The Evidence for the Use of Osteobiologics in Hybrid Constructs (Anterior Cervical Discectomy and Fusion and Total Disc Replacement) in Multilevel Cervical Degenerative Disc Disease: A Systematic Review.

STUDY DESIGN: Systematic review. OBJECTIVE: Examine the clinical evidence for the use of osteobiologics in hybrid surgery (combined anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR)) in patients with multilevel cervical degenerative disc disease (DDD). METHODS: PubMed and Embase were searched between January 2000 and August 2020. Clinical studies investigating 18-80 year old patients with multilevel cervical DDD who underwent hybrid surgery with or without the use of osteobiologics were considered eligible. Two reviewers independently screened and assessed the identified articles. The methodological index for non-randomized studies (MINORS) tool and the risk of bias (RoB 2.0) assessment tool were used to assess risk of bias. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) was used to evaluate quality of evidence across studies per outcome. RESULTS: Eleven studies were included. A decrease in cervical range of motion was observed in most studies for both the hybrid surgery and the control groups consisting of stand-alone ACDF or TDR. Fusion rates of 70-100% were reported in both the hybrid surgery and control groups consisting of stand-alone ACDF. The hybrid surgery group performed better or comparable to the control group in terms of adjacent segment degeneration. Studies reported an improvement in visual analogue scale for pain and neck disability index values after surgery compared to preoperative scores for both treatment groups. The included studies had moderate methodological quality. CONCLUSIONS: There is insufficient evidence for assessing the use of osteobiologics in multilevel hybrid surgery and additional high quality and controlled research is deemed essential.

AO Spine Guideline for the Use of Osteobiologics (AOGO) in Anterior Cervical Discectomy and Fusion for Spinal Degenerative Cases.

STUDY DESIGN: Guideline. OBJECTIVES: To develop an international guideline (AOGO) about the use of osteobiologics in anterior cervical discectomy and fusion (ACDF) for treating degenerative spine conditions. METHODS: The guideline development process was guided by AO Spine Knowledge Forum Degenerative (KF Degen) and followed the Guideline International Network McMaster Guideline Development Checklist. The process involved 73 participants with expertise in degenerative spine diseases and surgery from 22 countries. Fifteen systematic reviews were conducted addressing respective key topics and evidence was collected. The methodologist compiled the evidence into GRADE Evidence-to-Decision frameworks. Guideline panel members judged the outcomes and other criteria and made the final recommendations through consensus. RESULTS: Five conditional recommendations were created. A conditional recommendation is about the use of allograft, autograft or a cage with an osteobiologic in primary ACDF surgery. Other conditional recommendations are about the use of osteobiologic for single- or multi-level ACDF, and for hybrid construct surgery. It is suggested that surgeons use other osteobiologics rather than human bone morphogenetic protein-2 (BMP-2) in common clinical situations. Surgeons are recommended to choose 1 graft over another or 1 osteobiologic over another primarily based on clinical situation, and the costs and availability of the materials. CONCLUSION: This AOGO guideline is the first to provide recommendations for the use of osteobiologics in ACDF. Despite the comprehensive searches for evidence, there were few studies completed with small sample sizes and primarily as case series with inherent risks of bias. Therefore, high-quality clinical evidence is demanded to improve the guideline.

Clinical outcomes and complications of S53P4 bioactive glass in chronic osteomyelitis and septic non-unions: a retrospective single-center study.

INTRODUCTION: Dead space management following debridement surgery in chronic osteomyelitis or septic non-unions is one of the most crucial and discussed steps for the success of the surgical treatment of these conditions. In this retrospective clinical study, we described the efficacy and safety profile of surgical debridement and local application of S53P4 bioactive glass (S53P4 BAG) in the treatment of bone infections. METHODS: A consecutive single-center series of 38 patients with chronic osteomyelitis (24) and septic non-unions (14), treated with bioactive glass S53P4 as dead space management following surgical debridement between May 2015 and November 2020, were identified and evaluated retrospectively. RESULTS: Infection eradication was reached in 22 out of 24 patients (91.7%) with chronic osteomyelitis. Eleven out of 14 patients (78.6%) with septic non-union achieved both fracture healing and infection healing in 9.1 ± 4.9 months. Three patients (7.9%) developed prolonged serous discharge with wound dehiscence but healed within 2 months with no further surgical intervention. Average patient follow-up time was 19.8 months ± 7.6 months. CONCLUSION: S53P4 bioactive glass is an effective and safe therapeutic option in the treatment of chronic osteomyelitis and septic non-unions because of its unique antibacterial properties, but also for its ability to generate a growth response in the remaining healthy bone at the bone-glass interface.

Biomechanical evaluation of different semi-rigid junctional fixation techniques using finite element analysis.

BACKGROUND: Proximal junctional failure is a common complication attributed to the rigidity of long pedicle screw fixation constructs used for surgical correction of adult spinal deformity. Semi-rigid junctional fixation achieves a gradual transition in range of motion at the ends of spinal instrumentation, which could lead to reduced junctional stresses, and ultimately reduce the incidence of proximal junctional failure. This study investigates the biomechanical effect of different semi-rigid junctional fixation techniques in a T8-L3 finite element spine segment model. METHODS: First, degeneration of the intervertebral disc was successfully implemented by altering the height. Second, transverse process hooks, one- and two-level clamped tapes, and one- and two-level knotted tapes instrumented proximally to three-level pedicle screw fixation were validated against ex vivo range of motion data of a previous study. Finally, the posterior ligament complex forces and nucleus pulposus stresses were quantified. FINDINGS: Simulated range of motions demonstrated the fidelity of the general model and modelling of semi-rigid junctional fixation techniques. All semi-rigid junctional fixation techniques reduced the posterior ligament complex forces at the junctional zone compared to pedicle screw fixation. Transverse process hooks and knotted tapes reduced nucleus pulposus stresses, whereas clamped tapes increased nucleus pulposus stresses at the junctional zone. INTERPRETATION: The relationship between the range of motion transition and the reductions in posterior ligament complex and nucleus pulposus stresses was complex and dependent on the fixation techniques. Clinical trials are required to compare the effectiveness of semi-rigid junctional fixation techniques in terms of reducing proximal junctional failure incidence rates.

Biomechanical Evaluation of Semi-rigid Junctional Fixation Using a Novel Cable Anchor System to Prevent Proximal Junctional Failure in Adult Spinal Deformity Surgery.

STUDY DESIGN: A porcine cadaveric biomechanical study. OBJECTIVE: To biomechanically evaluate a novel Cable Anchor System as semi-rigid junctional fixation technique for the prevention of proximal junctional failure after adult spinal deformity surgery and to make a comparison to alternative promising prophylactic techniques. SUMMARY OF BACKGROUND DATA: The abrupt change of stiffness at the proximal end of a pedicle screw construct is a major risk factor for the development of proximal junctional failure after adult spinal deformity surgery. A number of techniques that aim to provide a gradual transition zone in range of motion (ROM) at the proximal junction have previously been studied. In this study, the design of a novel Cable Anchor System, which comprises a polyethylene cable for rod fixation, is assessed. METHODS: Ten T6-T13 porcine spine segments were subjected to cyclic 4 Nm pure-moment loading. The following conditions were tested: uninstrumented, 3 level pedicle screw fixation (PSF), and PSF with supplementary Cable Anchors applied proximally at 1-level (Anchor1) or 2-levels (Anchor2), transverse process hooks (TPH), and 2-level sublaminar tapes (Tape2). The normalized segmental range of motion in the junctional zone was compared using one-way analysis of variance and linear regression. RESULTS: Statistical comparison at the level proximal to PSF showed significantly lower ROMs for all techniques compared to PSF fixation alone in all movement directions. Linear regression demonstrated a higher linearity for Anchor1 (0.820) and Anchor2 (0.923) in the junctional zone in comparison to PSF (1-level: 0.529 and 2-level: 0.421). This linearity was similar to the compared techniques (TPH and Tape2). CONCLUSION: The Cable Anchor System presented in this study demonstrated a gradual ROM transition zone at the proximal end of a rigid pedicle screw construct similar to TPH and 2-level sublaminar tape semi-rigid junctional fixation constructs, while providing the benefit of preserving the posterior ligament complex.Level of Evidence: 5.

Peptide Enhanced Bone Graft Substitute Presents Improved Short-Term Increase in Bone Volume and Construct Stiffness Compared to Iliac Crest Autologous Bone in an Ovine Lumbar Interbody Fusion Model.

STUDY DESIGN: Preclinical ovine model. OBJECTIVE: To assess the in vivo efficacy and safety of the P-15 L bone graft substitute and compare its performance to autologous iliac crest bone graft (ICBG) for lumbar interbody fusion indications. METHODS: Thirty skeletally mature sheep underwent lumbar interbody fusion surgery. Half of the sheep received autologous ICBG and the other half the peptide enhanced bone graft substitute (P-15 L). Following termination at 1, 3, and 6 months after surgery, the operated segments were analyzed using micro computed tomography (µCT), histology, and destructive mechanical testing. Additional systemic health monitoring was performed for the P-15 L group. RESULTS: One month after surgery, there was only minor evidence of bone remodeling and residual graft material could be clearly observed within the cage. There was active bone remodeling between 1 and 3 months after surgery. At 3 months after surgery significantly denser and stiffer bone was found in the P-15 L group, whereas at 6 months, P-15 L and ICBG gave similar fusion results. The P-15 L bone graft substitute did not have any adverse effects on systemic health. CONCLUSIONS: The drug device combination P-15 L was demonstrated to be effective and save for lumbar interbody fusion as evidenced by this ovine model. Compared to autologous ICBG, P-15 L seems to expedite bone formation and remodeling but in the longer-term fusion results were similar.

Early bone ingrowth and segmental stability of a trussed titanium cage versus a polyether ether ketone cage in an ovine lumbar interbody fusion model.

BACKGROUND CONTEXT: Lumbar interbody fusion is an effective treatment for unstable spinal segments. However, the time needed to establish a solid bony interbody fusion between the two vertebrae may be longer than twelve months after surgery. During this time window, the instrumented spinal segment is assumed to be at increased risk for instability related complications such as cage migration or subsidence. It is hypothesized that the design of new interbody cages that enable direct osseointegration of the cage at the vertebral endplates, without requiring full bony fusion between the two vertebral endplates, might shorten the time window that the instrumented spinal segment is susceptible to failure. PURPOSE: To quantify the bone ingrowth and resulting segmental stability during consolidation of lumbar interbody fusion using two different cage types. STUDY DESIGN: Preclinical ovine model. METHODS: Seven skeletally mature sheep underwent bi-segmental lumbar interbody fusion surgery with one conventional polyether ether ketone (PEEK) cage, and one newly developed trussed titanium (TT) cage. After a postoperative time period of 13 weeks, non-destructive range of motion testing, and histologic analysis was performed. Additionally, sample specific finite element (FE) analysis was performed to predict the stability of the interbody fusion region alone. RESULTS: Physiological movement of complete spinal motion segments did not reveal significant differences between the segments operated with PEEK and TT cages. The onset of creeping substitution within the cage seemed to be sooner for PEEK cages, which led to significantly higher bone volume over total volume (BV/TV) compared with the TT cages. TT cages showed significantly more direct bone to implant contact (BIC). Although the mean stability of the interbody fusion region alone was not statistically different between the PEEK and TT cages, the variation within the cage types illustrated an all-or-nothing response for the PEEK cages while a more gradual increase in stability was found for the TT cages. CONCLUSIONS: Spinal segments operated with conventional PEEK cages were not different from those operated with newly developed TT cages in terms of segmental stability but did show a different mechanism of bone ingrowth and attachment. Based on the differences in development of bony fusion, we hypothesize that TT cages might facilitate increased early segmental stability by direct osseointegration of the cage at the vertebral endplates without requiring complete bony bridging through the cage. CLINICAL SIGNIFICANCE: Interbody cage type affects the consolidation process of spinal interbody fusion. Whether different consolidation processes of spinal interbody fusion result in clinically significant differences requires further investigation.

Local bone metabolism during the consolidation process of spinal interbody fusion.

INTRODUCTION: Although computed tomography (CT) can identify the presence of eventual bony bridges following lumbar interbody fusion (LIF) surgery, it does not provide information on the ongoing formation process of new bony structures. 18F sodium fluoride (18F-NaF) positron emission tomography (PET) could be used as complementary modality to add information on the bone metabolism at the fusion site. However, it remains unknown how bone metabolism in the operated segment changes early after surgery in uncompromised situations. This study aimed to quantify the changes in local bone metabolism during consolidation of LIF. MATERIALS AND METHODS: Six skeletally mature sheep underwent LIF surgery. 18F-NaF PET/CT scanning was performed 6 and 12 weeks postoperatively to quantify the bone volume and metabolism in the operated segment. Bone metabolism was expressed as a function of bone volume. RESULTS: Early in the fusion process, bone metabolism was increased at the endplates of the operated vertebrae. In a next phase, bone metabolism increased in the center of the interbody region, peaked, and declined to an equilibrium state. During the entire postoperative time period of 12 weeks, bone metabolism in the interbody region was higher than that of a reference site in the spinal column. CONCLUSION: Following LIF surgery, there is a rapid increase in bone metabolism at the vertebral endplates that develops towards the center of the interbody region. Knowing the local bone metabolism during uncompromised consolidation of spinal interbody fusion might enable identification of impaired bone formation early after LIF surgery using 18F-NaF PET/CT scanning.

Mid-term clinical results of chronic cavitary long bone osteomyelitis treatment using S53P4 bioactive glass: a multi-center study.

Introduction: Chronic osteomyelitis is a challenging condition in the orthopedic practice and traditionally treated using local and systemic antibiotics in a two-stage surgical procedure. With the introduction of the antimicrobial biomaterial S53P4 bioactive glass (Bonalive®), chronic osteomyelitis can be treated in a one-stage procedure. This study evaluated the mid-term clinical results of patients treated with S53P4 bioactive glass for long bone chronic osteomyelitis. Methods: In this prospective multi-center study, patients from two different university medical centers in the Netherlands were included. One-stage treatment consisted of debridement surgery, implantation of S53P4 bioactive glass, and treatment with culture-based systemic antibiotics. If required, wound closure by a plastic surgeon was performed. The primary outcome was the eradication of infection, and a secondary statistical analysis was performed on probable risk factors for treatment failure. Results: In total, 78 patients with chronic cavitary long bone osteomyelitis were included. Follow-up was at least 12 months (mean 46; standard deviation, SD, 20), and 69 patients were treated in a one-stage procedure. Overall infection eradication was 85 %, and 1-year infection-free survival was 89 %. Primary closure versus local/muscular flap coverage is the only risk factor for treatment failure. Conclusion: With 85 % eradication of infection, S53P4 bioactive glass is an effective biomaterial in the treatment of chronic osteomyelitis in a one-stage procedure. A major risk factor for treatment failure is the necessity for local/free muscle flap coverage. These results confirm earlier published data, and together with the fundamentally different antimicrobial pathways without antibiotic resistance, S53P4 bioactive glass is a recommendable biomaterial for chronic osteomyelitis treatment and might be beneficial over other biomaterials.

Validation of a finite element model of the thoracolumbar spine to study instrumentation level variations in early onset scoliosis correction.

Growth-guidance constructs are an alternative to growing rods for the surgical treatment of early onset scoliosis (EOS). Constructs containing ultra-high molecular weight polyethylene (UHMWPE) sublaminar tape have been proposed as an improvement to the traditional Luque trolley. Ideally, a certain minimum number of levels is instrumented, thus offering the best balance between providing adequate spinal fixation and minimizing surgical exposure and spinal mobility reduction. The objective of the current study was to validate a parametric FE model of the thoracolumbar spine including its ability to predict the biomechanical effects of varying the number of levels instrumented with UHMWPE sublaminar tape in a growth-guidance construct for EOS correction. In a first step, the material properties of the L4-L5 segment in the model were calibrated relative to literature data. Next, whole thoracolumbar spine behavior was verified relative to literature data as well. Subsequently, rods, screws, and sublaminar tape were implemented in the model and a simulation of a previously performed in vitro experiment, in which the range of motion (ROM) of porcine spine segments was measured for different tape configurations, was performed. Good agreement between in vitro and FE-results was found for the changes in ROM before and after instrumentation. Good agreement for changes in ROM was obtained when varying the number of instrumented levels as well, indicating that the model can be a useful tool to evaluate the effects of construct composition variations. The present study was limited by the fact that only normal spine curvatures were analyzed and the fact that results of porcine spine experiments were compared to results of human FE models. Nevertheless, the good agreement in results, even at a detailed level, supports the idea that the model can ultimately be used as a pre-operative planning tool to evaluate different construct designs. The FE model of the thoracolumbar spine was successfully validated and was able to capture the biomechanical effect of construct component variations.

Biomechanical comparison of semirigid junctional fixation techniques to prevent proximal junctional failure after thoracolumbar adult spinal deformity correction.

BACKGROUND CONTEXT: Adult spinal deformity patients treated operatively by long-segment instrumented spinal fusion are prone to develop proximal junctional kyphosis (PJK) and failure (PJF). A gradual transition in range of motion (ROM) at the proximal end of spinal instrumentation may reduce the incidence of PJK and PJF, however, previously evaluated techniques have not directly been compared. PURPOSE: To determine the biomechanical characteristics of five different posterior spinal instrumentation techniques to achieve semirigid junctional fixation, or "topping-off," between the rigid pedicle screw fixation (PSF) and the proximal uninstrumented spine. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Seven fresh-frozen human cadaveric spine segments (T8-L3) were subjected to ex vivo pure moment loading in flexion-extension, lateral bending and axial rotation up to 5 Nm. The native condition, three-level PSF (T11-L2), PSF with supplemental transverse process hooks at T10 (TPH), and two sublaminar taping techniques (knotted and clamped) as one- (T10) or two-level (T9, T10) semirigid junctional fixation techniques were compared. The ROM and neutral zone (NZ) of the segments were normalized to the native condition. The linearity of the transition zones over three or four segments was determined through linear regression analysis. RESULTS: All techniques achieved a significantly reduced ROM at T10-T11 in flexion-extension and axial rotation relative to the PSF condition. Additionally, both two-level sublaminar taping techniques (CT2, KT2) had a significantly reduced ROM at T9-T10. One-level clamped sublaminar tape (CT1) had a significantly lower ROM and NZ compared with one-level knotted sublaminar tape (KT1) at T10-T11. Linear regression analysis showed the highest linear correlation between ROM and vertebral level for TPH and the lowest linear correlation for CT2. CONCLUSIONS: All studied semirigid junctional fixation techniques significantly reduced the ROM at the junctional levels and thus provide a more gradual transition than pedicle screws. TPH achieves the most linear transition over three vertebrae, whereas KT2 achieves that over four vertebrae. In contrast, CT2 effectively is a one-level semirigid junctional fixation technique with a shift in the upper rigid fixation level. Clamped sublaminar tape reduces the NZ greatly, whereas knotted sublaminar tape and TPH maintain a more physiologic NZ. Clinical validation is ultimately required to translate the biomechanics of various semirigid junctional fixation techniques into the clinical goal of reducing the incidence of proximal junctional kyphosis and failure. CLINICAL SIGNIFICANCE: The direct biomechanical comparison of multiple instrumentation techniques that aim to reduce the incidence of PJK after thoracolumbar spinal fusion surgery provides a basis upon which clinical studies could be designed. Furthermore, the data provided in this study can be used to further analyze the biomechanical effects of the studied techniques using finite element models to better predict their post-operative effectiveness.

Post-marketing surveillance on safety and efficacy of posterior spinal correction and fusion with the CD Horizon Solera instrumentation for adolescent idiopathic scoliosis. A retrospective cohort study.

BACKGROUND: Post-Market Clinical Follow-Up has been integrated into the new Medical Device Regulations since 2020. The CD Horizon Solera 4.75 mm instrumentation (CD-Solera) was introduced worldwide in 2009, and specifically intended for surgical treatment of pediatric and adolescent scoliosis patients. The objective of this study was to evaluate the safety and efficacy of the CD-solera 4.75 instrumentation in surgical treatment of adolescent idiopathic scoliosis (AIS). METHODS: 94 consecutive AIS patients, 82 female, 12 male, who underwent posterior correction with CD-Solera instrumentation between 2010 and 2016 at age 14.8 ± 1.6 years, were retrospectively included. The minimum follow-up was two years. On pre- and postoperative biplanar full spine radiographs Cobb angles of the primary and secondary curves and sagittal profile were measured before surgery, immediately postoperative, and at two-year follow-up. Medical records were reviewed for complications. Clinical outcome was analyzed using theSRS-22r questionnaire. RESULTS: In this study 77% of the patients had a structural thoracic curve (type Lenke 1 or 2), and 23% had a structural (thoraco-)lumbar curve (Lenke 3-6). A correction of 55.1% and 51.7% was achieved respectively immediately post-operative, and at last-year follow up for the primary curve. The mean loss of correction was 2°. Health related quality of life was 4.0 (good) on the SRS-22r-questionnaire. In total six revision operations were executed, of which one was related to the material (rod breakage). Other reasons for revision operation were not due to the material. No neurological problems were encountered. CONCLUSION: In patients with AIS the initial correction and maintenance of correction as achieved by posterior spinal fusion using the CD-Solera instrumentation, is comparable to other reported devices. Complication rates are low and health related quality of life comparable to literature. The CD-Solera can be regarded as a safe and effective instrumentation in surgical treatment of AIS.

Patient-Specific Variations in Local Strain Patterns on the Surface of a Trussed Titanium Interbody Cage.

Introduction: 3D printed trussed titanium interbody cages may deliver bone stimulating mechanobiological strains to cells attached at their surface. The exact size and distribution of these strains may depend on patient-specific factors, but the influence of these factors remains unknown. Therefore, this study aimed to determine patient-specific variations in local strain patterns on the surface of a trussed titanium interbody fusion cage. Materials and Methods: Four patients eligible for spinal fusion surgery with the same cage size were selected from a larger database. For these cases, patient-specific finite element models of the lumbar spine including the same trussed titanium cage were made. Functional dynamics of the non-operated lumbar spinal segments, as well as local cage strains and caudal endplate stresses at the operated segment, were evaluated under physiological extension/flexion movement of the lumbar spine. Results: All patient-specific models revealed physiologically realistic functional dynamics of the operated spine. In all patients, approximately 30% of the total cage surface experienced strain values relevant for preserving bone homeostasis and stimulating bone formation. Mean caudal endplate contact pressures varied up to 10 MPa. Both surface strains and endplate contact pressures varied more between loading conditions than between patients. Conclusions: This study demonstrates the applicability of patient-specific finite element models to quantify the impact of patient-specific factors such as bone density, degenerative state of the spine, and spinal curvature on interbody cage loading. In the future, the same framework might be further developed in order to establish a pipeline for interbody cage design optimizations.

Ultra-high-molecular-weight polyethylene sublaminar tape as semirigid fixation or pedicle screw augmentation to prevent failure in long-segment spine surgery: an ex vivo biomechanical study.

OBJECTIVE: Complications after adult spinal deformity surgery are common, with implant-related complications occurring in up to 27.8% of cases. Sublaminar wire fixation strength is less affected by decreasing trabecular bone density in comparison to pedicle screw (PS) fixation due to the predominant cortical bone composition of the lamina. Sublaminar fixation may thus aid in decreasing implant-related complications. The goal of this study was to compare fixation characteristics of titanium sublaminar cables (SCs), ultra-high-molecular-weight polyethylene (UHMWPE) tape, PSs, and PSs augmented with UHMWPE tape in an ex vivo flexion-bending setup. METHODS: Thirty-six human cadaver vertebrae were stratified into 4 different fixation groups: UHMWPE sublaminar tape (ST), PS, metal SC, and PS augmented with ST (PS + ST). Individual vertebrae were embedded in resin, and a flexion-bending moment was applied that closely resembles the in vivo loading pattern at transitional levels of spinal instrumentation. RESULTS: The failure strength of PS + ST (4522 ± 2314 N) was significantly higher compared to the SC (2931 ± 751 N) and PS (2678 ± 827 N) groups, which had p values of 0.028 and 0.015, respectively (all values expressed as the mean ± SD). Construct stiffness was significantly higher for the PS groups compared to the stand-alone sublaminar wiring groups (p = 0.020). In contrast to SC, ST did not show any case of cortical breach. CONCLUSIONS: The higher failure strength of PS + ST compared to PS indicates that PS augmentation with ST may be an effective measure to reduce the incidence of screw pullout, even in osteoporotic vertebrae. Moreover, the lower stiffness of sublaminar fixation techniques and the absence of damage to the cortices in the ST group suggest that ST as a stand-alone fixation technique in adult spinal deformity surgery may also be clinically feasible and offer clinical benefits.

Insight into the possible aetiologies of Blount's disease: a systematic review of the literature.

Blount's disease or bowed leg deformity, is a unilateral or bilateral growth deformity of the medial proximal tibia that leads to a tibial varus deformity. A distinction can be made in an early and late onset type. The disease seems to have a predisposition for certain descends. Since the first publication of Blount's disease, different hypotheses on the aetiology are proposed but no consensus exists. The objective of this study is to provide an overview of the available hypotheses on the aetiology of Blount's disease since its first description and assessment of the available level of evidence, the quality of evidence and the occurrence of bias supporting these individual hypotheses. A systematic search according to the PRISMA statement was conducted using PubMed, MEDLINE, EMBASE and the Cochrane Library using a broad combination of terminology to ascertain a complete selection. Proper MESH search criteria were formulated and the bibliographic search was limited to English and Dutch language articles. Articles with no mention of aetiology or a disease related to Blount's were excluded. Level of evidence and types of bias were assessed. Thirty-two articles that discuss the aetiology of Blount's disease were selected. A variety of hypotheses was postulated in these articles with most research in the field of increased mechanical pressure (obesity, early walking age) and race (descend). Blount's disease most likely has a multifactorial origin with influence of genetic and racial predisposition, increased mechanical pressure on the growth plate as a consequence of obesity or early walking age and possibly also nutrition. However, the exact aetiology remains unclear, the probable explanation is that multifactorial factors are all contributing to the development of Blount's disease. Histological research has shown that a disorganization of bone and cartilage structures on the medial side of the proximal tibial physis is present in patients with Blount's disease. Based on the available evidence on the aetiology of Blount's disease, we conclude that it is multifactorial. Most papers focus only on one hypotheses of Blount's disease occurrence and all are characterized as low level of evidence. There seems to be a preference for certain descends. Further research on especially genetic predisposition is needed to provide more insight in this factor of Blount's disease.

Cost-Effectiveness Study of One-Stage Treatment of Chronic Osteomyelitis with Bioactive Glass S53P4.

This study was set up to evaluate the costs of a one-stage treatment of chronic osteomyelitis using bioactive glass S53P4 versus a two-stage treatment using gentamicin-loaded PMMA beads. Furthermore, a cost-effectiveness analysis was performed from a hospital's perspective together with the evaluation of clinical outcome. A treatment group (n = 25) receiving one-stage surgery with bioactive glass was retrospectively compared with a two-stage control group (n = 25). An assessment was made of all costs included from first outpatient visit until one year after treatment. Bootstrap simulation and sensitivity analyses were performed. The primary endpoint was cost-effectiveness with clinical outcome as the secondary endpoint. The base case analyses shows dominance of the one-stage treatment with bioactive glass S53P4 due to lower costs and a better clinical outcome. Sensitivity analyses confirm these findings. This study is the first in its kind to show one-stage treatment of chronic osteomyelitis with bioactive glass S53P4 to be cost-effective.

Radiopaque UHMWPE sublaminar cables for spinal deformity correction: Preclinical mechanical and radiopacifier leaching assessment.

Polymeric sublaminar cables have a number of advantages over metal cables in the field of spinal deformity surgery, with decreased risk of neurological injury and potential for higher correction forces as the two most predominant. However, currently available polymer cables are radiolucent, precluding postoperative radiological assessment of instrumentation stability and integrity. This study provides a preclinical assessment of a woven UHMWPE cable made with radiopaque UHMWPE fibers. Our primary goal was to determine if the addition of a radiopacifier negatively affects the mechanical properties of UHMWPE woven cables. Tensile mechanical properties were determined and compared to suitable controls. Radiopacity was evaluated and radiopacifier leaching was assessed in vitro and in vivo. Finally, in vivo bismuth organ content was quantified after a 24-week implantation period in sheep. Results show that the mechanical properties of woven UHMWPE cables were not deleteriously affected by the addition of homogenously dispersed bismuth oxide particles within each fiber. Limited amounts of bismuth oxide were released in vitro, well below the toxicological threshold. Tissue concentrations lower than generally accepted therapeutic dosages for use against gastrointestinal disorders, well below toxic levels, were discovered in vivo. These results substantiate controlled clinical introduction of these radiopaque UHMWPE cables. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 771-779, 2018.