Biomimetic hydroxyapatite/collagen composite drives bone niche recapitulation in a rabbit orthotopic model.

Synthetic osteoinductive materials that mimic the human osteogenic niche have emerged as ideal candidates to address this area of unmet clinical need. In this study, we evaluated the osteoinductive potential in a rabbit orthotopic model of a magnesium-doped hydroxyapatite/type I collagen â€‹(MHA/Coll) composite. The composite was fabricated to exhibit a highly fibrous structure of carbonated MHA with 70% (±2.1) porosity and a Ca/P ratio of 1.5 (±0.03) as well as a diverse range of elasticity separated to two distinct stiffness peaks of low (2.35 â€‹± â€‹1.16 â€‹MPa) and higher (9.52 â€‹± â€‹2.10 â€‹MPa) Young's Modulus. Data suggested that these specific compositional and nanomechanical material properties induced the deposition of de novo mineral phase, while modulating the expression of early and late osteogenic marker genes, in a 3D in vitro model using human bone marrow-derived mesenchymal stem cells (hBM-MSCs). When tested in the rabbit orthotopic model, MHA/Col1 scaffold induction of new trabecular bone mass was observed by DynaCT scan, only 2 weeks after implantation. Bone histomorphometry at 6 weeks revealed a significant amount of de novo bone matrix formation. qPCR demonstrated MHA/Coll scaffold full cellularization in vivo and the expression of both osteogenesis-associated genes (Spp1, Sparc, Col1a1, Runx2, Dlx5) as well as hematopoietic (Vcam1, Cd38, Sele, Kdr) and bone marrow stromal cell marker genes (Vim, Itgb1, Alcam). Altogether, these data provide â€‹evidence of the solid osteoinductive potential of MHA/Coll and its suitability for multiple approaches of bone regeneration.

Microdecompression without fusion for radiculopathy associated with lytic spondylolisthesis.

Patients with symptomatic L-5 nerve root compression and associated lytic spondylolisthesis are commonly treated by bilateral wide posterior decompression and concomitant fusion, often accompanied by transpedicular instrumentation. More limited surgery aimed solely at the relief of nerve root compression offers the potential for significant relief of radicular pain while avoiding iatrogenic instability, thereby alleviating the need for arthrodesis with its increased surgical morbidity. Nine patients with unilateral radicular symptoms referable to the L-5 nerve root, minimal back pain, and a lytic pars lesion with mild spondylolisthesis underwent unilateral microdecompression on their symptomatic side without associated fusion. All patients obtained relief of radicular pain at both short- and long-term follow-up examination. One patient demonstrated increased back pain and, accordingly, the procedure is now recommended only for patients with no greater than a 25% spondylolisthesis. Unilateral microdecompression without stabilization is an effective and safe method for relieving radicular pain in patients with a lytic pars defect, a mild spondylolisthesis, and minimal back pain. This therapeutic option should be considered in select cases as an alternative to bilateral wide decompression with fusion and instrumentation.

Spine update lumbar interbody cages.

Interbody cage devices, used to assist interbody fusion, are rapidly gaining popularity in the surgical management of chronic low back pain. This update provides a structural classification of commonly used devices and assesses them against a set of clearly defined surgical goals, including ability to correct the existing mechanical deformation, ability to provide mechanical stability, ability to provide a suitable environment for arthrodesis, and ability to limit "built-in" morbidity. In addition, the materials used in the devices are examined regarding their biomechanical, biologic, and radiographic characteristics.

Traumatic vertical atlantoaxial instability in a case of atlanto-occipital coalition.

STUDY DESIGN: This is a report of a woman with an atlanto-occipital coalition who experienced a traumatic vertical atlantoaxial facet dislocation and severe associated neurologic injury. OBJECTIVE: To describe the radiographic and pathoanatomic characteristics of the injury process. SUMMARY OF BACKGROUND DATA: Severe injuries of the occipito-atlantoaxial complex are uncommon and only rarely are associated with patient survival. This is the first report of this particular injury. METHODS: Plain radiography and tomography demonstrated the facet dislocation and instability of the injury. Surgical exploration for repair of the torn dura mater and bony arthrodesis demonstrated the gross pathoanatomy. RESULTS: The patient's vertical atlantoaxial instability was stabilized, her dura mater reconstructed, and her necrologic status has improved to allow mobilization with a cane. CONCLUSION: Vertical atlantoaxial instability has not been described previously. From the somewhat subtle radiographic findings, one might underestimate the severity of the neurologic damage. Aggressive work-up and management of this injury is suggested to avoid potential further necrologic sequelae.

Spinous process osteotomies to facilitate lumbar decompressive surgery.

STUDY DESIGN: A technique for lumbar decompression using spinous process osteotomies is described, and the outcomes are studied prospectively. OBJECTIVE: To describe a technique that affords a wide exposure for decompression while minimizing damage to surrounding tissues, and to analyze the outcomes formally using the technique. SUMMARY OF BACKGROUND DATA: Commonly used techniques of lumbar decompression, which include bilateral takedown of paraspinal musculature and aggressive bony resection, can result in significant iatrogenic sequelae, whereas minimally invasive techniques often provide inadequate visualization and/or decompression. METHOD: Unilateral limited takedown of the multifidus is undertaken, followed by spinous process osteotomies at the involved levels. The spinous processes with the attached interspinous/supraspinous ligaments are then retracted. A complete "trumpeted" decompression is then undertaken. Fifty consecutive patients undergoing the procedure were analyzed prospectively and at follow-up by an independent observer using a validated functional outcome measure, a visual analog pain scale, and a patient satisfaction score. RESULTS: Functional outcome scores improved on average by 47%, pain levels were reduced by 66%, and high satisfaction rates were reported by 83% of patients. CONCLUSIONS: The technique affords excellent visualization and a wide area available for Kerrison use and angulation while minimizing destruction to tissues not directly involved in the pathologic process, including the paraspinal musculature as well as the interspinous/supraspinous ligament complex and facets. Additionally, it minimizes dead space and improves the cosmetic result.

Microdecompression for lumbar spinal canal stenosis.

STUDY DESIGN: A description of the technique for lumbar microdecompression and a prospective study of the outcomes. OBJECTIVE: To describe and analyze a technique that affords an excellent decompression while minimizing damage to surrounding tissues. SUMMARY OF BACKGROUND DATA: Commonly used techniques of lumbar decompression that include bilateral takedown of paraspinal musculature and aggressive bony resection can result in significant iatrogenic sequelae. A less destructive alternative is needed. METHODS: Unilateral limited takedown of multifidus was undertaken, and ipsilateral decompression performed. The contralateral side then was addressed under the midline structures with microscopic visualization--thereby preserving the supra-/interspinous ligament complex and the contralateral musculature. Thirty consecutive patients undergoing the procedure were analyzed prospectively and after a follow-up period by independent observers using a modified validated functional outcome score and patient satisfaction measures. RESULTS: The technique affords an excellent decompression while minimizing destruction to tissues not directly involved in the pathologic process. Functional outcome scores doubled, and 87% of patients reported high satisfaction rates. CONCLUSIONS: Lumbar microdecompression is a minimally invasive technique that appears to provide excellent functional outcomes.

Foraminal injection for lateral lumbar disc herniation.

Between 1986 and 1995, we treated with foraminal injection of local anaesthetic and steroids 30 patients with severe lumbar radiculopathy secondary to foraminal and extraforaminal disc herniation which had not resolved with rest and non-steroidal anti-inflammatory agents. They were assessed prospectively using standardised forms as well as the Low Back Outcome Score, and were reviewed at an average of 3.4 years (1 to 10) after injection by an independent observer (BKW). Relief of symptoms was obtained in 27 immediately after injection. Three subsequently relapsed, requiring operation, and two were lost to long-term follow-up. Thus 22 of the 28 patients available for long-term follow-up had considerable and sustained relief from their symptoms. Before the onset of symptoms 17 were in employment and, after injection, 13 resumed work, all but two in the same job. The average score before injection was 25 out of a possible 75 points. At follow-up, the overall average score was 54, and in those who had obtained relief of symptoms it had improved to a mean of 61. Based on these findings we recommend foraminal injection of local anaesthetic and steroids as the primary treatment for patients with severe radiculopathy secondary to foraminal or extraforaminal herniation of a lumbar disc.

Vascular anatomy anterior to lumbosacral transitional vertebrae and implications for anterior lumbar interbody fusion.

BACKGROUND CONTEXT: Anterior approaches to the lumbosacral spine afford the ideal window to the disc for interbody fusion. Vascular injuries represent the most feared complications of such approaches. Unfortunately, the combination of more procedures being performed, more surgeons at the beginning of the learning curve and less invasive techniques of approach combine to increase the risk of vascular injury in the face of altered vascular anatomy. PURPOSE: To assess cases in which vascular anatomy significantly altered the surgical approach to the lumbosacral junction. STUDY DESIGN/SETTING: Chart review of operative reports. PATIENT SAMPLE: All patients undergoing anterior lumbar interbody fusion between 1994 and 1997 at one large center. METHODS: We reviewed all cases of anterior lumbar interbody fusion performed between 1994 and 1997 to discover cases requiring significant alteration in approach because of vascular variation. RESULTS: One hundred seven consecutive cases were reviewed. Of these, 11 required significant alteration of the approach secondary to vascular variation. All 11 were in cases at the functional lumbosacral junction above a fixed transitional level. In only one case of transition was a usual approach able to be used. CONCLUSIONS: A consistent pattern of altered vascular anatomy anterior to the functional lumbosacral junction was found. This pattern is depicted and the surgical alterations required discussed. Such alteration in surgical approach was required in nearly all cases with transitional vertebrae and represented about 10% of cases overall. If anterior lumbar surgery is to be performed at the functional lumbosacral junction in the presence of transitional vertebrae, it is vital that close attention be paid to the vascular anatomy and more open techniques of approach should be considered.

Do facet joint capsular ligaments contain estrogen receptors? Application to pathogenesis of degenerative spondylolisthesis.

Studies showing that degenerative spondylolisthesis is 4 to 5 times more common in females than in males have suggested that hormonal influences account for this gender difference. Estrogen has been shown to play a role in other instabilities, such as those of the anterior cruciate ligament and the shoulder capsular ligaments, and estrogen receptors have been identified in these tissues. We wanted to assess facet joint capsular ligaments for the presence of such receptors. Accordingly, we collected facet joint capsular ligaments from 14 consecutive patients undergoing lumbar spinal fusion. Tissue sample analysis was performed by immunohistology using prediluted estrogen monoclonal antibody (Vantana) and automated immunostaining on a Vantana instrument. None of the specimens analyzed contained estrogen receptors. We conclude that, though degenerative spondylolisthesis may have hormonal influences, estrogen seems not to play a direct role in its development.

Mitchell osteotomy for adolescent hallux valgus.

Sixty-nine Mitchell osteotomies augmented with smooth-pin fixation and a trapezoidal step-off osteotomy to maintain ray length were performed on 46 adolescent patients with a painful hallux valgus deformity. Average follow-up time was 6 years. By using radiographic, clinical, and subjective patient data, we found an overall excellent or good result in 91% of cases. Nine feet were found to be cosmetically unsatisfactory, 11 required special shoewear, 10 had mild residual pain with high heels or strenuous running, and three had pain severe enough to restrict activities. Range of motion was normal in 56 feet, slightly decreased in 11 feet, and significantly reduced in two feet. We conclude that, given a success rate of 91%, this slightly modified Mitchell osteotomy is a satisfactory procedure for adolescent hallux valgus deformity with chronic bunion discomfort.

Mycobacterium avium intracellulare: vertebral osteomyelitis.

A case of vertebral osteomyelitis secondary to Mycobacterium avium intracellulare mimicking Pott's paraplegia is reviewed. To our knowledge, it represents the first published case in a patient without gross immunocompromise. The importance of early differentiation from tuberculous osteomyelitis is stressed as treatment regimens differ and outcomes may be affected.