Aims. Our objective was to conduct a systematic review and meta-analysis, to establish whether differences arise in clinical outcomes between autologous and synthetic bone grafts in the operative management of tibial plateau fractures. Methods. A structured search of MEDLINE, EMBASE, the online archives of Bone & Joint Publishing, and CENTRAL databases from inception until 28 July 2021 was performed. Randomized, controlled, clinical trials that compared autologous and synthetic bone grafts in tibial plateau fractures were included. Preclinical studies, clinical studies in paediatric patients, pathological fractures, fracture nonunion, or chondral defects were excluded. Outcome data were assessed using the Risk of Bias 2 (ROB2) framework and synthesized in random-effect meta-analysis. The Preferred Reported Items for Systematic Review and Meta-Analyses guidance was followed throughout. Results. Six studies involving 353 fractures were identified from 3,078 records. Following ROB2 assessment, five studies (representing 338 fractures) were appropriate for meta-analysis. Primary outcomes showed non-significant reductions in articular depression at immediate postoperative (mean difference -0.45 mm, p = 0.25, 95%confidence interval (CI) -1.21 to 0.31, I. 2. = 0%) and long-term (> six months, standard mean difference -0.56, p = 0.09, 95% CI -1.20 to 0.08, I. 2. = 73%) follow-up in synthetic bone grafts. Secondary outcomes included mechanical alignment, limb functionality, and defect site pain at long-term follow-up, perioperative blood loss, duration of surgery, occurrence of surgical site infections, and secondary surgery. Mean blood loss was lower (90.08 ml, p < 0.001, 95% CI 41.49 to 138.67) and surgery was shorter (16.17 minutes, p = 0.04, 95% CI 0.39 to 31.94) in synthetic treatment groups. All other secondary measures were statistically comparable. Conclusion. All studies reported similar methodologies and patient populations; however, imprecision may have arisen through performance variation. These findings supersede previous literature and indicate that, despite perceived biological advantages, autologous bone grafting does not demonstrate superiority to synthetic grafts. When selecting a void filler, surgeons should consider patient comorbidity, environmental and societal factors in provision, and perioperative and postoperative care provision. Cite this article: Bone Jt Open 2022;3(3):218–228

Aim: We conducted a prospective, randomised study of 50 patients, 40 (80%) male and 10 (20%) female, with anterior cruciate ligament (ACL) rupture to compare the results of ligament reconstruction by middle third patellar tendon graft (M) or synthetic Leeds-Keio (LK) ligament.

Method: The patients were randomised into two groups. 26 (52%) underwent PTG repair and 24 (48%) LK repair. Subjective knee function was classified using the Lysholm score, Tegner activity score and IKDC grading. Laxity was tested by clinical examination including anterior draw, pivot shift and arthrometric measurements using the Stryker Laxometer (Stryker Corporation, Kalamazoo, Michigan, USA).

Results: We present the early (two to five-year follow-up) results of this on-going trial. There was no statistical difference between the two groups in activity levels, both pre-injury and current. However, both pivot shift and anterior laxity were significantly greater in the LK group at two years and greater.

Discussion: While the LK group did develop significantly greater laxity, it is demonstrated that the functional outcome is not affected. We conclude therefore that if the results of surgery were to be based on a functional outcome rather than objective measurements of laxity, it would seem logical that the LK is an acceptable alternative to autogenous PTG.

However whilst function appears to be as good the less successful objective criteria do suggest reservations for the long term results of the Leeds-keio graft.

Synthetic graft expanders have recently been developed for use in impaction grafting revision hip arthroplasty, but their true role has yet to be determined. We performed a series of experiments to investigate the properties of one such porous hydroxyapatite material (IG-Pore, ApaTech Ltd). IG-Pore was mixed with fresh-frozen human allograft chips and impacted into composite femoral models with a similar biomechanical profile to human bone (Sawbones Europe). Exeter hip prostheses (Stryker Howmedica Ltd) were implanted with cement and each model was axially loaded for 18000 cycles at physiological levels using an Instron servohydraulic materials testing machine. Four test groups with 0%, 50%, 70% and 90% IG-Pore were used, and there were eight femora in each group. Pre- and post-loading radiostereometric analysis was performed to characterise migration of the prosthesis. Total subsidence was measured and was separated into that occurring at the prosthesis-cement and cement-femur interfaces. Cyclical compression and expansion of the graft-containing models was measured using the Instron. Median values (interquartile range) for total subsidence were 0.43 mm (0.28 to 0.55) for the pure allograft group, 0.31 mm (0.20 to 0.55) for the 50% IG-Pore group, 0.23 mm (0.07 to 0.34) for the 70% allograft group and 0.13 mm (0.06 to 0.18) for the 90% IG-Pore group. These differences were statistically significant (p=0.034, Kruskal-Wallis). Subsidence at the prosthesis-cement interface was also lower for IG-Pore containing models (p=0.019, Kruskal-Wallis), although there was no significant difference at the cement-femur interface. Specimens with a higher proportion of IG-Pore showed smaller cyclical movements on loading (p=0.005, ANOVA). Higher proportions of IG-Pore do appear to reduce subsidence in a mechanical model of impaction grafting. A randomised clinical trial using RSA to compare a 50% IG-Pore/allograft mix with pure allograft is in progress to investigate the use of this material as a bone graft expander in the clinical setting

Impaction grafting procedures have found a widespread role in revision hip arthroplasty. Synthetic graft expanders have recently been introduced, but the optimal ratio of expander to allograft is unknown. We performed a series of in vitro experiments to investigate the optimal ratio for one commercially available porous hydroxyapatite material (IG-Pore, ApaT-ech Ltd). IG-Pore was mixed with fresh frozen human allograft chips from osteoarthritic femoral heads and with blood. Graft was impacted into fibre-glass femoral models (Sawbones Europe) with a similar biomechanical profile to human bone, and Exeter hip prostheses (Stryker Howmedica Ltd) were cemented in place. Each model was loaded using an Instron servohydraulic materials testing machine for 18000 cycles. The magnitude and frequency of the loading cycle was based on physiologically measured values. Four test groups with 0%, 50%, 70% and 90% IG-Pore were used, with eight femora in each group. Tantalum marker beads were attached to the prosthesis, the femoral model and the cement mantle, and radio-stereometric analysis (RSA) was performed pre- and post- loading to determine migration and rotation of the prosthesis in each axis. Pre-loading films were repeated in sixteen cases for precision measurements, and twelve specimens had delayed post-loading films performed to measure any re-expansion of the unloaded graft. The primary end-point was RSA-measured subsidence of the prosthesis, defined as vertical movement of the tip. Median subsidence was 0.43mm, 0.31mm, 0.24mm and 0.13mm in the 0%, 50%, 70% and 90% IG-Pore groups respectively (P=0.034, Kruskal-Wallis test). The precision, given as the median absolute difference, was 0.0065mm. All specimens showed a cyclical compression and expansion throughout the loading cycle. Specimens with a higher proportion of IG-Pore tended to be more resistant to this and the mean values for cyclical movement were 1.76 0.27mm, 1.65 0.21mm, 1.57 0.18 mm and 1.45 0.14mm for the 0%, 50%, 70% and 90% IG-Pore groups. Higher proportions of IG-Pore appear to reduce subsidence in impaction grafting. Other issues such as the handling qualities of the graft and the biological effect of synthetic materials also need to be considered, however. A randomised clinical trial using RSA to evaluate a 50% IG-Pore/allograft mix in comparison to pure allograft is ongoing in our institution, and we hope that this will answer some of these questions definitively

Introduction: Impaction allografting is an established method for restoring deficient bone during revision arthroplasty of the hip. Graft augmentation with synthetic materials has been proposed and evaluated experimentally. Our aim was to assess clinically whether migration and wear of implants with a synthetic graft mix would be equivalent to pure allograft. Materials and Methods: Patient inclusion criteria were: acetabular and or femoral defects from aseptically loosened primary THR undergoing cemented revision with impaction grafting; age 55–80 years; initial diagnosis of osteo arthritis; good health with reasonable daily activity level. Patients were randomized to receive either pure allograft or a 50% mixture with a porous hydroxyapatite material (Apapore60, Apatech, UK). Revision was with the Exeter stem, antibiotic Simplex cement (Stryker Howmedica Ltd), and Ogee cup (Depuy Int. Ltd., Leeds, UK). Tantalum markers were inserted into the pelvis, cup, femur, cement and graft in order to measure migration with radiostereometry (RSA). Patients received a sequence of RSA examinations up to 2 years. A total of 26 patients (18 for the femur) have been analysed. Results: At 2 years no significant differences were seen in cup wear, or migration of the cup, femoral and pelvic graft markers. Stem migration occurred mainly at the stem cement interface. The rate of distal migration for the femoral head was greater for pure allograft in the first year (p < 0.05), however this rate reduced significantly in year two. Higher medial migration in year one was observed for the proximal medial cement mantle for allograft (p < 0.05). Conclusions: Improved stability and normal cup wear were observed in a randomized clinical study for a synthetically augmented allograft. This agrees with experimental findings. 1. Longer follow up with increased patient numbers is recommended to confirm these findings

Autologous osteochondral grafting has demonstrated positive outcomes for treating articular cartilage defects by replacing the damaged region with a cylindrical graft consisting of bone with a layer of cartilage, taken from a non-loadbearing region of the knee. Despite positive clinical use, factors that cause graft subsidence or poor integration are relatively unknown. The aim of this study was to develop finite element (FE) models of osteochondral grafts within a tibiofemoral joint and to investigate parameters affecting osteochondral graft stability. Initial experimental tests on cadaveric femurs were performed to calibrate the bone properties and graft-bone frictional forces for use in corresponding FE models, generated from µCT scan data. The effects of cartilage defects and osteochondral graft repair were measured by examining contact pressure changes using in vitro tests on a single cadaveric human tibiofemoral joint. Six defects were created in the femoral condyles which were subsequently treated with osteochondral autografts or metal pins. Matching µCT scan-based FE models were created, and the contact patches were compared. Sensitivity to graft bone properties was investigated. The bone material properties and graft-bone frictional forces were successfully calibrated from the initial tests with good resulting levels of agreement (CCC=0.87). The tibiofemoral joint experiment provided a range of cases to model. These cases were well captured experimentally and represented accurately in the FE models. Graft properties relative to host bone had large effects on immediate graft stability despite limited changes to resultant cartilage contact pressure. Model confidence was built through extensive validation and sensitivity testing, and demonstrated that specimen-specific properties were required to accurately represent graft behaviour. The results indicate that graft bone properties affect the immediate stability, which is important for the selection of allografts and design of future synthetic grafts. Acknowledgements. Supported by the EPSRC-EP/P001076

In 2021 the bone grafting market was worth €2.72 billion globally. As allograft bone has a limited supply and risk of disease transmission, the demand for synthetic grafting substitutes (BGS) continues to grow while allograft bone grafts steadily decrease. Synthetic BGS are low in mechanical strength and bioactivity, inspiring the development of novel grafting materials, a traditionally laborious and expensive process. Here a novel BGS derived from sustainably grown coral was evaluated. Coral-derived scaffolds are a natural calcium carbonate bio-ceramic, which induces osteogenesis in bone marrow mesenchymal stem cells (MSCs), the cells responsible for maintaining bone homeostasis and orchestrating fracture repair. By 3D printing MSCs in coral-laden bioinks we utilise high throughput (HT) fabrication and evaluation of osteogenesis, overcoming the limitations of traditional screening methods. MSC and coral-laden GelXA (CELLINK) bioinks were 3D printed in square bottom 96 well plates using a CELLINK BIO X printer with pneumatic adapter Samples were non-destructively monitored during the culture period, evaluating both the sample and the culture media for metabolism (PrestoBlue), cytotoxicity (lactose dehydrogenase (LDH)) and osteogenic differentiation (alkaline phosphatase (ALP)). Endpoint, destructive assays used included qRT-PCR and SEM imaging. The inclusion of coral in the printed bioink was biocompatable with the MSCs, as reflected by maintained metabolism and low LDH release. The inclusion of coral induced osteogenic differentiation in the MSCs as seen by ALP secretion and increased RUNX2, collagen I and osteocalcin transcription. Sustainably grown coral was successfully incorporated into bioinks, reproducibly 3D printed, non-destructively monitored throughout culture and induced osteogenic differentiation in MSCs. This HT fabrication and monitoring workflow offers a faster, less labour-intensive system for the translation of bone substitute materials to clinic. Acknowledgements: This work was co-funded by Enterprise Ireland and Zoan Biomed through Innovation Partnership IP20221024

Bone defects can result from different incidents such as acute trauma, infection or tumor resection. While in most instances bone healing can be achieved given the tissue's innate ability of self-repair, for critical-sized defects spontaneous regeneration is less likely to occur, therefore requiring surgical intervention. Current clinical procedures have failed to adequately address this issue. For this reason, bone tissue engineering (BTE) strategies involving the use of synthetic grafts for replacing damaged bone and promoting the tissue's regeneration are being investigated. The electrical stimulation (ES) of bone defects using direct current has yielded very promising results, with neo tissue formation being achieved in the target sites in vivo. Electroactive implantable scaffolds comprised by conductive biomaterials could be used to assist this kind of therapy by either directing the ES specifically to the damaged site or promoting the integration of electrodes within the bone tissue as a coating. In this study, we developed novel conductive heat-treated polyacrylonitrile/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PAN/PEDOT:PSS) nanofibers via electrospinning capable of mimicking key native features of the bone tissue's extracellular matrix (ECM) and providing a platform for the delivery of exogenous ES. The developed scaffolds were doped with sulfuric acid and mineralized in Simulated Body Fluid to mimic the inorganic phase of bone ECM. As expected, the doped PAN/PEDOT:PSS nanofibers exhibited electroconductive properties and were able to preserve their fibrous structure. The addition of PEDOT:PSS was found to improve the bioactivity of the scaffolds, with a more significant in vitro mineralization being obtained. By seeding the scaffolds with MG-63 osteoblasts and human mesenchymal stem/stromal cells, an increased cell proliferation was observed for the mineralized PAN/PEDOT:PSS nanofibers, which also registered an increased expression of key osteogenic markers (e.g Osteopontin). Our findings appear to corroborate the promising potential of the generated nanofibers for future ES-based BTE applications. Acknowledgements: The authors thank FCT for funding through the projects InSilico4OCReg (PTDC/EME-SIS/0838/2021), BioMaterARISES (EXPL/CTM-CTM/0995/2021) and OptiBioScaffold (PTDC/EME-SIS/32554/2017, POCI-01- 0145-FEDER- 32554), the PhD scholarship (2022.10572.BD) and through institutional funding to iBB (UIDB/04565/2020 and UIDP/04565/2020), Associate Laboratory i4HB (LA/P/0140/2020) and IT (UIDB/50008/2020)

Knee dislocations are a rare but serious cause of trauma. The aim of this study was to establish current demographics and injury patterns/associations in multi-ligament (MLI) knee injuries in the United Kingdom. A National survey was sent out to trauma & orthopaedic trainees using the British Orthopaedic Trainees Association sources in 2018. Contributors were asked to retrospectively collect a data for a minimum of 5 cases of knee dislocation, or multi-ligament knee injury, between January 2014 and December 2016. Data was collected regarding injury patterns and surgical reconstructions. 73 cases were available for analysis across 11 acute care NHS Trusts. 77% were male. Mean age was 31.9 (SD 12.4; range 16–69). Mean Body Mass Index (BMI) was 28.3 (SD 7.0; range 19–52). Early (<3 weeks) reconstruction was performed in 53% with 9 (23%) patients under-going procedures for arthrofibrosis. Late (>12 weeks) reconstruction took place in 37% with one (3.7%) patient under-going arthroscopic arthrolysis. 4% had delayed surgery (3–12 weeks) and 5% had early intervention with delayed ACL reconstruction. For injuries involving 3 or more ligament injuries graft choices were ipsilateral hamstring (38%), bone-patella tendon-bone (20%), allograft (20%), contralateral hamstring (17%) and synthetic grafts in 18%. Multi-ligament knee injuries are increasingly being managed early with definitive reconstructions. This is despite significant risk of arthrofibrosis with early surgery. Ipsilateral and contralateral hamstring grafts make up the bulk of graft choice however allograft (20%) and synthetic grafts (18%) remain popular

Abstract. Introduction. Traumatic knee dislocations are devastating injuries and there is no single best accepted treatment. This study looked at functional outcome of a single surgeon case series of patients who underwent surgical management of their knee dislocation. Methods. Eighty-seven patients with knee dislocation were treated at a major trauma centre. Acute surgical repair and reconstruction with fracture fixation within 4 weeks was preferred unless the patient was too unstable (Injury severity score>16). The collaterals were repaired and augmented using a variety of autografts, allografts or synthetic grafts. PCL was primarily braced and reconstructed subsequently, if required. Outcome was collected prospectively using IKDC score, KOOS and Tegner score. Results. The mean age of the patients was 33.6yrs (SD 11.9), 66 males and 21 females. According to Schenck classification, 26 were KD-I (30%), 6 KD-II (7%), 13 were KD-III (15%), 7 were KD-IV (8%) and 35 were KD-V (40%). 7 patients had CPN injury (8%), 3 had vascular injury (3.4%), 2 had combined CPN and vascular injury (2.3%). Acute surgical treatment was done in 62 patients while 10 had staged reconstruction. 22 patients had delayed reconstruction. The mean follow-up period was 5.8 years (1- 12 yrs), mean IKDC score was 57.6 (SD 23.6). The mean Tegner activity scale postoperatively was 4.5(SD 2) and the mean KOOS score was 74.9 (SD 19.6). Conclusion. A large proportion of cases were KD-V but still had a good outcome with surgical management. Current classification systems do not cover all dislocation patterns and a modification is proposed

Introduction. Crossover and claw toe deformity has traditionally been a very difficult condition to manage surgically, with high recurrence rates. Multiple methods have been used to treat this condition. Plantar plate “repair” has recently been advocated, with sutures used to repair an assumed tear. Based on clinical experience and anatomical studies (Deland et al. 1995), we believe the main pathology is a distal migration of the plantar plate complex resulting in exposure of the metatarsal to the thin posterior synovial attachment of the plate. The downward forces on the metatarsal head results in herniation of the head inferiorly. Accordingly we have developed a technique using full cuff release of the plantar plate complex that includes complete release of the collateral ligaments, repositioning the plantar plate anatomically and reinforcing the hernial defect with a synthetic mesh graft. Methods. 12 cases of severe crossover toe deformity have undergone plantar plate reconstruction using synthetic mesh graft in addition to other bony procedures (e.g. Weil's osteotomy, PIPJ fusion) since 2015 operated upon by the lead author. We collated data regarding patient satisfaction using Coughlin's Score (Coughlin 1991). We have also evaluated the sustainability of correction and any complications. Results. All patients reported “excellent” outcomes using Coughlin's score, with no cases of recurrence of any significance or complications, and a mean time to follow up of 180 days (range 23–23). Conclusions. Our understanding of the pathology of this condition is somewhat different from the conventional wisdom. Our technique of using a synthetic mesh graft to reconstruct the plantar plate complex shows promising results in terms of safety and decreased recurrence rate compared to traditional techniques. Further long term prospective results are required to confirm this pilot data

Current strategies for bone repair have accepted limitations and the search for synthetic graft materials or for scaffolds that will support ex vivo bone tissue engineering continues. Bioprospecting has led to increased interest in potential applications for marine organisms and their by-products and biomimetic strategies have led to the investigation of naturally occurring porous structures as templates for bone growth. As a rich source of mineralising porous organisms, our seas and oceans could provide new directions for bone tissue engineering that may enhance in vivo and ex vivo bone formation

The purpose of the study was to evaluate the outcome of curettage and grafting with calcium sulfate pellets for progressive retroacetabular osteolysis with retention of the acetabular component. Seven patients who underwent the procedure were evaluated clinically and radiographically at an average follow-up time of fifteen months. There was no progression of osteolysis following curettage and grafting with good to excellent osseo-integration. All patients had a good functional outcome with no pain during follow-up. Curettage and synthetic grafting of retroacetabular cysts with calcium sulfate pellets is a viable option in halting the progression of retroacetabular lysis and promoting osseous recovery. The purpose of this study was to evaluate outcome of curettage and grafting of progressive retroacetabular osteolysis with calcium sulfate pellets and retention of components. Restoration of retroacetabular bone stock by curettage and grafting with synthetics would obviate the need for autogenous bone graft and its associated risks. Retention of well-fixed acetabular components also aids in prevention of further bone loss associated with component extraction. We conducted a clinical and radiographic review of seven patients who presented to the senior author with radiographic findings of progressive retroacetabular osteolysis. All patients were treated with curettage and filling of the defects with calcium sulfate. Mean follow-up time is fifteen (five to twenty-seven) months. Polyethylene wear was noted in all cases. The size of the lesions ranged from 3.1 x 2.0 to 9.0 x 5.3 cm. On follow-up evaluation, there was no recurrence or progression of the lesions. Osseo-integration was excellent in four cases and good in three cases. All patients had returned to normal level of function with no pain. Patients with retroacetabular osteolysis are often asymptomatic until catastrophic failure occurs as a result of extensive bone loss. Treatment of retroacetabular osteolysis in the setting of well-fixed components is controversial. Retention of the components, curettage and synthetic grafting with calcium sulfate is a viable option to prevent progression of lysis and stimulate bone formation. Curettage and grafting of progressive retroacetabular osteolysis with calcium sulfate and retention of components results in good osseo-integration of the graft and halts the progression of lysis

The rate of fracture and subsequent nonunion after radiation therapy for soft-tissue sarcomas and bone tumors has been demonstrated to quite high. There is a paucity of data describing the optimal treatment for these nonunions. Free vascularized fibular grafts (FVFG) have been used successfully in the treatment of large segmental bone defects in the axial and appendicular skeleton, however, their efficacy with respect to treatment of radiated nonunions remains unclear. The purpose of the study was to assess the 1) union rate, 2) clinical outcomes, and 3) complications following FVFG for radiation-induced femoral fracture nonunions. We identified 24 patients who underwent FVFG for the treatment of radiation-induced femoral fracture nonunion between 1991 and 2015. Medical records were reviewed in order to determine oncologic diagnosis, total preoperative radiation dose, type of surgical treatment for the nonunion, clinical outcomes, and postoperative complications. There were 11 males and 13 females, with a mean age of 59 years (range, 29 – 78) and a mean follow-up duration of 61 months (range, 10 – 183 months). Three patients had a history of diabetes mellitus and three were current tobacco users at the time of FVFG. No patient was receiving chemotherapy during recovery from FVFG. Oncologic diagnoses included unspecified soft tissue sarcomas (n = 5), undifferentiated pleomorphic sarcoma (UPS) (n = 3), myxofibrosarcoma (n = 3), liposarcoma (n = 2), Ewing's sarcoma (n = 2), lymphoma (n = 2), hemangiopericytoma, leiomyosarcoma, multiple myeloma, myxoid chondrosarcoma, myxoid liposarcoma, neurofibrosarcoma, and renal cell carcinoma. Mean total radiation dose was 56.3 Gy (range, 39 – 72.5), given at a mean of 10.2 years prior to FVFG. The average FVFG length was 16.4 cm. In addition to FVFG, 13 patients underwent simultaneous autogenous iliac crest bone grafting, nine had other cancellous autografting, one received cancellous allograft, and three were treated with synthetic graft products. The FVFG was fixed as an onlay graft using lag screws in all cases, additional fixation was obtained with an intramedullary nail (n = 19), dynamic compression plate (n = 2), blade plate (n = 2), or lateral locking plate (n = 1). Nineteen (79%) fractures went on to union at a mean of 13.1 months (range, 4.8 – 28.1 months). Musculoskeletal Tumor Society scores improved from eight preoperatively to 22 at latest follow-up (p < 0.0001). Among the five fractures that failed to unite, two were converted to proximal femoral replacements (PFR), two remained stable pseudarthroses, and one was converted to a total hip arthroplasty. A 6th case did unite initially, however, subsequent failure lead to PFR. Seven patients (29%) required a second operative grafting. There were five additional complications including three infections, one wound dehiscence, and one screw fracture. No patient required amputation. Free vascularized fibular grafts are a reliable treatment option for radiation-induced pathologic femoral fracture nonunions, providing a union rate of 79%. Surgeons should remain cognizant, however, of the elevated rate of infectious complications and need for additional operative grafting procedures

The purpose of this study was to evaluate trabecular bone response, at fifty-two week follow-up, to four different synthetic graft materials (CaSO4 and CaSO4 – HA/TCP composites) as compared to autograft in a canine defect model. The group with the highest HA/ TCP proportion had the greatest amount of residual graft material and total mineralized material. Increasing the proportion of HA/TCP reduces the rate of dissolution, and appears to have little effect on bone formation at long term follow-up. This study further suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications. The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO4 and CaSO4 – HA/TCP composites) as compared to autograft in a canine defect model, at long term follow-up. Both 85% CaSO4 – 15% HA/TCP and 65% CaSO4 – 15% HA/TCP showed bone formation similar to autograft. The group with the highest proportion of HA/TCP lasted longer than the other formulations. The results suggest that increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in the current model. Results suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications. In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO4 – HA/TCP, autograft bone, or left unfilled. After sacrifice at six, twelve, twenty-six or fifty-two weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects. The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0001). This group contained the greatest amount of total mineralized material (graft material + bone) (p< 0.03. The extent of new bone formation increased from twelve to twenty-six weeks (p< 0.0001). Both 85% CaSO4 – 15% HA/TCP and 65% CaSO4 – 15% HA/TCP showed bone formation similar to autograft. Funding: Research grant from Stryker Howmedica, Matwah, NJ

The purpose of this study was to evaluate trabecular bone response to four different synthetic graft materials (CaSO. 4. and CaSO. 4. – HA/TCP composites) as compared to autograft in a canine defect model. The group with the highest HA/TCP proportion (and the lowest CaSO4 proportion) had the greatest amount of residual graft material and total mineralized material (p< 0.05). Increasing the proportion of HA/TCP reduces the rate of dissolution, and appears to have little effect on bone formation. This study suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications. Calcium sulfates and phosphates have become popular clinically for use as bone graft substitutes, however, their in-vivo performance has not been well characterized. The purpose of this study was to evaluate trabecular bone response to four synthetic graft materials (CaSO. 4. and CaSO. 4. – HA/TCP composites) as compared to autograft in a canine defect model. Both 100% CaSO. 4. and the 3 CaSO. 4. – HA/TCP formulations showed good bone formation. The group with the highest proportion of HA/TCP lasted longer than the other formulations, suggesting increased HA/TCP proportions reduce the rates of dissolution, without compromising bone formation in the current model. Results suggests that a range of composites could be created to match the spectrum of resorption rates demanded by clinical applications. In this REB-approved RCT, bilateral humeral and femoral cylindrical defects were filled with one of four types of pellets with varying proportions of CaSO. 4. – HA/TCP, autograft bone, or left unfilled. After sacrifice at six or twelve weeks, defect sites were evaluated histologically for tissue and inflammatory response, area fractions of residual graft material, and bone ingrowth in the defects. The area of the defect occupied by residual graft material in the group with the highest percentage of HA/TCP was greater than in other composite groups (p< 0.0006). At twelve weeks, this group contained more total mineralized material (graft material + bone) (p< 0.005). The extent of new bone formation was not different among the composite groups at either time-point, but all showed more bone formation than the empty defect. Funding: This study was funded by a research grant from Stryker Howmedica, Matwah, NJ

Anterior cruciate ligament (ACL) reconstruction is the current standard of care for ACL tears. However, the results are not consistently successful, autografts or allografts have certain disadvantages, and synthetic grafts have had poor clinical results. The aim of this study was to determine the efficacy of tissue engineering decellularized tibialis tendons by recellularization and culture in a dynamic tissue bioreactor. To determine if recellularization of decellularized tendons combined with mechanical stimulation in a bioreactor could replicate the mechanical properties of the native ACL and be successfully used for ACL reconstruction in vivo. Porcine tibialis tendons were decellularized and then recellularized with human adult bone marrow-derived stem cells. Tendons were cultured in a tissue bioreactor that provided biaxial cyclic loading for up to 7 days. To reproduce mechanical stresses similar to hose experienced by the ACL within the knee joint, the tendons were subjected to simultaneous tension and torsion in the bioreactor. Expression of tendon-specific genes, and newly synthesized collagen and glycosaminoglycan (GAG) were used to quantify the efficacy of recellularization and dynamic bioreactor culture. The mechanical strength of recellularized constructs was measured after dynamic stimulation. Finally, the tissue-engineered tendons were used to reconstruct the ACL in mini-pigs and mechanical strength was assessed after three months. Dynamic bioreactor culture significantly increased the expression of tendon-specific genes, the quantity of newly synthesized collagen and GAG, and the tensile strength of recellularized tendons. After in vivo reconstruction, the tensile strength of the tissue-engineered tendons increased significantly up to 3 months after surgery and were within 80% of the native strength of the ACL. Our translational study indicates that the recellularization and dynamic mechanical stimuli can significantly enhance matrix synthesis and mechanical strength of decellularized porcine tibialis tendons. This approach to tissue engineering can be very useful for ACL reconstruction and may overcome some of the disadvantages of autografts and allografts

Osteolysis has been reported following ACJ reconstruction with a synthetic graft. We present the first study into its prevalence and pattern, and its effect on patient outcome. Patients who underwent treatment of an unstable ACJ injury using the Surgilig/LockDown implant were identified via our database. Patients were invited to attend a dedicated outpatient clinic for clinical examination, radiographic evaluation, and completion of outcome scoring. Patients who were unable to attend were contacted by telephone. 49 patients were identified. We assessed 21 clinically at a mean of 7 years post-procedure (range 3–11 years). All had radiographic evidence of distal clavicle and coracoid osteolysis. We did not observe progression of osteolysis from the final post-operative radiographs. A further 13 were contacted by phone. The mean Oxford Shoulder Score was 43 (range 31–48) and mean DASH score was 8.5 (range 3–71). The average Patient Global Impression of Change score was 6 (range 2–7). Six patients underwent removal of a prominent screw at a mean of 2 years after surgery; the pattern of osteolysis was no different in this group. All patients had comparable abduction, forward flexion and internal rotation to their uninjured shoulder. We did not observe any relationship between patient demographics, position of implant or etiology and the pattern of osteolysis. Osteolysis of the distal clavicle and/or coracoid is always seen following synthetic reconstruction of the ACJ using this implant, but is non-progressive. Range of shoulder movement is largely unaffected and patient outcomes remain high

Complications involving the knee extensor mechanism occur in 1% to 12% of patients following total knee arthroplasty (TKA), and have negative effects on patient outcomes. While multiple reconstruction options have been described, the results in patients with a prior TKA are inferior to those in patients without a TKA. However, optimistic results have been reported by Browne and Hanssen with the use of a synthetic mesh (knitted monofilament polypropylene)3. In this technique, a synthetic graft is created by folding a 10 × 14 inch sheet of mesh and securing it with nonabsorbable sutures. A burr is then used to create a trough in the anterior aspect of the tibia to accept the mesh graft. The graft is inserted into the trough and secured with cement. After the cement cures, a transfixion screw with a washer is placed. A portal is subsequently created in the lateral soft tissues to allow delivery of the graft from deep to superficial. The patella and quadriceps tendon are mobilised, and the graft is secured with sutures to the lateral retinaculum, vastus lateralis, and quadriceps tendon. The vastus medialis is then mobilised in a pants-over-vest manner over the mesh graft, and secured with sutures. Finally, the distal arthrotomy is closed tightly to completely cover the mesh graft with host tissue. In their series, Browne and Hanssen noted that 9 of 13 patients achieved an extensor lag of > 10 degrees with preserved knee flexion and significant improvements in the mean Knee Society scores for pain and function

Background context. Fusion is a fundamental procedure in spine surgery. Although autogenous grafts have ideal bone graft characteristics, their use may remain limited due to various morbidities. Even though ceramic based synthetic bone grafts are used commonly at present, in order to enhance their efficacy, their combined use with other materials has been investigated. The use of carbon nanotubes (CNTs) together with synthetic bone grafts such as hydroxyapatite (HA) has contributed to positive developments in bone tissue engineering. Purpose. The aim of the present study was to investigate the effect of CNTs/ HA- tricalcium phosphate (TCP) composite prepared in posterolateral spinal fusion model. Study Design/Setting. Experimental animal study. Methods. At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Spraque Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later all animals were sacrificed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro computed tomography (mCT). Results. In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3). Although in Group 2, in which only CNTs were used, the ratio was found to be significantly higher than group 1, the difference was not considered significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e. no bone formation was observed. Conclusions. The combined use of carbon nanotubes with ceramic based bone grafts enhances spinal fusion markedly. Although CNTs are inadequate in producing spinal fusion when they are used by themselves, due to especially their high biocompatibillity and unique bicomechanic characteristics compatible with bone tissue, they increase fusion rates significantly, particularly together with ceramic based synthetic grafts. Keywords. Spinal fusion; Rat; Carbon nanotube(s); Ceramic(s); Bone graft subsitutes; Hydroxyapatite