Background Lumbar spondylolysis is very frequency disorders of young athletes, particularly those involved in baseball, football, weight-lifting, and track & field. The rate of occurrence may be greater in Japanese subjects, in Eskimos, and in whites than in blacks. The fifth or fourth lumbar vertebra in the lower portion of the spine is affected most commonly. Although there are stress fractures of the pars interarticularis, the etiology of spondylolysis is still not clear¹. Hamstring tightness is commonly found in this symptomatic patient, but there are a few reports referring the relationship spondylolysis and tight hamstrings. In this report we show the novel dynamic X-ray examination of the lumbar spine. We have investigated mechanical motion of the lumbar vertebra in the teenager athletes suffering from back pain.

Objectives The aim of this study was to evaluate lumbar spinal alignment of young athletes, especially spondylolysis patients radiographically under straight leg raising (SLR) test.

Methods Thirty one patients with spondylolysis (no spondylolisthesis) and 32 normal asymptomatic subjects were evaluated (total 63 cases; f 25, m 38, the average was 14 years old). First, we examined patient’s dominant leg and evaluated bilateral SLR tightness (excellent, good, moderate, poor). We judged both excellent and good tightness (–), and moderate and poor tightness (+). We chose the one side leg more tight for X-P test. Six plain X-P were taken for each patient. Three dynamic radiographs of lumbar spine were originally taken during SLR posture in both lateral and A-P view. That is, the patients were lied for supine position at no SLR (0°), active SLR (40°-80° for tightness (–), 90°for tightness (+)), and passive SLR (over 90° for tightness (–), about 90° for tightness (+)). The segmental angulations at the level L1/2, L1/3, L1/4, L1/5, L1/S1 were measured with Cobb angle. We investigated relationship between lumbar ROM changes with spondylolysis or tight hamstring subjects by using statistically χ² test.

Results 1. 22 cases of spondylolysis patients were tightness (+). For example we found the SLR of the right leg changed the lumbar spinal alignment into left convex with vertebral rotation in A-P view, and into kyphosis in lateral view.

2. Results of spondylolysis patients; The Cobb angle (L1/5) were mean 17° at SLR 90° in A-P view. The Cobb angle (L1/5) were decreased to mean 30° kyphosis in lateral view with more instability at L4/5 level.

3. Tight hamstring made lumbar spine kyphoscoliosis more strongly. In female, the changes were no symmetry.

Conclusions This is the first radiographic report referring the chain of motion between leg and lumbar spine. We selected SLR test for supposing the kick position. During SLR motion, the athlete with tight hamstrings show lumbar scoliosis with opposite side convex with vertebral rotation, and decrease lumbar lordosis especially segmental angulations at L4/5 is maximum. We call these changes of lumbar alignment “Force of traction with torsion in the posterior of lumbar spine”. We speculate that tight hamstrings may not secondary changes of spondylolysis, but it is one of causes of spondylolysis.

1. Sairyo K, Am J Sports Med, 38, 2010

Disclosure of Interest None Declared