Traumatic instability of the lumbar spine. A dynamic in vitro study of flexion-distraction injury

STUDY DESIGN: This in vitro study determined the effect on the lumbar spine of a dynamic flexion-distraction loading simulating a lap seatbelt injury. The proportion by which the forces and the moments contributed to the injury of the lumbar spinal segment in such a situation was analyzed. The remaining stability of the injured lumbar motion segment was determined together with the threshold for lumbar spine instability in such an injury. OBJECTIVES: Based on the experimental results in this study, radiographic guidelines for instability criteria in lumbar and thoracolumbar dislocations in the sagittal plane without concomitant compression fracture of the middle column were proposed. SUMMARY OF BACKGROUND DATA: A number of check-lists and guidelines were suggested for the diagnosis of spinal instability after trauma, but no conclusive system was established. Those systems were mostly based on experiments performed on spinal segments after sequential ablation of ligaments and facet joints followed by static, unidirectional physiologic loading. We believed that there was a need for more profound knowledge of spinal injury and for instability criteria of lumbar spinal injuries based on more realistic experimental data simulating the clinical situation. In our injury model, we decided to study the biomechanic outcome of a flexion-distraction injury similar to seatbelt type injury seen in frontal motor vehicle collisions. METHODS: Twenty lumbar functional spinal units were first loaded statically with a physiologic flexion-shear load to determine angulations and displacements under noninjurous conditions. Dynamic flexion-shear loading to injury with two different load pulses was then applied. Static physiologic load was then again applied to determine any permanent residual deformation. RESULTS: The viscoelastic effect of loading rate on translatory and angular displacements and the values for translatory and angulation displacements at first sign of injury (yield) and at failure were determined. CONCLUSIONS: Radiographic guidelines for instability criteria in lumbar and thoracolumbar fracture-dislocations without concomitant posterior vertebral body compression are proposed: 1. Instability exists if there is a kyphosis of the lumbar motion segment > or = 12 degrees (impending instability) or > or = 19 degrees (total instability) on lateral radiographs. 2. Relative increase in interspinous process distance > or = 20 mm (impending instability), > or = 33 mm (total instability) on anteroposterior radiographs.     

Anatomy of the lumbar spine

The macroscopic courses of the posterior primary rami in the lumbar spine are described and illustrated from fresh cadaver dissections.     

Giant-cell tumour of the lumbar spine. Case report

Giant-cell tumours of the spine are very rare. They occur mainly in long bones. We report a patient with a giant-cell tumour of the lumbar spine which had been operated on at another hospital 5 months previously as a protruded lumbar intervertebral disc.     

Physical measurements of the lumbar spine

This article describes measurement of lumbar function. The simplest range of motion devices are compared with the progressive, more complex computerized devices for range and strength testing. The author presents his own opinion as to the place of these devices in both research and clinical practices. The economics of accurate physical testing is compared to the clinical realities of current payment systems.     

Pseudarthrosis of the lumbar spine. Outcome after circumferential fusion

STUDY DESIGN: Twenty-five patients with a pseudarthrosis after previous spinal fusion surgery were reviewed after a circumferential fusion was performed. OBJECTIVES: To determine the fusion rate and its relation to outcome, i.e., pain reduction and return to work, and associated complications. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure with more patients undergoing multiple operations. This operation is thought to improve the fusion rate with a low complication rate. However, the procedure has not been evaluated specifically for the management of pseudarthrosis. METHODS: Twenty-five patients were reviewed regarding age, gender, smoking status, previous back surgeries, extent of leg and back pain, occupation, levels of surgery, type of instrumentation, blood loss, and complications. A minimum follow-up period of 2 years included evaluation of radiographs, pain levels, medication, and return to work. RESULTS: Twenty percent of patients were heavy smokers. An average of 2.2 previous procedures had been performed, and the average follow-up period was 2.7 years. Eighty percent of patients underwent multiple-level fusions. A solid fusion was achieved in 100%. Complications included two painful instrumentation devices requiring removal, one retroperitoneal hematoma, one anterior abdominal wall dehiscence, and one case of pneumonia. Pain scores improved from 7.4 to 4.7 for back pain, and 5.4 to 2.8 for leg pain, respectively. Both improvements were statistically significant (P < 0.01 and 0.003, respectively). However, only 52% of patients reduced their pain by a full category. Forty-one percent were still taking narcotics intermittently or consistently, and 53% returned to work or were actively seeking employment. DISCUSSION: A fusion rate of 100% was noted in the face of factors often placing patients at high risk for developing a pseudarthrosis, namely multiple levels of previous spinal surgery, including previous pseudarthrosis, and a habit of heavy smoking. Complications were few. However, the satisfactory outcome rate was only somewhat better than 50%, based on a lack of substantial pain improvement and return to work.     

Vascular injury during lumbar disc surgery. Report of two cases; a review of the literature

Iatrogenic vascular injuries are unusual complications of lumbar disc surgery. The incidence of such injuries is very low but probably underestimated because clinical manifestations may be extremely variable depending on the extension of trauma. Diagnosis is suspected when early signs of retroperitoneal haemorrhage appear, but may often be delayed for weeks or years due to formation of a pseudoaneurysm or an arteriovenous fistula which may be of gradual onset and produce initially only a few symptoms. Prompt diagnosis and aggressive treatment can improve the current mortality rate of more than 50%. Two cases are described that illustrate the full spectrum of acute and chronic manifestations of such injuries. One case of acute haemorrhage due to arterial trauma was immediately detected and the other case with arteriovenous fistula was recognized several years post-operatively.     

Minimally invasive anterior retroperitoneal approach to the lumbar spine. Emphasis on the lateral BAK

STUDY DESIGN: Eighteen patients with lumbar instability from fractures, postlaminectomy syndrome, or infection were treated prospectively with minimally invasive retroperitoneal lumbar fusions. OBJECTIVES: To determine if interbody Bagby and Kuslich fusion cages and femoral allograft bone dowels can be inserted in a transverse direction via a lateral endoscopic retroperitoneal approach to achieve spinal stability. SUMMARY OF BACKGROUND DATA: Endoscopic spinal approaches have been used to achieve lower lumbar fusion when instrumentation is placed through a laparoscopic, transperitoneal route. However, complications of using this approach include postoperative intra-abdominal adhesions, retrograde ejaculation, great vessel injury, and implant migration. This study is the first clinical series investigating the use of the lateral retroperitoneal minimally invasive approach for lumbar fusions from L1 to L5. METHODS: Eighteen patients underwent anterior interbody decompression and/or stabilization via endoscopic retroperitoneal approaches. In most cases, three 12-mm portals were used. Two parallel transverse interbody cages restored the neuroforaminal height and the desired amount of lumbar lordosis was achieved by inserting a larger anterior cage, distraction plug, or bone dowel. RESULTS: The overall morbidity of the procedure was lower than that associated with traditional "open" retroperitoneal or laparotomy techniques, with a mean length of hospital stay of 2.9 days (range, outpatient procedure to 5 days). The mean estimated intraoperative blood loss was 205 cc (range, 25-1000 cc). There were no cases of implant migration, significant subsidence, or pseudoarthrosis at mean follow-up examination of 24.3 months (range, 12-40 months) after surgery. CONCLUSIONS: This preliminary study of 18 patients illustrates that endoscopic techniques can be applied effectively through a retroperitoneal approach with the patient in the lateral position. Unlike the patients who had undergone transperitoneal procedures described in previous reports, in these preliminary 18 patients, there were no cases of retrograde ejaculation, injury to the great vessels, or implant migration.     

Adaptation of the lumbar spine to different positions in bicycle racing

STUDY DESIGN: A radiologic and electromyographic study was done of the adaptation of the lumbar spine to high-performance cycling. OBJECTIVES: To evaluate changes in the lumbar spine produced by different cycling positions on different types of bicycles used during competition. METHODS: Three professional cyclists were observed to evaluate changes in the lumbar spine. Radiographs were obtained of the different positions adopted by the cyclists during competition, and changes in the angles of the lumbar spine were measured. An electromyographic study was done of the abdominal, lumbar, and thoracic paravertebral muscles. RESULTS: The cyclists' positions involved a change from discal lordosis to kyphosis. To obtain a more aerodynamic position, the cyclists flexed the hip and made the pelvis horizontal without changing disc angles. The contraction of paravertebral lumbar muscles was proportional to pedalling intensity and decreased in more aerodynamic positions. The tone of the paravertebral thoracic muscles depended on the extent of cervical hyperextension. Abdominal muscles remained relaxed in all bicycle positions and with all pedalling intensities. CONCLUSIONS: The changes observed could modify the normal biomechanics of the lumbar spine, but the overall mechanical load on the spine is reduced by shifting weight onto the upper limbs. The imbalance that occurs between the activity of flexor and extensor muscles could cause lumbar pain in persons without proper physical preparation.     

Computer-assisted measurement of lumbar spine radiographs

RATIONALE AND OBJECTIVES: The authors evaluated a method for obtaining reproducible, reliable measurements from standard lumbar spine radiographs for determining the degree of spondylolisthesis, vertebral body height, intervertebral disk space height, disk space angle, and degree of vertebral body wedging. MATERIALS AND METHODS: Four to six easily defined points were identified on each vertebral body on anteroposterior and lateral plain radiographs of the lumbosacral spine of patients. From these points, the degree of spondylolisthesis, the vertebral body height, the intervertebral disk space height, the disk space angle, and the degree of vertebral body wedging were easily calculated by using well-known geometric relationships. This method requires the use of a personal computer and a standard spreadsheet program but does not require the use of any other specialized radiographic equipment, computer hardware, or custom software. RESULTS: Calculations of intra- and interobserver variability for the measurement of spondylolisthesis, disk space height, disk space angle, and vertebral body height measurement showed that the technique is extremely reproducible. CONCLUSION: This technique may prove useful in the prospective evaluation of potential candidates for lumbar spinal stenosis surgery.     

Postcatheterization retroperitoneal hematoma due to spontaneous lumbar arterial hemorrhage

Non-traumatic stereotyped postictal purpura is rare. A 25-year-old woman presented with right facial, cheek and periorbital purpuric eruptions that occurred after secondarily generalized tonic-clonic seizures. The stereotyped, invariably right-sided facial skin eruption, which resolved in 48 hours, falsely raised concerns of spousal abuse. Possible pathophysiological mechanisms include: (a) valsalva-induced capillary hypertension with secondary purpura, (b) ictal corticolimbic stimulation of the autonomic nervous innervation of facial vasomotor structures, and (c) trigeminal-mediated local release of vasoactive substances. Although rare, such stereotyped patterns of purpura should be recognized to avoid incorrect attribution of spousal abuse.     

Plans to resist distraction.

Conducted 2 experiments with a total of 71 preschoolers to investigate the effects of giving such Ss plans to resist distraction on their actual resistance in a subsequent work situation. A paradigm was developed in which the S, while motivated to work on a repetitive task, was exposed to a "Clown Box" which went through a standardized routine designed to distract the S from his work. The dependent variable assessed the amount of time the S worked in the E's absence. In Exp I, it was found, whether or not the Ss had rehearsed the actions called for in the plans, those who were given 3 plans for resistance worked longer than those who were not given plans. In Exp II it was found that Ss who were given only 1 plan worked as much as Ss who were given 3 plans, and more than Ss who were not given plans. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patient outcomes after reoperation on the lumbar spine

A prospective, randomized trial was conducted to compare the effectiveness and safety of warfarin given in two regimens in prevention of venous thrombosis after total knee replacement. Adult patients scheduled for primary or revision total knee replacement were randomly assigned to receive either a "two-step" warfarin regimen beginning 10-14 days pre-operatively or, alternatively, to begin warfarin the night before surgery. Post-operatively, the dose was adjusted in both groups to achieve a target International Normalized Ratio (INR) of 2.2 and prophylaxis was continued until venography on post-operative days five through nine. Bleeding was assessed by surgical blood loss, transfusion requirements, changes in hematocrit, and clinically identified bleeding complications. The occurrence of deep vein thrombosis was nearly the same in the two treatment groups, 39% in patients randomized to the two-step regimen as compared to 38% in those beginning the night before surgery. The occurrence of proximal vein thrombosis was also similar, 5% versus 7% (p = NS). Patients in the two-step group received 1.33 +/- 1.26 transfusions compared to 0.95 +/- 1.22 in the night before group (p < 0.05) and also had a lower nadir post-operative hematocrit of 26.7 +/- 3.1 as compared to 28.5 +/- 3.2 (p < 0.0001). Major bleeding complications were associated with excessively prolonged INRs and occurred in five patients in the two-step group and two in the night before group. Patients in both groups who developed thrombosis had a significantly lower INR on post-operative days two and three compared to those without thrombosis. We conclude that a prophylactic warfarin regimen for prevention of deep vein thrombosis after total knee replacement beginning the night before surgery is more convenient and may be associated with less bleeding than a regimen beginning warfarin 10-14 days pre-operatively. Careful control of anticoagulant intensity is needed to achieve maximum effectiveness and avoidance of bleeding complications.     

Causes of failure of surgery on the lumbar spine

An interinstitutional study on the failed back surgery syndrome (FBSS) has determined that failure to recognize or adequately treat lateral stenosis of the lumbar spine with resultant nerve irritation and/or compression comprised the primary etiology in 57% to 58% of patients. Other common causes were recurrent or persistent disk herniation and lumbosacral adhesive arachnoiditis. The diagnosis of stenosis was made either by high-resolution CT scan of the lumbar spine or by directly testing lateral canal and for animal patency at the time of surgery. It is now appreciated that the process of degenerative disk disease, particularly when enhanced by diskectomy, results in progressive loss of intervertebral disk volume and predisposes to future ipsilateral or contralateral lateral spinal stenosis. Degenerative disk disease is ultimately a bilateral process and therefore surgical exposure should be bilateral. The direct and indirect costs of FBSS to patients and to society as well as the toll in human suffering are very high. This is particularly a matter of concern when it is realized that for many FBSS patients, surgery could have been avoided in the first place by preventive care or by innovative conservative treatment. When surgery is indicated, adequate diagnostic tests and the execution of appropriate procedures based upon this information should largely prevent the failed back surgery syndrome.     

Physicians'' use of lumbar spine imaging tests

A bizarre case of a foreign-body bezoar is presented. A 16-year-old girl swallowed large amounts of toilet paper as a means of dieting. She presented with a palpable abdominal mass, multiple bezoars in the bowel, and paper excretion in the feces before admitting intentional ingestion of toilet-paper balls. Administration of Gastrografin via a nasogastric tube and enemas resulted in gradual excretion of the paper balls.     

Biomechanics of injury of the cervical spine

Whiplash injuries of the cervical spine are of special medical and socio-economic importance. Biomechanical studies of the injury have proven, that a hypertranslation of the capito-cervical region takes place first, leading to ligamentous hyperdistension and ruptures, when exceeding elastic deformation, thus possibly resulting in mechanical disturbance and rotatory malpositioning. Diagnosis of so called "functional disorders" bears difficulties concerning objective tests for structural lesions. This demands the definition of diagnostic parameters and clinical signs, which also consider vegetative phenomena. This paper aims at a systematic clinical and radiological check. Adequate therapeutic means have to be concordant to prognosis. Therefore functional parameters should already determine differential diagnosis. This is based on technical feasibilities and needs future scientific efforts.     

Nephrectomy through lumbar endoscopy. Report of 3 cases

The major outer surface protein, OspA, of Borrelia burgdorferi is a lipoprotein which is a particular interest because of its potential as a vaccine candidate. However, serotypic and genetic analysis of OspA from both European and North American strains have demonstrated antigenic and structural heterogeneities. We purified OspA to homogeneity by exploiting its resistance to trypsin digestion. By treating spirochetes with trypsin and then using Triton X-114 extraction and ion-exchange chromatography, we obtained a yield of 2 mg of pure OspA protein per liter of culture. INtrinsic labeling with [14C]palmitic acid confirmed that OspA was lipidated, and partial digestion established lipidation at the amino-terminal end of the molecule. The reactivity of five anti-OspA murine monoclonal antibodies to nine different isolates of B. burgdorferi was ascertained by Western blot (immunoblot) analysis. Purified OspA was fragmented by enzymatic or chemical cleavage, and the monoclonal antibodies were able to define four distinct immunogenic domains. Further resolution of the epitope specificity to determine humoral and cellular immune responses to OspA has implications for vaccine development and for the utility of this protein as a reagent in diagnostic testing for Lyme borreliosis.