Unilateral spondylolysis

Spondylolysis and End Plate Arthrosis at L5-S1: A Cadaveric Study

This study examined the effect of bilateral and unilateral L5 pars defects on the degree of disk degeneration at the L5-S1 level in cadaveric specimens. An observational study was performed of 690 cadaveric specimens selected at random. These specimens represent individuals who died between 1893 and 1938. The study included 558 male and 132 female cadavers. Of the 120 specimens with L5 spondylolysis, 95 cases were bilateral and 25 were unilateral. The remaining 544 specimens were used as the control cohort. Degenerative disk disease was measured by the classification of Eubanks et al. According to this classification, degenerative disk disease was graded from no arthrosis (grade 0) to complete ankylosis (grade IV). Linear regression analysis corrected for age, sex, and race showed that subjects with bilateral spondylolysis at L5 had a statistically significant increase in the amount of disk degeneration (P=.02) compared with those with unilateral lesions. Student's t tests showed significant differences (P<.001 and P=.002, respectively) in the amount of degeneration seen with both bilateral and unilateral spondylolysis above what would be predicted in the normal control population. A positive correlation was found between the number of pars defects at L5 and the degree of disk degeneration at L5-S1. These results support the idea that individuals with spondylolysis at these levels may be at increased risk for development of low back pain and reduced quality of life. [Orthopedics. 2017; 40(1):e59-e64.].

Symptomatic Unilateral Spondylolysis Associated With Nonspondylolytic Lateral Clefts in Adults: Review of an Infrequently Reported Pathology

Nonspondylolytic lateral clefts of the lumbar neural arch (laminolysis and pediculolysis) are rare pathologies that usually occur consequent to repetitive stress injuries in patients with unilateral spondylolysis. These lesions are different from the usual bilateral spondylolytic defects, and their management depends upon the chronicity and the type of bony defect. We hereby discuss the verdict of current literature on underlying pathomechanics and ideal management guidelines of these rare lesions.

Clinical outcome of symptomatic unilateral stress injuries of the lumbar pars interarticularis

STUDY DESIGN

A prospective case-series study.

OBJECTIVE

To evaluate the results of nonoperative and operative treatment of symptomatic unilateral lumbar pars stress injuries or spondylolysis.

SUMMARY OF BACKGROUND DATA

Most patients become asymptomatic following nonoperative treatment for unilateral lumbar pars stress injuries or spondylolysis. Surgery, however, is indicated when symptoms persist beyond a reasonable time affecting the quality of life in young patients, particularly the athletic population.

METHODS

We treated 42 patients (31 male, 11 female) with unilateral lumbar pars stress injuries or spondylolysis. Thirty-two patients were actively involved in sports at various levels. Patients with a positive stress reaction on single photon emission computerized tomography imaging underwent a strict protocol of activity restriction, bracing, and physical therapy for 6 months. At the end of 6 months, patients who remained symptomatic underwent a computed tomography (CT) scan to confirm the persistence of a spondylolysis. Eight patients subsequently underwent a direct repair of the defect using the modified Buck's Technique. Baseline Oswestry Disability Index (ODI) and Short-Form-36 (SF-36) scores were compared with 2-year ODI and SF-36 scores for all patients.

RESULTS

Eight of nine fast bowlers in cricket were right-handed. The spondylolytic defect appeared on the left side of their lumbar spine. In the nonoperated group, the mean pretreatment ODI was 36 (SD = 10.5), improving to 6.2 (SD = 8.2) at 2 years. In SF-36 scores, the mean score for physical component of health (PCS) improved from 30.7 (SD = 3.2) to 53.5 (SD = 6.5) (P < 0.001), and the mean score for the mental component of health (MCS) improved from 39 (SD = 4.1) and 56.5 (SD = 3.9) (P < 0.001) at 2 years. Twenty of 32 patients resumed their sporting career within 6 months of onset of treatment, and a further 4 of 32 patients returned to sports within 1 year. The 8 patients who remained symptomatic at 6 months underwent a unilateral modified Buck's repair. The most common level of repair was L5 (n = 5). One patient with spina bifida and a right-sided L5 pars defect remained symptomatic following direct repair. The mean preoperative ODI was 39.4 (SD = 3.6), improving to 6.4 (SD = 5.2) at the latest follow-up. The mean score of PCS (SF-36) improved from 29.6 (SD = 4.4) to 49.2 (SD = 6.2) (P < 0.001), and the mean score of MCS (SF-36) improved from 38.7 (SD = 1.9) to 54.5 (SD = 6.4) (P < 0.001).

CONCLUSIONS

The increased incidence of the unilateral lumbar pars stress injuries or frank defect on the contralateral side in a throwing sports, e.g., cricket (fast bowling), may be related to the hand dominance of the individual. Nonoperative treatment for patients with a unilateral lumbar pars stress injuries or spondylolysis resulted in a high rate of success, with 81% (34/42) of patients avoiding surgery. If symptoms persist beyond a reasonable period, i.e., 6 months, and reverse gantry CT scan confirms a nonhealing defect of the pars interarticularis, one may consider a unilateral direct repair of the defect with good functional outcome. Direct repair in patients with spina bifida at the same lumbar level as the unilateral defect may be complicated by nonunion.

Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population

The prevalence of spondylolysis and spondylolisthesis was studied in an adult skeletal series from a rural English medieval archaeological site. Attempts were made to evaluate the association of three aspects of lumbo-sacral skeletal morphology (pelvic incidence (a measure of the anterior inclination of the sacral table), lumbar transverse process width, and the presence of lumbo-sacral spina bifida occulta) with spondylolysis and spondylolisthesis. Results indicated a high prevalence of spondylolysis compared with a modern reference population, but few cases of spondylolisthesis were identified. Analysis of prevalence with respect to age suggests that in the study population, pars interarticularis defects generally formed late in the growth period or early in adult life. The study group showed a high mean pelvic incidence compared with modern Western Europeans, indicating a more steeply inclined sacral table, which may have elevated the risk of developing pars interarticularis defects. However, no statistically valid association could be demonstrated between the presence/absence of spondylolysis and pelvic incidence in the study material. There was no evidence for a link between lumbar transverse process index or lumbo-sacral spina bifida occulta and spondylolysis/spondylolisthesis. It is concluded that the potential role of lumbo-sacral morphology, as well as of activity regimes, should be considered when interpreting spondylolysis in paleopathological studies. If the frequency of spondylolysis is to some extent an indicator of past activity regimes, it may reflect lifestyle in younger individuals rather than in mature adults. Further work investigating the link between spondylolysis and lumbo-sacral morphological variables in premodern populations would be of value.

Athletes with unilateral spondylolysis are at risk of stress fracture at the contralateral pedicle and pars interarticularis: a clinical and biomechanical study

BACKGROUND

Unilateral spondylolysis is common in youths; its clinical and biomechanical features, especially effects on the contralateral side, are not fully understood.

HYPOTHESIS

Unilateral spondylolysis predisposes the contralateral side to stress fracture, especially in athletes actively engaged in sporting activities involving torsion of the trunk.

STUDY DESIGN

Case series and descriptive laboratory study.

METHODS

Thirteen athletes younger than age 20 with unilateral spondylolysis were included. The contralateral pedicle and pars of spondylolytic vertebrae were examined using computed tomography and magnetic resonance imaging. Using a finite element model of the intact ligamentous L3-S1 segment, stress distributions were analyzed in response to 400-N axial compression and 10.6-N.m moment in flexion, extension, lateral bending, and axial rotation. Unilateral spondylolysis was created in the model at L5. The stress results from the unilateral defect model were compared to the intact model predictions and correlated to the contralateral defects seen in patients.

RESULTS

Among 13 patients, there were 6 early-, 2 progressive-, and 5 terminal-stage defects. Three (23.1%) showed contralateral stress fracture. Among them, 2 belonged to the progressive-stage and 1 to the terminal-stage spondylolysis group. The remaining 4 patients in the terminal defect group showed stress reactions, such as sclerosis at the contralateral pedicle. In the finite element analysis model with an L5 left spondylolysis, the stresses at the contralateral and pars interarticularis were found to increase in all loading modes, with increases as high as 12.6-fold compared to the intact spine.

CONCLUSIONS

Unilateral spondylolysis could lead to stress fracture or sclerosis at the contralateral side due to an increase in stresses in the region.

CLINICAL RELEVANCE

Surgeons should be aware of possibility of contralateral stress fractures in cases in which patients, especially athletes engaged in active sports, show unilateral spondylolysis and persistent low back pain complaints.

The value of combining single photon emission computerised tomography and computerised tomography in the investigation of spondylolysis

The aim of this study was to assess the diagnostic value of combining single photon emission computerised tomography (SPECT) with reverse gantry computerised tomography (rg-CT) in the investigation of spondylolysis. Patient characteristics and imaging results in 118 patients, aged 8-44 years, with low back pain (LBP) were analysed. SPECT showed increased scintigraphic uptake in 80 patients, and spondylolysis was identified on rg-CT in 53. The Cohen Kappa ratio of 0.362 (95% CI: 0.198-0.526) suggests only fair agreement for the result of increased scintigraphic activity with the finding of spondylolysis on rg-CT. We conclude that these investigations give mutually exclusive information, which leads to four diagnostic categories. When there was increased scintigraphic activity on SPECT, 58.8% (95% CI: 48.0-69.5%) of patients had spondylolysis on rg-CT. With rest from provoking activities, these lesions may heal. We interpret the findings of increased scintigraphic activity, but no spondylolysis demonstrated on rg-CT as indicating a bone stress response. These also require rest from provoking activity to prevent a stress fracture developing. In this study, 84.2% (95% CI: 72.67-95.8%) of those patients without increased activity on SPECT had no spondylolysis identified on rg-CT. These patients may need further investigations such as magnetic resonance imaging (MRI) to diagnose pathology, which typically does not involve the posterior elements--but rest from sport may not be so important. There were five patients in our study, without increased scintigraphic activity, but in whom bilateral chronic-appearing (wide separation, smooth sclerotic bone margins) spondylolyses were identified at L5. These all were anticipated from previous plain radiographs or MRI. This group will almost certainly not heal, and if the spondylolyses are the cause of pain these vertebrae will need stabilisation by surgery if physiotherapy fails.

Asymmetrical spondylolysis

The objective of this study was to examine examples of spondylolysis in which the pattern of separation was clearly asymmetrical, in order to learn more about the process of bone separation that produces this condition. Although the primary focus was on unilateral complete separation, examples of asymmetry represented by incomplete separation and by complete bilateral separation where the separation sites are in different locations on the two sides were included. Two collections were used, one consisting of Canadian Inuit skeletons curated at the Canadian Museum of Civilization, and the other of 48 individual examples of asymmetrical spondylolysis from sites in a variety of localities curated by several different institutions. The first collection was studied primarily to observe early manifestations of spondylolysis, particularly incomplete separation, while various patterns of asymmetrical complete separation were the focus of the second. The results indicate that asymmetry is part of the earliest osteological picture of spondylolysis, with right-sidedness predominating, a condition perhaps related in some way to handedness. The right-side predominance appears to decrease with age. The ratio of unilateral to bilateral separation ranges from 3-33% in different studies, and a significant number of the unilateral separations have spina bifida occurring in the same vertebra. Overall, the specimens examined here, considered along with clinical cases, nicely illustrate a progression of spondylolysis. A unilateral separation may heal, it may progress to bilateral separation, or it may remain as a permanent condition, producing a pattern of degenerative changes that can include spondylolisthesis. A unilateral healing of bilateral complete separation is likely a rare phenomenon, at least after the separations have reached a certain level of maturity.

Vertebral displacement in spondylolisthesis

The causes of sagittal displacement in 162 patients with isthmic spondylolisthesis and 81 with degenerative spondylolisthesis have been assessed. The slip ratio was compared with joint mobility, the presence of spina bifida, the lumbosacral angle, a self-assessment of previous athletic ability at school and childhood injuries. There was a correlation between the slip ratio and the lumbosacral angle in isthmic spondylolisthesis ( = 0.39, p < 0·01); but this may be secondary. Metacarpophalangeal joint hyperextension correlated with slip ratio (r = 0·26, p < 0·05). There was no significant difference in slip ratio between the patients with and without spina bifida. Those patients with a childhood injury before 11 years of age had greater displacement than those with a later injury, but this did not reach statistical significance. Many patients with degenerative spondylolisthesis rated their athletic ability at school as 'poor'.