Financial burden of anterior cruciate ligament reconstructions in football (soccer) players: an Australian cost of injury study.

OBJECTIVES: To estimate the financial burden of anterior cruciate ligament (ACL) reconstructions in amateur football (soccer) players in Australia over a single year, including both direct and indirect cost. METHODS: Available national direct and indirect cost data were applied to the annual incidence of ACL reconstructions in Australia. Age-adjusted and sex-adjusted total and mean costs (ACL and osteoarthritis (OA)) were calculated for amateur football (soccer) players in Australia using an incidence-based approach. RESULTS: The estimated cost of ACL reconstructions for amateur football players is $A69 623 211 with a mean total cost of $A34 079. The mean indirect costs are 19.8% higher than the mean direct costs. The mean indirect costs are lower in female (11.5%, $A28 628) and junior (15.3%, $A29 077) football players. The mean ACL costs are 3-4-fold greater than the mean OA costs ($A27 099 vs $A6450, respectively), remaining consistent when stratified by sex and age group. Our model suggests that for every 10% increase in adherence to injury prevention programmes, which equates to approximately 102 less ACL injuries per year, $A9 460 224 in ACL costs could be saved. CONCLUSION: While the number of ACL reconstructions per year among football players in Australia is relatively small, the annual financial burden is high. Our study suggests that if injury prevention exercises programmes are prioritised by stakeholders in football, significant cost-savings are possible.

Who Benefits From Allowing the Physis to Grow in Slipped Capital Femoral Epiphysis?

BACKGROUND: The globally acknowledged treatment for mild to moderate slipped capital femoral epiphysis (SCFE) is single screw in situ fixation, also used for prophylactic contralateral fixation. The Free-Gliding Screw (FG; Pega Medical) is a 2-part free-extending screw system designed to allow the growth of the proximal femur. We aimed to analyze the relationship between skeletal maturity and potential growth of the proximal physis and remodeling of the femoral neck using this implant. MATERIALS AND METHODS: Females below 12 years and males below 14 years undergoing in situ fixation for stable SCFE or prophylactic fixation were treated using the implant. Three elements of the modified Oxford Bone (mOB 3 ) score were used to measure maturity (triradiate cartilage, head of the femur, and greater trochanter). Radiographs were analyzed immediately postoperatively and at a minimum of 2 years for a change in screw length, posterior-sloping angle, articulotrochanteric distance, α angle, and head-neck offset. RESULTS: The study group comprised 30 (F:M=12:18) of 39 hips treated with SCFE and 22 (F:M=13:9) of 29 hips managed prophylactically using the free-Gliding screw. In the therapeutic group, chronologic age was a less valuable predictor of future screw lengthening than mOB 3 . An mOB 3 of ≤13 predicted future growth of >6 mm but did not reach statistical significance ( P =0.07). Patients with open triradiates showed a mean screw lengthening of 6.6 mm compared with those with closed triradiates (4.0 mm), but this did not reach significance ( P =0.12). In those with mOB 3 ≤13, the α angle reduced significantly ( P <0.01) and the head-neck offset increased significantly, suggesting remodeling. There was no change in these parameters when mOB 3 ≥14. In the prophylactic group, change in screw length was significant with mOB 3 of ≤13 (mean=8.0 mm, P <0.05), as was the presence of an open triradiate cartilage (mean=7.7 mm, P <0.05). In both cohorts, posterior-sloping angle and articulotrochanteric distance did not change, indicating no slip progression in either treatment or prophylactic groups and minimal effect on the proximal physeal growth relative to the greater trochanter. CONCLUSIONS: Growing screw constructs can halt slip progression while allowing proximal femoral growth in young patients with SCFE. Ongoing growth is better when the implant is used for prophylactic fixation. The results in treated SCFE need to be expanded to demonstrate a clinically meaningful cut-off for significant growth, but SCFE patients with an open triradiate remodel significantly more than those where it is closed. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Clinical applications of machine learning in predicting 3D shapes of the human body: a systematic review.

BACKGROUND: Predicting morphological changes to anatomical structures from 3D shapes such as blood vessels or appearance of the face is a growing interest to clinicians. Machine learning (ML) has had great success driving predictions in 2D, however, methods suitable for 3D shapes are unclear and the use cases unknown. OBJECTIVE AND METHODS: This systematic review aims to identify the clinical implementation of 3D shape prediction and ML workflows. Ovid-MEDLINE, Embase, Scopus and Web of Science were searched until 28th March 2022. RESULTS: 13,754 articles were identified, with 12 studies meeting final inclusion criteria. These studies involved prediction of the face, head, aorta, forearm, and breast, with most aiming to visualize shape changes after surgical interventions. ML algorithms identified were regressions (67%), artificial neural networks (25%), and principal component analysis (8%). Meta-analysis was not feasible due to the heterogeneity of the outcomes. CONCLUSION: 3D shape prediction is a nascent but growing area of research in medicine. This review revealed the feasibility of predicting 3D shapes using ML clinically, which could play an important role for clinician-patient visualization and communication. However, all studies were early phase and there were inconsistent language and reporting. Future work could develop guidelines for publication and promote open sharing of source code.

Effect of rapamycin on bone mass and strength in the α2(I)-G610C mouse model of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is commonly caused by heterozygous type I collagen structural mutations that disturb triple helix folding and integrity. This mutant-containing misfolded collagen accumulates in the endoplasmic reticulum (ER) and induces a form of ER stress associated with negative effects on osteoblast differentiation and maturation. Therapeutic induction of autophagy to degrade the mutant collagens could therefore be useful in ameliorating the ER stress and deleterious downstream consequences. To test this, we treated a mouse model of mild to moderate OI (α2(I) G610C) with dietary rapamycin from 3 to 8 weeks of age and effects on bone mass and mechanical properties were determined. OI bone mass and mechanics were, as previously reported, compromised compared to WT. While rapamycin treatment improved the trabecular parameters of WT and OI bones, the biomechanical deficits of OI bones were not rescued. Importantly, we show that rapamycin treatment suppressed the longitudinal and transverse growth of OI, but not WT, long bones. Our work demonstrates that dietary rapamycin offers no clinical benefit in this OI model and furthermore, the impact of rapamycin on OI bone growth could exacerbate the clinical consequences during periods of active bone growth in patients with OI caused by collagen misfolding mutations.

Inhibiting the osteocyte-specific protein sclerostin increases bone mass and fracture resistance in multiple myeloma.

Multiple myeloma (MM) is a plasma cell cancer that develops in the skeleton causing profound bone destruction and fractures. The bone disease is mediated by increased osteoclastic bone resorption and suppressed bone formation. Bisphosphonates used for treatment inhibit bone resorption and prevent bone loss but fail to influence bone formation and do not replace lost bone, so patients continue to fracture. Stimulating bone formation to increase bone mass and fracture resistance is a priority; however, targeting tumor-derived modulators of bone formation has had limited success. Sclerostin is an osteocyte-specific Wnt antagonist that inhibits bone formation. We hypothesized that inhibiting sclerostin would prevent development of bone disease and increase resistance to fracture in MM. Sclerostin was expressed in osteocytes from bones from naive and myeloma-bearing mice. In contrast, sclerostin was not expressed by plasma cells from 630 patients with myeloma or 54 myeloma cell lines. Mice injected with 5TGM1-eGFP, 5T2MM, or MM1.S myeloma cells demonstrated significant bone loss, which was associated with a decrease in fracture resistance in the vertebrae. Treatment with anti-sclerostin antibody increased osteoblast numbers and bone formation rate but did not inhibit bone resorption or reduce tumor burden. Treatment with anti-sclerostin antibody prevented myeloma-induced bone loss, reduced osteolytic bone lesions, and increased fracture resistance. Treatment with anti-sclerostin antibody and zoledronic acid combined increased bone mass and fracture resistance when compared with treatment with zoledronic acid alone. This study defines a therapeutic strategy superior to the current standard of care that will reduce fractures for patients with MM.

Bone Marrow Transplantation for Treatment of the Col1a2+/G610C Osteogenesis Imperfecta Mouse Model.

Bone marrow transplantation (BMT) of healthy donor cells has been postulated as a strategy for treating osteogenesis imperfecta (OI) and other bone fragility disorders. The effect of engraftment by tail vein injection and/or marrow ablation by 6 Gy whole body irradiation were tested in Col1a2+/G610C (OI) mice as a model of mild-moderate OI. Dual-emission X-ray absorptiometry, microCT, and 4-point bending were used to measure bone volume (BV), bone mineral density (BMD), and biomechanical strength. BV, BMD, and mechanical strength were reduced in OI mice compared to wild type (WT) controls. BMT with and without irradiation yielded no difference in BV and BMD outcomes for both OI and WT mice, at 3 weeks. Transplantation of OI cells into OI mice to test for paracrine effects of BMT also showed no difference with non-transplanted OI mice. In a parallel cell tracking study, donor marrow was taken from transgenic mice constitutively expressing tdTomato and transplanted into WT mice. Lineage tracking demonstrated that irradiation considerably enhanced engraftment of tdTomato+ cells. However, tdTomato+ cells predominantly expressed TRAP and not AP, indicating engrafted donor cells were chiefly from the hematopoietic lineages. These data show that whole marrow transplantation fails to rescue the bone phenotype of Col1a2+/G610C (OI) mice and that osteopoietic engraftment is not significantly enhanced by irradiation. These findings are highly relevant to modern approaches focused on the gene repair of patient cells ex vivo and their subsequent reintroduction into the osteopoietic compartment via the circulation.

Dkk1 KO Mice Treated with Sclerostin Antibody Have Additional Increases in Bone Volume.

Dickkopf-1 (DKK1) and sclerostin are antagonists of the Wnt/ß-catenin pathway and decreased expression of either results in increased bone formation and mass. As both affect the same signaling pathway, we aimed to elucidate the redundancy and/or compensation of sclerostin and DKK1. Weekly sclerostin antibody (Scl-Ab) was used to treat 9-week-old female Dkk1 KO (Dkk1-/-:Wnt3+/-) mice and compared to Scl-Ab-treated wild-type mice as well as vehicle-treated Dkk1 KO and wild-type animals. While Wnt3 heterozygote (Wnt3+/-) mice show no bone phenotype, Scl-Ab and vehicle-treated control groups of this genotype were included. Specimens were harvested after 3 weeks for microCT, bone histomorphometry, anti-sclerostin immunohistochemistry, and biomechanical testing. Scl-Ab enhanced bone anabolism in all treatment groups, but with synergistic enhancement seen in the cancellous compartment of Dkk1 KO mice (bone volume + 55% Dkk1 KO p < 0.01; + 22% wild type p < 0.05). Scl-Ab treatment produced less marked increases in cortical bone of the tibiae, with anabolic effects similar across genotypes. Mechanical testing confirmed that Scl-Ab improved strength across all genotypes; however, no enhancement was seen within Dkk1 KO mice. Dynamic bone labeling showed that Scl-Ab treatment was associated with increased bone formation, regardless of genotype. Immunohistochemical staining for sclerostin protein indicated no differences in the Dkk1 KO mice, indicating that the increased Wnt signaling associated with DKK1 deficiency was not compensated by upregulation of sclerostin protein. These data suggest complex interactions between Wnt signaling factors in bone, but critically illustrate synergy between DKK1 deficiency and Scl-Ab treatment. These data support the application of dual-targeted therapeutics in the modulation of bone anabolism.

Homozygous Dkk1 Knockout Mice Exhibit High Bone Mass Phenotype Due to Increased Bone Formation.

Wnt antagonist Dkk1 is a negative regulator of bone formation and Dkk1 +/- heterozygous mice display a high bone mass phenotype. Complete loss of Dkk1 function disrupts embryonic head development. Homozygous Dkk1 -/- mice that were heterozygous for Wnt3 loss of function mutation (termed Dkk1 KO) are viable and allowed studying the effects of homozygous inactivation of Dkk1 on bone formation. Dkk1 KO mice showed a high bone mass phenotype exceeding that of heterozygous mice as well as a high incidence of polydactyly and kinky tails. Whole body bone density was increased in the Dkk1 KO mice as shown by longitudinal dual-energy X-ray absorptiometry. MicroCT analysis of the distal femur revealed up to 3-fold increases in trabecular bone volume and up to 2-fold increases in the vertebrae, compared to wild type controls. Cortical bone was increased in both the tibiae and vertebrae, which correlated with increased strength in tibial 4-point bending and vertebral compression tests. Dynamic histomorphometry identified increased bone formation as the mechanism underlying the high bone mass phenotype in Dkk1 KO mice, with no changes in bone resorption. Mice featuring only Wnt3 heterozygosity showed no evident bone phenotype. Our findings highlight a critical role for Dkk1 in the regulation of bone formation and a gene dose-dependent response to loss of DKK1 function. Targeting Dkk1 to enhance bone formation offers therapeutic potential for osteoporosis.

CSA-90 Promotes Bone Formation and Mitigates Methicillin-resistant Staphylococcus aureus Infection in a Rat Open Fracture Model.

BACKGROUND: Infection of open fractures remains a significant cause of morbidity and mortality to patients worldwide. Early administration of prophylactic antibiotics is known to improve outcomes; however, increasing concern regarding antimicrobial resistance makes finding new compounds for use in such cases a pressing area for further research. CSA-90, a synthetic peptidomimetic compound, has previously demonstrated promising antimicrobial action against Staphylococcus aureus in rat open fractures. However, its efficacy against antibiotic-resistant microorganisms, its potential as a therapeutic agent in addition to its prophylactic effects, and its proosteogenic properties all require further investigation. QUESTIONS/PURPOSES: (1) Does prophylactic treatment with CSA-90 reduce infection rates in a rat open fracture model inoculated with S aureus, methicillin-resistant S aureus (MRSA), and methicillin-resistant Staphylococcus epidermidis (MRSE) as measured by survival, radiographic union, and deep tissue swab cultures? (2) Does CSA-90 reduce infection rates when administered later in the management of an open fracture as measured by survival, radiographic union, and deep tissue swab cultures? (3) Does CSA-90 demonstrate a synergistic proosteogenic effect with bone morphogenetic protein 2 (BMP-2) in a noninfected rat ectopic bone formation assay as assessed by micro-CT bone volume measurement? (4) Can CSA-90 elute and retain its antimicrobial efficacy in vitro when delivered using clinically relevant agents measured using a Kirby-Bauer disc diffusion assay? METHODS: All in vivo studies were approved by the local animal ethics committee. In the open fracture studies, 12-week-old male Wistar rats underwent open midshaft femoral fractures stabilized with a 1.1-mm Kirschner wire and 10 µg BMP-2 ± 500 µg CSA-90 was applied to the fracture site using a collagen sponge along with 1 x 10 colony-forming units of bacteria (S aureus/MRSA/MRSE; n = 10 per group). In the delayed treatment study, débridement and treatment with 500 µg CSA-90 were performed at Day 1 and Day 5 after injury and bacterial insult (S aureus). All animals were reviewed daily for signs of local infection and/or sepsis. An independent, blinded veterinarian reviewed twice-weekly radiographs, and rats showing osteolysis and/or declining overall health were culled at his instruction. The primary outcome of both fracture studies was fracture infection, incorporating survival, radiographic union, and deep tissue swab cultures. For the ectopic bone formation assay, 0 to 10 µg BMP-2 and 0 to 500 µg CSA-90 were delivered on a collagen sponge into bilateral quadriceps muscle pouches of 8-week-old rats (n = 10 per group). Micro-CT quantification of bone volume and descriptive histologic analysis were performed for all in vivo studies. Modified Kirby-Bauer disc diffusion assays were used to quantify antimicrobial activity in vitro using four different delivery methods, including bone cement. RESULTS: Infection was observed in none of the MRSA inoculated open fractures treated with CSA-90 with 10 of 10 deep tissue swab cultures negative at the time of cull. Median survival was 43 days (range, 11-43 days) in the treated group versus 11 days (range, 8-11 days) in the untreated MRSA inoculated group (p < 0.001). However, delayed débridement and treatment of open fractures with CSA-90 at either Day 1 or Day 5 did not prevent infection, resulting in early culls by Day 21 with positive swab cultures (10 of 10 for each time point). Maximal ectopic bone formation was achieved with 500 µg CSA-90 and 10 µg BMP-2 (mean volume, 9.58 mm; SD, 7.83), creating larger bone nodules than formed with 250 µg CSA-90 and 10 µg BMP-2 (mean volume, 1.7 mm; SD, 1.07; p < 0.001). Disc diffusion assays showed that CSA-90 could successfully elute from four potential delivery agents including calcium sulphate (mean zone of inhibition, 11.35 mm; SD, 0.957) and bone cement (mean, 4.67 mm; SD, 0.516). CONCLUSIONS: CSA-90 shows antimicrobial action against antibiotic-resistant Staphylococcal strains in vitro and in an in vivo model of open fracture infection. CLINICAL RELEVANCE: The antimicrobial properties of CSA-90 combined with further evidence of its proosteogenic potential make it a promising compound to develop further for orthopaedic applications.

Sclerostin Antibody Increases Callus Size and Strength but does not Improve Fracture Union in a Challenged Open Rat Fracture Model.

Open fractures remain a challenge in orthopedics. Current strategies to intervene are often inadequate, particularly in severe fractures or when treatment is delayed. Sclerostin is a negative regulator of bone growth and sclerostin-neutralizing antibodies (Scl-Ab) can increase bone mass and strength. The application of these antibodies to improve orthopedic repair has shown varied results, and may be dependent on the location and severity of the bony injury. We examined Scl-Ab treatment within an established rat osteotomy model with periosteal stripping analogous to open fracture repair. In one study, Scl-Ab was given 25 mg/kg bi-weekly, either from the time of fracture or from 3 weeks post-fracture up to an end-point of 12 weeks. A second study treated only delayed union open fractures that did not show radiographic union by week 6 post-fracture. Outcome measures included radiographic union, microCT analysis of bone volume and architecture, and histology. In the first study, Scl-Ab given from either 0 or 3 weeks significantly improved callus bone volume (+52%, p < 0.05 and +58%, p < 0.01) at 12 weeks, as well as strength (+48%, p < 0.05 and +70%, p < 0.05). Despite these improvements, union rate was not changed. In the second study treating only established delayed fractures, bony callus volume was similarly increased by Scl-Ab treatment; however, this did not translate to increased biomechanical strength or union improvement. Sclerostin antibody treatment has limited effects on the healing of challenging open fractures with periosteal stripping, but shows the greatest benefits on callus size and strength with earlier intervention.

Fabrication of a Biodegradable Implant with Tunable Characteristics for Bone Implant Applications.

Biodegradable polymers are appealing material for the manufacturing of surgical implants as such implants break down in vivo, negating the need for a subsequent operation for removal. Many biocompatible polymers produce acidic breakdown products that can lead to localized inflammation and osteolysis. This study assesses the feasibility of fabricating implants out of poly(propylene carbonate) (PPC)-starch that degrades into CO2 and water. The basic compression modulus of PPC-starch (1:1 w/w) is 34 MPa; however, the addition of glycerol (1% w/w) and water as plasticizers doubles this value and enhances the surface wettability. The bioactivity and stiffness of PPC-starch blends is increased by the addition of bioglass microparticles (10% w/w) as shown by in vitro osteoblast differentiation assay and mechanical testing. MicroCT analysis confirms that the bioglass microparticles are evenly distributed throughout biomaterial. PPC-starch-bioglass was tested in vivo in two animal models. A murine subcutaneous pellet degradation assay demonstrates that the PPC-starch-bioglass blend's volume fraction loss is 46% after 6 months postsurgery, while it is 27% for poly(lactic acid). In a rat knee implantation model, PPC-starch-bioglass screws inserted into the distal femur show osseointegration with no localized adverse effects after 3 and 12 weeks. These data support the further development of PPC-starch-bioglass as a medical biomaterial.

Local delivery of recombinant human bone morphogenetic proteins and bisphosphonate via sucrose acetate isobutyrate can prevent femoral head collapse in Legg-Calve-Perthes disease: a pilot study in pigs.

PURPOSE: Legg-Calve-Perthes disease is a paediatric condition encompassing idiopathic osteonecrosis of the femoral head (ONFH). Preventing collapse and the need for subsequent joint replacement remains the major goal of clinical management. This exploratory study utilises a porcine model of surgically induced ONFH. METHODS: rhBMP-2 with and without zoledronic acid (ZA) was delivered by intra-osseous injection in the phase-transitioning sucrose acetate isobutyrate (SAIB) in an attempt to prevent femoral head collapse. Epiphyseal quotient (EQ) at eight weeks post-surgery was the primary outcome measure. Heterotopic ossification in the joint capsule and bisphosphonate retention in the femoral head were key secondary outcomes. RESULTS: Femoral heads with ONFH and no treatment all collapsed (3/3, EQ < 0.4, P < 0.05 compared to no ONFH). Local delivery of rhBMP-2/SAIB into the femoral head prevented collapse by EQ measurement one of four samples; however, this specimen still showed evidence of significant collapse. In contrast, the combination of local rhBMP-2 and local ZA prevented collapse in two of four samples. Confocal fluorescence microscopy showed locally dosed bisphosphonate entered and was retained in the femoral head. This group also showed strong Calcein signal, indicating new bone formation. Treatment with rhBMP-2 was associated with a limited amount of heterotrophic ossification in the joint capsules in some specimens. CONCLUSIONS: Operators reported SAIB to be an efficient way to deliver rhBMP-2 to the femoral head. These data suggest that rhBMP-2 is ineffective for preventing femoral head collapse without the addition of bisphosphonate. Further research will be required to validate the clinical efficacy of a combined local rhBMP-2/bisphosphonate approach.

Comparison of accuracy and speed between plaster casting, high-cost and low-cost 3D scanners to capture foot, ankle and lower leg morphology of children requiring ankle-foot orthoses.

BACKGROUND: Traditional plaster-cast fabrication of an ankle-foot orthosis (AFO), although robust, is time-consuming and cumbersome. 3D scanning is quickly gaining attention as an alternative to plaster casting the foot and ankle region for AFO fabrication. The aim of this study was to assess the accuracy and speed of two high-performing 3D scanners compared with plaster casting in pediatric patients requiring an AFO. METHODS: Ten participants (mean age 10.0 ± 3.9 years) prescribed AFOs for a movement disorder were 3D scanned with the high-cost Artec Eva (Eva) and low-cost Structure Sensor II (SSII) using one-person (1p) and two-person (2p) protocols. Accuracy and speed for both 3D scanners were compared with corresponding plaster cast measures (≤5% acceptable difference). Bland and Altman plots were generated to show mean bias and limits of agreement. RESULTS: Overall, Eva and SSII were accurate for foot, ankle, and lower leg key clinical landmarks (Eva-1p: 4.4 ± 7.3%; Eva-2p: 3.2 ± 7.5%; SSII-1p: 0.6 ± 7.4%; SSII-2p: 0.7 ± 8.2%). Bland and Altman plots for the SSII demonstrated lower biases for 1p (bias 0.5 mm, LoA: -12.4-13.5 mm) and 2p (0.4 mm, LoA: -11.4-12.2 mm) protocols compared with Eva for 1p (bias 2.3 mm, LoA: -8.0-12.7 mm) and 2p (1.8 mm, LoA: -10.7-14.3 mm) protocols. The SSII 2p protocol was the fastest 3D scanning method (26.4 ± 11.1 s). CONCLUSIONS: The high-cost Eva and low-cost SSII 3D scanners using the 1p and 2p protocols produced comparable accuracy and faster capture of key clinical landmarks compared with plaster cast measures for the fabrication of AFOs in pediatric patients.

Comparison of multiple 3D scanners to capture foot, ankle, and lower leg morphology.

BACKGROUND: 3D scanning of the foot and ankle is gaining popularity as an alternative method to traditional plaster casting to fabricate ankle-foot orthoses (AFOs). However, comparisons between different types of 3D scanners are limited. OBJECTIVES: The aim of this study was to evaluate the accuracy and speed of seven 3D scanners to capture foot, ankle, and lower leg morphology to fabricate AFOs. STUDY DESIGN: Repeated-measures design. METHODS: The lower leg region of 10 healthy participants (mean age 27.8 years, standard deviation [SD] 9.3) was assessed with 7 different 3D scanners: Artec Eva (Eva), Structure Sensor (SS I), Structure Sensor Mark II (SS II), Sense 3D Scanner (Sense), Vorum Spectra (Spectra), Trnio 3D Scanner App on iPhone 11 (Trnio 11), and Trnio 3D Scanner App on iPhone 12 (Trnio 12). The reliability of the measurement protocol was confirmed initially. The accuracy was calculated by comparing the digital scan with clinical measures. A percentage difference of #5% was considered acceptable. Bland and Altman plots were used to show the mean bias and limit of agreement (LoA) for each 3D scanner. Speed was the time needed for 1 complete scan. RESULTS: The mean accuracy ranged from 6.4% (SD 10.0) to 230.8% (SD 8.4), with the SS I (21.1%, SD 6.8), SS II (21.7%, SD 7.5), and Eva (2.5%, SD 4.5) within an acceptable range. Similarly, Bland and Altman plots for Eva, SS I, and SS II showed the smallest mean bias and LoA 21.7 mm (LoA 25.8 to 9.3), 21.0 mm (LoA 210.3 to 8.3), and 0.7 mm (LoA 213 to 11.5), respectively. The mean speed of the 3D scanners ranged from 20.8 seconds (SD 8.1, SS I) to 329.6 seconds (SD 200.2, Spectra). CONCLUSIONS: Eva, SS I, and SS II appear to be the most accurate and fastest 3D scanners for capturing foot, ankle, and lower leg morphology, which could be used for AFO fabrication.

Targeted postnatal knockout of Sclerostin using a bone-targeted adeno-associated viral vector increases bone anabolism and decreases canalicular density.

PURPOSE: The creation of murine gene knockout models to study bone gene functions often requires the resource intensive crossbreeding of Cre transgenic and gene-floxed strains. The developmental versus postnatal roles of genes can be difficult to discern in such models. For example, embryonic deletion of the Sclerostin (Sost) gene establishes a high-bone mass phenotype in neonatal mice that may impact on future bone growth. To generate a postnatal skeletal knockout of Sost in adult mice, this study used a single injection of a bone-targeted recombinant adeno-associated virus (rAAV) vector. METHODS: 8-week-old Sostflox/flox mice were injected with saline (control) or a single injection containing 5 × 1011 vg AAV8-Sp7-Cre vector. Ai9 fluorescent Cre reporter mice were dosed in parallel to confirm targeting efficiency. After 6 weeks, detailed bone analysis was performed via microCT, biomechanical testing, and bone histology on vertebral and long bone specimens. RESULTS: The AAV8-Sp7-Cre vector induced widespread persistent recombination in the bone compartment. Regional microCT analyses revealed significant increases in bone with vector treatment. In the L3 vertebrae, Sostflox/flox:AAV-Cre showed a 22 % increase in bone volume and 21 % in trabecular bone fraction compared to controls; this translated to a 17 % increase in compressive strength. In the tibiae, Sostflox/flox:AAV-Cre led to small but statistically significant increases in cortical bone volume and thickness. These were consistent with a 25 % increase in mineral apposition rate, but this did not translate into increased four-point bending strength. Ploton silver nitrate stain on histological sections revealed an unexpected increase in canalicular density associated with Sost ablation. CONCLUSION: This report demonstrates a proof-of-concept that the AAV8-Sp7-Cre vector can efficiently produce postnatal skeletal knockout mice using gene-floxed strains. This technology has the potential for broad utility in the bone field with existing conditional lines. These data also confirm an important postnatal role for Sost in regulating bone homeostasis, consistent with prior studies using neutralizing Sclerostin antibodies, and highlights a novel role of Sost in canalicular remodeling.

Multi-Targeting DKK1 and LRP6 Prevents Bone Loss and Improves Fracture Resistance in Multiple Myeloma.

An imbalance between bone resorption and bone formation underlies the devastating osteolytic lesions and subsequent fractures seen in more than 90% of multiple myeloma (MM) patients. Currently, Wnt-targeted therapeutic agents that prevent soluble antagonists of the Wnt signaling pathway, sclerostin (SOST) and dickkopf-1 (DKK1), have been shown to prevent bone loss and improve bone strength in preclinical models of MM. In this study, we show increasing Wnt signaling via a novel anti-low-density lipoprotein receptor-related protein 6 (LRP6) antibody, which potentiates Wnt1-class ligand signaling through binding the Wnt receptor LRP6, prevented the development of myeloma-induced bone loss primarily through preventing bone resorption. When combined with an agent targeting the soluble Wnt antagonist DKK1, we showed more robust improvements in bone structure than anti-LRP6 treatment alone. Micro-computed tomography (µCT) analysis demonstrated substantial increases in trabecular bone volume in naïve mice given the anti-LRP6/DKK1 combination treatment strategy compared to control agents. Mice injected with 5TGM1eGFP murine myeloma cells had significant reductions in trabecular bone volume compared to naïve controls. The anti-LRP6/DKK1 combination strategy significantly improved bone volume in 5TGM1-bearing mice by 111%, which was also superior to anti-LRP6 single treatment; with similar bone structural changes observed within L4 lumbar vertebrae. Consequently, this combination strategy significantly improved resistance to fracture in lumbar vertebrae in 5TGM1-bearing mice compared to their controls, providing greater protection against fracture compared to anti-LRP6 antibody alone. Interestingly, these improvements in bone volume were primarily due to reduced bone resorption, with significant reductions in osteoclast numbers and osteoclast surface per bone surface demonstrated in 5TGM1-bearing mice treated with the anti-LRP6/DKK1 combination strategy. Importantly, Wnt stimulation with either single or combined Wnt-targeted agents did not exacerbate tumor activity. This work provides a novel approach of targeting both membrane-bound and soluble Wnt pathway components to provide superior skeletal outcomes in patients with multiple myeloma and other bone destructive cancers. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

An Opportunity to See the Heart Defect Physically: Medical Student Experiences of Technology-Enhanced Learning with 3D Printed Models of Congenital Heart Disease.

Three-dimensional (3D) printing is increasingly used in medical education and paediatric cardiology. A technology-enhanced learning (TEL) module was designed to accompany 3D printed models of congenital heart disease (CHD) to aid in the teaching of medical students. There are few studies evaluating the attitudes and perceptions of medical students regarding their experience of learning about CHD using 3D printing. This study aimed to explore senior medical students' experiences in learning about paediatric cardiology through a workshop involving 3D printed models of CHD supported by TEL in the form of online case-based learning. A mixed-methods evaluation was undertaken involving a post-workshop questionnaire (n = 94 students), and focus groups (n = 16 students). Focus group and free-text questionnaire responses underwent thematic analysis. Questionnaire responses demonstrated widespread user satisfaction; 91 (97%) students agreed that the workshop was a valuable experience. The highest-level satisfaction was for the physical 3D printed models, the clinical case-based learning, and opportunity for peer collaboration. Thematic analysis identified five key themes: a variable experience of prior learning, interplay between physical and online models, flexible and novel workshop structure, workshop supported the learning outcomes, and future opportunities for learning using 3D printing. A key novel finding was that students indicated the module increased their confidence to teach others about CHD and recommended expansion to other parts of the curriculum. 3D printed models of CHD are a valuable learning resource and contribute to the richness and enjoyment of medical student learning, with widespread satisfaction. Supplementary Information: The online version contains supplementary material available at 10.1007/s40670-023-01840-w.

Utility of 3D Printed Models Versus Cadaveric Pathology for Learning: Challenging Stated Preferences.

Introduction: 3D printing has recently emerged as an alternative to cadaveric models in medical education. A growing body of research supports the use of 3D printing in this context and details the beneficial educational outcomes. Prevailing studies rely on participants' stated preferences, but little is known about actual student preferences. Methods: A mixed methods approach, consisting of structured observation and computer vision, was used to investigate medical students' preferences and handling patterns when using 3D printed versus cadaveric models in a cardiac pathology practical skills workshop. Participants were presented with cadaveric samples and 3D printed replicas of congenital heart deformities. Results: Analysis with computer vision found that students held cadaveric hearts for longer than 3D printed models (7.71 vs. 6.73 h), but this was not significant when comparing across the four workshops. Structured observation found that student preferences changed over the workshop, shifting from 3D printed to cadaveric over time. Interactions with the heart models (e.g., pipecleaners) were comparable. Conclusion: We found that students had a slight preference for cadaveric hearts over 3D printed hearts. Notably, our study contrasts with other studies that report student preferences for 3D printed learning materials. Given the relative equivalence of the models, there is opportunity to leverage 3D printed learning materials (which are not scarce, unlike cadaveric materials) to provide equitable educational opportunities (e.g., in rural settings, where access to cadaveric hearts is less likely).

Replicating and redesigning ankle-foot orthoses with 3D printing for children with Charcot-Marie-Tooth disease.

BACKGROUND: Children with the most common inherited neuropathy, Charcot-Marie-Tooth disease (CMT), are often prescribed ankle-foot orthoses (AFOs) to improve walking ability and prevent falls by reducing foot drop, postural instability, and other gait impairments. These externally worn assistive devices are traditionally custom-made using thermoplastic vacuum forming. This labour-intensive manufacturing process often results in AFOs which are cumbersome due to limited design options, and are associated with low acceptability, discomfort, and suboptimal impact on gait. The aim of this study was to determine how 3D printing can be used to replicate and redesign AFOs in children with CMT. METHODS: Traditional AFOs, 3D printed replica AFOs (same design as traditional AFOs), 3D printed redesigned AFOs and a shoes only control condition were compared in 12 children with CMT. 3D printed AFOs were manufactured using material extrusion in Nylon-12. 3D gait analysis (temporal-spatial, kinematic, kinetic), in-shoe pedobarography and self-reported satisfaction were used to compare conditions. The primary kinematic and kinetic outcome measures were maximum ankle dorsiflexion in swing and maximum ankle dorsiflexor moment in loading response, to capture foot drop and an absent of heel rocker. RESULTS: The 3D printed replica AFOs were comparable to traditional AFOs for all outcomes. The 3D printed replica AFOs improved foot position at initial contact and during loading response and significantly reduced pressure beneath the whole foot, rearfoot and forefoot compared to the shoes only. The 3D printed redesigned AFOs produced a device that was significantly lighter (mean -35.2, SD 13.3%), and normalised maximum ankle dorsiflexor moment in loading response compared to shoes only and traditional AFOs. SIGNIFICANCE: 3D printing can be used to replicate traditional handmade AFOs and to redesign AFOs to produce a lighter device with improved biomechanics by incorporating novel design features.

Combination treatment with growth hormone and zoledronic acid in a mouse model of Osteogenesis imperfecta.

INTRODUCTION: Osteogenesis imperfecta (OI) or brittle bone disease is a genetic disorder that results in bone fragility. Bisphosphonates such as zoledronic acid (ZA) are used clinically to increase bone mass and reduce fracture risk. Human growth hormone (hGH) has been used to promote long bone growth and forestall short stature in children with OI. The potential for hGH to improve bone quality, particularly in combination with ZA has not been robustly studied. METHODS: A preclinical study was performed using n = 80 mice split evenly by genotype (WT, Col1a2+/G610C). Groups of n = 10 were treated with +/-ZA and +/-hGH in a factorial design for each genotype. Outcome measures included bone length, isolated muscle mass, bone parameters assessed by microCT analysis, dynamic histomorphometry, and biomechanical testing. RESULTS: Treatment with hGH alone led to an increase in femur length in WT but not OI mice, however bone length was increased in both genotypes with the combination of hGH/ZA. MicroCT showed that hGH/ZA treatment increased cortical BV in both WT (+15%) and OI mice (+14.3%); hGH/ZA were also found to be synergistic in promoting cortical thickness in OI bone. ZA was found to have a considerably greater positive impact on trabecular bone than hGH. ZA was found to suppress bone turnover, and this was rescued by hGH treatment in terms of cortical periosteal perimeter, but not by dynamic bone remodeling. Statistically significant improvements in long bone by microCT did not translate into improvements in mechanical strength in a 4-point bending test, nor did vertebral strength improve in L4 compression testing in WT/OI bone. DISCUSSION/CONCLUSION: These data support hGH/ZA combination as a treatment for short stature, however the improvements granted by hGH alone and in combination with ZA on bone quality are modest. Increased periosteal perimeter does show promise in improving bone strength in OI, however a longer treatment time may be required to see effects on bone strength through mechanical testing.