Artemisinic acid attenuates osteoclast formation and titanium particle-induced osteolysis via inhibition of RANKL-induced ROS accumulation and MAPK and NF-κB signaling pathways.

Periprosthetic osteolysis (PPO) is the most common cause of joint arthroplasty failure. Its progression involves both biological and mechanical factors. Osteoclastogenesis induced by wear from debris-cell interactions, ultimately leading to excessive bone erosion, is considered the primary cause of PPO; therefore, targeting osteoclasts is a promising treatment approach. Currently available drugs have various side effects and limitations. Artemisinic acid (ArA) is a sesquiterpene isolated from the traditional herb Artemisia annua L. that has various pharmacological effects, such as antimalarial, anti-inflammatory, and antioxidant activities. Therefore, this study was aimed at investigating the effect of ArA on osteoclast formation and bone resorption function in vitro, as well as wear particle-induced osteolysis in vivo, and to explore its molecular mechanism of action. Here, we report that ArA inhibits RANKL-stimulated osteoclast formation and function. Mechanistically, ArA suppresses intracellular reactive oxygen species levels by activating the antioxidant response via nuclear factor erythroid-2-related factor 2 (Nrf2) pathway upregulation. It also inhibits the mitogen-activated kinases (MAPK) and nuclear factor-κB (NF-κB) pathways, as well as the transcription and expression of NFATc1 and c-Fos. In vivo experiments demonstrated that ArA reduces osteoclast formation and alleviates titanium particle-induced calvarial osteolysis. Collectively, our study highlights that ArA, with its osteoprotective and antioxidant effects, is a promising therapeutic agent for preventing and treating PPO and other osteoclast-mediated osteolytic diseases.

A New Method to Predict Postoperative Stem Anteversion in Total Hip Arthroplasty for Developmental Dysplasia of the Hip.

BACKGROUND: Preoperative evaluation of femoral anteversion to predict postoperative stem anteversion aids the selection of an appropriate prosthesis and optimizes the combined anteversion in total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The conventional prediction methods are based on the femoral anteversion measurement at the location of the femoral head and/or neck. However, varied differences between femoral anteversion and postoperative stem anteversion were demonstrated. This study investigated the predictive role of a new method based on the principle of sagittal three-point fixation. METHODS: From January 2017 to December 2018, a total of 133 DDH hips that underwent THA were retrospectively analyzed. There were 76 Crowe type I, 27 type II, and 30 type III hips. The single-wedge stem was used in 49 hips, and the double-wedge stem was used in 84 hips. Preoperative native femoral anteversion at the femoral head-neck junction, anterior cortex anteversion at 2 levels of the lesser trochanter, posterior cortex anteversion at 5 levels of the femoral neck, and postoperative stem anteversion were measured using two-dimensional computed tomography. Predictive anteversion by the new method was calculated as the average anteversion formed by the anterior cortex at the lesser trochanter and the posterior cortex at the femoral neck. RESULTS: For hips with different neck heights, different Crowe types, different stem types, or different femoral anteversions, native femoral anteversion showed widely varied differences and correlations with stem anteversion, with differences ranging from -1.27 ± 8.33° to -13.67 ± 9.47° and correlations ranging from 0.122 (p = 0.705, no correlation) to 0.813. Predictive anteversion formed by the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base showed no significant difference with stem anteversion, with less varied differences (0.92 ± 7.52°) and good to excellent correlations (r = 0.826). CONCLUSION: Adopting our new method, predictive anteversion, measured as the average anteversion of the anterior cortex at the lesser trochanter proximal base and posterior cortex 10 mm above the lesser trochanter proximal base, predicted postoperative stem anteversion more reliably than native femoral anteversion.

Free vascularized fibula leads to hallux toe flexion deformity due to ischemic muscle contracture of flexor hallucis longus.

BACKGROUND: This study aimed to investigate the incidence of toe flexion deformity after fibular free flap transplantation and to analyze the etiology of the deformity. METHODS: Fifty patients underwent vascularized fibular free flap transplantation were retrospectively included. Statistical analysis examined correlations between deformity occurrence and resected fibula length and residual distal fibula length using the χ2 test. Doppler ultrasound and anatomical evaluations were conducted. RESULTS: Flexion deformity of the first toe was observed in all patients (100%), exacerbated by ankle dorsiflexion. χ2 test revealed no significant correlation between fibula length, distal residual fibula length, and flexion deformity. Doppler ultrasound revealed elevated echoes and blurred textures in the flexor hallucis longus post-fibular transplantation, while anatomical evaluation confirmed the peroneal artery as its primary nutrient supplier. CONCLUSION: This study reports a 100% incidence of toe flexion deformity post-transplantation. The deformity correlated strongly with ischemic contracture of the flexor hallucis longus.

KLF2/PPARγ axis contributes to trauma-induced heterotopic ossification by regulating mitochondrial dysfunction.

Trauma-induced heterotopic ossification (HO) is a complex disorder after musculoskeletal injury and characterized by aberrant extraskeletal bone formation. Recent studies shed light on critical role of dysregulated osteogenic differentiation in aberrant bone formation. Krupel-like factor 2 (KLF2) and peroxisome proliferator-activated receptor gamma (PPARγ) are master adapter proteins that link cellular responses to osteogenesis; however, their roles and relationships in HO remain elusive. Using a murine burn/tenotomy model in vivo, we identified elevated KLF2 and reduced PPARγ levels in tendon stem/progenitor cells (TSPCs) during trauma-induced HO formation. Both KLF2 inhibition and PPARγ promotion reduced mature HO, whereas the effects of PPARγ promotion were abolished by KLF2 overexpression. Additionally, mitochondrial dysfunction and reactive oxygen species (ROS) production also increased after burn/tenotomy, and improvements in mitochondrial function (ROS scavenger) could alleviate HO formation, but were abolished by KLF2 activation and PPARγ suppression by affecting redox balance. Furthermore, in vitro, we found increased KLF2 and decreased PPARγ levels in osteogenically induced TSPCs. Both KLF2 inhibition and PPARγ promotion relieved osteogenesis by improving mitochondrial function and maintaining redox balance, and effects of PPARγ promotion were abolished by KLF2 overexpression. Our findings suggest that KLF2/PPARγ axis exerts regulatory effects on trauma-induced HO through modulation of mitochondrial dysfunction and ROS production in TSPCs by affecting redox balance. Targeting KLF2/PPARγ axis and mitochondrial dysfunction can represent attractive approaches to therapeutic intervention in trauma-induced HO.

Surgical resection outcomes of post-traumatic elbow heterotopic ossification: multicenter case series at a minimum 5-year follow-up.

BACKGROUND: Heterotopic ossification (HO), a common complication after elbow trauma, causes severe limb disability, Surgical resection is usually performed for post-traumatic elbow HO (PTEHO) to regain mobility. Though it was heavily reported, there has been no long-term (minimum 5-year) follow-up. PATIENTS AND METHODS: 173 patients who underwent PTEHO resection were followed up for minimum 5 years in 4 hospitals between January/2015 and August/2016. Demographics, disease characteristics, preoperative and minimum 5-year assessments were collected. After controlling for potential variables when dividing long-term ROM into <120° and ≥120°, risk factors for ROM recovery to modern functional arc were identified through multivariable regression analysis. RESULTS: Clinically important improvements in ROM of 39°â†’124° were obtained at final follow-up, and 74.6% achieved modern functional arc (≥120°). Mayo Elbow Performance Index (MEPI) had clinically important increases of 69→93 points at final follow-up, and 96.5% reported excellent-to-good. Pain (Numerical Rating Scale, 1.9→0.6 points) and ulnar nerve symptoms were improved. Total complication rate was 15.6%, including new-onset ulnar nerve symptoms (5.8%), HO recurrence with clinical symptoms (6.9%), elbow instability (1.7%), and joint infection (1.2%). Previously reported high body mass index (BMI, p=0.002) and long disease duration (p=0.033) were equally identified as risk factors for not achieving modern functional arc, meanwhile tobacco use (p=0.024) and ankylosed HO (p<0.001) were found to be new risk factors. CONCLUSION: Surgical resection yields satisfactory outcomes for PTEHO at long-term of minimum 5 years. High BMI, tobacco use, long disease duration, and ankylosed HO would negatively affect ROM recovery to modern functional arc (≥120°). LEVEL OF EVIDENCE: Level IV, therapeutic study.

lncRNA MEG3 Promotes Osteogenic Differentiation of Tendon Stem Cells Via the miR-129-5p/TCF4/ß-Catenin Axis and thus Contributes to Trauma-Induced Heterotopic Ossification.

BACKGROUND: Heterotopic ossification (HO) is one of the most intractable conditions following injury to the musculoskeletal system. In recent years, much attention has been paid to the role of lncRNA in musculoskeletal disorders, but its role in HO was still unclear. Therefore, this study attempted to determine the role of lncRNA MEG3 in the formation of post-traumatic HO and further explore the underlying mechanisms. RESULTS: On the basis of high-throughput sequencing and qPCR validation, elevated expression of the lncRNA MEG3 was shown during traumatic HO formation. Accordingly, in vitro experiments demonstrated that lncRNA MEG3 promoted aberrant osteogenic differentiation of tendon-derived stem cells (TDSCs). Mechanical exploration through RNA pulldown, luciferase reporter gene assay and RNA immunoprecipitation assay identified the direct binding relationship between miR-129-5p and MEG3, or miR-129-5p and TCF4. Further rescue experiments confirmed the miR-129-5p/TCF4/ß-catenin axis to be downstream molecular cascade responsible for the osteogenic-motivating effects of MEG3 on the TDSCs. Finally, experiments in a mouse burn/tenotomy model corroborated the promoting effects of MEG3 on the formation of HO through the miR-129-5p/TCF4/ß-catenin axis. CONCLUSIONS: Our study demonstrated that the lncRNA MEG3 promoted osteogenic differentiation of TDSCs and thus the formation of heterotopic ossification, which could be a potential therapeutic target.

Association Between Tranexamic Acid Use and Heterotopic Ossification Prevalence After Elbow Trauma Surgery: A Propensity-Score-Matched Cohort Study.

BACKGROUND: Heterotopic ossification (HO) is a common complication of elbow trauma that can affect limb mobility. Inflammation is an initiating factor for HO formation. Tranexamic acid (TXA) can reduce the inflammatory response after orthopaedic surgery. However, evidence regarding the effectiveness of TXA use for HO prevention after elbow trauma surgery is lacking. METHODS: This retrospective observational propensity-score-matched (PSM) cohort study was conducted from July 1, 2019, to June 30, 2021, at the National Orthopedics Clinical Medical Center, Shanghai, People's Republic of China. A total of 640 patients who underwent surgery following elbow trauma were evaluated. The present study excluded patients with an age of <18 years; those with a history of elbow fracture; those with a central nervous system injury, spinal cord injury, burn injury, or destructive injury; and those who had been lost to follow-up. After 1:1 matching on the basis of sex, age, dominant arm, injury type, open injury, comminuted fracture, ipsilateral trauma, time from injury to surgery, and nonsteroidal anti-inflammatory drug use, the TXA group and the no-TXA group comprised 241 patients each. RESULTS: In the PSM population, the prevalence of HO was 8.71% in the TXA group and 16.18% in the no-TXA group (with rates of 2.07% and 5.80% for clinically important HO, respectively). Logistic regression analyses showed that TXA use was associated with a lower rate of HO (odds ratio [OR], 0.49; 95% CI, 0.28 to 0.86; p = 0.014) than no TXA use, as well as with a lower rate of clinically important HO (OR, 0.34; 95% CI, 0.11 to 0.91; p = 0.044). None of the baseline covariates significantly affected the relationship between TXA use and HO rate (p > 0.05 for all). Sensitivity analyses supported these findings. CONCLUSIONS: TXA prophylaxis may be an appropriate method for the prevention of HO following elbow trauma. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

STING contributes to trauma-induced heterotopic ossification through NLRP3-dependent macrophage pyroptosis.

Trauma-induced heterotopic ossification (HO) is featured by aberrant bone formation at extra-skeletal site. STING is a master adaptor protein linking cellular damage to immune responses, while its role in HO remains elusive. A murine burn/tenotomy model was used to mimic trauma-induced HO in vivo. We demonstrated elevated STING expression in macrophages in inflammatory stage after burn/tenotomy, and STING inhibition significantly alleviated HO formation. Activated NLRP3-dependent macrophage pyroptosis was also found in inflammatory stage after burn/tenotomy. Either STING or NLRP3 suppression reduced mature HO by weakening macrophage pyroptotic inflammation, while protective effects of STING were abolished by NLRP3 overexpression. Further, in vitro, we also found a prominent STING level in pyroptotic BMDMs. STING suppression relieved macrophage pyroptotic inflammation, while abolished by NLRP3 overexpression. Our results reveal that STING poses regulatory effects on trauma-induced HO formation, via modulating NLRP3-dependent macrophage pyroptosis. Targeting STING-NLRP3 axis represents an attractive approach for trauma-induced HO prevention.

A new prognostic nomogram for heterotopic ossification formation after elbow trauma : the Shanghai post-Traumatic Elbow Heterotopic Ossification Prediction (STEHOP) model.

AIMS: Heterotopic ossification (HO) is a common complication after elbow trauma and can cause severe upper limb disability. Although multiple prognostic factors have been reported to be associated with the development of post-traumatic HO, no model has yet been able to combine these predictors more succinctly to convey prognostic information and medical measures to patients. Therefore, this study aimed to identify prognostic factors leading to the formation of HO after surgery for elbow trauma, and to establish and validate a nomogram to predict the probability of HO formation in such particular injuries. METHODS: This multicentre case-control study comprised 200 patients with post-traumatic elbow HO and 229 patients who had elbow trauma but without HO formation between July 2019 and December 2020. Features possibly associated with HO formation were obtained. The least absolute shrinkage and selection operator regression model was used to optimize feature selection. Multivariable logistic regression analysis was applied to build the new nomogram: the Shanghai post-Traumatic Elbow Heterotopic Ossification Prediction model (STEHOP). STEHOP was validated by concordance index (C-index) and calibration plot. Internal validation was conducted using bootstrapping validation. RESULTS: Male sex, obesity, open wound, dislocations, late definitive surgical treatment, and lack of use of non-steroidal anti-inflammatory drugs were identified as adverse predictors and incorporated to construct the STEHOP model. It displayed good discrimination with a C-index of 0.80 (95% confidence interval 0.75 to 0.84). A high C-index value of 0.77 could still be reached in the internal validation. The calibration plot showed good agreement between nomogram prediction and observed outcomes. CONCLUSION: The newly developed STEHOP model is a valid and convenient instrument to predict HO formation after surgery for elbow trauma. It could assist clinicians in counselling patients regarding treatment expectations and therapeutic choices. Cite this article: Bone Joint J 2022;104-B(8):963-971.

Application of a novel osteotomy instrumentation as a substitute tool in total hip arthroplasty.

BACKGROUND: Mechanical failure, power shortage, and inadvertent contamination of the oscillating saw occasionally occurs in actualizing femoral neck osteotomy during total hip arthroplasty (THA); however, no appropriate alternative solution is currently available. This study aimed to introduce a novel osteotomy instrumentation (fretsaw, jig, cable passer hook) as a substitute tool while the oscillating saw was unavailable during THA. METHODS: This study included 40 patients (40 hips) who underwent femoral neck osteotomy during primary THA using the new osteotomy instrumentation (n = 20) and the oscillating saw (n = 20). Clinical data and intraoperative findings of all patients were evaluated. RESULTS: The mean osteotomy time was 22.3 ± 3.1 s (range, 17-30 s) and 29.4 ± 3.7 s (range, 25-39 s) in the oscillating saw group and in the new osteotomy instrumentation group, respectively (P < 0.001). The Harris Hip Score (HHS) improved in both groups; the mean HSS was 82.3 ± 2.5 and 83.3 ± 3.5 in the oscillating saw group and new osteotomy instrumentation group at 6 months after surgery, respectively (P = 0.297). CONCLUSIONS: The original osteotomy instrumentation can be an ideal substitute tool for femoral neck osteotomy in THA, especially when the oscillating saw is unavailable or malfunctioning.

Positive Correlation Between the Femur Neck Shaft and Anteversion Angles: A Retrospective Computed Tomography Analysis in Patients With Developmental Dysplasia of the Hip.

BACKGROUND: This study aimed to explore the anatomical correlation between the femoral neck shaft angle (NSA) and femoral anteversion angle (AA) in patients with developmental dysplasia of the hip based on the Crowe classification and provide a novel method to estimate the femoral AA on anteroposterior pelvic radiographs. METHODS: A total of 208 patients with dysplastic hips who underwent total hip arthroplasty at our institution were retrospectively included. Preoperative physiological AA and NSA were determined via 3-dimensional computed tomography. Linear regressions and Pearson's coefficients were calculated to assess the correlation between the femoral NSA and femoral AA. RESULTS: A total of 416 hips were divided into 5 subgroups: 99 normal, 143 type I, 71 type II, 63 type III, and 40 type IV hips following the Crowe classification. Dysplastic femurs had significantly higher AAs than normal hips (25.2° vs 31.4° vs 33.3° vs 35.5° vs 41.7°). Significant positive correlations between the AA and NSA were observed in normal (r = 0.635), type I (r = 0.700), type II (r = 0.612), and type III (r = 0.638) hips (P < .001); however, no meaningful correlation was observed in type IV hips (r = 0.218, P = .176). CONCLUSION: The NSA and AA correlated positively and significantly in the normal and dysplastic Crowe type I-III hips. The relationship between the NSA and AA indicates torsion of the proximal femur and offers an opportunity for straightforward estimation of AA based on NSA.

Development and analysis of long non-coding RNA-associated competing endogenous RNA network for osteosarcoma metastasis.

BACKGROUND: Osteosarcoma is the primary bone malignant neoplasm that often develops metastasis. Increasing evidences have shown that non-coding RNAs (ncRNAs) relate to the progression of osteosarcoma. However, the ncRNAs' roles in osteosarcoma metastasis are still unknown. METHODS: Differentially expressed (DE) RNAs were identified from Gene Expression Omnibus (GEO) database. Protein-protein interaction (PPI) of DE messenger RNAs (DEmRNAs) was built through STRING database. The target mRNAs and long ncRNAs (lncRNAs) of microRNAs (miRNA) were predicted through miRDB, Targetscan and Genecode databases, which then cross-checked with previously obtained DERNAs to construct competing endogenous RNA (ceRNA) network. All networks were visualized via Cytoscape and the hub RNAs were screened out through Cytoscape plug-in Cytohubba. The gene functional and pathway analyses were performed through DAVID and MirPath databases. The survival analyses of hub RNAs were obtained through Kaplan-Meier (KM) survival curves. RESULTS: Five hundred sixty-four DEmRNAs, 16 DElncRNAs and 22 DEmiRNAs were screened out. GO functional and KEGG pathway analyses showed that DERNAs were significantly associated with tumor metastasis. The ceRNA network including 6 lncRNAs, 55 mRNAs and 20 miRNAs were constructed and the top 10 hub RNAs were obtained. Above all, PI3K/AKT signaling pathway was identified as the most important osteosarcoma metastasis-associated pathway and its hub ceRNA module was constructed. The survival analyses showed that the RNAs in hub ceRNA module closely related to osteosarcoma patients' prognosis. CONCLUSIONS: The current study provided a new perspective on osteosarcoma metastasis. More importantly, the RNAs in hub ceRNA module might act as the novel therapeutic targets and prognostic factors for osteosarcoma patients.

What constitutes a clinically important change in Mayo Elbow Performance Index and range of movement after open elbow arthrolysis?

AIMS: This study aimed to determine the minimal detectable change (MDC), minimal clinically important difference (MCID), and substantial clinical benefit (SCB) under distribution- and anchor-based methods for the Mayo Elbow Performance Index (MEPI) and range of movement (ROM) after open elbow arthrolysis (OEA). We also assessed the proportion of patients who achieved MCID and SCB; and identified the factors associated with achieving MCID. METHODS: A cohort of 265 patients treated by OEA were included. The MEPI and ROM were evaluated at baseline and at two-year follow-up. Distribution-based MDC was calculated with confidence intervals (CIs) reflecting 80% (MDC 80), 90% (MDC 90), and 95% (MDC 95) certainty, and MCID with changes from baseline to follow-up. Anchor-based MCID (anchored to somewhat satisfied) and SCB (very satisfied) were calculated using a five-level Likert satisfaction scale. Multivariate logistic regression of factors affecting MCID achievement was performed. RESULTS: The MDC increased substantially based on selected CIs (MDC 80, MDC 90, and MDC 95), ranging from 5.0 to 7.6 points for the MEPI, and from 8.2° to 12.5° for ROM. The MCID of the MEPI were 8.3 points under distribution-based and 12.2 points under anchor-based methods; distribution- and anchor-based MCID of ROM were 14.1° and 25.0°. The SCB of the MEPI and ROM were 17.3 points and 43.4°, respectively. The proportion of the patients who attained anchor-based MCID for the MEPI and ROM were 74.0% and 94.7%, respectively; furthermore, 64.2% and 86.8% attained SCB. Non-dominant arm (p = 0.022), higher preoperative MEPI rating (p < 0.001), and postoperative visual analogue scale pain score (p < 0.001) were independent predictors of not achieving MCID for the MEPI, while atraumatic causes (p = 0.040) and higher preoperative ROM (p = 0.005) were independent risk factors for ROM. CONCLUSION: In patients undergoing OEA, the MCID for the increased MEPI is 12.2 points and 25° increased ROM. The SCB is 17.3 points and 43.3°, respectively. Future studies using the MEPI and ROM to assess OEA outcomes should report not only statistical significance but also clinical importance. Cite this article: Bone Joint J 2021;103-B(2):366-372.