MR epidurography: distribution of injectate at caudal epidural injection.

OBJECTIVE: To (a) evaluate the feasibility of MR epidurography (MRE) and (b) assess the distribution of injectate using two different volumes at caudal epidural steroid injection. MATERIALS AND METHODS: Twenty patients who were referred with symptomatic low back pain for caudal epidural steroid injection were assigned to have either 10 ml (9/20) or 20 ml (11/20) of injectate administered. Gadolinium was included in the injection. The patients proceeded to MRI where sagittal and coronal T1-weighted fat-saturated sequences were acquired and reviewed in the mid-sagittal and right and left parasagittal views at the level of the exit foramina. RESULTS: Gadolinium was observed at or above the L3/4 disc level in all 11 patients who received 20 ml (100 %), compared with only five of nine patients who received 10 ml (56 %). Injectate was seen to the L4 nerve root level in all 11 patients who received 20 ml (100 %) but only four out of nine patients who received 10 ml (44 %), not even reaching the L5 nerve root level in four further of these nine patients (44 %). Overall, there was a trend to visualize gadolinium at higher levels of the epidural space with higher volumes injected. CONCLUSIONS: Firstly, MR epidurography is a safe technique that allows excellent visualization of the distribution of gadolinium in the epidural space following injection via the caudal hiatus. Secondly, a volume of 10 ml is unlikely to treat L5/S1 disease in almost half of patients at caudal epidural steroid injection and at least 20 ml of injectate is likely required for any medication to reach the desired level.

Acute nontraumatic spinal intradural hematoma in a patient on warfarin.

BACKGROUND: Nontraumatic spinal intradural extramedullary hematomas are extremely rare. When they occur, they can rapidly lead to spinal cord or cauda equina compression and have devastating consequences. OBJECTIVE: The aim here was to report a case of this rare phenomenon and discuss the etiology, imaging, management, and outcome of intradural hematomas. CASE REPORT: We describe the case of a 76-year-old man on warfarin therapy who presented with severe lower back pain and flaccid paraparesis. Blood tests revealed an international normalized ratio of 6.0. A magnetic resonance imaging result suggested an intradural hematoma extending from L1 to L4 and compressing the spinal cord and cauda equina. Emergency surgical decompression revealed an extensive intradural extramedullary hematoma, which was evacuated. The patient showed only minor neurologic improvement 6 months postoperatively. CONCLUSIONS: Coagulopathy-induced spinal hemorrhage should be included in the differential diagnosis for patients presenting with signs of acute spinal cord compression.

RhBMP-2 use in lumbar fusion surgery is associated with transient immediate post-operative leg pain.

PURPOSE: Supra-physiological rhBMP loads during spinal fusion may trigger local inflammation and post-operative radiculitis. MRI is an effective tool to detect nerve root compression in severe post-operative leg pain. The aim of this study was to determine if recombinant bone morphogenic protein 2 (rhBMP-2) is associated with immediate post-operative leg pain without evidence of root compression using MRI. METHOD: All patients undergoing posterolateral and posterior interbody lumbar spinal fusions with rhBMP-2 between July 2007 and January 2009 at a single surgeon practice were retrospectively reviewed for incidence of severe immediate post-operative leg pain. Patients that presented with immediate post-operative leg pain were interviewed and Oswestry Disability Indices calculated. RESULTS: Sixty-four rhBMP-2 treated patients and 40 controls were included. Pre-operative demographics and diagnoses were similar and inter-body cages were used equally. Immediate post-operative leg pain incidence was 25 and 12.5% in the rhBMP-2 and non-rhBMP-2 groups, respectively. 17.2% of the patients treated with rhBMP-2 had immediate post-operative leg pain without evidence of nerve root compression on MRI versus 7.5% of the patients treated without rhBMP-2. At follow-up, leg pain incidence was 11.6 and 7.6% in rhBMP-2 and non-rhBMP-2 groups, respectively. There was no difference in Oswestry Disability Indices between groups (36.5 ± 31.2 vs. 23.0 ± 25.5). CONCLUSION: RhBMP-2 associated radiculitis presenting as immediate post-operative leg pain without MRI evidence of neuronal compression occurs in 17% of the patients with rhBMP-2 assisted fusion. Patients should be pre-operatively counselled regarding immediate post-operative leg pain with rhBMP-2. LEVEL OF EVIDENCE: III.

Risk analysis of blood transfusion requirements in emergency and elective spinal surgery.

Spinal surgery has long been considered to have an elevated risk of perioperative blood loss with significant associated blood transfusion requirements. However, a great variability exists in the blood loss and transfusion requirements of differing patients and differing procedures in the area of spinal surgery. We performed a retrospective study of all patients undergoing spinal surgery who required a transfusion≥1 U of red blood cells (RBC) at the National Spinal Injuries Unit (NSIU) at the Mater Misericordiae University Hospital over a 10-year period. The purpose of this study was to identify risk factors associated with significant perioperative transfusion allowing the early recognition of patients at greatest risk, and to improve existing transfusion practices allowing safer, more appropriate blood product allocation. 1,596 surgical procedures were performed at the NSIU over a 10-year period. 25.9% (414/1,596) of these cases required a blood transfusion (n=414). Surgical groups with a significant risk of requiring a transfusion>2 U RBC included deformity surgery (RR=3.351, 95% CI 1.123-10.006, p=0.03), tumor surgery (RR=3.298, 95% CI 1.078-10.089, p=0.036), and trauma surgery (RR=2.444, 95% CI 1.183-5.050, p=0.036). Multivariable logistic regression analysis identified multilevel surgery (>3 levels) as a significant risk of requiring a transfusion>2 U RBC (RR=4.682, 95% CI 2.654-8.261, p<0.0001). Several risk factors in the spinal surgery patient were identified as corresponding to significant transfusion requirements. A greater awareness of the risk factors associated with transfusion is required in order to optimize patient management.

The meniscofemoral ligaments influence lateral meniscal motion at the human knee joint.

PURPOSE: The purpose of this study was to investigate the effect of the meniscofemoral ligaments on lateral meniscal motion during flexion and extension of the human knee joint. METHODS: A cadaveric biomechanical study was performed. The effect of meniscofemoral ligament tension on the dynamics of the posterior horn of the lateral meniscus was determined by image analysis. RESULTS: We found that the meniscofemoral ligaments functioned in a reciprocal manner, with the anterior meniscofemoral ligament developing tension with flexion and the posterior meniscofemoral ligament tensioning with extension. Analysis of posterior horn motion showed that the meniscofemoral ligaments caused a medial, superior, and anterior displacement of the posterior horn throughout knee motion, thus increasing the congruity of the posterior meniscal arch and the lateral femoral condyle. There was a significant correlation between meniscofemoral ligament tension and displacement of the posterior meniscal horn (r = 0.76, P < .0001). CONCLUSIONS: Where both meniscofemoral ligaments were present, the posterior horn of the lateral meniscus was subject to a displacing force throughout the range of knee motion tested. The degree of displacement correlated with the magnitude of ligament tension, and its direction was anteromedial and superior. CLINICAL RELEVANCE: The findings of this study provide further information on the role of the meniscofemoral ligaments at the human knee joint and may influence decisions regarding the management of ligamentous or lateral meniscal injury.

Prevalence of Internet use amongst an elective spinal surgery outpatient population.

Nationally 62% of individuals in Ireland have internet access. Previous published work has suggested that internet use is higher among those with low back pain. We aimed to determine the levels of internet access and use amongst an elective spinal outpatient population and determine what characteristics influence these. We distributed a self-designed questionnaire to patients attending elective spinal outpatient clinics. Data including demographics, history of surgery, number of visits, level of satisfaction with previous consultations, access to the internet, possession of health insurance, and details regarding use of the internet to research one's spinal complaint were collected. 213 patients completed the questionnaire. 159 (75%) had access to the internet. Of this group 48 (23%) used the internet to research their spinal condition. Increasing age, higher education level, and possession of health insurance were all significantly associated with access to the internet (p < 0.05). A higher education level predicted greater internet use while possession of insurance weakly predicted non-use (p < 0.05). In our practice, internet access is consistent with national statistics and use is comparable to previous reports. Approximately, one quarter of outpatients will use the internet to research their spinal condition. Should we use this medium to disseminate information we need to be aware some groups may not have access.

Central cord syndrome in Ireland: the effect of age on clinical outcome.

Central cord syndrome is an incomplete spinal cord injury first described by Schneider et al. (J Neurosurg 11:546-547, 1954). The typical neurological deficit is symmetrical incomplete quadriplegia affecting the upper more than the lower limbs; sensory impairment is variable and urinary retention is common. Records of all patients with acute traumatic central cord syndrome admitted to the National Spinal Injuries Unit from 1999 to 2007 were compiled from a prospectively collected computerized spinal database. Data recorded included patient demographic profile, mechanism of injury, initial neurological deficit, treatment instituted, complications of treatment, and final neurological status. A total of 50 patients with acute traumatic central cord syndrome were identified accounting for 6.2% of all admissions to the spinal injuries unit. There were 42 men and 8 women. The mean age was 56.1 years with a range of 41-88 years. We stratified patients according to age at injury to determine the effect of age on clinical outcome. There were 13 patients <50 years of age, 24 aged 50-70, and 13 aged >70 years. The mean follow-up time was 42.2 months. More than one-third of patients were intoxicated with alcohol at the time of the injury. Both upper and lower limb motor scores and total sensory scores improved in all age groups. Absolute and relative improvements were greatest in patients <50 years of age. Sphincter disturbance was documented in 42% of all the patients on admission. At follow up 12% of patients had residual disturbance. At final follow up none of the patients under 70 years of age had residual sphincter disturbance while 60% of those aged >70 years group had. Both of these results reached statistical significance. In conclusion, central cord syndrome is a common cause of acute traumatic neurological deficit, with alcohol intoxication being a common confounder at the time of injury. The clinical outcomes are significantly worse in patients aged 70 years or older.

Analysis of meniscofemoral ligament tension during knee motion.

PURPOSE: The goal of this study was to show a functional role for the meniscofemoral ligaments (MFL) by analyzing MFL tension change through the full range of flexion and extension found at the human knee joint. METHODS: Ten fresh-frozen human knees containing both the anterior and posterior MFLs (aMFL and pMFL) were studied. An analysis of ligament tension during passive motion was undertaken using an isometric transducer. RESULTS: The MFLs functioned in a nonisometric and reciprocal manner. The aMFL developed tension with flexion and the pMFL tension with extension. The aMFL tension increased with tibial external rotation compared with internal rotation. Combined MFL tension was greater in flexion (P < .001) and increased as the tibia was externally rotated (P = .008). CONCLUSIONS: The MFL tension changes identified through knee flexion and extension support the theory that the MFLs have a functional role in knee stability and protection. This warrants their consideration in the clinical management of meniscal and PCL injuries. CLINICAL RELEVANCE: This cadaver study of the lateral MFLs indicates that the anterior and posterior portions work in a reciprocal manner with flexion and extension and supports the fact that these ligaments have a functional role in the human knee joint.

Mechanical and cellular processes driving cervical myelopathy.

Cervical myelopathy is a well-described clinical syndrome that may evolve from a combination of etiological mechanisms. It is traditionally classified by cervical spinal cord and/or nerve root compression which varies in severity and number of levels involved. The vast array of clinical manifestations of cervical myelopathy cannot fully be explained by the simple concept that a narrowed spinal canal causes compression of the cord, local tissue ischemia, injury and neurological impairment. Despite advances in surgical technology and treatment innovations, there are limited neuro-protective treatments for cervical myelopathy, which reflects an incomplete understanding of the pathophysiological processes involved in this disease. The aim of this review is to provide a comprehensive overview of the key pathophysiological processes at play in the development of cervical myelopathy.

Resorbable posterolateral graft containment in a rabbit spinal fusion model.

OBJECT: The authors studied the effect of a resorbable graft containment device in a rabbit posterolateral lumbar spinal fusion model. METHODS: Twenty rabbits were divided into four groups: autologous bone graft (ABG), ABG with the MacroPore containment device (ABG + MP), demineralized bone matrix (DBM), and DBM with the containment device (DBM + MP). Fusion mass was assessed at 6 weeks with high-resolution radiography and volumetric computerized tomography. The graft containment device was associated with alteration of the fusion mass structure and significant enhancement of fusion mass volume (ABG versus ABG + MP, p = 0.027; DBM versus DBM + MP, p = 0.043). CONCLUSIONS: A bioabsorbable protective graft containment device successfully enhanced posterolateral spinal fusion mass volume.

Orthopedic management of vertebral and long bone fractures in patients with osteoporosis.

Because of the evolving demographics of the world's population, fracture surgeons must become experts in the treatment of fractures in osteoporotic bone. Toward this end, fracture surgeons are learning to modify the classic techniques of internal fixation to adapt them to the elderly population. Screws should be placed into the best quality of bone available, which, in most cases, is an opposing cortex. Screw fixation can be augmented using acrylic cement. When using plate fixation, stable bone contact at the fracture site is the most important factor in reducing strain in the plate. Shortening of the affected bone is advisable to achieve this contact in comminuted fractures. Plates should not be used to bridge areas of comminution in osteoporotic bone. Plates should generally be as long as is compatible with the affected bone, with screws placed as close to and as far away from the fracture site as possible. When confronted with diaphyseal fractures or fractures with metaphyseal-diaphyseal comminution, locked intramedullary nails can be used. Angled blade plates are applicable to osteoporotic metaphyseal fractures but should be used as tension band plates, which require stable load-sharing contact opposite the plate. Antiglide plating and use of tension band wires are also effective strategies for osteoporotic fractures. Finally, to reduce the morbidity of bone graft harvest and to ensure adequate volumes of graft, the use of bone graft substitutes is particularly applicable in elderly patients. All patients with evidence of osteoporosis should be started on a medical regimen to combat further bone loss that includes calcium supplementation with a prescription for antiresorptive agents, including bisphosphonates, calcitonin, or hormone replacement therapy.

Medical management of osteoporosis.

Osteoporosis is characterized by low-energy fractures resulting from inadequate bone mass and compromised microarchicture. Bone mass is maximized by adequate nutrition and calcium intake, normal menstrual cycles, and appropriate exercises. Low bone density, as determined by dual-energy x-ray absorptiometry, and high bone turnover, as characterized by elevated bone collagen breakdown products, are the primary indicators of bone fragility. Prevention and treatment of osteoporosis should emphasize adequate calcium and vitamin D intake and exercise. In addition, estrogen supplementation and selective estrogen receptor modulators (estrogen antagonists) can enhance bone mass and decrease the risk of spinal fractures, oral and intravenous bisphosphonates can significantly decrease the incidence of both spinal and hip fractures, and antiosteoporotic agents can help rebuild healthy bone.

Resorbable posterolateral graft containment in a rabbit spinal fusion model.

The effect of a resorbable graft containment device was evaluated in a rabbit posterolateral lumbar spinal fusion model. Twenty rabbits were divided into four groups: autogenous bone graft (ABG), ABG with the MacroPore containment device (MacroPore Biosurgery Inc, San Diego, Calif) (ABG+MP), demineralized bone matrix (DBM), and DBM with the containment device (DBM+MP). Fusion mass was assessed at 6 weeks with high resolution radiographs and volumetric computed tomography (CT). The graft containment device was associated with alteration of the fusion mass structure and significant enhancement of fusion mass volume (ABG versus ABG+MP, P=.027; DBM versus DBM+MP, P=.043). A bioabsorbable, protective graft containment device successfully enhanced posterolateral spinal fusion mass volume.

Nonoperative modalities to treat symptomatic cervical spondylosis.

Cervical spondylosis is a common and disabling condition. It is generally felt that the initial management should be nonoperative, and these modalities include physiotherapy, analgesia and selective nerve root injections. Surgery should be reserved for moderate to severe myelopathy patients who have failed a period of conservative treatment and patients whose symptoms are not adequately controlled by nonoperative means. A review of the literature supporting various modalities of conservative management is presented, and it is concluded that although effective, nonoperative treatment is labour intensive, requiring regular review and careful selection of medications and physical therapy on a case by case basis.

The natural history and clinical syndromes of degenerative cervical spondylosis.

Cervical spondylosis is a broad term which describes the age related chronic disc degeneration, which can also affect the cervical vertebrae, the facet and other joints and their associated soft tissue supports. Evidence of spondylitic change is frequently found in many asymptomatic adults. Radiculopathy is a result of intervertebral foramina narrowing. Narrowing of the spinal canal can result in spinal cord compression, ultimately resulting in cervical spondylosis myelopathy. This review article examines the current literature in relation to the cervical spondylosis and describes the three clinical syndromes of axial neck pain, cervical radiculopathy and cervical myelopathy.

Cervical laminoplasty for multilevel cervical myelopathy.

Cervical spondylotic myelopathy can result from degenerative cervical spondylosis, herniated disk material, osteophytes, redundant ligamentum flavum, or ossification of the posterior longitudinal ligament. Surgical intervention for multi-level myelopathy aims to decompress the spinal cord and maintain stability of the cervical spine. Laminoplasty was major surgical advancement as laminectomy resulted in kyphosis and unsatisfactory outcomes. Hirabayashi popularised the expansive open door laminoplasty which was later modified several surgeons. Laminoplasty has changed the way surgeons approach multilevel cervical spondylotic myelopathy.

The evaluation of the inverted supinator reflex in asymptomatic patients.

STUDY DESIGN: A prospective study was undertaken over a 6-month period to determine the incidence of the inverted supinator reflex in asymptomatic, neurologically normal individuals. OBJECTIVE: The objective of our study is to assess asymptomatic patients for the presence of the inverted radial reflex and to determine its clinical relevance. SUMMARY OF BACKGROUND DATA: The inverted radial reflex sign is commonly used in clinical practice to assess cervical myelopathy. It is unknown whether the sign correlates with the presence or severity of myelopathy, and no consensus exists regarding the significance of a positive sign in asymptomatic individuals. METHODS: Patients attending the Trauma Clinic at our institution were invited to participate. Each patient was examined neurologically and specifically for the presence or absence of the Babinski test, Hoffman's sign, the finger escape sign, static and dynamic Romberg's test, and the inverted supinator reflex. Patients were excluded if they had any history of neck pain, any history of neurosurgical procedure or spinal surgery, any known neurologic disorder or deficit, or if there was any outstanding medicolegal case. RESULTS: We examined 277 patients in 6-month period. The male to female ratio was 1.1:1. The mean age was 27 years (range, 16-78). The incidence of the inverted supinator reflex was 27.6% (75/271). Of the 75 positive patients, the inverted supinator reflex was present bilaterally in 39% (29/75). Nine of 75 patients (10%) had an associated positive Hoffman's sign but had no other signs suggestive of myelopathy. The proportion of patients with a positive inverted supinator reflex reduced with increasing age (Pearson correlation coefficient > 0.80). CONCLUSION: This study demonstrates that an isolated, inverted supinator reflex may be a variation of normal clinical examination. We believe that an isolated inverted supinator reflex, in the absence of other clinical findings, is not a reliable sign of cervical myelopathy; however, it must be interpreted with caution in the older patient.

Parathyroid hormone (1-34) augments spinal fusion, fusion mass volume, and fusion mass quality in a rabbit spinal fusion model.

STUDY DESIGN: The posterolateral rabbit spinal fusion model was used to assess the effect of intermittent parathyroid hormone on spinal fusion outcomes. OBJECTIVE: To test the hypothesis that intermittent parathyroid hormone (PTH) improves spinal fusion outcomes in the rabbit posterolateral spinal fusion model. SUMMARY OF BACKGROUND DATA: Spinal fusion is the definitive management for spinal deformity or instability, yet despite current technology, 5% to 40% of lumbar fusions result in pseudarthrosis. Animal studies have demonstrated enhanced fracture healing with the use of PTH, but the effect of PTH on spinal fusion is poorly described. METHODS: Forty-four male New Zealand white rabbits underwent bilateral posterolateral spine fusion (L5-L6 level). Twenty-two rabbits received daily subcutaneous injections of PTH (1-34) (10 microg/kg) and 22 received an injection of saline fluid. All were killed 6 weeks after surgery. L5-L6 vertebral segments were removed and analyzed with manual bending, faxitron radiography, microCT, and histomorphometry. RESULTS: Manual bending identified fusion in 30% (control) versus 81% (PTH) animals (P < 0.001). A radiographic scoring system ("0" = no bone formation, "5" = full fusion) resulted in an average score of 3.36 (control) versus 4.51 (PTH) (P < 0.001). MicroCT analysis demonstrated a median mass of 3.5 cc (control) (range, 2.25-5.40 cc) versus 6.03 cc (PTH) (range, 4.34-10.58 cc) (P < 0.001). Histology showed a median percentage bone area of 14.3% (control) (n = 12) versus 29.9% (PTH) (n = 15) (P < 0.001). The median percentage cartilage was 2.7% (control) (n = 5) versus 26.6% (PTH) (n = 5) (P < 0.01). Osteoclast quantification revealed median values of 140.5 (control) (n = 6) and 345.0 (PTH) (n = 8) (P < 0.001) respectively, and the percentage of osteoblasts revealed a median value of 31.4% (control) (n = 6) versus 64.4% (PTH) (n = 8) (P < 0.001). CONCLUSION: Intermittent PTH administration increased posterolateral fusion success in rabbits. Fusion bone mass and histologic determinants were also improved with PTH treatment. PTH has promise for use as an adjunctive agent to improve spinal fusion in clinical medicine.