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Curr Opin Pediatr 2019 Feb;31(1):61-68

Washington University in St. Louis, St. Louis, Missouri, USA.

Purpose Of Review: Provide a comprehensive overview of lumbar spondylolysis, a frequent cause of lower back pain in children and adolescents, from evaluation to management.

Recent Findings: With the surge of structured sports participation in the pediatric population, spondylolysis is a common ailment that afflicts many young athletes due to rigorous competition that taxes the growing spine with repetitive extension and rotation.

Summary: Spondylolysis is a fracture through the pars interarticularis. Read More

Eur J Radiol 2018 Nov 1;108:28-42. Epub 2018 Sep 1.

Fortius Clinic, 17 Fitzhardinghe Street, London W1H 6EQ, United Kingdom. Electronic address:

Injuries of the lumbar neural arch, in particular the pars interarticularis, are widely considered to be due to abnormal bone stress secondary to repetitive loading/shearing, and are a common pathology and a main cause of lower back pain in elite athletes across a range of sports. Medical imaging plays a pivotal role in the diagnosis, monitoring and prognostication of neural arch injury. Early detection is highly desirable in the young elite athlete, as early injuries have been shown to require shorter recovery time and have a higher potential of full healing, whilst accurate grading of injury allows appropriate rehabilitation planning. Read More

World Neurosurg 2018 Nov 24;119:389-393. Epub 2018 Aug 24.

Department of Neurosurgery Charité University Hospital, Berlin, Germany. Electronic address:

Background: Nonlethal cervical spine injuries in skydiving are rare due to the associated high mortality. Here, we report an unusual pathomechanism leading to a Hangman fracture in a semiprofessional parachute athlete.

Case Description: The moment of injury was captured on a first-person video and identified as a rough parachute opening deceleration during canopy deployment, caused by failure of the parachute inflation control device. Read More

World Neurosurg 2018 Nov 9;119:e848-e854. Epub 2018 Aug 9.

Department of Operating Room and Anesthesiology, West China Hospital, Sichuan University, Chengdu, China.

Objective: The literature on surgical management of atypical hangman's fracture (AHF) is sparse. The aim of this study was to describe an individual surgical strategy using a lag screw-rod technique for treatment of unstable AHF based on different fracture patterns.

Methods: A retrospective analysis of 23 patients with unstable AHF was performed. Read More

Acta Neurochir (Wien) 2018 Jun 23. Epub 2018 Jun 23.

Department of Neurosurgery, Postgraduate Institute of Medical Education and Research (PGIMER), Sector 12, Chandigarh, 160012, India.

Congenital craniovertebral junction deformities can be associated with an anomalous vertebral artery (VA). At times, the artery crosses the joint posteriorly (i.e. Read More

Neurochirurgie 2018 Sep 3;64(4):327-330. Epub 2018 May 3.

CHU de Strasbourg, hôpital de Hautepierre, service de neurochirurgie, 67200 Strasbourg, France.

Introduction: Grisel's syndrome consists in rotational subluxation of C1-C2 following ENT infection or surgery. There is no consensus on management. We present 2 cases requiring surgical treatment in our center. Read More

J Med Case Rep 2018 Apr 27;12(1):110. Epub 2018 Apr 27.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kanazawa University, 13-1 Takara-machi, Kanazawa City, Ishikawa, 920-8641, Japan.

Background: Although microendoscopy-assisted lumbar discectomy for lateral or extraforaminal lumbar disc herniations via the lateral approach has previously been reported, microendoscopy-assisted lumbar discectomy for central or paramedian disc herniations via the lateral approach has not been reported. We report the first case of recurrent upper lumbar disc herniation (L2-L3) treated with microendoscopy-assisted lumbar discectomy via the transforaminal approach. No microendoscopy-assisted lumbar discectomy for recurrent upper lumbar disc herniation via the transforaminal approach has previously been reported. Read More

Clin Neurol Neurosurg 2018 Jun 27;169:133-138. Epub 2018 Mar 27.

Department of Neurosurgery, Postgraduate Institute of Medical Education & Research (PGIMER), Chandigarh, India.

Objective: There is lack of consensus on the preferred approach for unstable Hangman's fracture. The associated soft tissue injuries apart from apparent bony injury add to the complexity of dislocation and needs to be addressed. Here, we evaluated the clinico-radiological characteristics and outcome of patients managed by posterior C2-3 fusion. Read More

World Neurosurg 2018 Feb;110:526-532.e10

Department of Radiology and Molecular Imaging, Sultan Qaboos University Hospital, Muscat, Oman.

Background: To date, trabecular morphology studies have been conducted on thin-section computed tomography (CT) scans of cadaveric bone. Here we describe the trabecular anatomy of the axis vertebra as revealed by an innovative imaging tool.

Methods: Ten patients who underwent thin-slice CT scans for suspected cervical spine injury were prospectively subjected to shaded volume-rendered 3-dimensional reconstruction of the images. Read More

Neurol Med Chir (Tokyo) 2018 Feb 25;58(2):91-95. Epub 2017 Dec 25.

Department of Orthopedics, Tokushima University.

Lumbar spondylolysis usually occurs as a stress fracture in the pars interarticularis of the vertebra. It is a prevalent sports-related disorder and a common cause of low back pain. We encountered five athletes (4 males, 1 female) with severe low back pain. Read More

Neurosurg Focus 2017 08;43(2):E2

Department of Neurosurgery, University Medicine Greifswald, Germany; and.

OBJECTIVE In traumatic spondylolistheses of the axis, there is a marked heterogeneity of the observed injury patterns, with a wide range of the severity-from stable fractures, which can be treated conservatively with very good success, to highly unstable fractures, which should be treated surgically. A number of classification systems have been devised to assess the instability of the injuries and to derive a corresponding therapy recommendation. In particular, the results and recommendations regarding medium-severity cases are still inconclusive. Read More

Arch Orthop Trauma Surg 2017 May 27;137(5):685-691. Epub 2017 Mar 27.

Department of Orthopaedic Surgery, Shiga University of Medical Science, Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan.

Background: Stress injuries (stress fractures and stress reactions) of the lumbosacral region are one of the causes of sports-related lower back pain in young individuals. These injuries can be detected by bone marrow edema lesion on MRI. However, little is known about the prevalence and clinical features of early stage lumbosacral stress injuries. Read More

Clin Spine Surg 2017 04;30(3):E233-E238

*Department of Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima †Department of Orthopedics, Teikyo University Mizonokuchi Hospital, Tokyo, Japan.

Study Design: This study was a case series.

Objective: The purpose of this paper was to present a case series of fresh stress fractures (spondylolysis) in the lumbar spines of adult athletes.

Summary Of Background Data: Lumbar spondylolysis is a stress fracture of the pars interarticularis, which is generally considered a disease of children or adolescence. Read More

World Neurosurg 2017 Apr 27;100:583-589. Epub 2017 Jan 27.

Department of Neurosurgery, MedStar Georgetown University Hospital, Washington, DC, USA. Electronic address:

Background: Upper lumbar disc herniations comprise only 1%-2% of all lumbar disc herniations. Patients exhibit nonspecific signs and symptoms in comparison to predictable radiculopathies, as seen in lower lumbar disc herniations. The unique anatomic characteristics of the upper lumbar spine present several challenges for safe and effective surgical treatment of disc herniations. Read More

J Neurosurg Spine 2017 Mar 2;26(3):341-345. Epub 2016 Dec 2.

New York University School of Medicine, New York, New York.

The authors report on an 81-year-old woman with a pathologic hangman's fracture secondary to a complex arteriovenous fistula (AVF). The patient presented with severe, unremitting neck pain and was found to have fractures bilaterally through the pars interarticularis of C-2 with significant anterior subluxation of C-2 over C-3 along with widening of the left transverse foramen. Due to an abnormally appearing left vertebral artery (VA) on CT angiography, the patient underwent conventional angiography, which revealed a complex AVF stemming from the left VA at the level of C-2 with dilated posterior cervical veins and a large venous varix. Read More

J Neurosurg Spine 2017 Feb 30;26(2):190-198. Epub 2016 Sep 30.

Department of Neurosurgery and.

OBJECTIVE The goal of this study was to demonstrate the clinical and technical nuances of a minimally invasive, dorsolateral, tubular approach for partial odontoidectomy, autologous bone augmentation, and temporary C1-2 fixation to treat dens pseudarthrosis. METHODS A cadaveric feasibility study, a 3D virtual reality reconstruction study, and the subsequent application of this approach in 2 clinical cases are reported. Eight procedures were completed in 4 human cadavers. Read More

Skeletal Radiol 2016 Nov 10;45(11):1533-40. Epub 2016 Sep 10.

Victoria House Medical Imaging, 316 Malvern Road, Prahran, Victoria, Australia.

Objective: To compare the diagnostic accuracy of 3-T magnetic resonance imaging (MRI) with thin-slice 3D T1 VIBE sequence to 128-slice computer tomography (CT) in pars stress fractures of the lumbar spine.

Materials And Methods: 3-T MRI and CT of 24 patients involving 70 pars interarticularis were retrospectively reviewed by four blinded radiologists. The fracture morphology (complete, incomplete, or normal) was assessed on MRI and CT at different time points. Read More

Spine (Phila Pa 1976) 2016 Oct;41 Suppl 19:B6-B13

Department of Orthopaedic Surgery, Affiliated Xinqiao Hospital, The Third Military Medical University, Chongqing, People's Republic of China.

Study Design: A retrospective analysis of the clinical outcomes of eight patients with the lumbar pars interarticulars defects treated by direct repair with the aid of intraoperative O-arm based navigation and microendoscopic techniques.

Objective: The aim of this study was to investigate the efficacy and safety of direct screw repair by using minimally invasive surgery for the lumbar pars interarticulars defects in a pilot study.

Summary Of Background Data: Direct repair of pars interarticulars defects has been used to treat young adult patients. Read More

World Neurosurg 2016 Sep 17;93:279-85. Epub 2016 Jun 17.

Intermountain Medical Center, Murray, Utah, USA; Department of Neurosurgery, University of Utah, Salt Lake City, Utah, USA. Electronic address:

Background: Acute complex C2 vertebral body fracture specifically does not involve the odontoid process or C2 pars interarticularis. External stabilization can be effective but may prolong healing and increase morbidity. Many traditional surgical techniques can achieve internal stabilization at the expense of normal cervical motion. Read More

Phys Ther Sport 2016 Jul 13;20:56-60. Epub 2016 Apr 13.

University of Wisconsin Hospitals and Clinics, Sports Rehabilitation, 4602 East Park Blvd., Madison, WI, 53718, United States. Electronic address:

Introduction: Spondylolysis is a common occurrence for adolescent athletes who have low back pain. The injury involves a defect in the pars interarticularis, occurring as a result of repeated hyperextension and rotation.

Clinical Presentation: Clinical findings might include tightness of the hip flexors and hamstrings, weakness of the abdominals and gluteals, and an excessive lordotic posture. Read More

Orthopedics 2016 May 12;39(3):e434-7. Epub 2016 Apr 12.

Lumbar spondylolysis, a stress fracture of the pars interarticularis, is prevalent in adolescent athletes. Recent advances in diagnostic tools and techniques enable early diagnosis before these fractures progress to complete fractures through the pars. However, because patients often consult family physicians for primary care of low back pain and these physicians may not have access to diagnostic modalities such as magnetic resonance imaging (MRI) and computed tomography, stress fractures can be missed. Read More

J Med Invest 2016 ;63(1-2):119-21

Department of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School.

Spondylolysis, a defect or stress fracture of the vertebral pars interarticularis, occurs most frequently in the lower lumbar spine and occasionally in the cervical spine, but is extremely rare in the thoracic spine. We report the case of a 17 year-old girl, an elite rhythmic gymnast, who reported with early-stage thoracic spondylolysis at T10 and T11 levels. Physicians should be aware that performance of unusual athletic movements, such as those by gymnasts, may lead to spondylolysis in rare locations. Read More

Neurosurg Focus 2016 Feb;40(2):E12

Department of Neurosurgery, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island.

OBJECTIVE The authors describe a cadaveric analysis to determine the ideal dimensions and trajectory for considering endoscopic transforaminal interbody implantation. METHODS The soft tissues of 8 human cadavers were removed from L-1 to the sacrum, exposing the posterior bony elements. Facetectomies were performed bilaterally at each lumbar level with resection of the pars interarticularis, revealing the pedicles, nerve roots, and interbody disc space. Read More

Br J Neurosurg 2017 Apr 13;31(2):273-274. Epub 2016 Jan 13.

a Spine and Spinal Cord Center, Mita Hospital, International University of Health and Welfare , Tokyo , Japan.

Background Fractures of the superior articular process are rarely seen in clinical practice. Repetitive spinal movements may lead to fractures of the pars interarticularis, resulting in spondylolysis. Traumatic spinal fractures often involve the vertebral body, transvers and/or the spinous processes. Read More

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2015 Oct;29(10):1244-8

Objective: To analyze the effectiveness of direct screw repair for lumbar spondylolysis by using intraoperative O-arm based navigation and microendoscopic techniques.

Methods: Between February 2012 and May 2014, 11 consecutive patients with lumbar spondylolysis were treated with Buck's procedure by the aid of intraoperative O-arm based navigation and minimally invasive approach. The debridement and autograft of pars interarticularis defects was performed under microendoscopy. Read More

Am J Orthop (Belle Mead NJ) 2015 Dec;44(12):E526-9

Department of Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH.

Lumbar spondylolysis is a well-recognized condition occurring in adolescents because of repetitive overuse in sports. Nonconsecutive spondylolysis involving the lumbar spine is rare. In contrast to single-level pars defects that respond well to conservative treatment, there is no consensus about the management of multiple-level pars fractures; a few reports indicated that conservative management is successful, and the majority acknowledged that surgery is often required. Read More

JBI Database System Rev Implement Rep 2015 Apr 17;13(3):137-73. Epub 2015 Apr 17.

Joanna Briggs Institute, Faculty of Health Sciences, The University of Adelaide, South Australia.

Background: Spondylolysis is a common cause of low back pain in athletes. Historically, spondylolysis injuries were thought to be mostly bilateral; however advances in lumbar spine imaging have shown that in certain athlete groups, unilateral spondylolysis is highly prevalent. It remains unclear whether athletes with unilateral spondylolysis who undergo surgical repair are able to return to sports as effectively or faster than if they had conservative treatment. Read More

Clin Neurol Neurosurg 2015 Dec 28;139:29-34. Epub 2015 Aug 28.

Department of Neurosurgery, Rush University Medical Center, Chicago, IL, United States. Electronic address:

Objectives: To understand that young athletes have a higher incidence of pars interarticularis defects than the general population. This may be due to an immature spine put under higher stress loads at an early age. Traditionally, surgery was reserved for those who failed conservative therapy, and consisted of open exposure, bone grafting and placement of pedicle screws. Read More

Eur Spine J 2016 06 26;25(6):1651-4. Epub 2015 Jul 26.

Royal National Orthopaedic Hospital, Stanmore, London, UK.

Purpose: A conventional midline posterior approach is used for most of the described surgical techniques. We describe a technique of percutaneous fixation of the pars interarticularis, augmented where necessary by grafting the defect, which minimises muscle injury.

Method: A 4. Read More

Radiographics 2015 May-Jun;35(3):819-34

From the Department of Radiology, Divisions of Nuclear Medicine (A.T.T., S.E.S., C.G.A., M.J.G.) and Pediatric Orthopaedic Surgery (C.T.M.), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH 45229.

Single photon emission computed tomography (SPECT)/computed tomography (CT) is ideally suited for assessment of low back pain in children and young adults. Spondylolysis is one of the most common structural causes of low back pain and is readily identified and characterized in terms of its chronicity and likelihood to heal. The value of SPECT/CT extends to identification and characterization of other causes of low back pain, including abnormalities of the posterior elements, developing vertebral endplate, transverse processes, and sacrum and sacroiliac joint. Read More

World Neurosurg 2015 Nov 7;84(5):1494.e7-12. Epub 2015 May 7.

Neurosurgery Department, AORN Santobono-Pausilipon-Annunziata Children's Hospital, Naples, Italy.

Background: Grisel syndrome is a nontraumatic rotatory subluxation of the atlantoaxial joint, following nasopharyngeal inflammation or ear, nose, and throat (ENT) procedures. The syndrome should be suspected in cases of persistent neck pain and stiffness, especially after ENT surgical procedures. The primary treatment of early detected Grisel syndrome is conservative. Read More

J Med Invest 2015 ;62(1-2):11-8

Department of Orthopedics, Tokushima University.

Spondylolysis is a stress fracture of the pars interarticularis, which in some cases progresses to spondylolisthesis (forward slippage of the vertebral body). This slip progression is prevalent in children and occurs very rarely after spinal maturation. The pathomechanism and predilection for children remains controversial despite considerable clinical and basic research into the disorder over the last three decades. Read More

Springerplus 2014 13;3:672. Epub 2014 Nov 13.

Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Tokyo, 160-8582 Shinjuku-ku Japan.

Introduction: Although pedicle or lateral mass screws are usually chosen to fix atlantoaxial (C1-C2) instability, there is an increased risk for vertebral artery (VA) injury when used in patients with bone or arterial anomalies or osteoporotic bone. Here we report the C1 posterior arch screw as a new technique for upper cervical fixation.

Case Description: A 90-year-old man complained of upper cervical pain after falling in his house. Read More

Br J Neurosurg 2015 Apr 4;29(2):260-4. Epub 2014 Dec 4.

Department of Neurosurgery, G.B. Pant Hospital and Associated Maulana Azad Medical College (University of Delhi) , New Delhi , India.

Background: The surgical management of the craniocervical junction is challenging. Rigid posterior fixation of occiput/C1-C2 can be performed using a variety of surgical techniques including C2 pedicle/pars interarticularis, transarticular and intralaminar screw fixations.

Methods: Forty-one patients were treated with occipital plate/C1 lateral mass and C2 intra-laminar screw fixations for basilar invagination and congenital atlantoaxial subluxation, post-traumatic instability, tuberculous and rheumatoid arthritis-associated atlantoaxial dislocation. Read More

Clin Biomech (Bristol, Avon) 2014 Sep 6;29(8):906-11. Epub 2014 Jul 6.

Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA. Electronic address:

Background: We investigated mechanisms of axis ring fractures due to simulated head impacts.

Methods: Our model consisted of a human upper cervical spine specimen (occiput through C3) mounted to a surrogate torso mass on a sled and carrying a surrogate head. We divided 13 specimens into 3 groups based upon head impact location: upper forehead in the midline, upper lateral side of the forehead, and upper lateral side of the head. Read More

J Pediatr Orthop 2015 Apr-May;35(3):271-5

*Brooke Army Medical Center, Fort Sam, Houston, TX †Department of Orthopaedic Surgery, Le Bonheur Children's Hospital, University of Tennessee-Campbell Clinic, Memphis, TN.

Background: In early studies, magnetic resonance imaging (MRI) had low sensitivity and positive predictive value in the evaluation of the pars interarticularis pathology; however, more recent reports have suggested an expanded role for MRI. The purpose of the present study was to evaluate the effectiveness of MRI in the diagnosis of pars injuries and compare it to computed tomography (CT), which was used as the reference "gold standard" for the detection of fractures.

Methods: The radiographic and clinic data of 93 adolescents and young adults with a presumptive diagnosis of spondylolysis based upon history and clinic examination were reviewed. Read More

Bone Joint J 2014 Jun;96-B(6):717-23

Royal National Orthopaedic Hospital, Spinal Surgical Unit, Brockley Hill, Stanmore HA7 4LP, UK.

Back pain is a common symptom in children and adolescents. Here we review the important causes, of which defects and stress reactions of the pars interarticularis are the most common identifiable problems. More serious pathology, including malignancy and infection, needs to be excluded when there is associated systemic illness. Read More

J Spinal Disord Tech 2014 Jun;27(4):232-6

Department of Neurosurgery, University of South Florida, Tampa, FL.

Study Design: Retrospective review/case series.

Objective: This study aims to present the clinical feasibility of condylar fixation in occipitocervical (OC) fusion. Here, we present the largest clinical series to date of patients who underwent OC fusion via cervicocondylar fixation using a polyaxial screw/rod construct. Read More

Skeletal Radiol 2014 Jul 2;43(7):925-32. Epub 2014 Apr 2.

Department of Radiology, Chelsea and Westminster Hospital NHS Foundation Trust, 369 Fulham Road, London, SW10 9NH, England, UK,

Objective: To evaluate the MRI findings in the lumbar spines of asymptomatic elite junior tennis players.

Materials And Methods: The lumbar spine MRI studies of 98 asymptomatic junior elite tennis players (51 male, 47 female) with a mean age of 18 years (age range 11.2-26. Read More

J Neurosurg Pediatr 2014 May 14;13(5):548-52. Epub 2014 Mar 14.

Department of Pediatric Neurosurgery, Regional Center for Pediatric Neurosurgery;

The authors report the first case of unilateral traumatic rupture of the C-2 neurocentral synchondrosis. A 26-month-old child was in a vehicular collision that caused his head to be rotated sharply to the left with the neck flexed. He had severe neck pain but was neurologically normal. Read More

J Athl Train 2014 Mar-Apr;49(2):274-9. Epub 2014 Feb 12.

Human Performance, Dance, and Recreation Department, New Mexico State University, Las Cruces.

Objective: To introduce the characteristics of a Chance fracture and increase awareness of the mechanism of injury that may occur during athletic activity.

Background: A T12 Chance fracture was diagnosed in an 18-year-old male rodeo athlete. The rider was forced into extreme lumbothoracic hyperflexion when the horse bucked within the chute, pinning the rider's legs to his chest. Read More

Eur Spine J 2014 Jun 30;23(6):1346-53. Epub 2014 Jan 30.

Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.

Purpose: The proportion of load transmitted through the lumbar neural arch increases with aging, spinal degeneration, and lordosis, effectively shielding the lumbar vertebral bodies from load. This stress shielding may contribute to bone loss in the vertebral body, leading to increased fracture risk. To test his hypothesis, we performed a study to determine if vertebral body fractures were associated with a higher neural arch/vertebral body volumetric bone mineral density (vBMD) ratio. Read More

J Neurosurg Pediatr 2014 Feb 20;13(2):196-203. Epub 2013 Dec 20.

Division of Pediatric Neurosurgery, Texas Children's Hospital, and Department of Neurosurgery, Baylor College of Medicine, Houston, Texas;

Object: Cervical spondylolysis is a rare condition that results from a pars interarticularis defect. The C-6 level is the most frequently involved site in the cervical spine. Its clinical presentations range from incidental radiographic findings to neck pain and, rarely, neurological deficits. Read More

Spine J 2014 Apr 21;14(4):675-82. Epub 2013 Nov 21.

The Centre for Spinal Studies and Surgery, Queens Medical Centre, Derby Road, Nottingham, NG72UH, UK.

Background: The biomechanical effect of a bifid arch as seen in spina bifida occulta and following a midline laminectomy is poorly understood.

Purpose: To test the hypothesis that fatigue failure limits will be exceeded in the case of a bifid arch, but not in the intact case, when the segment is subjected to complex loading corresponding to normal sporting activities.

Study Design: Finite element analysis. Read More

J Neurosurg Spine 2014 Jan 1;20(1):5-10. Epub 2013 Nov 1.

Departments of Neurosurgery and.

Object: Stabilization of the craniovertebral junction (CVJ) by using lateral masses requires extensive dissection. The vertebral artery (VA) is commonly anomalous in patients with congenital CVJ anomaly. Such a vessel is likely to be injured during dissection or screw placement. Read More

Comput Methods Biomech Biomed Engin 2015 15;18(5):545-55. Epub 2013 Aug 15.

a Canadian Memorial Chiropractic College , Toronto , Ontario , Canada.

The mechanism of vertebral shear failure is likely a bending moment generated about the pars interarticularis by facet contact, and the moment arm length (MAL) between the centroid of facet contact and the location of pars interarticularis failure has been hypothesised to be an influential modulator of shear failure force. To quantitatively evaluate this hypothesis, anterior shear of C3 over C4 was simulated in a finite element model of the porcine C3-C4 vertebral joint with each combination of five compressive force magnitudes (0-60% of estimated compressive failure force) and three postures (flexed, neutral and extended). Bilateral locations of peak stress within C3's pars interarticularis were identified along with the centroids of contact force on the inferior facets. Read More

J Pediatr Orthop 2013 Jun;33(4):383-8

Department of Orthopedic Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.

Background: Evaluation of extension-based low back pain in young athletes with suspected pars injury may include a referral for skeletal single photon emission computed tomography (SPECT). However, the diagnostic yield of this technique in children with low back pain before the age of 10 years remains uncertain. We examined a series of consecutive SPECT scans to address this question. Read More

Clin Biomech (Bristol, Avon) 2013 Mar 27;28(3):246-54. Epub 2013 Jan 27.

Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.

Background: Injury models for spondylolytic fracture of the pars interarticularis have long considered repetitive shear loading as a risk factor without quantifying the relationship between shear force magnitude and fatigue life. This investigation sought to quantify the relationship using a basic in vitro approach.

Methods: Thirty-two (16 C3-C4, 16 C5-C6) porcine cervical specimens were exposed to repetitive shear loading to 20%, 40%, 60%, or 80% of their calculated ultimate anterior shear failure tolerance. Read More

Med Eng Phys 2013 Aug 20;35(8):1212-20. Epub 2013 Jan 20.

Department of Graduate Education and Research Programs, Canadian Memorial Chiropractic College, Toronto, Ontario, Canada.

Equations used to determine vertebral failure tolerances without the need for destructive testing are useful for scaling applied sub-maximal forces during in vitro repetitive loading studies. However, existing equations that use vertebral bone density and morphology for calculating compressive failure tolerance are unsuitable for calculating vertebral shear failure tolerance since the primary site of failure is the pars interarticularis and not the vertebral body. Therefore, this investigation developed new equations for non-destructively determining vertebral shear failure tolerance from morphological and/or bone density measures. Read More