There is an established link between bone quality and fracture risk. It has been suggested that reduced bone quality will also reduce the toughening mechanisms displayed during loading at a high strain rate. We hypothesised that partially decalcified bone will not demonstrate an increase in force required to cause failure when comparing low and high strain rate loading. Mechanical properties were defined by the maximum force at failure. Bone quality was defined by the mineral content. This was altered by subjecting the bones to ultrasonically assisted decalcification in 10M EDTA to achieve an average 18% mineral reduction (A 70 yr old woman has approx 18% of her peak bone mass). 20 pairs of sheep femurs were harvested and split into four equal groups: normal bone quality, fast strain rate (NF); normal bone quality, slow strain rate (NS); low bone quality, fast strain rate (LF) and low bone quality, slow strain rate (LS). All mechanical testing was carried out by means of 3-point bending. Load representing the slow strain rate was applied by a mechanical testing machine (Zwick) at a rate resulting in a deflection of 1mm/s. The dynamic loading was applied by a custom designed pneumatic ram at a mean rate of deflection between the specimens of 2983 mm/s (±SD 1155), this equates to strain rates experienced in a road traffic accident. The following results for force at failure were found (mean ± SD). NF: Force 5503N (± 1012); NS: Force 3969N (± 572); LF: Force 3485N (± 772); LS: Force 3165N (± 605). Groups were compared using a Mann-Whitney U test. Significant results were found between the following groups: Normal bone quality, strain rate compared (NF-NS) p<0.002; Fast strain rate, bone quality compared (NF-LF) p=0.008; Slow strain rate, bone quality compared (NS-LS) p=0.02. No statistical significance was found when comparing low bone quality, strain rate compared (LF-LS) p=0.47. These results show that normal healthy bone has an ability to withstand higher strain rates which protects it against fracture. This ability to withstand high strain rates is lost in decalcified bone making it more susceptible to fracture. The results of this study indicate the importance of strain rate reduction as well as energy absorption in the design of hip protectors and in environmental modifications

As a part of the European Union BIOMED I study “Assessment of Bone Quality in Osteoporosis,” Sixty-nine second lumbar vertebral body specimens (L2) were obtained post mortem from 32 women and 37 men (age 24–92 years). Our initial remit was to study variations in density of the calcified tissues by quantitative backscattered electron imaging (BSE-SEM). To this end, the para-sagittal bone slices were embedded in PMMA and block surfaces micro-milled and carbon coated. Many samples were re-polished to remove the carbon coat and stained with iodine vapour to permit simultaneous BSE imaging of non-mineralised tissues - especially disc, annulus, cartilage and ligament - uncoated, at 50Pa chamber pressure. We have now studied most of these samples by 30-μm resolution high contrast resolution X-ray microtomography (XMT), typically 72 hours scanning time, thus giving exact correlation between high resolution BSE-SEM and XMT. The 3D XMT data sets were rendered using Drishti software to produce static and movie images for visualisation and edification. We have now selected a set of the female samples for reconstruction by 3D printing - taking as examples the youngest, post-menopausal, oldest, best, worst, and anterior and central compression fractures and anterior collapse with fusion to L3 - which will be attached to the poster display. The most porotic cases were also the most difficult to reconstruct. A surprising proportion of elderly samples showed excellent bone architecture, though with retention of fewer, but more massive, load-bearing trabeculae

Abstract

Bone turnover and microdamage are impacted by skeletal metastases which can contribute to increased fracture risk. Treatments for metastatic disease may further impact bone quality. This study aimed to establish an understanding of microdamage accumulation and load to failure in healthy and osteolytic vertebrae following cancer treatment (stereotactic body radiotherapy (SBRT), zoledronic acid (ZA), or docetaxel (DTX)). Forty-two 6-week old athymic female rats (Hsd:RH-Foxn1rnu, Envigo) were studied; 22 were inoculated with HeLa cervical cancer cells through intracardiac injection (day 0). Animals were randomly assigned to four groups: untreated (healthy=5, osteolytic=6), SBRT on day 14 (healthy=6, osteolytic=6), ZA on day 7 (healthy=4, osteolytic=5), and DTX on day 14 (healthy=5, osteolytic=5). Animals were euthanized on day 21. L1-L3 motion segments were compression loaded to failure and force-displacement data recorded. T13 vertebrae were stained with BaSO. 4. and µCT imaged (90kVp, 44uA, 4.9µm) to visualize microdamage location and volume. Damage volume fraction (DV/BV) was calculated as the ratio of BaSO. 4. to bone volume. Differences in mean load-to-failure were compared using three-way ANOVA (disease status, treatment, cells injected). Differences in mean DV/BV between treatment groups were compared using one-way ANOVA. Treatment had a significant effect on load-to-failure (p=0.004) with ZA strengthening the healthy and osteolytic vertebrae. Reduced strength post SBRT seen in the metastatic (but not the healthy) group may be explained by greater tumor involvement secondary to higher cell injection concentrations. Untreated metastatic samples had higher DV/BV (16.25±2.54%) compared to all treatment groups (p<0.05) suggesting a benefit of treatment to bone quality. Focal and systemic cancer treatments were shown to effect load-to-failure and microdamage accumulation in healthy and osteolytic vertebrae. Developing a better understanding of how treatments effect bone quality and mechanical stability is critical for effective management of patients with spinal metastases

With an aging population and increase in total knee arthroplasty, periprosthetic distal femur fractures (PDFFs) have increased. The differences between these fractures and native distal femur fractures (NDFF) have not been comprehensively investigated. The purpose of this study was to compare the demographic, fracture, and treatment details of PDFFs compared to NDFFs. A retrospective study of patients ≥ 18 years old who underwent surgical treatment for either a NDFF or a PDFF from 2010 to 2020 at a level 1 trauma center was performed. Demographics, AO/OTA fracture classification, quality of reduction, fixation constructs, and unplanned revision reoperation were compared between PDFF patients and NDFF patients using t-test and Fisher's exact test. 209 patients were identified with 70 patients having a PDFF and 139 patients having a NDFF. Of note, 48% of NDFF had a concomitant fracture of the ipsilateral knee (14%) or tibial plateau (15%). The most common AO/OTA classification for PDFFs was 33A3.3 (71%). NDFFs had two main AO/OTA classifications of 33C2.2 (28%) or 33A3.2. (25%). When controlling for patient age, bone quality, fracture classification, and fixation, the PDFF group had increased revision reoperation rate compared to NDFF (P < 0.05). PDFFs tend to occur in elderly patients with low bone quality, have complete metaphyseal comminution, and be isolated; whereas, NDFF tend to occur in younger patients, have less metaphyseal comminution, and be associated with other fractures. When controlling for variables, PDFF are at increased risk of unplanned revision reoperation. Surgeons should be aware of these increased risks in PDFFs and future research should focus on these unique fracture characteristics to improve outcomes

There is no optimal therapy to stop or cure chondral degeneration in osteoarthritis (OA). Beside cartilage, subchondral bone is involved. The often sclerotic bone is mechanically less solid which in turn influences negatively chondral quality. Microfracturing as therapeutic technique aims to enhance bone quality but is applied only in smaller cartilage lesions. The osteoproliferative properties of Magnesium (Mg) have been shown repeatedly. 1-3. The present study examined the influence of micro-scaled Mg cylinders compared to sole drilling in an OA model. Ten New Zealand White rabbits underwent anterior crucial ligament transection. During 12 weeks after surgery, the animals developed OA as previously described. 4. In a second surgery, half of the animals received 20 drill holes (ø 0.5mm) and the other half received 20 drill holes, which were additionally filled with one Mg cylinder each. Extracapsular plication was performed in all animals. During the follow-up of 8 weeks three µ-computed tomographic (µCT) scans were performed: immediately after surgery and after four and eight weeks. Changes of bone volume, trabecular thickness and bone density were calculated and compared. µCT evaluation showed an increase in bone volume and trabecular thickness in both groups. This increase was significantly higher in rabbits which received Mg cylinders showing thrice as high values for both parameters (bone volume: Mg group +44.5%, drilling group +15.1%, p≤0.025; trabecular thickness: Mg group +53.2%, drilling group +16.9%, p≤0.025). Also bone density increased in both groups, but on a distinctly lower level and with no significant difference. Although profound higher bone volume was found after implantation of Mg cylinders, µCT showed similar levels of bone density indicating adequate bone quality in this OA model. Macroscopic and histological evaluation of cartilage condition have to reveal possible impact on OA progression. Additionally, current examination implement different alloys and influence on lameness

Spinal diseases such as unstable fractures, infections, primary or secondary tumors or deformities require surgical stabilization with implants. The long-term success of this treatment is only ensured by a solid bony fusion. The size of the bony defect, the often poor bone quality and metabolic diseases increase the risk of non-union and make the case a great burden for the patient and a challenge for the surgeon. The goal of spinal fusion can only be achieved if the implants used offer sufficient mechanical stability and the local biological regeneration potential is large enough to form sufficient bone. The lecture will present challenging clinical cases. In addition, implant materials and new surgical techniques are discussed. Local therapeutic effects are achieved through the release of osteopromotive or anti-resorbtive drugs, growth factors and antibiotics. By influencing biological pathways, basic orthopedic research has strong potential to further positively change future spinal surgery

Type-2 Diabetic (T2D) patients experience up to a 3-fold increase in bone fracture risk[1]. Paradoxically, T2D-patients have a normal or increased bone mineral density when compared to non-diabetic patients. This implies that T2D has a deleterious effect on bone quality, whereby the intrinsic material properties of the bone matrix are altered. Creating clinical challenges as current diagnostic techniques are unable to accurately predict the fracture probability in T2D-patients. To date, the relationship between cyclic fatigue loading, mechanical properties and microdamage accumulation of T2D-bone tissue has not yet been examined and thus our objective is to investigate this relationship. Ethically approved femoral heads were obtained from patients, with (n=8) and without (n=8) T2D. To obtain the mechanical properties of the sample, one core underwent a monotonic compression test to 10% strain, the other core underwent a cyclic compression test at a normalized stress ratio between 0.0035mm/mm and 0.016mm/mm to a maximum strain of 3%. Microdamage was evaluated by staining the tissue with barium sulfate precipitate [2] and conducting microcomputed tomography scanning with a voxel size of 10μm. The monotonically tested T2D-group showed no statistical difference in mechanical properties to the non-T2D-group, even when normalised against BV/TV. There was also no difference in BV/TV. For the cyclic test, the T2D-group had a significantly higher initial modulus (p<0.01) and final modulus (p<0.05). There was no difference in microdamage accumulation. Previous population-level studies have found that T2D-patients have been shown to have an increased fracture risk when compared to non-T2D-patients. This research indicates that T2D does not impair the mechanical properties of trabecular bone from the femoral heads of T2D-patients, suggesting that other mechanisms may be responsible for the increased fracture risk seen in T2D-patients

Majority of osteoporosis related fractures are treated surgically using metallic fixation devices. Anchorage of fixation devices is sometimes challenging due to poor osteoporotic bone quality that can lead to failure of the fracture fixation. Using a rat osteoporosis model, we employed neutron tomography and histology to study the biological effects of implant augmentation using an isothermally setting calcium sulphate/hydroxyapatite (CaS/HA) biomaterial with synthetic HA particles as recruiting moiety for systemically administered bisphosphonates. Using an osteoporotic sawbones model, we then provide a standardized method for the delivery of the CaS/HA biomaterial at the bone-implant interface for improved mechanical anchorage of a lag-screw commonly used for hip fracture fixation. As a proof-of-concept, the method was then verified in donated femoral heads and in patients with osteoporosis undergoing hip fracture fixation. We show that placing HA particles around a stainless-steel screw in-vivo, systemically administered bisphosphonates could be targeted towards the implant, yielding significantly higher peri-implant bone formation compared to un-augmented controls. In the sawbones model, CaS/HA based lag-screw augmentation led to significant increase (up to 4 times) in peak extraction force with CaS/HA performing at par with PMMA. Micro-CT imaging of the CaS/HA augmented lag-screws in cadaver femoral heads verified that the entire length of the lag-screw threads and the surrounding bone was covered with the CaS/HA material. X-ray images from fracture fixation surgery indicated that the CaS/HA material could be applied at the lag-screw-bone interface without exerting any additional pressure or risk of venous vascular leakage.: We present a new method for augmentation of lag-screws in fragile bone. It is envisaged that this methodcould potentially reduce the risk of fracture fixation failure especially when HA seeking “bone active” drugs are used systemically

Odontoid fracture of the second cervical vertebra (C2) is the most common spinal fracture type in elderly patients. However, very little is known about the biomechanical fracture mechanisms, but could play a role in fracture prevention and treatment. This study aimed to investigate the biomechanical competence and fracture characteristics of the odontoid process. A total of 42 human C2 specimens (14 female and 28 male, 71.5 ± 6.5 years) were scanned via quantitative computed tomography, divided in 6 groups (n = 7) and subjected to combined quasi-static loading at a rate of 0.1 mm/s until fracturing at inclinations of −15°, 0° and 15° in sagittal plane, and −50° and 0° in transverse plane. Bone mineral density (BMD), specimen height, fusion state of the ossification centers, stiffness, yield load, ultimate load, and fracture type according to Anderson and d'Alonzo were assessed. While the lowest values for stiffness, yield, and ultimate load were observed at load inclination of 15° in sagittal plane, no statistically significant differences could be observed among the six groups (p = 0.235, p = 0.646, and p = 0.505, respectively). Evaluating specimens with only clearly distinguishable fusion of the ossification centers (n = 26) reveled even less differences among the groups for all mechanical parameters. BMD was positively correlated with yield load (R² = 0.350, p < 0.001), and ultimate load (R² = 0.955, p < 0.001), but not with stiffness (p = 0.070). Type III was the most common fracture type (23.5%). These biomechanical outcomes indicate that load direction plays a subordinate role in traumatic fractures of the odontoid process in contrast to BMD which is a strong determinant of stiffness and strength. Thus, odontoid fractures appear to result from an interaction between load magnitude and bone quality

First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration >1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone. Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging. Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9-71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated >1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%). The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration

Renal Osteodystrophy is a type of metabolic bone disease characterized by bone mineralization deficiency due to electrolyte and endocrine abnormalities. Patients with chronic kidney disease (CKD) are more likely to experience falls and fractures due to renal osteodystrophy and the high prevalence of risk factors for falls. Treatment involves medical management to resolve the etiology of the underlying renal condition, as well as management (and prevention) of pathological fractures. A 66-year-old female patient, with severe osteoporosis and chronic kidney disease undergoing haemodialysis, has presented with multiple fractures along the years. She was submitted to bilateral proximal femoral nailing as fracture treatment on the left and prophylactically due to pathological bone injury on the right, followed by revision of the left nail with a longer one after varus angulation and fracture distal to the nail extremity. Meanwhile, the patient suffered a pathological fracture of the radial and cubital diaphysis and was submitted to conservative treatment with cast, with consolidation of the fracture. Posteriorly, she re-fractured these bones after a fall and repeated the conservative treatment. Clinical management: There is a multidisciplinary approach to manage the chronic illness of the patient, including medical management to resolve the etiology and consequences of her chronic kidney disease, pain control, conservative or surgical fracture management and prevention of falls. The incidence of chronic renal disease is increasing and the patients with this condition live longer than previously and are more physically active. Thus, patients may experience trauma as a direct result of increased physical activity in a setting of weakened pathologic bone. Their quality of life is primarily limited by musculoskeletal problems, such as bone pain, muscle weakness, growth retardation, and skeletal deformity. A multidisciplinary approach is required to treat these patients, controlling their chronic diseases, managing fractures and preventing falls

Abstract. Objectives. Ankle fractures have an incidence of around 90,000 per year in the United Kingdom. They affect younger patients following high energy trauma and, in the elderly, following low energy falls. Younger patients with pre-existing comorbidities including raised BMI or poor bone quality are also at risk of these injuries which impact the bony architecture of the joint and the soft tissues leading to a highly unstable fracture pattern, resulting in dislocation. At present, there is no literature exploring what effect ankle fracture-dislocations have on patients’ quality of life and activities of daily living, with only ankle fractures being explored. Methods. Relevant question formatting was utilised to generate a focused search. This was limited to studies specifically mentioning ankle injuries with a focus on ankle fracture-dislocations. The number of patients, fracture-dislocation type, length of follow up, prognostic factors, complications and outcome measures were recorded. Results. 939 fractures were included within the studies. Eight studies looked at previously validated foot and ankle scores, two primarily focused on the American Orthopaedic Foot and Ankle Society score (AOFAS), three on the Foot and Ankle Outcome Score (FAOS), and one study on the Olerud–Molander Score (OMAS). Patient, injury, and management factors were identified as being associated with poorer clinical outcomes. Conclusions. Not only are age and BMI a risk factor for posttraumatic osteoarthritis but they were also identified as prognostic indicators for functional outcome in this review. Patients sustaining a concurrent fracture-dislocation were found to have poorer clinical outcomes, and the timing and success of reduction further influenced outcomes. This review found that the quality of reduction was directly related to the patients’ functional outcomes post-follow up, and the risk of developing posttraumatic osteoarthritis, which was more frequent in patients sustaining Bosworth fractures, posterior malleolar fractures, and in patients over 35 years old

Abstract. Objectives. There is renewed interest in bi-unicondylar arthroplasty (Bi-UKA) for patients with medial and lateral tibiofemoral osteoarthritis, but a spared patellofemoral compartment and functional cruciate ligaments. The bone island between the two tibial components may be at risk of tibial eminence avulsion fracture, compromising function. This finite element analysis compared intraoperative tibial strains for Bi-UKA to isolated medial unicompartmental arthroplasty (UKA-M) to assess the risk of avulsion. Methods. A validated model of a large, high bone-quality tibia was prepared for both UKA-M and Bi-UKA. Load totalling 450N was distributed between the two ACL bundles, implant components and collateral ligaments based on experimental and intraoperative measurements with the knee extended and appropriately sized bearings used. 95th percentile maximum principal elastic strain was predicted in the proximal tibia. The effect of overcuts/positioning for the medial implant were studied; the magnitude of these variations was double the standard deviation associated with conventional technique. Results. For all simulations, strains were an order of magnitude lower than that associated with bone fracture. Highest strain occurred in the spine, under the anteromedial ACL attachment, adjacent to transverse overcut of the medial component. Consequently, Bi-UKA had little effect on strain: <10% increases were predicted when compared to UKA-M with equivalent medial cuts/positioning. However, surgical overcutting/positional variation that resulted in loss of anteromedial bone in the spine increased strain. The biggest increase was for lateral translation of the medial component: 44% and 42% for UKA-M and Bi-UKA, respectively. Conclusions. For a large tibia with high bone quality, Bi-UKA with a well-positioned lateral implant had no tangible effect on the risk of tibial eminence avulsion fracture compared to UKA-M. Malpositioning of the medial component that removes bone from the anterior spine could prove problematic for smaller tibiae. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Abstract. Objectives. Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but monolithic implants disrupt the natural homeostasis of bone which leads to bone loss over time. This can cause problems if the implant needs to be revised. This study aimed to demonstrate that tibial implants made from titanium lattice could replace the tibial condyle surface while minimising disruption of the bone's natural mechanical loading environment. A secondary aim was to determine whether implants perform better if they replicate more closely bone's mechanical modulus, anisotropy and spatial heterogeneity. This study was conducted in a human cadaveric model. Methods. In a cadaveric model, UKA and TKA procedures were performed on 8 fresh-frozen knee specimens by a board-certified consultant orthopaedic surgeon, using tibial implants made from conventional monolithic material and titanium lattice structures. Stress at the bone-implant interfaces was measured with pressure film and compared to the native knee. Results. Titanium lattice implants were able to restore the mechanical environment seen in the native tibia for both UKA and TKA designs. Maximum stress at the bone-implant interface ranged from 1.2–3.3MPa compared to 1.3–2.7MPa for the native tibia. The conventional UKA and TKA implants reduced the maximum stress in the bone by a factor of 10 and 9.7 respectively. The conventional UKA and TKA implants caused 71% and 77% of bone surface area to be underloaded compared to the native tibia. Conclusions. Titanium lattice implants can maintain the natural mechanical loading in the proximal tibia after UKA and TKA. This may help maintain normal bone homeostasis throughout the life of the implant. These encouraging data indicate normal bone homeostasis can be maintained after arthroplasty using manufacturing methods already in widespread use. This would maintain bone quality throughout the life of the implant and alleviate complications at revision surgery

Introduction and Objective. Type 2 diabetes mellitus (T2DM), and the often concurrent obesity, causes metabolic changes that affect many organs and tissues, including bone. Despite a normal or even higher bone mineral density (BMD), T2DM has often been associated with a higher fracture risk, indicating a compromised bone quality. In this work, we use a novel congenic leptin receptor-deficient BioBreeding Diabetes Resistant rat (BBDR.cg.lepr.cp) to investigate the impact of T2DM and obesity on bone morphology and architecture at the microscale. Materials and Methods. Two different anatomical locations, i.e., femur and cranium, were studied combining micro-computed X-ray tomography (micro-CT) with scanning electron microscopy (SEM). Micro-CT data were examined using advanced image analysis tools in three-dimensions (3D). Results. Both parietal bones and femurs were smaller, i.e., thinner and shorter, respectively, in diabetic animals compared to healthy controls. Image analysis of the sagittal suture revealed a reduced suture width and length in diabetic animals, suggesting an altered bone apposition rate. Histomorphometry analysis from micro-CT data highlighted differences in microstructure of both trabecular and cortical femur between diabetic and healthy rats. In particular, bone volume fraction (BV/TV) was lower in the T2DM group, while trabecular spacing (Tb.Sp) was increased, overall indicating a higher porosity in diabetic trabecular bone. SEM revealed the presence of extended portions of hyper-mineralized cartilage in the distal femur of the diabetic animals. Conclusions. Micro-CT analyses, combined with SEM imaging, suggest that T2DM impacts bone growth and remodelling, in turn leading to differences in the structural organization at the microscale

Introduction and Objective. Plating of geriatric distal femoral fractures with Locking Compression Plate Distal Femur (LCP–DF) often requires augmentation with a supplemental medial plate to achieve sufficient stability allowing early mobilization. However, medial vital structures may be impaired by supplemental medial plating using a straight plate. Therefore, a helically shaped medial plate may be used to avoid damage of these structures. Aim of the current study was to investigate the biomechanical competence of augmented LCP–DF plating using a supplemental straight versus helically shaped medial plate. Materials and Methods. Ten pairs of human cadaveric femora with poor bone quality were assigned pairwise for instrumentation using a lateral anatomical 15-hole LCP–DF combined with a medial 14-hole LCP, the latter being either straight or manually pre-contoured to a 90-degree helical shape. An unstable distal femoral fracture AO/OTA 33–A3 was simulated by means of osteotomies. All specimens were biomechanically tested under non-destructive quasi-static and destructive progressively increasing combined cyclic axial and torsional loading in internal rotation, with monitoring by means of optical motion tracking. Results. Initial axial stiffness and torsional stiffness in internal and external rotation for straight double plating (548.1 ± 134.2 N/mm, 2.69 ± 0.52 Nm/° and 2.69 ± 0.50 Nm/°) was significantly higher versus helical double plating (442.9 ± 133.7 N/mm, 2.07 ± 0.32 Nm/° and 2.16 ± 0.22 Nm/°), p≤0.04. Initial interfragmentary axial displacement and flexural rotation under 500 N static loading were significantly smaller for straight plating (0.11 ± 0.14 mm and 0.21 ± 0.10°) versus helical plating (0.31 ± 0.14 mm and 0.68 ± 0.16°), p<0.01. However, initial varus deformation under this loading remained not significantly different between the two fixation methods (straight: 0.57 ± 0.23°, helical: 0.75 ± 0.34°), p=0.08. During dynamic loading, within the course of the first 4000 cycles the movements of the distal fragment in flexion were significantly bigger for helical over straight plating (1.03 ± 0.33° versus 0.40 ± 0.20°), p<0.01. However, no significant differences were observed between the two fixation methods in terms of varus, internal rotation, axial and shear displacements at the fracture site, and number of cycles to failure. Conclusions. Augmented lateral plating of unstable distal femoral fractures with use of supplemental helically shaped medial plate was associated with more elastic bone-implant construct behavior under static and dynamic loading compared to straight double plating. Both fixation methods resulted in comparable number of cycles to failure. From a biomechanical perspective, the more elastic helical double plating may be considered as useful alternative to straight plating, potentially reducing stress risers at the distal bone-implant interface due to its ameliorated damping capacities

Introduction and Objective. Trochanteric fractures are associated with increasing incidence and represent serious adverse effect of osteoporosis. Their cephalomedullary nailing in poor bone stock can be challenging and associated with insufficient implant fixation in the femoral head. Despite ongoing implant improvements, the rate of mechanical complications in the treatment of unstable trochanteric fractures is high. Recently, two novel concepts for nailing with use of a helical blade – with or without bone cement augmentation – or an interlocking screw have demonstrated advantages as compared with single screw systems regarding rotational stability and cut-out resistance. However, these two concepts have not been subjected to direct biomechanical comparison so far. The aims of this study were to investigate in a human cadaveric model with low bone density (1) the biomechanical competence of cephalomedullary nailing with use of a helical blade versus an interlocking screw, and (2) the effect of cement augmentation on the fixation strength of the helical blade. Materials and Methods. Twelve osteoporotic and osteopenic femoral pairs were assigned for pairwise implantation using either short TFN-ADVANCED Proximal Femoral Nailing System (TFNA) with a helical blade head element, offering the option for cement augmentation, or short TRIGEN INTERTAN Intertrochanteric Antegrade Nail (InterTAN) with an interlocking screw. Six osteoporotic femora, implanted with TFNA, were augmented with 3 ml cement. Four study groups were created – group 1 (TFNA) paired with group 2 (InterTAN), and group 3 (TFNA augmented) paired with group 4 (InterTAN). An unstable pertrochanteric OTA/AO 31-A2.2 fracture was simulated. All specimens were biomechanically tested until failure under progressively increasing cyclic loading featuring physiologic loading trajectory, with monitoring via motion tracking. Results. T-score in groups 3 and 4 was significantly lower compared with groups 1 and 2, p=0.03. Stiffness (N/mm) in groups 1 to 4 was 335.7+/−65.3, 326.9+/−62.2, 371.5+/−63.8 and 301.6+/−85.9, being significantly different between groups 3 and 4, p=0.03. Varus (°) and femoral head rotation around neck axis (°) after 10,000 cycles were 1.9+/−0.9 and 0.3+/−0.2 in group 1, 2.2+/−0.7 and 0.7+/−0.4 in group 2, 1.5+/−1.3 and 0.3+/−0.2 in group 3, and 3.5+/−2.8 and 0.9+/−0.6 in group 4, both with significant difference between groups 3 and 4, p<=0.04. Cycles to failure and failure load (N) at 5° varus in groups 1 to 4 were 21428+/−6020 and 1571.4+/−301.0, 20611+/−7453 and 1530.6+/−372.7,21739+/−4248 and 1587.0+/−212.4, and 18622+/−6733 and 1431.1+/−336.7, both significantly different between groups 3 and 4, p=0.04. Conclusions. From a biomechanical perspective, cephalomedullary nailing of trochanteric fractures with use of helical blades is comparable to interlocking screw fixation in femoral head fragments with low bone density. Moreover, bone cement augmentation of helical blades considerably improves their fixation strength in poor bone quality

Introduction and Objective. Individuals with type 2 diabetes (T2D) have a 3-fold increased risk of bone fracture compared to non-diabetics, with the majority of fractures occurring in the hip, vertebrae and wrists. However, unlike osteoporosis, in T2D, increased bone fragility is generally not accompanied by a reduction in bone mineral density (BMD). This implies that T2D is explained by poorer bone quality, whereby the intrinsic properties of the bone tissue itself are impaired, rather than bone mass. Yet, the mechanics remain unclear. The objective of this study is to (1) assess the fracture mechanics of bone at the structural and tissue level; and (2) investigate for changes in the composition of bone tissue along with measuring total fluorescent advanced glycation end products (fAGEs) from the skin, as T2D progresses with age in Zucker diabetic fatty (ZDF (fa/fa)) and lean Zucker (ZL (fa/+)) rats. Materials and Methods. Right ulnae and skin sections were harvested from ZDF (fa/fa) (T2D) and ZL (fa/+) (Control) rats at 12 and 46 weeks (wks) of age (n = 8, per strain and age) and frozen. Right ulnae were thawed for 12 hrs before micro-CT (μCT) scanning to assess the microstructure and measure BMD. After scanning, ulnae were loaded until failure via three-point bending. Fourier transform-infrared microspectroscopy (FTIR) was used to measure various bone mineral- and collagen-related parameters such as, mineral-to-matrix ratio and nonenzymatic cross-link ratio. Finally, fAGEs were measured from skin sections using fluorescence spectrometry and an absorbance assay, reported in units of ng quinine/ mg collagen. Results. At 12 and 46 wks bone size was significantly smaller in length (p < 0.01), cortical area (p < 0.001) and cross-sectional moment of inertia (p < 0.001) in T2D rats compared to age-matched controls. A slight reduction in BMD was observed in T2D rats compared to controls at both ages, however, this was not significant. Structural properties of T2D bone were significantly altered at 12 and 46 wks, with bending rigidity increasing approximately 2.5-fold and 1.5-fold in control and T2D rats with age, respectively (p < 0.0001). Similarly, yield and ultimate moment significantly reduced in T2D rats with age in comparison to controls (p < 0.0001). Energy absorbed to failure was significantly reduced in T2D rats at 46 weeks of age compared to controls (p < 0.01). The amount of energy absorbed to failure increased approximately 1.4-fold from 12 to 46 wks in control rats, however, in T2D rats a reduction was seen with age, although not significant. At 12 wks, there was no significant deficits in tissue material properties, whereas, at 46 wks a significant reduction in yield stress, yield strain and ultimate stress was observed for T2D rats in comparison to controls (p < 0.05). Conclusions. These findings show that longitudinal growth is impaired as early as 12 wks of age and by 46 wks bone size is significantly reduced in T2D rats compared to controls. The reduction in T2D structural properties is likely attributed to the bone geometry deficits. At 12 wks of age, the tissue material properties are not altered in T2D bone versus controls. However, at 46 wks, bone strength is reduced in T2D, leading to the conclusion that tissue properties are altered as the disease progresses

Osteoporosis is a common disorder characterized by low bone mass and reduced bone quality that affects the bone strength negatively and leads to increased risk of fracture. Bone mineral density (BMD) has been the standard instrument for the diagnosis of osteoporosis and the determination of fracture risk. Despite the approximation of the bone mass, BMD does not provide information about the bone structure. Trabecular bone score (TBS), which provides an indirect evaluation of skeletal microarchitecture, is calculated from dual X-ray absorptiometry and a simple and noninvasive method that may contribute to the prediction of osteoporotic fractures in addition to the measure of bone density. The goal of this study was to determine the mean TBS values in healthy postmenopausal women and the overall association between TBS and demographic features, bone mineral density of the lumbar spine and femoral neck and bone mineral density to body mass index ratio (BMD/BMI) of the lumbar spine. Fifty-three postmenopausal healthy women participated. The bone mineral density of the lumbar spine and femoral neck were measured dual X-ray absorptiometry. Anteroposterior lumbar spine acquisitions were used to calculate TBS for L1-L4. Age, height, weight, BMI and the ratio of BMD to BMI, which was considered to be a simple tool for assessing fracture risk in especially obese individuals, were calculated. The relationship between TBS and other variables was examined using Spearman's rank correlation coefficients. Mean BMD of the lumbar spine and the femoral neck were 0.945 ± 0.133 and 0.785 ± 0.112 g/cm2, respectively (Table 1). Mean TBS was 1.354 ± 0.107. There was a significant positive moderate correlation between TBS and total lumbar BMD/BMI ratio (r=0.595, pTBS values of postmenopausal women were negatively correlated with age and BMI and positively with bone mineral density and BMD/BMI ratio. The ratio between lumbar BMD and BMI presented a stronger correlation with TBS than that of BMD with TBS. Because of the better correlation, the BMD/BMI ratio may be used as a simple tool for the assessment of the risk of fractures. Further investigation may be needed to evaluate the factors influencing exercise intervention on TBS on this population of patients