Successful Fusion Rate Research Articles

The Impact of Menopause on Bone Fusion after the Single-Level Anterior Cervical Discectomy and Fusion

ObjectiveTo evaluate the successful fusion rate in postmenopausal women with single-level anterior cervical discectomy and successful fusion (ACDF) and identify the significant factors related to bone successful fusion in pre- and postmenopausal women.MethodsFrom July 2004 to December 2010, 108 consecutive patients who underwent single-level ACDF were prospectively selected as candidates. Among these, the charts and radiological data of 39 women were reviewed retrospectively. These 39 women were divided into two groups : a premenopausal group (n=11) and a postmenopausal group (n=28). To evaluate the significant factors affecting the successful fusion rate, the following were analyzed : the presence of successful fusion, successful fusion type, age, operated level, bone mineral density, graft materials, stand-alone cage or plating with autologous iliac bone, subsidence, adjacent segment degeneration, smoking, diabetes mellitus, and renal disease.ResultsThe successful fusion rates of the pre- and postmenopausal groups were 90.9% and 89.2%, respectively. There was no significant difference in the successful fusion rate or successful fusion type between the two groups. In the postmenopausal group, three patients (10.8%) had successful fusion failure. In the postmenopausal group, age and subsidence significantly affected the successful fusion rate (p=0.016 and 0.011, respectively), and the incidence of subsidence in patients with a cage was higher than that in patients with a plate (p=0.030).ConclusionMenopausal status did not significantly affect bone successful fusion in patients with single-level ACDF. However, in older women with single-level ACDF, the combination of use of a cage and subsidence may unfavorably affect successful fusion.

The effects of local insulin application to lumbar spinal fusions in a rat model

The rates of pseudoarthrosis after a single-level spinal fusion have been reported up to 35%, and the agents that increase the rate of fusion have an important role in decreasing pseudoarthrosis after spinal fusion. Previous studies have analyzed the effects of local insulin application to an autograft in a rat segmental defect model. Defects treated with a time-released insulin implant had significantly more new bone formation and greater quality of bone compared with controls based on histology and histomorphometry. A time-released insulin implant may have similar effects when applied in a lumbar spinal fusion model. This study analyzes the effects of a local time-released insulin implant applied to the fusion bed in a rat posterolateral lumbar spinal fusion model. Our hypothesis was twofold: first, a time-released insulin implant applied to the autograft bed in a rat posterolateral lumbar fusion will increase the rate of successful fusion and second, will alter the local environment of the fusion site by increasing the levels of local growth factors. Animal model (Institutional Animal Care and Use Committee approved) using 40 adult male Sprague-Dawley rats. Forty skeletally mature Sprague-Dawley rats weighing approximately 500 g each underwent posterolateral intertransverse lumbar fusions with iliac crest autograft from L4 to L5 using a Wiltse-type approach. After exposure of the transverse processes and high-speed burr decortication, a Linplant (Linshin Canada, Inc., ON, Canada) consisting of 95% microrecrystalized palmitic acid and 5% bovine insulin (experimental group) or a sham implant consisting of only palmitic acid (control group) was implanted on the fusion bed with iliac crest autograft. As per the manufacturer, the Linplant has a release rate of 2 U/day for a minimum of 40 days. The transverse processes and autograft beds of 10 animals from the experimental and 10 from the control group were harvested atDay 4 and analyzed for growth factors. The remaining 20 spines were harvested at 8 weeks andunderwent a radiographic examination, manual palpation, and microcomputed tomographic (micro-CT) examination. One of the 8-week control animals died on postoperative Day 1, likely due to anesthesia. In the groups sacrificed at Day 4, there was a significant increase in insulinlike growth factor-I (IGF-I) in the insulin treatment group compared with the controls (0.185 vs. 0.129; p=.001). No significant differences were demonstrated in the levels of transforming growth factor beta-1, platelet-derived growth factor-AB, and vascular endothelial growth factor between the groups (p=.461, .452, and .767 respectively). Based on the radiographs, 1 of 9 controls had a solid bilateral fusion mass, 2 of 9 had unilateral fusion mass, 3 of 9 had small fusion mass bilaterally, and 3 of 9 had graft resorption. The treatment group had solid bilateral fusion mass in 6 of 10 and unilateral fusion mass in 4 of 10, whereas a small bilateral fusion mass and graft resorption were not observed. The difference between the groups was significant (p=.0067). Based on manual palpation, only 1 of 9 controls was considered fused, 4 of 9 were partially fused, and 4 of 9 were not fused. In the treatment group, there were 6 of 10 fusions, 3 of 10 partial fusions, and 1 of 10 were not fused. The difference between the groups was significant (p=.0084). Based on the micro-CT, the mean bone volume of the control group was 126.7 mm(3) and 203.8 mm(3) in the insulin treatment group. The difference between the groups was significant (p=.0007). This study demonstrates the potential role of a time-released insulin implant as a bone graft enhancer using a rat posterolateral intertransverse lumbar fusion model. The insulin-treatment group had significantly higher fusion rates based on the radiographs and manual palpation and had significantly higher levels of IGF-I and significantly more bone volume on micro-CT.

Results After Radioscapholunate Arthrodesis With or Without Resection of the Distal Scaphoid Pole

To evaluate the differences between radioscapholunate (RSL) arthrodesis alone versus RSL arthrodesis with additional distal scaphoidectomy. We retrospectively evaluated 61 patients who were treated with RSL arthrodesis for painful posttraumatic osteoarthritis. Thirty patients had an RSL arthrodesis with additional resection of the distal scaphoid pole (group A), and 31 had RSL arthrodesis alone (group B). Six patients in group A and 8 in group B had the RSL arthrodesis converted to a complete wrist arthrodesis during follow-up. Those patients were excluded from the survey. Of the remaining 47 patients, 35 (20 from group A, 15 from group B) returned for a clinical and radiological examination at an average of 28 (range, 10-47) months after the index surgery. The results were rated by the Disabilities of the Arm, Shoulder, and Hand score and the modified Mayo Wrist Score. The patients' outcomes after RSL arthrodesis with or without distal scaphoidectomy were compared for pain, wrist motion, grip strength, nonunion rate, osteoarthritis of the adjacent joints, the Disabilities of the Arm, Shoulder, and Hand score and the modified Mayo Wrist Score. Three patients with RSL arthrodesis alone showed a radioscaphoid nonunion. All arthrodeses in group A healed. In the clinical evaluation, there was no significant difference between groups A and B in the Disabilities of the Arm, Shoulder, and Hand score, the modified Mayo Wrist Score, grip strength, pain, or wrist motion. Assuming that wrist motion might be better in patients with a nonunion, the average wrist motion was recalculated after eliminating 3 patients with a radioscaphoid nonunion from group B. Radial deviation was then found to be significantly better in group A. Additional distal scaphoidectomy with RSL arthrodesis seems to improve postoperative radial deviation of the wrist. The radioscaphoid nonunion rate is high with RSL arthrodesis alone. Distal scaphoidectomy appeared to increase the successful fusion rate of RSL arthrodeses. No significant effect on wrist extension, flexion, ulnar deviation, pain level, restriction in activities of daily living, or grip strength was noted.

Comparison of safety and stability of C-2 pars and pedicle screws for atlantoaxial fusion: meta-analysis and review of the literature

Some centers report a lower incidence of vertebral artery (VA) injury with C-2 pars screws compared with pedicle screws without sacrificing construct stability, despite biomechanical studies suggesting greater load failures with C-2 pedicle screws. The authors reviewed published series describing C-2 pars and pedicle screw implantation and atlantoaxial fusions and compared the incidence of VA injury, screw malposition, and successful atlantoaxial fusion with each screw type. Online databases were searched for English-language articles between 1994 and April of 2011 describing the clinical and radiographic outcomes following posterior atlantoaxial fusion with C-1 lateral mass and either C-2 pars interarticularis or pedicle screws. Thirty-three studies describing 2975 C-2 pedicle screws and 11 studies describing 405 C-2 pars screws met inclusion criteria for the safety analysis. Seven studies describing 113 patients treated with C-2 pars screws and 20 studies describing 918 patients treated with C-2 pedicle screws met inclusion criteria for fusion analysis. Standard and formal meta-analysis techniques were used to compare outcomes. All studies provided Class III evidence. Ten instances of VA injury occurred with C-2 pedicle screws (0.3%) and no VA injury occurred with pars screws. The point estimate of VA injury for C-2 pedicle screws was 1.09% (95% CI 0.73%-1.63%) and was similar to that of C-2 pars screws (1.48%, 95% CI 0.62%-3.52%). Similarly, there was no statistically significant difference in the rate of clinically significant screw malpositions (1.14% [95% CI 0.77%-1.69%) vs 1.69% [95% CI 0.73%-3.84%]). Radiographically identified screw malposition occurred in a higher proportion of C-2 pedicle screws compared with C-2 pars screws (6.0% [95% CI 3.7%-9.6%] vs 4.0% [95% CI 2.0%-7.6%], p < 0.0001). Pseudarthrosis occurred in a greater proportion of patients treated with C-2 pars screws (5 [4.4%] of 113) compared with those treated with C-2 pedicle screws (2 [0.22%] of 900). Point estimates with 95% confidence intervals show a slightly higher rate of successful atlantoaxial fusion in the pedicle screw cohort (97.8% [CI 96.0%-98.8%] vs 93.5% [CI 86.6%-97.0%]; p < 0.0001). Q-testing ruled out heterogeneity between the study groups. With a thorough knowledge of axis anatomy, surgeons can place both C-2 pars and C-2 pedicle screws accurately with a small risk of VA injury or clinically significant malposition. There may be subtle trade-off of safety for rigidity when using axial pedicle instead of pars screws, and the decision to use either screw type must be made only after careful review of the preoperative CT imaging and must take into account the surgeon's expertise and the particular demands of the clinical scenario in any given case.

The Effects of Local Insulin Application to Lumbar Spinal Fusions in a Rat Model

BACKGROUND CONTEXT: The rates of pseudoarthrosis after a single-level spinal fusion have been reported up to 35%, and the agents that increase the rate of fusion have an important role in decreasing pseudoarthrosis after spinal fusion. Previous studies have analyzed the effects of local insulin application to an autograft in a rat segmental defect model. Defects treated with a timereleased insulin implant had significantly more new bone formation and greater quality of bone compared with controls based on histology and histomorphometry. A time-released insulin implant may have similar effects when applied in a lumbar spinal fusion model. PURPOSE: This study analyzes the effects of a local time-released insulin implant applied to the fusion bed in a rat posterolateral lumbar spinal fusion model. Our hypothesis was twofold: first, a time-released insulin implant applied to the autograft bed in a rat posterolateral lumbar fusion will increase the rate of successful fusion and second, will alter the local environment of the fusion site by increasing the levels of local growth factors. STUDY DESIGN: Animal model (Institutional Animal Care and Use Committee approved) using 40 adult male Sprague-Dawley rats. METHODS: Forty skeletally mature Sprague-Dawley rats weighing approximately 500 g each underwent posterolateral intertransverse lumbar fusions with iliac crest autograft from L4 to L5 using a Wiltse-type approach. After exposure of the transverse processes and high-speed burr decortication, a Linplant (Linshin Canada, Inc., ON, Canada) consisting of 95% microrecrystalized palmitic acid and 5% bovine insulin (experimental group) or a sham implant consisting of only palmitic acid (control group) was implanted on the fusion bed with iliac crest autograft. As per the manufacturer, the Linplant has a release rate of 2 U/day for a minimum of 40 days. The transverse processes and autograft beds of 10 animals from the experimental and 10 from the control group were harvested at Day 4 and analyzed for growth factors. The remaining 20 spines were harvested at 8 weeks and underwent a radiographic examination, manual palpation, and microcomputed tomographic (micro-CT) examination. RESULTS: One of the 8-week control animals died on postoperative Day 1, likely due to anesthesia. In the groups sacrificed at Day 4, there was a significant increase in insulinlike growth factor-I (IGF-I) in the insulin treatment group compared with the controls (0.185 vs. 0.129; p5.001). No significant differences were demonstrated in the levels of transforming growth factor beta-1,

Feasibility of C2 Translaminar Screw as an Alternative or Salvage of C2 Pedicle Screws in Atlantoaxial Instability

A retrospective outcome study. The purpose of this study was to analyze the clinical outcomes of our experience with the C2 translaminar screw technique and evaluate its feasibility as an alternative or salvage of the pedicle screw. Pedicle screws are the most biomechanically stable screws for use in atlantoaxial fixation. However, in cases with elevated risk of neurovascular complications or failure of screw insertion attempts, a reliable alternative technique is required. Fourteen patients with atlantoaxial instability underwent posterior fixation with C2 translaminar screws. Indications included traumatic instability, atlantoaxial subluxation, os odontoideum, and fusion failure after anterior fixation of a type II odontoid process fracture. A total of 26 screws were inserted and all patients were assessed both clinically and radiographically. No procedure-related complications or hardware failures were observed during the follow-up. Postoperative computed tomographic scans revealed laminar breach in 3 patients and none of these resulted in neurological symptoms. Radiographically demonstrated bony fusion was established in 11 patients (91.7%) at follow-up over 6 months, and 5 patients with initial neurological deficit demonstrated at least 1 grade improvement by Frankel grade. C2 translaminar screws provide surgeons with an expanded option for posterior fusion in high cervical lesions. This technique is safe and easy to adopt with a favorable rate of successful fusion. We believe that preoperative planning using computed tomographic scan is mandatory and use of an additional connector may reduce the stress and strain of the screws.

C1-C2 fusion: postoperative C2 nerve impingement—is it a problem?

Objective: The purpose of this comparison case study is to show a potential complication associated with atlantoaxial fusion, and the preoperative evaluation that could help to avoid it.Background data: The use of lateral mass screw fixation in atlantoaxial fusion has provided surgeons the ability to create rigid fixation, with a high success rate of fusion. While the use of screws for fixation is relatively easy to adopt, the risk of causing neurological damage to the patient is ever present. Many major structures, such as the vertebral artery, carotid artery, and spinal cord, must all be considered during surgery.Methods: A comparison of two patients who underwent the same procedure was reviewed—the first had no complications from surgery and the second underwent revision surgery because of the C1 screw impinging on the C1 nerve exiting the foramen.Results: After removal of the C1 screw and converting to a cable technique, the patient made a full recovery and neurological function was restored.Conclusions: When considering C1-C2 lateral mass screw fixation for atlantoaxial fusion, the size of the foramen should be considered. If the foramen is significantly narrowed, alternate fixation should be selected.

Anterior Reconstruction With Nano-hydroxyapatite/polyamide-66 Cage After Thoracic and Lumbar Corpectomy

Cages are used to regain stability of the anterior spinal column following vertebrectomy, which could prevent significant donor-site morbidity from the iliac autograft harvesting and the risk of disease transmission associated with the allograft. The hollow, porous, cylindrical nanohydroxyapatite/polyamide 66 (n-HA/PA66) cage is a new nonmetallic cage device made by combining nanohydroxyapatite with polyamide 66. Few studies have examined its effectiveness and outcomes over a follow-up >2 years.We retrospectively studied 51 consecutive patients with acute traumatic thoracic or lumbar burst fracture who underwent anterior reconstruction with the n-HA/PA66 cage following single-level corpectomy. Radiologic parameters (radiographs and 3-dimensional computed tomography scans) preoperatively and at 1 week and >2 years postoperatively, as well as clinical outcome parameters (SF-36 scores), were analyzed. Mean kyphosis correction in the segment within the cage was 11.8°±7.1°, and mean loss of correction at last follow-up was 1.9°±2.1°. Osseous fusion was achieved in 90.2% of patients, and severe cage subsidence (settling >2 mm) was observed in 19.6% of patients at final follow-up. Significant differences were found in 7 of 8 health dimensions of the SF-36 between neurologically intact patients and neurologically injured patients. Our clinical results indicate that the n-HA/PA66 cage is an effective device for reconstruction after anterior thoracic and lumbar vertebral resection, resulting in a high rate of successful osseous fusion and a low proportion of severe cage subsidence.

Direct Pars Repair Surgery Using Two Different Surgical Methods : Pedicle Screw with Universal Hook System and Direct Pars Screw Fixation in Symptomatic Lumbar Spondylosis Patients

ObjectiveThe authors performed a retrospective study to assess the clinical and radiological outcome in symptomatic lumbar spondylolysis patients who underwent a direct pars repair surgery using two different surgical methods; pedicle screw with universal hook system (PSUH) and direct pars screw fixation (DPSF), and compared the results between two different treated groups.MethodsForty-seven consecutive patients (PSUH; 23, DPSF; 15) with symptomatic lumbar spondylolysis who underwent a direct pars repair surgery were included. The average follow-up period was 37 months in the PSUH group, and 28 months in the DPSF group. The clinical outcome was measured using visual analogue pain scale (VAS) and Oswestry disability index (ODI). The length of operation time, the amount of blood loss, the duration of hospital stay, surgical complications, and fusion status were also assessed.ResultsWhen compared to the DPSF group, the average preoperative VAS and ODI score of the PSUH group were less decreased at the last follow-up; (the PSUH group; back VAS : 4.9 vs. 3.0, leg VAS : 6.8 vs. 2.2, ODI : 50.6% vs. 24.6%, the DPSF group; back VAS : 5.7 vs. 1.1, leg VAS : 6.1 vs. 1.2, ODI : 57.4% vs. 18.2%). The average operation time was 174.9 minutes in the PSUH group, and 141.7 minutes in the DPSF group. The average blood loss during operation was 468.8 cc in the PSUH group, and 298.8 cc in the DPSF group. The average hospital stay after operation was 8.9 days in the PSUH group, and 7 days in the DPSF group. In the PSUH group, there was one case of a screw misplacement requiring revision surgery. In the DPSF group, one patient suffered from transient leg pain. The successful bone fusion rate was 78.3% in the PSUH group, and 93.3% in the DPSF group.ConclusionThe present study suggests that the technique using direct pars screw would be more effective than the method using pedicle screw with lamina hook system, in terms of decreased operation time, amount of blood loss, hospital stay, and increased fusion success rate, as well as better clinical outcome.

Five-Year Follow-Up for B-Twin Cage Spinal Fusion

Posterior lumbar inter-body fusion (PLIF) is a surgical intervention suitable to disco-genic low back pain with or without radiculopathy. Studies reviewing expected spinal fusion success rates for conventional PLIF range from 70–90%. Symptomatic improvement in cases of conventional PLIF has been reported as 70%. In the below study we compare the results of a new inter-body fusion device called the B-twin expandable spinal spacer to accepted results for standard PLIF techniques.

Trephine transcutaneous osteotomy of talonavicular arthrodesis in the treatment of talonavicular pain

Objective To evaluate the clinical effect of talonavicular arthrodesis and the influence of adjacent joints use trephine percutaneous osteotomy in the treatment of talonavicular arthralgia.Methods From June 1999 to June 2009,24 patients were performed talonavicular arthrodesis due to a variety of painful disorder of talonavicular joint with trephine percutaneous osteotomy.There were 13 males and 11 females,with an average age of 45 years(range,37-72 years).The indications for the procedure included 15cases with posttraumatic arthritis,6 cases with rheumatoid arthritis,and 3 cases with degenerative arthritis.AOFAS system and visual analogue scale(VAS)were used to evaluate the change of function and arthralgia.Graves score system was used to evaluate the influence of adjacent joints.Results All patients were followed up 10-120 months,with the mean of 48 months.Only one case suffered skin brim necrosis of incision and got delayed healing after 3 weeks.The average AOFAS ankle-hind foot score improved from 45.2 points preoperatively to 84.5 points postoperatively.The excellent and good rate was 87.5%.VAS pain scores decreased from 8.1 to 2.4 postoperatively.Twenty-three patients were satisfied and one dissatisfied with the results.Postoperative radiology showed the union evidence in 23 patients at 6 months postoperatively(successful fusion rate of 95.8%).One joint nonunion occurred and required revision arthrodesis with iliac crest bone graft.There was an increase of Ⅰ grade in arthritic scores for 8 cases and Ⅱ grade for 1 case.Conclusion Talonavicular arthrodesis with trephine percutaneous osteotomy has the advantages of low trauma,high successful fusion rate and can acquire satisfactory clinical effect in the treatment of painful malalignment of talonavicular joints. Key words: Arthrodesis; Talus; Scaphoid; Pain

High-Dose Ketorolac Affects Adult Spinal Fusion

Meta-analysis of literature. To evaluate the effect of perioperative nonsteroidal anti-inflammatory drugs (NSAIDs) on the success rate of adult spinal fusion. NSAIDs are commonly used to treat postsurgical orthopedic pain. Studies on animal models have shown a significant inhibiting effect of NSAIDs on osteogenesis process, on which spinal fusion also depends. Recently, great interest has been shown in the effect of NSAIDs on the success rate of adult spinal fusion. Clinical trials have tested the effect of perioperative NSAIDs in spinal fusion procedures. A cumulative result of these studies would give more credit to the final conclusions. A systematic search of electronic databases and references from eligible articles was conducted. Comparative studies reporting on the results of primary spinal fusion including treatment group of NSAIDs perioperatively were regarded eligible. A pooled estimate of effect size was produced using both random and fixed effect model. Five retrospective comparative studies (n = 1403 participants) were included in the present study. The mean age of these patients was more than 40 years and none of them had NSAIDs for longer than 14 days following spinal fusion surgery. High-dose ketorolac showed a statistically significant adverse effect on spinal fusion (P = 0.001, RR = 2.87, 95% CI = 1.53 = - 5.38) with no statistical heterogeneity (I = 3%, P = 0.38), whereas normal-dose NSAIDs (ketorolac, diclofenac sodium, celecoxib, or rofecoxib) did not appear to produce inferior results than the no-NSAIDs group (P = 0.30, RR = 1.39, 95% CI = 0.74 - 2.61) with no statistical heterogeneity (I² = 0%, P = 0.50). Although randomized controlled trials would be optimal for meta-analyses, the data of this review revealed that short-time (<14 days) exposure to normal-dose NSAIDs (ketorolac, diclofenac sodium, celecoxib, or rofecoxib) were safe after spinal fusion, whereas short-time (<14 days) exposure to high-dose ketorolac increased the risk of nonunion, which meant that the effect of perioperative NSAIDs on spinal fusion might be dose-dependent. Further studies would be needed to find out whether long-time exposure to normal-dose NSAIDs could also increase the risk of nonunion and which type of NSAIDs would like to have a worse effect on spinal fusion.

Low-Intensity Pulsed Ultrasound Enhances Healing of Laminectomy Chip Bone Grafts on Spinal Fusion: A Model of Posterolateral Intertransverse Fusion in Rabbits

Laminectomy-derived chip bone graft was usually used in spinal fusion; however, the result of this kind of local bone used in lumbar posterolateral fusion is uncertain. This study tested the hypotheses that low-intensity pulsed ultrasound (LIPU) can accelerate the healing process of laminectomy bone chips in a spinal fusion and enhance the union rate. Forty-eight rabbits were randomly divided into three groups for the spinal unilateral uninstrumented posterolateral fusion of L5-L6: autologous iliac bone graft (AIBG), laminectomy chip bone graft (LCBG), LCBG plus LIPU (LCBG + LIPU). Each group was subdivided into 6-week and 12-week subgroups. All rabbits were subjected to radiographic examination and manual testing. All successful spinal fusion specimens received biomechanical testing and a histologic examination. The LCBG + LIPU group had the highest successful fusion rate at 6-week and 12-week examination (75% and 100%, respectively). At 6 weeks, the average maximum toque at failure values of the fusion masses for the LCBG + LIPU group was significantly higher than that for the LCBG group (p = 0.034). The average maximum torque of the 12-week LCBG + LIPU group was significantly higher than those of the 12-week AIBG and 12-week LCBG groups (p = 0.040 and p = 0.026, respectively). This study suggested that LIPU can enhance bone healing. With augmentation by LIPU, laminectomy chip bone used in lumbar posterolateral fusion can achieve a similar fusion rate and stronger fusion mass than those of an AIBG.

Outcomes of Interbody Fusion Cages Used in 1 and 2-levels Anterior Cervical Discectomy and Fusion

A prospective study was performed in case with cervical spondylosis who underwent anterior cervical discectomy and fusion (ACDF) with titanium or polyetheretherketone (PEEK) cages. To find out which fusion cage yielded better clinical and radiographic results. Although use of autogenous iliac-bone grafts in ACDF for cervical disc diseases remain standard surgical procedure, donor site morbidity and graft collapse or breakage are concerns. Cage technology was developed to prevent these complications. However, there is no comparison regarding the efficacy between titanium and PEEK cage. January 2005 to January 2006, 53 patients who had 1 and 2-levels ACDF with titanium or PEEK cages were evaluated. We measured the rate and amount of interspace collapse, segmental sagittal angulations, and the radiographic fusion success rate. Odom criteria were used to assess the clinical results. The fusion rate was higher in the PEEK group (100% vs. 86.5%, P=0.0335). There was no significant difference between both groups in loss of cervical lordosis (3.2 + or - 2.4 vs. 2.8 + or - 3.4, P=0.166). The mean anterior interspace collapse (1.6 + or - 1.0 mm) in the titanium group was significantly higher than the collapse of the PEEK group (0.5 + or - 0.6 mm) (P<0.0001). The mean posterior interspace collapse was also higher in the titanium group (1.6 + or - 0.9 mm vs. 0.5 + or - 0.5 mm, P<0.0001). An interspace collapse of 3 mm or greater was observed in 16.2% of the patients in the titanium group, compared with zero patients in the PEEK group (P<0.0001). The PEEK group achieved an 80% rate of successful clinical outcomes, compared with 75% in the titanium group (P=0.6642). The PEEK cage is superior to the titanium cage in maintaining cervical interspace height and radiographic fusion after 1 and 2-levels anterior cervical decompression procedures.

Clinical and radiologic outcome of laminar screw at C2 and C7 for posterior instrumentation—review of 25 cases and comparison of C2 and C7 intralaminar screw fixation

Background The aim of this study is 2-fold: to analyze a clinical case series in which we used laminar screws for cervical posterior instrumentation and to describe the difference between C2 and C7 laminar screws in terms of technique and anatomy. Methods Data were obtained from 25 patients who underwent cervical posterior fixation with intralaminar screws at C2 or C7. C2 intralaminar screw instrumentation was used for 7 patients requiring occipitocervical fixation (basilar invagination [3 patients], C1 unstable bursting fracture [1 patient], C1-C2 instability with occipital assimilation [2 patients], and dystopic os odontoideum [1 patient]), 13 patients with C1-C2 instability, 1 patient with C2-C3 subluxation, and 4 patients undergoing C7 fixation due to pseudoarthrosis or cervical instability after trauma. A total of 34 laminar screws were placed including 1 thoracic laminar screw, and the patients were assessed both clinically and radiographically. Results There were no instances where a screw violated the spinal canal nor any hardware fractures noted during the follow-up period. As for perioperative complications, there were 2 cases of postoperative wound infection, 1 case of dural laceration during dissection, and 2 cases of partial dorsal laminar breach. However, there was no neurologic compromise in any of the cases. The fusion success rate was 100%. Conclusion These preliminary results support the use of intralaminar screws for posterior instrumentation at C2 and C7.

Pseudarthrosis of the Spine

Pseudarthrosis is the result of failed attempted spinal fusion. This condition typically manifests with axial or radicular pain months to years after the index operation. Diagnosis is based on clinical presentation and imaging studies, after other causes of persistent pain are ruled out. The degree of motion seen on flexion-extension radiographs that is indicative of solid or failed fusion remains a point of controversy. Thin-cut CT scans may be more reliable than radiographs in demonstrating fusion. Metabolic factors, patient factors, use and choice of instrumentation, fusion material, and surgical technique have all been shown to influence the rate of successful fusion. Treatment of the patient with symptomatic pseudarthrosis involves a second attempt at fusion and may require an approach different from that of the index surgery as well as the use of additional instrumentation, bone graft, and osteobiologic agents.

Uninstrumented posterolateral spinal arthrodesis: is it the gold standard technique for I° and II° grade spondylolisthesis in adolescence?

We retrospectively reviewed the outcome of uninstrumented posterolateral spinal arthrodesis in 49 patients with lumbar isthmic spondylolisthesis grades I degrees and II degrees in adolescent patients in the time of surgery, who participate at follow-up, between 1980 and 1995. The goal of our study is to analyse the clinical and radiographic imaging at long follow-up in uninstrumented posterolateral arthrodesis and to evaluate the efficiency and the validity of surgical technique in young patients (<18 years). All patients had failed previous conservative treatment. The average age at follow-up was 33.5 years (range 25-42 years) and the average follow-up time was 19.7 years (range 12-27 years). The clinical outcome measures were the Oswestry Disability Index, the SF-36, and the visual analogic score. All measures assessed the endpoint outcomes at 20 years after surgery. The outcome of spinal fusion was good with 43 (87.7%) patients attaining solid fusion, pseudoarthrosis in 6 patients (12.3%). None of our patients complained of excessive postoperative wound pain. Additionally, no complications, such as wound infection, were encountered. Satisfactory results were obtained in 94% of patients and this was closely associated with the rate of successful fusion. The results suggest that clinical outcome is closely related to the attainment of solid fusion.

Three-Level Anterior Cervical Discectomy and Fusion with Plate Fixation: Radiographic Results of 127 Patients

Study Design. A retrospective radiographic review of all patients treated by a single surgeon with a three-level anterior cervical discectomy and fusion with plate fixation. Objectives. To compare fusion success rates and pseudoarthrosis results with published data for three-level anterior cervical constructs including; anterior cervical discectomy and fusion with plating (ACDFP) and anterior cervical corpectomy with and without plating (ACCP, ACC). Methods. In this study, authors have reviewed a series of 1416 patients done by a single surgeon between May 2001 and February 2008. Of these, 127 patients met standard criteria including a minimum of six months follow up, no previous cervical surgeries, and flexion/extension lateral radiographs. Pseudoarthrosis was defined as abnormal movement between the spinous processes, lucency at the graft vertebral body interface or absence of trabecular bone spanning the complete fused space. Fusion was identified by the absence of abnormal motion of the fused segments on flexion/extension lateral radiographs and the presence of continuous trabecular bone formation at the graft/endplate junction. Results. Of the 127 patients, 124 had successful fusions and 3 had pseudoarthrosis. Three hundred seventy-six out of three-hundred eighty-one (98.7%) levels fused while only five (1.3%) levels developed pseudoarthrosis. Conclusions. This study presents the largest reported series of patients undergoing a three-level ACDFP by a single surgeon with close follow up, and suggests that three-level ACDFP utilizing a standardized modified Smith-Robinson technique has an acceptably high level of fusion in comparison to other modalities.

Lumbosacral Fusion: The Mortised Transfacet Method by Use of the Vibrating Electric Saw for Circular Bone Blocks Earl D. McBride MD, Howard B. Shorbe MD CORR 1958;12:268-275

Reliably achieving spine fusion has been a problem since fusion was first described by Russell Hibbs of the New York Orthopaedic Hospital in 1911 [1]. Since that time, many dozens, if not hundreds of techniques have been proposed. PubMed lists over 1700 articles on the topic since 1935, many of which relate to techniques, and these 1700 articles undoubtedly reflect the tip of the iceberg. The reasons for performing a spine fusion have also varied and been greatly refined over the last century, and the success rates have varied depending, in addition to other factors, on both the reasons for the fusion and the technique. The article we highlight this month on lower lumbar spine fusion was published by Dr. Earl McBride and his colleague, Dr. Howard Shorbe, both of Oklahoma City [5]. Dr. McBride had been the founder and first President of the Association of Bone and Joint Surgeons (1947) [2, 3] which organized and has sponsored this journal since its inception in 1953. McBride and Shorbe noted, “a successful fusion depends on where and how the bone graft is implanted, not upon the amount of bone utilized” [5]. One of the more common reasons for surgery at the time was a ruptured disc, and they commented, “Removal of the offending disk protrusion alone is not likely to relieve the residual effects of progressive arthritic erosion and ligamentous weakness. How can such facts be ignored so completely?” [5] Their proposal was to fuse the facet joints, which often were arthritic in advance cases, using a dowel grafts cut by trephines on a vibrating saw and inserting those grafts into similar size cylindrical hole across the fact joints. They commented, “The nerve will not be damaged by the saw if it is directed properly and if correct depth adjustment has been made” [5]. Although mentioned in but a single sentence, this same point has been emphasized the past ten years or so with pedicle screws placed across the facet joints to achieve the same purpose: directing an implant in the proper direction requires great skill and knowledge. McBride and Shorbe [5] were not uniformly successful in achieving fusion: their rate of successful lumbar fusion was 91% at the L5-S1 level. When they operated on two levels, their rates of success were much lower: 65% at both levels. They noted, however, a successful fusion seen on a radiograph did not necessarily correlate with improvement of the patient: “…good and fair clinical healing was obtained in 97 percent of the total cases” [5]. They did not have the sophisticated instruments we do today in assessing success, and undoubtedly a contemporary assessment would lead to a lower clinical success rate. Nonetheless, their finding that successful bone fusion did not predict clinical outcome is consistent with a more recent report with the same finding in patients who had multiple back operations and other sorts of fusion [4]. Thus, their conclusion, “Satisfactory clinical results of facet graft fusions have always exceeded the number of cases showing solid bony union” [5] likely holds today.

Posterolateral lumbar spine fusion using a novel demineralized bone matrix: a controlled case pilot study

Intertransverse posterolateral fusion along with instrumentation is a common technique used for spinal fusion. Iliac crest bone graft (ICBG) offers good fusion success rates with a low risk for disease transmission but is, however, linked with certain morbidity. In an effort to eliminate or reduce the amount of iliac graft needed, bone substitutes including demineralized bone matrix (DBM) have been developed. This study evaluates a novel DBM (Accell Connexus used in one or two-level instrumented posterolateral lumbar fusion. A total of 59 consecutive patients were studied as two groups. Group 1 consisted of 33 patients having Accell Connexus used to augment either ICBG or local decompression material. Group 2 consisted of 26 consecutive patients, operated prior to the introduction of this novel DBM, having either ICBG alone or local decompression material. Fusion was assessed by two independent observers, blinded to graft material, using standardized criteria found in the literature. All adverse events were recorded prospectively. The results show no statistically significant differences between the two groups in fusion rates, complications, surgery duration, ODI, or pain on VAS. Logistical regression showed no relation between fusion and age, smoking status or comorbidities. Furthermore, no adverse events related to the use of the novel DBM were observed. The results from this study demonstrate that the novel DBM presented performs equally as well as that of autologous bone, be it either ICBG or a local decompression material, and can therefore be used as a graft extender.