John S. Thalgott

Bone grafting alternatives in spinal surgery

BACKGROUND CONTEXT Bone grafting is used to augment bone healing and provide stability after spinal surgery. Autologous bone graft is limited in quantity and unfortunately associated with increased surgical time and donor-site morbidity. Alternatives to bone grafting in spinal surgery include the use of allografts, osteoinductive growth factors such as bone morphogenetic proteins and various synthetic osteoconductive carriers. PURPOSE Recent research has provided insight into methods that may modulate the bone healing process at the cellular level in addition to reversing the effects of symptomatic disc degeneration, which is a potentially disabling condition, managed frequently with various fusion procedures. With many adjuncts and alternatives available for use in spinal surgery, a concise review of the current bone grafting alternatives in spinal surgery is necessary. STUDY DESIGN/SETTING A systematic review of the contemporary English literature on bone grafting in spinal surgery, including abstract information presented at national meetings. METHODS Bone grafting alternatives were reviewed as to their efficacy in extending or replacing autologous bone graft sources in spinal applications. RESULTS Alternatives to autologous bone graft include allograft bone, demineralized bone matrix, recombinant growth factors and synthetic implants. Each of these alternatives could possibly be combined with autologous bone marrow or various growth factors. Although none of the presently available substitutes provides all three of the fundamental properties of autograft bone (osteogenicity, osteoconductivity and osteoinductivity), there are a number of situations in which they have proven clinically useful. CONCLUSIONS Alternatives to autogenous bone grafting find their greatest appeal when autograft bone is limited in supply or when acceptable rates of fusion may be achieved with these substitutes (or extenders) despite the absence of one or more of the properties of autologous bone graft. In these clinical situations, the morbidity of autograft harvest is reasonably avoided. Future research may discover that combinations of materials may cumulatively result in the expression of osteogenesis, osteoinductivity and osteoconductivity found in autogenous sources.

Stabilization of the lower thoracic and lumbar spine with the internal spinal skeletal fixation system. Indications, techniques, and first results of treatment.

Since 1984, 30 patients with burst fractures of the lower thoracic and lumbar spine were treated with AO internal spinal skeletal fixation system. All patients in this series had a minimum follow-up of 12 months. This new instrumentation is a posterior intrapedicular system developed by Dick in 1982. It allows stable fixation that is limited only to adjacent spinal segments. The internal fixator permits reduction in all three planes. Independently, it is possible to add distraction or compression to the involved segments. It also is able to reduce effectively the “middle column” which is thought to be accomplished by “ligamentotaxis.” In this series there were 16 neurologically intact patients and 14 with partial or complete neurologic injury. There were two minor instrumentation loosenings early in the series. Most patients in this series had a near-anatomic reduction of all three columns in the involved segment. It was also possible to re-establish the normal lordosis of the lumbar spine. The device provided sufficient rigid fixation for rapid postoperative mobilization in a light external orthosis.

Postoperative infections in spinal implants : classification and analysis : a multicenter study

A multicenter study was undertaken to analyze postoperative wound infections after posterior spinal instrumentation and fusion. The infection rate of these procedures has been documented in multiple reports. From these results, a classification scheme was developed that can guide therapy and determine the populations at risk. The patients were categorized according to two parameters, the first being the severity or type of infection, and the second being the host response or physiologic classification of the patient. This classification scheme is based on the clinical staging system for adult osteomyelitis developed by Cierny. The severity of infection is divided into three groups. Group 1 is a single-organism infection, either superficial or deep. Group 2 is a multiple-organism, deep infection. Group 3 is multiple organisms with myonecrosis. The host response, likewise, is divided into three classes. Class A is a host with normal systemic defenses, metabolic capabilities, and vascularity. Class B patients demonstrate local or multiple systemic diseases, including cigarette smoking. Class C requires an immunocompromised or severely malnourished host. Our data have demonstrated that single organisms, Group 1, generally can be dealt with by single irrigation and debridement, and closure over suction drainage tubes without the use of an inflow-irrigation system. The Group 2 patients, with multiple organisms and deep infection, required an average of three irrigation debridements. They have a higher percentage of successful closures with closed inflow-outflow suction irrigation systems when compared to simple suction drainage systems without constant inflow irrigation. Multiple- organism infections with myonecrosis, Group 3, are ex@ceedingly difficult to manage, and portend a poor outcome. Patients without normal host defenses, Classes B and C, are at high risk for developing postop@erative wound infection. Specifically, this study demon@strated that cigarette smoking may be a significant risk factor.

Anterior interbody fusion of the cervical spine with coralline hydroxyapatite

STUDY DESIGN A nonrandomized, retrospective human study of patients requiring anterior discectomy and reconstruction from C3 to T1. The pattern of incorporation, presence or absence of disc space collapse, maintenance of correction, and clinical outcomes were considered. OBJECTIVE To determine the efficacy of coralline hydroxyapatite as a bone replacement in anterior interbody fusions of the cervical spine used in conjunction with rigid plate fixation. SUMMARY OF THE BACKGROUND DATA Autograft is the gold standard for anterior interbody fusion of the cervical spine. Reported complication and morbidity rates with the use of autograft are as high as 21%. Using allograft instead of autograft presents numerous problems including lower rates of fusion. Other bone substitutes such as ceramics and polymethylmethacrylate are ineffective for fusion. METHODS Twenty-six skeletally mature patients underwent anterior decompression, stabilization, microdiscectomy, and reconstruction with Pro Osteon 200 (Interpore Cross International, Irvine, CA) coralline hydroxyapatite and AO anterior cervical locking plates. Iliac crest autograft, local bone, and allograft were not used. RESULTS The minimum follow-up period was 2 years (average, 30 months). There was no evidence of plate breakage, screw breakage, resorption of the implant, or pseudarthrosis. Two patterns of incorporation were identified. The implant incorporated totally in 100% of the disc spaces. Average hospital stay was 1.6 days. The average decrease in pain was 75.8%. There was no evidence of nonunion. CONCLUSIONS The use of Pro Osteon 200 with rigid anterior plating seems promising as a bone replacement in the cervical spine. The incorporation rate is exceedingly high, and the complication rate nonexistent.

Odontoid fractures treated by anterior odontoid screw fixation.

While odontoid fractures are common injuries, disagreement exists regarding treatment. Some authors claim a high rate of pseudoarthrosis and have therefore recommended early posterior fixation and fusion. This, however, results in decreased cervical rotation. Therefore, it has been recommended that a more direct approach to the fracture be taken. Results on anterior screw fixation in 14 patients are reported. The technique was found to be especially useful in multiple trauma patients, patients who refuse halo treatment, and in some nonunions.

Instrumented posterolateral lumbar fusion using coralline hydroxyapatite with or without demineralized bone matrix, as an adjunct to autologous bone.

BACKGROUND CONTEXT Autogenous posterolateral fusion with and without instrumentation has been reported with good results. However, difficult-to-fuse patients, such as smokers, elderly patients with poor bone quality and/or quantity, or patients with prior posterior surgeries, may have somewhat lower fusion rates. PURPOSE To determine the efficacy of coralline hydroxyapatite with or without demineralized bone matrix as a bone graft extender in a human clinical model with long-term follow-up. STUDY DESIGN/SETTING A retrospective series of 40 patients undergoing instrumented autogenous posterolateral lumbar fusion augmented with coralline hydroxyapatite with or without demineralized bone matrix. PATIENT SAMPLE Long-term clinical and radiographic follow-up were examined for 40 patients who underwent an instrumented posterolateral fusion only. Patients undergoing anterior lumbar interbody fusion (ALIF) procedures were not considered part of the sample. METHODS All patients underwent successful transpedicular fixation with autogenous posterolateral lumbar fusion. Fifteen cc of Pro Osteon 500 coralline hydroxyapatite (Interpore Cross International, Irvine, CA) was used at each level. An additional 10 cc of Grafton demineralized bone matrix gel (Osteotech, Eatontown, NJ) was used in 70% of these patients. RESULTS An overall fusion rate of 92.5% was achieved. Pain and function improvement were good but somewhat age dependent and correlated with the number of comorbidities. Patients with Grafton DBM gel had a lower fusion rate of 89.3%. CONCLUSIONS Based on this small retrospective review, coralline hydroxyapatite is an effective bone graft extender in difficult-to-fuse patients as an adjunct to autologous bone for posterolateral fusion of the lumbar spine when combined with rigid instrumentation.

Anterior lumbar interbody fusion with titanium mesh cages, coralline hydroxyapatite, and demineralized bone matrix as part of a circumferential fusion

BACKGROUND CONTEXT Anterior lumbar interbody fusion (ALIF) has become one of the primary choices for eliminating motion between vertebral segments in patients with severe discogenic pain and other lumbar pathologies. Autograft is the gold standard for spinal fusion. However, multiple authors have reported complication and morbidity rates associated with iliac crest harvesting to be as high as 25%. Drawbacks to the use of allograft in the anterior column include slower incorporation rates, the possibility for disease transmission, increasing cost resulting from stringent processing and unavailability on a worldwide basis resulting from religious and economic concerns. PURPOSE To determine the clinical and arthrodesis efficacy of coralline hydroxyapatite as an osteoconductive bone graft substitute in the anterior lumbar spine using a titanium mesh cage. STUDY DESIGN A series of 50 patients returning for long-term prospective follow-up, implanted with titanium mesh cages filled with coralline hydroxyapatite and demineralized bone matrix for ALIF as part of a circumferential fusion. PATIENT SAMPLE Long-term clinical and radiographic follow-up were examined for the first 50 patients undergoing this technique by one surgeon. OUTCOME MEASURES Pain was measured with a visual analog scale and function was measured with the Oswestry Disability Index. METHODS All 50 patients underwent successful ALIF with titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix, as well as an autologous posterolateral fusion with rigid posterior instrumentation. Patients filled out follow-up questionnaires and appropriate radiographs were taken. RESULTS A solid fusion rate of 96% was achieved. Mean pain decrease was 60% overall. A total of 70% of all patients either returned to work or to full home activities at a mean of 8 months after surgery. Ninety percent felt the surgery was successful. CONCLUSIONS The combination of titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix is effective for anterior interbody fusion of the lumbar spine when used as part of a rigidly instrumented circumferential fusion.

Single stage anterior cervical reconstruction with titanium mesh cages, local bone graft, and anterior plating

BACKGROUND CONTEXT After cervical corpectomy, the use of tricortical autologous bone to fill the large defect is biomechanically and structurally inadequate and may lead to excessive donor site pain and morbidity. The major alternative, fibular strut allograft, has inherent problems that lead to lower rates of solid arthrodesis and graft migration. Majd et al. reported on 34 cases with a 97% solid fusion rate using titanium mesh cages and local bone graft to fill the cervical corpectomy defect. PURPOSE With long-term results, to confirm the results previously reported by Majd et al. STUDY DESIGN/SETTING Retrospective chart and radiological review. PATIENT SAMPLE The first 26 patients in the senior authors practice eligible for a minimum 2-year follow-up, having had cervical corpectomy reconstructed with titanium mesh cages, local bone graft and anterior plating. OUTCOME MEASURES Odoms criteria were used to assess clinical outcome. Anteroposterior, lateral and lateral flexion and extension radiographs were used to assess fusion. METHODS Twenty-six patients with multilevel cervical pathology underwent successful corpectomy, decompression and fusion with titanium mesh cages filled with local bone graft. Rigid anterior plating was applied across the corpectomy defect. Preoperative, operative and postoperative chart data were collected retrospectively. Radiographic assessment included a minimum 2-year follow-up. RESULTS Follow-up ranged from 24 to 64 months. Clinically, 21 of 26 (80.7%) had an excellent or good clinical outcome. No radiolucencies or motion were detected on radiographic analysis, yielding a fusion rate of 100% (26 of 26). Broken or pulled out screws were identified in two patients, one of whom had plate revision. All cages remained intact with no evidence of cage settling or collapse. CONCLUSIONS The use of titanium mesh cages in conjunction with local bone graft, and rigid anterior plating is effective for cervical reconstruction after corpectomy and a viable alternative to the use of fibular strut allograft. These results confirm those previously reported by Majd et al.

A Prospective, Randomized, Blinded, Single-Site Study to Evaluate the Clinical and Radiographic Differences Between Frozen and Freeze-Dried Allograft When Used as Part of a Circumferential Anterior Lumbar Interbody Fusion Procedure

Study Design. Prospective, randomized clinical trial from a single surgeon’s patient population. Objective. The purpose of this study is to compare the outcomes and fusion rates of an anterior lumbar interbody fusion (ALIF) procedure when 2 different preservation methods of the femoral ring allograft (FRA) are used. Summary of Background Data. FRA can be stored via freeze-drying (FD) or freezing (FZ). In a previous biomechanical PLIF model, FZ cancellous allograft failed at an average load 50% less than FD cancellous allograft. Despite this finding, there is no evidence to support which preservation method is more effective at achieving solid fusion in ALIF procedures. Methods. Fifty ALIF patients received either FZ or FD FRA. Patients were observed for a minimum of 24 months. Outcome measures included complications, fusion status, implant intactness, 1 to 10 pain scale scores, Oswestry Disability Index (ODI), and SF-36 scores. Results. Univariate comparisons for grafting material are as follows: Average ODI-FD: 46.05 ± 16.7, FZ: 39.24 ± 23.65, P = 0.296. Average Physical Component Summary from SF36-FD: 33.47 ± 10.12, FZ: 39.76 ± 11.50, P = 0.074. Average 1 to 10 back pain with medication-FD: 3.47 ± 2.59, FZ: 2.95 ± 2.48, P = 0.527. ODI scores improved more than 10 points in 62.5% of patients. SF-36 Physical Component Summary scores improved more than 10 points in 27.5% of patients. Back pain with medication scores improved 2 or more points in 60.5% of patients. Seven patients required revision for psuedarthrosis (FD: 6, FZ: 1, P = 0.026). Fusion was achieved in 40 levels (71.4%). The freeze-dried graft had a higher likelihood of pseudarthrosis (P = 0.026). Conclusion. When the results are considered in terms of clinical outcomes, the 2 methods of graft preservation perform with few statistically significant differences. Radiographic analysis showed that the freeze-dried graft had a higher likelihood of pseudarthrosis.

Application and results of the AO internal fixation system in nontraumatic indications

The AO internal skeletal fixation system (ISFS) permits posterior spine fixation to be restricted to the vertebrae immediately adjacent to the lesion and allows manipulation of each instrumented vertebra in three planes. In a prospective study to assess the value of this fixation for adult spinal disorders, 68 patients were reviewed. The device was used in spondylolisthesis, postlaminectomy instability, post-traumatic kyphosis, degenerative scoliosis, spinal stenosis, tumors, and infections. A total of 322 transpedicular screws have been inserted without neurologic complication. Satisfactory results were achieved in 88% of the patients, and only four pseudarthroses (6%) occurred. The ISFS provides rigid stabilization to enhance bone graft consolidation and to allow rapid postoperative mobilization in a light external orthosis.