Conventional radiographs and bone mineral density are commonly used to predict cage subsidence, though their accuracy can be limited by several factors. Magnetic resonance imaging (MRI)-based measurement of vertebral bone quality (VBQ) and endplate bone quality (EBQ) offer a more detailed assessment of bone quality and subsidence risk. This study aims to evaluate the accuracy of MRI-based VBQ and EBQ in predicting cage subsidence in anterior cervical spine surgery patients. A comprehensive search was conducted across databases including PubMed, Europe PMC, ScienceDirect, and Google Scholar using keywords such as "Magnetic Resonance Imaging," "MRI," "Vertebral Bone Quality," "Endplate Bone Quality," "Cage Subsidence," "Anterior Cervical Spine Surgery," "ACDF," "ACCF," combined with Boolean operators "AND" and "OR" up to November 2024. The risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2), with the primary outcome focusing on VBQ and EBQ values, and secondary outcomes examining the area under the curve (AUC), sensitivity, and specificity of VBQ and EBQ. Nine retrospective cohort studies involving 911 patients were included. Pooled analysis showed that high VBQ and EBQ scores were significantly associated with increased subsidence risk (odds ratio [OR]: 2.63, 95% confidence interval [CI]: 1.51-4.60, p = 0.0007). Pooled sensitivity and specificity for VBQ were 78.9% (95% CI: 72.5-85.3%) and 85.7% (95% CI: 82.2-93.1%), respectively, with an AUC of 0.865. EBQ demonstrated pooled sensitivity of 81.8% and specificity of 88.7%, with an AUC of 0.890. The cutoff values for VBQ and EBQ ranged from 2.68 to 3.445 and 1.973 to 4.7, respectively. MRI-based VBQ and EBQ scores demonstrate strong diagnostic accuracy for predicting cage subsidence in anterior cervical spine surgery. These scores could aid in preoperative risk assessment, though further research should aim to standardize MRI protocols and validate cutoff values across diverse populations.

Split Feeding for semi-heavy laying hens from 105 to 120 weeks of age: Performance, egg quality, biochemical parameters, reproductive tract morphometry and bone quality.

Total knee arthroplasty (TKA) remains a highly successful and frequently performed procedure with variability in surgeon preferences regarding implant fixation and patellar resurfacing. This study aimed to characterize current practice patterns among members of the Knee Society and to identify key factors influencing implant fixation and patella resurfacing. A 23-question survey was distributed to 216 members of the Knee Society. The survey assessed demographic information, primary TKA volume, fixation technique preferences, patellar resurfacing practices, and the clinical rationale for these decisions. Responses were collected over a 4-week period in May 2025. Descriptive statistics were used to summarize the data. The response rate was 48.1% (104 surgeons), with 52 (50.0%) being in practice greater than 25 years and 39 (37.9%) performing 201 to 300 primary TKAs annually. Cemented fixation was dominant, with an average use rate of 72.9%; 67.3% (70 surgeons) used both cemented and cementless implants, with an average cementless use of 35.8% of cases. Age (70.0%) and bone quality (82.9%) were the most cited indications for cementless use. Conversely, 35.6% (37 surgeons) reported using cemented fixation in all patients. Patellar resurfacing practices varied widely, with 34.7% (33 surgeons) reporting always resurfacing and individual rates ranging from 0 to 100%. In total, 40.2% (41 surgeons) of respondents have said that their indications have changed in the past five years; resurfacing was most influenced by degree of arthritis (53.7%), patellar tracking (23.1%), and size/thickness (21.0 to 31.6%). Among surgeons performing cementless TKA, patellar resurfacing remained heterogeneous, and 40% (24 surgeons) still preferred cemented patellar components. Cemented fixation in primary TKA remains the standard among expert TKA surgeons, though cementless techniques are increasingly used in select patients. Patellar resurfacing practices remain highly variable, reflecting individualized decision-making. These findings highlight evolving trends and underscore the need for continued research and consensus in primary TKA.

Osteonecrosis of the femoral head (ONFH), femoral neck stress fracture (FNSF), and subchondral insufficiency fracture (SIF) are distinct yet clinically overlapping causes of non-arthritic hip pain. All three conditions threaten femoral head viability via distinct pathophysiologic mechanisms and may lead to fracture displacement (FNSF) and irreversible collapse (ONFH, SIF, and displaced FNSF), ultimately necessitating arthroplasty if not identified and managed early. These conditions frequently present with groin pain and unremarkable radiographs in their early stages. Imaging may be normal or show generalized bone marrow edema. MRI is the most sensitive modality for detection; however, accurate diagnosis requires the integration of specific imaging features with the synthesis of the patient's past medical history, including age, activity level, and bone quality. ONFH identified before collapse may be amenable to joint-preserving procedures, such as core decompression. FNSF requires urgent recognition and non-weight-bearing precautions to avoid displacement and vascular injury. SIF may be managed conservatively with protected weight-bearing and monitoring. Despite the expertise of experienced examiners and advanced imaging techniques, the initial diagnosis is frequently incorrect, and treatment options only become clear with timely follow-up and serial imaging. This review highlights diagnostic distinctions among ONFH, FNSF, and SIF, emphasizing clinical context, imaging-based differentiation, and appropriate management. Accurate early classification is crucial for guiding management decisions and preventing collapse of the femoral head or femoral neck displacement.

Effects of exercise training on bone health in elderly people with type 2 diabetes without osteoporosis: A randomised clinical trial.

This review presents how surgeons should choose femoral interference screw in anterior cruciate ligament (ACL) reconstruction - insertion direction (inside-out vs outside-in), tunnel shape (round vs rectangular), screw position (anterior vs posterior), and screw material (metal, bioabsorbable, PEEK, magnesium) - to balance fixation strength, anatomic fidelity, and revision feasibility. Inside-out maximizes aperture compression and preserves the lateral femoral cortex but requires deep flexion and precise trajectory (risk of iatrogenic cartilage contact/posterior wall breach). Outside-in improves visualization and guide control yet needs a large lateral cortical socket and can push the bone plug intra-articularly as the screw advances from cortex to joint. Rectangular tunnels better match the native footprint, improving rotational control and interface congruity, while round tunnels simplify preparation but allow plug rotation and may use bone less efficiently at the aperture. Posterior screw placement (particularly with the inside-out technique) enhances cancellous-to-cancellous compression but risks posterior cortical breach injury; anterior placement protects fibers and favors footprint fidelity but may reduce cancellous compression. Metal offers high stiffness and no tapping but creates MRI artifact and requires removal if present at revision. Bioabsorbable materials avoid artifact/removal yet are weaker and may fracture in sclerotic tunnels. PEEK (metal-like without artifact) and magnesium (osteoconductive/resorbable) are promising but lack long-term data. No single method is universally optimal. Decisions should be individualized to visualization needs, cortical/bone-stock preservation, expected revision strategy, and patient factors (age, activity, bone quality).

Cervical Paraspinal Muscle Morphometry and Mechanical Failure: A Propensity-Matched Analysis.

Total knee arthroplasty (TKA) is an effective treatment for advanced gonarthrosis. This retrospective study compares cementless versus hybrid fixation in TKA, an under-investigated comparison in the literature, to describe mid-term clinical, radiographic, and perioperative outcomes between both fixation strategies. We conducted a retrospective cohort study of 166 patients (age 50-70, adequate bone quality) undergoing primary cruciate-retaining TKA from November 2019 to May 2024. Fixation type was selected by the treating surgeons according to intraoperative assessment of tibial bone stock and press-fit stability. Patients were divided into two groups based on fixation: uncemented (cementless) vs. hybrid (cementless femoral, cemented tibial). Clinical (pain, function) and radiographic outcomes, perioperative complications, and surgical time were compared. Functional outcomes were assessed with Hospital for Special Surgery (HSS) and WOMAC scores; quality of life with the EQ-5D. A propensity score-matched analysis (1:1) was additionally performed to mitigate measured baseline confounding, matching on age, sex, body mass index (BMI), Charlson comorbidity index and preoperative HSS score. The mean follow-up was 36.8 ± 18.7months. Uncemented fixation was associated with significantly shorter surgical time (65.2 ± 12.4 vs. 78.6 ± 15.1min; p = 0.032), a modestly greater postoperative pain reduction on the VAS (7.25 ± 2.02 vs. 6.41 ± 1.94 points; p = 0.012), and a lower observed rate of late complications (1.2% vs. 10.8%; p = 0.028) compared to hybrid. The incidence of aseptic loosening was lower in the uncemented group (0.0% vs. 3.6%; p = 0.029), as was the presence of radiolucent lines (6.0% vs. 18.1%; p = 0.032). No significant differences were found in postoperative range of motion, HSS score improvements, WOMAC, or EQ-5D index between groups. The propensity-matched sub-analysis (n = 150) yielded directionally consistent findings, although these analyses reduce but do not eliminate residual confounding and remain underpowered for rare outcomes. Cementless TKA was associated with comparable mid-term functional outcomes to hybrid fixation, together with shorter operative time and lower observed rates of radiolucent lines and late complications. The difference in pain reduction was statistically significant but modest, and radiographic findings and rare events should be viewed as hypothesis-generating rather than as evidence of superior fixation performance or long-term implant durability. These findings suggest that cementless fixation may represent a reasonable alternative to hybrid fixation in appropriately selected patients, although longer-term prospective comparative studies are required to confirm implant survivorship and clarify the clinical relevance of these observations.

Osteoarthritis (OA) is a multifaceted joint disease which poses significant socioeconomic burdens and remains a significant clinical challenge. Evidence suggests that structural and mechanical changes in subchondral bone influence the pathogenesis and development of OA, leading to diminished bone quality and cartilage degeneration. While changes in microstructure and tissue scale elastic properties are well reported, the tissue yield response of subchondral bone in OA and their correlation with compositional changes have not been investigated. Here, we performed quasistatic micropillar compression and nanoindentation within the subchondral bone plate and trabeculae of hydrated non-diseased (ND) and OA affected specimens retrieved from the distal tibia in vivo. The micropillars, extracted by laser ablation, exhibited a taper angle which mandated the use of an in silico micropillar compression routine to back-calculate elastic modulus and strength of the bone tissue that comprised each micropillar. Elastic modulus remained unchanged between ND and OA subchondral bone, whereas strength increased from 46.0 MPa to 57.3 MPa in OA subchondral trabecular bone but not in the bone plate. Micropillar matched Raman spectroscopy and quantitative backscattered electron imaging revealed mineralisation is the underlying determinant of elastic modulus and strength at the microscale. By combining micromechanical and tissue compositional analyses, we investigated how the mechanical properties are related and how these properties are affected in subchondral bone by OA. STATEMENT OF SIGNIFICANCE: Osteoarthritis imposes significant socioeconomic burden, necessitating ever improving treatment strategies. Abnormal mechanical forces at the joint, such as injury, overloading, or aging are associated with osteoarthritis development. While healthy tissue is well understood, the impact of diseases on tissue mechanical properties needs to be brought on a similar level of understanding. We present in this study the first use of micropillar compression for assessing the tissue scale compressive strength of subchondral bone in osteoarthritis. Strength was increased in osteoarthritis compared to non-diseased tissue only in trabeculae subjacent to the bone plate. Compositional analysis confirmed mineralisation as a key determinant of tissue mechanical properties. This integration of micromechanical and compositional analyses sheds light on tissue properties and how these are affected by osteoarthritis in subchondral bone.

This study aimed to evaluate the diagnostic performance of a novel MRI-based parameter-MRI signal intensity per unit vertebral volume-in identifying low bone mineral density (BMD) in children and adolescents, alongside established MRI metrics including mean L1-L4 signal intensity and vertebral bone quality (VBQ) score. The study included 106 osteoporotic patients (aged 5-18 years) who had not yet reached 18 years of age, and 46 age-matched controls. Subjects were grouped into childhood (5-11 years) and adolescence (> 12 years). Using 1.5 T MRI, mean L1-L4 signal intensity, VBQ score, and signal intensity per unit volume were calculated. MRI findings were compared using t-tests and ANOVA; diagnostic accuracy was assessed via ROC curve analysis. In the childhood group, all MRI parameters significantly differed between low bone mineral density and control subjects (p < 0.05). In adolescents, only mean signal intensity and signal intensity per unit volume were significant. The new parameter demonstrated the highest diagnostic value, with AUCs of 0.792 and 0.836 in childhood and adolescence groups, respectively. MRI signal intensity per unit vertebral volume showed superior performance in detecting low BMD compared to existing MRI-based indices. This parameter offers a radiation-free, size-adjusted alternative to DXA, particularly valuable in pediatric patients requiring long-term monitoring.

Diabetes-induced osteopathy represents a clinically significant but under recognised complication of both type 1 and type 2 diabetes, characterised by increased fracture risk despite normal or modestly reduced bone mineral density. This paradox reflects deterioration in bone quality driven by advanced glycation end products, oxidative stress, chronic inflammation, impaired osteoblast function, enhanced osteoclast activity and disrupted osteocyte signalling. Although experimental models have provided valuable mechanistic insights, current chemically induced, diet-induced, and genetic systems each reproduce only selective aspects of the human disease. Most models prioritise metabolic validation, particularly hyperglycaemia, while skeletal endpoints are often secondary and incompletely characterised. Moreover, reductions in bone mineral density do not consistently correlate with microarchitectural or biomechanical deficits. A mechanism-oriented framework that integrates metabolic, structural, molecular, and biomechanical assessments may better capture disease complexity. Refining experimental design and endpoint standardisation could enhance translational relevance and support the development of therapeutic strategies targeting bone fragility beyond glycaemic control.

Study DesignExperimental ex vivo biomechanical cadaver study.ObjectivesThoracic pedicle screws are essential for stabilizing spinal injuries, but misplacement remains a frequent complication. While many studies focus on neurovascular injuries, the impact of the degree of lateral misplacement (offset) on the biomechanical stability of thoracic pedicle screws has not been examined. Therefore, this study aimed to evaluate the influence of lateral offset on pullout force (POF) and peak insertion torque (PIT), and to analyse additional factors such as screw diameter, screw length, and bone quality.MethodsIn this ex vivo cadaveric study, 61 thoracic vertebrae (T1-T12) from seven human cadavers were instrumented using pedicle screws placed with predefined lateral offsets via 3D-printed templates. Each vertebra received one optimal and one offset screw for pairwise comparison. Biomechanical testing included cyclic loading followed by axial pullout testing. Linear mixed-effects models assessed the influence of offset, screw diameter, screw length, and bone density on POF and PIT.ResultsLateral offset significantly reduced POF and PIT. Each millimeter of offset decreased POF by 41.1 N (-9.2%; p<0.001) and PIT by 0.079 Nm (-5.9%; p=0.002). Larger screw diameter significantly increased both POF and PIT (p=0.020; p<0.001). Screw length and bone quality showed no significant independent effects. POF and PIT were strongly correlated (r=0.637, p<0.001).ConclusionsLateral offset significantly reduced both pullout force and peak insertion torque of thoracic pedicle screws, demonstrating a progressive loss of biomechanical stability with increasing misplacement. These findings underline the biomechanical relevance of accurate thoracic pedicle screw placement.

Improving bone mineral density assessment in total shoulder arthroplasty: assessment of phantom-calibrated Hounsfield units in the glenoid and proximal humerus.

Anterior cervical discectomy and fusion (ACDF) is a well-established treatment for cervical degenerative disease (CDD). Nevertheless, its anterior approach carries inherent risks to critical neck structures, prompting the exploration of posterior fusion alternatives for selected patients. Traditional anterior cervical discectomy and fusion (ACDF) for cervical degenerative disease involves navigating complex anterior neck anatomy with potential risks to critical neurovascular structures, motivating the development of safer posterior fusion alternatives. Twenty-four fresh C5-C6 segments from adult goats were randomly assigned to the intact, ACDF, and CILC groups (n = 8 per group). After confirming the anatomical similarity between goat and human cervical spines via three-dimensional reconstruction, corresponding surgical procedures were performed at the C5-C6 level. Range of motions (ROMs) in flexion-extension, lateral bending, and axial rotation were measured under a pure moment of 1.5N·m using a material testing machine. A finite element model of C3-C7 was developed based on computed tomography data from healthy adults. ACDF and CILC procedures were simulated, with a 1N·m moment and 73.6N pre-load applied to analyse the stress distribution in adjacent segment discs, facet cartilage, and implants. Anatomical measurements confirmed a high similarity between goat and human C5-C6 segments (P > 0.05), validating its use as an experimental model. In biomechanical tests, both CILC and ACDF significantly reduced segmental motion (P < 0.001). Compared with ACDF, CILC demonstrated greater ROM in flexion (3.31° vs. 1.52°, P < 0.05), but superior stability in extension (1.86° vs. 3.86°) and axial rotation (left: 5.89° vs. 8.19°; right: 6.11° vs. 8.89°) (P < 0.05). Finite element analysis confirmed model reliability, demonstrating close alignment between predicted and reported ROM values. CILC generated lower or comparable stress in C3/4 and C4/5 discs compared with ACDF, but higher stress at C5/6. Moreover, CILC resulted in higher facet joint contact forces and implant stress than ACDF, particularly during flexion and extension. Although CILC demonstrates biomechanical performance comparable to ACDF with specific advantages in controlling extension and axial rotation without significant advantages, its posterior minimally invasive approach effectively avoids neurovascular risks associated with anterior surgery. The device provides a safer alternative for cervical fusion, particularly in cases with complex anterior anatomy or those requiring revision surgery. However, the observed higher facet and implant stresses underscore the need for careful patient selection, particularly regarding pre-existing facet joint condition and bone quality.

Osteoporosis is a systemic skeletal disorder characterized by impaired bone microarchitecture and reduced bone strength arising from dysregulated coupling between osteoclast-mediated resorption and osteoblast-driven formation. Estrogen deficiency, chronic inflammation, oxidative stress, and altered RANKL/OPG signaling amplify osteoclastogenesis while suppressing Wnt/β-catenin-dependent osteoblast differentiation, resulting in progressive trabecular thinning and cortical porosity. Although antiresorptive agents and anabolic therapies reduce fracture risk, they do not fully restore bone quality, microvascular integrity, or osteoimmune balance. Platelet-derived biomaterials (PDBs), including platelet-rich plasma, platelet-rich fibrin, platelet lysates, and platelet-based hydrogels, represent autologous bioactive systems enriched with platelet-derived growth factor, transforming growth factor-β, vascular endothelial growth factor, insulin-like growth factor-1, and bioactive lipid mediators. Upon activation, PDBs provide an early burst and sustained release of growth factors within a fibrin matrix that supports mesenchymal stem cell recruitment, RUNX2- and Osterix-mediated osteogenic differentiation, extracellular matrix deposition, and angiogenic coupling through VEGF-driven neovascularization. Concurrently, PDBs modulate osteoclast activity by influencing the RANKL/OPG axis, promoting macrophage polarization toward an M2 reparative phenotype, and attenuating inflammatory cytokine signaling. Integration of PDBs with osteoconductive scaffolds and nanostructured delivery platforms further enhances mechanical stability, local retention, and spatiotemporal biofactor presentation in osteoporotic bone defects. Preclinical evidence demonstrates improvements in bone mineral density, trabecular architecture, and fracture repair; emerging clinical applications in spinal fusion and fracture management suggest translational promise. However, variability in platelet concentration, activation protocols, and dosing standardization remains a barrier to widespread clinical adoption. PDB-based regenerative strategies therefore offer a mechanistically targeted and clinically adaptable approach to restoring skeletal integrity in osteoporosis.

Osteoporosis is a major global health burden and often remains undiagnosed until fragility fractures occur. Dual-energy x-ray absorptiometry (DXA) is underutilized in routine practice. Computed tomography (CT) scans obtained for other indications offer an opportunity for opportunistic bone quality assessment without additional radiation exposure. This systematic review and meta-analysis evaluated: (i) the overall diagnostic performance [area under the receiver operating characteristic curve (AUC)] of artificial intelligence (AI) algorithms for osteoporosis/nonosteoporosis screening using CT; (ii) AUC for fracture/nonfracture screening; (iii) the most frequently studied body part; and (iv) the predominant machine learning (ML) and deep learning (DL) algorithms. Following PRISMA guidelines, 2 reviewers searched PubMed, Web of Science, Scopus, and Google Scholar for English-language studies (2011 to 2025). Eligible studies used DXA as the reference standard and reported diagnostic performance metrics. Studies lacking patient-level AI assessment, using alternative reference standards, and incorrect analysis methods were excluded. Risk of bias was assessed using QUADAS-2. A random-effects meta-analysis pooled sensitivity, specificity, and AUC. Subgroup analysis was conducted by algorithm type and study size. Heterogeneity was quantified using the I2 and Q-statistic. Of 1258 screened, 31 studies were included [26/31 (83.87%) osteoporosis screening; 5/31 (16.13%) fracture screening]. For osteoporosis screening, the abdomen/lumbar spine (L-spine) was the most frequently evaluated body part [14/26 (53.85%) studies]. Within this subgroup, osteoporosis/nonosteoporosis (normal/osteopenia) [5/14 (35.71%) studies] was the most common outcome. For fracture screening, the abdomen/L-spine was the most assessed body part [4/5 (80%) studies]. Within this subgroup, fracture/nonfracture [4/4 (100%)] was the most common outcome. The pooled AUC for abdomen/L-spine osteoporosis/nonosteoporosis screening was 0.931 (95% CI: 0.926-0.936), and for abdomen/L-spine fracture/nonfracture screening was 0.863 (95% CI: 0.73-0.936). ML was used in 21/26 (80.77%) studies and DL in 4/26 (15.38%) studies for osteoporosis screening. Support vector machine (SVM) was the most common ML (13/21, 61.90%), while custom convolutional neural networks (CNNs) (3/4, 75%) predominated in DL. ML was used in 3/5 (60%) studies and DL in 1/5 (20%) studies for fracture screening. SVM was the most common ML (n=3/5, 60%), while custom CNN (1/1, 100%) predominated DL. Heterogeneity was lower for abdomen/L-spine osteoporosis/nonosteoporosis screening (I2=47.24%) than for fracture/nonfracture screening (I2=64.8%). AI algorithms applied to abdomen/L-spine demonstrate excellent performance for opportunistic osteoporosis/nonosteoporosis screening and fracture/nonfracture screening, supporting integration into routine CT interpretation to improve early detection and prevention.

Introduction: Fluoride exposure can influence bone metabolism and structure, but its effects on the mechanical properties of developing craniofacial bones remain poorly understood. Purpose: The aim of this study was to evaluate the effect of maternal sodium fluoride (NaF) exposure during gestation and lactation on bone mineral density and biomechanical properties of mandibular bone in suckling rat pups. Methodology: Twelve female Wistar rats were randomly assigned to two groups receiving either tap water (0.3 mg F⁻/L) or water supplemented with NaF (50 mg/L; equivalent to 23 mg F⁻/L) beginning four weeks before mating and continuing throughout gestation and lactation. Offspring were euthanized at 15 and 21 days of age. Bone mineral density (BMD) of the gonion and mandibular condyle was determined radiographically, and biomechanical properties of mandibular trabecular bone were evaluated by compression testing of transverse sections obtained at the level of the first molar. Structural mechanical parameters (stiffness, ultimate load, and energy absorption) were obtained from load–displacement curves, while material properties were derived from stress–strain curves. Results: Pups from fluoride-treated dams showed significantly higher BMD values in both mandibular regions compared with controls. However, fluoride exposure was associated with decreased structural mechanical parameters and reduced material properties, including stress and Young’s modulus. Conclusions: These findings indicate that maternal fluoride exposure during early development increases mandibular bone mineral density but impairs the mechanical competence of bone tissue. The results highlight the importance of considering bone quality, in addition to bone mineral density, when evaluating the effects of fluoride on skeletal tissues during development.

A novel MRI-based formal head bone quality score for predicting the prognosis of the normal hip in patients with unilateral nontraumatic osteonecrosis of the femoral head.

Litigation related to total hip arthroplasty (THA) is a growing concern. Manufacturer-specified contraindications for femoral implants may influence legal outcomes, particularly when common patient characteristics such as obesity are listed. This study identified manufacturer-listed contraindications for femoral implants used in primary THA and evaluated their medicolegal implications within the frameworks of medical negligence and informed consent law in England and Wales. The 11 most commonly used femoral implants were identified from the National Joint Registry of England, Wales, and Northern Ireland. For each implant, manufacturer surgical technique guides were reviewed to extract contraindications, relative contraindications, and warnings. A structured medicolegal analysis was conducted within the frameworks of medical negligence and informed consent law, drawing on landmark case law and peer-reviewed medicolegal scholarship, supplemented by consultation with legal professionals who specialize in orthopaedic device litigation. Two implants cited obesity or morbid obesity as a contraindication; four reported obesity as a warning. Nine implants listed inadequate bone quality as a contraindication, and two as a relative contraindication. Neuromuscular disease was contraindicated in nine implants, and a relative contraindication in two. Infection was contraindicated in all eleven implants. Vascular deficiency was a contraindication in six implants, and a relative contraindication in two. Deficient musculature was contraindicated in five implants and a relative contraindication in two. Many manufacturer-listed contraindications correspond to clinical characteristics commonly found in THA patients. These contraindications do not preclude implant use when supported by evidence and sound clinical judgement, but carry significant medicolegal implications under negligence and informed consent law. Once a manufacturer has communicated a contraindication, medicolegal scrutiny may shift to the surgeon's decision-making under two distinct frameworks, namely the standard of care and informed consent. Surgeons should know their implant-specific contraindications, ensure decisions are evidence-based and documented, and explicitly disclose elevated risks to patients.

DesignRetrospective study.ObjectiveTo evaluate the predictive performance of a simplified, MRI-derived vertebral bone quality score (VBQ) using measurements at L1/2 (VBQL1/2) for opportunistic bone quality screening, compared to the established VBQL1-4.MethodsIn patients undergoing lumbar surgery for degenerative spondylolisthesis, VBQL1/2 was assessed using circular regions of interest on sagittal T1-weighted sequences in L1 and L2, while VBQL1-4 included measurements from L1 through L4. Measurements were normalized to cerebrospinal fluid intensity at L2/3. Bone mineral density (BMD) was measured by opportunistic qCT, with osteoporosis defined as BMD < 80mg/cm3 and impaired bone quality (osteoporosis or osteopenia) as BMD < 120mg/cm3. Agreement between VBQL1/2 and VBQL1-4 was determined using the intraclass correlation coefficient (ICC), and predictive performance was evaluated using receiver operating characteristic analysis with Youden's index optimization.ResultsAmong 144 patients included ((39% male, n = 56) the median age was 69years (interquartile range 64-67). Osteopenia was present in 47% and osteoporosis in 22%, yielding 69% impaired bone quality. VBQL1/2 and VBQL1-4 showed excellent agreement (ICC: 0.988, 95% CI: 0.982-0.991). Predictive performance was comparable for osteoporosis (AUC: VBQL1/2 0.71 vs. VBQL1-4 0.69) and impaired bone quality (AUC: 0.68 vs. 0.67). For osteoporosis detection, VBQL1/2 showed a higher sensitivity (94% vs 71%) but a lower specificity (45% vs 64%), as well as for detecting impaired bone quality (sensitivity 77% vs. 47%, 56%, vs 82%).ConclusionsVBQL1/2 offers a simplified alternative to VBQL1-4 for MRI-based bone quality assessment. Further validation and threshold refinement are warranted.