Allograft bone in spinal fusion for adolescent idiopathic scoliosis

Fusion rates based on type of bone graft substitute using minimally invasive scoliosis surgery for adolescent idiopathic scoliosis

BACKGROUND

Minimally invasive scoliosis surgery (MISS) is currently introduced on novel technique for surgical treatment of adolescent idiopathic scoliosis (AIS). This study is aimed to evaluate the efficacy of facet fusion in MISS compared to posterior fusion in conventional open scoliosis surgery (COSS) and compare facet fusion rates based on three bone graft substitutes in MISS for adolescent idiopathic scoliosis (AIS).

METHODS

Eighty six AIS patients who underwent scoliosis surgery were divided into two groups: the COSS group and the MISS group. COSS was performed through posterior fusion with allograft. MISS was applied via facet fusion with three bone graft substitutes. The MISS group was further divided into three subgroups based on graft substitute: Group A (allograft), Group B (demineralized bone matrix [DBM]), and group C (demineralized cancellous bone chips). Fusion rate was measured using conventional radiographs to visualize loss of correction > 10°, presence of lysis around implants, breaks in fusion mass, and abnormal mobility of the fused segment.

RESULTS

The fusion rates showed no significant difference in COSS and MISS groups (p = 0.070). In the MISS group, the fusion rates were 85, 100, and 100% in groups A, B, and C, respectively, with no significant difference (p = 0.221). There were no statistical differences between groups A, B, and C in terms of correction rate, fusion rate, and SRS-22 scores (p > 0.05).

CONCLUSIONS

The facet fusion in MISS showed comparable to posterior fusion in COSS with regard to radiological and clinical outcomes. Furthermore, the type of graft substitute among allograft, DBM, and demineralized cancellous bone chips did not affect facet fusion rate or clinical outcomes in MISS. Therefore, MISS showed comparable fusion rate (with no influences on the type of graft substitute) and clinical outcomes to those of COSS in the surgical treatment of AIS.

Use of graft materials and biologics in spine deformity surgery: a state-of-the-art review

PURPOSE

The aim of the current review is to summarize the current evidence on graft materials used in fusion procedures for spinal deformity corrections.

METHODS

PubMed, Embase, and Cochrane Library were searched for relevant published observational studies and clinical trials using osteobiologics and biomaterials in spinal deformity surgery.

RESULTS

The use of autograft in deformity correction surgeries has been reported in a limited number of studies, with the harvest sites including iliac crest, ribs, and local bone. Various allografts and biologics have been used in the treatment of spinal deformities including idiopathic and degenerative scoliosis, either as stand alone or in combination with autograft. Limited number of studies reported no differences in fusion rates or outcomes. Use of rh-BMP2 in anterior, posterior or front/back approaches showed higher fusion rates than other graft materials in patients with spinal deformities. Due to the limited number of quality studies included in the review, as well as alternative factors, such as costs, availability, and surgeon expertise/preference, no definitive conclusion or recommendations can be made as to the ideal graft choice in spinal deformity surgery.

CONCLUSIONS

Most commonly used grafts included autograft, allograft and rh-BMP2, with new biologics and biomaterials constantly emerging in the market. Limited number of high-quality comparative studies and heterogeneity in study design prevented direct comparisons that can lead to meaningful recommendations. Further studies are needed to prove superiority of any single graft material and/or biologic that is also cost-effective and safe.

The Current Practice of Adult Idiopathic Scoliosis Surgical Treatment Among Spine Surgeons in Saudi Arabia

Background: Scoliosis is a spinal deformity consisting of lateral curvature and rotation of the vertebrae. The goal of corrective scoliosis surgery is to restore alignment of the spine and maintain motion. However, there is no global agreement among spine surgeons on the best method of surgical intervention, and little is known about the variations in practice among spine surgeons in Saudi Arabia.

Objectives: The aim of this study is to examine the current surgical practices relating to adolescent idiopathic scoliosis and to establish the degree of variation and consensus among spine surgeons in Saudi Arabia.

Methods: This was a cross-sectional study conducted among spine surgeons in Saudi Arabia, using a self-administered questionnaire. The questionnaire addressed four areas: surgeons’ demographics, pre-operative assessment, operative assessment, and infection control practices. There were a total of 27 questions. Data was analyzed using statistical package for social sciences (SPSS) software (SPSS Inc., Chicago, IL, USA).

Results: A total of 150 surgeons were included in this study. Of these, 73 responded to the questionnaire (response rate: 48.6%), 46 (63.01%) of whom were fellows. All respondents were males, and 37 (51.39%) were aged between 30 and 40 years. Fifty five (75.34%) were orthopedic surgeons. The most commonly used pre-operative health assessment test was an echocardiogram. Sixty six (90%) surgeons requested scoliosis anteroposterior (AP) view and lateral radiograph for curvature between 40 degrees and 90 degrees, and 65 (89%) requested it for curvature greater than 90 degrees. For the posterior construct, 29 (45.31%) did not use cross-links for fewer than 10 levels, and 23 (35.94%) did not use cross-links for more than 10 levels. In addition to a local bone graft, the most commonly used transplant method was allograft 37 (50.68%). Fifty five (85.94%) respondents favored an all-screw pedicle construct over a hybrid construct.

Conclusion: A large variation in surgical practices was observed. This was especially apparent in practices including the use of cross-links, intra-operative cell salvage, and the intra-operative use of traction. Some degree of variation was observed in pre-operative imaging assessment practices. Surgical guidelines should be developed to build a consensus among surgeons. A unified surgical training curriculum may help in achieving this goal.

Consensus on Implants in Infections After Spine Surgery

In July of 2018, the Second International Consensus Meeting (ICM) on Musculoskeletal Infection convened in Philadelphia, PA was held to discuss issues regarding infection in orthopedic patients and to provide consensus recommendations on these issues to practicing orthopedic surgeons. During this meeting, attending delegates divided into subspecialty groups to discuss topics specifics to their respective fields, which included the spine. At the spine subspecialty group meeting, delegates discussed and voted upon the recommendations for 63 questions regarding the prevention, diagnosis, and treatment of infection in spinal surgery. Of the 63 questions, 9 focused on implants questions in spine surgery, for which this article provides the recommendations, voting results, and rationales.

The clinical use of the enriched bone marrow obtained by selective cell retention technology in treating adolescent idiopathic scoliosis

Purpose

This retrospective study aimed to evaluate the curative effect of allografts in combination with bone marrow enrichment realised by selective cell retention (SCR) technology in treating adolescent idiopathic scoliosis (AIS).

Methods

From July 2014 to September 2016, 18 consecutive patients with AIS were treated by posterior fusion and pedicle screw instrumentation. Bone marrow aspirates were obtained and enriched by SCR technology to fabricate bone grafts in combination with allogeneic bones, which were implanted for spinal fusion. Postoperatively, the patients were observed for a minimum of 18 months, with a mean follow-up period of 48 months. The results were assessed both clinically and radiographically. All adverse events and complications were recorded.

Results

A total of 9 male and 9 female patients were included, with an average age of 15.6 years (range, 12–20). The average preoperative Cobb angle was 56° (range, 47°–85°). The average number of levels fused was 11 (range, 9–13). SCR could be accomplished intraoperatively, only consuming approximately 20 ​min. The enriching multiples of measured cellular elements were approximately 2.3–4.2. At final follow-up, the average Cobb angle correction was 83% (range, 61–96%). There was no obvious loss in correction with an average loss of 1.1° (2%). The visual analogue scale score and the Oswestry Disability Index score at final follow-up were significantly ameliorated than those preoperatively. The Scoliosis Research Society 30 questionnaire revealed remarkable improvement in the domains “pain”, “self-image/appearance”, and “satisfaction with management”. There was neither pseudarthrosis nor severe complication.

Conclusion

The use of SCR technology could be considered as an effective method for promoting spinal fusion in treating AIS. We proposed a safe, simple, and rapid approach to obtain effective bone grafts for spinal fusion.

The translational potential of this article

Enriched bone marrow obtained by selective cell retention technology has the potential to promote spinal fusion for the treatment of adolescent idiopathic scoliosis.

Bone regeneration in Ds-Red pig calvarial defect using allogenic transplantation of EGFP-pMSCs - A comparison of host cells and seeding cells in the scaffold

Background

Cells, scaffolds, and factors are the triad of regenerative engineering; however, it is difficult to distinguish whether cells in the regenerative construct are from the seeded cells or host cells via the host blood supply. We performed a novel in vivo study to transplant enhanced green fluorescent pig mesenchymal stem cells (EGFP-pMSCs) into calvarial defect of DsRed pigs. The cell distribution and proportion were distinguished by the different fluorescent colors through the whole regenerative period.

Method/Results

Eight adult domestic Ds-Red pigs were treated with five modalities: empty defects without scaffold (group 1); defects filled only with scaffold (group 2); defects filled with osteoinduction medium-loaded scaffold (group 3); defects filled with 5 x 10³ cells/scaffold (group 4); and defects filled with 5 x 10⁴ cells/scaffold (group 5). The in vitro cell distribution, morphology, osteogenic differentiation, and fluorescence images of groups 4 and 5 were analyzed. Two animals were sacrificed at 1, 2, 3, and 4 weeks after transplantation. The in vivo fluorescence imaging and quantification data showed that EGFP-pMSCs were represented in the scaffolds in groups 4 and 5 throughout the whole regenerative period. A higher seeded cell density resulted in more sustained seeded cells in bone regeneration compared to a lower seeded cell density. Host cells were recruited by seeded cells if enough space was available in the scaffold. Host cells in groups 1 to 3 did not change from the 1st week to 4th week, which indicates that the scaffold without seeded cells cannot recruit host cells even when enough space is available for cell ingrowth. The histological and immunohistochemical data showed that more cells were involved in osteogenesis in scaffolds with seeded cells.

Conclusion

Our in vivo results showed that more seeded cells recruit more host cells and that both cell types participate in osteogenesis. These results suggest that scaffolds without seeded cells may not be effective in bone transplantation.

Allograft Versus Demineralized Bone Matrix in Instrumented and Noninstrumented Lumbar Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

The aim was to determine the fusion efficacy of allograft and demineralized bone matrix (DBM) in lumbar instrumented and noninstrumented fusion procedures for degenerative lumbar disorders.

METHODS

A literature search was conducted using the PubMed and Cochrane databases. To be considered, publications had to meet 4 criteria: patients were treated for a degenerative lumbar disorder, a minimum group size of 10 patients, use of allograft or DBM, and at least a 2-year follow-up. Data on the study population, follow-up time, surgery type, grafting material, fusion rates, and its definition were collected.

RESULTS

The search yielded 692 citations with 17 studies meeting the criteria including 4 retrospective and 13 prospective studies. Six studies used DBM and 11 employed allograft alone or in the combination with autograft. For the allograft, fusion rates ranged from 58% to 68% for noninstrumented and from 68% to 98% for instrumented procedures. For DBM, fusion rates were 83% for noninstrumented and between 60% and 100% for instrumented lumbar fusion procedures.

CONCLUSIONS

Both allograft and DBM appeared to provide similar fusion rates in instrumented fusions. On the other hand, in noninstrumented procedures DBM was superior. However, a large variation in the type of surgery, outcomes collection, lack of control groups, and follow-up time prevented any significant conclusions. Thus, studies comparing the performance of allograft and DBM to adequate controls in large, well-defined patient populations and with a sufficient follow-up time are needed to establish the efficacy of these materials as adjuncts to fusion.

Adolescent idiopathic scoliosis correction by instrumented vertebral arthrodesis with autologous bone graft from local harvesting without bone substitute use: results with mean 3 year follow-up

PURPOSE

Bone substitutes' advantage is enhancing arthrodesis biologic support without further autologous bone graft harvested from other skeleton sites, as from posterior iliac crests; however, in our experience, bone substitutes' integration is often incomplete.

METHODS

From 2012 to 2017, we operated 108 patients by posterior instrumented vertebral arthrodesis in adolescent idiopathic scoliosis (AIS) correction, mean main curve 80° Cobb, and mean age 12 years and 6 months, with all pedicle screws instrumentation in main curve/curves area and hooks at upper tip of implant; bone graft has been harvested only at vertebral level, without bone substitutes or autologous graft from other patient sites or allogenic bone graft. We matched this group with 98 patients previously operated in which we used calcium triphosphate.

RESULTS

At 3 year mean follow-up, all patients in group treated with autologous bone graft only have complete and stable arthrodesis without loss of correction (mean curve 27° Cobb) or instrumentation failure. At 6 year mean follow-up in the group treated with autologous bone graft augmented by calcium triphosphate, 96 patients have stable arthrodesis without loss of correction (mean curve 24°), 1 case has implant break, and 1 case has 8° Cobb loss of correction.

CONCLUSION

Bone substitutes are a further cost in arthrodesis surgery and suboptimal integration leaves foreign bodies on vertebras. Our experience shows that all pedicle screw instrumentation and bracing after surgery obtain stable correction showing in time a solid arthrodesis with autologous bone only, harvested at local site, without bone substitutes or further bone graft.

Pseudarthrosis in adult and pediatric spinal deformity surgery: a systematic review of the literature and meta-analysis of incidence, characteristics, and risk factors

We conducted a systematic review with meta-analysis and qualitative synthesis. This study aims to characterize pseudarthrosis after long-segment fusion in spinal deformity by identifying incidence rates by etiology, risk factors for its development, and common features. Pseudarthrosis can be a painful and debilitating complication of spinal fusion that may require reoperation. It is poorly characterized in the setting of spinal deformity. The MEDLINE, EMBASE, and Cochrane databases were searched for clinical research including spinal deformity patients treated with long-segment fusions reporting pseudarthrosis as a complication. Meta-analysis was performed on etiologic subsets of the studies to calculate incidence rates for pseudarthrosis. Qualitative synthesis was performed to identify characteristics of and risk factors for pseudarthrosis. The review found 162 articles reporting outcomes for 16,938 patients which met inclusion criteria. In general, the included studies were of medium to low quality according to recommended reporting standards and study design. Meta-analysis calculated an incidence of 1.4% (95% CI 0.9-1.8%) for pseudarthrosis in adolescent idiopathic scoliosis, 2.2% (95% CI 1.3-3.2%) in neuromuscular scoliosis, and 6.3% (95% CI 4.3-8.2%) in adult spinal deformity. Risk factors for pseudarthrosis include age over 55, construct length greater than 12 segments, smoking, thoracolumbar kyphosis greater than 20°, and fusion to the sacrum. Choice of graft material, pre-operative coronal alignment, post-operative analgesics, and sex have no significant impact on fusion rates. Older patients with greater deformity requiring more extensive instrumentation are at higher risk for pseudarthrosis. Overall incidence of pseudarthrosis requiring reoperation is low in adult populations and very low in adolescent populations.

Orthobiologics in Pediatric Orthopedics

Orthobiologics are biologic devices or products used in orthopedic surgery to augment or enhance bone formation. The use of orthobiologics in pediatric orthopedics is less frequent than in other orthopedic subspecialties, mainly due to the naturally abundant healing potential and bone formation in children compared with adults. However, orthobiologics are used in certain situations in pediatric orthopedics, particularly in spine and foot surgery. Other uses have been reported in conjunction with specific procedures involving the tibia and pelvis. The use of bioabsorable implants to stabilize children's fractures is an emerging concept but has limited supporting data.

Structural Allograft versus Autograft for Instrumented Atlantoaxial Fusions in Pediatric Patients: Radiologic and Clinical Outcomes in Series of 32 Patients

BACKGROUND

Allograft with wire techniques showed a low fusion rate in pediatric atlantoaxial fusions (AAFs) in early studies. Using allograft in pediatric AAFs with screw/rod constructs has not been reported. Thus we compared the fusion rate and clinical outcomes in pediatric patients who underwent AAFs with screw/rod constructs using either a structural autograft or allograft.

METHODS

Pediatric patients (aged ≤12 years) who underwent AAFs between 2007 and 2015 were retrospectively evaluated. Patients were divided into 2 groups (allograft or autograft). Clinical and radiographic results were collected from hospital records and compared.

RESULTS

A total of 32 patients were included (18 allograft, 14 autograft). There were no significant group differences in age, sex, weight, diagnosis, or duration of follow-up. A similar fusion rate was achieved (allograft: 94%, 17/18; autograft: 100%, 14/14); however, the average fusion time was 3 months longer in the allograft group. Blood loss was significantly lower in the allograft group (68 ± 8.5 mL) than the autograft group (116 ± 12.5 mL). Operating time and length of hospitalization were slightly (nonsignificantly) shorter for the allograft group. A significantly higher overall incidence of surgery-related complications was seen in the autograft group, including a 16.7% (2/14) rate of donor-site-related complications.

CONCLUSIONS

The use of allograft for AAF was safe and efficacious when combined with rigid screw/rod constructs in pediatric patients, with a similar fusion rate to autografts and an acceptable complication rate. Furthermore, blood loss was less when using allograft and donor-site morbidity was eliminated; however, the fusion time was increased.

Allograft Bone Use in Pediatric Subaxial Cervical Spine Fusions

BACKGROUND

The use of freeze-dried allograft as a bone graft substitute for pediatric spine surgery is safe and efficacious in the thoracic and lumbar spines. Allograft bone use in segmental instrumented fusions in the subaxial cervical spine has not been well reported in the literature. We sought to describe our experience with allograft bone in this patient cohort, and to compare union rates to patients treated with autograft.

METHODS

Medical records were queried over a 10-year time period (2004 to 2014). Inclusion criteria were all pediatric patients (18 y old and below) who underwent subaxial cervical spine fusion with minimum follow-up of 24 months. Variables queried included demographics, type of graft material used, diagnosis, approach (anterior, posterior, combined), levels instrumented, placement of postoperative halo, surgical-related complications, and achievement of fusion.

RESULTS

A total of 26 patients qualified for inclusion (18 allograft, 8 autograft). No differences existed between the 2 groups regarding age, sex, or number of fused levels. In the allograft cohort, average age at initial surgery was 13.3 years (range, 5 to 18 y). The most common reasons for surgery included trauma (6), tumor (3), and syndrome-associated kyphosis (3). The average number of instrumented levels was 4 (range, 2 to 13). Four patients (22%) developed a postoperative surgical complication. There were 2 asymptomatic pseudarthroses not requiring revision. At a minimum of 24-month follow-up (average, 45 mo; range, 24 to 121 mo), the allograft group demonstrated a fusion rate of 88%, which was comparable with a fusion rate of 87% in the autograft group.

CONCLUSIONS

The use of allograft bone for pediatric subaxial instrumented cervical spine fusions is safe in a variety of conditions, with the same rate of fusion as autograft. Rates of complications are acceptable. To avoid donor-site morbidity from autogenous graft harvest, we recommend considering allograft bone in subaxial cervical spine fusions with modern segmental instrumentation.

LEVEL OF EVIDENCE

Level IV-case series; therapeutic.

National Trends in the Surgical Management of Adolescent Idiopathic Scoliosis: Analysis of a National Estimate of 60,108 Children From the National Inpatient Sample Over a 13-Year Time Period in the United States

STUDY DESIGN

Analysis of Nationwide Inpatient Sample (NIS).

OBJECTIVE

Evaluate evolution of operative treatment of adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Spinal surgery is one of the most rapidly evolving branches of surgery. Changes in AIS operations are incompletely defined.

METHODS

Children (10-18 years) with ICD-9 diagnosis of idiopathic scoliosis who underwent thoracic and/or lumbar spinal fusion identified in the NIS (1998-2011) were analyzed. Population-based utilization rates were calculated from US Census data. Patient demographics, surgical approach, operative techniques, complications during hospitalization, hospital stay length, and charges were analyzed.

RESULTS

60,108 children (46,256 girls, 13,776 boys, 76 gender not specified; average age 14.1 years) were identified. Thoracic fusions were the majority. Number of operations increased over time. For thoracic fusions, posterior operations significantly increased, whereas anterior and anterior/posterior operations decreased significantly. Although anterior operations for lumbar fusions declined, this was not as steep as thoracic. Use of autogenous bone graft (including iliac crest) significantly increased, which mirrored significant decreases in alternative fusion agents. Thoracoplasty significantly decreased, whereas osteotomy significantly increased. The average complication rate was 3.7%. Rates of blood transfusions, infection, and neural injury did not differ significantly from 1998 to 2011. Device-related complications increased significantly over time. Average lengths of hospital stay decreased significantly, whereas average total hospital charges increased significantly.

CONCLUSIONS

In a representative sample of the US population from 1998 to 2011, operative approaches and techniques for AIS significantly changed. Anterior procedure is rarely performed for thoracic curves; lumbar curves continue to be treated with anterior and posterior approaches. Osteotomy and autogenous bone graft increased, while thoracoplasty decreased. Overall complication rates remain stable, whereas hospital lengths of stays decreased and charges increased.

Type of bone graft or substitute does not affect outcome of spine fusion with instrumentation for adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

To compare clinical outcomes after spine instrumentation and fusion using 3 different bone grafts in children with adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Autogenous iliac crest bone graft (AIC) is the "gold standard" to promote fusion in posterior AIS operations, although the morbidity of harvest is a concern. There is limited data comparing outcomes after AIS surgery based on types of bone grafts.

METHODS

Children (10-18 yr) with AIS who underwent deformity correction via a posterior approach were identified in the Spinal Deformity Study Group database. All had a minimum of 2-year follow-up. Patients were subdivided into 3 groups based on bone graft used: AIC, allograft, and bone substitute (BS). Clinical data included patient demographics, operative details, postoperative analgesic use, and perioperative complications. Lenke curve type and curve magnitude changes were radiographically analyzed. The Scoliosis Research Society-30 questionnaire was used to assess clinical outcomes.

RESULTS

461 patients met inclusion criteria (girls: 381, boys: 80; average age 14.7 ± 1.7) and consisted of 152 AIC patients (124 girls, 28 boys), 199 allograft patients (167 girls, 32 boys), and 110 BS patients (90 girls, 20 boys). There was no difference in age (P = 0.41) or gender (P = 0.82). The BS group had significantly smaller preoperative curves and shorter operative times. Postoperatively, patients who received BS had significantly longer hospital stays, used higher quantities of patient-controlled intravenous analgesia and used epidurals longer. The AIC group used patient-controlled intravenous analgesia significantly longer. There were no differences between the groups in regards to curve type, number of levels fused, postoperative infections, pseudarthrosis, reoperations for any indication, and Scoliosis Research Society-30 scores at the latest follow-up.

CONCLUSION

Outcomes after primary posterior spinal fusion with instrumentation are not influenced by type of bone graft or substitute.

LEVEL OF EVIDENCE

3.

Treatment for severe idiopathic upper thoracic scoliosis in adolescence

STUDY DESIGN

To review the study of severe upper thoracic scoliosis (>90 degrees) in adolescence treated with pedicle screw constructs.

OBJECTIVE

The purpose of the present study was to analyze the treatment for upper thoracic scoliosis in adolescence.

SUMMARY OF BACKGROUND DATA

Upper thoracic scoliosis is an uncommon spinal deformity in young children. Upper thoracic scoliosis is special.

METHODS

There were 21 patients (11 boys and 10 girls) with severe upper thoracic scoliosis and their mean age was 15 years (range, 13-18 y). The mean Cobb angle was 102.2 degrees (90-118 degrees) The clavicle angle ranged from 18 to 23 degrees, with an average of 21 degrees. Patients with the major curve of scoliosis located in the upper thoracic spine were treated with a posterior spinal fusion with a pedicle screw-only construct. There was a minimum 2-year follow-up. Follow-up information was obtained clinically and radiologically.

RESULTS

All patients underwent a posterior spinal fusion with a pedicle screw-only construct. Their shoulders were nearly balanced. The preoperative major curve was 102.2±8.9 degrees with a flexibility of 25.8%±8.1% in a side-bending film. The deformity was corrected to 29.7±5.9 and 32.1±5.6 degrees at the most recent follow-up. There was a 3.9-degree correction loss during the postoperative follow-up. There were no neurological or vascular complications at 2 years of follow-up. There was no crankshaft phenomenon.

CONCLUSIONS

The pedicle screw constructs can be safely used for severe upper thoracic scoliosis. Curve correction is powerful for these curves, which are stiff and difficult to manage. Screw accuracy was excellent in this review.

Radiographic and patient-based outcome analysis of different bone-grafting techniques in the surgical treatment of idiopathic scoliosis with a minimum 4-year follow-up: allograft versus autograft/allograft combination

BACKGROUND CONTEXT

Autograft and allograft have been equally successful in achieving arthrodesis, but whether there is any difference in their effect on patient outcome, especially early, has not been determined.

PURPOSE

To determine if autograft in addition to allograft is associated with decreased healing period pain, increased early function, or both.

STUDY DESIGN

This is a retrospective comparative case series.

PATIENT SAMPLE

A sample of 47 patients, 20 years or younger with adolescent idiopathic scoliosis treated by the same surgeon at the same institution using third-generation segmental spinal instrumentation and arthrodesis.

OUTCOME MEASURE

Function and pain were quantified at periodic intervals using the Scoliosis Research Society (SRS) health-related quality of life (HRQoL) questionnaire. Clinical and radiographic follow-ups were completed.

METHODS

Freeze-dried corticocancellous allograft (AL) was used in 26 patients and allograft plus iliac crest autograft (AL-AU) in 21 patients. Radiographs and outcome measures, including SRS-24 or SRS-22 HRQoL questionnaires, were obtained preoperatively and at intervals with a 4-year follow-up available for 92% (25/26) of AL patients and 90% (19/21) of AL-AU patients.

RESULTS

There were no differences between the AL and AL-AU groups' ages, curve patterns, and complications. Neither group had a major complication or pseudoarthrosis. There were no main curve size differences at any interval. Pain scores were similar at all intervals: AL/AL-AU preoperative, 4.1/4.0; early follow-up (<1 year), 3.7/4.1; midterm follow-up (1-2 years), 4.4/4.6; and late follow-up (>3 years), 4.1/4.0. Function scores were also similar at all intervals: AL/AL-AU preoperative, 4.7/4.6; early follow-up, 4.2/4.3; midterm follow-up, 4.9/4.9; and late follow-up, 4.5/4.4.

CONCLUSIONS

The addition of autograft to allograft did not result in decreased pain or increased function at any time interval up to 4 years. We conclude that the addition of iliac crest autograft does not result in any advantage over freeze-dried allograft alone in the treatment of adolescent idiopathic scoliosis.

A systematic review of comparative studies on bone graft alternatives for common spine fusion procedures

BACKGROUND

The increased prevalence of spinal fusion surgery has created an industry focus on bone graft alternatives. While autologous bone graft remains the gold standard, the complications and morbidity from harvesting autologous bone drives the search for reliable and safe bone graft substitutes. With the recent information about the adverse events related to bone morhogenetic protein use, it is appropriate to review the literature about the numerous products that are not solely bone morphogenetic protein.

PURPOSE

The purpose of this literature review is to determine the recommendations for use of non-bone morphogenetic protein bone graft alternatives in the most common spine procedures based on a quantifiable grading system.

STUDY DESIGN

Systematic literature review.

METHODS

A literature search of MEDLINE (1946-2012), CINAHL (1937-2012), and the Cochrane Central Register of Controlled Trials (1940-April 2012) was performed, and this was supplemented by a hand search. The studies were then evaluated based on the Guyatt criteria for quality of the research to determine the strength of the recommendation.

RESULTS

In this review, more than one hundred various studies on the ability of bone graft substitutes to create solid fusions and good patient outcomes are detailed.

CONCLUSION

The recommendations for use of bone graft substitutes and bone graft extenders are based on the strength of the studies and given a grade.

Silicate-substituted calcium phosphate as a bone graft substitute in surgery for adolescent idiopathic scoliosis

STUDY DESIGN AND OBJECTIVE

The purpose of this prospective clinical study is to evaluate the clinical and radiographic outcomes using a silicate-substituted calcium phosphate (Si-CaP) as a bone graft substitute in surgery for adolescent idiopathic scoliosis (AIS). In posterior corrective surgery for AIS, harvesting autologous bone from the iliac crest still represents the gold standard to augment the local bone graft though it is comparatively invasive and associated with donor site morbidity. Si-CaP enriched with bone marrow aspirate (BMA) might be an appropriate bone graft extender to overcome these difficulties.

METHODS

Eighteen female and three male patients with AIS who underwent corrective posterior instrumentation were observed clinically and radiographically for a minimum of 24 months. In all cases, 20-40 ml Si-CaP granules (ACTIFUSE) mixed with BMA from vertebral bodies was used to extend the local bone graft. Fusion was assessed by standardized conventional radiographs regarding loss of correction and implant failure. Clinical outcome was evaluated with use of the Scoliosis Research Society-22 patient Questionnaire (SRS-22) and a Visual Analog Scale (VAS) for back pain.

RESULTS

Cobb angle of major curves averaged 63° preoperatively, 22° after surgery, and 24° at final follow-up, with a maximum loss of correction of 7° recorded after 4 months. No adverse effects related to the study material had been observed. In all patients, there was no evidence of implant failure, and formation of an increasingly densifying 'fusion mass' was visible, as assessed by conventional radiography. VAS score for back pain averaged 1.7 before surgery, 2.3 at discharge, and 1.5 at final follow-up. Outcome assessment using the SRS-22 revealed a significantly enhanced overall health-related quality of life (84 vs. 74 % before surgery; P = 0.0005) due to a significant improvement of the domains 'self image' (77 vs. 59 %; P = 0.0002) and 'pain' (88 vs. 80 %; P = 0.02). Patients' management satisfaction averaged 93 %.

CONCLUSIONS

Si-CaP augmented with BMA from vertebral bodies seems to prove an effective, safe, and easy to handle bone graft extender in scoliosis surgery and thus a suitable alternative to bone harvesting procedures.

A survey of current controversies in scoliosis surgery in the United Kingdom

STUDY DESIGN

A 10-point questionnaire was constructed to identify the philosophy of surgeons on various aspects of scoliosis surgery, such as choice of implant, bone graft, autologous blood transfusion, cord monitoring, and computer-assisted surgery. Comparisons were then made with recommendations published in the spinal literature.

OBJECTIVE

To determine certain aspects of the current practice of scoliosis surgery in the United Kingdom.

SUMMARY OF BACKGROUND DATA

Guidelines for good clinical practice in spinal deformity surgery are available in the United Kingdom but do not cover a number of controversial issues.

METHODS

Consultants and fellows attended the 2009 British Scoliosis Society meeting. Fifty questionnaires were completed by 45 consultants and 5 fellows.

RESULTS

All pedicle screw constructs favored by 25 of 50, hybrid 24 of 50 (1 undecided). Posterior construct of fewer than 10 levels, 20 of 50 would not cross-link, 11 of 50 used 1, and 19 of 20 used 2 or more. More than 10 levels 17 of 50 considered cross-links unnecessary, 4 of 50 used 1 and 29 of 50 used 2 or more. Eighty-eight percent preferred titanium alloy implants, whereas others used a mixture of stainless steel and cobalt chrome. When using bone graft, respondents used bone substitutes (24), iliac crest graft (14), allograft (12) and demineralized bone matrix (9) in addition to local bone. Ten of 50 would use recombinant bone morphogenetic protein (3 for revision cases only). Thirty-nine of 50 routinely used intraoperative cell salvage and 4 of 50 never used autologous blood. All used cord monitoring: sensory (19 of 50), motor (2 of 50), and combined (29 of 50). None used computer-aided surgery. Twenty-six operated alone, 12 operated in pairs, and 12 varied depending on type of case.

CONCLUSION

This survey shows interesting variations in scoliosis surgery in the United Kingdom. It may reflect the conflicting evidence in the literature.

Deep wound infection following pediatric scoliosis surgery: incidence and analysis of risk factors

BACKGROUND

Deep wound infection after spinal surgery is a severe complication that often requires prolonged medical and surgical management. It can compromise the outcome of the deformity correction, especially in patients requiring surgical intervention with subsequent removal of implants. Ascertaining the incidence and risk factors leading to infection may help to prevent this problem.

METHODS

We reviewed the hospital charts of all patients who underwent spinal deformity correction from 1996 to 2005.

RESULTS

In all, 227 patients were identified (139 idiopathic, 57 neuromuscular, 8 syndromic, 6 congenital, 17 other); 191 patients were treated with posterior instrumentation and fusion, 11 with anterior-only procedures and 24 with combined anterior and posterior procedures. Final follow-up ranged from 1 to 9.5 years. Infection developed in 14 patients. The overall incidence of infection was 6.2%. Drainage and back pain were the most common presenting symptoms. The incidence of infection was higher among patients with nonidiopathic diagnoses (risk ratio [RR] 8.65, p < 0.001). Use of allograft bone was associated with a higher rate of infection (RR 9.66, p < 0.001) even when stratified by diagnosis (nonidiopathic diagnoses, RR 7.6, p = 0.012). Higher volume of instrumentation was also a risk factor for infection (p = 0.022). Coagulase-negative Staphyloccocus was the most commonly identified organism, followed by Propionibacterium acnes and Pseudomonas.

CONCLUSION

Development of infection following scoliosis surgery was found to be associated with several risk factors, including a nonidiopathic diagnosis, the use of allograft and a higher volume of instrumentation. Preventative measures addressing these factors may decrease the rate of infection.

Bone grafting options for lumbar spine surgery: a review examining clinical efficacy and complications

Background

Iliac crest harvest has been considered the “gold standard” at producing successful arthrodesis of the lumbar spine but is also associated with many donor-site morbidities. Many alternatives have been used to avoid iliac crest harvest, including autologous bone from other donor sites, allogeneic bone, ceramics, and recombinant human bone morphogenetic proteins (rhBMPs). This review will highlight the properties and preparations of these graft types and their potential complications and reported clinical efficacy.

Methods

A Medline search was conducted via PubMed by use of the following terms in various combinations: lumbar fusion, freeze-dried allograft, fresh-frozen allograft, autograft, iliac crest, demineralized bone matrix, rhBMP-2, rhBMP-7, scoliosis, bone marrow aspirate, HEALOS, coralline hydroxyapatite, beta tricalcium phosphate, synthetic, ceramics, spinal fusion, PLF, PLIF, ALIF, and TLIF. Only articles written in English were assessed for appropriate material. Related articles were also assessed depending on the content of articles found in the original literature search.

Conclusions

Although iliac crest remains the gold standard, reported success with alternative approaches, especially in combination, has shown promise. Stronger evidence with limited sources of potential bias is necessary to provide a clear picture of their clinical efficacy.

Clinical and radiographic outcomes of the treatment of adolescent idiopathic scoliosis with segmental pedicle screws and combined local autograft and allograft bone for spinal fusion: a retrospective case series

Background

High morbidity has been reported with iliac crest bone graft harvesting; however, donor bone is typically necessary for posterior spinal fusion. Autograft bone combined with allograft may reduce the morbidity associated with iliac crest bone harvesting and improve the fusion rate. Our aim in this study was to determine the presence of complications, pseudarthrosis, non-union, and infection using combined in situ local autograft bone and freeze-dried cancellous allograft bone in patients undergoing posterior spinal fusion for the treatment of adolescent idiopathic scoliosis.

Methods

A combination of in situ local autograft bone and freeze-dried cancellous allograft blocks were used in 50 consecutive patients with adolescent idiopathic scoliosis treated by posterior fusion and Moss Miami pedicle screw instrumentation. Results were assessed clinically and radiographically and quality of life and functional outcome was evaluated by administration of a Chinese version of the SRS-22 survey.

Results

There were 41 female and 9 male patients included for analysis with an average age of 14.7 years (range, 12-17). All patients had a minimum follow-up of 18 months (range, 18 to 40 months). The average preoperative Cobb angle was 49.8° (range, 40° to 86°). The average number of levels fused was 9.8 (range, 6-15). Patients had a minimum postoperative follow-up of 18 months. At final follow-up, the average Cobb angle correction was 77.8% (range, 43.4 to 92.5%). There was no obvious loss in the correction, and the average loss of correction was 1.1° (range, 0° to 4°). There was no pseudarthrosis and no major complications.

Conclusions

In situ autograft bone combined with allograft bone may be a promising method enhances spinal fusion in AIS treated with pedicle screw placement. By eliminating the need for iliac crest bone harvesting, significant morbidity may be avoided.

[Bone substitutes in scoliosis surgery]

In spinal fusion procedures, the local bone that is resected serves as the base bone graft for attaining biological fusion. The local bone is frequently not sufficient and requires supplementary grafting. Autologous bone transplantation is still regarded as the gold standard but might cause additional complications; also, autograft resources are limited. Alternatively, allografts and a wide variety of different bone substitutes are available.The bone substitutes currently used in scoliosis surgery are presented, and their clinical significance is elucidated by a review of the literature. Furthermore, our own experiences and clinical practice are compared with those in the literature and are critically discussed. The recently growing number of scientific publications reporting on bone substitutes reflects the immense interest and relevance of this issue. In scoliosis surgery, calcium phosphate ceramics together with bone marrow aspirate are increasingly applied.Although harvesting of autologous bone continues to be the accepted standard to extend the local autograft in scoliosis surgery, there is a clear trend toward the use of bone substitutes.

Antibiotic-loaded allograft decreases the rate of acute deep wound infection after spinal fusion in cerebral palsy

STUDY DESIGN

A retrospective matched cohort study with control group.

OBJECTIVE

To compare the infection rate after posterior spinal fusion with unit rod instrumentation with or without gentamicin-impregnated allograft bone in children with cerebral palsy (CP).

SUMMARY OF BACKGROUND DATA

Previous studies evaluating wound infection rates after spinal fusion surgery in children with CP report an 8.7% to 10% wound infection rate. The concept of using antibiotic-loaded bone graft (AbBGF) to provide local antibiotics has been explored in high risk patients, such as those with osteomyelitis or infected joint arthroplasty. There have been no reports of using AbBGF prophylactically in spine surgery.

METHODS

After IRB approval, the medical records of 220 children with CP who underwent spinal fusion with unit rod instrumentation for a primary spinal deformity between January 2000 through December 2006 at a single institution were retrospectively reviewed. We evaluated the incidence of postoperative wound infection in patients with AbBGF and those without bone graft (BGF).

RESULTS

One hundred fifty-four patients received AbBGF during spinal fusion surgery and 6 patients (3.9%) developed a deep wound infection. Ten (15.2%) of the 66 patients without AbBGF developed a deep wound infection. The difference between groups was statistically different (P = 0.003). The mean age at surgery, preoperative Cobb angle, correction rate, operative time, and estimated blood loss were not statistically different between the 2 groups (P > 0.05). The length of hospital stay was decreased in the AbBGF group (P < 0.05).

CONCLUSION

The incidence of deep wound infection after spinal fusion in 220 children with CP scoliosis decreased from 15% to 4% with the use of prophylactic antibiotics in the corticocancellous allograft bone.

Surgical revision rates of hooks versus hybrid versus screws versus combined anteroposterior spinal fusion for adolescent idiopathic scoliosis

STUDY DESIGN

Multi-institution retrospective review.

OBJECTIVE

To determine the surgical revision rates of hook, hybrid, anteroposterior, and total pedicle screw constructs for adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Much debate continues on the safety, efficacy, and cost of thoracic pedicle screws. Nonetheless, there are no large series that have evaluated the revision rate of various constructs in AIS to determine the need for repeat surgery, and therefore, the added indirect costs and risks of additional procedures.

METHODS

We retrospectively reviewed the surgical case logs of 1428 patients with AIS at 2 institutions from 1990 to 2004, and the clinical records and radiographs of revision cases. Patients were classified into 1 of 4 groups: hook, hybrid hook and screw, all pedicle screw, and combined anteroposterior fusion constructs. Overall, there were 65 (4.6%) returns to the operating room, or 55 (3.9%) cases after excluding infections without concomitant pseudarthrosis.

RESULTS

Of the 65 revision cases, there were 52 females and 13 males, at an average age at first surgery of 13.9 years (range, 9-18 years), and an average age at revision of 14.7 years (range, 12-23 years). For the revision cases, the average initial Cobb was 61.9 degrees (range 44 degrees -110 degrees ), and this was not statistically different within the cohorts (P > 0.05). In terms of revision rate, all hook constructs had a higher revision rate secondary to instrumentation failure when compared with screws, while both hook and hybrid constructs had an overall higher surgical revision rate when compared with screw constructs or anteroposterior constructs (all P <or= 0.05). The pseudarthrosis rate trended toward, but did not meet, statistical significance between these same groups.

CONCLUSION

All pedicle screw and anteroposterior constructs have a lower surgical revision rate when compared with hook and hybrid constructs. The hidden patient and financial costs of these findings should be considered when evaluating overall instrumentation efficacy.

The use of irradiated allograft in a paediatric population: an Indian experience

Lyophilised, irradiated bone allografts available for the first time in the country from the Tata Memorial Hospital Tissue Bank were used in 30 paediatric patients from January 2001 to August 2004. They included 20 patients of scoliosis of various origin and ten with assorted orthopaedic conditions including one congenital kyphosis, two Pott's spine, one Perthes disease, one developmental dysplasia of the hip (DDH), one infective non-union, one fibrous dysplasia and three with bone defects either due to trauma, a cyst or removal of hardware. Morsellised allograft was used in 28 patients. In those cases of scoliosis in which ribs were resected out during costectomy, the morsellised allograft was mixed with morsellised rib autograft. Non-morsellised femoral head grafts were used in two patients, one a case of varus open derotation osteotomy in Perthes disease and the other an acetabuloplasty in DDH. Patients were followed at intervals of 8-12 weeks and radiological evaluation was done periodically. The follow up period ranged from 1 to 4 years post surgery. All patients with scoliosis showed excellent union at the grafting site with non-progression of curve and no signs of loosening at implant site. The two patients, in whom non-morsellised femoral head grafts were used, both showed incorporation of the graft with good fusion within a 4 month period. None of the patient had infection, non-union, pseudoarthrosis, fracture at the graft site, or any other complication.

Morbidity of iliac crest bone graft harvesting in adolescent deformity surgery

The iliac crest as a source of bone graft has remained popular and continues to be the standard source of bone graft material in spinal arthrodesis surgery. The purpose of the present study was to quantify the frequency and severity of posterior iliac crest bone graft harvest site pain associated with adolescent spinal deformity correction procedures. Patients were evaluated prospectively at a minimum of 1 year after a spinal fusion procedure for idiopathic scoliosis or kyphosis. Patients were asked to quantify the pain level at their harvest site over the previous month based on a 0-to-10 numeric rating scale. Data were collected on 71 patients: 60 with adolescent idiopathic scoliosis and 11 with Scheuermann's kyphosis. There was no gender difference noted, with 1 of the 10 boys (10%) and 6 of the 61 girls (10%) reporting postoperative pain. Seven of 60 patients with scoliosis reported pain (12%), whereas none of the patients with Scheuermann's kyphosis reported pain. None reported a pain level greater than 3 of 10 or any effect on activity level. This series shows that iliac crest bone graft harvest site pain is absent in most patients (90%) and of limited severity in those who reported pain (score <or=3), suggesting that the postoperative morbidity associated with autograft use is minimal in adolescent patients.