptomatic pars interarticularis lesions in the lumbar spine of adolescent cricket fast bowlers. Methods: Annual magnetic resonance imaging was used to measure QL volume asymmetry and for identifying pars lesions of the lumbar vertebrae in fast bowlers (N = 5 1) and a control group of swimmers (N = 18). Manual segmentation of axial images spanning the lumbar spine was performed to calculate percent QL asymmetry relative to the bowling- or throwing- (swimmers) arm side. Asymmetry above 100% indicated a larger QL volume on the bowling- (throwing) arm side. Results: The mean QL asymmetry in bowlers of 110.5% (SD = 12.1%) was significantly different from the 96.6% (SD = 5.0%) asymmetry in swimmers (t = 6.75, P