The vascular anatomy anterior to the L5-S1 disk space.

STUDY DESIGN: Dissection of 37 human cadavers was performed to assess the variability in the vascular anatomy anterior to the L5-S1 disc space. OBJECTIVES: To determine the variability of the anterior vascular anatomy at the L5-S1 disc space, and to assess its reliability as an anatomic landmark for the placement of anterior interbody fusion devices. SUMMARY OF BACKGROUND DATA: Although multiple studies have defined both the lumbar spinal anatomy and the anatomy of the great vessels, the relation of the great vessels to the anterior L5-S1 disc space has not been quantified directly. METHODS: This study investigated 35 human cadavers (17 males and 18 females). The anterior L5-S1 disc space and great vessel bifurcation were exposed through a transabdominal approach. Two independent observers each obtained 10 measurements in each specimen. RESULTS: The middle sacral artery was present in 100% of the specimens, averaging 2.5 mm in width. Its location in relation to the midline was quite variable, with a range greater than 2 cm in both the top and bottom of the disc. The distance from the bifurcation to the top of the L5-S1 disc averaged 18 mm (range, 7-36 mm). The total width between the left common iliac vein and the right common iliac artery averaged 33.5 mm (range, 12-50 mm). CONCLUSIONS: The middle sacral artery, present in 100% of the specimens, is a poor anatomic landmark for locating the midline at L5-S1. Because the average space available between the left common iliac vein and the right common iliac artery is 33.5 mm, and because the left common iliac vein averages only 12 mm from midline, the surgeon must be prepared to mobilize the local vasculature in most cases to expose the L5-S1 disc space adequately.

Transient paraparesis: a complication of the surgical management of Scheuermann's kyphosis secondary to thoracic stenosis.

STUDY DESIGN: Transient paraparesis during the operative management of a 16-year-old patient with Scheuermann's kyphosis secondary to thoracic stenosis is reported. OBJECTIVE: To describe a treatable cause for paraparesis in a patient with Scheuermann's kyphosis undergoing surgical treatment. SUMMARY OF BACKGROUND DATA: Cord injury in the surgical treatment of Scheuermann's kyphosis is a rare event, yet it is felt to be more common in the surgical correction of kyphosis than in surgery for scoliosis. Suggested etiologies have included vascular insufficiency, hypotension, direct mechanical trauma, and neural element stretch. Concomitant thoracic spinal stenosis predisposing to neurologic injury during surgical manipulation has not been reported. METHODS: A 16-year-old boy with progressive Scheuermann's kyphosis measuring 80 degrees from T7 to T12 underwent an anteroposterior spinal fusion with somatosensory-evoked potential monitoring and wake-up tests. During the instrumentation posteriorly, somatosensory-evoked potential monitoring became markedly abnormal. This was followed by a wake-up test that demonstrated the patient's inability to move either of his lower extremities. All instrumentation was removed. The patient had recovered neurologic function by the time he reached the recovery room. A computed tomography myelogram was performed on the third postoperative day, which demonstrated severe thoracic stenosis from T8 to T10. The patient was returned to the operating room 1 week later to undergo a posterior laminectomy from T7 to T11 and instrumented fusion from T5 to L2. Somatosensory-evoked potential monitoring was stable throughout this procedure, and the wake-up test was normal. RESULTS: The patient's postoperative course and subsequent 2-year follow-up period were unremarkable. He progressed to clinical and radiographic union and maintained a normal lower extremity neurologic examination. CONCLUSIONS: A treatable cause for paraparesis secondary to the surgical treatment of Scheuermann's kyphosis is presented. The author currently obtains a thoracic magnetic resonance image (MRI) before the surgical correction of any patients with Scheuermann's kyphosis.

Thromboembolic complications after major thoracolumbar spine surgery.

STUDY DESIGN: Adult spinal surgery patients were studied prospectively to determine the incidence of subclinical deep venous thrombosis. An overlapping group of patients was reviewed retrospectively for symptomatic thromboembolism. OBJECTIVES: To determine the incidence of symptomatic and asymptomatic thromboembolism in spinal surgery patients. SUMMARY OF BACKGROUND DATA: Although thromboembolic complications are known to occur after spinal operations, there are limited published data on the incidence of pulmonary embolus or deep venous thrombosis after major spinal surgery. METHODS: One hundred sixteen adult spinal surgery patients were examined with duplex ultrasound to determine the incidence of deep venous thrombosis. Seventy-three of these patients also underwent lung perfusion scans to look for subclinical pulmonary embolism. A retrospective review was conducted of symptomatic thromboembolic complications occurring in a 2-year period at the authors' center. Three hundred and eighteen major spinal reconstructive procedures were performed during the period reviewed, which included the period of the prospective study and therefore the patients of the prospective group. Thigh-length compression stockings and pneumatic compression leggings were used for prophylaxis in all patients. RESULTS: One patient had an asymptomatic iliac vein thrombosis, and seven patients had symptomatic pulmonary embolism (2.2%). Six of the symptomatic pulmonary emboli occurred after combined anterior/posterior spinal fusions (6%), whereas only one occurred after posterior decompression and fusion (0.5%). CONCLUSIONS: Duplex ultrasound appeared insensitive for diagnosing clots before embolization in this patient group. Simple mechanical prophylaxis for thromboembolism, which may be adequate for patients undergoing posterior procedures, may not be as protective for patients undergoing combined anterior/posterior spine surgery.

The efficacy of anterior cervical plating in the management of symptomatic pseudoarthrosis of the cervical spine.

STUDY DESIGN: A retrospective review of 16 consecutive patients treated with anterior resection of the pseudoarthrosis, autogenous iliac crest bone grafting, and stabilization with an anterior cervical plate. OBJECTIVES: To determine the efficacy of anterior cervical plating used to manage symptomatic pseudoarthrosis of the cervical spine and obtain safe radiographic fusion and improved clinical results. SUMMARY OF BACKGROUND DATA: It is generally recognized that the clinical outcome of anterior cervical discectomy and fusion correlates with rates of fusion. There is debate in the literature as to how the patient with symptomatic cervical pseudoarthrosis should be addressed. Recent reports would support a posterior approach rather than a revision anterior approach. METHODS: Sixteen consecutive patients with symptomatic pseudoarthrosis of the cervical spine were treated with anterior resection of the pseudoarthrosis, autogenous iliac crest bone grafting, and stabilization with an anterior cervical plate. The average follow-up period was 51 months, and patients were assessed using physical examinations, questionnaires, and flexion-extension lateral radiographs. RESULTS: In all, 75% of the patients reported improvement of their symptoms, and 69% of patients returned to work. Fusions were graded I or II in 81% of the patients. No patient demonstrated radiographic instability, and none required revision surgery. Involvement with workers' compensation litigation negatively affected the clinical outcome. CONCLUSIONS: Patients in whom symptomatic cervical pseudoarthrosis develops after cervical anterior discectomy and fusion may be managed successfully with anterior resection of the pseudoarthrosis, autogenous bone grafting, and an anterior cervical plate. Successful clinical results regarding return to work status and general satisfaction with the surgical procedure depend not only on obtaining a successful radiographic fusion, but also on patient selection.

The effect of operative position and short-segment fusion on maintenance of sagittal alignment of the lumbar spine.

STUDY DESIGN: A retrospective radiographic assessment of the maintenance of sagittal alignment in patients undergoing short-segment instrumented fusions in a knee-chest position. OBJECTIVE: To determine whether the use of the knee-chest position adversely effects the maintenance of lumbar sagittal alignment in patients undergoing short-segment instrumented fusions of the lumbar spine. SUMMARY OF BACKGROUND DATA: Previous authors have demonstrated that lumbar lordosis is reduced in the knee-chest position, but it is unknown whether the kneeling position adversely affects the maintenance of lumbar lordosis in short-segment instrumented fusions during the follow-up period. METHODS: Twenty-eight patients (17 men and 11 women, 20-72 years of age) were reviewed retrospectively, having undergone short-segment fusions in the kneeling position. Seven patients underwent posterior spinal fusion from L4 to L5, 13 patients from L5 to S1, and 8 patients from L4 to S1. Transpedicular instrumentation and autogenous iliac crest bone grafting was used in all cases. Radiographs were assessed for sacral tilt, lumbar lordosis, and intervertebral angulation. Data were analyzed with repeated measures analysis of variance. RESULTS: The minimum follow-up period was 33 months. For all 28 patients, lumbar lordosis measured 51 degrees before surgery, 37 degrees during surgery (P = 0.0001), and 50 degrees after surgery (P = 0.6135). In patients undergoing L4-S1 posterior spinal fusion, sacral tilt measured 49 degrees before surgery and 45 degrees after surgery (P = 0.039). Although overall lumbar lordosis was maintained, lordosis was shifted proximally in the lumbar spine, increasing at L1-L4 from 19 degrees before surgery to 24 degrees after surgery, while decreasing at L4-S1 from 32 degrees before surgery to 26 degrees after surgery. CONCLUSION: Overall lumbar lordosis is well maintained in patients undergoing short-segment instrumented fusion in the kneeling position. With compensatory lordosis being shifted proximally and sacral tilt not returning to the preoperative status in L4 to S1 fusions, caution should be exercised in using the kneeling position for longer instrumented lumbar fusions.

Scheuermann's kyphosis in adolescents and adults: diagnosis and management.

Scheuermann's thoracic kyphosis is a structural deformity classically characterized by anterior wedging of 5 degrees or more of three adjacent thoracic vertebral bodies. Secondary radiographic findings of Schmorl's nodes, endplate narrowing, and irregular endplates confirm the diagnosis. The etiology remains unclear. Adolescents typically present to medical attention because of cosmetic deformity; adults more commonly present because of increased pain. The indications for treatment are similar to those for other spinal deformities, namely, progression of the deformity, pain, neurologic compromise, and cosmesis. The adolescent with pain associated with Scheuermann's kyphosis usually responds to physical therapy and a short course of anti-inflammatory medications. Bracing has been shown to be effective in controlling a progressive curve in the adolescent patient. For the adult who presents with pain, the early mainstays of treatment are physical therapy, anti-inflammatory medications, and behavioral modification. In patients, either adolescent or adult, with a progressive deformity, refractory pain, or neurologic deficit, surgical correction of the deformity may be indicated. Surgical correction should not exceed 50% of the initial deformity. Distally, instrumentation should be extended beyond the end vertebral body to the first lordotic disk to prevent the development of distal junctional kyphosis.

Vertebral column resection for the treatment of rigid coronal decompensation.

STUDY DESIGN: A retrospective study of patients with rigid coronal decompensation. OBJECTIVES: To determine if patients with rigid coronal decompensation can be safely and successfully treated by anterior-posterior vertebral column resection, spinal shortening, posterior instrumentation, and fusion to correct their deformities. SUMMARY OF BACKGROUND DATA: Previous investigators have described reconstructive techniques used to treat patients with sagittal and coronal spine deformities. These techniques include osteotomy and anterior or posterior fusion. Although a number of these studies consider the problems associated with failed back syndrome (flatback, coronal and axial imbalance, pseudarthrosis), they have not satisfactorily addressed the management of rigid coronal decompensation. The patient population of the current study, on average, presented with more severe, fixed deformities than those detailed in the literature, and required more extensive surgery than previously described. METHODS: Twenty-four patients (average age, 27 years) with rigid coronal decompensation underwent anterior-posterior vertebral column resection, spinal shortening, posterior instrumentation, and fusion. Degree of curvature was measured in the coronal and sagittal planes, and decompensation was assessed. Follow-up was from 2 to 10 years. RESULTS: Coronal and sagittal decompensation were corrected an average of 82% and 87%, respectively; T1 tilt and pelvic obliquity were improved by 65% and 53%, respectively; and scoliosis was improved by 52%. Complications occurred in 14 patients, but at follow-up all patients rated their results as either good or excellent. CONCLUSIONS: Patients with fixed, decompensated spinal deformity may be safely corrected by vertebrectomy, decancellation, spinal shortening, instrumentation, and fusion. Complications are transient, and the benefits in this select group of patients outweigh the risks.

Current concepts and management of patients with fixed decompensated spinal deformity.

The patient with a fixed decompensated spine deformity presents a difficult orthopaedic challenge. Consideration of the potential risks and benefits is critical with these patients before embarking on a significant surgical procedure. The deformity should be evaluated according to coronal, sagittal, and axial planes, with consideration given to where the major deformity exists. For deformities which exist in the sagittal plane only, a single stage posterior decancellation, known as the eggshell procedure, and posterior spinal fusion are preferred, rather than a 2 stage combined anterior and posterior approach. For deformities in the coronal plane, which are often associated with sagittal and axial malalignment, combined approaches are preferable for correcting imbalance. However, for severe, multiplane deformities where multiple osteotomies and recorrection are unlikely to safely produce balance, vertebral body resection with spinal shortening would be preferable. The authors' experience in treating fixed, decompensated spinal deformities is presented herein.

Bilateral pedicular stress fractures after successful posterior spinal fusion for adult idiopathic scoliosis.

A patient with adult idiopathic scoliosis who was successfully treated with posterior spinal fusion with segmental instrumentation from T3 to L4 is presented. One year after surgery fractures of both L4 pedicles developed, which were managed nonoperatively. Clinical union was achieved in 2 months and the patient was followed with serial computed tomographic scans to confirm union. A review of the current literature is also presented.

Treatment of scoliosis in the adult.

With the increasing awareness in both the medical community, as well as the general public of the progressive nature of adult scoliosis, more patients with this condition are coming to the attention of the spinal surgeon. With recent technical developments, the surgical armamentarium currently available has certainly improved, yet these patients remain a challenging population of patients. Infantile, juvenile, and adolescent idiopathic scoliosis are defined by their age of presentation. Similarly, adult scoliosis is defined as a presentation of scoliosis after skeletal maturity. Yet most studies in the literature define adult scoliosis arbitrarily as scoliosis existing in a patient age 18 or older. The majority of these patients, therefore, have curves which have persisted through adolescence into adult life with etiologies which mirror those of a younger patient population. Degenerative scoliosis related to osteoporosis and iatrogenic causes are additional etiologies of deformity which more typically present in adult patients. The indications for treatment in the adult patient are similar to those in the adolescent: progression of the deformity, pain, deterioration of pulmonary function, and perhaps cosmesis. The complications encountered during the surgical management of these patients is quite high (50-80%) when compared to their adolescent counterparts. Complications include pseudoarthrosis, loss of lumbar lordosis, thromboembolic disease, instrumentation failure, neurologic deficits, and wound infections. Therefore, even with the recent advances in surgical technique the decision of whether or not to operate on a given patient remains the single most critical decision.

The significance of calf thrombi after total knee arthroplasty.

We reviewed the records of 1257 patients having 1625 total knee arthroplasties; all had pre-operative and postoperative perfusion lung scans and postoperative venograms which were classified as showing no thrombi, calf thrombi or proximal thrombi. Patients with calf thrombi were found to have a significantly greater risk for both symptomatic and asymptomatic pulmonary embolism compared with patients with no venographic thrombi. There were positive lung scans in 6.9% of patients with calf thrombi compared with 2.0% of patients with negative venograms (p < 0.001). Symptomatic pulmonary embolism occurred in 1.6% of patients with calf thrombi compared with 0.2% of patients with negative venograms (p = 0.034). The risk of pulmonary embolism was not significantly different between patients with treated proximal thrombi, and those with calf thrombi. Patients who develop deep-vein thrombosis despite prophylaxis are at increased risk for pulmonary embolism; these patients should receive treatment, or undergo follow-up studies to detect proximal propagation.