Atypical, unusual, and misleading imaging presentations of spondylolysis

Diagnostic Efficacy of Posterior Epidural Fat Interposition on Magnetic Resonance T1-Weighted Sequence in the Diagnosis of Spondylolysis

OBJECTIVE

Supportive radiologic signs may be needed to diagnose spondylolysis (SL) via lumbar magnetic resonance imaging (MRI). In SL, the slight displacement of the corpus forward and lamina posteriorly can cause the interposition of posterior epidural fat (EFI), which is normally segmental. This study aimed to determine the diagnostic value of EFI, an indirect sign of SL, on lumbar mid-sagittal T1-weighted MRI.

METHODS

The lumbar MRI of 115 randomly selected patients with SL and degenerative disc disease (DDD) was randomized and assessed for the presence or absence of EFI by 2 masked observers. These observers were not permitted to examine the pars region. Interobserver agreement was tested using Cohen's kappa coefficient.

RESULTS

EFI was positive in 98 (85%) of 115 patients with SL, 14 (12%) in the DDD group, and 6 (5%) with an upper vertebral level adjacent to the SL. The difference was statistically significant (P < 0.01). In patients with SL, the EFI positivity rate was highest at lumbar 5 vertebrae (94%) and lowest at lumbar 3 vertebrae (33%). The specificity, sensitivity, positive predictive value, negative predictive value, and accuracy of EFI in diagnosing SL were mean 64%, 97%, 80%, 97%, and 95%, respectively. The highest diagnostic value of EFI was at the lumbar 5 vertebrae level, where intraobserver and interobserver reliability were nearly perfect.

CONCLUSIONS

EFI is an indirect radiological finding with high reliability in diagnosing SL with mid-sagittal T1-weighted images in lumbar MRI.

Spondylolysis

Spondylolysis is a bony defect of the pars interarticularis and most often results from repetitive stress. Although spondylolysis is usually asymptomatic, symptomatic spondylolysis is the most common cause of identifiable back pain in children and adolescent athletes. A thorough history and physical exam, as well as appropriate imaging studies are helpful in diagnosis. General first-ine therapy for spondylolysis is conservative and consists of rest from sports, core strengthening, as well as spinal bracing. Patients who have failed conservative therapy may consider surgical repair. This article aims to review the epidemiology, pathophysiology, presentation, and treatment options of spondylolysis.

Increased sagittal diameter of the vertebral arch aids in diagnosis of lumbar spondylolysis

OBJECTIVE

To identify a diagnostic indicator of lumbar spondylolysis visible in plain X-ray films.

METHODS

One hundred and seventy-two patients with low back pain who received X-ray and computerized tomography (CT) examinations were identified and studied. They were divided into three groups: the spondylosis without spondylolisthesis (SWS) group, comprising 67 patients with bilateral pars interarticularis defects at L5 and without spondylolisthesis, the isthmic spondylolisthesis (IS) group, comprising 74 patients with L5/S1 spondylolisthesis and bilateral L5 pars interarticularis defects, and the control group, comprising 31 patients with low back pain but without spondylolysis. The sagittal diameters of the vertebral arch (SDVAs) of L4 and L5 were measured in lateral X-ray image, and the differences in SDVA between L4 and L5 (DSL4-5) in each case were calculated and analyzed.

RESULTS

There were no significant differences in demographic characteristics among the three groups. In the SWS and IS groups, the SDVA of L5 was significantly longer than the SDVA of L4 (p < 0.001), whereas no significant difference found in the control group (p > 0.05). DSL4-5, in which the SDVA of L4 was subtracted from the SDVA of L5, significantly differed among the three groups (p < 0.001), and the normal threshold was provisionally determined to be 1.55 mm.

CONCLUSIONS

In bilateral L5 spondylolysis, the SDVA of L5 is wider than the SDVA of L4, and this difference is greater in isthmic spondylolisthesis. This sign in lateral X-rays may provide a simple and convenient aid for the diagnosis of spondylolysis.

Diagnostic accuracy of MRI for identifying posterior element bone stress injury in athletes with low back pain: a systematic review and narrative synthesis

Objective

To investigate the diagnostic accuracy of MRI for identifying posterior element bone stress injury (PEBSI) in the athletic population with low back pain (LBP).

Study Design

A systematic review searched for published sources up until July 2020. Eligibility criteria: prospective cohort design, MRI diagnosis, adolescents/young adults, chief symptoms of LBP, PEBSI as the clinical diagnosis and SPECT-CT as reference standard. Risk of bias and overall quality were assessed using QUADAS-2 and GRADE, respectively. A narrative synthesis was conducted.

Results

Four studies were included, with three included in the quantitative synthesis. Compared with SPECT-CT, two studies involving MRI demonstrated sensitivity and specificity of 80% and 100%, and 88% and 97%, respectively. Compared with CT, one study involving MRI demonstrated sensitivity and specificity of 97% and 91%, respectively. Risk of bias was moderate to high although consistency across studies was noted.

Conclusion

Findings support further research to consider MRI as the modality of choice for diagnosing PEBSI. MRI was consistent with SPECT-CT for ruling-in PEBSI, but the clinical value of cases where MRI had false negatives remains uncertain due to possible over-sensitivity by SPECT-CT.

PROSPERO registration number

CRD42015023979.

Neural Arch Bone Marrow Edema and Spondylolysis in Adolescent Cheerleaders: A Case Series

Objective

Spondylolysis is 1 of the most common sources of low back pain in children and adolescents; however, there is still a great deal of confusion in regard to etiology, clinical presentation, and diagnostic imaging findings. It is imperative for clinicians to recognize that persistent low back pain is strongly indicative of spondylolysis, especially in high-performance athletes. This case series demonstrates a comprehensive diagnostic spectrum of spondylolysis and its treatment in 2 competitive adolescent cheerleaders.

Clinical Features

In case 1, a 12-year-old female competitive cheerleader presented with a gradual onset of subacute low back pain. Comprehensive clinical examination indicated imaging studies that identified bilateral L5 grade 1 stress reaction, consisting of neural arch bone marrow edema (BME). Treatment included spinal adjustments, rehabilitation, and myofascial therapy. In case 2, 15-year-old female competitive cheerleader presented with insidious chronic low back pain that was provocative with extension. Magnetic resonance imaging revealed a left L5 grade 1 pars interarticularis stress reaction. Computed tomography demonstrated right L5 pars grade 3 and left L5 healing spondylolysis. Treatment included spinal adjustments and rehabilitation exercises. She was also seen by a physical therapist who prescribed a lumbar spine flexion brace.

Intervention and Outcome

Diagnosis of BME and spondylolysis led to temporary cessation of cheerleading activities in cases 1 and 2. The individual in case 1 self-discharged with a list of rehabilitation exercises and was lost to follow-up. The individual in case 2 was able to return to sport pain free approximately 5 weeks after seeking treatment.

Conclusion

Spondylolysis is common in adolescent athletes, and the presence of BME precedes spondylolysis. Primary spine providers could consider this diagnosis in any adolescent, especially an athlete, who has persistent low back pain. Timely diagnosis will optimize treatment outcomes.

The Incidence of Pars Interarticularis Defects in Athletes

STUDY DESIGN

Literature review.

OBJECTIVE

To conduct a literature review of studies reporting the incidence of pars interarticularis defects in athletes of specific sports, in order to allow more targeted prevention and treatment strategies to be implemented for the groups at highest risk.

METHODS

Electronic searches were performed using PubMed, Ovid Medline, EMBASE, Google Scholar, Cochrane Database of Systematic Reviews, and Cochrane Database of Controlled Trials from their dates of inception to September 2017, with the following keywords: "spondylolysis," "sports," "low back pain," and "pars defects."

RESULTS

A total of 509 total articles were retrieved, of which 114 were used in the final review. The incidence of pars interarticularis defects was found to be highest in diving (35.38%), cricket (31.97%), baseball/softball (26.91%), rugby (22.22%), weightlifting (19.49%), sailing (17.18%), table tennis (15.63%), and wrestling (14.74%). Only 5 studies reported the management instituted for their participants, and these were all case reports. Of 74 players with spondylolysis in these studies, 70 (94.59%) underwent conservative treatment and 4 (5.41%) underwent surgical treatment. 61 (82.43%) returned to their previous level of play, 6 (8.11%) retired, and the disposition of the final 7 was not reported.

CONCLUSION

The current medical literature provides good evidence that the incidence of pars interarticularis defects is higher in the athletic population, with the highest incidence in diving. There remains no gold standard protocol for the management of pars interarticularis defects. Further research is required to compare conservative therapy to surgical therapy and to compare the various surgical techniques to each other.

Acquired spondylolysis and spinopelvic sagittal alignment

Acquired spondylolysis represents an uncommon complication of spine surgery, of an unknown incidence and etiology. We studied patients presenting this rare entity, with the purpose to investigate the incidence, imaging findings, patients' clinical characteristics, as well as to provide an interpretation of the mechanisms that may lead to this phenomenon. The presented working hypothesis, regarding etiology, suggests that there is a relation between variations in spinopelvic sagittal alignment and acquired spondylolysis. Between January 2010 and January 2015, six patients presented spondylolysis after short-segment transforaminal lumbar interbody fusion, at a mean time of 43 months after surgery. The preoperative intactness and postoperative defect of pars interarticularis were documented with computed tomography scans in all patients. Standard radiographical spinopelvic parameters were measured before and after surgery. The optimum values of lumbar lordosis (LL) and pelvic incidence minus lumbar lordosis modifier (PI-LL mismatch) were calculated as well. The incidence of acquired spondylolysis was 0.95% among patients with short-segment lumbar fusion. Patients presented high-grade PI with a vertically orientated sacral endplate, while LL was found 9° greater and PI-LL mismatch 9° lower than the respective optimum values, indicating a non-harmonized alignment. In conclusion, acquired spondylolysis, though rare, may occur in patients with high-grade PI and sacral slope, and suboptimal spinopelvic sagittal alignment after lumbar spine surgery, thereby highlighting the importance of detailed preoperative planning in spine surgery, along with the study of sagittal balance.