Use of autologous growth factors in lumbar spinal fusion.

The results of spinal fusion, especially posteriorly above the lumbosacral junction, have been mixed. Autologous growth factor concentrate (AGF) prepared by ultraconcentration of platelets contains multiple growth factors having a chemotactic and mitogenic effect on mesenchymal stem cells and osteoblasts and may play a role in initiating bone healing. The purpose of this retrospective study is to review our results with AGF in lumbar spinal fusions. To date, AGF has been used in 39 patients having lumbar spinal fusion. The study group consisted of the first 19 consecutive cases to allow at least 6 months follow-up. The average follow-up was 13 months (range 6 to 18 months). Follow-up compliance was 91%. There were 7 men and 12 women. Average age was 52 years (range 30-72 years). Nine patients had prior back surgery. There were 8 smokers. AGF was used in posterior (n = 15) or anterior intradiscal (n = 4) fusions. AGF was used with autograft and coraline hydroxyapatite in all posterior fusions, and autograft, coral, and intradiscal spacer (carbon fiber spinal fusion cages or Synthes femoral ring) in intradiscal fusions. Posterior stabilization was used in all cases. Eight cases were single-level fusions, 6 were two-level, and 1 was a three-level fusion. Autologous iliac crest bone graft was taken in 14 cases and local autograft used in 5 cases. Posteriorly, a total of 23 levels were fused; of these, nine were at L5-S1, eight at L4-L5, five at L3-L4, and one at L2-L3. No impending pseudoarthroses were noted on plain radiographic examination at last follow-up visit. Solid fusion was confirmed in 3 patients having routine hardware removal, and in 2 patients who had surgery at an adjacent level. There was one posterior wound infection, which was managed without sequelae. When used as an adjunct to autograft, AGF offers theoretical advantages that need to be examined in controlled studies. Further study is necessary to determine whether coralline hydroxyapatite used as a bone graft extender in lumbar spinal fusion may help to obviate the need for secondary site graft harvesting.

Multiple drug metabolism: p-nitroanisole reversal of acetone enhanced aniline hydroxylation.

The unique effect of acetone on the p-hydroxylation of aniline was evaluated in microsomes prepared from control, phenobarbital- and 3-methylcholanthrene-pretreated animals. The existence of multiple forms of the hydroxylase was evaluated as an explanation of the acetone enhancement. Simultaneous metabolism of aniline in the presence of either p-nitroanisole (pNA) or ethylmorphine (EM) was evaluated to probe the participation of different mixed function oxidase systems. Aniline inhibited both N- and O-demethylation, while pNA and EM both inhibited p-hydroxylation of aniline. Acetone decreased the individual demethylation reactions, but enhanced aniline hydroxylation. In multiple drug reactions, acetone decreased N-demethylation and proportionately increased aniline p-hydroxylation. On the other hand, p-nitroanisole blocked the acetone enhancement of aniline metabolism. Kinetic evaluation of the acetone and p-nitroanisole effects on aniline metabolism indicated that each agent increased the apparent Km' by 4- to 5-fold for aniline in the hydroxylation reaction, but only acetone increased the Vmax'. From the Eadie-Scatchard analysis of the rates of aniline hydroxylation, acetone appeared to produce a biphasic increase in the hydroxylation above 0.75 mM aniline, even in the presence of pNA. Thus, multiple forms of the aniline p-hydroxylase are indicated by their altered activities in the presence of other drugs, and acetone seemed to specifically alter a species having a higher Km' for aniline.

Results of lumbar hemivertebral excision for congenital scoliosis.

The purposes of this study were to determine the long-term correction achieved by excision of lumbar hemivertebrae and the risk attendant. Seven patients had a follow-up of 41.14 months for lumbar hemivertebral excisions. Six had two-stage anterior vertebral body excision and, 7-8 days later, posterior lamina and pedicle excision with fusion. One patient had a single-stage correction. After surgery, the patients were in pantaloon casts or braces for a minimum of 6 months (supine, first 6-12 weeks). Hemivertebrae were at L2 (N = 1), L3 (N = 1), L4-L5 (N = 1), and L5-S1 (N = 4). Preoperative curves or hemivertebral angles averaged 36.6 degrees (range, 30-52 degrees). Average age was 7.5 years (range, 22 months to 12.5 years). Mean follow-up was 41.14 months. Surgical correction of the seven cases averaged 28.0 degrees. Two-stage procedures yielded 29.7 degrees correction with no complications; single-stage yielded 18 degrees correction, and the only complication was an L5 nerve root paresis.

The significance of hardware failure in anterior cervical plate fixation. Patients with 2- to 7-year follow-up.

STUDY DESIGN: In this retrospective study, the incidence of anterior cervical hardware failure was reviewed in 109 patients with degenerative disorders treated by one surgeon. OBJECTIVES: To evaluate the risk of injury caused by hardware failure in anterior cervical spine reconstruction. SUMMARY OF BACKGROUND DATA: Anterior plating is used for stabilization after cervical spine trauma and other conditions of instability. There has been a concern among surgeons about the risks involved when anterior cervical plating fails (fracturing or loosening of the construct). METHODS: The series included placement of 70 nonconstrained plates and 39 constrained plates. The average length of follow-up was 43 months. Hardware failure was defined as any broken or loosened screw or plate, regardless of clinical significance. RESULTS: There were 32 Orozco (Synthes, Inc., Paoli, PA) failures, 5 cervical spine locking plate failures, and 2 Orion (Sofamor Danek USA, Inc., Memphis, TN) failures. There were no injuries to tracheoesophageal or neurovascular structures as a result of hardware implantation or failure. CONCLUSIONS: The incidence of prominent hardware that endangers tracheoesophageal structures is minimal. In most cases, careful and long-term follow-up can ensure that failed hardware has not progressed and can confirm that late failure has not occurred. Hardware failure should increase the surgeon's suspicion of a nonunion, but immediate removal of the failed hardware is rarely necessary. If reoperation is necessary for nonunion repair, kyphosis correction, or other secondary procedures, the hardware can be removed at that time. Constrained systems (cervical spine locking plate, Orion) had significantly (P2 = 7.65, P < 0.01) fewer failures than the nonconstrained Orozco system.

Bone graft incorporation in radiographically successful human intervertebral body fusion cages.

STUDY DESIGN: Biopsies were obtained from within radiographically successful human intervertebral body fusion cages to document the histology of remodeling bone graft. OBJECTIVES: The purpose of this study is to describe the tissue within successful human interbody cages with special reference to the viability of bone and the presence or absence of debris particles. SUMMARY OF BACKGROUND DATA: The use of interbody fusion cages is gaining rapid acceptance, but there is little histologic documentation of the nature of tissue within successful human interbody fusion cages. METHODS: Needle biopsies were obtained of tissue within radiographically successful intervertebral body fusion cages at the time of pedicle screw removal for back pain or fusion of adjacent spinal level in nine spinal levels of eight patients. Preoperative diagnoses of these eight adult patients included disease conditions in the sagittal plane: spondylosis (5), degenerative disc disease (6), failed laminectomy and discectomy (2), radiculopathy (1), and spondylolisthesis (1). In all cases the cages had been packed with autograft (iliac crest 7, local 1) at the time of insertion. Cage implantation was performed with anterior (anterior lumbar interbody fusion 4, corpectomy and plate fixation 1), and posterior (posterior lumbar interbody fusion 4), segmental instrumentation (plate 1, or pedicle screws 8). All cases except one cervical case had posterolateral fusion or bilateral facet fusion. The cages were composed of carbon fiber-reinforced polymer (Brantigan cage; DePuy AcroMed, Raynham, MA, n = 5) or titanium mesh (Harms Cage; DePuy AcroMed, Raynham, MA, n = 4). Cages had been in situ from 8 to 72 months (mean 28 months). All nine biopsies from eight patients were obtained from within the center of the cages. Specimens were decalcified, routinely embedded in paraffin, stained with hematoxylin and eosin, and viewed qualitatively with transmitted and polarized light. RESULTS: All needle biopsies were obtained from within the center of the cages, and no patient developed spinal instability after the biopsy. All nine biopsies showed small fragments of necrotic bone associated with viable bone and restoration of hematopoietic bone marrow. Numerous cement lines demarcated the edges of previous cycles of remodeling. The ratio of necrotic to viable bone varied greatly among cases. Small particles of debris were associated with four of the five carbon-fiber cages and one of the four specimens from titanium cages, but there was no visible bone resorption or inflammation. CONCLUSIONS: Autogenous bone graft was incorporated in these radiographically successful human intervertebral body fusion cages. A few debris particles were observed, but there was no histologic evidence of particle-induced bone resorption or inflammation.

Surgical revision for failed anterior cervical fusions. Articular pillar plating or anterior revision?

STUDY DESIGN: This retrospective study reviewed one surgeon's experience in treating symptomatic anterior cervical pseudarthrosis by three methods: anterior revisions, posterior revisions, and circumferential procedures. OBJECTIVES: To determine whether anterior revision and plating achieves a higher probability of radiographic fusion and better clinical outcomes compared with posterior fusion and articular pillar plating. The role of circumferential procedures was evaluated. SUMMARY OF BACKGROUND DATA: Management of cervical pseudarthrosis by a repeat anterior procedure requires a difficult dissection in a previously operated area, resection of a nonunion site, and regrafting. Because the incidence of failure is reported to be high, posterior cervical fusion has been proposed as a treatment for anterior pseudarthrosis. METHODS: The second author has performed 44 surgical revisions for symptomatic anterior cervical pseudarthrosis. Before this surgical revision, all patients had pain and a radiographic nonunion that was confirmed during surgery. The average follow-up period after the secondary procedure was 28 months with a range of 12-60 months. All patients (100%) were available for follow-up evaluation. Twenty patients had anterior pseudarthrosis repair and anterior plating. Seventeen patients underwent posterior cervical fusion and articular pillar plating. Seven patients had a circumferential repair with anterior revision and posterior articular pillar plating. RESULTS: All seven patients (100%) who had circumferential procedures achieved a solid radiographic fusion. Clinically, five patients felt better than before surgery, and two patients felt the same. Sixteen of 17 patients (94%) with posterior repairs achieved a solid fusion. Fourteen patients felt better; two patients felt the same, and one patient with a nonunion felt worse than before surgery. A solid fusion was obtained in only 45% of the patients after anterior repair alone. CONCLUSIONS: Posterior cervical articular pillar plating and fusion result in a higher probability of fusion than repeat anterior procedures, even with the addition of anterior plate stabilization. Posterior fusion and articular pillar plating, whether alone or part of a circumferential procedure, provides the added fixation required to successfully repair failed anterior cervical fusions.

Anterior transpedicular fixation of the lower thoracic and lumbar spine. Experimental verification using a new direction finder.

Currently, no anterior spinal implant provides a strong bone-screw interface because of the cancellous characteristics of the vertebral body. A more secure anchorage could be obtained by anterior transpedicular screw fixation. Four hundred transpedicular screws located between T7 and L5 were placed using the newly developed direction finder. Measurements were obtained directly from radiographs of the cadaveric specimens. In 10 cases (2.5%), the screws crossed the medial pedicle border, but never by more than 1.4 mm. A lateral protrusion was noted in another 41 screws (10%), with no protrusion greater than 2.2 mm. Encroachments beyond the superior or inferior border were not observed. The mean angle of the screws at each level measured between 7 and 19 in the transverse plane and between 2 and 4.5 in the sagittal plane. This technique should be reserved for vertebrae without significant arthritic changes. The rare screw with minimal infraction through the medial or lateral pedicle wall should not cause any vascular or neural compromise. The anterior transpedicular screw technique appeared relatively safe (88%) and encouraged the development of the new plate system for anterior spinal stabilization.

Posterior cervical arthrodesis and stabilization with a lateral mass plate. Clinical and computed tomographic evaluation of lateral mass screw placement and associated complications.

STUDY DESIGN: A prospective study evaluating screw position and associated complications in 21 consecutive patients treated with a plate and screw fixation system applied to the lateral masses of the cervical spine. OBJECTIVES: To determine the clinical safety of lateral mass screws by determining their anatomic location and clinical complications in a consecutive patient series. SUMMARY OF BACKGROUND DATA: Lateral mass plating has been advocated for procedures in which wiring techniques cannot be used, especially in instances in which the posterior elements are deficient. METHODS: The first 21 consecutive patients who underwent posterior cervical arthrodesis and lateral mass plating with a single fixation system were reviewed prospectively. Computed tomography scans taken after surgery were reviewed independently by an orthopedic spinal surgeon and by a radiologist to evaluate screw tip position. Clinical and radiographic outcome was assessed at each visit after surgery. RESULTS: Ten of 164 (6.1%) lateral mass screws were malpositioned in six patients. Three symptomatic patients underwent four additional operative procedures to remove or replace the malpositioned screws. All patients had radiographic union, and no patient developed mechanical implant failure requiring removal of instrumentation. Radiographic evaluation noted that 17% of the screws were in the central axial zone of the lateral mass on computed tomography. CONCLUSIONS: Lateral mass plating was associated with no vertebral artery or spinal cord injury. There was a 1.8%-per-screw risk of radiculopathy, which corresponds with published cadaveric studies. Radicular symptoms improved with screw removal in each case. The advantages of segmental fixation achieved with lateral mass plates and screws must be weighed against the risk of radiculopathy.

The contoured anterior spinal plate system (CASP). Indications, techniques, and results.

The contoured anterior spinal plate (CASP) was developed for secure fixation of the anterior thoracolumbar spine. This is a report of 38 patients with various spinal pathologies treated with this system. The results were excellent regarding plate fixation and fusion. Comments on surgical technique and indications are provided.

The treatment of lumbar spinal pain syndromes diagnosed by discography. Lumbar arthrodesis.

STUDY DESIGN: This retrospective review of patients whose discogenic pain syndromes were treated by lumbar arthrodesis was designed to examine the clinical efficacy of this diagnostic modality and analyze possible confounding variables. OBJECTIVES: Clinical outcome was examined with respect to status of the arthrodesis, discographic diagnosis, and demographic variables. SUMMARY OF BACKGROUND DATA: Discography continues to be a controversial diagnostic technique for spinal pain syndromes. The morphologic information provided by discography is well known. However, disagreement exists concerning the clinical utility of the pain provoked by this modality. METHODS: Forty-eight patients were included in this study. In all patients, the chief complaint was low back pain. In all patients, the definitive diagnostic technique was lumbar discography followed by computerized tomographic scanning. All patients underwent lumbar arthrodesis. Data were collected in four categories: 1) demographic characteristics, 2) physical findings, 3) results of diagnostic studies, and 4) characteristics of surgical procedures. Data from these categories were studied with respect to clinical rating and status of the arthrodesis. RESULTS: Overall, 46% were judged to have a satisfactory clinical outcome at final follow-up. Forty-eight percent were judged to have a solid arthrodesis. CONCLUSIONS: Based on the results of this study, it appears that discogenic pain syndromes can be treated by arthrodesis.

Type II floating knee: ipsilateral femoral and tibial fractures with intraarticular extension into the knee joint.

Thirty-four patients with ipsilateral fractures of the femur and tibia with intraarticular extension into the knee of at least one fracture were reviewed at an average follow-up of 38 months. Joint involvement was present in 22 (65%) femoral fractures and 23 (68%) tibial fractures. In 11 (32%) patients, both fractures were intraarticular. In 71% of the patients, there were major associated injuries. Open fractures were common, occurring in 21 (62%) extremities. Associated vascular injuries were seen in seven (21%) cases. Ninety percent of the fractures were surgically stabilized. The average time to healing was 39 and 37.5 weeks for the femur and tibia, respectively. The average flexion of the knee was 96 degrees (5-140 degrees) with flexion contractures occurring in five (15%) knees. Results were graded according to criteria established by Karlström and Olerud. Only eight (24%) patients had good or excellent results. Complications were frequent, with deep infections occurring in 11 (32%) extremities, leading to above-knee amputations in three (9%) patients. This subgroup of floating knee injuries appears to be associated with a higher degree of systemic trauma, a higher percentage of open injuries, and a much graver prognosis.

Chylous injury following anterior spinal surgery: case reports.

Chylous leakage is an unusual complication following anterior spinal surgery. This leakage can occur as a result of traumatic injury to the thoracic duct, the cisterna chyli, or the retroperitoneal lymphatic vessels. The authors present case reports of three patients who underwent anterior spinal surgical procedures inadvertently complicated by an injury to the lymphatic system. All patients were managed nonoperatively with tube drainage and hyperalimentation and had uneventful recoveries.

Posterior percutaneous spine instrumentation.

Eighty consecutive cases of suprafascial pedicle screw stabilization were reviewed. Intraoperative fluoroscopy aided the percutaneous screw placement after structural anterior interbody graft(s) were placed. During routine outpatient hardware removal, all intradiscal fusions were stressed via the Shanz screws under fluoroscopy. Anterior reconstruction via a mini open approach coupled with this minimally invasive posterior approach led to a 96% successful fusion rate.

The use of titanium surgical mesh-bone graft composite in the anterior thoracic or lumbar spine after complete or partial corpectomy.

Various conditions such as fracture, dislocation, tumor, or infection adversely affect the vertebral body and lead to instability. Restoration of a stable anterior column is essential for normal spinal biomechanics. Various biological and mechanical spacers have been used to reconstruct the anterior column after corpectomy. In this retrospective review, the authors evaluated clinical charts and radiographs of 13 patients receiving titanium surgical mesh (TSM)-bone graft composite to reconstruct the anterior spinal column in the thoracic or lumbar region. The objective of this review was to evaluate the stability and efficacy of the TSM-bone graft composite in the anterior spine after a complete or partial corpectomy. Sixteen patients with involvement of the thoracic or lumbar vertebral column after trauma, tumor, or infection underwent partial or complete corpectomy. In all patients the anterior defect was reconstructed using a TSM-bone graft composite. Three patients died within 12 months postoperatively due to primary malignant process. Thirteen of 16 patient charts and radiographs were evaluated for anterior fusion status, settling of the TSM-bone graft composite, and hardware failure. No pseudoarthroses were noted. Evidence of solid anterior fusion was noted in all patients. The average settling of the TSM-bone graft construct was 3 mm. All patients presenting with only pain and no neurological symptoms (n = 9) experienced early pain relief. For patients presenting with neurological symptoms (n = 4), the recovery was complete in three and partial in one. No patient was made neurologically worse, and there were no vascular injuries intra- or postoperatively. The study suggests that TSM-bone graft composite offers excellent biomechanical stability in the immediate postoperative period, permitting progressive maturation of the fusion mass.

Anterior cervical allograft arthrodesis and instrumentation: multilevel interbody grafting or strut graft reconstruction.

This retrospective study evaluated a single surgeon's series of patients treated by multilevel cervical disc excision (two or three levels), allograft tricortical iliac crest arthrodesis, and anterior instrumentation. The objective of this retrospective study was to compare fusion success and clinical outcome between multilevel Smith-Robinson interbody grafting and tricortical iliac strut graft reconstruction, both supplemented with anterior instrumentation in the cervical spine. The incidence of nonunion for cervical discectomy and fusion varies widely depending on the number of disc levels involved, type of bone graft used, and whether the anterior grafting is supplemented with instrumentation. An alternative to multilevel interbody fusion is corpectomy and strut grafting, in which the incidence of nonunion has been reported to be 27% with autograft and 41% with allograft. Sixty-four consecutive patients who underwent allograft tricortical iliac crest reconstruction and anterior cervical plating were studied. The average follow-up was 39 months. There were 38 patients in the discectomy and interbody grafting group and 26 patients in the corpectomy and strut graft reconstruction group. Pseudoarthrosis occurred in 42% of the anterior cervical interbody fusion patients and 31% of the corpectomy patients. Nonunion in two-level interbody fusions occurred in 36% of the patients as compared to 10% for patients with one-level corpectomies; while 54% of patients with three-level interbody fusions and 44% of patients with two-level corpectomies were noted to have pseudoarthrosis. Higher percentages of nonunion were noted in multilevel interbody grafting than in corpectomy with strut grafting and when more vertebral levels were involved. These radiographic and clinical findings underscore the shortcomings of multilevel anterior cervical allograft reconstruction with plating. Corpectomy may be the preferred method when multiple disc levels are fused. In addition, anterior corpectomy affords decompression of significant osteophytes in a safer and quicker manner. In retrospective studies, there is a need for long-term follow-up before accurate statements can be made about the study population.