Joint-dependent response to impact and implications for post-traumatic osteoarthritis

Minimum 5-Year Follow-Up Assessment of Volar Plate Interposition Arthroplasty for Post-Traumatic Osteoarthritis in Proximal Interphalangeal Joints

This is a retrospective study to evaluate the outcome of volar plate interposition arthroplasty for proximal interphalangeal joint post-traumatic osteoarthritis with a minimum 5-year follow-up. We identified patients receiving volar plate interposition arthroplasty for post-traumatic osteoarthritis in proximal interphalangeal joints. The measurements included the numeric pain scale (on a scale of 0-10), the proximal interphalangeal joint active range of motion, the Michigan Hand Outcomes Questionnaire, the perioperative radiograph of the involved digit, proximal interphalangeal joint stability, and pinch strength. Eight patients with a median age of 44 years old (interquartile range (IQR): 29.3-56.8) were included in this study. The median follow-up period was 6.5 years (range of 5-11 years). The median numeric pain scale improved from 5 (IQR: 4.3-6.0) preoperatively to 0 (IQR 0-0.8) at the follow-up evaluation (p = 0.011). All digits demonstrated stability during manual stress testing compared to their noninjured counterparts. The median active proximal interphalangeal joint arc of motion improved from 25° to 55° (p = 0.011). The pinch strength of the fingers on the injured hand was weaker than those on the contralateral hand (2.2 Kg vs. 3.7 Kg, p = 0.012). We suggested that volar plate interposition arthroplasty may be an alternative surgical option for post-traumatic osteoarthritis in the proximal interphalangeal joints.

Prevalence of and factors associated with osteoarthritis and pain in retired Olympians compared with the general population: part 2 - the spine and upper limb

OBJECTIVES

(1) To determine the prevalence of spine and upper limb osteoarthritis (OA) and pain in retired Olympians; (2) identify risk factors associated with their occurrence and (3) compare with a sample of the general population.

METHODS

3357 retired Olympians (44.7 years) and 1735 general population controls (40.5 years) completed a cross-sectional survey. The survey captured demographics, general health, self-reported physician-diagnosed OA, current joint/region pain and significant injury (lasting ≥1 month). Adjusted ORs (aORs) compared retired Olympians and the general population.

RESULTS

Overall, 40% of retired Olympians reported experiencing current joint pain. The prevalence of lumbar spine pain was 19.3% and shoulder pain 7.4%, with lumbar spine and shoulder OA 5.7% and 2.4%, respectively. Injury was associated with increased odds (aOR, 95% CI) of OA and pain at the lumbar spine (OA=5.59, 4.01 to 7.78; pain=4.90, 3.97 to 6.05), cervical spine (OA=17.83, 1.02 to 31.14; pain=9.41, 6.32 to 14.01) and shoulder (OA=4.91, 3.03 to 7.96; pain=6.04, 4.55 to 8.03) in retired Olympians. While the odds of OA did not differ between Olympians and the general population, the odds of lumbar spine pain (1.44, 1.20 to 1.73), the odds of shoulder OA after prior shoulder injury (2.64, 1.01 to 6.90) and the odds of cervical spine OA in female Olympians (2.02, 1.06 to 3.87) were all higher for Olympians compared with controls.

CONCLUSIONS

One in five retired Olympians reported experiencing current lumbar spine pain. Injury was associated with lumbar spine, cervical spine and shoulder OA and pain for Olympians. Although overall OA odds did not differ, after adjustment for recognised risk factors, Olympians were more likely to have lumbar spine pain and shoulder OA after shoulder injury, than the general population.

Prevalence of and factors associated with osteoarthritis and pain in retired Olympians, with comparison to the general population: part 1 – the lower limb

Objectives

This study aims (1) to determine the prevalence of lower limb osteoarthritis (OA) and pain in retired Olympians; (2) to identify factors associated with their occurrence and (3) to compare with a sample of the general population.

Methods

3357 retired Olympians (median 44.7 years) and 1735 general population controls (40.5 years) completed a cross-sectional survey. The survey captured demographics, general health, self-reported physician-diagnosed OA, current joint/region pain and injury history (lasting >1 month). Adjusted OR (aOR) compared retired Olympians with the general population.

Results

The prevalence of (any joint) OA in retired Olympians was 23.2% with the knee most affected (7.4%). Injury was associated with increased odds (aOR, 95% CI) of OA and pain in retired Olympians at the knee (OA=9.40, 6.90 to 12.79; pain=7.32, 5.77 to 9.28), hip (OA=14.30, 8.25 to 24.79; pain=9.76, 6.39 to 14.93) and ankle (OA=9.90, 5.05 to 19.41; pain=5.99, 3.84 to 9.34). Increasing age and obesity were also associated with knee OA and pain. While the odds of OA did not differ between Olympians and the general population, Olympians with prior knee and prior hip injury were more likely than controls with prior injury to experience knee (1.51, 1.03 to 2.21 (Olympians 22.0% vs controls 14.5%)) and hip OA (4.03, 1.10 to 14.85 (Olympians 19.1% vs Controls 11.5%)), respectively.

Conclusions

One in four retired Olympians reported physician-diagnosed OA, with injury associated with knee, hip and ankle OA and pain. Although overall OA odds did not differ, after adjustment for recognised risk factors Olympians were more likely to have knee and hip OA after injury than the general population, suggesting injury is an occupational risk factor for retired Olympians.

Preclinical Models of Elbow Injury and Pathology

The human elbow is a complex joint that is essential for activities of daily living requiring the upper extremities; however, this complexity generates significant challenges when considering its response to injury and management of treatment. The current understanding of elbow injury and pathologies lags behind that of other joints and musculoskeletal tissues. Most research on the elbow joint is mainly focused on the late-stage disease states when irreversible damage has occurred. Consequentially, the specific contribution and relative time course of different elbow tissues in disease progression, as well as optimized approaches for treating such conditions, remains largely unknown. Given the challenge of studying elbow pathologies in humans, preclinical models can serve as ideal alternatives. However, a limited number of preclinical models exist to investigate elbow injury and pathology. This review highlights significant clinical elbow diseases and the preclinical models currently available to recapitulate these diseases, while also providing recommendations for the development of future preclinical models. Overall, this review will serve as a guide for preclinical models studying injuries and pathologies of the elbow, with the long-term goal of developing novel intervention strategies to improve the treatment of elbow diseases in human patients.

Chondrocytes respond both anabolically and catabolically to impact loading generally considered non-injurious

We aimed to determine the longitudinal effects of low-energy (generally considered non-injurious) impact loading on (1) chondrocyte proliferation, (2) chondroprogenitor cell activity, and (3) EGFR signaling. In an in vitro study, we assessed 127 full-thickness, cylindrical osteochondral plugs of bovine cartilage undergoing either single, uniaxial unconfined impact loads with energy densities in the range of 1.5-3.2mJ/mm³ or no impact (controls). We quantified cell responses at two, 24, 48, and 72 h via immunohistochemical labeling of Ki67, Sox9, and pEGFR antibodies. We compared strain, stress, and impact energy density as predictors for mechanotransductive responses from cells, and fit significant correlations using linear regressions. Our study demonstrates that low-energy mechanical impacts (1.5-3.2mJ/mm³) generally stimulate time-dependent anabolic responses in the superficial zone of articular cartilage and catabolic responses in the middle and deep zones. We also found that impact energy density is the most consistent predictor of cell responses to low-energy impact loading. These spatial and temporal changes in chondrocyte behavior result directly from low-energy mechanical impacts, revealing a new level of mechanotransductive sensitivity in chondrocytes not previously appreciated.

Preparation Methods and Clinical Outcomes of Platelet-Rich Plasma for Intra-articular Hip Disorders: A Systematic Review and Meta-analysis of Randomized Clinical Trials

Background:

Despite its increasing use in the management of musculoskeletal conditions, questions remain regarding the preparation methods of platelet-rich plasma (PRP) and its clinical applications for intra-articular hip disorders, including femoroacetabular impingement syndrome (FAIS), labral pathology, and osteoarthritis (OA).

Purpose:

To systematically review and assess the preparation methods and clinical outcomes from randomized clinical trials (RCTs) on the use of PRP for intra-articular hip disorders.

Study Design:

Systematic review; Level of evidence, 2.

Methods:

A systematic review in accordance with the 2009 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines was performed in September 2019. The Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, PubMed, Ovid Medline, and Embase were queried for studies regarding the use of PRP to treat intra-articular hip disorders. Qualifying articles were English-language RCTs describing the use of PRP for intra-articular hip disorders, either as standalone treatment or surgical augmentation. Two authors independently assessed article eligibility. Data pertaining to patient characteristics, indication for treatment, PRP preparation method, follow-up period, and clinical outcomes were extracted. Study results were qualitatively reported and quantitatively compared using meta-analysis when appropriate.

Results:

Seven RCTs met inclusion criteria. Four studies described the use of PRP for hip OA and 3 utilized PRP at arthroscopy for FAIS and labral tears. Outcomes after PRP for OA demonstrated improvement in validated patient-reported outcome measures for up to 1 year; however, pooled effect sizes found no statistically significant difference between PRP and hyaluronic acid (HA) regarding pain visual analog scale scores at short-term (≤2 months; P = .27), midterm (4-6 months; P = .85), or long-term (1 year; P = .42) follow-up. When injected at arthroscopy, 1 study reported improved outcomes, 1 reported no difference in outcomes, and 1 reported worse outcomes compared with controls. The meta-analysis demonstrated no statistically significant difference on the modified Harris Hip Score (mHHS) between PRP and control cohorts at a minimum 1-year follow-up. There were considerable deficiencies and heterogeneity in the reporting of PRP preparation methods for both indications.

Conclusion:

Treatment of OA with PRP demonstrated reductions in pain and improved patient-reported outcomes for up to 1 year. However, there was no statistically significant difference between PRP and HA in pain reduction. Likewise, for FAIS and labral surgery there was no statistically significant difference in mHHS outcomes between patients treated with PRP and controls. Given the limited number of studies and variability in PRP preparations, additional high-quality randomized trials are warranted.

Mechanobiology of Cartilage Impact Via Real-Time Metabolic Imaging

Cartilage loading is important in both structural and biological contexts, with overloading known to cause osteoarthritis (OA). Cellular metabolism, which can be evaluated through the relative measures of glycolysis and oxidative phosphorylation, is important in disease processes across tissues. Details of structural damage coupled with cellular metabolism in cartilage have not been evaluated. Therefore, the aim of this study was to characterize the time- and location-dependent metabolic response to traumatic impact loading in articular cartilage. Cartilage samples from porcine femoral condyles underwent a single traumatic injury that created cracks in most samples. Before and up to 30 min after loading, samples underwent optical metabolic imaging. Optical metabolic imaging measures the fluorescent intensity of byproducts of the two metabolic pathways, flavin adenine dinucleotide for oxidative phosphorylation and nicotinamide adenine dinucleotide ± phosphate for glycolysis, as well as the redox ratio between them. Images were taken at varied distances from the center of the impact. Shortly after impact, fluorescence intensity in both channels decreased, while redox ratio was unchanged. The most dramatic metabolic response was measured closest to the impact center, with suppressed fluorescence in both channels relative to baseline. Redox ratio varied nonlinearly as a function of distance from the impact. Finally, both lower and higher magnitude loading reduced flavin adenine dinucleotide fluorescence, whereas reduced nicotinamide adenine dinucleotide ± phosphate fluorescence was associated only with low strain loads and high contact pressure loads, respectively. In conclusion, this study performed novel analysis of metabolic activity following induction of cartilage damage and demonstrated time-, distance-, and load-dependent response to traumatic impact loading.

Synovial fluid lubricin and hyaluronan are altered in equine osteochondral fragmentation, cartilage impact injury, and full-thickness cartilage defect models

The objectives of this study were to evaluate temporal changes in lubricin, hyaluronan (HA), and HA molecular weight (MW) distributions in three distinct models of equine joint injury affecting the carpal (wrist), tarsal (ankle), and femoropatellar (knee) joints. To establish ranges for lubricin, HA, and HA MW distributions across multiple joints, we first evaluated clinically healthy, high-motion equine joints. Synovial fluid was collected from high-motion joints in horses without clinical signs of joint disease (n = 11 horses, 102 joints) and from research horses undergoing carpal osteochondral fragmentation (n = 8), talar cartilage impact injury (n = 7), and femoral trochlear ridge full-thickness cartilage injury (n = 22) prior to and following arthroscopically induced joint injury. Lubricin and HA concentrations were measured via enzyme-linked immunosorbent assays, and gel electrophoresis was performed to evaluate HA MW distributions. Synovial fluid parameters were analyzed via linear regression models, revealing that lubricin and HA concentrations were conserved across healthy, high-motion joints. Lubricin concentrations increased post-injury in all osteoarthritis models (carpal fragmentation P = .001; talar impact P < .001; femoral trochlear ridge cartilage defect P = .03). Sustained loss of HA was noted post-arthroscopy following carpal osteochondral fragmentation (P < .0001) and talar impact injury (P < .001). Lubricin may be elevated to compensate for the loss of HA and to protect cartilage post-injury. Further investigation into the mechanisms regulating lubricin and HA following joint injury and their effects on joint homeostasis is warranted, including whether lubricin has value as a biomarker for post-traumatic osteoarthritis.

Minimizing Posttraumatic Osteoarthritis After High-Energy Intra-Articular Fracture

This article serves to provide an overview of molecular and surgical interventions to minimize the progression of posttraumatic arthritis following high-energy intra-articular fractures. The roles of cartilage and the microcellular environment are discussed, as well as the response of the joint and cartilage to injury. Molecular therapies, such as glucocorticoids, mesenchymal stem cells, and bisphosphonates, are presented as potential treatments to prevent progression to posttraumatic arthritis. High-energy intra-articular fractures of the elbow, hip, knee, and ankle are discussed, with emphasis on restoring anatomic alignment, articular reduction, and stability of the joint.

Targeting mitochondrial responses to intra-articular fracture to prevent posttraumatic osteoarthritis

We tested whether inhibiting mechanically responsive articular chondrocyte mitochondria after severe traumatic injury and preventing oxidative damage represent a viable paradigm for posttraumatic osteoarthritis (PTOA) prevention. We used a porcine hock intra-articular fracture (IAF) model well suited to human-like surgical techniques and with excellent anatomic similarities to human ankles. After IAF, amobarbital or N-acetylcysteine (NAC) was injected to inhibit chondrocyte electron transport or downstream oxidative stress, respectively. Effects were confirmed via spectrophotometric enzyme assays or glutathione/glutathione disulfide assays and immunohistochemical measures of oxidative stress. Amobarbital or NAC delivered after IAF provided substantial protection against PTOA at 6 months, including maintenance of proteoglycan content, decreased histological disease scores, and normalized chondrocyte metabolic function. These data support the therapeutic potential of targeting chondrocyte metabolism after injury and suggest a strong role for mitochondria in mediating PTOA.

Prevalence and Clinical Implications of Chondral Injuries After Hip Arthroscopic Surgery for Femoroacetabular Impingement Syndrome

BACKGROUND

Studies on the effect of partial- and full-thickness chondral damage of the hip on outcomes and the ability to achieve meaningful clinical outcomes are limited.

PURPOSE

To determine the effect of full- and partial-thickness chondral injuries on 2-year outcomes in patients undergoing hip arthroscopic surgery for femoroacetabular impingement syndrome (FAIS) compared with patients without chondral damage, and to identify significant predictors of achieving the patient acceptable symptomatic state (PASS) and minimal clinically important difference (MCID).

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data from consecutive patients with evidence of chondromalacia at the time of primary hip arthroscopic surgery with routine capsular closure for the treatment of FAIS by a single fellowship-trained surgeon between January 2012 and September 2016 were reviewed. Patients were divided into groups with partial-thickness (grade I-III) or full-thickness (grade IV) chondral defects and matched by age and body mass index (BMI) to patients without chondral injuries. Preoperative and postoperative outcomes were compared among the 3 groups, and a binary logistic regression analysis was utilized to identify significant predictors of achieving the MCID and PASS.

RESULTS

There were 634 patients included in the analysis, with a mean age of 34.5 ± 10.9 years and a mean BMI of 25.2 ± 4.7 kg/m². A total of 493 (77.8%) patients had no evidence of chondral damage, 92 (14.5%) patients had partial-thickness chondral defects, and 49 (7.7%) patients had full-thickness chondral defects. There were statistically significant differences in the Hip Outcome Score (HOS)-Activities of Daily Living, HOS-Sports Subscale, modified Harris Hip Score, pain, and satisfaction (P < .01) among the 3 groups. Patients with grade IV chondromalacia experienced the poorest outcomes and lowest percentage of achieving the PASS. Predictors for achieving any PASS threshold included preoperative alpha angle (odds ratio [OR], 0.96; P = .016), absence of preoperative limping (OR, 7.25; P = .002), absence of preoperative chronic pain (OR, 5.83; P = .019), primary hip arthroscopic surgery (OR, 0.17; P = .050), patients who self-identified as runners (OR, 2.27; P = .037), and Tönnis grade 0 (OR, 2.86; P = .032). Male sex (OR, 2.49; P = .015) was the only predictor of achieving any MCID threshold.

CONCLUSION

Patients with grade IV chondral defects experienced worse functional outcomes, lower satisfaction, and increased pain when compared with both patients without chondral damage or grade I-III chondromalacia at 2-year follow-up. Several predictors were associated with achieving clinically significant function in patients undergoing hip arthroscopic surgery for FAIS.

Evaluation of equine articular cartilage degeneration after mechanical impact injury using cationic contrast-enhanced computed tomography

OBJECTIVE

Cationic agent contrast-enhanced computed tomography (cationic CECT) characterizes articular cartilage ex vivo, however, its capacity to detect post-traumatic injury is unknown. The study objectives were to correlate cationic CECT attenuation with biochemical, mechanical and histological properties of cartilage and morphologic computed tomography (CT) measures of bone, and to determine the ability of cationic CECT to distinguish subtly damaged from normal cartilage in an in vivo equine model.

DESIGN

Mechanical impact injury was initiated in equine femoropatellar joints in vivo to establish subtle cartilage degeneration with site-matched controls. Cationic CECT was performed in vivo (clinical) and postmortem (microCT). Articular cartilage was characterized by glycosaminoglycan (GAG) content, biochemical moduli and histological scores. Bone was characterized by volume density (BV/TV) and trabecular number (Tb.N.), thickness (Tb.Th.) and spacing (Tb.Sp.).

RESULTS

Cationic CECT attenuation (microCT) of cartilage correlated with GAG (r = 0.74, P < 0.0001), compressive modulus (E_eq) (r = 0.79, P < 0.0001) and safranin-O histological score (r = -0.66, P < 0.0001) of cartilage, and correlated with BV/TV (r = 0.37, P = 0.0005), Tb.N. (r = 0.39, P = 0.0003), Tb.Th. (r = 0.28, P = 0.0095) and Tb.Sp. (r = -0.44, P < 0.0001) of bone. Mean [95% CI] cationic CECT attenuation at the impact site (2215 [1987, 2443] Hounsfield Units [HUs]) was lower than site-matched controls (2836 [2490, 3182] HUs, P = 0.036). Clinical cationic CECT attenuation correlated with GAG (r = 0.23, P = 0.049), E_eq (r = 0.26, P = 0.025) and safranin-O histology score (r = -0.32, P = 0.0046).

CONCLUSIONS

Cationic CECT (microCT) reflects articular cartilage properties enabling segregation of subtly degenerated from healthy tissue and also reflects bone morphometric properties on CT. Cationic CECT is capable of characterizing articular cartilage in clinical scanners.

Microfracture provides better clinical results than debridement in the treatment of acute talar osteochondral lesions using arthroscopic assisted fixation of acute ankle fractures

PURPOSE

Ankle arthroscopy is a useful tool for detection and treatment of accompanying intraarticular pathologies in acute ankle fractures. The purpose of this study was to compare the treatment results of talus osteochondral lesions (OLT) with debridement and microfracture in arthroscopy assisted surgery of acute ankle fractures.

METHODS

Eleven consecutive patients who were treated with arthroscopic acute debridement and 14 consecutive patients who were treated with arthroscopic acute microfracture in the treatment of ankle fracture were included in the study. All patients were controlled clinically and radiologically in the postoperative period. Ankle pain was evaluated with the visual analog score (VAS), ankle functions were assessed with American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS), and osteoarthritic changes were analyzed with Van Dijk score.

RESULTS

There was no significant difference between the groups in terms of age, gender, injury side and trauma mechanism (n.s). Mean time to surgery, fracture healing duration, first weight-bearing and full weight-bearing, follow-up period and Van Dijk score were all similar in both groups (n.s). The AOFAS score and VAS activity score were statistically significantly better in the microfracture group (p = 0.044 and p = 0.001).

CONCLUSIONS

The clinical relevance of the present study is to define the acute treatment of the first osteochondral damage that occurred simultaneously with ankle fracture, to improve postoperative functional outcomes and to prevent post-traumatic osteoarthritis. Both debridement and microfracture yield good functional outcomes in the second year of the treatment. Microfracture ensures significantly more successful clinical results than debridement.

LEVEL OF EVIDENCE

Level III.

In vitro study of matrix metalloproteinases 1, 2, 9, 13 and serum amyloid A mRNAs expression in equine fibroblast-like synoviocytes treated with doxycycline

Application of synthetic matrix metalloproteinases (MMPs) inhibitors, such as doxycycline is one of the possible therapeutic options for osteoarthritis. However, little is known about the protective mechanism of doxycycline in equine models on MMPs inhibitors as well as on serum amyloid A (SAA) gene expression. This study investigated the effects of doxycycline on mRNA expression of MMP-1, MMP-2, MMP-9, MMP-13, and SAA of equine fibroblast-like synoviocytes (FLSs). The FLSs were established from synovial fluids of clinically normal metacarpophalangeal joints of 6 skeletally mature horses. The cells were treated with either 10 or 100 μg/mL of doxycycline for 48 h. The mRNA expression of MMP-1, MMP-2, MMP-9, MMP-13, and SAA were assessed using real-time polymerase chain reaction (PCR). Treatment with doxycycline resulted in significantly decreased mRNA expression of MMP-1 in FLSs at both concentrations (P = 0.001). No significant differences were detected among groups for MMP-2, MMP-9, and MMP-13 (P > 0.05). Only a tendency towards a decrease in mRNA expression level of SAA in the presence of doxycycline could be detected. Doxycycline inhibits MMP-1 gene expression at the transcript level. These findings indicate that doxycycline can protect the articular environment through inhibition of MMP-1 at transcript level.

Mitochondrial dysfunction is an acute response of articular chondrocytes to mechanical injury

Mitochondrial (MT) dysfunction is known to occur in chondrocytes isolated from end-stage osteoarthritis (OA) patients, but the role of MT dysfunction in the initiation and early pathogenesis of post-traumatic OA (PTOA) remains unclear. The objective of this study was to investigate chondrocyte MT function immediately following mechanical injury in cartilage, and to determine if the response to injury differed between a weight bearing region (medial femoral condyle; MFC) and a non-weight bearing region (distal patellofemoral groove; PFG) of the same joint. Cartilage was harvested from the MFC and PFG of 10 neonatal bovids, and subjected to injurious compression at varying magnitudes (5-17 MPa, 5-34 GPa/s) using a rapid single-impact model. Chondrocyte MT respiratory function, MT membrane polarity, chondrocyte viability, and cell membrane damage were assessed in situ. Cartilage impact resulted in MT depolarization and impaired MT respiratory function within 2 h of injury. Cartilage from a non-weight bearing region of the joint (PFG) was more sensitive to impact-induced MT dysfunction and chondrocyte death than cartilage from a weight-bearing surface (MFC). Our findings suggest that MT dysfunction is an acute response of chondrocytes to cartilage injury, and that MT may play a key mechanobiological role in the initiation and early pathogenesis of PTOA.

CLINICAL SIGNIFICANCE

Direct therapeutic targeting of MT function in the early post-injury time frame may provide a strategy to block perpetuation of tissue damage and prevent the development of PTOA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:739-750, 2018.

Effect of intra-articular administration of superparamagnetic iron oxide nanoparticles (SPIONs) for MRI assessment of the cartilage barrier in a large animal model

Early diagnosis of cartilage disease at a time when changes are limited to depletion of extracellular matrix components represents an important diagnostic target to reduce patient morbidity. This report is to present proof of concept for nanoparticle dependent cartilage barrier imaging in a large animal model including the use of clinical magnetic resonance imaging (MRI). Conditioned (following matrix depletion) and unconditioned porcine metacarpophalangeal cartilage was evaluated on the basis of fluorophore conjugated 30 nm and 80 nm spherical gold nanoparticle permeation and multiphoton laser scanning and bright field microscopy after autometallographic particle enhancement. Consequently, conditioned and unconditioned joints underwent MRI pre- and post-injection with 12 nm superparamagnetic iron oxide nanoparticles (SPIONs) to evaluate particle permeation in the context of matrix depletion and use of a clinical 1.5 Tesla MRI scanner. To gauge the potential pro-inflammatory effect of intra-articular nanoparticle delivery co-cultures of equine synovium and cartilage tissue were exposed to an escalating dose of SPIONs and IL-6, IL-10, IFN-γ and PGE₂ were assessed in culture media. The chemotactic potential of growth media samples was subsequently assessed in transwell migration assays on isolated equine neutrophils. Results demonstrate an increase in MRI signal following conditioning of porcine joints which suggests that nanoparticle dependent compositional cartilage imaging is feasible. Tissue culture and neutrophil migration assays highlight a dose dependent inflammatory response following SPION exposure which at the imaging dose investigated was not different from controls. The preliminary safety and imaging data support the continued investigation of nanoparticle dependent compositional cartilage imaging. To our knowledge, this is the first report in using SPIONs as intra-articular MRI contrast agent for studying cartilage barrier function, which could potentially lead to a new diagnostic technique for early detection of cartilage disease.

Expression of long non‑coding RNAs in chondrocytes from proximal interphalangeal joints

Osteoarthritis (OA) of hand is a common disease, resulting in disability of the hands. The pathogenesis of hand (H) OA remains to be elucidated, and findings from knee and hip joints cannot be simply applied to HOA. To improve knowledge on the specific biology and pathobiology of HOA, the present study performed bioinformatics analyses to analyze the long non-coding (lnc) RNA expression profile in human chondrocytes of proximal interphalangeal (PIP) finger joints and knee joints. Gene expression data were downloaded from the Gene Expression Omnibus database, and PIP and knee chondrocytes were analyzed (n=3/group). Probes of the Affymetrix Human Gene 2.0 ST Microarray were annotated to obtain information about lncRNA expression profile. Compared with chondrocytes from knee joints, chondrocytes derived from PIP joints had significantly different lncRNA expression profiles, and 1,172 lncRNAs were differentially expressed. Compared with chondrocyte from knee joints, 534 lncRNAs were upregulated and 638 lncRNAs were downregulated in chondrocytes from PIP joints. A co-expression network was constructed to analyze the correlation between lncRNAs and protein-coding genes. Function annotation analyses suggested that protein-coding genes that are co-expressed with lncRNAs are enriched in the biological processes of bone morphogenesis, bone development and cartilage development. In conclusion, the present study demonstrated that chondrocytes derived from PIP joints exhibit a significant difference in lncRNA expression compared with chondrocytes derived from knee joints.

Post-traumatic osteoarthritis of the ankle: A distinct clinical entity requiring new research approaches

The diagnosis of ankle osteoarthritis (OA) is increasing as a result of advancements in non-invasive imaging modalities such as magnetic resonance imaging, improved arthroscopic surgical technology and heightened awareness among clinicians. Unlike OA of the knee, primary or age-related ankle OA is rare, with the majority of ankle OA classified as post-traumatic (PTOA). Ankle trauma, more specifically ankle sprain, is the single most common athletic injury, and no effective therapies are available to prevent or slow progression of PTOA. Despite the high incidence of ankle trauma and OA, ankle-related OA research is sparse, with the majority of clinical and basic studies pertaining to the knee joint. Fundamental differences exist between joints including their structure and molecular composition, response to trauma, susceptibility to OA, clinical manifestations of disease, and response to treatment. Considerable evidence suggests that research findings from knee should not be extrapolated to the ankle, however few ankle-specific preclinical models of PTOA are currently available. The objective of this article is to review the current state of ankle OA investigation, highlighting important differences between the ankle and knee that may limit the extent to which research findings from knee models are applicable to the ankle joint. Considerations for the development of new ankle-specific, clinically relevant animal models are discussed. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:440-453, 2017.

Post-traumatic arthritis: overview on pathogenic mechanisms and role of inflammation

Post-traumatic arthritis (PTA) develops after an acute direct trauma to the joints. PTA causes about 12% of all osteoarthritis cases, and a history of physical trauma may also be found in patients with chronic inflammatory arthritis. Symptoms include swelling, synovial effusion, pain and sometimes intra-articular bleeding. Usually, PTA recoveries spontaneously, but the persistence of symptoms after 6 months may be considered pathological and so-called chronic PTA. A variety of molecular, mechanobiological and cellular events involved in the pathogenesis and the progression of PTA have been identified. The activation of inflammatory mechanisms during the PTA acute phase appears to play a critical role in the chronic disease onset. Human studies and experimental models have revealed that a series of inflammatory mediators are released in synovial fluid immediately after the joint trauma. These molecules have been proposed as markers of disease and as a potential target for the development of specific and preventative interventions. Currently, chronic PTA cannot be prevented, although a large number of agents have been tested in preclinical studies. Given the relevance of inflammatory reaction, anticytokines therapy, in particular the inhibition of interleukin 1 (IL-1), seems to be the most promising strategy. At the present time, intra-articular injection of IL-1 receptor antagonist is the only anticytokine approach that has been used in a human study of PTA. Despite the fact that knowledge in this area has increased in the past years, the identification of more specific disease markers and new therapeutic opportunities are needed.

Chondrocyte cultures from human proximal interphalangeal finger joints

Osteoarthritis (OA) of the hand is a common disease resulting in pain and impaired function. The pathogenesis of hand OA (HOA) is elusive and models to study it have not been described. Chondrocyte culture has been essential to understand cartilage degeneration, which is a hallmark of OA. We investigated the feasibility of human chondrocyte culture derived from proximal interphalangeal (PIP) finger joints. Hyaline cartilage of the PIP and knee joints was obtained from human cadavers. Chondrocytes harvested up to 236 h after death of the donors were viable and expressed chondrocyte-specific genes. Gene expression comparing chondrocytes from PIP and knee joints using Affymetrix GeneChip arrays resulted in a unique PIP-specific gene expression pattern. Genes involved in developmental processes including the WNT pathway were differentially expressed between the joints. These findings suggest that our knowledge on chondrocyte biology derived mainly from knee and hip joints may not apply to chondrocytes of the PIP joints and some of the distinctive features of HOA may be caused by the specific properties of PIP chondrocytes. Chondrocyte culture of PIP cartilage is a novel tool to study cartilage degeneration in HOA. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1569-1575, 2016.

Biological Therapies for Cartilage Lesions in the Hip: A New Horizon

Treatment of hip cartilage disease is challenging, and there is no clear algorithm to address this entity. Biomarkers are arising as promising diagnostic tools because they could play a role in the early assessment of the prearthritic joint and as a prognostic factor before and after treatment. The potential effect of biomarkers may be used to categorize individuals at risk of evolving to severe osteoarthritis, to develop new measures for clinical progression of the disease, and to develop new treatment options for the prevention of osteoarthritis progression. A trend toward a less invasive biological treatment will usher in a new treatment era. With the growth of surgical skills in hip arthroscopy, cartilage restoration techniques are evolving in a fast and exponential manner. Biological and surgical treatments have been proposed to treat these pathologies. Biological treatments include platelet-rich plasma, stem cells or bone marrow aspirate concentration, hyaluronic acid, losartan, and fish oil. Surgical treatments include microfracture alone or augmented, direct repair, autologous chondrocyte implantation, matrix-induced chondrocyte implantation, autologous matrix-induced chondrogenesis, mosaicplasty, osteochondral allograft transplantation, and stem cells implanted in matrix (stem cells in membranes/expanded stem cells). This article reviews new evidence available on treatment options for chondral lesions and early osteoarthritis of the hip. [Orthopedics. 2016; 39(4):e715-e723.].