Decompression and circumferential stabilization of unstable spinal fractures

A technique of anterior decompression of the spinal canal with anterior strut grafts, followed by posterior instrumentation and local fusion, is described in a group of 18 patients with unstable thoracolumbar fractures. All patients were found to have greater than 50% encroachment of the spinal canal and a preoperative kyphosis of 21.8 degrees. At follow-up 81% of patients with incomplete neurological lesions improved at least one Frankel Grade. Residual encroachment on the spinal canal was 4.6% and at follow-up the kyphotic angle was 17.1 degrees. Complications included one anterior graft loosening (not requiring revision), three loosened rods, only one of which required revision, and one fractured Harrington rod which did not require revision. The authors conclude that this technique is an effective and safe method for treating unstable thoracolumbar injuries and is recommended if anterior instrumentation is unavailable.

The neurological outcome following surgery for spinal fractures

Sixty consecutive patients with spinal injuries and encroachment upon the spinal canal of greater than 20% were assessed for neurological outcome. The patients were divided into two groups, those undergoing posterior surgery alone, and those undergoing anterior surgery for formal decompression with or without anterior or posterior instrumentation. In those patients undergoing posterior surgery, an improvement rate in the neurological function of 83% was noted in patients with incomplete lesions, whereas an 88% improvement rate was found in those undergoing the anterior procedure. There was no statistical difference in outcome between these two groups. Positive correlations were found between the level of injury and Frankel grades. The cord lesions tended to demonstrate more severe neurological deficit, whereas the cauda equina lesions were associated with a lesser severity of neurologic deficit. A component of dislocation to the injury also resulted in a more severe neurological deficit. There was no apparent difference between the degree of bony encroachment of the spinal canal and the initial Frankel grade, nor was there a clear difference between those patients undergoing anterior versus posterior surgery.

The effect of Harrington rod contouring on lumbar lordosis

The effect of Harrington rod sagittal plane contouring, or lack of it, on total lumbar, segmental lumbar, and lumbosacral lordosis was studied retrospectively in a series of 36 patients operated on for idiopathic scoliosis. Regardless of contouring, there was a decrease in total lumbar lordosis and lordosis above L4, with an increase in lordosis below L5. Although not statistically significant, patients with contoured rods had less loss of segmental (L1-4) lordosis and less increase in segmental lumbosacral lordosis (L4-S1) than the noncontoured group. Although helpful, additional steps beyond concave rod contouring appear to be necessary to consistently preserve lumbar lordosis.

Risk of iatrogenic septic arthritis in the presence of bacteremia: a rabbit study

This study of rabbits determined the risk of producing iatrogenic septic arthritis by arthrocentesis in the presence of bacteremia. In bacteremic animals, three of 20 knees became infected following joint aspiration, and six of 20 knees became infected on injection of 0.2 ml of bacteremic blood. Spontaneous joint sepsis did not develop, even in bacteremic animals. Prophylactic cefazolin before joint aspiration prevented the development of iatrogenic septic arthritis but did not prevent the recovery of bacteria from an infected joint. Therefore, there is an increased risk of development of joint sepsis in this animal model following a traumatic aspiration in the presence of bacteremia. This risk can be minimized by intravenous antibiotics without decreasing the likelihood of recovery of an organism if the joint is septic.

Strategies for prevention of byssinosis

Cotton dust is a heterogeneous mixture of plant parts and contaminants from the soil, weeds, and microorganisms. Research to control byssinosis has focused on methods to reduce the trash associated with harvested fiber and control the dust in the textile mill environment. Dust control has been effective in reducing the prevalence of byssinosis, but because cotton dust is a heterogeneous mixture of components, simple reduction in dust levels does not always assure the prevention of byssinosis. Research to identify the agents that cause byssinosis and development of methods to eliminate those agents from cotton is needed to prevent new cases of byssinosis.

Biomechanical studies of an anterior pelvic external fixation frame intended for control of vertical shear fractures

Biomechanical testing of an experimental pelvic external fixation frame incorporating a large tubular horizontal member was carried out on formalin-fixed cadaver pelves with simulated vertical shear injuries. The device was tested with 5 mm standard and 6 mm experimental pins, and was compared to a Pittsburgh triangular (PT) frame constructed of standard Hoffmann components. Tested by vertical loading, the experimental frame with 5 mm standard pins was 1.9 times as stiff as the PT frame, and with the 6 mm experimental pins it was 2.4 times as stiff as the PT frame. Clinical trials are needed to determine efficacy in vivo.

Assessment of fracture healing by spectral analysis

The 'in vivo' impulse response of long bones was investigated with the object of assessing the reliability of data taken under various conditions. The ultimate goal of the research is to develop a non-invasive method of monitoring the healing of long bones. A spectrum analyser was developed specifically for this investigation and is presented here.

Biomechanical evaluation of the Ender's pins, the Harris nail, and the dynamic hip screw for the unstable intertrochanteric fracture

While intramedullary fixation may have less operative morbidity than sliding plate systems, there also may be a loss of stability and strength of the fixation. In a biomechanical study with simulated unstable intertrochanteric fractures in cadaver femurs, multiple Ender's pins were 18% stronger than the single Harris nail. Compression hip screws were three times stronger than the Harris nail and two and one-half times stronger than Ender's pins. The compression hip screw was five times more rigid than either condylocephalic system.

Internal fixation in lumbosacral spine fusion. A biomechanical and clinical study

While the posterolateral technique is the accepted fusion method for chronic mechanical back pain, the results are variable and the indications are narrow. In an attempt to resolve this problem the role of internal fixation has been explored. Relative stiffness and strength under flexion loading of four lumbosacral fixation systems--(1) translaminar facet joint screws, (2) Luque rectangular box, (3) Luque fixation to the pelvis via the Galveston technique, and (4) two-part pelvic spinal rod system--were evaluated and compared to the normal spine with and without posterior ligaments. The stiffness of the normal intact spine was found to be nonlinear: the bending moment is a function of the square of the flexion rotation. Internal fixation resulted in a twofold increase in stiffness. Facet screws were 20% stiffer and the pelvic-spinal system 2.3 times stiffer (p = 0.001) than the Luque systems but all had similar strength. A retrospective study of 135 consecutive posterolateral lumbosacral spine fusions was conducted to determine what factors improved the fusion rate, clinical results, and time to fusion. Diagnosis and previous surgical treatment, discectomy or fusion, were of no significance. The radiographic and clinical results were highly correlated (p = 0.0001). Electrical stimulation failed to improve the results. Internal fixation with facet joint screws or rods to the pelvis was found to statistically decrease the pseudarthrosis rate and reduce the time required for spine fusion (p = 0.02). The surgical technique consists of translaminar facet screws and segmental fixation to the pelvis using a new implant system.

Long bone defects treated with demineralized bone

This study was undertaken to determine the potential of demineralized bone alloimplant (DBA) for healing long bone defects. We removed 25 mm of bone from the junction of the proximal and middle thirds of both ulnas in seven adult male mongrel dogs. On one side of each animal the devascularized bone was replaced as a cortical autograft (CA) and on the other side, the defect was filled with DBA. Because of implant error, there were only five CAs to evaluate, of which two had achieved clinical union. Of the seven DBAs only one achieved union. The bone in and around the defect was quantified on each specimen roentgenogram and was compared to the size of the original defect. The CA defects were filled 139% +/- 11% with bone that was partly new and partly remnants of the replaced autograft. The demineralized alloimplant defects were filled 143% +/- 45% with bone which, of course, was all newly formed. The difference between the two groups was not significant. We concluded that the DBA was an excellent osteogenic stimulant, but that it did not prevent nonunion in this model.

The effect of internal fixation without arthrodesis on human facet joint cartilage

Internal fixation of the spine combined with limited or no fusion has been advocated in the treatment of thoracolumbar fractures, spondylolisthesis, and severe juvenile spinal deformities. Internal fixation without arthrodesis of canine facet joints has been shown to result in the irreversible gross and histologic findings typical of osteoarthritis. Surgery was performed in eight patients for the treatment of thoracolumbar fractures. In each patient, Harrington distraction instrumentation was placed across at least two vertebral segments above and below the fused area. Instrumentation was removed six to 26 months following the initial surgery. A unilateral partial facetectomy was performed at the facet joint above the lower Harrington hook. Gross examination of the facet joints revealed areas of fibrillation, fissures, and thinning of the normal cartilaginous surface characteristic of osteoarthritis. Histologic examination revealed consistent areas of erosion of the vascular tidemark, osteophyte formation, subchondral remodeling, fibrillation, and loss of the normal cartilage cellularity. These findings were consistent with the histologic appearance of osteoarthritis. Internal fixation of the spine without arthrodesis is not an innocuous procedure and may be a predisposing factor in the development of symptomatic spinal arthritis.

A study of external skeletal fixation systems for unstable pelvic fractures

This study was undertaken to determine the feasibility of constructing an anterior pelvic external fixator capable of resisting displacement of vertical shear fractures. Newly designed tapered thread pins for cancellous bone had better bone pin fixation and their greater 6-mm diameter provided more than twice the stiffness of Hoffmann 4-mm pins when tested in clusters. Using these pins and a more rigid anterior frame as one model, various pelvic fixators were tested to determine their resistance to vertical shear forces. These tests determined that this new fixator was 16 times stiffer than a Bonnel single anterior frame and five times stiffer than a double anterior frame (both constructed of Hoffmann components). Extrapolation from the data shows that 13 mm of posterior fracture displacement would occur with loads of one half body weight using the new fixator. Additionally it was noted that Hoffmann frames constructed with two 5-mm pins performed as well as those using three 4-mm pins.

Surgical management of thoracolumbar spinal injuries. General principles and controversial considerations

Based on a review of the literature and experience with over 100 surgically treated thoracolumbar spinal injuries, the following information summarizes present knowledge of the subject. Reduction and internal fixation of the injured spine allows early mobilization of all patients, regardless of neurologic deficit, while protecting the neurologic structures from further injury and enhancing their recovery. The ability of the posterior ligamentous complex and the anterior bony column to withstand physiologic loads must be assessed by the history, physical examination, and radiography; then the injured structures should be protected from load or their function replaced by an appropriate surgical implant. Maximum neurologic recovery can be expected with prompt and complete decompression by reduction of the deformity, restoration of the spinal canal, and rigid internal fixation. The internal fixation system selected must provide compression for posterior injuries and distraction for anterior injuries, resist bending in combined injuries, and always restore normal spine shape. The rod-long, fuse-short technique provides the advantages of a more accurate reduction and a more secure fixation, and the minimum length of the fused region results in a more normal spine. The advantages of prompt and rigid but temporary internal fixation justify the risks both short- and long-term.

A locking hook spinal rod system for stabilization of fracture-dislocations and correction of deformities of the dorsolumbar spine. A biomechanic evaluation

Existing internal fixation systems for the injured or deformed spine present problems with overdistraction and control of the contoured rod necessary for transverse forces. A locking hook spinal rod avoids these problems by using a locking cover to secure the lamina in the hook and meshing radial grooves to lock the contoured rod to both the upper and lower hooks in 6 degrees intervals of rotation. The 7-mm stainless-steel rod is 50% stronger than the 1/4-in Harrington rod and also avoids the weakening effect of the notches. Cadaver spine testing gives nearly a threefold increase in failure strength (125 +/- 17 Nm versus 44.1 +/- 2.1).

Prophylaxis and management of hamstring muscle injuries in intercollegiate football players

Hamstring muscle strains were responsible for the loss of playing time of a significant number of football players at the University of Nebraska in the early 1970s. After the acquisition of a Cybex II isokinetic dynamometer, the number of injuries was noted to decrease. A retrospective study was performed over the period 1973 to 1982. Players in Group I, from 1973 to 1977, underwent a training program consisting of a supervised winter running program and self-designed year-long stretching, running, and weight lifting. Hamstring injuries were managed with rest, ice, and elevation initially and, by the third day, mild running was instituted. On the average, by the 14th day the athlete had demonstrated adequate speed and agility and was allowed to return to action. Group II consisted of players from the 1978 to 1982 period. These players received supervised winter running programs and staff-designed year-long stretching, running, and weight lifting programs. In addition, all athletes had baseline testing of hamstrings and quadriceps. Deficits were corrected to a desired ratio of 0.60. Injured players in Group II were treated with rest, ice, and elevation initially. High speed isokinetic workouts were begun on the third day with testing on the fifth day. They were allowed to begin jogging when the peak torque of hamstrings equaled 70% of baseline. Players returned to action when peak-torque reached a level of 95% of the baseline score or a hamstrings:quadriceps ratio of 0.55 or greater. Average time out of action was 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute bronchoconstriction induced by cotton dust: dose-related responses to endotoxin and other dust factors

Fifty-four healthy humans, selected for their acute airway responsiveness to cotton dust, had spirometric tests immediately before and after 6 hours of exposure to card-generated cotton dust from seven different cottons (of several grades and growing regions). During exposures, we measured airborne concentrations of viable fungi and bacteria (total and gram negative), vertically elutriated gravimetric dust, and vertically elutriated endotoxin. Correlation between each of these five exposure indices and exposure-related acute changes in forced expiratory volume in 1 s showed a statistically significant relationship between all of the indices except concentration of viable fungi. Of the other four indices, endotoxin was the most highly correlated (r = -0.94; p less than 0.00001), and gravimetric dust was the least correlated (r = -0.34; p less than 0.05). These findings suggest that gram-negative endotoxin may play a major role in the acute pulmonary response to inhaled cotton dust.

A comparison of grafting materials in experimental bone grafts

The abilities of seven different materials to stimulate healing of experimental defects in the ulna and scapula of the adolescent rabbit were compared. The results were evaluated radiographically and with vital fluorescent stain histology. By average radiographic score (ARS), defects implanted with autogenous iliac crest (ARS = 2.79) did significantly better (P<.01) than controls with nothing implanted (ARS = 2.00). Models implanted with hydroxyapatite (ARS = 1.75), collagen (ARS = 1.62), or frozen lyophilized cortical allograft (ARS = 2.21) were not significantly different (P>.05) from the control. Killing of graft cells with 5000 rads of cobalt-60 radiation did not significantly (P>.05) change the score for autogenous iliac crest (ARS = 2.56). The performance of demineralized allograft matrix (ARG = 2.84) was virtually the same as autogenous crest. Indexing terms: Demineralized bone, hydroxyapatite, alloimplant, osteogenesis.

Diagnosis of post-traumatic syringohydromyelia presenting as neuropathic joints. Report of two cases and review of the literature

Two paraplegic men with post-traumatic syringohydromyelia presented initially with neuropathic arthropathy of the elbow and shoulder, respectively. Both patients had sustained spinal trauma years earlier and had been lost to orthopedic and neurosurgical follow-up study. Characteristic history and physical findings were present in both patients. Conventional myelography failed to demonstrate the lesion in the first patient. The diagnosis in the second patient was confirmed by lumbar injection of low-dose metrizamide followed by immediate and delayed computerized axial tomography in the supine and lateral positions. Both patients were treated by surgical decompression and subarachnoid shunts with arrest of the neurologic deterioration. To the authors' knowledge, this is the first report of patients with post-traumatic syringohydromyelia presenting with neuropathic joints. The present case reports illustrate the need for long-term follow-up studies of patients with spine injury in specialty clinics. The use of computerized axial tomography and low-dose intrathecal metrizamide is advocated for diagnosing post-traumatic syringohydromyelia.

Complicated extremity fractures. The relation between external fixation and nonunion

In a series of 20 tibial fractures and ten radial fractures treated by external fixation, no association was found between the development of non-union and degree of soft tissue injury, delay in fixator application, or diaphyseal versus metaphyseal fracture site. Although the absence of fracture callus on roentgenograms of long bones immobilized by external skeletal fixation portends nonunion, no obvious cause-and-effect relation could be determined.

A locking hook-spinal rod: current status of development

A locking hook spinal rod previously demonstrated to be sufficiently stable and strong in cadaver experiments has been employed in 30 unstable thoraco-lumbar spinal injuries with results superior to Harrington instrumentation.

Reduction, stability, and strength provided by internal fixation systems for thoracolumbar spinal injuries

Anterior, posterior, and combined thoracolumbar spinal injuries were simulated in human cadaver specimens and then stressed in flexion, before and after stabilization, with Weiss Springs, Roy-Camille plates, vertebral body plates, and Harrington compression and distraction rods. The reduction, stability, and strength were determined for each implant-injury combination. For posterior ligamentous injuries, the Harrington compression system on the laminae gave reduction in extension, stability to that of the intact spine, and failure at 87.6 Nm bending load with 14.1 J energy absorption. For anterior vertebral body fracture, Harrington distraction rods from three vertebrae above to three below the injury gave a reduction in extension with stability similar to that of the intact spine. Failure occurred at 81.6 Nm load, one-third greater than with rods two levels above to two below, and 14.0 J energy absorption, twice that for the short rod. The more unstable combined anterior and posterior injury was satisfactorily reduced only by the long distraction system, which failed at 44.1 Nm load, twice that for the short rod, and 5.7 J energy absorption. By accurately determining what structures have been injured, and appropriate fixation device can be selected and the strength of the stabilized spine estimated. A thorough understanding of the biomechanics of the spine is essential for successful clinical utilization of these experimental data.