Corpectomy followed by the placement of instrumentation with titanium cages and recombinant human bone morphogenetic protein–2 for vertebral osteomyelitis

Use of Recombinant Human Bone Morphogenetic Protein-2 After Anterior Cervical Corpectomy and Fusion for the Treatment of Vertebral Osteomyelitis

OBJECTIVE

To report the operative outcomes after treating vertebral osteomyelitis patients with an anterior cervical corpectomy and fusion procedure using recombinant human bone morphogenetic protein-2 (rhBMP-2) as graft material.

METHODS

A retrospective review of electronic medical records of 26 adult patients who underwent an anterior cervical corpectomy and fusion procedure for cervical osteomyelitis using rhBMP-2 at the University of Puerto Rico University District Hospital was performed. Indication, preoperative laboratory results, levels of corpectomy, preoperative American Spinal Injury Association Impairment Scale (ASIA) score, complications, fusion evaluation at 12 months, and ASIA score at 12 months were reviewed.

RESULTS

For the cohort of patients, mean age was 47 ± 13 years and 65% were male. Spinal instability was present in 54%. The levels of corpectomy were: 1 level in 2 cases, 2 levels in 15 cases, 3 levels in 8 cases, and 5 levels in 1 case. Four patients had complications and, of these, 2 experienced dysphagia. The fusion rate was 100% and no reoperations were performed. An improvement in ASIA score was seen for 54% patients at 12-month follow-up.

CONCLUSIONS

This study demonstrates a fusion rate of 100% with no reoperations reported. Recombinant human bone morphogenetic protein-2 could be considered and further researched as grafting material for anterior cervical corpectomy and fusion procedures in cervical osteomyelitis patients.

Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Delayed Esophageal Perforation Diagnosed 12 Years After Anterior Cervical Diskectomy and Fusion: A Case Report and Review of Current Literature

Esophageal perforation associated with anterior cervical diskectomy and fusion (ACDF) is a rare but serious complication. ACDF-related esophageal perforations can be acute or delayed. Delayed perforations more than 10 years after ACDF are exceedingly rare. Here, a delayed esophageal perforation discovered 12 years after a three-level ACDF is presented. This case highlights two main points. First, all diverticula after an ACDF warrant close clinical monitoring. Second, routine follow-up should be performed for patients with screw pullout to assist in early diagnosis of delayed esophageal perforation.

Technical nuances and approach-related morbidity of anterolateral and posterolateral lumbar corpectomy approaches-a systematic review of the literature

Purpose

Approaches for lumbar corpectomies can be roughly categorized into anterolateral (AL) and posterolateral (PL) approaches. It remains controversial to date whether one approach is superior to the other, and no comparative studies exist for the two approaches for lumbar corpectomies.

Methods

A systematic review of the literature was performed through a MEDLINE/PubMed search. Studies and case reports describing technique plus outcomes and possible complications were included. Thereafter, estimated blood loss (EBL), length of operation (LOO), utilized implants, neurological outcomes, complication rates, and reoperation rates were analyzed.

Results

A total of 64 articles reporting on 702 patients including 513 AL and 189 PL corpectomies were included in this paper. All patients in the PL group were instrumented via the same approach used for corpectomy, while in the AL group the majority (68.3%) of authors described the use of an additional approach for instrumentation. The EBL was higher in the AL group (1393 ± 1341 ml vs. 982 ± 567 ml). The LOO also was higher in the AL group (317 ± 178 min vs. 258 ± 93 min). The complication rate (20.5% vs. 29.1%, p = 0.048) and the revision rate (3.1% vs. 9.5%, p = 0.004) were higher in the PL group. Neurological improvement rates were 43.8% (AL) vs. 39.2% (PL), and deterioration was only noted in the AL group (6.0%), while 50.2% (AL) and 60.8% (PL) showed no change from initial presentation to the last follow-up.

Conclusion

While neurological outcomes of both approaches are comparable, the results of the present review demonstrated lower complication and revision rates in anterolateral corpectomies. Nevertheless, individual patient characteristics must be considered in decision-making.

Minimally invasive lateral retroperitoneal transpsoas approach for lumbar corpectomy and fusion with posterior instrumentation

In this video, the authors highlight the operative treatment of a 55-year-old man with chronic osteomyelitis discitis. The operation entailed a minimally invasive lateral retroperitoneal transpsoas approach for L3 and L4 corpectomies, L2–5 interbody fusion, and L2–5 minimally invasive posterior instrumentation. The operation proceeded in two stages, beginning in the lateral position with corpectomy of the L3 and L4 vertebral bodies and placement of a corpectomy cage. After closure of this access wound, the patient was turned to a prone position for the posterior element of the operation. Posterior instrumentation was placed with pedicle screws at L2 and L5.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2210

Vascularized Bone Flap Options for Complex Thoracic Spinal Reconstruction

BACKGROUND

Osseous reconstruction following total spondylectomy/vertebrectomy in the thoracic spine is indicated to restore spinal stability. To assist with bony reconstruction, vascularized bone flaps including free vascularized fibula flaps and pedicled rib flaps can be used. However, there are limited data comparing various techniques. The authors aimed to evaluate the outcomes of free vascularized fibula flaps and pedicled rib flaps used for thoracic spinal reconstruction.

METHODS

The authors reviewed 44 vascularized bone flaps [10 anterior pedicled rib flaps, 25 posterior pedicled rib flaps, and nine vascularized fibula flaps] for corpectomy defects spanning T1 to L1 between January of 1999 and June of 2018. Mean age and follow-up were 46 ±17 years and 74 ± 52 months, respectively.

RESULTS

The union rate was 93 percent, with a similar mean time to union among the three groups: free vascularized fibula flaps, 9 ± 4 months; anterior pedicled rib flaps, 9 ± 6 months; and posterior pedicled rib flaps, 9 ± 5 months (p = 0.95). Surgical-site complications were found in 27 vascularized bone flaps (61 percent), and reoperations and revisions were performed in 14 (32 percent) and 10 (23 percent) vascularized bone flaps, respectively. No differences were identified among anterior pedicled rib flaps, posterior pedicled rib flaps, and vascularized fibula flaps with regard to complication, reoperation, and revision rates.

CONCLUSIONS

Free vascularized fibula flaps and pedicled rib flaps provide durable reconstruction for thoracic spinal defects. Union, time to union, revision, and reoperation rates were similar among anterior and posterior pedicled rib flaps and vascularized fibula flaps. Given the variability in indication and defect types among the flap cohorts, the authors' results should be interpreted carefully as an insight into the outcomes of different vascularized bone flaps for the unique cases of thoracic spinal reconstruction rather than to compare the different flaps used.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

BMP use in the surgical treatment of pyogenic spondylodiscitis: Is it safe?

OBJECTIVE

Use of BMP in the setting of infection remains controversial. We examined the safety and effectiveness of BMP in the surgical treatment of pyogenic spondylodiscitis and compared patients who have been treated with or without BMP during surgery.

METHODS

57 patients who have undergone surgery for pyogenic spondylodiscitis after presenting to a tertiary Spine referral institution between 2011 and 2020 were included. 18 underwent surgery alone without BMP and 39 underwent surgery with BMP. Outcomes were compared between the two groups, including re-operations, infection recurrences, BMP- related complications and radiological fusion.

RESULTS

The cohort comprised 41 males (71.9%) with a mean age 63.7 +/- 13.3 years. Surgical indications include instability (n = 18), pain (n = 4), neurological deficit (n = 15) and sepsis or failure of non-operative management (n = 20). In the group who underwent surgery without BMP, there were two cases of re-operation for infection recurrence (11.1%) and three cases of cage subsidence; 80% achieved definitive and probable fusion. In the group who underwent surgery with BMP, there were three cases of re-operation for infection recurrence (7.7%), three cases of cage subsidence and one case of BMP- related radiculitis; 96.5% achieved definitive and probable fusion.

CONCLUSIONS

The use of BMP in the surgical treatment of pyogenic spondylodiscitis did not confer an increased risk of infection recurrence, revision surgery or radiculitis. BMP can be a useful and safe adjunct in surgical intervention for pyogenic spondylodiscitis.

Radiographic Features Associated With Increased Surgical Invasiveness in Pyogenic Vertebral Column Osteomyelitis

STUDY DESIGN

Single center retrospective cohort study.

OBJECTIVES

Assess the association between well-known radiographic features for spinal instability from the Spinal Instability in Neoplasia Score (SINS) and surgical invasiveness in treating vertebral column osteomyelitis (VCO). This will potentially help surgeons in surgical planning and aid in developing a pathology specific score.

METHODS

Patients with VCO were identified from hospital coding. On preoperative computed tomography radiographic features, including spinal alignment, vertebral body collapse, location, type of bone lesion, and posterolateral involvement were assessed and scored 0 (stable) to 15 (highly unstable). Surgical invasiveness was graded as 0 = no surgery, 1 = decompression alone, 2 = shortening or posterior stabilization, or 3 = anterior column reconstruction.

RESULTS

A total of 41 patients were included. The mean age of the cohort was 63.3 years (SD 12.0) with male comprising 78%. The mean total radiographic score for the nonsurgical group was 6.39 (3.14) and for the surgical group 10.38 (3.06), P < .001. Spinal alignment, vertebral body collapse, type of bone lesion, and posterolateral involvement correlated with surgical invasiveness (all Ps < .05). Subgroup comparison following analysis of variance showed that only spinal alignment was significantly different between groups 2 and 3.

CONCLUSIONS

Our findings show correlation of the radiographic components of the SINS with surgical invasiveness in management of pyogenic VCO-these findings should aid development of an "instability score" in pyogenic VCO. While most radiographic features assessed correlated with surgical invasiveness spinal alignment appears to be the key feature in determining the need for more invasive surgery.

Insights into complication rates, reoperation rates, and healthcare utilization associated with use of recombinant human bone morphogenetic protein–2 in patients with spine infections

OBJECTIVE

Use of recombinant human bone morphogenetic protein–2 (rhBMP-2) in patients with spine infections is controversial. The purpose of this study was to identify long-term complications, reoperations, and healthcare utilization associated with rhBMP-2 use in patients with spine infections.

METHODS

This retrospective study extracted data using ICD-9/10 and CPT codes from MarketScan (2000–2016). Patients were dichotomized into 2 groups (rhBMP-2, no rhBMP-2) based on whether rhBMP-2 was used during fusion surgery for spinal infections. Outcomes of interest were reoperation rates (index level, other levels), readmission rates, discharge disposition, length of stay, complications, and healthcare resource utilization at the index hospitalization and 1, 3, 6, 12, and 24 months following discharge. Outcomes were compared using nonparametric 2-group tests and generalized linear regression models.

RESULTS

The database search identified 2762 patients with > 24 months’ follow-up; rhBMP-2 was used in 8.4% of their cases. The patients’ median age was 53 years, 52.43% were female, and 15.11% had an Elixhauser Comorbidity Index ≥ 3. Patients in the rhBMP-2 group had higher comorbidity indices, incurred higher costs at index hospitalization, were discharged home in most cases, and had lower complication rates than those in the no–rhBMP-2 group. There was no statistically significant between-groups difference in complication rates 1 month following discharge or in reoperation rates at 3, 6, 12, and 24 months following the procedure. Patients in the no–rhBMP-2 group incurred higher utilization of outpatient services and medication refill costs at 1, 3, 6, 12, and 24 months following surgery.

CONCLUSIONS

In patients undergoing surgery for spine infection, rhBMP-2 use was associated with lower complication rates and higher median payments during index hospitalization compared to cases in which rhBMP-2 was not used. There was no significant between-groups difference in reoperation rates (index and other levels) at 3, 6, 12, and 24 months after the index operation. Patients treated with rhBMP-2 incurred lower utilization of outpatient services and overall payments. These results indicate that rhBMP-2 can be used safely in patients with spine infections with cost-effective utilization of healthcare resources and without an increase in complications or reoperation rates.

Thoracic Epidural Abscesses: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

Past research has demonstrated increased speed and severity of progression for spinal epidural abscesses (SEAs) of the thoracic level, specifically, when compared with SEAs of other spinal cord levels. Untreated, this infection can result in permanent neurological sequelae with eventual progression to death if inadequately managed. Despite the seriousness of this disease, no articles have focused on the presentation, diagnosis, and treatment of SEAs of the thoracic level. For this reason, specific focus on SEAs of the thoracic level occurred when researchers designed and implemented the following systematic review.

METHODS

A query of Ovid-Medline and EMBASE, Cochrane Central, and additional review sources was conducted. Search criteria focused on articles specific to thoracic epidural abscesses.

RESULTS

Twenty-five articles met inclusion criteria. The most commonly reported symptoms present on admission included back pain, paraparesis/paraplegia, fever, and loss of bowel/bladder control. Significant risk factors included diabetes, intravenous drug use, and advanced age (P = .001). Patients were most often treated surgically with either laminectomy, hemilaminectomy, or radical decompression with debridement. Patients who presented with neurological deficits and had delayed surgical intervention following a failed antibiotic course tended to do worse compared with their immediate surgical management counterparts (P < .005).

CONCLUSIONS

For the first time researchers have focused specifically on SEAs of the thoracic level, as opposed to previously published general analysis of SEAs as a whole. Based on the results, investigators recommend early magnetic resonance imaging of the spine, laboratory workup (sedimentation rate/C-reactive protein, complete blood count), abscess culture followed by empiric antibiotics, and immediate surgical decompression when neurological deficits are present.

Comparison of Expandable and Fixed Interbody Cages in a Human Cadaver Corpectomy Model: Fatigue Characteristics

STUDY DESIGN

In vitro cadaver biomechanics study.

OBJECTIVE

The goal of this study is to compare the in situ fatigue life of expandable versus fixed interbody cage designs.

SUMMARY OF BACKGROUND DATA

Expandable cages are becoming more popular, in large part, due to their versatility; however, subsidence and catastrophic failure remain a concern. This in vitro analysis investigates the fatigue life of expandable and fixed interbody cages in a single level human cadaver corpectomy model by evaluating modes of subsidence of expandable and fixed cages as well as change in stiffness of the constructs with cyclic loading.

METHODS

Nineteen specimens from 10 human thoracolumbar spines (T10-L2, L3-L5) were biomechanically evaluated after a single level corpectomy that was reconstructed with an expandable or fixed cage and anterior dual rod instrumentation. All specimens underwent 98 K cycles to simulate 3 months of postoperative weight bearing. In addition, a third group with hyperlordotic cages was used to simulate catastrophic failure that is observed in clinical practice.

RESULTS

Three fixed and 2 expandable cages withstood the cyclic loading despite perfect sagittal and coronal plane fitting of the endcaps. The majority of the constructs settled in after initial subsidence. The catastrophic failures that were observed in clinical practice could not be reproduced with hyperlordotic cages. However, all cages in this group subsided, and 60% resulted in endplate fractures during deployment of the cage.

CONCLUSIONS

Despite greater surface contact area, expandable cages have a trend for higher subsidence rates when compared with fixed cages. When there is edge loading as in the hyperlordotic cage scenario, there is a higher risk of subsidence and intraoperative fracture during deployment of expandable cages.

Oblique corpectomy for treatment of cervical spine epidural abscesses: Report on four cases

BACKGROUND

Spinal epidural abscesses (SEAs) in cervical locations are particularly life-threatening. Currently, SEAs are widely treated with bony decompression, followed by internal stabilization in purulent osteomyelitis. However, recently, a growing number of studies have reported minimally invasive approaches without internal fixation.

PURPOSE

We describe four patients with cervical SEAs that were evacuated by oblique corpectomy (OC) without fusion.

METHODS

This study included two women and two men (aged 44-90) that received operations for removing ventral cervical SEAs. All patients presented with progressively increasing myelopathy, and 3 had severe comorbid conditions. In all cases, a multilevel OC without fusion was performed. The amount of bone resection was tailored to fit the needs of granulation removal, with an effort to retain as much of the vertebral bodies as possible. Then, pus was evacuated and debridement of granulation was performed, followed by rinsing and drainage.

RESULTS

The neurological status of 3 patients improved significantly after surgery. At the last follow-up examination, one showed full recovery, and in two a minor residual deficit persisted. During mean follow-up of 5.5 years, no internal stabilization was necessary. The oldest patient was tetraplegic, and had several concomitant diseases. That patient died from sudden cardiac arrest on the third postoperative day. Oblique corpectomy did not affect the anterior or posterior column. Additionally, it provided a broad view of the ventral aspect of the spinal canal.

CONCLUSIONS

Oblique corpectomy allows appropriate spinal cord decompression and granulation removal in the case of cervical spine epidural abscess, without sacrificing spinal stability.

Bone substitutes and expanders in Spine Surgery: A review of their fusion efficacies

STUDY DESIGN

A narrative review of literature.

OBJECTIVE

This manuscript intends to provide a review of clinically relevant bone substitutes and bone expanders for spinal surgery in terms of efficacy and associated clinical outcomes, as reported in contemporary spine literature.

SUMMARY OF BACKGROUND DATA

Ever since the introduction of allograft as a substitute for autologous bone in spinal surgery, a sea of literature has surfaced, evaluating both established and newly emerging fusion alternatives. An understanding of the available fusion options and an organized evidence-based approach to their use in spine surgery is essential for achieving optimal results.

METHODS

A Medline search of English language literature published through March 2016 discussing bone graft substitutes and fusion extenders was performed. All clinical studies reporting radiological and/or patient outcomes following the use of bone substitutes were reviewed under the broad categories of Allografts, Demineralized Bone Matrices (DBM), Ceramics, Bone Morphogenic proteins (BMPs), Autologous growth factors (AGFs), Stem cell products and Synthetic Peptides. These were further grouped depending on their application in lumbar and cervical spine surgeries, deformity correction or other miscellaneous procedures viz. trauma, infection or tumors; wherever data was forthcoming. Studies in animal populations and experimental in vitro studies were excluded. Primary endpoints were radiological fusion rates and successful clinical outcomes.

RESULTS

A total of 181 clinical studies were found suitable to be included in the review. More than a third of the published articles (62 studies, 34.25%) focused on BMP. Ceramics (40 studies) and Allografts (39 studies) were the other two highly published groups of bone substitutes. Highest radiographic fusion rates were observed with BMPs, followed by allograft and DBM. There were no significant differences in the reported clinical outcomes across all classes of bone substitutes.

CONCLUSIONS

There is a clear publication bias in the literature, mostly favoring BMP. Based on the available data, BMP is however associated with the highest radiographic fusion rate. Allograft is also very well corroborated in the literature. The use of DBM as a bone expander to augment autograft is supported, especially in the lumbar spine. Ceramics are also utilized as bone graft extenders and results are generally supportive, although limited. The use of autologous growth factors is not substantiated at this time. Cell matrix or stem cell-based products and the synthetic peptides have inadequate data. More comparative studies are needed to evaluate the efficacy of bone graft substitutes overall.

Multilevel Corpectomy With Anterior Column Reconstruction and Plating for Subaxial Cervical Osteomyelitis

STUDY DESIGN

A retrospective case series.

OBJECTIVE

The aim of this study was to evaluate patients with cervical spine osteomyelitis who underwent multilevel (≥2) subaxial corpectomies and anterior column reconstruction and plating.

SUMMARY OF BACKGROUND DATA

Neglected multilevel subaxial cervical osteomyelitis is a potentially dangerous disease. As it is rare, early radiographic and clinical outcomes after multilevel anterior corpectomy and reconstruction for subaxial cervical osteomyelitis are incompletely defined.

METHODS

Adults who underwent multilevel corpectomy and anterior plating/reconstruction for subaxial cervical osteomyelitis at two institutions were reviewed. Analysis of patient demographics, operative details, and radiographic cervical alignment parameters [segmental kyphosis, cervical lordosis, C2-7 sagittal vertical axis (SVA)] was performed.

RESULTS

Nineteen patients [15 males, four females; average age 48 years (20-81 yrs)] met inclusion criteria. The majority had pre-operative neurologic deficits or was immunosuppressed. All were treated with ≥6 weeks of intravenous antibiotics following operation. All had anterior plating/reconstruction with titanium cages (expandable-6; mesh-6) or structural bone graft (fibular allogaft-6; tricortical iliac crest-1). The average number of corpectomies was 2.4 (2-4). The average numbers of levels fused anteriorly was 4.4 (4-6) and posteriorly was 6.3 (4-9). The majority of patients (74%) was treated with an anterior/posterior approach. Average follow-up was 16 ± 9 months. There was significant improvement in all cervical alignment parameters (segmental kyphosis, C2-7 SVA, cervical lordosis). No intraoperative complications occurred and no patient deteriorated neurologically postoperatively. Postoperative complications included anterior cage/graft dislodgement (n = 2), recurrent neck hematomas requiring revision (n = 1), epidural hematoma (n = 1), and wound infection (n = 1). Sixty percent of patients had persistent neurologic dysfunction at final follow-up. None required reoperation for recurrent infection or pseudarthrosis.

CONCLUSION

Although overall prognosis and neurologic recovery are guarded in medically fragile patients with multilevel subaxial cervical osteomyelitis, reconstruction with multilevel (≥2) corpectomy and anterior reconstruction/plating results in excellent restoration of cervical alignment and low rates of recurrent infection and pseudarthrosis.

LEVEL OF EVIDENCE

4.

Suitability of carbon fiber–reinforced polyetheretherketone cages for use as anterior struts following corpectomy

OBJECTIVE

Fibular allograft remains a widely used strut for corpectomy surgeries. The amount of graft material that can be packed into an allograft strut has not been quantified. Cages are an alternative to fibular allograft for fusion surgeries. The authors of this study assessed the suitability of carbon fiber–reinforced polyetheretherketone (CFRP) cages for anterior corpectomy surgeries. They further explored the parameters known to affect fusion rates in clinical practice.

METHODS

Six fibular allografts were tested at standard lengths. Three sets of carbon fiber cages (Bengal, DePuy Spine), each with a different footprint size but the same lengths, were tested. The allografts and cages were wrapped in adhesive, fluid-tight transparent barriers and filled with oil. The volume and weight of the oil instilled as well as the implant footprints were measured. The fibular allografts and cages were tested at 20-, 40-, and 50-mm lengths. Two investigators independently performed all measurements 5 times. Five CFRP cubes (1 × 1 × 1 cm) were tested under pure compression, and load versus displacement curves were plotted to determine the modulus of elasticity.

RESULTS

Significantly more oil fit in the CFRP cages than in the fibular allografts (p < 0.0001). The weight and volume of oil was 4–6 times greater in the cages. Interobserver (r = 0.991) and intraobserver (r = 0.993) reliability was excellent. The modulus of elasticity for CFRP was 16.44 ± 2.07 GPa.

CONCLUSIONS

Carbon fiber–reinforced polyetheretherketone cages can accommodate much more graft material than can fibular allografts. In clinical practice, the ability to deliver greater amounts of graft material following a corpectomy may improve fusion rates.

Mesh cage for treatment of hematogenous spondylitis and spondylodiskitis. How safe and successful is its use in acute and chronic complicated cases? A systematic review of literature over a decade

BACKGROUND

Surgical treatment of hematogenous pyogenic spondylitis and spondylodiskitis includes anterior debridement, stabilization, and fusion. Titanium mesh cage (TMC) has been advocated to immediately correct deformity and eradicate infection with low recurrence rates. There are no comprehensive reviews on TMC.

PURPOSE

To evaluate recorded information regarding surgical outcome with the use of TMC for treating patients with pyogenic spinal infection.

STUDY DESIGN

Comprehensive review.

METHODS

The terms "titanium cage", "spine", "infection" were searched. A total of 486 peer-reviewed papers published from 2002 to 2012 were obtained from PubMed search. Fifteen Level IV articles with 363 patients were enrolled for consideration. Finally, 192 (53 %) patients who received TMC were eligible and included in this review. Age, comorbidities, indications for surgery, abscess formation, time lapsed between symptoms initiation and surgery, microbiology, radiological spine restoration, neurological outcome, and complications following surgery are evaluated.

RESULTS

The average age at the index surgery was 57 years, range 15-85 years. The reported time lapsed from symptoms presentation to diagnosis varied significantly from 1 week to 2 years. On admission, there reported paravertebral and/or epidural abscess in 48 % and neurological impairment in 51 % of the patients. One hundred and seventy-seven comorbidities were recorded in 192 patients. Bone biopsy and culture revealed gram (+) bacteria in 71 %, gram (-) in 24 %, and multiple bacteria in 1 %, while it was negative in 3.1 % of the patients. TMC was most commonly (49 %) implanted in the lumbar spine. The follow-up observation following surgery averaged 26 months, range 10-116 months. Most of the studies reported decrease in segmental kyphosis and neurological improvement in incomplete lesions postoperatively. TMC was primarily revised for early dislodgment or cage misplacement in 3.2 % of the patients. Infection recurrence was recorded in two patients (1.3 %), but revision surgery needed in one (0.65 %) patient. Mortality was reported in 5.8 % of the patients.

CONCLUSIONS

TMC offers an advantageous and safe technique for spinal debridement and fusion for hematogenous spinal infection. TMC safeguarded medium-term spinal stability with low infection recurrence rates, which were independent form causative pathogen, age, and comorbidities.

Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep

STUDY DESIGN

Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft.

OBJECTIVE

The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively.

SUMMARY OF BACKGROUND DATA

Vertebral reconstruction with corpectomy devices requires bone graft. Bone graft substitutes have the potential to avoid a second operation, donor site pain, and attendant morbidity associated with autograft.

METHODS

Twenty-four sheep in 6 treatment groups underwent lumbar corpectomy via a retroperitoneal trans-psoas approach. Spines were reconstructed with autograft, rhBMP-2 on a CRM, or rhBMP-2 on an ACS mixed with ceramic granules. Grafting materials were placed in either a titanium mesh or PEEK conduit in spines with internal fixation. Computed tomographic (CT) scans were evaluated for fusion. Undecalcified histology was used to evaluate for fusion as well as the amount and extent of graft incorporation and graft resorption.

RESULTS

Regardless of corpectomy device used, rhBMP-2/CRM or rhBMP-2/ACS with MASTERGRAFT resulted in a 100% fusion rate. The autograft group had a lower (75%) radiographic fusion rate. Using either preparation of rhBMP-2 resulted in the length of the defect filling with solid bone. Autograft fragments and ceramic granules were incorporated into the fusion masses with much of the ceramic granules being resorbed by 6 months.

CONCLUSION

Both of the rhBMP-2 formulations have the potential to effect bony fusion and vertebral reconstruction within the corpectomy devices.

Fungal Infections of the Spine

STUDY DESIGN

Review of the literature.

OBJECTIVE

To retrospectively examine the frequency of published fungal infections by species and the treatment algorithms used to eradicate the disease.

SUMMARY OF BACKGROUND DATA

Fungal infections of the spine present unique challenges to the modern multispecialty treatment team. Although rare in comparison with bacterial infections, fungal infections have been increasing in incidence over the past several decades. Evidences-based practice is limited to referencing smaller case series.

METHODS

MEDLINE, Scopus, and EMBASE searches were carried out by one of the authors as well as by the research desk at the University of Miami/Calder Memorial Library. We included peer-reviewed articles published between 1948 and September 2010; case reports, series, and reviews were all examined and compiled into a database.

RESULTS

A total of 130 articles, representing 157 cases, were included in the review. Aspergillus (60 cases, 38.2% of the total) and Candida species (36 cases, 22.9% of the total) were the 2 most common organisms. Surgery was associated with a greater survival rate than medical management alone in patients with Aspergillus (26.9% mortality in surgical patients; 60% in medically treated patients) and Candida (0% vs. 28.6%). Overall mortality was 19.3%. The overall recurrence rate was 7.4%. Amphotericin use was associated with a higher mortality rate than azoles.

CONCLUSION

Aspergillus is the most common published pathogen in fungal infections of the spine. Recent publications depicting the use of newer antifungal medications such as azoles report higher survival rates. Surgically treated patients in combination with antifungal therapy showed highest frequencies of patient survival in Aspergillus and Candida infections.

LEVEL OF EVIDENCE

3.

Complications, revision fusions, readmissions, and utilization over a 1-year period after bone morphogenetic protein use during primary cervical spine fusions

BACKGROUND CONTEXT

Nationwide estimates examining bone morphogenetic protein (BMP) use with cervical spine fusions have been limited to perioperative outcomes.

PURPOSE

To determine the 1-year risk of complications, cervical revision fusions, hospital readmissions, and health care services utilization.

STUDY DESIGN

A retrospective cohort study from 2002 to 2009 using a nationwide claims database.

PATIENT SAMPLE

There were 61,937 primary cervical spine fusions of which 1,677 received BMP.

OUTCOME MEASURES

Complications, revision fusions, 30-day hospital readmission, and health care utilization.

METHODS

Data for these analyses come from the Thomson Reuters MarketScan Commercial Claims and Encounters Database 2010. Patients were aged 18 to 64 years, receiving and not receiving BMP with a primary (C2-C7) cervical spine fusion. All outcomes were defined by International Classification of Diseases, 9th edition Clinical Modification and Current Procedural and Terminology, 4th edition codes. Complications were analyzed as any complication and stratified by nervous system, wound, and dysphagia or hoarseness. Cervical revision fusions were determined in the 1-year follow-up. Hospital readmission discharge records defined 30-day hospital readmission and reason for the readmission. The utilization of at least one health care service of cervical spine imaging, epidural usage or rehabilitation service was examined. Poisson regression models were used to estimate the relative risk and 95% confidence interval (CI). Linear regression was used to determine the time to hospital readmission. Results were stratified by anterior or posterior and circumferential approaches.

RESULTS

Patients receiving BMP were 29% more likely to have a complication (adjusted relative risk [aRR]=1.29 [95% CI, 1.14-1.46]) and a nervous system complication (aRR=1.42 [95% CI, 1.10-1.83]). Cervical revision fusions were more likely among patients receiving BMP (aRR=1.69 [95% CI, 1.35-2.13]). The risk of 30-day readmission was greater with BMP use (aRR=1.37 [95% CI, 1.07-1.73]) and readmission occurred 27.4% sooner on an average. Patients receiving BMP were more likely to receive computed tomography scans (aRR=1.34 [95% CI, 1.06-1.70]) and epidurals with anterior surgical approaches (aRR=1.29 [95% CI, 1.00-1.65]).

CONCLUSIONS

These findings question both the safety and effectiveness of off-label BMP use in primary cervical spine fusions.

A consensus statement regarding the utilization of BMP in spine surgery

Recombinant human bone morphogenetic protein - 2 (rh-BMP-2) was first approved by the United States Food and Drug Administration (FDA) in 2002 for use in anterior lumbar interbody fusions. Since that time, it has been estimated that "off label" use accounts for 85 % of applications. Original, industry sponsored studies demonstrated superior fusion rates with decreased incidence of complications when compared with traditional iliac crest bone graft. These studies have been criticized for potential bias and newer research has detailed potential complications as well as alternative applications. Potential off label uses of rhBMP-2 include: anterior lumbar fusions, single level posterior lumbar fusions, multiple level posterior lumbar fusions, posterior cervical fusions, long deformity fusions, in the presence of vertebral osteomyelitis, and in patients with history of malignancy. A review of the literature related to rhBMP-2 was conducted to evaluate its use for the above-mentioned applications with a special focus on fusion rates, observed complications, and clinical or radiographic outcomes.

Comparison of expandable and fixed interbody cages in a human cadaver corpectomy model, Part I: endplate force characteristics

Object

Expandable cages are becoming more popular due in large part to their versatility, but subsidence and catastrophic failure remain a concern. One of the proposed reasons of failure is edge loading of the endplate caused by a mismatch between the sagittal alignment of the motion segment and cage. This in vitro analysis investigates the endplate forces characteristic of expandable and fixed interbody cages in a single-level human cadaver corpectomy model.

Methods

Ten human thoracolumbar spines (T10–L2, L3–5) were biomechanically evaluated following a single-level corpectomy that was reconstructed with an expandable or fixed cage. Fixed cages were deployed with the best-fitting end cap combination, whereas expandable cages were deployed in normal, hypolordotic, and hyperlordotic alignment scenarios. The endplate forces and contact area were measured with a pressure measurement system, and the expansion torque applied by the surgeon was measured with a custom-made insertion device.

Results

The contact areas of the expandable cages were, in general, higher than those of the fixed cages. The endplate forces of the expandable cages were similar to those of the fixed cages in the normal alignment scenario. Higher endplate forces were observed in the hyperlordotic scenario, whereas the endplate forces in the hypolordotic and normal alignment scenarios were similar. There was no correlation with the expansion torque and the final endplate forces.

Conclusions

Expandable cages resulted in consistently higher contact area and endplate forces when compared with the fixed cages. Because the expansion torque does not correlate with the final endplate forces, surgeons should not rely solely on tactile feedback during deployment of these cages.

Can a novel rectangular footplate provide higher resistance to subsidence than circular footplates? An ex vivo biomechanical study

STUDY DESIGN

Ex vivo biomechanical evaluation using cadaveric vertebral bodies.

OBJECTIVE

To compare the subsidence characteristics of a novel rectangular footplate design with a conventional circular footplate design.

SUMMARY OF BACKGROUND DATA

Cage subsidence is a postoperative complication after reconstruction of corpectomy defects in the thoracolumbar spine and depends on factors, such as bone quality, adjunctive fixation, and the relationship between the footplate on the cage and the vertebral body endplate.

METHODS

Twenty-four cadaveric vertebrae (T12-L5) were disarticulated, potted in a commercial resin, loaded with either a circular or a rectangular footplate, and tested in a servo hydraulic testing machine. Twelve vertebral bodies were loaded with a circular footplate, and after subsidence the same vertebral bodies were loaded with a rectangular footplate. The second set of 12 vertebral bodies was loaded with a rectangular footplate only. Force-displacement curves were developed for the 3 groups, and the ultimate load to failure and stiffness values were calculated.

RESULTS

The ultimate load to failure with the circular footplate was 1310 N (SD, 482). The ultimate load to failure with a rectangular footplate with a central defect and without a central defect was 1636 N (SD, 513) and 2481 N (SD, 1191), respectively. The stiffness of the constructs with circular footplate was 473 N/mm (SD, 205). The stiffness of the constructs with a rectangular footplate with a central defect and without a central defect was 754 N/mm (SD, 217) and 1054 N/mm (SD, 329), respectively.

CONCLUSION

A rectangular footplate design is more resistant to subsidence than a circular footplate design in an ex vivo biomechanical model. The new design had higher load to failure even in the presence of a central defect. These findings suggest that rectangular footplates may provide better subsidence resistance when used to reconstruct defects after thoracolumbar corpectomy.

Candida osteomyelitis: analysis of 207 pediatric and adult cases (1970-2011)

BACKGROUND

The epidemiology, pathogenesis, clinical manifestations, management, and outcome of Candida osteomyelitis are not well understood.

METHODS

Cases of Candida osteomyelitis from 1970 through 2011 were reviewed. Underlying conditions, microbiology, mechanisms of infection, clinical manifestations, antifungal therapy, and outcome were studied in 207 evaluable cases.

RESULTS

Median age was 30 years (range, ≤ 1 month to 88 years) with a >2:1 male:female ratio. Most patients (90%) were not neutropenic. Localizing pain, tenderness, and/or edema were present in 90% of patients. Mechanisms of bone infection followed a pattern of hematogenous dissemination (67%), direct inoculation (25%), and contiguous infection (9%). Coinciding with hematogenous infection, most patients had ≥2 infected bones. When analyzed by age, the most common distribution of infected sites for adults was vertebra (odds ratio [OR], 0.09; 95% confidence interval [CI], .04-.25), rib, and sternum; for pediatric patients (≤18 years) the pattern was femur (OR, 20.6; 95% CI, 8.4-48.1), humerus, then vertebra/ribs. Non-albicans Candida species caused 35% of cases. Bacteria were recovered concomitantly from 12% of cases, underscoring the need for biopsy and/or culture. Candida septic arthritis occurred concomitantly in 21%. Combined surgery and antifungal therapy were used in 48% of cases. The overall complete response rate of Candida osteomyelitis of 32% reflects the difficulty in treating this infection. Relapsed infection, possibly related to inadequate duration of therapy, occurred among 32% who ultimately achieved complete response.

CONCLUSIONS

Candida osteomyelitis is being reported with increasing frequency. Localizing symptoms are usually present. Vertebrae are the most common sites in adults vs femora in children. Timely diagnosis of Candida osteomyelitis with extended courses of 6-12 months of antifungal therapy, and surgical intervention, when indicated, may improve outcome.

Spondylodiscitis: standards of current treatment

BACKGROUND

Spinal infections are an important clinical problem that often require aggressive medical therapy, and sometimes even surgery. Known risk factors are advanced age, diabetes mellitus, rheumatoid arthritis, immunosuppression, alcoholism, long-term steroid use, concomitant infections, poly-trauma, malignant tumor, and previous surgery or invasive procedures (discography, chemonucleolysis, and surgical procedures involving or adjacent to the intervertebral disc space). The most common level of involvement is at the lumbar spine, followed by the thoracic, cervical and sacral levels: lesions at the thoracic spine tend to lead more frequently to neurological symptoms.

OBJECTIVE

The aim of the current paper is to describe current evidence-based standards of therapy in the management of SD by emphasizing pharmacological therapy and principles and indications for bracing and surgery.

METHODS

A PubMed and Google Scholar search using various forms and combinations of the key words: spondylodiscitis, spine, infection, therapy, surgery, radiology, treatment. Reference citations from publications identified in the literature search were reviewed. Publications highlighted in this article were extracted based on relevancy to established, putative, and emerging diagnostic and therapeutic standards, either conservative (antibiotic therapy and bracing) or surgical.

FINDINGS

To date, conservative therapy, based on targeted antibiotic therapy plus bracing, represents the mainstay in the management of SD. Proper diagnosis and tailored therapy can improve clinical results and decrease the chance of failure. Surgery should be an option only for patients with complications of this disease, namely deformity, neural compression and neurological compromise. Current standards in the setting of SD are continuously evolving, as can be seen in the recent advances in the field of radiological diagnostics, and the use of growth factors and cell-therapy strategies to promote infection eradication and bone healing after surgery.

Primary pyogenic infection of the spine in intravenous drug users: a prospective observational study

STUDY DESIGN

A prospective comparative analysis of surgically-treated nontuberculous primary pyogenic infection of the spine (PPIS).

OBJECTIVE

To evaluate and compare the demographics, presentation, treatment and outcomes of surgically-treated PPIS between intravenous drug users (IVDU) and non-IVDU patients.

SUMMARY OF BACKGROUND DATA

This is the first prospective cohort comparative analysis of the clinical outcomes of surgically-treated PPIS between IVDU and non-IVDU populations. This is also the largest cohort of consecutive surgically-treated PPIS in a population of IVDU.

METHODS

Data on all patients with PPIS presenting to a quaternary referral center during a 4-year period from 2004 were collected in a prospectively maintained customized database.

RESULTS

During the study period there were 102 patients treated for PPIS of which 51 were IVDU. Of this IVDU group, the mean age was 43 years (range: 25-57). Twenty-three had human immunodeficiency virus, 43 had hepatitis C, and 13 had hepatitis B. All were using cocaine, 26 were also using heroin and 44 were using at least 3 recreational drugs. Thirty patients presented with axial pain of a mean duration of 51 days (range: 3-120 days). Of the IVDU patients with neurological deficit on presentation, the mean American Spinal Injury Association (ASIA) motor score was 58.6. The most common ASIA motor levels involved were C4 and C5. Mean duration of neurological symptoms was 7 days (range: 1-60 days). Twenty-six were already receiving i.v. antibiotics for known spinal infection and 33 patients had an identifiable organism on blood cultures (19 methicillin-sensitive Staphylococcus aureus, 9 methicillin-resistant S. aureus). Forty-four of the 51 IVDU patients were treated surgically. Thirty-four of the 44 surgically treated cases involved the cervical spine. Twenty-two had a posterior approach alone, 13 had anterior only while 9 required combined anterior and posterior approaches at the index surgery. Seven required early revision for hardware failure (none of whom has combined approach) and 2 developed a postoperative surgical site infection (SSI). Thirty-seven of the 51 IVDU patients were apprehended at least once using illicit drugs while in hospital. Mean duration of antibiotic treatment after surgery was 62 days. At discharge, 28 of 44 patients had neurological improvement (mean = 20 ASIA points, range: 1-55), 11 had neurological deterioration during treatment (mean = 13, range = 1-50), and 5 were unchanged. Among the IVDUs there were no in-hospital deaths. At 2 years after index admission 13 IVDU patients were dead, and none were attending for follow-up despite all efforts to locate the patients. In the non-IVDU group, the mean age of the 51 patients was 56 years (range 25-83). Thirty-four patients presented with axial pain with a mean duration of 105 days (range 2-365). Mean ASIA motor score of patients with neurological deficit on admission was 74. Most common ASIA level was T12. Mean duration of neurological symptoms was 12 days (range 1-84). Thirteen patients were receiving i.v. antibiotics for known spinal infection and 20 patients had an identifiable organism on blood culture (30% methicillin-sensitive S. aureus, 50% methicillin-resistant S. aureus). Forty-four of these 51 non-IVDU patients were treated surgically. Thirty-five of the 44 surgically-treated cases involved the thoracic or lumbar spines. Twenty-nine had a posterior approach alone, 3 had anterior alone while 12 required combined approaches. No early hardware failures were seen in the non-IVDU group while 4 developed SSI. Mean duration of antibiotic treatment after surgery was 45 days. At discharge 21 patients had neurological improvement (mean 9 ASIA points, range: 1-17). Five had neurologic deterioration with a mean motor loss of 16 points (10-23). There were 4 in-hospital deaths among the non-IVDU group. At 2 years after index admission, 19 patients were dead and the remainder were all available for follow-up.

CONCLUSION

There are significant differences in demographics, presentation, treatment and outcomes of primary spinal pyogenic infection between a population of IVDU and a comparable cohort of non-IVDU. The IVDU group presents with cervical quadriplegia while it is the thoracolumbar spine that is almost exclusively involved in the non-IVDU group. Among the IVDUs, surgical management is complex with a high incidence of early hardware failure. SSI is significantly more common among non-IVDU. Significant neurological improvement can be expected in the majority of IVDU patients with a high mortality rate among the non-IVDU. IVDU are unreliable patients and in-hospital, in-halo incarceration is recommended where possible.

Advances on the Masquelet technique using a cage and nail construct

Traumatic, cancerous or infectious loss of bone is treated by either amputation or reconstruction. With limb salvage always preferable, surgeons rely on already established techniques such as grafting and distraction osteogenesis to avoid amputation, and ideally restore structure and thus function. The Masquelet technique is an effective method of bone reconstruction and limb salvage which is underreported in the English literature, and we report a case with advances using a cage and nail construct, resulting in successful eradication of methicillin resistant staphylococcus aureus infection and reconstitution of a 17 cm diaphyseal defect in the tibia.

[Thoracic spine pseudarthrosis treated by transpleural corporectomy and bone morphogenic protein]

BACKGROUND AND PURPOSE

Traumatic thoracic spine instability is a rare but difficult-to-treat entity, particularly above T5 where pedicle screwing is widely regarded as an unsatisfactory option and anterior surgery is considered difficult because of the anatomic relationship with the shoulder and large vessels.

METHODS

A case of T4 and T5 pseudarthrosis after posterior fixation is reported. It was treated with transpleural corpectomy and fixation, with bone morphogenic protein used to obtain rapid arthrodesis between T3 and T6. No bracing or second posterior fixation was used.

RESULT

At 45 days of follow-up, the patient was without pain and the neurologic examination was normal. The CT scan showed bony bridges across all fracture lines. Complete cure of this pseudarthrosis was achieved with a single surgery. At the 12-month follow-up, the clinical status was normal.

CONCLUSIONS

The use of bone morphogenic proteins might be of great help in rare but challenging cases of spinal pseudarthrosis, with a quick return to normal activity after a single-stage surgery.

Analysis of prevertebral soft-tissue swelling and dysphagia in multilevel anterior cervical discectomy and fusion with recombinant human bone morphogenetic protein-2 in patients at risk for pseudarthrosis

OBJECT

The goal of this study was to demonstrate the incidence of fusion and soft-tissue swelling in multilevel anterior cervical discectomies and fusions (ACDFs) using polyetheretherketone (PEEK) spacers with recombinant human bone morphogenetic protein-2 (rhBMP-2) impregnated in a Type I collagen sponge and titanium plates.

METHODS

A single surgeon performed 30 multilevel ACDFs using PEEK spacers with an rhBMP-2 impregnated collagen sponge (0.4 ml, or the equivalent of 0.6 mg rhBMP-2). Soft-tissue swelling was assessed using cervical spine radiographs on postoperative Day 1 and at 2, 6, and 10 weeks and 6 months after surgery. Incidence of dysphagia was assessed with the Cervical Spine Research Society Swallowing-Quality of Life tool. Clinical success was evaluated with the Neck Disability Index, neck pain scores, and arm pain scores. Final fusion was assessed with CT by an independent neuroradiologist.

RESULTS

Patients were followed for 6 months unless they had an incomplete fusion; those patients were reassessed at 9 months. Twenty-four patients underwent 2-level ACDFs and 6 underwent 3-level ACDFs were performed on patients with the following risk factors for pseudarthrosis: smoking (33%), diabetes (13%), and obesity (body mass index ≥ 30 [43%]). Seventeen percent of the patients had multiple risk factors. Soft-tissue swelling peaked at 2 weeks regardless of level of surgery or number of levels treated surgically and decreased to near preoperative levels by 6 months. At 2 weeks, Swallowing-Quality of Life evaluation showed 19% of patients frequently choking on food, 4.8% frequently choking when drinking, and 47.6% with frequent food sticking in the throat. Scores continued to improve, and at 6 months, 0% had frequent choking on food, 6.7% had frequent difficulty drinking, and 6.7% had frequent food sticking in the throat. The Neck Disability Index, neck pain, and arm pain scores all improved progressively over 6 months. Incidence of fusion was 95% at 6 months and 100% at 9 months. There were no rehospitalizations or reoperations for soft-tissue swelling or dysphagia.

CONCLUSIONS

Multilevel ACDF procedures using PEEK grafts and rhBMP-2 can be performed safely in patients with multiple risk factors for pseudarthrosis with excellent fusion outcomes.

Bone morphogenetic protein binding peptide mechanism and enhancement of osteogenic protein-1 induced bone healing

STUDY DESIGN

In vitro and in vivo evaluation of BBP interactions with BMP.

OBJECTIVE

To explore bone morphogenetic protein-binding peptide (BBP)'s mechanism of action, investigate an extended repertoire for BBP applications, and evaluate the usefulness of BBP as a surgical adjuvant when used with recombinant human osteogenic protein-1 (rhOP-1).

SUMMARY OF BACKGROUND DATA

Bone morphogenetic proteins (BMPs) are osteoinductive proteins that provide a potential alternative to autograft. Their utility is limited by cost, and potential dose-dependent risks, such as local inflammatory reactions and ectopic bone formation. BBP, a cyclized synthetic peptide, avidly binds recombinant human BMP-2(rhBMP-2) and has been shown to accelerate and enhance its osteogenic qualities.

METHODS

BBP binding with 4 growth factors from the transforming growth factor -beta family were assessed using surface plasmon resonance. The in vivo retention of rhBMP-2 was quantified by comparing the percentage of retained [¹²⁵I]-labeled rhBMP-2 in absorbable collagen sponge implants with or without BBP at 1, 3, and 7 days postimplantation. The adjunctive effect of BBP with rhOP-1-induced bone growth was evaluated by comparing time to fusion and fusion rates in a rodent posterolateral fusion model with 2 different doses of rhOP-1 with or without BBP.

RESULTS

BBP bound all 4 growth factors with an intermediate affinity. The in vivo retention of rhBMP-2 alone ranged from about 40% on day 1 to about 30% on day 7, whereas, the retention of rhBMP-2 in the presence of BBP was about 85% on day 1 and about 55% on day 7. The addition of BBP to rhOP-1 resulted in significantly earlier and greater fusion rates than achieved with rhOP-1 alone.

CONCLUSION

The mechanism of the BBP enhanced osteoinductive properties of BMPs involves the binding and retention of the growth factor, resulting in a prolonged exposure of BMP to the desired fusion site. The use of BBP in conjunction with BMPs may prove to provide satisfactory fusion outcomes, while reducing the costs and side effects associated with BMP use.

Spinal reconstruction and bone morphogenetic proteins: open questions

Spinal fusion is a proven surgical tool for the treatment of degenerative, traumatic, neoplastic, and infectious conditions of the spine. Traditional grafting techniques using autogenous bone graft or allograft have inherent drawbacks including varying pseudoarthrosis rates and well recognized bone graft harvest site complications. Bone morphogenetic proteins (BMPs) offer the exciting prospect of enhanced union rates equal to or greater than autograft and potentially eliminate graft harvest site complications. Many studies have clearly demonstrated the efficacy of BMP products for various applications in spine surgery. BMP has proven effective in achieving union in anterior and posterior lumbar surgery and recently in anterior cervical surgery. Despite the reported success, the universal adoption of BMP is tempered by high costs and lingering safety concerns with reported complications specific to BMP use including vertebral osteolysis, ectopic bone formation, radiculitis and cervical soft tissue swelling. Ongoing clinical and basic-science research is focused on clearly defining guidelines for BMP use in spine surgery and on developing more affordable BMP formulations with dosing that predictably results in spine fusion yet minimizes the possible side effect profile.

Infectious Collet-Sicard syndrome in the differential diagnosis of cerebrovascular accident: a case of head-to-neck dissociation with skull-based osteomyelitis

BACKGROUND CONTEXT

Collet-Sicard syndrome (CSS) is a rare condition that includes palsies of cranial nerves IX, X, XI, and XII. There are multiple reported causes in the literature, although infection is particularly unusual.

PURPOSE

To report an unusual case of CSS as a result of infection causing head-to-neck dissociation with involvement of the upper cervical spine.

STUDY DESIGN

Case report.

METHODS

A 56-year-old male with medical comorbidities developed a cranial-based infection secondary to initial incomplete treatment of otitis media. The mass effect of the infection resulted in multiple cranial nerve palsies and extremity symptoms initially confused with a cerebrovascular accident. Clinical course of the patient and a review of CSS are presented.

RESULTS

With progression of the disease, further evaluation revealed a disseminated upper cervical and skull-based infection causing destructive head-to-neck infectious instability. This was treated with posterior occipitocervical debridement, fixation, and fusion and appropriate long-term antibiotics. Over the course of several months, the infection resolved and there was a significant improvement in his dysphagia, dysarthria, and hearing.

CONCLUSIONS

Delay in diagnosis of CSS is common, and this syndrome should be considered in patients who present with a constellation of lower cranial nerve palsies. Early recognition and treatment should result in successful recovery, but even in cases of delayed detection, suitable intervention can result in substantial clinical improvement.

The use of allograft or autograft and expandable titanium cages for the treatment of vertebral osteomyelitis

OBJECTIVE

The results of the surgical treatment of osteomyelitis with expandable titanium cages and either allograft or autograft are presented.

METHODS

Thirty-six patients with vertebral osteomyelitis are presented. There were 7 cervical, 17 thoracic, 4 thoracolumbar (involving T12-L1), 5 lumbar, and 3 lumbosacral (involving L5-S1) lesions. The most frequently identified organisms were Staphylococcus aureus, Mycobacterium tuberculosis, and Coccidioides immitis. Imaging studies included x-rays, computed tomographic scans, and magnetic resonance imaging scans. All patients were treated with corpectomies and expandable cage reconstruction. Fusion was performed with rib autograft, iliac crest autograft, or allograft. Most patients who had an anterior approach also underwent posterior instrumentation, whereas a few had anterior instrumentation only. Four patients underwent a posterior approach (transpedicular corpectomy) only.

RESULTS

The median follow-up period was 21 months. There were no implant failures. Two recurrences of infection were noted: 1 case involved allograft, and the other involved autograft. At follow-up, neurological deficits improved in all patients, and 81% of patients were pain-free.

CONCLUSION

This study suggests that the treatment of vertebral column osteomyelitis can be performed with expandable titanium cages, and allograft does not appear to increase the rate of recurrence, as compared with autograft.

Reconstruction of large defects in vertebral osteomyelitis with expandable titanium cages

The purpose of this study was to investigate the outcome of expandable titanium cage implantation in large defects caused by acute vertebral osteomyelitis. Twenty-five patients with acute single or multilevel spondylodiscitis were treated after radical débridement and posterior instrumentation with an anterior expandable titanium cage and bone grafting. Clinical, laboratory and radiological follow-up continued for 36 months. Within the postoperative course there was no recurrence of spinal infection. The final radiological examination showed successful fusion in all cases without implant loosening or failure. At the final follow-up after 36 months the Oswestry Disability Index was 23 +/- 14 and the pain visual analogue scale 2.1 +/- 1.7. This study reveals healing and improved function after expandable titanium cage implantation in all patients. Prerequisites for optimal healing include radical débridement, provision of stability for weight-bearing, adequate bone grafting and correction of deformity using rigid implants.

[Anterior cervical fusion in the lower cervical spine. Locked vs nonlocked screw plate, pure cancellous bone vs tricortical strut]

Physical alterations in cervical fusions endanger healing. Experimentally we determined less stability loss in fixations using cancellous bone grafts than in those using tricortical grafts. Four hundred eighty-five Patients underwent anterior cervical fusion, for a total of 700 Segments. Patients were divided into four groups: (1) nonlocked H plate with autogenous cancellous bone, (2) nonlocked H plate with autogenous tricortical graft, (3) locked cervical plate with tricortical graft, and (4) stand-alone cage with cancellous bone. Evaluations included X-ray and random CT scan examinations. Our results suggest that anterior cervical fusions using nonlocked H screw plate systems with pure autogenous cancellous bone grafts provide the fastest (6 weeks) and most secure bone healing (P=0.00001), whereas fixations using nonlocked or locked screw plate systems and tricortical autograft require prolonged healing and develop nonunions more frequently. Complete consolidation was achieved using stand-alone cages filled with pure autogenous cancellous bone, but bony healing was delayed due to the cage. Rate of nonunions were: groups 1 and 4 0%, and groups 2 and 3 4.5% and 21%, respectively.

Thoracoscopic Debridement and Stabilization of Pyogenic Vertebral Osteomyelitis

The role of surgical debridement and internal fixation in treatment of vertebral osteomyelitis has been evolving. The standard surgical approach to thoracolumbar vertebral osteomyelitis requiring extensive thoracotomy or retroperitoneal exposure carries significant associated morbidity and postoperative pain. Minimally invasive thoracoscopic spine surgery is designed to improve postoperative morbidity associated with the traditional open surgery. We report a case of a 70-year-old man who developed T11-T12 pyogenic vertebral osteomyelitis 3 months after undergoing posterior laminectomy and microsurgical excision of a herniated thoracic disc. The patient underwent minimally invasive thoracoscopic radical debridement and anterior spinal reconstruction and fusion. Patients with vertebral osteomyelitis may benefit from the decreased postoperative morbidity that is associated with minimally invasive thoracoscopic spinal surgery.