Transthoracic exposure for anterior spinal surgery.

The anterior approach to the vertebral column is used to treat fractures, spinal deformities, and destructive lesions secondary to tumor or infection. The thoracic surgeon, working with orthopedic surgeons and neurosurgeons, is uniquely qualified to provide surgical exposure expediently and assist in postoperative care. Forty-five patients with spinal deformities secondary to trauma (18 patients), congenital anomalies (16 patients), neoplastic disease (7 patients), and inflammation (4 patients) were treated by a transthoracic (37 patients) or thoracoabdominal (10 patients) anterior approach to the vertebral column. Two patients had subsequent operations. Free and vascularized rib grafts were used for stabilization and fusion with good results and few complications (8 patients). These results indicate that interspecialty cooperation results in expedient surgical exposure and good postoperative care.

Supracondylar fractures of the humerus: the role of dynamic factors in prevention of deformity.

In a retrospective survey of eighty-two children with supracondylar fractures of the humerus, forty were found to have sufficient clinical and roentgenographic data to classify the fractures as varus or valgus, and to determine the carrying angles at end result. The initial displacement (varus or valgus) of the distal fragment correlated with the final carrying angle, but the use of internal fixation, the adequacy of reduction achieved and the duration of traction or immobilization did not. The sixteen varus supracondylar fractures immobilized with the forearm in supination had a mean varus deformity of about 16 degrees, whereas the eight immobilized in pronation had a varus deformity of only 3 degrees. The findings in the few valgus fractures suggested that the valgus angulation was less at follow-up if they had been immobilized in supination. Dissection of eight cadaver limbs and electromyographic studies of one normal limb suggested that the position of the forearm affects the result by altering muscle tension.

Progression of congenital scoliosis due to hemivertebrae and hemivertebrae with bars.

From 315 cases of congenital scoliosis seen from 1925 to 1970, sixty cases of scoliosis or kyphoscoliosis due only to a hemivertebra, hemivertebrae, or a unilateral bar associated with the hemivertebrae were selected, classified into six types, and analyzed. Progression occurred in all but the balanced hemivertebrae group in two patients with cervical-high thoracic curves due to multiple hemivertebrae. Location of the hemivertebra or hemivertebrae and the presence of unilateral bars are the major determinants of deformity. The rate of progression of the scoliosis was variable, ranging from 1 to 33 degrees per year (average, 4 degrees per year).

Surgical management of lumbar spinal stenosis.

Eighty consecutive patients with lumbar spinal stenosis surgically treated during a 5-year period by the author were reviewed. Patients were placed in the following categories: lateral spinal stenosis (10), central-mixed stenosis (29), spinal stenosis after laminectomy and/or fusion (32), and spinal stenosis with degenerative scoliosis (9). Contrast-enhanced computed tomographic (CT) scans were helpful in determining the levels requiring decompression. However, in the multiply operated patient, contrast-enhanced CT scans were misleading in six patients. Patients with lateral spinal stenosis were treated with unilateral laminectomy and partial facetectomy. The 29 patients with central-mixed stenosis underwent decompressive laminectomy and bilateral facetectomies. Six fusions were done. In the nine patients with spinal stenosis and scoliosis, concaveside partial facetectomies and laminectomies were done as well as spinal fusions. The 32 patients with spinal stenosis after previous laminectomy and spinal fusions were the most difficult group to analyze, and their treatment was the least standardized. There were 19 good, eight fair, and five poor results in those who had undergone previous surgery. Fifty-seven of the 80 patients (71%) experienced a good result from their surgical treatment.

Rationale for spinal fusion in lumbar spinal stenosis.

In order to define the indications for spinal fusion in patients undergoing decompression for lumbar spinal stenosis, 114 patients surgically treated were reviewed. Follow-up was 24 to 108 months. Patients were grouped into four categories: 15 with lateral recess stenosis, 45 with central-mixed stenosis, 43 with stenosis following prior lumbar surgery(s), and 11 with scoliosis and spinal stenosis. Only two patients with lateral recess stenosis underwent fusion with fair results. Approximately one-third of those with central-mixed stenosis required a fusion. Results were good in 70%. In those with stenosis following prior lumbar surgeries, although not statistically significant, those who had concomitant decompression and arthrodesis had a better outcome than those in whom decompression only was done. Patients with scoliosis and stenosis had decompression for significant motor and reflex deficits and fusion over the length of their major curves. Patients having decompression for lumbar stenosis with degenerative spondylolisthesis, isolated disc resorption with degenerative facet joints, intervertebral disc disease with instability, and those with scoliosis with multidirectional instabilities benefit from concomitant spinal fusion.

Harrington-Bobechko instrumentation in the treatment of scoliosis: a preliminary report.

A dual hook system devised by Bobechko for use with Harrington and Moe distraction rods to eliminate postoperative orthotic support was employed in the surgical treatment of 57 patients with progressive scoliosis. Mean follow-up time was 33 months (range 15 to 56 months). Average correction was 51%, with an average loss of correction of 8 degrees. Five patients required reinstrumentation, two of whom had dislodgement of both upper hooks during the first postoperative week; the other three had rod breakage which occurred 3 to 20 months after surgery. The results indicate that the dual hook system provides greater security of fixation than a single hook construct, but has the disadvantage of bulkiness, making it prominent in thin patients. Postoperative protection with bracing for 6-9 months continues to be recommended to guard against instrument failure.

Use of cryopreserved bone in spinal surgery.

One hundred fifty-two consecutive spinal fusions were performed over a 4-year period in 143 patients. Autogenous bone was used in 62 patients and frozen cryopreserved bone in 90. A variety of anterior and posterior procedures with and without instrumentation were performed. The percentage of successful arthrodesis was 87 in those who received autogenous bone, and 86.6 in those who received allograft bone. Thirty-four spinal fusions were surgically explored. Histologic evaluation of the bone taken at the time of surgical exploration showed viable osteocytes laying down osteoid, woven and lamellar bone, and no inflammatory or foreign body reaction. The authors conclude that cryopreserved bone, harvested and processed as described, is advantageous, safe, and results in a rate of bone union comparable to that of autogenous bone.

Knodt rod distraction instrumentation in lumbosacral arthrodesis.

Review of 40 patients undergoing lumbosacral fusions over a 4-year period was done to determine the value, efficiency, and safety of Knodt rod distraction instrumentation. The age range was 30-80 years. Mean age was 51 years. Follow-up was 1-4 years. Twenty patients underwent decompression and fusion for spinal stenosis, nine underwent spinal arthrodesis for instability, six underwent the same for spondylolisthesis, and five underwent fusions for other diagnoses. A posterior midline approach was used. Laminal hook sites were prepared, and care was taken to prevent dural compression or tenting. Balanced distraction was done to restore soft tissue tension and stability. No attempt was made to reduce deformity. A posterior and lateral mass fusion augmented with allograft bone was performed on all but three patients, in whom autogenous bone was used. The majority of patients were placed in a custom-molded lumbosacral orthosis for 3-6 months after operation. There were no neurologic complications, dural tears, or pseudomeningoceles. The first sacral laminas were instrumented in 22 patients. Nine of the 40 patients underwent rod removal. Reasons for removal were pain due to loosening in five patients and failure of fusion in two. On rod removal in two patients, no abnormality was found. Insertion within the sacral laminas did not lead to neurologic complications. The major problem appeared to be loosening, which necessitated rod removal in 12% of the patients. Knodt rod distraction instrumentation is a safe and effective method of internal fixation for lumbosacral fusions.

Evaluation of cryopreserved bone and synthetic biomaterials in promoting spinal fusion.

The purpose of the study was to evaluate the use of cryopreserved allograft bone and tricalcium phosphate in promoting spinal fusion. Nine 20-30 lb swine underwent posterior spinal fusion at T5-T6, T13-T14, and L2-L3. Autogenous bone, cryopreserved allograft bone, or equal parts of allograft bone and tricalcium phosphate were added to the decorticated posterior elements. A total of 27 sites were prepared for fusion. The spines were retrieved at 6 months and evaluated for integrity and stability of the fusion sites by clinical examination, three-point bending tests, multiplanar radiographs, and undecalcified tetracycline-labeled and decalcified histologic sections. The nine sites that received autogenous bone were solidly fused. There were one clinical and two radiographic nonunions in the nine sites that received cryopreserved allograft bone. Sites that received a mixture of allograft bone and tricalcium phosphate demonstrated slight motion at two locations and radiographic evidence of fusion at all levels. The extent and degree of fusion was not site-specific. Three-point bending analysis did not demonstrate a significant trend as to site or materials specificity. No adverse histologic response was noted. Histologic sections and tetracycline labels confirmed abundant new bone formation at all sites at 6 months. Although autogenous bone remains the gold standard for use in spinal arthrodesis, this study demonstrates the value of cryopreserved allograft bone alone and in combination with tricalcium phosphate in promoting spinal fusion.

Surgical management of isthmic spondylolisthesis.

In order to determine the factors that produce a successful outcome in the surgical management of spondylolisthesis, 44 consecutive patients who underwent surgical treatment were reviewed. Preoperative evaluation was directed towards determining the presence or absence of nerve root compression. The patients without nerve root compression typically underwent fusion alone, while those with evidence of nerve root compression had decompression and fusion. After an average 36-month follow-up, results were good in 78%, fair in 18%, and poor in 4%. There were five complications, all of which were successfully managed. Two patients required reoperation for pseudoarthrosis. An eventual 100% fusion rate was achieved. Results in the patients with Grade III or Grade IV olisthesis were nearly equivalent to the less severe cases. Nine patients received allograft, with a fusion rate equal to the 32 receiving autogenous bone. This study suggests that in patients who have isthmic spondylolisthesis with mechanical lumbar symptoms only, or in patients with low-back pain with radicular extremity pain caused by nerve root irritation, fusion alone is indicated. In patients with documented radiculopathy resulting from nerve root compression, decompression in addition to fusion is indicated.

Multiaxis cyclic biomechanical testing of Harrington, Luque, and Drummond implants.

The performance characteristics of Harrington-Moe distraction rods, paired wired Luque rods and Drummond's system were evaluated and compared when subjected to nondestructive cyclic, multidirectional biomechanical testing. Twelve fresh, frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing machine. The instrumented spines were subjected to 207 kN/m2 compression and 49 N-m torsion. Each spine was cycled 28,000 times at 1 cycle per second. Linear and angular displacements were determined by digitizing photographs and video tapes made during testing. A computer program developed and refined for the project was used to complete the data analysis. Approximately 540 items of angular and linear displacement data were collected for each spine. Inspection of the spines after cyclic, multidirectional testing revealed no change in their osteoligamentous integrity compared with pre-testing. Pre- and post-testing radiographs showed no evidence of osseous failure, hook dislodgement or wire breakage. Erosion of laminal bone at the Harrington hook attachment sites was observed. Displacement of the Harrington hooks was seen during off-axis compression-torsion testing. Fretting and deposit of metal wear debris occurred between the sublaminal wires and "L" rods. There was no evidence of loosening of either the Drummond or Luque implants or fatigue failure of any component. Analysis of the linear and angular displacement data showed that the Luque and Drummond instrumented spines displaced less in axial compression, off-axis compression and off-axis compression-torsion than the single Harrington-Moe distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic axial loading of spinal implants.

The performance characteristics of Harrington distraction rods were evaluated and compared with paired wired L-rods when subjected to cyclic axial compression loading. Twelve fresh frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing device. Nine spines were displaced 2.54 cm over 10,000 cycles at a pressure of 10.3-13.8 kN/m2 (15-20 psi). Four spines were mounted in an Instron machine (Instron Engineering Corp., Canton, MA). Load displacement curves were determined for each spine without instrumentation, with Harrington distraction rod and with paired wired L-rods. Results of this cyclic axial compression testing showed that the Harrington distraction rod allowed 0.5 cm shortening in contrast to the L-rods that permitted 1.5 cm of axial displacement. Friction movement and metallic debris were noted between the sublaminal wires and the L-rods. The Luque Instrumented spine showed greater coronal plane displacement than the Harrington instrumented spines. Displacements in the sagittal plane were greater with the Harrington than Luque instrumented spines. Rotation changes in the sagittal plane were greater with the Harrington than Luque instrumented spines. Load displacement curves done on four spines indicated a wide range of applied load, 356 N (80 lbs) to 712 N (160 lbs) being necessary to displace the spines 2.54 cm. The clinician should be aware that the Luque system does not resist imposed axial compression loading in the axial and coronal planes as well as the Harrington distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomical observations on the acromioclavicular joint and supporting ligaments.

An anatomical study of the acromioclavicular (AC) joint and its supporting ligaments was performed using both macroscopic and microscopic methods. The project used 63 cadaver shoulders of unknown ages. Fifty-three joints were used for macroscopic and 10 for microscopic study. The data consisted of micrometer measurements of the dimensions of the extrinsic and intrinsic ligaments of the AC joint; measurement and description of the intraarticular meniscus and the superior and inferior capsular ligaments of the AC joint; and the anatomical course and relationship of the coracoacromial (CA) ligament to the supporting ligaments of the AC joint and a description of its insertion on the acromion process. The following observations were made: The coracoclavicular ligament, especially the trapezoid ligament, provides significant soft tissue restraints to upward displacement of the clavicle. A complete AC joint disc was found in only one, meniscoid discs in 25, remnants of discs in 16, and no discs in 11 of the 53 joints studied macroscopically. (No age correlation was made since the ages of the cadavers were unknown). The CA ligament interconnects with the inferior capsular ligament of the AC joint as well as with the coracoclavicular and coracohumeral ligaments. It also has a broad area of insertion on the inferior acromial surface. The CA ligament appears to function as a buffer between the acromion and the rotator cuff, and to provide support for the AC joint. Transection of the CA ligament may result in loss of this buffering function.

Synthetic biomaterials for spinal fusion.

Calcium hydroxylapatite (HAP), tricalcium phosphate (TCP), and Bioglass (BG) were implanted in the spines of dogs to determine their potential in augmenting and enhancing spinal fusion. HAP and TCP showed continuous bone to biomaterial interfaces of varying degrees. Trabecular bone surrounded and incorporated the particulate hydroxylapatite. Tricalcium phosphate ceramic showed little evidence of resorption. The glass particulate, BG, showed a thin, fibrous encapsulation with some adjacent bony trabeculae. Decortication and autogenous bone enhanced incorporation. This multivariant initial study showed that trends found for the biomaterials implanted independently were similar to those used in combination. No adverse tissue reactions were noted for the combination of materials.