Increase of motion between lumbar vertebrae after excision of the capsule and cartilage of the facets. A cadaver study.

Seventeen fresh segments of cadaveric lumbar spines were tested in flexion, extension, and axial rotation. The resulting angular rotations were measured with the use of a goniometer and a three-dimensional system of video analysis. Measurements of flexibility were made, in order, in the intact spine; after decompression (bilateral total laminectomies, partial medial facetectomies, and foraminotomies); after excision of the capsule and cartilage of the facets; and after cancellous bone had been packed into the facet defects. Decompression resulted in a slight increase in the sagittal and axial ranges of motion. Subsequent excision of the capsule and cartilage of the facets, as in preparation for an arthrodesis of the facets, resulted in a significant increase in both the sagittal (5.7 +/- 2.9 degrees, mean and standard deviation) (p < 0.001) and the axial (1.4 +/- 0.9 degrees) (p < 0.01) ranges of motion compared with the motion in the intact specimen and with the motion in the specimen after only decompression had been done (p < 0.01 and p < 0.05, respectively). Packing of bone in the facets did not significantly reduce motion. It was calculated that the increase in the sagittal range of motion after excision of the capsule and cartilage of the facets would increase the tensile strain in a graft between the transverse processes of the fourth and fifth lumbar vertebrae (18 +/- 1 per cent tensile strain [mean and 95 per cent confidence interval] for the intact vertebrae and 25 +/- 1 per cent for the vertebrae in which the facets had been excised).

Extension-distraction fracture of the first lumbar vertebra.

STUDY DESIGN: This is a case report of an unusual fracture of the first lumbar vertebra in which the mechanism of injury appears to have been an extension-distraction force. The case report elucidates the patient's initial presentation at the time of injury, the treatment instituted, and follow-up revealing satisfactory healing of the fracture 18 months later. OBJECTIVES: The case is reported to illustrate an usual injury that had not been previously reported. SUMMARY OF BACKGROUND DATA: History, physical examination, and imaging studies from the time of injury, after initial treatment, and at final follow-up are presented. METHODS: A case report is presented in which a fall subjected a patient's stiff, osteopenic spine to an extension moment, resulting in tension failure of the bony elements of the anterior and middle columns. Plain radiographs, tomograms, and a magnetic resonance image detail the injury pattern; plain radiographs are presented as follow-up images. RESULTS: Nonoperative treatment in this case led to a satisfactory outcome at 18 months follow-up. CONCLUSION: An unusual extension-distraction fracture of the spine is presented, which, in this case, was satisfactorily treated nonoperatively.

Reconstruction after multilevel corpectomy in the cervical spine. A sagittal plane biomechanical study.

STUDY DESIGN: An in vitro biomechanical study of reconstruction techniques used after multilevel cervical corpectomy. OBJECTIVES: To determine the biomechanical behavior of the cervical spine after a multilevel corpectomy and reconstruction with a strut graft and supplementation of the graft with anterior and posterior plates. SUMMARY OF BACKGROUND DATA: Reconstruction of the spine after multilevel corpectomy represents a significant challenge, with nonunion or graft dislodgment being relatively common. Anterior and posterior plate fixation have increased the possibilities for supplemental stabilization. Although some clinical studies have been performed to examine multilevel corpectomies reconstructed with plates, biomechanical studies are few and are limited to single-segment models. METHODS: Flexibility testing was performed on 11 intact cervical spine preparations. Flexibility testing was also conducted on the spine preparations after reconstruction with a strut graft, after supplementation of the graft with an anterior plate, and after supplementation of the graft with lateral mass plates. Physiologic moments were applied dynamically, and the three-dimensional motion of the specimen was recorded with stereophoto-grammetry. Failure testing was performed on the plated specimens in compression. Load displacement curves and failure modes were analyzed. RESULTS: The range of motion after reconstruction compared with the control was decreased 24% after strut grafting, 43% after application of an anterior plate, and 62% after application of posterior plates. Similarly, flexibility coefficients showed that the posterior plate technique was the least flexible, followed by the anterior plate technique, with the graft alone being the most flexible reconstruction construct. Load to initial failure tended to be higher in posterior than in anterior plate specimens, and screw pullout was the predominant failure mode. CONCLUSIONS: The application of plates to the cervical spine as an adjunct to bone graft may improve the surgeon's ability to stabilize the spine after multilevel corpectomy. Understanding the biomechanics of these devices and the potential mode of failure is important in their use.

Axon regeneration after decompression of the conus medullaris.

STUDY DESIGN: The effect of acute spinal stenosis (simulating fracture) and decompression of stenosis on axon regeneration was evaluated in an animal model. OBJECTIVES: Clinical function and quantitative histomorphometry were used to gain insight into the clinicopathologic effects of acute spinal stenosis and decompression. SUMMARY OF BACKGROUND DATA: Decompression of extrinsic compression after thoracolumbar fractures has been suggested to maximize recovery of neurologic function. Clinical studies seem to support this, but the histologic results of decompression are poorly understood. METHODS: Experimental spinal stenosis was created in 5 female beagle dogs, followed by decompression in three of the beagles at 6 weeks. Clinical function and histologic appearance were analyzed using a monoclonal antibody to neurofilaments. RESULTS: Stenosis consistently produced significant neurologic deficit and axon degeneration within motor roots distal to the stenosis. Decompression resulted in improved neurologic function and a tendency for the axons to return to normal number and volume based on quantitative histomorphometry. CONCLUSION: This study provides an animal model and functional and histologic data that support the use of decompression of acute spinal stenosis of 50% or more canal compromise at the level of the conus medullaris and a neurologic deficit. This may be seen clinically in thoracolumbar fractures.

A kinematic study of the cervical spine before and after segmental arthrodesis.

STUDY DESIGN: The acute kinematic consequence of segmental arthrodesis in the cervical spine on the remaining open motion segments was studied in a cadaveric model. OBJECTIVES: To evaluate the distribution of motion across unfused cervical motion segments after a segmental arthrodesis. The applied load was determined as a function of arthrodesis length and level by using a fixed range of motion for the cervical spine (C2-T1). SUMMARY OF BACKGROUND DATA: An increased incidence of degenerative disease may exist at the levels immediately adjacent to a cervical arthrodesis as a result of alteration in biomechanical behavior at these levels. METHODS: One-, two-, and three-level fusions were simulated in multilevel ligamentous human cervical spines. Specimens were tested nondestructively through a 30 degrees range of sagittal plane rotation. Motion was recorded using three-dimensional stereophotogrammetry. Sagittal plane rotation of each motion segment in the fusion models was compared with the corresponding rotation in the unfused specimen. RESULTS: In the C2-C4 fusion, the increase in motion at C5-C6 was statistically less (P < 0.05) than the increase at C7-T1. In the C2-C5 fusion, the increase in motion at C5-C6 was statistically less (P < 0.05) than the increases at C6-C7 and C7-T1. For each of the five other fusion types tested, no statistical differences existed between the increases in sagittal rotation at any of the open motion segments. The bending moment necessary to produce 30 degrees of sagittal rotation increased nonlinearly as the number of motion segments fused increased. CONCLUSIONS: Under what was considered a realistic loading paradigm, sagittal plane rotation was not increased disproportionately at the motion segments immediately adjacent to a segmental arthrodesis in the cervical spine. The nonlinear rise in applied bending moment to achieve constant displacement was characteristic of the behavior of the ligaments and intervertebral discs throughout the spine as they underwent increasing deformation.

Cryotherapy-induced nerve injury.

Cryotherapy is a frequently used therapeutic modality in the treatment of athletic injuries. Peripheral nerve injury can result from the use of cryotherapy and cause temporary disability for the athlete. Six cases of peripheral nerve injury are reviewed. All cases resolved spontaneously. To avoid this complication, one should consider the location of major peripheral nerves, the thickness of the overlying subcutaneous fat, and the duration of tissue cooling.

Nerve injury in athletes caused by cryotherapy.

Cryotherapy is a therapeutic modality frequently used in the treatment of athletic injuries. In very rare circumstances, inappropriate use in some individuals can lead to nerve injury resulting in temporary or permanent disability of the athlete. Six cases of cold-induced peripheral nerve injury from 1988 to 1991 at the Sports Medicine Center at Duke University are reported. Although disability can be severe and can render an athlete unable to compete for several months, each of these cases resolved spontaneously. Whereas the application of this modality is typically quite safe and beneficial, clinicians must be aware of the location of major peripheral nerves, the thickness of the overlying subcutaneous fat, the method of application (with inherent or additional compression), the duration of tissue cooling, and the possible cryotherapy sensibility of some individuals.

Anterior stabilization of thoracolumbar burst fractures using the Kaneda device: a preliminary report.

Anterior decompression and fusion is a valuable technique in the treatment of thoracolumbar burst fractures. Anterior instrumentation has evolved to correct deformity and stabilize the spinal segments during decompression and bone grafting as a single-stage procedure. One anterior device developed by Kaneda has been used in our institution since 1989. This study is an initial review of our experience with this instrumentation. Anterior decompression and fusion augmented with the Kaneda device was performed in 20 patients with thoracolumbar burst fractures. Timing of surgery was early (< 15 days) in 13 patients, intermediate (16 to 120 days) in 2, and delayed (> 121 days) in 5. Sixteen patients were neurologically intact (Eismont grade D), 3 with distal weakness (Eismont grade B or C) and 1 with complete paraplegia (Eismont grade A). All patients with deficits recovered one Eismont grade after anterior decompression and fusion. Complications included pulmonary problems in 2 patients, a thoracic duct laceration requiring ligation, and a sympathectomy effect of the lower extremity. One patient had a pulmonary embolus and developed a hematoma at the graft harvest site while on anticoagulants with resultant meralgia paresthetica. There have been three screw failures and one definite pseudarthrosis. Anterior decompression and fusion supplemented by the Kaneda device was performed on 20 patients with thoracolumbar burst fractures. The average correction of kyphosis was approximately 50% acutely, with loss of approximately 50% of correction at follow up. In some patients, coronal plane deformity was created by the device. No effect on neurologic recovery could be shown with this small series. Perioperative complication rate was 30%, and 1 patient developed pseudarthrosis.

Oh, my aching back: evaluation and surgical treatment of lumbar spine disorders.

Low back pain is a common cause of disability and reason for seeking medical care. Surgery rates for low back pain are escalating, and the overall costs exceed $1 billion. Primary care physicians are increasingly responsible for the initial evaluations and management of these individuals. Recognition of surgical indications by these physicians will decrease costs by initiating management and will limit morbidity by expediting appropriate referrals. The important aspects of the evaluation of low back pain are reviewed in this article. Surgical indications in low back pain including infection, tumor, degenerative conditions, and nonacute traumatic sequelae are discussed.

Revision arthrodesis for tibiotalar pseudarthrosis with fibular onlay-inlay graft and internal screw fixation.

Pseudarthrosis after failed tibiotalar arthrodesis was successfully treated surgically in nine of 11 patients between 1980 and 1987. The indication for the initial attempted arthrodesis was traumatic arthrosis in seven patients, traumatic arthrosis with osteonecrosis of the talus in two patients, degenerative arthrosis in one patient with cavovarus foot (Charcot-Marie-Tooth), and myelodysplasia with progressive valgus deformity of the foot and ankle in one. The surgical technique planned for revision arthrodesis provided firm coaptation of tibia to talus with internal fixation that maintained the foot at right angles to the tibia with the forefoot in neutral position. Seven feet in 11 patients were treated using a transfibular approach that allowed excision of fibrous tissue and sclerotic bone, decortication of the media malleolus, fixation of the tibia to the talus with cancellous screws, and onlay/inlay fibular graft. Of the remaining four patients, one was treated with medial compression plate, a second was treated using an anteromedial cortical graft, a third was treated by a combination of sliding anteromedial corticocancellous graft and tibiotalar compression screw, and a fourth was treated with tibiotalar compression screw. Clinical and roentgenographic union occurred in nine of 11 patients. One patient developed a painless, fibrous union and one patient with persistent pseudarthrosis had myelodysplasia and severe valgus deformity and required amputation. Adequate exposure was possible through the transfibular approach to provide cancellous bone opposition, to excise the pseudarthrosis membrane and sclerotic bone, and to remove necrotic segments of the talus. In addition, supplemental bone graft, internal fixation, and postoperative cast immobilization were also helpful in obtaining union.

Cryopreserved anterior cruciate ligament allografts in a canine model.

This study was done to determine the clinical and biomechanical properties of cryopreserved anterior cruciate ligament allografts at 3, 6, 9, and 24 months after transplantation. A companion study of autografts was done to evaluate the effects of the surgical procedure and preservation on the tissue. The knee joints of 69 mongrel dogs (allograft n = 34, autograft n = 35) weighing 17 kg to 25 kg were grafted. Biomechanical results showed that maximum load was less in allografts than in autografts at each time interval. Deformation and slope were not significantly different between allograft and autograft. An apparent delay in revascularization and cellular repopulation was found in allografts compared with autografts, and collagen type I/type III ratios were similar in both grafts. DNA analysis indicated complete replacement of DNA in the graft by the host. Allografts provide adequate functional stability for daily activities in the canine model up to 2 years after transplantation. Biomechanical properties were relatively poor in allografts, which may lead to failure under more strenuous activity. The biologic similarity to autografts may indicate future remodeling potential.

Anterior decompression for late pain and paralysis after fractures of the thoracolumbar spine.

Anterior decompression of the thoracic and lumbar spine is indicated for patients with trauma, infection, or tumor that causes compression of the neural tissues, resulting in an incomplete neurologic deficit. The complication of chronic pain, with or without paralysis, that results from fractures with canal compromise has received little attention. This study involved 45 patients who had anterior decompression for chronic pain or paralysis at an average of 4.5 years after having thoracolumbar fractures. Pain was improved in 41 of 45 patients, with complete relief in 30 and partial relief in 11. In 25 patients with neurologic deficit, 21 noted improvement, 14 of which improved one or more grades of the Eismont classification. No patient had an increase in pain or loss of neurologic function. Complications were few. Anterior decompression of the thoracolumbar spine for chronic pain after thoracolumbar fractures is a safe and effective treatment for patients with this uncommon and difficult problem.

The relationship of the intrapelvic vasculature to the acetabulum. Implications in screw-fixation acetabular components.

The use of screw-fixation acetabular components in total hip arthroplasty could increase the incidence of vascular injury because of the increased use of drills and screws placed into the acetabulum in close proximity to major vessels. Analysis of two illustrative case studies, anatomic specimen cross sections, and computed tomographic scans demonstrate which vessels are at risk of injury should the inner cortex of the pelvis be penetrated. The iliac vessels are at risk of injury when penetration of the inner cortex of the pelvis occurs in the anterosuperior region of the acetabulum. The obturator vessels are at risk when penetration occurs in the anteroinferior quadrant of the acetabulum. The vessels can be within 0.5 cm of the inner cortex of the pelvis and tend to become closer with advancing age. Damage to the intrapelvic vessels may cause profound blood loss and hypotension when screw-fixation acetabular components are used. Rapid identification and immediate surgical repair of vessel lacerations are essential in the treatment of this complication.

Subgaleal hematoma in a child, without skull fracture.

The rare cases of subgaleal hematoma in childhood reported previously have all been related to head trauma. A case of apparently spontaneous subgaleal hematoma is reported which was associated with a qualitative platelet defect and not with trauma. Subgaleal hematoma must be differentiated from subgaleal infection and air from frontal sinusitis with bony erosion, and from an encephalocele or tumor erosion through the skull. Computed cranial tomography is useful in that differentiation. Most cases have been managed conservatively, but subgaleal tap may be indicated if there is severe headache or potential scalp necrosis.

Radiographic techniques for consistent visualization of total hip arthroplasties.

Using a chariot as a patient support system, it becomes possible to obtain consistent radiographic visualization of the hip. The chariot radiographs also allow for a more precise evaluation of the hip at follow-up visits. In most cases subsequent radiographs can be superimposed, differentiating between patient posture and biomechanical characteristics. The consistent patient positions and beam centering facilitate follow-up roentgenography with a higher degree of accuracy. True progression, particularly to a minor degree, can only be assessed with consistently reproducible positions for roentgenographic examinations. The chariot provides roentgenograms at a low cost and is a useful adjunct to diagnostic methods.

Effects of kyphosis and lordosis on the remaining lumbar vertebral levels within a thoracolumbar fusion: an experimental study of the multisegmental human spine.

This study was done to determine the motion of the whole lumbar spine after internal fixation and the effect of kyphosis and lordosis on the remaining vertebral levels. Baseline motion analysis of sagittal, frontal, and transverse planes was done to determine the intact range of motion. Three fusion configurations were tested: neutral position (0 degrees), 4.6 degrees +/- 2.0 kyphosis, and -6.2 degrees +/- 3.6 lordosis. The sagittal and frontal plane relative rotation of the instrumented segments (T12/L2) decreased an average of 74% and 60%, respectively, as compared with intact testing. Sagittal plane motion at the remaining segments increased for all fusion configurations when compared with intact motion and reached statistical significance at the L4/L5 level. No significant differences were found between fusion configurations (ie, fused neutral, kyphosis, and lordosis).