Anatomy and Examination of the Spine

New Insights in the Pathophysiology, Epidemiology, and Response to Treatment of Osteoporotic Vertebral Fractures

CONTEXT

Vertebral fractures (VFs) make up an important but challenging group of fractures often caused by osteoporosis. Osteoporotic fractures pose unique diagnostic challenges in generally requiring imaging for diagnosis. The objective of this narrative mini-review is to provide an overview of these recent advances in our knowledge of VF pathophysiology and epidemiology with particular focus on endocrine diseases, prevention, and treatment.

EVIDENCE ACQUISITION

We searched PubMed on May 23, 2022, for studies of VFs in humans. Results were limited to papers available as full-text publications in English, published from 2020 and onward. This yielded 3457 citations. This was supplemented by earlier publications selected to add context to the recent findings.

EVIDENCE SYNTHESIS

Studies addressed VF risk in hyperthyreosis, hyperparathyroidism, acromegaly, Cushing syndrome, primary aldosteronism, and diabetes. For pharmaceutical treatment, new studies or analyses were identified for romosozumab and for weekly teriparatide. Several studies, including studies in the immediate pipeline, were intervention studies with vertebroplasty or kyphoplasty, including combination with stem cells or pharmaceuticals.

CONCLUSIONS

Endocrinologists should be aware of the high likelihood of osteoporotic VFs in patients with endocrine diseases. Though licensed treatments are able to substantially reduce the occurrence of VFs in patients with osteoporosis, the vast majority of recent or ongoing randomized controlled trials in the VF area focus on advanced invasive therapy of the fracture itself.

Pyroptosis and Intervertebral Disc Degeneration: Mechanistic Insights and Therapeutic Implications

Low back pain (LBP) is a common problem worldwide, resulting in great patient suffering and great challenges for the social health system. Intervertebral disc (IVD) degeneration (IVDD) is widely acknowledged as one of the key causes of LBP. Accumulating evidence suggests that aberrant pyroptosis of IVD cells is involved in the pathogenesis of IVDD progression, however, the comprehensive roles of pyroptosis in IVDD have not been fully established, leaving attempts to treat IVDD with anti-pyroptosis approaches questionable. In this review, we summarize the characteristics of pyroptosis and emphasize the effects of IVD cell pyroptosis on the pathological progression of IVDD, including secretion of cytokines, nucleus pulposus cell apoptosis and autophagy, accelerated extracellular matrix degradation, annulus fibrosus rupture, cartilage endplate calcification, vascularization, sensory and sympathetic fiber neoinnervation, and infiltrating lymphatic vessels. Finally, we discuss several interventions used to treat IVDD by targeting pyroptosis. This review provides novel insights into the crucial role of IVD cell pyroptosis in IVDD pathogenesis, and could be informative for developing novel therapeutic approaches for IVDD and LBP.

Preoperative Cervical Cobb Angle Is a Risk Factor for Postoperative Axial Neck Pain after Anterior Cervical Discectomy and Fusion with Zero-Profile Interbody

OBJECTIVES

Anterior cervical discectomy and fusion (ACDF) with zero-profile interbody has a lower incidence of complications in treating cervical spondylotic myelopathy (CSM). However, postoperative axial neck pain is still commonly occurred, and the factors affecting which is not known. Here, we retrospectively analyze the risk factors for postoperative axial pain after performing ACDF with zero-profile implant in single-level CSM.

METHODS

Patients who suffered from single-level CSM and who received ACDF with zero-profile implant between 2018 January to 2020 December were reviewed. Of 180 single-level CSM patients, 144 patients who passed the inclusion criteria were enrolled. Patients were divided into two groups according to the severity of postoperative axial pain as measured by postoperative neck visual analogue scale (nVAS). Clinical parameters including age, sex, smoking history, symptom duration, body mass index (BMI), the Japanese Orthopaedic Association (JOA) scores, as well as radiological parameters were obtained pre- and post-operatively, and the data were compared between two groups. Pearson's chi-square tests and Mann-Whitney U tests were implemented to identify statistically significant differences between subgroups for categorical and continuous data, respectively; otherwise, the data were tested with Student's t-test. Risk factors were identified using logistic regression.

RESULTS

Of the patients (97.8%) achieved satisfied neurological recovery, and 88.2% of the patients achieved fusion at 1-year follow-up. 33% of the patients (48 patients out of 144) had sustained postoperative axial pain after the surgery. Comparison of different severity groups exhibited no significant differences in terms of the possible risk factors (P > 0.05) except for pre- and post-operative C2-C7 Cobb angles (6.33 ± 6.53 vs. 11.88 ± 7.41, P < 0.05; 13.49 ± 5.31 vs 16.64 ± 7.34, P < 0.05). Furthermore, correlation analysis showed that the preoperative C2-C7 Cobb angle is significantly correlated with the severity of the postoperative axial pain (R²  = 0.83, P < 0.01). In addition, logistic regression analysis demonstrated that the preoperative C2-C7 Cobb angle is an independent predictor of postoperative axial pain (P < 0.01, OR = 0.53). Further receiver operating characteristic (ROC) analysis displayed an area under the curve (AUC) of 0.78 (P < 0.01) for preoperative C2-C7 Cobb angle, and the optimal cutoff was 8.4° (sensitivity 0.77, specificity 0.65).

CONCLUSION

The pre-operative C2-C7 Cobb angle is a risk factor for severe postoperative axial pain after anterior cervical discectomy and fusion with zero-profile interbody, and we should be cautious when poor preoperative C2-C7 Cobb angle is found in myelopathy patients planning to use zero-profile interbody to treat such patients.

Gait asymmetry of lower extremities reduced immediately after minimally invasive surgery among patients with lumbar disc herniation

BACKGROUND

Lumbar disc herniation patients with increased pain exhibit greater gait asymmetry in stance time, swing time and single support time. Percutaneous endoscopic lumbar discectomy, as a minimally invasive surgical procedure has been used to treat patients with lumbar disc herniation. The objective of this study was to evaluate the immediate impact of the percutaneous endoscopic lumbar discectomy on gait asymmetry in spatiotemporal and kinetic parameters among lumbar disc herniation patients.

METHODS

Marker trajectories and ground reaction forces were measured during walking among 67 lumbar disc herniation patients and 15 healthy controls. Spatiotemporal gait parameters were analyzed via Visual3D. Muscle force and joint contact force were calculated with OpenSim. Gait asymmetry of those parameters were assessed with asymmetry index.

FINDINGS

After surgery, gait asymmetry in gait cycle time, step length, peak biceps femoris long head, tensor fasciae latae and rectus femoris muscle forces, and peak hip and knee joint contact forces reduced immediately. Postoperatively, increased gait cycle time and decreased step length were found in the affected side. Moreover, decreased peak biceps femoris long head, tensor fasciae latae and rectus femoris muscle forces, and peak hip joint contact force were observed in the contralateral side.

INTERPRETATION

These results suggested compensation strategy that biceps femoris long head, tensor fasciae latae and rectus femoris in the contralateral side were mainly used to compensate the affected side preoperatively in lumbar disc herniation patients, with less compensation between lower limbs after surgery, which may provide an insight into postoperative rehabilitation.

SYSTEMIC CYTOKINE LEVEL DIFFERENCES IN PATIENTS WITH CHRONIC MUSCULOSKELETAL SPINAL PAIN COMPARED TO HEALTHY CONTROLS AND ITS ASSOCIATION WITH PAIN SEVERITY: A SYSTEMATIC REVIEW

OBJECTIVE

Although there has been increasing interest in the role of systemic cytokines in chronic spinal pain (CSP), the evidence on their potential contribution is still unclear. Therefore, the current study systematically reviewed the evidence on systemic cytokine level differences between people with CSP compared to healthy controls (HCs) and the potential associations with pain severity.

METHODS

An electronic search was conducted on PubMed, Web of Science and Embase. All included studies were classified as observational studies, exploring the comparison between a CSP group and a HC group, and the association between systemic cytokine levels and pain severity.

RESULTS

Nine articles were included with a total sample of 400 CSP patients suffering from chronic whiplash associated disorder (CWAD) or chronic low back pain (CLBP). In CLBP, moderate evidence was found for elevated tumor necrosis factor (TNF) α, interleukin (IL) 6, IL-1 receptor antagonist (IL-1RA), and soluble TNF receptor (sTNF-R) type 2, for normal interferon (IFN) γ and IL-2 levels, and for reduced IL-10 levels. No association was found between pain severity and these cytokines in CLBP. In CWAD, moderate evidence was found for elevated CRP and evidence for changes in TNF-α was inconclusive. Evidence for the association between pain severity and CRP was limited, and there is probably no association between pain severity and TNF-α with limited evidence in CWAD.

CONCLUSIONS

Moderate evidence indicates the presence of systemic inflammation in CSP. Evidence regarding the association between pain severity and systemic cytokines is inconclusive and limited.

Lumbar nerve root biopsy with fascicle dissection and functional mapping: how I do it

BACKGROUND

Lumbosacral plexopathies with unclear etiology are a rare entity. In certain cases, if workup unrevealing and medical management is suboptimal, an open lumbar nerve root biopsy may be considered.

METHOD

A standard lumbar laminectomy is performed for access to the intradural contents. The dura is opened at midline in a standard fashion. Single nerve roots are selected and stimulated for an EMG response. A nerve fascicle is then dissected and stimulated before excision.

CONCLUSION

Lumbar nerve root biopsy is feasible and safe. All non-invasive workup needs to be completed and negative before performing this procedure.

Recovery after inadvertent intramedullary microchip implantation at C1–C2 in a kitten

Case summary

A 15-week-old male British Shorthair cat was presented for peracute paralysis immediately after microchip implantation. Neurological examination revealed a non-ambulatory tetraparesis and left thoracic limb plegia localised to C1–C5 spinal cord segments. CT of the cervical spine showed a diagonally orientated metallic foreign body (microchip transponder, 10 mm in length) within the vertebral canal at the level of C1–C2, resulting in a penetrating spinal cord injury. Based on concerns about further iatrogenic spinal cord injury through surgery, medical management was chosen. Despite the severe clinical signs, the kitten returned to ambulation within 6 days of the injury, with controlled urination and defecation. Continuous neurological improvement was seen for up to 6 weeks after the injury at which point a mild-to-moderate ambulatory tetraparesis and ataxia remained, with an overall good quality of life. Follow-up CT at the age of 13 months revealed a relative cranial displacement and rotation of the microchip towards the foramen magnum, while the cat’s neurological status was unchanged.

Relevance and novel information

This case demonstrated a cervical penetrating spinal cord injury in a growing cat caused by a microchip, which was successfully managed with medical treatment, suggesting that this might be an option for patients at risk of severe surgery-related complications or where owners reject surgery.

Intervertebral Disk Degeneration: The Microenvironment and Tissue Engineering Strategies

Intervertebral disk degeneration (IVDD) is a leading cause of disability. The degeneration is inevitable, and the mechanisms are complex. Current therapeutic strategies mainly focus on the relief of symptoms, not the intrinsic regeneration of the intervertebral disk (IVD). Tissue engineering is a promising strategy for IVDD due to its ability to restore a healthy microenvironment and promote IVD regeneration. This review briefly summarizes the IVD anatomy and composition and then sets out elements of the microenvironment and the interactions. We rationalized different scaffolds based on tissue engineering strategies used recently. To fulfill the complete restoration of a healthy IVD microenvironment, we propose that various tissue engineering strategies should be combined and customized to create personalized therapeutic strategies for each individual.

Opinion Piece: Patient-Specific Implants May Be the Next Big Thing in Spinal Surgery

The emergence of 3D-Printing technologies and subsequent medical applications have allowed for the development of Patient-specific implants (PSIs). There have been increasing reports of PSI application to spinal surgery over the last 5 years, including throughout the spine and to a range of pathologies, though largely for complex cases. Through a number of potential benefits, including improvements to the implant–bone interface and surgical workflow, PSIs aim to improve patient and surgical outcomes, as well as potentially provide new avenues for combating challenges routinely faced by spinal surgeons. However, obstacles to widespread acceptance and routine application include the lack of quality long-term data, research challenges and the practicalities of production and navigating the regulatory environment. While recognition of the significant potential of Spinal PSIs is evident in the literature, it is clear a number of key questions must be answered to inform future clinical and research practices. The spinal surgical community must selectively and ethically continue to offer PSIs to patients, simultaneously allowing for the necessary larger, comparative studies to be conducted, as well as continuing to provide optimal patient care, thereby ultimately determining the exact role of this technology and potentially improving outcomes.

Clinical Presentations of Lumbar Disc Degeneration and Lumbosacral Nerve Lesions

Lumbar disc degeneration is defined as the wear and tear of lumbar intervertebral disc, and it is mainly occurring at L3-L4 and L4-S1 vertebrae. Lumbar disc degeneration may lead to disc bulging, osteophytes, loss of disc space, and compression and irritation of the adjacent nerve root. Clinical presentations associated with lumbar disc degeneration and lumbosacral nerve lesion are discogenic pain, radical pain, muscular weakness, and cutaneous. Discogenic pain is usually felt in the lumbar region, or sometimes, it may feel in the buttocks, down to the upper thighs, and it is typically presented with sudden forced flexion and/or rotational moment. Radical pain, muscular weakness, and sensory defects associated with lumbosacral nerve lesions are distributed on lower extremities, the buttock, lower abdomen, and groin region. A lumbosacral plexus lesion presents different symptoms in the territories of the lumbar and sacral nerves. Patients with lumbar plexus lesion clinically present with weakness of hip flexion, knee extension, thigh adduction, and sensory loss in the lower abdomen, inguinal region, and over the entire medial, lateral, and anterior surfaces of the thigh and the medial lower leg, while sacral plexus lesion presents clinical symptoms at nerve fibers destined for the sciatic nerve, common peroneal nerve, and pudendal nerve. Weakness of ankle inversion, plantar flexion, and foot drop are the main clinical manifestations of the sacral plexus lesion area. Numbness and decreased sensation are also present along the anterolateral calf and dorsum of the foot. On examination, foot eversion is usually stronger than foot dorsiflexion. The patients may also present with pain and difficulty of bowel movements, sexual dysfunction assessments, and loss of cutaneous sensation in the areas of the anal canal, anus, labia major, labia minor, clitoris, penis, and scrotum.

The Pathways and Processes Underlying Spinal Transmission of Low Back Pain: Observations From Dorsal Root Ganglion Stimulation Treatment

BACKGROUND

Dorsal root ganglion stimulation (DRG-S) is a novel approach to treat chronic pain. Lead placement at L2 has been reported to be an effective treatment for axial low back pain (LBP) primarily of discogenic etiology. We have recently shown, in a diverse cohort including cases of multilevel instrumentation following extensive prior back surgeries, that DRG-S lead placement at T12 is another promising target. Local effects at the T12 DRG, alone, are insufficient to explain these results.

MATERIALS AND METHODS

We performed a literature review to explore the mechanisms of LBP relief with T12 DRG-S.

FINDINGS

Branches of individual spinal nerve roots innervate facet joints and posterior spinal structures, while the discs and anterior vertebrae are carried via L2, and converge in the dorsal horn (DH) of the spinal cord at T8-T9. The T12 nerve root contains cutaneous afferents from the low back and enters the DH of the spinal cord at T10. Low back Aδ and C-fibers then ascend via Lissauer's tract (LT) to T8-T9, converging with other low back afferents. DRG-S at T12, then, results in inhibition of the converged low back fibers via endorphin-mediated and GABAergic frequency-dependent mechanisms. Therefore, T12 lead placement may be the optimal location for DRG-S to treat LBP.

T12 Dorsal Root Ganglion Stimulation to Treat Chronic Low Back Pain: A Case Series

INTRODUCTION

Dorsal root ganglion stimulation (DRG-S) is a neuromodulation technique for treating neuropathic pain syndromes. Research has demonstrated DRG-S to be more effective than conventional SCS in treating RSD/CRPS, particularly of the lower extremities. Results from recent case series and prospective studies suggest that DRG-S may be effective in treatment of pain syndromes considered to have non-neuropathic components and characteristics (e.g. nociceptive). There have been multiple, small studies demonstrating efficacy of DRG-S for axial low back pain. There has, however, been no consensus regarding the best location for DRG lead placement in the treatment of low back pain.

METHODS

Patients presenting with refractory low back pain in a private pain management practice were considered for DRG-S. Patients were provided a trial stimulator prior to potential implantation. Per standard practice, pain intensity, disability, general health status, and quality of life were followed using the visual analog scale (VAS), Oswestry Disability Index, EQ-5D index, and the SF-36 survey, respectively. Data were collected prior to implantation and at variable follow-ups after DRG-S initiation.

RESULTS

Seventeen consecutive patients presented with predominantly axial low back pain with/without a secondary component of lower extremity pain. All were trialed and subsequently implanted for DRG-S. Leads were placed at T12 to target the low back. Stimulation levels were set very low, below that of which patients experienced paresthesias. Last follow-up times averaged 8.3 months. More than half of the patients experienced pain relief ≥80%, with an average low back pain relief of 78% at last follow-up. Additionally, substantial improvements in physical and mental functioning, disability, and quality of life were reported.

CONCLUSIONS

T12 DRG-S can be an effective treatment for chronic axial low back pain. Stimulation results in reduced pain and disability, while improving quality of life. These outcomes can be achieved without paresthesias.

Contrast Spread in the Superoposterior Approach of Transforaminal Epidural Steroid Injections for Lumbosacral Radiculopathy

Objective

To observe the contrast spread in superoposterior transforaminal epidural steroid injection (SP TFESI) and investigate the correlation between spread patterns and efficacy.

Methods

Thirty-one patients with lumbosacral radiculopathy underwent single-level TFESI under fluoroscopy. The final needle tip position was targeted toward the SP quadrant of the intervertebral foramen. To observe the spread, 1 mL of contrast material was injected, followed by a steroid injection. The contrast spread was graded anteroposteriorly and vertically in the epidural space. The effect of SP TFESI was evaluated by proportional pain score reduction.

Results

Levels injected were L4-5 (n=20) and L5-S1 (n=11). Seventeen cases were lateral, and 14 were central herniated disc (HD). Baseline mean visual analog scale score was 6.23. Contrast dispersed dorsally in all the cases, and 45.2% cases showed a concurrent ventral spread. The proportion of the pain reduction after 2 weeks showed no difference between the two groups. In vertical spreading analysis, mean cephalic/caudal grades were 1.40/1.55 at L4-5 level and 1.73/1.64 at L5-S1 level. The HD location had no effect on contrast dispersion.

Conclusion

In SP TFESI, ventral contrast spread did not guarantee a better effect; however, the extent of cephalic flow in ventral expansion group correlated with the proportion of pain reduction.

Surgical anatomy, radiological features, and molecular biology of the lumbar intervertebral discs

The intervertebral disc (IVD) is a joint unique in structure and functions. Lying between adjacent vertebrae, it provides both the primary support and the elasticity required for the spine to move stably. Various aspects of the IVD have long been studied by researchers seeking a better understanding of its dynamics, aging, and subsequent disorders. In this article, we review the surgical anatomy, imaging modalities, and molecular biology of the lumbar IVD. Clin. Anat. 30:251-266, 2017. © 2017 Wiley Periodicals, Inc.

Invagination of intra-abdominal structures in the lumbar intervertebral disc space

Invagination of peritoneal or retroperitoneal structures into the intervertebral disc space of the lumbar spine is extremely rare. In this article the imaging features and clinical findings are demonstrated in four patients with intervertebral invagination of intra-abdominal structures. Plain radiographs, CT scans, and MR images showed disruption of the anterior ligamentous complex (ALC) and invagination of various structures into the disc space, including the vena cava, iliac vessels, intestine, the torn redundant anterior longitudinal ligament, retroperitoneal fat, and the psoas muscle. The invaginations occurred at the level of L3-L4 and L4-L5 in one case each and at L5-S1 in two cases. Follow-up imaging in three cases (1, 5, and 8 years respectively) showed the progression of the invagination. These cases demonstrate that a close evaluation of this condition is necessary, particularly for older patients who show disruption or laxity of the ALC, degenerative spondylosis with chronic segmental instability, and osteoporosis of the lower lumbar spine.

Low intensity laser and LED therapies associated with lateral decubitus position and flexion exercises of the lower limbs in patients with lumbar disk herniation: clinical randomized trial

The objective of this study is to evaluate the effectiveness of laser and LED therapies, associated with lateral decubitus position and flexion exercises of the lower limbs in patients with lumbar disk herniation (LDH). It is a randomized blinded clinical trial. Fifty-four subjects with LDH L4-L5 and L5-S1 were selected and randomly allocated into groups: laser 904 nm, placebo, and LED 945 nm. The numbers of subjects for each group that completed the treatment were 18, 13, and 18, respectively. Twelve points over the lumbar spine region (L2 to S1) and eight points on the injured thigh in the path of the lumbar roots L5 and S1 were irradiated. Irradiation parameters for each point were as follows: laser wavelength 904 ± 10 nm, average power 0.038 ± 20 % W, irradiated area 0.16 cm(2), energy per point 4 J, and treatment time per point 104 s; LED wavelength 945 ± 15 nm, power 0.1 W, irradiated area 1.0cm(2), energy per point 4 J, and treatment time per point 40 s. Lateral decubitus opposite to the side of the radicular was the standard position for all patients. After phototherapy and laser placebo sessions, the subjects performed sequences of flexion exercises of the lower limbs (ten per session) for 15 daily sessions.

VARIABLES STUDIED

pain intensity assessed by visual analog scale (VAS), degree of flexion of the affected hip measured by the universal goniometer and functional capacity assessed by the Oswestry Disability Index. The three groups had statistically significant improvement in lumbar and radicular pain, in hip mobility, and in the functional disability index (p ≤ 0.001). There was a statistically significant difference (p = 0.024) in radicular pain between the groups, gait claudication and Oswestry Disability Index. We can conclude that in the treatment of L4-L5 and L5-S1 LDH with radiculopathy, LED, associated with lateral decubitus position and flexion exercises of the lower limbs, showed better therapeutic performance for radicular pain, gait claudication, and functional disability.

Airway management of patients with traumatic brain injury/C-spine injury

Traumatic brain injury (TBI) is usually combined with cervical spine (C-spine) injury. The possibility of C-spine injury is always considered when performing endotracheal intubation in these patients. Rapid sequence intubation is recommended with adequate sedative or analgesics and a muscle relaxant to prevent an increase in intracranial pressure during intubation in TBI patients. Normocapnia and mild hyperoxemia should be maintained to prevent secondary brain injury. The manual-in-line-stabilization (MILS) technique effectively lessens C-spine movement during intubation. However, the MILS technique can reduce mouth opening and lead to a poor laryngoscopic view. The newly introduced video laryngoscope can manage these problems. The AirWay Scope® (AWS) and AirTraq laryngoscope decreased the extension movement of C-spines at the occiput-C1 and C2-C4 levels, improving intubation conditions and shortening the time to complete tracheal intubation compared with a direct laryngoscope. The Glidescope® also decreased cervical movement in the C2-C5 levels during intubation and improved vocal cord visualization, but a longer duration was required to complete intubation compared with other devices. A lightwand also reduced cervical motion across all segments. A fiberoptic bronchoscope-guided nasal intubation is the best method to reduce cervical movement, but a skilled operator is required. In conclusion, a video laryngoscope assists airway management in TBI patients with C-spine injury.

Foxa1 and Foxa2 are required for formation of the intervertebral discs

The intervertebral disc (IVD) is composed of 3 main structures, the collagenous annulus fibrosus (AF), which surrounds the gel-like nucleus pulposus (NP), and hyaline cartilage endplates, which are attached to the vertebral bodies. An IVD is located between each vertebral body. Degeneration of the IVD is thought to be a major cause of back pain, a potentially chronic condition for which there exist few effective treatments. The NP forms from the embryonic notochord. Foxa1 and Foxa2, transcription factors in the forkhead box family, are expressed early during notochord development. However, embryonic lethality and the absence of the notochord in Foxa2 null mice have precluded the study of potential roles these genes may play during IVD formation. Using a conditional Foxa2 allele in conjunction with a tamoxifen-inducible Cre allele (ShhcreER^T2), we removed Foxa2 from the notochord of E7.5 mice null for Foxa1. Foxa1^−/−;Foxa2^c/c;ShhcreER^T2 double mutant animals had a severely deformed nucleus pulposus, an increase in cell death in the tail, decreased hedgehog signaling, defects in the notochord sheath, and aberrant dorsal-ventral patterning of the neural tube. Embryos lacking only Foxa1 or Foxa2 from the notochord were indistinguishable from control animals, demonstrating a functional redundancy for these genes in IVD formation. In addition, we provide in vivo genetic evidence that Foxa genes are required for activation of Shh in the notochord.

Nuclei pulposi formation from the embryonic notochord occurs normally in GDF-5-deficient mice

STUDY DESIGN

The transition of the mouse embryonic notochord into nuclei pulposi was determined ("fate mapped") in vivo in growth and differentiating factor-5 (GDF-5)-null mice using the Shhcre and R26R alleles.

OBJECTIVE

To determine whether abnormal nuclei pulposi formation from the embryonic notochord was responsible for defects present in adult nuclei pulposi of Gdf-5-null mice.

SUMMARY OF BACKGROUND DATA

The development, maintenance, and degeneration of the intervertebral disc are not understood. Previously, we demonstrated that all cells in the adult nucleus pulposus of normal mice are derived from the embryonic notochord. Gdf-5-null mice have been reported to contain intervertebral discs in which the nucleus pulposus is abnormal. It is currently unclear if disc defects in Gdf-5-null mice arise during the formation of nuclei pulposi from the notochord during embryogenesis or result from progressive postnatal degeneration of nuclei pulposi.

METHODS

Gdf-5 messenger RNA expression was examined in the discs of wild-type embryos by RNA in situ hybridization to determine when and where this gene was expressed. To examine nucleus pulposus formation in Gdf-5-null mice, intervertebral discs in which embryonic notochord cells were marked were analyzed in newborn and 24-week-old mice.

RESULTS

Our Gdf-5 messenger RNA in situ experiments determined that this gene is localized to the annulus fibrosus and not the nucleus pulposus in mouse embryos. Notochord fate-mapping experiments revealed that notochord cells in Gdf-5-null mice correctly form nuclei pulposi.

CONCLUSION

Our data suggest that the defects reported in the nucleus pulposus of adult Gdf-5-null mice do not result from abnormal patterning of the embryonic notochord. The use of mouse alleles to mark cells that produce all cell types that reside in the adult nucleus pulposus will allow for a detailed examination of disc formation in other mouse mutants that have been reported to contain disc defects.

Yoga and disc degenerative disease in cervical and lumbar spine: an MR imaging-based case control study

The objective of the current study was to find out whether yoga practice was beneficial to the spine by comparing degenerative disc disease in the spines of long-time yoga practitioners and non-yoga practicing controls, using an objective measurement tool, magnetic resonance imaging. This matched case-control study comprised 18 yoga instructors with teaching experience of more than 10 years and 18 non-yoga practicing asymptomatic individuals randomly selected from a health checkup database. A validated grading scale was used to grade the condition of cervical and lumbar discs seen in magnetic resonance imaging of the spine, and the resulting data analyzed statistically. The mean number of years of yoga practice for the yoga group was 12.9 ± 7.5. The overall (cervical + lumbar) disc scores of the yoga group were significantly lower (indicating less degenerative disc disease) than those of the control group (P < 0.001). The scores for the cervical vertebral discs of the yoga group were also significantly lower than those of the control group (P < 0.001), while the lower scores for the yoga group in the lumbar group approached, but did not reach, statistical significance (P = 0.055). The scores for individual discs of yoga practitioners showed significantly less degenerative disease at three disc levels, C3/C4, L2/L3 and L3/L4 (P < 0.05). Magnetic resonance imaging showed that the group of long-term practitioners of yoga studied had significantly less degenerative disc disease than a matched control group.

Low back pain

General internists and family practitioners play an important role in the initial evaluation and treatment of acute low back pain and chronic low back pain. Given the usual time constraints placed on the primary care physician for evaluation of a patient with back pain, it is imperative that the generalist be acquainted and comfortable with the salient points in the history, the essentials of the examination, the appropriate use of diagnostic tests, and the effectiveness (or lack thereof) of available treatments.