Alterations in compositional and cellular properties of the subchondral bone are linked to cartilage degeneration in hip osteoarthritis.

OBJECTIVE: The subchondral bone is an emerging regulator of osteoarthritis (OA). However, knowledge of how specific subchondral alterations relate to cartilage degeneration remains incomplete. METHOD: Femoral heads were obtained from 44 patients with primary OA during total hip arthroplasty and from 30 non-OA controls during autopsy. A multiscale assessment of the central subchondral bone region comprising histomorphometry, quantitative backscattered electron imaging, nanoindentation, and osteocyte lacunocanalicular network characterization was employed. RESULTS: In hip OA, thickening of the subchondral bone coincided with a higher number of osteoblasts (controls: 3.7 ± 4.5 mm-1, OA: 16.4 ± 10.2 mm-1, age-adjusted mean difference 10.5 mm-1 [95% CI 4.7 to 16.4], p < 0.001) but a similar number of osteoclasts compared to controls (p = 0.150). Furthermore, higher matrix mineralization heterogeneity (CaWidth, controls: 2.8 ± 0.2 wt%, OA: 3.1 ± 0.3 wt%, age-adjusted mean difference 0.2 wt% [95% CI 0.1 to 0.4], p = 0.011) and lower tissue hardness (controls: 0.69 ± 0.06 GPa, OA: 0.67 ± 0.06 GPa, age-adjusted mean difference -0.05 GPa [95% CI -0.09 to -0.01], p = 0.032) were detected. While no evidence of altered osteocytic perilacunar/canalicular remodeling in terms of fewer osteocyte canaliculi was found in OA, specimens with advanced cartilage degeneration showed a higher number of osteocyte canaliculi and larger lacunocanalicular network area compared to those with low-grade cartilage degeneration. Multiple linear regression models indicated that several subchondral bone properties, especially osteoblast and osteocyte parameters, were closely related to cartilage degeneration (R2 adjusted = 0.561, p < 0.001). CONCLUSION: Subchondral bone properties in OA are affected at the compositional, mechanical, and cellular levels. Based on their strong interaction with cartilage degeneration, targeting osteoblasts/osteocytes may be a promising therapeutic OA approach. DATA AND MATERIALS AVAILABILITY: All data are available in the main text or the supplementary materials.

Patients with Periprosthetic Femoral Hip Fractures are Commonly Classified as Having Osteoporosis Based on DXA Measurements.

Periprosthetic femoral hip fractures are subject to an increasing incidence and are often considered to be related to osteoporosis. However, there are no available studies that have determined the frequency of osteoporosis in affected patients using gold standard dual-energy X-ray absorptiometry (DXA). In this retrospective comparative study, we analyzed the DXA results of 40 patients with periprosthetic femoral hip fractures who were treated surgically in our department. DXA measurements were performed at the total hip and the lumbar spine to determine bone mineral density T-scores. Data were compared to two age-, sex-, and BMI-matched control groups in which patients underwent DXA prior to aseptic revision surgery for other causes or primary THA (consisting of 40 patients each). The mean T-score in the periprosthetic fracture cohort was significantly lower (- 1.78 ± 1.78) than that of the aseptic revision (- 0.65 ± 1.58, mean difference - 1.13 [95% CI - 1.88 to - 0.37]; p = 0.001) and the primary THA cohort (- 0.77 ± 1.34, mean difference - 1.01 [95% CI - 1.77 to - 0.26]; p = 0.005). Accordingly, osteoporosis was detected more frequently (45%) in the fracture cohort compared to patients undergoing aseptic revision (12.5%) and primary THA (10%). In conclusion, almost half of the patients with periprosthetic femoral hip fractures have osteoporosis according to DXA measurements. A regular assessment of bone health in THA enables identification of patients with osteoporosis who likely benefit from initiation of osteoporosis medication and cemented stem fixation.

A clinical risk score enables early prediction of dissatisfaction 1 year after total knee arthroplasty.

PURPOSE: Dissatisfaction after total knee arthroplasty (TKA) is a prevalent and clinically relevant problem that affects approximately 10%-20% of patients. The aim of this study is to identify factors associated with dissatisfaction 1 year after TKA. METHODS: A total of 236 patients undergoing TKA were included in this prospective cohort study. Demographic data, preoperative clinical parameters (e.g., axial alignment, osteoarthritis severity) and patient-reported outcome measures (PROMs) were collected preoperatively, at 1 month and 1 year after TKA, encompassing the Knee Society Score (KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). The primary outcome was dissatisfaction 1 year after TKA, defined as ≤20 points on the KSS satisfaction scale. A risk score based on multiple regression and area under the curve (AUC) analyses was calculated to predict dissatisfaction. RESULTS: One year after TKA, 16% of the patients were dissatisfied. Dissatisfied patients were significantly younger (p = 0.023) and had a higher body mass index (BMI) (p = 0.007). No differences were observed in preoperative objective (p = 0.903) and functional KSS (p = 0.346), pain (p = 0.306), osteoarthritis severity (p = 0.358), axial knee alignment (p = 0.984) or psychological distress (p = 0.138). The likelihood of dissatisfaction at 1 year was 3.0, 4.0, 7.4, 4.3 and 2.8 times higher amongst patients aged <63.5 years, with a BMI > 30.1 kg/m2, a KOOSPain < 50%, a KSSFunction < 42 points and a KSSExpectation < 9 points (all at 1 month), respectively. Using these variables, a risk score with a maximum of 7 points was developed, demonstrating a high predictive value for dissatisfaction (AUC: 0.792 [95% confidence interval: 0.700-0.884], p < 0.001). CONCLUSION: Dissatisfaction 1 year after TKA can be predicted by a weighted risk score that includes patient age, BMI, pain, subjective functionality and unmet expectation 1 month postoperatively. Using the risk score, early detection of dissatisfaction has the potential to enable targeted interventions and improve patients' quality of life. LEVEL OF EVIDENCE: Level II, Prognostic study.

Are Synovial Inflammatory Markers Increased in Patients Who Have Aseptic Total Hip Arthroplasty Dislocation Indicated for Revision?

BACKGROUND: Previous studies have speculated on elevated synovial inflammatory markers in patients undergoing surgical revision for total hip arthroplasty (THA) dislocation. However, this assumption is based on small patient series and a full investigation according to International Consensus Meeting (ICM) criteria has not yet been performed. METHODS: Patients who had aseptic THA dislocation indicated for revision surgery were identified retrospectively. Only patients who had available diagnostic workup according to ICM 2018 criteria, including preoperative and intraoperative parameters, were included. For comparison, we analyzed a matched cohort of patients indicated for aseptic THA revision for other conditions. The 2 cohorts each consisted of 55 patients and were not different regarding age, sex, BMI, or implant fixation. RESULTS: There was no difference in synovial white blood cell count (2,238 ± 2,544 versus 2,533 ± 3,448 c/µL; P = .601), alpha-defensin quotient (0.14 ± 0.11 versus 0.19 ± 0.28; P = .207), or polymorphonuclear neutrophil percentage (% PMN) (36.7 ± 22.6 versus 31.3 ± 24.5%; P = .312) between the groups. In the dislocation cohort, 20% of patients had a synovial white blood cell count of 3,000 c/µL or higher, compared with 18% in the control cohort. However, all patients in the dislocation cohort were below the cutoff for alpha-defensin or % PMN. CONCLUSION: In patients who have aseptic THA dislocation, synovial inflammatory markers are not elevated compared with patients undergoing aseptic revision for other complications. A detailed preoperative analysis of synovial inflammatory markers using ICM criteria appears critical in patients who have a THA dislocation to exclude periprosthetic joint infection. LEVEL OF EVIDENCE: Level III, retrospective, comparative study.

Influence of health literacy on health-related quality of life after total hip arthroplasty.

INTRODUCTION: Personal knowledge about the own disease, a key component of health literacy (HL), may have a considerable impact on treatment outcomes. The purpose of this study was to investigate whether the patients' knowledge about the surgical procedure, risks, and aftercare, as well as the satisfaction with the preoperative level of information, has an influence on the health-related quality of life (HRQoL) after primary total hip arthroplasty (THA). MATERIALS AND METHODS: A total of 176 patients (68.3 ± 10.3 years, 60.8% female) were evaluated. HRQoL was assessed prior to surgery as well as one and twelve months after THA using the 12-item Short Form Questionnaire. Following standardized surgical informed consent, HL was assessed preoperatively using a self-constructed quiz score, while information satisfaction was measured with a single-item rating scale. Sociodemographic and clinical characteristics, including pain (VAS), functionality (WOMAC), and psychological distress (PHQ-4), were also assessed at baseline. Multiple linear regression analyses were performed to examine whether HL, satisfaction with information, age, social class, WOMAC, VAS, and PHQ-4 predict HRQoL at one and twelve months post-surgery. RESULTS: The average HL quiz score was 23 ± 5.1 out of a possible 33 points. Social class index significantly influenced HL (p < 0.001). A weak correlation between HL and age (r = 0.23, p = 0.01) and no correlation between HL and psychological distress (p = 0.868) were observed. One month after THA, physical HRQoL was significantly predicted by the WOMAC index (p = 0.031) and subjective satisfaction with information (p = 0.022), but not by HL. After twelve months, only the WOMAC was a significant predictor (p < 0.001) of physical HRQoL. CONCLUSION: Although subjective satisfaction with the patient's preoperative level of information had a significant effect on the physical HRQoL at one month after THA, the influence of osteoarthritis severity outweighed this effect after twelve months. HL had no direct influence on HRQoL. These results suggest that patient satisfaction, rather than knowledge, predicts HRQoL.

Areal bone mineral density is not associated with femoral stem subsidence in patients younger than 70 years undergoing total hip arthroplasty.

INTRODUCTION: Femoral stem subsidence is a known complication after uncemented total hip arthroplasty (THA). The purpose of this study was to determine the frequency of osteoporosis and to investigate the relationship between areal bone mineral density (aBMD) and subsidence in a cohort of patients younger than 70 years. METHODS: One hundred consecutive patients (age 60 ± 6 years; 52 female, 48 male) undergoing uncemented THA using a collarless press fit femoral stem were retrospectively reviewed. Dual-energy X-ray absorptiometry (DXA) was performed preoperatively at the proximal femur and lumbar spine, and if not feasible at these sites, at the distal radius. DXA results were compared to a cohort of 100 patients ≥ 70 years scheduled for cemented THA. Age, sex, and body mass index (BMI), canal flare index (CFI), and canal fill ratio (CFR) were assessed. Analysis of stem subsidence and migration was performed on standardized, calibrated radiographs obtained postoperatively and at follow-up. RESULTS: The frequency of osteoporosis was considerably lower in the study cohort compared to patients ≥ 70 years (7% vs. 19%, p = 0.02). Illustrated by the high CFR (mean 96 ± 4%) in the mid-stem region, a sufficient press fit was achieved. After a mean follow-up of 7.4 months, the mean stem subsidence was 0.9 ± 0.9 mm. Only two patients had subsidence greater than 3 mm, one of whom was morbidly obese and the other diagnosed with severe osteoporosis. There were no correlations between any of the parameters (CFI, CFR, age, sex, BMI) and femoral stem subsidence. In addition, aBMD T-scores showed no correlations with subsidence. CONCLUSION: aBMD by DXA does not appear to be associated with stem subsidence in patients younger than 70 years and with adequate press fit.

Performance and Hypothetical Impact on Joint Infection Management of the BioFire Joint Infection Panel: a Retrospective Analysis.

Pathogen identification is key in septic arthritis. Culture-based techniques are challenging, especially when patients have been pretreated with antibiotics or when difficult-to-culture bacteria are encountered. The BioFire joint infection assay (BJA) is a multiplex PCR panel which detects 31 of the most prevalent bacterial and fungal pathogens causing septic arthritis. Here, 123 cryoconserved contemporary synovial fluid samples from 120 patients underwent BJA analysis. Results were compared to those of culture-based diagnostics (standard of care [SOC]). Clinical data were collected, and the possible impact of the molecular diagnostic application on patient management was evaluated. Fifteen of 123 synovial fluid cultures grew bacterial pathogens. All on-panel pathogens (9/15) were correctly identified by the BJA. The BJA identified four additional bacterial pathogens in four SOC-negative cases. BJA sensitivity and specificity were 100% (95% confidence interval [CI], 69.2% to 100%) and 100% (95% CI, 96.8% to 100%), respectively. Compared to the SOC, the BJA would have resulted in faster provision of species identification and molecular susceptibility data by 49 h and 99 h, respectively. Clinical data analysis indicates that in BJA-positive cases, faster species ID could have led to timelier optimization of antibiotic therapy. This retrospective study demonstrates high sensitivity and specificity of the BJA to detect on-panel organisms in bacterial arthritis. The usefulness of the BJA in prosthetic-joint infections is limited, as important pathogens (i.e., coagulase negative staphylococci and Cutibacterium acnes) are not covered. Evidence from patient data analysis suggests that the assay might prove valuable for optimizing patient management in acute arthritis related to fastidious organisms or for patients who received antibiotics prior to specimen collection.

Analysis of Three-Dimensional Bone Microarchitecture of the Axis Exposes Pronounced Regional Heterogeneity Associated with Clinical Fracture Patterns.

The odontoid process (dens) of the second cervical vertebra (axis) is prone to fracture. While the importance of its skeletal integrity has been previously noted, representative three-dimensional microarchitecture analyses in humans are not available. This study aimed to determine the bone microarchitecture of the axis using high-resolution quantitative computed tomography (HR-pQCT) and to derive clinical implications for the occurrence and treatment of axis fractures. For initial clinical reference, the apparent density of the axis was determined based on clinical computed tomography (CT) images in patients without and with fractures of the axis. Subsequently, 28 human axes (female 50%) obtained at autopsy were analyzed by HR-pQCT. Analyses were performed in three different regions corresponding to zones I (tip of dens), II (base of dens), and III (corpus axis) of the Anderson and D'Alonzo classification. Lower apparent densities based on clinical CT data were detected in zone II and III compared to zone I in both the group without and with fracture. In the autopsy specimens, cortical thickness and bone volume fraction decreased continuously from zone I to zone III. Trabecular and cortical tissue mineral density was lowest in zone III, with no differences between zones I and II. In conclusion, our clinical and high-resolution ex vivo imaging data highlight a marked regional heterogeneity of bone microarchitecture, with poor cortical and trabecular properties near the dens base. These results may partly explain why zones II and III are at high risk of fracture and osteosynthesis failure.

Cholesteatoma Severely Impacts the Integrity and Bone Material Quality of the Incus.

Cholesteatoma can lead to progressive destruction of the auditory ossicles along with conductive hearing loss but precise data on the microstructural, cellular, and compositional aspects of affected ossicles are not available. Here, we obtained incus specimens from patients who had cholesteatoma with conductive hearing loss. Incudes were evaluated by micro-computed tomography, histomorphometry on undecalcified sections, quantitative backscattered electron imaging, and nanoindentation. Results were compared with two control groups taken from patients with chronic otitis media as well as from skeletally intact donors at autopsy. The porosity of incus specimens was higher in cholesteatoma than in chronic otitis media, along with a higher osteoclast surface per bone surface. Histomorphometric assessment revealed higher osteoid levels and osteocyte numbers in cholesteatoma incudes. Incudes affected by cholesteatoma also showed lower matrix mineralization compared with specimens from healthy controls and chronic otitis media. Furthermore, the modulus-to-hardness ratio was higher in cholesteatoma specimens compared with controls. Taken together, we demonstrated increased porosity along with increased osteoclast indices, impaired matrix mineralization, and altered biomechanical properties as distinct features of the incus in cholesteatoma. Based on our findings, a possible impact of impaired bone quality on conductive hearing loss should be further explored.

Effects of Infantile Hypophosphatasia on Human Dental Tissue.

Hypophosphatasia (HPP) is an inherited, systemic disorder, caused by loss-of-function variants of the ALPL gene encoding the enzyme tissue non-specific alkaline phosphatase (TNSALP). HPP is characterized by low serum TNSALP concentrations associated with defective bone mineralization and increased fracture risk. Dental manifestations have been reported as the exclusive feature (odontohypophosphatasia) and in combination with skeletal complications. Enzyme replacement therapy (asfotase alfa) has been shown to improve respiratory insufficiency and skeletal complications in HPP patients, while its effects on dental status have been understudied to date. In this study, quantitative backscattered electron imaging (qBEI) and histological analysis were performed on teeth from two patients with infantile HPP before and during asfotase alfa treatment and compared to matched healthy control teeth. qBEI and histological methods revealed varying mineralization patterns in cementum and dentin with lower mineralization in HPP. Furthermore, a significantly higher repair cementum thickness was observed in HPP compared to control teeth. Comparison before and during treatment showed minor improvements in mineralization and histological parameters in the patient when normalized to matched control teeth. HPP induces heterogeneous effects on mineralization and morphology of the dental status. Short treatment with asfotase alfa slightly affects mineralization in cementum and dentin. Despite HPP being a rare disease, its mild form occurs at higher prevalence. This study is of high clinical relevance as it expands our knowledge of HPP and dental involvement. Furthermore, it contributes to the understanding of dental tissue treatment, which has hardly been studied so far.

Raman spectroscopy and U-Net deep neural network in antiresorptive drug-related osteonecrosis of the jaw.

OBJECTIVE: Application of an optical method for the identification of antiresorptive drug-related osteonecrosis of the jaw (ARONJ). METHODS: We introduce shifted-excitation Raman difference spectroscopy followed by U-Net deep neural network refinement to determine bone tissue viability. The obtained results are validated through established histological methods. RESULTS: Discrimination of osteonecrosis from physiological tissues was evaluated at 119 distinct measurement loci in 40 surgical specimens from 28 patients. Mean Raman spectra were refined from 11,900 raw spectra, and characteristic peaks were assigned to their respective molecular origin. Then, following principal component and linear discriminant analyses, osteonecrotic lesions were distinguished from physiological tissue entities, such as viable bone, with a sensitivity, specificity, and overall accuracy of 100%. Moreover, bone mineral content, quality, maturity, and crystallinity were quantified, revealing an increased mineral-to-matrix ratio and decreased carbonate-to-phosphate ratio in ARONJ lesions compared to physiological bone. CONCLUSION: The results demonstrate feasibility with high classification accuracy in this collective. The differentiation was determined by the spectral features of the organic and mineral composition of bone. This merely optical, noninvasive technique is a promising candidate to ameliorate both the diagnosis and treatment of ARONJ in the future.

Does Minimally Invasive Surgery Provide Better Clinical or Radiographic Outcomes Than Open Surgery in the Treatment of Hallux Valgus Deformity? A Systematic Review and Meta-analysis.

BACKGROUND: Hallux valgus is the most common foot deformity and affects 23% to 35% of the general population. More than 150 different techniques have been described for surgical correction. Recently, there has been increasing interest in the use of minimally invasive surgery to correct hallux valgus deformities. A variety of studies have been published with differing outcomes regarding minimally invasive surgery. However, most studies lack sufficient power and are small, making it difficult to draw adequate conclusions. A meta-analysis can therefore be helpful to evaluate and compare minimally invasive and open surgery. QUESTIONS/PURPOSES: We performed a systematic review and meta-analysis of randomized controlled trials and prospective controlled studies to answer the following question: Compared with open surgery, does minimally invasive surgery for hallux valgus result in (1) improved American Orthopaedic Foot and Ankle Society (AOFAS) scores and VAS scores for pain, (2) improved radiologic outcomes, (3) fewer complications, or (4) a shorter duration of surgery? METHODS: The systematic review and meta-analysis was conducted according to the guidelines of the Cochrane Handbook for Systematic Reviews of Intervention and the Preferred Reporting Items for Systematic Reviews and Meta-analyses. A search was performed in the PubMed, Embase, Scopus, CINAHL, and CENTRAL databases on May 3, 2022. Studies were eligible if they were randomized controlled or prospective controlled studies that compared minimally invasive surgery and open surgery to treat patients with hallux valgus. We defined minimally invasive surgery as surgery performed through the smallest incision required to perform the procedure accurately, with an incision length of approximately 2 cm at maximum. Open surgery, on the other hand, involves a larger incision and direct visualization of deeper structures. Seven studies (395 feet), consisting of six randomized controlled studies and one prospective comparative study, were included in the qualitative and quantitative data synthesis. There were no differences between the minimally invasive and open surgery groups regarding age, gender, or severity of hallux valgus deformity. Each included study was assessed for the risk of bias using the second version of the Cochrane tool for assessing the risk of bias in randomized trials or by using the Newcastle-Ottawa Scale for comparative studies. Most of the included studies had intermediate quality regarding the risk of bias. We excluded one study from our analysis because of its high risk of bias to avoid serious distortions in the meta-analysis. We performed a sensitivity analysis to confirm that our meta-analysis was robust by including only studies with a low risk of bias. The analyzed endpoints included the AOFAS score (range 0 to 100), where higher scores represent less pain and better function; the minimum clinically important difference on this scale was 29 points. In addition, the VAS score was analyzed, which is based on a pain rating scale (range 0 to 10), with higher scores representing greater pain. Radiologic outcomes included the hallux valgus angle, intermetatarsal angle, and distal metatarsal articular angle. Complications were qualitatively assessed and evaluated for differences. A random-effects model was used if substantial heterogeneity (I 2 > 50%) was found; otherwise, a fixed-effects model was used. RESULTS: We found no clinically important difference between minimally invasive and open surgery in terms of the AOFAS score (88 ± 7 versus 85 ± 8, respectively; mean difference 4 points [95% CI 1 to 6]; p < 0.01). There were no differences between the minimally invasive and open surgery groups in terms of VAS scores (0 ± 0 versus 0 ± 1, respectively; standardized mean difference 0 points [95% CI -1 to 0]; p = 0.08). There were no differences between the minimally invasive and open surgery groups in terms of the hallux valgus angle (12° ± 4° versus 12° ± 4°; mean difference 0 points [95% CI -2 to 2]; p = 0.76). Radiographic measurements of the intermetatarsal angle did not differ between the minimally invasive and open surgery groups (7° ± 2° versus 7° ± 2°; mean difference 0 points [95% CI -1 to 1]; p = 0.69). In addition, there were no differences between the minimally invasive and open surgery groups in terms of the distal metatarsal articular angle (7° ± 4° versus 8° ± 4°; mean difference -1 point [95% CI -4 to 2]; p = 0.28). The qualitative analysis revealed no difference in the frequency or severity of complications between the minimally invasive and the open surgery groups. The minimally invasive and open surgery groups did not differ in terms of the duration of surgery (28 ± 8 minutes versus 40 ± 10 minutes; mean difference -12 minutes [95% CI -25 to 1]; p = 0.06). CONCLUSION: This meta-analysis found that hallux valgus treated with minimally invasive surgery did not result in improved clinical or radiologic outcomes compared with open surgery. Methodologic shortcomings of the source studies in this meta-analysis likely inflated the apparent benefits of minimally invasive surgery, such that in reality it may be inferior to the traditional approach. Given the associated learning curves-during which patients may be harmed by surgeons who are gaining familiarity with a new technique-we are unable to recommend the minimally invasive approach over traditional approaches, in light of the absence of any clinically important benefits identified in this meta-analysis. Future research should ensure studies are methodologically robust using validated clinical and radiologic parameters, as well as patient-reported outcome measures, to assess the long-term outcomes of minimally invasive surgery.

Do Clinical Parameters Reflect Local Bone Metabolism in Heterotopic Ossification After Septic or Aseptic THA?

BACKGROUND: Heterotopic ossification (HO) is a common complication after THA. Although current research primarily focuses on treatment and prevention, little is known about the local bone metabolism of HO and clinical contributing factors. QUESTIONS/PURPOSES: We aimed to assess bone remodeling processes in HO using histomorphometry, focusing on the effects of inflammation and prior NSAID treatment. Specifically, we asked: (1) Are HO specimens taken from patients with periprosthetic joint infection (PJI) more likely to exhibit active bone modeling and remodeling than specimens taken at the time of revision from patients without infection? (2) Do clinical or inflammatory serum and synovial parameters reflect the microstructure of and remodeling in both HO entities? (3) Is NSAID treatment before revision surgery associated with altered local bone mineralization or remodeling properties? METHODS: Between June 2021 and May 2022, we screened 395 patients undergoing revision THA at two tertiary centers in Germany. Of those, we considered all patients with radiographic HO as potentially eligible. Based on that, 21% (83 of 395) were eligible; a further 43 were excluded because of an inability to remove the implant intraoperatively (16 patients), insufficient material (11), comorbidities with a major effect on bone metabolism (10), or bone-specific drugs (six), leaving 10% (40) for analysis in this retrospective, comparative study. HO specimens were collected during aseptic (25 patients: 18 male, seven female, mean age 70 ± 11 years, mean BMI 29 ± 4 kg/m 2 ) and septic (15 patients: 11 male, four female, mean age 69 ± 9 years, mean BMI 32 ± 9 kg/m 2 ) revision THA at a mean of 6 ± 7 years after primary implantation and a mean age of 70 ± 9 years at revision. Septic origin (PJI) was diagnosed based on the 2018 International Consensus Meeting criteria, through a preoperative assessment of serum and synovial parameters. To specify the local bone microstructure, ossification, and cellular bone turnover, we analyzed HO specimens using micro-CT and histomorphometry on undecalcified sections. Data were compared with those of controls, taken from femoral neck trabecular bone (10 patients: five female, five male, mean age 75 ± 6 years, mean BMI 28 ± 4 kg/m 2 ) and osteophytes (10 patients: five female, five male, mean age 70 ± 10 years, mean BMI 29 ± 7 kg/m 2 ). The time between primary implantation and revision (time in situ), HO severity based on the Brooker classification, and serum and synovial markers were correlated with HO microstructure and parameters of cellular bone turnover. In a subgroup of specimens of patients with NSAID treatment before revision, osteoid and bone turnover indices were evaluated and compared a matched cohort of specimens from patients without prior NSAID treatment. RESULTS: Patients with aseptic and septic HO presented with a higher bone volume (BV/TV; aseptic: 0.41 ± 0.15, mean difference 0.20 [95% CI 0.07 to 0.32]; septic: 0.43 ± 0.15, mean difference 0.22 [95% CI 0.08 to 0.36]; femoral neck: 0.21 ± 0.04; both p < 0.001), lower bone mineral density (aseptic: 809 ± 66 mg HA/cm 3 , mean difference -91 mg HA/cm 3 [95% CI -144 to -38]; septic: 789 ± 44 mg HA/cm 3 , mean difference -111 mg HA/cm 3 [95% CI -169 to -53]; femoral neck: 899 ± 20 mg HA/cm 3 ; both p < 0.001), and ongoing bone modeling with endochondral ossification and a higher proportion of woven, immature bone (aseptic: 25% ± 17%, mean difference 25% [95% CI 9% to 41%]; septic: 37% ± 23%, mean difference 36% [95% CI 19% to 54%]; femoral neck: 0.4% ± 0.5%; both p < 0.001) compared with femoral neck specimens. Moreover, bone surfaces were characterized by increased osteoblast and osteoclast indices in both aseptic and septic HO, although a higher density of osteocytes was detected exclusively in septic HO (aseptic: 158 ± 56 1/mm 2 versus septic: 272 ± 48 1/mm 2 , mean difference 114 1/mm 2 [95% CI 65 to 162]; p < 0.001). Compared with osteophytes, microstructure and turnover indices were largely similar in HO. The Brooker class was not associated with any local bone metabolism parameters. The time in situ was negatively associated with bone turnover in aseptic HO specimens (osteoblast surface per bone surface: r = -0.46; p = 0.01; osteoclast surface per bone surface: r = -0.56; p = 0.003). Serum or synovial inflammatory markers were not correlated with local bone turnover in septic HO. Specimens of patients with NSAID treatment before revision surgery had a higher osteoid thickness (10.1 ± 2.1 µm versus 5.5 ± 2.6 µm, mean difference -4.7 µm [95% CI -7.4 to -2.0]; p = 0.001), but there was no difference in other osteoid, structural, or cellular parameters. CONCLUSION: Aseptic and septic HO share phenotypic characteristics in terms of the sustained increase in bone metabolism, although differences in osteocyte and adipocyte numbers suggest distinct homeostatic mechanisms. These results suggest persistent bone modeling or remodeling, with osteoblast and osteoclast indices showing a moderate decline with the time in situ in aseptic HO. Future studies should use longitudinal study designs to correlate our findings with clinical outcomes (such as HO growth or recurrence). In addition, the molecular mechanisms of bone cell involvement during HO formation and growth should be further investigated, which may allow specific therapeutic and preventive interventions. CLINICAL RELEVANCE: To our knowledge, our study is the first to systematically investigate histomorphometric bone metabolism parameters in patients with HO after THA, providing a clinical reference for evaluating modeling and remodeling activity. Routine clinical, serum, and synovial markers are not useful for inferring local bone metabolism.

Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis.

OBJECTIVE: Bone stress injuries (BSIs) are classified in clinical practice as being at low- or high-risk for complication based on the injury location. However, this dichotomous approach has not been sufficiently validated. The purpose of this systematic review was to examine the prognostic role of injury location on return-to-sport (RTS) and treatment complications after BSI of the lower extremity and pelvis. DESIGN: Systematic review and meta-analysis. DATA SOURCES: PubMed, Web of Science, Cochrane CENTRAL and Google Scholar databases were searched from database inception to December 2021. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Peer-reviewed studies that reported site-specific RTS of BSIs in athletes. RESULTS: Seventy-six studies reporting on 2974 BSIs were included. Sixteen studies compared multiple injury sites, and most of these studies (n=11) described the anatomical site of injury as being prognostic for RTS or the rate of treatment complication. Pooled data revealed the longest time to RTS for BSIs of the tarsal navicular (127 days; 95% CI 102 to 151 days) and femoral neck (107 days; 95% CI 79 to 135 days) and shortest duration of time for BSIs of the posteromedial tibial shaft (44 days, 95% CI 27 to 61 days) and fibula (56 days; 95% CI 13 to 100 days). Overall, more than 90% of athletes successfully returned to sport. Treatment complication rate was highest in BSIs of the femoral neck, tarsal navicular, anterior tibial shaft and fifth metatarsal; and lowest in the fibula, pubic bone and posteromedial tibial shaft. CONCLUSION: This systematic review supports that the anatomical site of BSIs influences RTS timelines and the risk of complication. BSIs of the femoral neck, anterior tibial shaft and tarsal navicular are associated with increased rates of complications and more challenging RTS. PROSPERO REGISTRATION NUMBER: CRD42021232351.

Video analysis of Achilles tendon ruptures in professional male football (soccer) reveals underlying injury patterns and provides strategies for injury prevention.

PURPOSE: In professional football (soccer), Achilles tendon ruptures are severe injuries. Video analysis promotes a better understanding of the underlying situational and biomechanical patterns, and provides a roadmap for future research to improve the management and prevention of Achilles tendon ruptures. The purpose of this study was to identify injury patterns contributing to acute Achilles tendon ruptures in professional male football players. METHODS: Professional male football players with an acute Achilles tendon rupture were identified using an online database. For every in-competition injury, the corresponding football match was detected. Video footage of the injury was accessed using Wyscout.com or publicly available video databases. Situational patterns and injury biomechanics of the injury frame were independently analysed by two reviewers using a standardised checklist and a motion analysis software. Finally, consensus was reached to describe the main injury patterns of Achilles tendon ruptures in professional male football players. RESULTS: The search identified video footage of 80 Achilles tendon ruptures in 78 players. Most injuries (94%) occurred through indirect or non-contact mechanisms. The kinematic analysis revealed characteristic joint positions at the time of injury consisting of hip extension, knee extension, ankle dorsiflexion, foot abduction, and foot pronation in most cases. The underlying direction of movement was from flexion to extension (knee) and from plantarflexion to dorsiflexion (ankle). Player actions identified as main injury patterns were stepping back (26%), landing (20%), running/sprinting (18%), jumping (13%), and starting (10%). CONCLUSION: Most Achilles tendon ruptures in professional male football players are closed-chain indirect or non-contact injuries. Sudden loading to the plantarflexor musculotendinous unit remains to be the main component for most cases. By achieving a better understanding of underlying injury mechanisms, this study provides new strategies for the prevention of Achilles tendon ruptures. LEVEL OF EVIDENCE: Level IV.

Bi-planar calibration method for templating of hip joint arthroplasty: phantom study and proof of concept.

PURPOSE: Calibration of radiographs is a critical step in digital templating for hip arthroplasty. Calibration errors of > 1.5% lead to over- or undersizing of the templated implants and may affect logistics and patient safety. Contemporary calibration methods are known to be imprecise with average errors of 6.5% and wide variance. A novel bi-planar radiograph-based calibration method is proposed, and a phantom study was conducted as proof of concept. METHODS: A spherical external calibration marker (ECM) is placed in front of the pubic symphysis of a pelvic bone model at twelve different positions. For each marker position, standard anteroposterior radiographs and four corresponding lateral radiographs with different degrees of rotation (0°-30°) are taken (overall, 60 radiographs). Calibration factors are calculated for an internal calibration marker (ICM) at the centre of the right hip (reference) and the ECM using a novel algorithm. Rotation and marker positions simulate foreseeable use errors and misplacements and aim to test robustness of the method against these errors. RESULTS: ECM calibration factor was 125.9% (range 124.7-127.2), and the mean ICM calibration factor was 126.6% (range 126.2-127.1) ([Formula: see text]). Four images (8.3%) were beyond the 1% error threshold (all with 30° rotation). The mean difference was 0.79% (SD 0.49). CONCLUSION: The bi-planar method precisely predicts the true calibration factor of the hip joint plane under various conditions. In lateral radiographs, rotation of up to 20° did not adversely affect the precision and all images had calibration errors below the threshold for clinical significance.

Classifications of posterior malleolar fractures: a systematic literature review.

INTRODUCTION: Complex ankle fractures frequently involve the posterior malleolus. Many classifications describing posterior malleolar fractures (PMF) exist. The aim of this study was to provide a systematic literature review to outline existing PMF classifications and estimate their accuracy. METHODS: The databases PubMed and Scopus were searched without time limits. Only specific PMF classifications were included; general ankle and/or pilon fracture classifications were excluded. Selection and data extraction was performed by three independent observers. The systematic literature search was performed according to the current criteria of Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). The methodological quality of the included studies was quantified using the modified Coleman score. RESULTS: A total of 110 studies with a total of 12.614 patients were included. Four main classifications were identified: Those describing the size of the posterior malleolar fracture (n = 66), Haraguchi (n = 44), Bartonícek/Rammelt (n = 21) and Mason (n = 12). The quality of the studies was moderate to good with a median Coleman-score of 43.5 (14-79) and a weighted median Coleman-score of 42.5 points. All classifications achieved a substantial to perfect score regarding the inter- and intraobserver reliability, with Mason scoring the lowest in comparison. CONCLUSIONS: None of the reviewed PMF classifications has been able to establish itself decisively in the literature. Most of the classifications are insufficient in terms of a derivable treatment algorithm or a prognosis with regard to outcome. However, as the Bartonícek/Rammelt classification has the greatest potential due to its treatment algorithm, its reliability in combination with consistent predictive values, its usage in clinical practice and research appears advisable.

Radiolucent zones of biodegradable magnesium-based screws in children and adolescents-a radiographic analysis.

INTRODUCTION: Albeit the implantation of magnesium-based biodegradable implants can avoid a second surgery for implant removal, the postoperative occurrence of radiolucent zones around these implants based on corrosion processes has not been previously investigated in children and adolescents. We sought to characterize the distinct temporal and spatial dynamics for magnesium-based implants based on standard clinical routine radiographs. MATERIALS AND METHODS: We retrospectively analyzed 29 patients, treated with magnesium-based compression screws (MAGNEZIX® CS 2.7 mm, CS 3.2 mm, CSC 4.8 mm; Syntellix AG) for fracture fixation, osteotomy, or osteochondral refixation. During a follow-up examination, the clinical and functional status was evaluated. Based on digital radiographs, the ratio of the area of the radiolucent zone and that of the screw was evaluated to assess implant degradation at two follow-up visits (i.e., after 6-8 weeks and 12-24 weeks). RESULTS: In 29 patients (16/29 females, 14.03 ± 2.13 years), a total of 57 implants were evaluated that were used for osteotomy (n = 13, screws n = 26), fracture fixation (n = 9, screws n = 18), or osteochondral refixation (n = 7, screws n = 13). All patients healed without complications and regained full function. Radiolucent zones were observed in 27/29 patients at the first follow-up, with significantly decreased ratios at the second follow-up (2.10 ± 0.55 vs 1.64 ± 0.60, p = 0.0006). Regression analyses were performed to assess the temporal dynamics of radiolucent zones and revealed significant logarithmic developments for the 2.7 mm and 3.2 mm screws, marked by a strong ratio decrease during the first weeks and an almost complete disappearance after approximately 100 days and 200 days, respectively. In contrast, the ceramic-coated 4.8 mm screws presented a significant linear and slower decrease of radiolucent zones. CONCLUSION: Radiolucent zones are a common phenomenon in the course of implant degradation. However, they represent a self-limiting phenomenon. Remarkably, neither implant failure nor affected implant function is noted in this context. Yet, the microstructural changes accompanying the presence of radiolucent zones remain to be analyzed by three-dimensional high-resolution imaging.

Osteoid osteoma in the bones of the hand: a systematic literature review.

INTRODUCTION: Osteoid osteoma (OO) is a common benign bone tumor. OO is observed most frequently in the long bones, especially in the tibia and femur. When occurring in the bones of the hand, OO can be a diagnostic and therapeutic challenge. The aim of this study was to provide a systematic review of occurrence, symptoms, diagnosis and treatment options regarding OO in hand bones. MATERIALS AND METHODS: We performed a systematic review of the literature. All studies from the online databases PubMed and SpringerLink, which reported cases of osteoid osteomas in the bones of the hand, were included. By summarizing the literature, we evaluated the localization within the hand as well as diagnostic and therapeutic options. RESULTS: We included 133 studies reporting 401 cases. OO was mostly common in the phalanges. The diagnosis was mostly made by CT (computed tomography) scan. Most of the OO were treated surgically by open curettage or en bloc resection. CONCLUSIONS: Osteoid osteomas in the bones of the hand are rare and a delayed diagnosis is common. In cases of pain combined with particular symptoms such as nail hypertrophy and swelling OO should be considered. Of the most used imaging methods, CT scans have the highest sensitivity.

Outcome of different reconstruction options using allografts in revision total hip arthroplasty for severe acetabular bone loss: a systematic review and meta-analysis.

INTRODUCTION: Several studies have reported good to excellent outcomes of revision total hip arthroplasty (rTHA) using allografts for treating severe acetabular bone defects. However, precise information on the impact of allograft type and reconstruction method is not available. MATERIAL AND METHODS: Systematic literature search was performed in Medline and Web of Science including patients with acetabular bone loss classified according to the Paprosky classification who underwent rTHA involving the use of allografts. Studies with a minimum follow-up of 2 years published between 1990 and 2021 were included. Kendall correlation was applied to determine the relationship between Paprosky grade and allograft type use. Proportion meta-analyses with 95% confidence interval (CI) were performed to summarize the success of various reconstruction options, including allograft type, fixation method, and reconstruction system. RESULTS: Twenty-seven studies met the inclusion criteria encompassing 1561 cases from 1491 patients with an average age of 64 years (range 22-95). The average follow-up period was 7.9 years (range 2-22). Structural bulk and morselized grafts were used in equal proportions for all Paprosky acetabular defect types. Their use increased significantly with the type of acetabular defect (r = 0.69, p = 0.049). The overall success rate ranged from 61.3 to 98.3% with a random effect pooled estimate of 90% [95% CI 87-93]. Trabecular metal augments (93% [76-98]) and shells (97% [84-99]) provided the highest success rates. However, no significant differences between reconstruction systems, allograft types and fixation methods were observed (p > 0.05 for all comparisons). CONCLUSION: Our findings highlight the use of bulk or morselized allograft for massive bone loss independent of Paprosky classification type and indicate similar good mid- to long-term outcomes of the different acetabular reconstruction options using allografts. CLINICAL TRIAL REGISTRATION: PROSPERO: CRD42020223093.