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Osteoporosis is the most common metabolic bone disorder; through its prevalence and utilization of healthcare resources, the disease creates an enormous medical and economic burden that is set to worsen based on current population predictions. The transition of US healthcare from a volume-based to value-based reimbursement system presents an opportunity to address large population health problems such as osteoporosis. By reorganizing treatment plans and outcomes around the needs of the patient, the burden of osteoporosis can be managed in a more cost-effective way.

Central cord syndrome (CCS) represents a clinical phenomenon characterized by disproportionately greater motor impairment of the upper than of the lower extremities, bladder dysfunction. CSS is the most common form of incomplete traumatic spinal cord injury. The initial description of CSS was reported in 1887 secondary to cervical spinal trauma. However, recent literature describes a heterogenous injury patterns including high-energy and low-energy mechanisms and bimodal patient age distributions. Pathophysiology of clinical symptoms and neurological deficits often is affected by preexisting cervical spondylosis. Urgent clinical diagnosis is dependent on neurological examination and imaging studies. Treatment of CSS is dependent on injury mechanism and compressive lesions, neurological examination, preexisting cervical pathology, and patient-specific comorbidities. This article will review the current concepts in diagnosis, pathophysiology, and treatment of CSS with a highlighted case example.

Lumbar disc surgery is a common procedure in the USA. It is frequently performed with good or excellent results in most patients. This article reviews common causes of persistent radiculopathy after surgical intervention. We performed an extensive review of the literature as well as applying our own experience. Common causes of persistent leg pain following operative intervention include re-herniation, epidural fibrosis, biochemical/physiologic changes in the nerve root, and psychosocial issues. Patients with persistent leg pain after surgical treatment of lumbar disc herniation can pose a challenging clinical problem. Summary of these topics and available treatment options are reviewed.

The objective of this paper was to compare the reoperation rates, timing and causes between decompression alone and decompression plus fusion surgeries for degenerative lumbar diseases through a systematic review of the published data. A search of the literature was conducted on PubMed/MEDLINE, EMBASE and the Cochrane Collaboration Library. Reports that included reoperations after decompression alone and/or decompression plus fusion surgeries were selected using designed eligibility criteria. Comparative analysis of reoperation rates, timing and causes between the two surgeries was conducted. Thirty-two retrospective and three prospective studies were selected from 6401 papers of the literature search. The analysis of data reported in these studies revealed that both surgeries resulted in similar reoperation rates after the primary surgery. However, majority of reoperations following the fusion surgeries were due to adjacent-segment diseases, and following the decompression alone surgeries were due to the same-segment diseases. Reoperation rates were not found to decrease in patients operated more recently than those operated in early times. Reoperation rates were similar following decompression alone or plus fusion surgeries for degenerative lumbar diseases. However, different underlying major causes exist between the two surgeries. There is no evidence showing that the reoperation rate has a trend to decline with newer surgical techniques used. The exact mechanisms of reoperation after both surgeries are still unclear. Further researches are necessary to investigate the mechanisms of reoperation for improvement of surgical techniques that aim to delay or prevent reoperation after lumbar surgery. These slides can be retrieved under Electronic Supplementary Material.

Surgical intervention is often considered as the last option for patients suffering from significant spinal pain syndromes. In the absence of progressive neurological compromise or spinal deformity, most patients undergo an aggressive course of nonoperative treatment which tends to be very favorable in prognosis. Numerous nonoperative options are available; however, if these options have been exhausted and the patient continues to suffer from significant pain, disability, and/or neurological loss of function, then surgical options are discussed. Clinical outcomes are optimized by appropriateness of surgical intervention, proper identification of pain source, and patient preparation. Patients need to be medically and physically optimized and counseled at length regarding the risks and benefits of surgery as a form of shared decision-making. This chapter will focus on surgical intervention and options for decompression and stabilization in those patients suffering from pain syndrome.

rhBMP-2 is approved for use in single-level anterior lumbar interbody fusion (ALIF) within an LT-CAGE. Following impressive reports regarding the safety and efficacy of rhBMP-2 in ALIF, many surgeons have started using rhBMP-2 as a graft substitute for posterior lumbar fusion in an off-label manner. A number of studies have been published documenting the outcomes and complications seen following the off-label use of rhBMP-2 in the lumbar spine. In the setting of PLF, PLIF, and TLIF, fusion rates following the administration of rhBMP-2 are comparable, and at times, higher than the fusion rates seen with ICBG. rhBMP-2 is frequently associated with decreased blood loss and faster operative times as compared to ICBG. Radiculitis, osteolysis, and ectopic bone formation are adverse events seen related to the use of rhBMP-2 in PLIF and TLIF.

Study design Retrospective study. Objective To assess the relation between exposure to epidural steroid injection (ESI) before surgery and occurrence of surgical site infection (SSI) for degenerative lumbar spine conditions. Summary of background data The effect of local ESI on the occurrence of SSI is controversial. Methods Patients who underwent surgery for degenerative lumbar spine conditions at two centers between 2005 and 2015 were identified. Primary outcome measure was SSI within 90 days requiring surgical intervention. Results A total of 5311 patients (age 57 ± 16 years) were analyzed of which 945 (18%) had at least one ESI within 90 days of surgery. One hundred thirty-four (2.5%) patients developed an SSI requiring reoperation. No association of exposure or dose-response relationship was identified between ESI and SSI for any of the time periods (90-, 30-, and 30-90-day). Five (1.7%) of the 290 patients who had at least one ESI within 30 days before surgery had a postoperative infection compared to 129 (2.6%) of the 5021 in the non-ESI group (unadjusted odds ratio: 0.67, 95% CI: 0.27-1.64, P = 0.376). Fifteen (2.0%) of the 761 patients who had at least one ESI within 30 to 90 days before surgery had a postoperative infection, compared to 119 (2.6%) of the 4550 in the non-ESI group (unadjusted odds ratio: 0.75, 95% CI: 0.44-1.29, P = 0.296). Conclusion In this retrospective study we investigated whether an ESI and its timing influences the postoperative risk of an SSI. We found no association-exposure or dose-response relationship-between ESI and postoperative infection, even after adjusting for potential confounders, for any of the time periods (90-, 30-, and 30-90-day ESI). In addition, we did find that longer hospital stay, greater EBL, posterior approach, and drain placement were associated with higher infection rates. Level of evidence 3.

STUDY DESIGN Cross-sectional study reviewing 62 magnetic resonance imaging or computed tomography scans from consecutive adult patients with scoliotic spinal deformity in the thoracolumbar spine. OBJECTIVE To investigate the variation in anatomic position of retroperitoneal vessels in relationship to curve direction, location, magnitude, and axial rotation of curves in adult scoliosis. SUMMARY OF BACKGROUND DATA The minimally invasive lateral approach to the thoracolumbar spine avoids manipulation of abdominal and retroperitoneal structures and decreases risk of injury to paraspinal musculature. In adult patients with scoliosis, the varying anatomic relationship between retroperitoneal vessels and intervertebral disk spaces can increase the risk of vascular injury. MATERIALS AND METHODS Axial images were used to measure the anterior-posterior diameter of the inferior vertebral endplate with respect to the disk space perpendicular to the widest length of the disk. The overlap of the retroperitoneal vessels with the endplate were measured at the cephalad end vertebra, apex, and caudad end vertebra of each curve. Overlap and accessible disk space for individual disk spaces were also measured. RESULTS There was a significant difference in percentage overlap of the apex and cephalad vertebral endplate and inferior vena cava in right versus left-sided curves (P=0.002). Overlap between the inferior vertebral endplate and inferior vena cava at the cephalad, apex, and caudad end of the curve was significantly different between thoracolumbar and lumbar curves (P

The purpose of this article is to describe the different types of financial statements and the information they contain regarding the current and long-term financial health of a business practice. These statements are essential to guiding strategic decision making for physicians and executives.

Background context Surgical treatment for lumbar degenerative disc disease (DDD) has been associated with highly variable results in terms of postoperative pain relief and functional improvement. Many experts believe that DDD should be considered a chronic pain disorder as opposed to a degenerative disease. Genetic variation of the catechol- O -methyltransferase ( COMT ) gene has been associated with variation in human pain sensitivity and response to analgesics in previous studies. Purpose To determine whether genetic variation of COMT is associated with clinical outcome after surgical treatment for DDD. Study design Prospective genetic association study. Patient sample Sixty-nine patients undergoing surgical treatment for lumbar DDD. Diagnosis was based on documentation of chronic disabling low back pain (LBP) present for a minimum of 6 months and unresponsive to supervised nonoperative treatment, including activity modification, medication, physical therapy, and/or injection therapy. Plain radiographs and magnetic resonance imaging revealed intervertebral disc desiccation, tears, and/or collapse without focal herniation, nerve root compression, stenosis, spondylolisthesis, spondylolysis, or alternative diagnoses. Outcome measures Oswestry Disability Index (ODI) and visual analog score (VAS) for LBP. Methods Surgical treatment included 65 instrumented fusions and four disc arthroplasty procedures. All patients completed preoperative and 1-year postoperative ODI questionnaires. DNA was extracted from a sample of venous blood, and genotype analysis was performed for five common COMT single nucleotide polymorphisms (SNPs). Potential genetic association between these COMT SNPs and the primary outcome variable, 1-year change in ODI, was investigated using both single-marker and haplotype association analyses. Association with VAS scores for LBP was analyzed as a secondary outcome variable. Results Single-marker analysis revealed that the COMT SNP rs4633 was significantly associated with greater improvement in ODI score 1 year after surgery (p=.03), with individuals homozygous for the less common “T” allele demonstrating the largest improvement in ODI. Haplotype analysis of four COMT SNPs, rs6269, rs4633, rs4818, and rs4680, also identified a common haplotype “ATCA” (haplotype frequency of 39.3% in the study population) associated with greater improvement in ODI (p=.046). The greatest mean improvement in ODI was observed in patients homozygous for the “ATCA” COMT haplotype. A nonsignificant trend was observed between SNP rs4633 and greater improvement in VAS score for LBP. Conclusions This is the first study to report an association between surgical treatment success in DDD patients and genetic variation in the putative pain sensitivity gene COMT . These findings require replication in other DDD populations but suggest that genetic testing for pain-relevant genetic markers such as COMT may provide useful clinical information in terms of predicting outcome after surgery for patients diagnosed with DDD.

Study Design. Prospective observational study. Objective. To determine whether polymorphic variations of the guanosine triphosphate (GTP) cyclohydrolase 1 gene (GCH1) are associated with different outcomes in patients undergoing surgical treatment for lumbar degenerative disc disease (DDD). Summary of Background Data. GCH1, the gene encoding the rate-limiting enzyme in tetrahydrobiopterin synthesis, has been strongly implicated as a determinant of pain experience in previous animal and human studies. Methods. A total of 69 patients undergoing surgical treatment for lumbar DDD were prospectively enrolled. Genomic DNA was extracted from a venous blood sample, and DNA sequence analysis was performed of GCH1. Surgery included 65 instrumented fusions and 4 disc arthroplasty procedures. Patients were observed prospectively for 1 year following surgery. Allelic and genotype frequencies were calculated for each of 14 single nucleotide polymorphisms (SNPs). One-year postoperative Oswestry Disability Index (ODI) scores were compared to preoperative scores and the absolute change in ODI score was used to perform genetic association analyses on the basis of both individual SNP markers as well as commonly observed haplotypes for the entire gene sequence. Results. Single marker analysis revealed 1 SNP (rs998259; minor allele T) that was significantly associated with improvement in both absolute ODI score (P = 0.030) and Numerical Rating Scale back pain scores (P = 0.033) following surgery. Haplotype analysis identified a common GCH1 haplotype ("CACTTGTTTGAC") with a sample frequency of 12.3%, which was highly associated with improvement in absolute ODI score (P = 0.04). This haplotype frequency reflects the existence of both heterozygous and homozygous individuals in the study population. The presence of 1 unit of this haplotype was associated with an improvement in postoperative ODI score of 15.34 relative to the absence of this haplotype (P = 0.04). Conclusion. Preliminary results from this pilot genetic study of patients undergoing surgery for DDD suggests that the T allele at rs998259 of GCH1 may be associated with improved outcomes 1 year following surgery.

STUDY DESIGN/SETTING Retrospective review of a consecutive, nonrandomized series operated on by 2 surgeons. OBJECTIVE To evaluate the clinical and radiographic effectiveness of a silicated hydroxyapatite ceramic as a bone graft substitute in a series of patients undergoing posterolateral instrumented lumbar fusion. SUMMARY OF BACKGROUND DATA Newer-generation synthetic ceramics have been refined to maximize their host-graft interaction and stimulation of new tissue formation, including silicate-substitution. METHODS An independent radiologist interpreted the computed tomography images at 6, 12, and 24 months after surgery. Forty-two patients with 1- or 2-level lumbar degenerative disorders underwent posterior laminectomy (when indicated) and posterolateral fusion with instrumentation. Surgical levels included 15 patients who underwent 2-level and 27 single-level fusion procedures (57 levels operated on in total). RESULTS The average back pain scores improved from 5.6 ± 2.5 preoperative to 2.1 ± 2.5 at follow-up (P < 0.05). Similar results were seen with leg pain improvement from 5.8 ± 2.5 to 1.4 ± 1.9 (P < 0.05). At 6 months, 35% of levels revealed fusion, which increased to 76.2% and 76.5% at 12 and 24 months, respectively. No evidence of ectopic bone formation or osteolysis was noted. CONCLUSION In this study, a silicated calcium phosphate-based ceramic has been shown to be effective as a graft substitute and eliminate the need for autogenous iliac crest bone graft. The results confirm radiographic healing in posterolateral instrumented lumbar fusion at 24-months follow-up. The clinical outcomes also substantiate significant pain improvement consistent with published data in the literature compared with other bone graft alternatives.

Cross-sectional studies have demonstrated significant decreases in bone mass in femoral cortical bone adjacent to prostheses. Thirty-six patients who had undergone 31 cemented and 9 uncemented primary total hip arthroplasties (THA) were prospectively studied to define further the natural history of this femoral cortical bone loss. Dual-energy X-ray absorptiometry (DXA) was employed to quantify bone mineral density (BMD) changes in four subregions around the femoral prostheses. Femoral BMD loss (average 12.3%) was observed in the three proximal subregions 2 months postoperatively. This loss increased to 21.2% by 6 months postoperatively, and by 2 years postoperatively it averaged 25.5% in the same three subregions. There were no significant BMD changes in the subregion distal to the prosthesis tip or in the contralateral hip. Subgroups were compared based on prosthesis size and cement use. Statistically significant differences in BMD loss were observed between the large cemented cobalt chrome prosthesis group (n = 8) and the large uncemented titanium prosthesis group (n = 8). These differences were only present in the most proximal medial subregion where the large cemented groups had twice the bone loss in this area as compared with the large uncemented group. The data indicate that bone loss occurs adjacent to femoral prosthesis within 2 months of surgery and that DXA is a useful technique to quantify prospectively femoral cortical bone loss following THA.

Background context Morbidity associated with autologous bone graft harvest is an important factor in determining the utility of expensive alternatives such as recombinant bone morphogenic protein. The most frequently reported complication associated with graft harvest is chronic pain. Purpose To prospectively determine the degree of pain and morbidity associated with autologous iliac crest bone graft harvest and its effect on activities of daily living. Study design Prospective observational cohort study. Patient sample One hundred ten adult patients undergoing elective posterior lumbar spinal fusion surgery involving autologous iliac crest bone graft harvest. Outcome measures Patient self-reported Visual Analog Scale (VAS) scores for pain and a study-specific questionnaire regarding activities of daily living. Methods One hundred ten patients were prospectively enrolled. Postoperative VAS scores (0–100) for harvest site pain were obtained at 6-week, 6- and 12-month follow-up. Patients completed a 12-month questionnaire regarding the persistence of specific symptoms and resulting limitation of specific activities. Results One hundred four patients were available for 1-year follow-up. Mean VAS pain scores (scale 0–100) at 6 weeks, 6 and 12 months were 22.7 (standard deviation [SD], 25.9), 15.9 (SD, 21.5), and 16.1 (SD, 24.6), respectively. At 12 months, 16.5% reported more severe pain from the harvest site than the primary surgical site, 29.1% reported numbness, and 11.3% found the degree of numbness bothersome, whereas 3.9% were bothered by scar appearance. With respect to activity limitations resulting from harvest site pain at 1 year, 15.1% reported some difficulty walking, 5.2% with employment, 12.9% with recreation, 14.1% with household chores, 7.6% with sexual activity, and 5.9% irritation from clothing. Conclusions There is a significant rate of persistent pain and morbidity from iliac crest bone graft harvest when associated with elective spine surgery. Mean pain scores progressively decline over the first postoperative year. Nevertheless, harvest site pain remains functionally limiting in a significant percentage of patients 1 year after surgery. Rates of functional limitation are higher than previously reported and may be because of increased sensitivity of the prospective study design and targeted investigation of these specific symptoms. Validity of these findings is necessarily limited by patient ability to discriminate harvest site pain from alternative sources of back and buttock pain.

Background context The CHARITE artificial disc, a lumbar spinal arthroplasty device, was approved by the United States Food and Drug Administration in 2004 based on two-year safety and effectiveness data from a multicenter, prospective, randomized investigational device exemption (IDE) study. No long-term, randomized, prospective study on the CHARITE disc or any other artificial disc has been published to date. Purpose The purpose of this study was to compare the safety and effectiveness at the five-year follow-up time point of lumbar total disc replacement using the CHARITE artificial disc (DePuy Spine, Raynham, MA) with that of anterior lumbar interbody fusion (ALIF) with BAK cages and iliac crest autograft, for the treatment of single-level degenerative disc disease from L4 to S1, unresponsive to nonoperative treatment. Study design/setting Randomized controlled trial—five-year follow-up. Patient sample Ninety CHARITE patients and 43 BAK patients. Outcome measures Self-reported measures: visual analog scale (VAS); validated Oswestry disability index (ODI version 1.0); Short-Form 36 Questionnaire, and patient satisfaction. Physiologic measures: radiographic range of motion, disc height, and segmental translation. Functional measures: work status. Methods Of the 375 subjects enrolled in the CHARITE IDE trial, 277 were eligible for the five-year study and 160 patients thereof completed the five-year follow-up. The completers included 133 randomized patients. Overall success was defined as improvement≥15pts in ODI vs. baseline, no device failure, absence of major complications, and maintenance or improvement of neurological status. Additional clinical outcomes included an ODI questionnaire as well as VAS, SF-36, and patient satisfaction surveys. Work status was tracked for all patients. Safety assessments included occurrence and severity of adverse events and device failures. Radiographic analyses such as index- and adjacent-level range of motion, segmental translation, disc height, and longitudinal ossification were also carried out. Results Overall success was 57.8% in the CHARITE group vs. 51.2% in the BAK group (Blackwelder's test: p=0.0359, Δ=0.10). In addition, mean changes from baseline for ODI (CHARITE: −24.0pts vs. BAK: −27.5pts), VAS pain scores (CHARITE: −38.7 vs. BAK: −40.0), and SF-36 questionnaires (SF-36 Physical Component Scores [PCS]: CHARITE: 12.6pts vs. BAK: 12.3pts) were similar across groups. In patient satisfaction surveys, 78% of CHARITE patients were satisfied vs. 72% of BAK patients. A total of 65.6% patients in the CHARITE group vs. 46.5% patients in the BAK group were employed full-time. This difference was statistically significant (p=0.0403). Long-term disability was recorded for 8.0% of CHARITE patients and 20.9% of BAK patients, a difference that was also statistically significant (p=0.0441). Additional index-level surgery was performed in 7.7% of CHARITE patients and 16.3% of BAK patients. Radiographic findings included operative and adjacent-level range of motion (ROM), intervertebral disc height and segmental translation. At the five-year follow-up, the mean ROM at the index level was 6.0° for CHARITE patients and 1.0° for BAK patients. Changes in disc height were also similar for both CHARITE and BAK patients (0.7mm for both groups, p=0.9827). Segmental translation was 0.4 and 0.8mm in patients implanted with CHARITE at L4–L5 vs. L5–S1, respectively, and 0.1mm in BAK patients. Conclusions The results of this five-year, prospective, randomized multicenter study are consistent with the two-year reports of noninferiority of CHARITE artificial disc vs. ALIF with BAK and iliac crest autograft. No statistical differences were found in clinical outcomes between groups. In addition, CHARITE patients reached a statistically greater rate of part- and full-time employment and a statistically lower rate of long-term disability, compared with BAK patients. Radiographically, the ROMs at index- and adjacent levels were not statistically different from those observed at two-years postsurgery.

Object New generations of devices for spinal interbody fusion are expected to arise from the combined use of bioactive peptides and porous implants. The purpose of this dose-ranging study was to evaluate the fusion characteristics of porous ceramic granules (CGs) coated with the bioactive peptide B2A2-K-NS (B2A) by using a model of instrumented lumbar interbody spinal fusion in sheep. Methods Instrumented spinal arthrodesis was performed in 40 operative sites in 20 adult sheep. In each animal, posterior instrumentation (pedicle screw and rod) and a polyetheretherketone cage were placed in 2 single-level procedures (L2–3 and L4–5). All cages were packed with graft material prior to implantation. The graft materials were prepared by mixing (1:1 vol/vol) CGs with or without a B2A coating and morselized autograft. Ceramic granules were coated with B2A at 50, 100, 300, and 600 μg/ml granules (50-B2A/CG, 100-B2A/CG, 300-B2A/CG, and 600-B2A/CG, respectively), resulting in 4 B2A-coated groups plus a control group (uncoated CGs). Graft material from each of these groups was implanted in 8 operative sites. Four months after arthrodesis, interbody fusion status was assessed with CT, and the interbody site was further evaluated with quantitative histomorphometry. Results All B2A/CG groups had higher CT-confirmed interbody fusion rates compared with those in controls (CGs only). Seven of 8 sites were fused in the 50-B2A/CG, 100-B2A/CG, and 300-B2A/CG groups, whereas 5 of 8 sites were fused in the group that had received uncoated CGs. New woven and lamellar bone spanned the fusion sites with excellent osseointegration. There was no heterotopic ossification or other untoward events attributed to the use of B2A/CG in any group. Each B2A/CG treatment produced more new bone than that in the CG group. Conclusions Bioactive treatment with B2A effectively enhanced the fusion capacity of porous CGs. These findings suggest that B2A/CG may well represent a new generation of biomaterials for lumbar interbody fusion and indicate that additional studies are warranted.

Background Although halo-vest immobilization remains a common form of treatment for type II odontoid fractures, nonunion and C1–2 instability may be the result in up to 20% to 40% of patients. Purpose Supine and upright lateral X-ray films may allow early identification of patients likely to fail halo-vest treatment and earlier surgical treatment with decreased morbidity from prolonged unsuccessful halo-vest immobilization. Study design/setting A prospective cohort study was performed. Patient sample Twenty patients with type II odontoid fractures. Outcome measures Posttreatment nonunion and C1–2 instability as determined by plain X-ray films and computed tomography scan. Methods Both supine and upright lateral X-ray films were obtained immediately after halo-vest application and at the 2-week, 6-week, and 3-month follow-up. Flexion-extension lateral X-ray films were obtained after halo-vest removal. Patients with nonunion or instability underwent computed tomography scan. Upright X-ray films were compared serially to identify loss of reduction. Pairs of supine and upright X-ray films were compared to measure any change in displacement or angulation upon transition from supine to upright position. Nonunion patients were compared with healed patients to determine any difference in fracture behavior based on serial supine and upright X-ray films. Results Twenty patients with type II odontoid fractures were identified during the study period. Three patients with multiple trauma underwent immediate surgical stabilization. Three elderly patients with nondisplaced fractures were treated in a cervical orthosis. Fourteen patients initiated and completed 3 months of halo-vest immobilization. After halo-vest removal, 4 of 14 patients (29%) showed radiographic nonunion or instability. In all 4 nonunion patients, supine and upright radiographs at 2 weeks revealed change in fracture angulation ≥5° between the supine and upright positions. In three of these patients standard serial upright lateral X-ray films failed to identify any loss of reduction. In the remaining patient, progressive angulation of 15° was observed. No measurable change in angulation between supine and upright X-ray films was observed in any patient who healed successfully with halo-vest treatment. Conclusions Obtaining both supine and upright lateral X-ray films during the follow-up period may identify patients at risk for failure of halo-vest treatment as early as 2 weeks after initiation of treatment. A change in fracture angulation ≥5° suggests an increased risk of treatment failure and the potential benefit of early surgical stabilization.

Background context Conditions requiring posterior lumbar spinal fusion remain a clinical challenge. Achieving arthrodesis using autogenous bone graft is inconsistent when rigid internal fixation such as transpedicular instrumentation is applied. Synthetic materials, particularly calcium phosphate–based ceramics, have shown promise for spine fusion applications, especially when combined with autograft. Silicate substitution has been shown to enhance the bioactivity of calcium phosphates and may obviate the need for autologous supplementation. Purpose Determine efficacy of silicated calcium phosphate (Si-CaP) compared with autograft to generate solid lumbar fusion. Study design Comparison of healing of instrumented posterolateral lumbar fusion in ewes at 2 and 6 months using Si-CaP or iliac crest autograft. Methods Eighteen skeletally mature ewes underwent implantation of either autograft or Si-CaP in the space spanning the L4–L5 transverse process. In vivo quantitative computed tomography (CT) scans were made at 2-month intervals and after euthanasia. Harvested spine segments were radiographed and biomechanically tested in bending at 6 months. Histological assessments were made at 2 and 6 months. Results Animals receiving Si-CaP graft were biomechanically and radiographically equivalent to those receiving autograft. Fusion mass density and volume were higher for the Si-CaP group throughout the healing period. Si-CaP regenerated normal bone tissue morphology, cellularity, and maturation with no inflammatory responses despite the fact that no autograft, bone marrow aspirate, or blood was mixed with the material. Histomorphometrically, fusion mass was higher for Si-CaP and bony bridging was equivalent when compared with autograft treatment. Conclusions Si-CaP was biomechanically, radiographically, and histologically equivalent to autograft in generating a solid, bony, intertransverse process fusion in an ovine model. Both treatment groups achieved 100% bridging fusion after 6 months of healing.

STUDY DESIGN Retrospective study. OBJECTIVES To determine the frequency of pedicle screw violation of superior nonfused facet joints adjacent to the most cephalad pedicle screws after a midline approach for lumbar fusion. SUMMARY OF BACKGROUND DATA Facet-joint violations have been evaluated in patients undergoing lumbar pedicle screw instrumentation and fusion with a Wiltse muscle-splitting approach, but not via the more common midline approach. METHODS Between 1995 and 2003, 204 patients underwent this procedure. Computed tomography scans (within 1 year postsurgery) were evaluated independently for superior facet-joint violation. chi tests were used to examine bivariate associations of superior level facet-joint violation, patient age, construct level, diagnosis, and revision status for significance (P < or = 0.05). RESULTS Superior-level facet-joint violation occurred in 24% of patients and 15% of screws, twice as often on the left side (P = 0.0396) than on the right, more frequently in single than in multiple-level procedures (P < 0.0001), and most frequently with the most cephalad screws at L5 (48%). We found no significant associations between violation rates and other designated parameters. CONCLUSION The left side, single-level fusion, and most cephalad pedicle screws at L5 are targets for interventions to reduce pedicle violations in this procedure.

The current debate over the efficacy of lumbar fusion for low back pain has not been settled. Fritzell et al published a landmark paper entitled "Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish lumbar spine study group." Their goal was to provide objective evidence supporting lumbar fusion. While it was well designed and important to our knowledge base, it has limitations. We set out to review their work in an unbiased yet critical manner. Our goals are to summarize the strengths and weaknesses of the paper, place it in the context of current knowledge, and highlight its significance for present-day practice and research. From technical and study design perspectives, Fritzell et al were able to validate the use of lumbar fusion for the treatment of low back pain. However, their use of "usual nonoperative" care and nonspecific definition of low back pain precluded a truly genuine comparison of operative and nonoperative groups. We commend the Swedish lumbar spine study group and their remarkable efforts; they elevated the sophistication of spine research and spawned many more excellent works to help settle the ongoing controversy on the ideal treatment of low back pain.

Background context The rise in spinal fusion procedures has led to an increase in the available number and variety of bone graft substitutes. As our understanding of the biologic processes that influence bony fusion has improved, appreciation for the role of the carrier material involved in bone grafts has also increased. Purpose The abundance of products available leaves a surgeon with many choices. Knowledge of the current advances will allow for more critical review of the literature and improved decision making when choosing bone graft materials. Study design/setting Review of the English-language literature. Methods A critical review of basic science, animal and human studies that investigate the types and role of carrier materials used in spine surgery. Results The myriad of carrier material available to the spine surgeon is related to the many options in bone graft material. Allograft is an important osteoconductive agent but has its disadvantages especially in regard to disease transmission and immunogenicity. Collagen in various forms is an effective carrier for bone morphogenic protein and autogenous stem cells and can be easily combined with other bone graft materials. Synthetic options include hydroxyapatite and calcium phosphate ceramic materials with different formulations; all are osteoconductive only but can be combined with osteoinductive and/or osteogenic components. Bioabsorbable carriers are effective for use with bone morphogenic protein and can also be used in multiple forms and settings. Conclusions Many bone graft carriers exist, and multiple studies have shown their efficacy. It appears that no one carrier is ideal but each situation might influence the choice of one carrier over another.

Anterior cervical discectomy and fusion (ACDF) is a successful procedure for the degenerative cervical spine. One goal of the fusion is to restore the loss of disc height that results from the degenerative process. Whereas cervical alignment improves with increased disc height, the ideal graft size used for disc space restoration is unknown. Few studies have examined the relationships between these changes in cervical alignment and clinical outcomes.All patients underwent a single-level ACDF at the authors' institution. Radiographs at early and final follow-up were examined, and three measurements were made: disc height, disc space angulation, and spinous process distance. These radiographic measurements were correlated with Visual Analog Scales (VASs) for neck and arm pain and Oswestry Disability Index (ODI).There were significant changes in disc height (5.3 vs 7.0 mm) as well as disc space angulation (3.3 degrees vs 0.1 degrees ). Reduction in neck pain VAS score (6.7 vs 3.2) and arm pain VAS score (5.1 vs 2.3) was significant. ODI scores were not statistically different, but improvement of 20.1% was observed. Correlations between radiographic parameters and clinical outcomes were moderate to low, and none was significant.While restoration of cervical alignment and disc height is important, clinical results are critical in analysis of outcomes following ACDF. We have shown that although clinical outcomes remain good, there does not appear to be any strong correlation with radiographic results. Emphasis on restoration of cervical alignment appears justified, but its influence on clinical outcomes may be overstated.

Background context Rheumatoid arthritis is a debilitating polyarthropathic degenerative condition. Eighty-six percent of patients with rheumatoid arthritis have cervical spine involvement. Often these lesions are clinically asymptomatic or symptoms are erroneously attributed to peripheral manifestation of the patient's rheumatoid disease. Because these lesions are common and missed diagnosis can result in death, early recognition is vital. Purpose The purpose of this literature review is to identify common lesions present in the rheumatoid neck and review diagnostic methods as well as treatment options for those requiring surgical intervention. Study design A review of the English medical literature with focus on more recent studies on the presentation, diagnosis, management, surgical treatment and clinical outcomes of rheumatoid arthritis of the cervical spine. Methods A comprehensive literature review of the English medical literature obtained through Medline up to November 2003 was performed identifying relevant and more recent articles that addressed the presentation, evaluation, surgical management and outcomes of rheumatoid patients with cervical spine involvement. Results If left untreated, a large percentage of rheumatoid patients with cervical spine involvement progress toward complex instability patterns resulting in significant morbidity and mortality. Once myelopathy occurs, prognosis for neurologic recovery and long-term survival is poor. In properly selected patients, anterior and/or posterior cervical procedures can prevent neurologic injuries and preserve remaining function. Conclusion Cervical spine involvement in the rheumatoid patient is common and progressive. Early diagnosis and treatment is imperative; however, surgical intervention should be considered carefully because associated morbidity and mortality is high.

The low lumbar burst fracture occurs in a unique anatomic zone with distinct biomechanical features as compared to the more common thoracic and upper lumbar fracture. Several relative surgical indications for a low lumbar burst fracture exist and include the presence of neurologic deficit including acute radiculopathy with associated weakness or cauda equina syndrome, severe lumbosacral kyphotic deformity, or progression of deformity despite nonoperative treatment. The surgical management of the low lumbar burst fracture must be individualized based upon fracture anatomy, neurologic status of the patient, and sagittal plane alignment. Surgery offers the patient with neurologic compromise the best option for restoration of normal function.

Anterior cervical discectomy and fusion with autograft is a safe and effective procedure for the treatment of cervical radiculopathy and myelopathy and has been extensively studied in the literature. Controversies arise as to the optimal graft material for insertion into the disc space as well as the use of, and indications for, anterior plating. Recently, cervical interbody cages have added to this controversy. Many cervical cage designs exist; however, the most common is the threaded titanium interbody device. Proponents of the cervical cage believe that the cage can achieve the same fusion rate as anterior cervical discectomy and fusion with minimal complications. Furthermore, cervical cage use can circumvent the morbidity associated with autograft harvest and the risk of infection associated with allograft. The literature from the last 2 years has focused mainly on in vivo fusion rates and in vitro biomechanical flexibility and stability analysis.

Background context: The use of rigid instrumentation combined with bone graft makes intuitive sense given the requirements for vascular ingrowth, bone formation and a stable environment for the cellular events of healing to develop. However, with the advances of potent osteoinductive growth factors, the role of internal fixation may come into question. Whether bone morphogenic proteins (BMPs) would benefit from a more "stable" spinal segment for bone production and modeling remains unknown. In addition, it is unknown whether BMP and rigid fixation may have an additive effect on fusion healing. Purpose: This study is proposed to test the hypothesis that rigid fixation in the lumbar spine would be advantageous to achieve fusion for autogenous bone grafting, but fusion would occur regardless of fixation with the use of osteogenic protein (OP)-1. Study design/setting: A histologic and radiographic analysis of BMP in a rabbit lumbar fusion model. Methods: Thirty-two rabbits were randomized into four groups: 1) control animals: in situ posterolateral L5–L6 arthrodesis using autogenous iliac crest bone graft; 2) fixation group: posterolateral arthrodesis L5–L6 with autogenous bone graft and interspinous fixation; 3) OP-1 group: in situ posterolateral L5–L6 arthrodesis using OP-1 and 4) combined OP-1 and fixation group. Radiographic fusion analysis was performed with computed tomography scans at 3 and 12 weeks after surgery. Decalcified histology was performed to assess tissue morphology and cellularity. Results: Minimal evidence of fusion was noted at 3 weeks with autograft or OP-1. By 12 weeks, all OP-1–treated animals had solid fusion, whereas no fusion was noted in autograft animals. The addition of fixation slightly increased radiographic fusion at 3 weeks in autograft and OP-1 groups but did not affect OP-1 animals at 12 weeks where all were fused. Decalcified histologic results confirmed the proliferative bone formation noted with OP-1 and the variable cellular response with autograft. Conclusions: The results of the present study suggest that the osteoinductive effect of OP-1 may be only minimally enhanced early in the bone healing process but does not appear to be affected in the long term by spinal fixation in the rabbit intertransverse fusion model. Fixation appeared to enhance early fusion in the autograft group.

The authors performed a prospective study of 63 patients with cervical radiculopathy treated with Robinson anterior cervical discectomy and fusion and compared the traditional or standard and reverse graft techniques. Modifications of the standard Robinson grafting techniques have been proposed. The reverse graft technique has theoretical advantages, including limiting the deleterious effects of graft extrusion and maintaining rigid middle column support. A radiographic evaluation and an assessment of clinical outcome based on the criteria of Odom were performed prospectively for as long as 1 year after surgery. Thirty-one patients were treated with the standard grafting technique and 32 with the reverse graft orientation. The radiographic evaluation showed no significant differences between the two techniques with regard to sagittal alignment and disk heights. The overall fusion grade was higher in the reverse graft technique (p < 0.05). There were 93% and 96% good to excellent results in the standard graft and reverse graft groups, respectively. The authors report no significant differences associated with the standard or reverse anterior cervical grafting techniques in terms of radiographic alignment or disk height loss over time or at early clinical outcome. However, improved fusion grade was noted with the reverse graft technique, which may be related to end plate and intervertebral space preparation. The reverse grafting technique is an acceptable alternative to the standard graft orientation.

Neck pain can originate from any number of factors. Perhaps the most difficult symptom complex to resolve is axial neck pain arising from upper cervical nerve root compression. The purpose of this study is to report the results of surgical intervention in a series of patients with neck pain from C4 radiculopathy. Twelve consecutive patients who were diagnosed with C4 radiculopathy were retrospectively reviewed (follow-up, 22+/-16.3 months). Patients underwent either anterior cervical discectomy and fusion or posterior laminoforaminotomy at the C3-C4 segment. The results show that a good to excellent clinical result can be achieved in most patients (92% in our series). The importance of identifying patients with C4 radiculopathy lies in the fact that surgery can alter the natural history of neck pain secondary to upper cervical root radiculopathy, unlike axial neck pain from degenerative disk disease.

Background: C5 nerve palsy is a known complication of cervical spine surgery. The development and etiology of this complication are not completely understood. The purpose of the present study was to determine whether rotation of the cervical spinal cord predicts the development of a C5 palsy. Methods: We performed a retrospective review of prospectively collected spine registry data as well as magnetic resonance images. We reviewed the records for 176 patients with degenerative disorders of the cervical spine who underwent anterior cervical decompression or corpectomy within the C4 to C6 levels. Our measurements included area for the spinal cord, space available for the cord, and rotation of the cord with respect to the vertebral body. Results: There was a 6.8% prevalence of postoperative C5 nerve palsy as defined by deltoid motor strength of ≤3 of 5. The average rotation of the spinal cord (and standard deviation) was 2.8° ± 3.0°. A significant association was detected between the degree of rotation (0° to 5° versus 6° to 10° versus ≥11°) and palsy (point-biserial correlation = 0.94; p < 0.001). A diagnostic criterion of 6° of rotation could identify patients who had a C5 palsy (sensitivity = 1.00 [95% confidence interval, 0.70 to 1.00], specificity = 0.97 [95% confidence interval, 0.93 to 0.99], positive predictive value = 0.71 [95% confidence interval, 0.44 to 0.89], negative predictive value = 1.00 [95% confidence interval, 0.97 to 1.00]). Conclusions: Our evidence suggests that spinal cord rotation is a strong and significant predictor of C5 palsy postoperatively. Patients can be classified into three types, with Type 1 representing mild rotation (0° to 5°), Type 2 representing moderate rotation (6° to 10°), and Type 3 representing severe rotation (≥11°). The rate of C5 palsy was zero of 159 in the Type-1 group, eight of thirteen in the Type-2 group, and four of four in the Type-3 group. This information may be valuable for surgeons and patients considering anterior surgery in the C4 to C6 levels. Level of Evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

We have previously shown that calcitonin (CT), an inhibitor of bone resorption, increases vertebral, but not femoral bone density in the rat [3]. To address the physiologic responses associated with these effects on bone mineral density (BMD), we assessed mRNA transcripts reflecting activities of osteoblasts (type I collagen, osteocalcin, osteopontin, and alkaline phosphatase), osteoclasts [tartrate-resistant acid phosphatase (TRAP)], and cell proliferation (histone H4) in the spine and femur of these rats. CT increased spine BMD while increasing type I collagen and decreasing TRAP and histone mRNAs. In the femur, where CT had no effect on BMD, it decreased type I collagen and histone H4 mRNA but did not affect TRAP. CT had no effect on the gene expression of osteocalcin, osteopontin, or alkaline phosphatase at either site. The results indicate that selective alterations in gene expression, as reflected by steady state mRNA levels, are consistent with the changes observed by BMD measurement, and can more clearly define the specific contribution from osteoblast and osteoclast activity. This study demonstrates a heterogeneity in response of the axial and appendicular skeleton to CT, reflected by alterations in gene expression that provide a basis for understanding the observed BMD responses to various pharmacologic interventions.

Thoracic pain that originates from thoracic spine pathology is uncommon, and it is reported to represent not more than 5% of all common spinal pain symptoms [1]. Presentations of thoracic spinal pain include “band-like” chest pain, focal pain in the mid back, and pain on deep breathing [1]. Given the paucity of primary thoracic spine pathologies, persistent thoracic pain should prompt consideration of serious conditions such as spinal infection; malignant neoplasm; traumatic or nontraumatic vertebral compression fractures; and extraspinal pathologies, such as rib fractures, peptic ulcer disease, pancreatitis, cholecystitis, pleuritis, and aortic aneurysms [1]. The incidence of infectious spondylodiskitis in developed countries is 4-24 per million each year [2]. Spondylodiskitis in adults is considered very rare; it usually follows surgical interventions or presents in cases of generalized septicemia [3]. In this report, we present a patient who described a new onset of thoracic pain that progressed without improvement, the evaluation that led to the diagnosis of coccidioidomycosis diskitis and vertebral osteomyelitis, and the course of treatment. We also discuss the diagnostic and therapeutic options and previous reports of this pathology.

TSH-suppressive doses of thyroid hormone are associated with bone loss. We have previously reported that L-T4 decreases femoral, but not vertebral bone mineral density (BMD) in rats. As bisphosphonates are able to decrease bone resorption, especially in high bone turnover states, we investigated the potential effects of etidronate disodium (EHDP) on L-T4-induced bone loss in the rat model by assessing BMD and gene expression of osteoblast (osteocalcin, osteopontin, type I collagen, and alkaline phosphatase), osteoclast (tartrate-resistant acid phosphatase), and cell growth (histone) markers in the skeleton. L-T4 administered for 20 days decreased BMD in the femur, but had no effect on the lumbar spine. EHDP alone had no effect on femoral or vertebral BMD, but did prevent the L-T4-induced bone loss in the femur. L-T4 increased mRNA levels of alkaline phosphatase, tartrate-resistant acid phosphatase, and histone H4 in the femur, but not in the vertebrae. EHDP, which alone had no effect on gene expression in the femur or vertebrae, inhibited the effect of L-T4 on mRNA markers in the femur. The results demonstrate that EHDP can prevent the L-T4-induced decrease in femoral BMD in rats that is associated with the prevention of changes in mRNA markers of osteoclast and osteoblast function. EHDP and other bisphosphonate compounds may be useful in the prevention of thyroid hormone-induced bone loss in humans.

1 alpha,25-Dihydroxyvitamin D3 exerts rapid nongenomic effects on rat osteoblast-like cells independent of the classic nuclear receptor. These effects include changes in phospholipid metabolism and cell calcium. Intracellular calcium itself has been proposed to regulate intracellular pH in osteoblast cell lines. The purpose of this study was to determine the effect of 1 alpha,25-dihydroxyvitamin D3 on intracellular pH, the relationship of changes in calcium to changes in pH, and the role of pH changes in genomic activation. 1 alpha,25-Dihydroxyvitamin D3 increased intracellular pH within 10 min in rat osteoblast-like cells, an effect that was inhibited by removal of extracellular sodium and by the biologically inactive epimer 1 beta,25-dihydroxyvitamin D3. The hormone increased intracellular calcium in Quin 2 loaded cells in the presence and absence of extracellular sodium. The 1 alpha,25-dihydroxyvitamin D3-induced increments in osteocalcin and osteopontin mRNA levels were abolished in sodium-free medium. The results indicate that 1 alpha,25-dihydroxyvitamin D3-induced increments in cellular calcium precede cell alkalinization and that these changes in intracellular pH may modulate steady-state mRNA levels of genes induced by vitamin D.

Gallium nitrate (GN) is an inhibitor of bone resorption and thereby may result in a change in coupled bone formation. In the present investigation the effects of GN on bone formation were studied in the rat osteosarcoma (ROS) 17/2.8 cell line and normal diploid rat osteoblasts (ROB) in vitro and the femur of rats treated in vivo, measuring mRNA levels for two osteoblast parameters, type I collagen, a marker of matrix formation, and osteocalcin, a bone specific protein and also histone H4, a marker of cell proliferation. GN, at 50 microM for 3 h, increased type I collagen mRNA levels by 132% in ROS 17/2.8 cells and by 122% in proliferating ROB cells. Osteocalcin (OC) mRNA levels were decreased by 61% in ROS 17/2.8 cells and by 97% in differentiated ROB cells. These changes occurred in the absence of any effects on cell proliferation. Seventy-day-old female rats were then treated with GN, 0.5 mg/kg/day, for 3 weeks. As previously reported, GN decreased serum calcium levels, but had no effect on lumbar or femoral bone density. In contrast to the in vitro effects, GN had no effect on type I collagen steady-state mRNA levels in the femur; however, it decreased OC steady-state mRNA levels in the femur by 58%. These results suggest that GN has similar in vitro effects in transformed and normal osteoblasts, while the collagen-stimulatory effects observed in vitro cannot be extrapolated to in vivo models. The consistent inhibition of osteocalcin in vitro and in vivo suggests a more specific target for GN that may relate to its effects in inhibiting bone resorption in normal rats.

Study design Retrospective consecutive series review. Objective To examine performance of transcranial motor-evoked potential (TcMEP) monitoring in patients undergoing surgery for cervical myelopathy and potential risk factors for false positive alerts. Summary of background data Although use of TcMEP monitoring has been increasing and has been specifically recommended in patients with cervical myelopathy, rates and risk factors for false positive alerts have not been established. Methods Intraoperative neuromonitoring data for 52 consecutive patients undergoing surgery for cervical myelopathy were reviewed. All major TcMEP alerts were identified. Comprehensive demographic and clinical data, preoperative imaging studies, operative, and anesthesia records were reviewed. Results Six of 52 patients (12%) experienced a major TcMEP alert consisting of sustained >80% loss of amplitude. There were no somatosensory-evoked potential (SSEP)-related alerts. In 2 cases, an intraoperative wake-up test was negative and in 3 cases, surgery was completed without a wake-up test and without recovery of TcMEP signals. No new postoperative neurologic deficits were observed in these patients. One patient with new postoperative weakness was correctly predicted by loss of TcMEP signals. No new deficit was observed in the remaining 46 patients. Statistical analysis revealed significantly higher body mass index (28.8 vs. 35.0; P = 0.032) and length of surgery (191 vs. 283 minutes; P = 0.019) in patients with false positive alerts. Conclusion In this series of cervical myelopathy patients, sensitivity and specificity of TcMEP for detection of clinically significant intraoperative cord injury were 100% and 90%, respectively. Sensitivity and specificity of SSEP were 0% and 100%, respectively. The positive predictive value of a TcMEP alert was 17%. Possible risk factors for false positive TcMEP alerts include obesity and increased length of surgery. This study supports superior sensitivity of TcMEP compared with SSEP monitoring but identifies a relatively high false positive rate even in a selected high-risk cervical myelopathy population when this modality is applied in practice.

This study addressed radiographically the evaluation, presence, location, and degree of subsidence with secondary focus on the various clinical parameters and outcomes in 32 patients who underwent anterior cervical discectomy and fusion (ACDF) with tricortical iliac crest bone grafts and rigid anterior plate fixation. Postoperative follow-up plain radiographs were evaluated to determine subsidence on lateral neutral images by measuring the change in height of interscrew distance (ISD) and anterior (AVD), mid (MVD), and posterior (PVD) vertebral endplate-to-endplate vertical distances. Clinical functional outcome and various risk factors were also addressed. A 100% fusion rate was achieved, no instrumentation-related complications were noted, and mild graft subsidence occurred in each patient after the initial 2 months of surgery. Mean AVD, MVD, and PVD were 1.2 mm, 0.4 mm and 0.6 mm, respectively. Mean ISD was 0.6 mm. Percent change for AVD, MVD, PVD, and ISD was 2.3%, 0.8%, 1.2%, and 1.2%, respectively. Subsidence was more pronounced at the anterior vertebral graft-endplate interface (P.05). Satisfactory clinical results were reported in 90.9% of the patients. With such a sample size, age, sex, smoking status, plate design, graft type, and operative or number of fused levels did not demonstrate statistically significant differences to the degree of subsidence. This paper has shown that ACDF with tricortical bone grafts and rigid plating is associated with slight subsidence, graft load-sharing, high fusion rate, and excellent clinical outcome.

Study design Consecutive case series of patients with C6 and C7 radiculopathies. Objectives To explore the clinical utility and reliability of manual muscle testing of forearm pronation strength in C6 and C7 radiculopathies. Summary of background data EMG evidence of denervation of the pronator teres was the most common finding in C6 radiculopathies, and frequently present in C7 radiculopathies. Clinical evaluation of the pronator teres through manual muscle testing of forearm pronation has never been explored; therefore, its clinical utility is unknown as compared with the muscle groups that are traditionally evaluated. Methods Fifty-five subjects with diagnostic imaging evidence of either C6 (n = 25) or C7 (n = 30) cervical root compression and clinical symptoms consistent with cervical radiculopathy were recruited for this study. These subjects underwent manual muscle testing of forearm pronation, wrist extension, elbow flexion, and elbow extension. The frequency of impaired strength was recorded and compared for C6 and C7 radiculopathies. A second examiner evaluated each subject, with his or her findings compared with the first examiner only for the determination of interrater reliability. Results In C6 radiculopathy subjects, forearm pronation weakness was present in 72%, was twice as common as wrist extension weakness, was present in all cases where elbow flexion or wrist extension weakness was noted, and was found in all but 2 subjects where elbow extension weakness was present. In C7 radiculopathy subjects, forearm pronation weakness accompanies elbow extension weakness in 23% of subjects and was the only weakness in 10% of subjects. Manual muscle testing demonstrated adequate interrater reliability. Conclusions Forearm pronation weakness is the most frequent motor finding in C6 radiculopathies and may be noted is some cases of C7 nerve root compression.

Background context Anterior cervical plates are commonly used to provide immediate stabilization after a variety of cervical spine procedures. It has been assumed that the ideal position for anterior cervical spine plates is centered in the horizontal plane without significant angulation and without overlap of adjacent unfused levels. Nevertheless, postoperative radiographs often demonstrate actual plate position to be lateralized, rotated, or encroaching on the adjacent disc space. There have been no reported systematic studies examining the effect of variations in plate position in a large clinical population. Purpose To evaluate the association between plate position and short-term clinical outcomes after anterior cervical discectomy and instrumented fusion (ACDF). Study design/setting Review of prospectively collected clinical outcomes measures and radiographs. Patient sample Patients undergoing ACDF surgery by a group of spine surgical specialists at a single institution. Outcome measures Direct and calculated plain radiographic measurements, visual analog scores for neck and arm pain, and SF-36 scores. Methods The study population included 200 patients undergoing a one-, two-, or three-level ACDF with instrumentation. Thirteen separate direct measurements and two calculated values of plate position on immediate postoperative radiographs, including lateralization, rotation, and proximity to adjacent disc spaces, were performed in blinded fashion by 3 independent reviewers. Statistical correlation with prospectively collected patient outcomes measures, including VAS for neck and arm pain and SF-36 scores, was performed. Results In the study population, average plate position was 3.3 mm from the cephalad disc space, 6.4 mm from the caudal disc space, 3.9° angulation in the frontal plate, and 26% laterally displaced from the midline. At average 18.6 months of follow-up, no significant association was identified between any plate position measure and clinical outcomes. Conclusions The use of anterior cervical plating by experienced spine surgeons is associated with variation in terms of plate position on postoperative radiographs. Within the range of positions analyzed in this study, no significant association was found between lateralized or rotated plates or plates placed in proximity to adjacent disc spaces and worse short-term clinical outcomes. It should be emphasized that these results and conclusions are based on relatively short-term clinical follow-up and that the long-term effects of variation in implant position remain unknown.

Spine fusion is a common surgical procedure. With or without instrumentation, the hallmark of fusion is the biologic union of adjacent vertebrae. To induce this union, autograft is clearly the standard of bone graft material. However, the limitations and morbidity associated with autograft harvest has led to the search for effective bone graft extenders or alternatives. Potential bone graft materials may be osteoconductive, osteoinductive or osteogenic. They are conceived at the basic science level and then tested in animal models to determine whether clinical application should be considered. Many animal models have been described, ranging from the rat to the nonhuman primate. The more established a model, the more easily the results can be interpreted and placed in the context of existing studies. Depending on the clinical scenario being modeled, different animal models have distinct advantages and disadvantages. Testing is generally done in progressively larger and more advanced species. This stepwise progression of testing establishes the “burden of proof” necessary to justify clinical trials. Many bone graft materials can be thought of as active agents that are combined with a carrier that is usually osteoconductive in nature. It is important to recognize that the active agent, carrier, dose and delivery can all affect the outcome of an attempted fusion. In fact, each variable must be independently considered and optimized. Collagens and synthetic carriers are the most commonly used bone graft carrier materials. However, alternatives such as bioabsorbable implants are under investigation. Demineralized bone matrices (DBMs) are extracts from allogeneic bone. Slurries of resultant molecules such as bone morphogenetic proteins (BMPs) can induce bone formation as classically described by Marshall Urist more than 40 years ago. Depending on the method of preparation, differences

Background Numerous preclinical and clinical studies have reported on the use of platelet concentrates to promote tissue healing. The results in spinal fusion applications are limited and controversial. Purpose The purpose of the current prospective clinical cohort study is to assess the effect of Autologous Growth Factors (AGF) on lumbar interbody fusion with specific attention paid to determination of clinical and radiographic outcomes. Study design/setting Prospective clinical study Patient sample Candidates for anterior-posterior lumbar fusion with diagnosis of degenerative disc disease and/or up to grade I spondylolytic spondylolisthesis based on positive provocative discography. Outcome measures Clinical (visual analogue pain scale/functional outcome assessment) and radiographic outcomes (fusion on computed tomography at 6 months and plain radiographs at 12 and 24 months). Methods Thirty-seven patients were assigned to standard anterior-posterior interbody fusion L2–S1 (single or two-level) using iliac crest bone graft (autograft group: 22 patients with 32 levels operated) or allograft combined with autogenous growth factors (AGF group: 15 patients with 25 levels operated). Radiographic outcomes were collected at 6 months postsurgery with computed tomography and at 12 and 24 months with plain radiographs. Pre- and postoperative clinical outcome measures included visual analog scores (VAS) for back and leg pain (0–10), SF-36 scores, and Oswestry disability determination. Average clinical and radiographic follow-up for the autograft group was 24.3+/−5.6 months (12–36 months) and AGF was 25.7+/−7.5 (6–40 months). Results Fusion incorporation at each end plate was determined at 56% in both autograft and AGF (p=NS) patients based on computed tomography at 6 months with minimal subsidence noted and no direct correlation between the incidence or degree of cage subsidence and bone graft technique. The 12- and 24-month radiographic results confirmed an 85% arthrodesis rate for the autograft patients, whereas the AGF patients had an 89% fusion rate (p=NS). Clinical outcomes were similar for both groups and no significant differences were noted for pain or functional outcome improvements. Conclusions AGF combined with an allograft carrier is equivalent in radiographic and clinical outcomes to autograft in one- or two-level lumbar interbody fusion with supplemental posterior fixation and, thus, eliminates any morbidity from iliac crest bone graft harvesting. AGF combined with an appropriate carrier is a reasonable alternative to autograft and expensive bone induction technologies. Further research is still required to examine the optimum carriers, preparation and formulation, and platelet concentrations for this technology.

STUDY DESIGN Cadaveric human cervical spine anatomic study using posterior lateral mass screw-rod instrumentation to assess foraminal enlargement via distraction techniques. OBJECTIVES To determine the role of posterior cervical distraction on foraminal dimensions and to ascertain the impact of this technique on segmental kyphosis. SUMMARY OF BACKGROUND DATA Management of cervical spondylotic radiculopathy includes removal of offending compressive structures and enlarging the neuroforamen via anterior discectomy with interbody fusion or posterior laminoforaminotomy. METHODS Six human cervical spines were prepared and posterior exposure performed. Lateral mass screws were inserted from C5 to C7 and a longitudinal rod attached. Distraction was applied between the screw heads at 2 mm intervals and accuracy confirmed with digitized calipers. Pre- and postdistraction computed tomography was performed including axial and reformatted images. Foraminal area, height, and width and sagittal alignment and disc heights were evaluated. RESULTS The results suggest that minimal posterior distraction of 4 to 6 mm at C5-C6 and C6-C7 may enlarge the neuroforamen by 10 to 18 mm. Foraminal height and width increased minimally from baseline to maximum distraction; however, these measurements did not reach statistical significance at either level. A decrease of segmental lordosis at C5-C6 was noted from baseline to 8 mm of distraction. Statistically significant kyphosis from baseline was present at 6 mm of distraction leading to overall 5.2 +/- 1.4degrees change in alignment. At C6-C7, statistically significant kyphosis was not present until 8 mm of distraction (4.62 +/- 2.23degrees). CONCLUSIONS This study suggests that posterior cervical instrumented distraction in the setting of foraminal stenosis is a reasonable supplement to direct laminoforaminotomy and nerve root decompression. Distraction leads to minimal segmental kyphosis, allowing this technique to serve as an adjunct for additional foraminal enlargement.

The authors report a patient with delayed inferior thyroid artery pseudoaneurysm after uneventful anterior cervical discectomy and fusion. The Smith-Robinson approach to the anterior cervical spine is a commonly used and relatively safe surgical approach for cervical disc disease. This case is unusual in two respects: 1) the vascular complication occurred 9 days postoperatively; and 2) the inferior thyroid artery was embolized without the need for immediate exploration and surgical ligation. The patient was successfully managed with therapeutic embolization. [Key words: anterior discectomy, embolization, Smith-Robinson approach, vascular complications] Spine 1994;19:1291–1293