The development of posttraumatic arthritis after articular fracture

The Relationship Between Intra-articular Fracture Energy and a Patient's Inflammatory Response

OBJECTIVES

Prior studies have demonstrated elevated inflammatory cytokine concentrations in the synovial fluid of articular fracture patients postinjury. Similarly, CT-based fracture energy measurements have been correlated with posttraumatic osteoarthritis risk after pilon fracture. The purpose of this study was to determine the associations between synovial fluid cytokine levels, fracture energy, and overall trauma to the body in articular fracture patients.

METHODS

Acute tibial plateau, tibial plafond, and rotational ankle fracture patients were prospectively enrolled from December 2011 through January 1, 2019. Synovial fluid concentrations of interleukin-1 beta, interleukin-1 receptor antagonist, IL-6, IL-8, IL-10, matrix metallopeptidase-1, MMP-3, and MMP-13 were quantified. Patient CT scans were used to calculate fracture energy. The Injury Severity Score (ISS) was used to relate cytokine levels to whole-body injury severity. Spearman rho correlation coefficients were calculated to assess the relationship between injury severity metrics and synovial fluid cytokine, chemokine, and matrix metallopeptidase concentrations.

RESULTS

Eighty-seven patients were enrolled with 42 had a tibial plateau fractures (OTA/AO 41B1-2, 41B2-14, 41B3-3, 41C1-3, 41C2-4, 41C3-16), 24 patients had a tibial plafond fracture (OTA/AO 43B1-2, 43B2-4, 43B3-5, 43C1-2, 43C2-3, 43C3-8), and 21 had a rotational ankle fracture (OTA/AO 44B1-3, 44B2-3, 44B3-6, 44C1-4, 44C2-5). Fracture energy significantly differed between fracture patterns, with ankle fractures involving substantially less fracture energy (median = 2.92 J) than plafond (10.85 J, P < 0.001) and plateau fractures (13.05 J, P < 0.001). After adjustment for multiple comparisons, MMP-3 was significantly correlated with transformed fracture energy (r = 0.41, 95% confidence interval [CI], 0.22-0.58, P < 0.001), while IL-1β was significantly correlated with the Injury Severity Score (Spearman ρ = 0.31, 95% CI, 0.08-0.49, P = 0.004).

CONCLUSIONS

Synovial fluid MMP-3 concentration was significantly correlated with CT-quantified fracture energy in intra-articular fracture patients. Given that in clinical practice fracture energy tends to correlate with posttraumatic osteoarthritis risk, MMP-3 may warrant further investigation for its role in posttraumatic osteoarthritis development after articular fracture.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Potential Roles of Inflammation on Post-Traumatic Osteoarthritis of the Ankle

Post-traumatic osteoarthritis of the ankle (PTOA) is frequently observed following a debilitating consequence of intra-articular ankle fractures. Numerous risk factors contribute to the pathogenesis of PTOA, including articular incongruity, joint malalignment, and concomitant soft tissue damage. Despite attempts to restore joint anatomy and manage soft tissues to avoid long-term complications after intra-articular ankle fractures, the incidence of PTOA remains markedly elevated. Inflammatory processes triggered by intra-articular ankle fractures have emerged as potential instigators that expedite the progression of PTOA. Injury to the articular cartilage and subchondral bone may lead to the release of inflammatory mediators, which can contribute to cartilage degradation and bone resorption. This study provides a narrative review on the current knowledge concerning the association between inflammation and the development of PTOA following intra-articular ankle fractures. We also discuss novel therapeutic agents that target inflammatory pathways to impede the progression of post-traumatic osteoarthritis after intra-articular ankle fractures. These medication and interventions were summarized within this review article.

Does a rupture of the lateral ankle ligament need to be repaired in supination-adduction type II (OTA/AO 44A2) fractures?

PURPOSE

To evaluate the outcomes of patients with supination-adduction (SAD) type II (OTA/AO 44A2) fractures who had a lateral ankle ligament rupture repaired compared with patients who did not have a lateral ankle ligament repaired using patients who underwent fibula fracture fixation as a control group.

METHODS

A retrospective analysis of all 104 patients diagnosed with SAD type II fractures from January 2011 to December 2020 and managed operatively was performed. The patients were divided into three groups: 32 patients with ruptures of the lateral ligaments that were not repaired (group A), 34 patients with ruptures of the lateral ligaments that were repaired (group B), and 38 patients with fibula fracture fixation acting as the control group (group C). The objective outcomes including radiographic findings, the ankle range of motion, the manual ankle stress tests, and complications were gained from the record of the last time in outpatient clinics. The functional outcomes including the identification of functional ankle instability (IdFAI) scores were collected postoperatively at 12-month intervals to assess clinical outcomes. The Manchester Oxford Foot Questionnaire (MOXFQ) and Karlsson scoring scale were also recorded at the last follow-up.

RESULTS

The mean follow-up of the objective and subjective functional outcomes was 23.4 (range, 13-42) and 76.9 (range, 25-134) months, respectively. There was no significant difference in the radiographic findings, the ankle range of motion and complications between the three groups. All ankles were found to be stable using the manual ankle stress test in both group A and group B. The IdFAI scores showed a significant difference between group A and group B (1.12 ± 1.3 vs 0.35 ± 0.69; p < 0.001) in the first year of follow-up and no significant difference after the first year. No differences were noted in MOXFQ scores or Karlsson scores among the groups.

CONCLUSION

Directly repairing the lateral ligament could minimize the proportion of the first year of postoperative functional ankle instability, although the final stability of the ankle and clinical outcomes were not significantly different in SAD type II fractures.

LEVEL OF EVIDENCE

Level III, retrospective comparative case series.

Standard versus low-dose computed tomography for assessment of acetabular fracture reduction using novel step and gap measurement technique

PURPOSE

Quality of reduction is of paramount importance after acetabular fracture and is best assessed on computed tomography (CT). A recently proposed measurement technique for assessment of step and gap displacement is reproducible but has not been validated. The purpose of this study is to validate a well-established measurement technique against known displacements and to determine if it can be used with low dose CT.

METHODS

Posterior wall acetabular fractures were created in 8 cadaveric hips and fixed at known step and gap displacements. CT was performed at multiple radiation doses for each hip. Four surgeons measured step and gap displacement for each hip at all doses, and the measurements were compared to known values.

RESULTS

There were no significant differences in measurements across surgeons, and all measurements were found to have positive agreement. Measurement error < 1.5 mm was present in 58% of gap measurements and 46% of step measurements. Only for step measurements at a dose of 120 kVp did we observe a statistically significant measurement error. There was a significant difference in step measurements made by those with greater and those with fewer years in practice.

CONCLUSION

Our study suggests this technique is valid and accurate across all doses. This is important as it may reduce the amount of radiation exposure for patients with acetabular fractures.

Comparison of temporary external and percutaneous k-wire fixations for treatment of ankle fracture-dislocations

PURPOSE

Ankle fracture-dislocations are among the most severe injuries, and the use of an external fixator as a recommended fixation method has some disadvantages. The aim of this study was to compare the clinical outcomes and complication rates of external and K-wire fixations in the treatment of ankle fracture dislocations.

METHODS

A total of 67 patients with ankle fracture-dislocations requiring temporary external or percutaneous K-wire fixation were included. The exclusion criteria were pilon fractures, open fractures, and those who required acute open reduction internal fixation (ORIF). The American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a 10-point visual analog scale (VAS) score (range 0-10), and complications before and after the definitive surgery were recorded.

RESULTS

A significant difference between the two groups was not observed for age, sex, affected side, fracture type, smoking status, or diabetes. The average AOFAS scores were 83.2 and 83.3, the median VAS scores were 3 and 3, and the complication rates were 32.4% and 6.7% in the external and K-wire fixation groups, respectively (p = 0.010). However, skin necrosis, re-dislocation of the ankle, surgical wound infection, and posttraumatic ankle osteoarthritis frequency were not significantly different between the groups, except for pin-sites infection (p = 0.036).

CONCLUSION

Ankle fracture-dislocations using percutaneous k-wire fixation showed a low rate of complications and favorable clinical outcomes. This method could be a good alternative treatment option for ankle fracture-dislocations.

Radiological malunion after ankle fractures in older adults : definitions and new thresholds derived from clinical outcome data from the AIM trial

AIMS

The rationale for exacting restoration of skeletal anatomy after unstable ankle fracture is to improve outcomes by reducing complications from malunion; however, current definitions of malunion lack confirmatory clinical evidence.

METHODS

Radiological (absolute radiological measurements aided by computer software) and clinical (clinical interpretation of radiographs) definitions of malunion were compared within the Ankle Injury Management (AIM) trial cohort, including people aged ≥ 60 years with an unstable ankle fracture. Linear regressions were used to explore the relationship between radiological malunion (RM) at six months and changes in function at three years. Function was assessed with the Olerud-Molander Ankle Score (OMAS), with a minimal clinically important difference set as six points, as per the AIM trial. Piecewise linear models were used to investigate new radiological thresholds which better explain symptom impact on ankle function.

RESULTS

Previously described measures of RM and surgeon opinion of clinically significant malunion (CSM) were shown to be related but with important differences. CSM was more strongly related to outcome (-13.9 points on the OMAS; 95% confidence interval (CI) -21.9 to -5.4) than RM (-5.5 points; 95% CI -9.8 to -1.2). Existing malunion thresholds for talar tilt and tibiofibular clear space were shown to be slightly conservative; new thresholds which better explain function were identified (talar tilt > 2.4°; tibiofibular clear space > 6 mm). Based on this new definition the presence of RM had an impact on function, which was statistically significant, but the clinical significance was uncertain (-9.1 points; 95% CI -13.8 to -4.4). In subsequent analysis, RM of a posterior malleolar fracture was shown to have a statistically significant impact on OMAS change scores, but the clinical significance was uncertain (-11.6 points; 95% CI -21.9 to -0.6).

CONCLUSION

These results provide clinical evidence which supports the previously accepted definitions. Further research to investigate more conservative clinical thresholds for malunion is indicated.Cite this article: Bone Jt Open 2022;3(10):841-849.

Minimally Invasive Reduction and Fixation Techniques of Pilon Fractures Based on the Preoperative CT Findings

Tibial plafond fractures are often associated with significant articular cartilage and soft tissue damage. The presence of co-morbidities has been associated with an increased risk of surgical site complications. With improved in surgical techniques and implants, complication rates have declined; however, the overall prognosis often remains poor. The aims of this study were to evaluate the results of innovative minimally invasive reduction and fixation techniques in tibial plafond fractures based on a CT classification and to compare the difference between short and long-term outcomes. Based on preoperative CT findings, fractures were classified into varus, valgus, anterior, posterior, and neutral types. The minimally invasive reduction and fixation techniques depend on type of fracture, size and location of the intraarticular fragments, and degree of comminution of the extra-articular component. Ninety-one pilon fractures (90 patients) underwent minimally invasive reduction and fixation, of which 7 fractures (7.69%), required open reduction because of intraoperative failure to achieve anatomic reduction. Of the 84 fractures that underwent successful minimally invasive reduction and fixation reported, 35 fractures (41.7%) with excellent outcomes, 40 fractures (47.6%) with good outcomes, 6 fractures (7,1%) with fair outcomes, and 3 fractures (3.6%) had poor outcomes for the long-term American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score (follow-up ≥ 60 months). These results prove that minimally invasive treatment is an effective and durable treatment option for intra-articular pilon fractures. We encourage future clinical studies to further refine minimally invasive techniques for pilon fractures to improve outcomes.

A prospective randomized double-blind clinical trial to assess the effects of leukocyte-reduced platelet-rich plasma on pro-inflammatory, degradative, and anabolic biomarkers after closed pilon fractures

Posttraumatic osteoarthritis (PTOA) significantly affects patients with pilon fractures even after adequate anatomical reduction, and treatment strategies targeting the biologic mediators of PTOA are needed. This study was designed to determine the effects of intra-articular injection of platelet-rich plasma (PRP) on synovial fluid (SF) biomarkers for patients undergoing open reduction and internal fixation (ORIF) of pilon fractures. Patients undergoing staged management of pilon fractures were enrolled in a prospective, double-blinded, randomized, and placebo-controlled clinical trial to determine the effects of a single intra-articular injection of leukocyte-reduced PRP on SF biomarkers. Arthrocentesis of the injured and uninjured ankles was performed at the time of external skeletal fixation (ESF) and ORIF. Patients were randomized to receive either autogenous leukocyte-reduced PRP or saline (control) via intra-articular injection into the injured ankle at the time of ESF. SF biomarker concentrations were compared-uninjured, injured pretreatment, and saline-injected or PRP-injected. Eleven patients (PRP, n = 5; saline, n = 6) completed the study. Twenty-one uninjured, and 11 injured pretreatment, five PRP-treated, and six saline-treated SF samples were analyzed. PRP-treated SF contained significantly higher levels of PDGF-AA (p = 0.046) and significantly lower levels of MMP-3 (p = 0.042), MMP-9 (p = 0.009), IL-1β (p = 0.049), IL-6 (p < 0.01), IL-8 (p = 0.048), and PGE2 (p < 0.04). This study provided mechanistic data to suggest that a single intraarticular injection of leukocyte-reduced PRP is associated with anti-inflammatory, anti-degradative, and anabolic responses compared with saline control. These findings provide the impetus for investigating long-term clinical outcomes after PRP injection as an orthobiologic adjunct to ORIF for mitigating the incidence and severity of PTOA after pilon fractures.

Evaluation of the Effect of Selected Physiological Fluid Contaminants on the Mechanical Properties of Selected Medium-Viscosity PMMA Bone Cements

Revision surgeries several years after the implantation of the prosthesis are unfavorable from the patient’s point of view as they expose him to additional discomfort, to risk of complications and are expensive. One of the factors responsible for the aseptic loosening of the prosthesis is the gradual degradation of the cement material as a result of working under considerable loads, in an aggressive environment of the human body. Contaminants present in the surgical field may significantly affect the durability of the bone cement and, consequently, of the entire bone-cement-prosthesis system. The paper presents the results of an analysis of selected mechanical properties of two medium-viscosity bone cements DePuy CMW3 Gentamicin and Heraeus Palamed, for the samples contaminated with saline and blood in the range of 1–10%. The results obtained for compressive strength and modulus of elasticity were subjected to statistical analysis, which estimated the nature of changes in these parameters depending on the amount and type of contamination and their statistical significance.

Plafond Malreduction and Talar Dome Impaction Accelerates Arthrosis After Supination-Adduction Ankle Fracture

BACKGROUND

Supination-adduction (SAD) type II ankle fractures can have medial tibial plafond and talar body impaction. Factors associated with the development of posttraumatic arthritis can be intrinsic to the injury pattern or mitigated by the surgeon. We hypothesize that plafond malreducton and talar body impaction is associated with early posttraumatic arthrosis.

METHODS

A retrospective cohort of skeletally mature patients with SAD ankle fractures at 2 level 1 academic trauma centers who underwent operative fixation were identified. Patients with a minimum of 1-year follow-up were included. The presence of articular impaction identified on CT scan was recorded and the quality of reduction on final intraoperative radiographs was assessed. The primary outcome was radiographic ankle arthrosis (Kellgren-Lawrence 3 or 4), and postoperative complications were documented.

RESULTS

A total of 175 SAD ankle fractures were identified during a 10-year period; 79 patients with 1-year follow-up met inclusion criteria. The majority of injuries resulted from a high-energy mechanism. Articular impaction was present in 73% of injuries, and 23% of all patients had radiographic arthrosis (Kellgren-Lawrence 3 or 4) at final follow-up. Articular malreduction, defined by either a gap or step >2 mm, was significantly associated with development of arthrosis. Early treatment failure, infection, and nonunion was rare in this series.

CONCLUSION

Malreduction of articular impaction in SAD ankle fractures is associated with early posttraumatic arthrosis. Recognition and anatomic restoration with stable fixation of articular impaction appears to mitigate risk of posttraumatic arthrosis. Investigations correlating postoperative and long-term radiographic findings to patient-reported outcomes after operative treatment of SAD ankle fractures are warranted.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Clinical and molecular associations with outcomes at 2 years after acute knee injury: a longitudinal study in the Knee Injury Cohort at the Kennedy (KICK)

BACKGROUND

Joint injury is a major risk factor for osteoarthritis and provides an opportunity to prospectively examine early processes associated with osteoarthritis. We investigated whether predefined baseline demographic and clinical factors, and protein analytes in knee synovial fluid and in plasma or serum, were associated with clinically relevant outcomes at 2 years after knee injury.

METHODS

This longitudinal cohort study recruited individuals aged 16-50 years between Nov 1, 2010, and Nov 28, 2014, across six hospitals and clinics in London, UK. Participants were recruited within 8 weeks of having a clinically significant acute knee injury (effusion and structural injury on MRI), which was typically treated surgically. We measured several predefined clinical variables at baseline (eg, time from injury to sampling, extent and type of joint injury, synovial fluid blood staining, presence of effusion, self-reported sex, age, and BMI), and measured 12 synovial fluid and four plasma or serum biomarkers by immunoassay at baseline and 3 months. The primary outcome was Knee Injury and Osteoarthritis Outcome Score (KOOS4) at 2 years, adjusted for baseline score, assessed in all patients. Linear and logistic regression models adjusting for predefined covariates were used to assess associations between baseline variables and 2-year KOOS4. This study is registered with ClinicalTrials.gov, number NCT02667756.

FINDINGS

We enrolled 150 patients at a median of 17 days (range 1-59, IQR 9-26) after knee injury. 123 (82%) were male, with a median age of 25 years (range 16-50, IQR 21-30). 98 (65%) of 150 participants completed a KOOS4 at 2 (or 3) years after enrolment (50 participants were lost to follow-up and two were withdrawn due to adverse events unrelated to study participation); 77 (51%) participants had all necessary variables available and were included in the core variable adjusted analysis. In the 2-year dataset mean KOOS4 improved from 38 (SD 18) at baseline to 79 (18) at 2 years. Baseline KOOS4, medium-to-large knee effusion, and moderate-to-severe synovial blood staining and their interaction significantly predicted 2-year KOOS4 (n=77; coefficient -20·5, 95% CI -34·8 to -6·18; p=0·0060). The only predefined biomarkers that showed independent associations with 2-year KOOS4 were synovial fluid MCP-1 (n=77; -0·015, 0·027 to -0·004 per change in 1 pg/mL units; p=0·011) and IL-6 (n=77; -0·0005, -0·0009 to -0·0001 per change in 1 pg/mL units; p=0·017). These biomarkers, combined with the interaction of effusion and blood staining, accounted for 39% of outcome variability. Two adverse events occurred that were linked to study participation, both at the time of blood sampling (one presyncopal episode, one tenderness and pain at the site of venepuncture).

INTERPRETATION

The combination of effusion and haemarthrosis was significantly associated with symptomatic outcomes after acute knee injury. The synovial fluid molecular protein response to acute knee injury (best represented by MCP-1 and IL-6) was independently associated with symptomatic outcomes but not with structural outcomes, with the biomarkers overall playing a minor role relative to clinical predictors. The relationship between symptoms and structure after acute knee injury and their apparent dissociation early in this process need to be better understood to make clinical progress.

FUNDING

Versus Arthritis, Kennedy Trust for Rheumatology Research, and NIHR Oxford Biomedical Research Centre.

Initial displacement of the intra-articular surface after articular fracture correlates with PTA in C57BL/6 mice but not "superhealer" MRL/MpJ mice

Posttraumatic arthritis (PTA) occurs commonly after articular fracture and may arise, in part, from joint surface incongruity after injury. MRL/MpJ (MRL) "super-healer" mice are protected from PTA compared to C57BL/6 (B6) mice following articular fracture. However, the relationship between the initial displacement of the articular surface, biologic response, and susceptibility to PTA after fracture remains unclear. The objective of this study was to assess whether joint incongruity after articular fracture, as measured by in vivo micro-computed tomography (microCT), could predict pathomechanisms of PTA in mice. B6 and MRL mice (n = 12/strain) received a closed articular fracture (fx) of the left tibial plateau. Articular incongruity was quantified as bone surface deviations (BSD) for each in vivo microCT scan obtained from pre-fx to 8 weeks post-fx, followed by histologic assessment of arthritis. Serum concentrations of bone formation (PINP) and bone resorption (CTX-I) biomarkers were quantified longitudinally. Both strains showed increases in surface incongruity over time, as measured by increases in BSD. In B6 mice, acute surface incongruity was significantly correlated to the severity of PTA (R ²  = 0.988; p = .0006), but not in MRL mice (R ²  = 0.224; p = .220). PINP concentrations significantly decreased immediately post-fx in B6 mice (p = .023) but not in MRL mice, indicating higher bone synthesis in MRL mice. MRL/MpJ mice demonstrate a unique biologic response to articular fracture such that the observed articular bone surface displacement does not correlate with the severity of subsequent PTA. Clinical Relevance: Identifying therapies to enhance acute biologic repair following articular fracture may mitigate the risk of articular surface displacement for PTA.

3D modelling of tibial plateau fractures: Variability in fracture location and characteristics across Schatzker fracture types

INTRODUCTION

Numerous classifications have been developed to assess tibial plateau fractures (TPF). Of these, the Schatzker system is the most widely reported in the literature yet this system is limited in its characterisation of morphological fracture features underlying the fracture location. The purpose of this study was to compare 3D morphological features of TPFs across different Schatzker types.

METHODS

This study retrospectively analysed preoperative TPF imaging data to reconstruct 3D models of the fractures. Ninety-one fractures (29 female, 62 male) were analysed and classified using Schatzker. Fracture location across Schatzker types was compared based on division of the articular surface into six 'zones'. Additionally, morphological characteristics of the fractures were compared based on fracture type, including; the number, volume and shape of the fragments.

RESULTS

Schatzker II, IV and VI fractures were most common, making up 41%, 16% and 20%, respectively. Type II fractures commonly involved both the lateral and central aspect of the tibial plateau, similarly, type IV fractures incorporated the lateral condyle in most cases. Considering the morphological metrics, statistically significant differences were observed between Schatzker types for the number of; total, articular, cortical and volumetrically significant (all P < 0.001) fragments along with the volume of both primary (P < 0.001) and secondary (P = 0.02) fragments.

DISCUSSION

Assessment of underlying fracture characteristics in addition to fracture location can serve to provide greater detail relating to fracture morphology, which has the potential to assist with both surgical decision making and assessment of postoperative outcomes. Incorporating this information as part of a hierarchical or multifactorial framework for classifying fractures may help distinguish subtle differences between fracture types that are classifiable using the most current systems.

The Current UK Consensus on the Management of Weber B and Posterior Ankle Fractures: A Questionnaire Study as Part of the Acute Management of Ankle Fractures (AUGMENT) Audit

Ankle fractures are common conditions which are associated with significant morbidity when managed incorrectly. With the incidence due to triple by 2030, standards of practice were created by the British Orthopaedic Association and the British Orthopaedic Foot and Ankle Society to ensure optimal treatment. In spite of this, anecdotally there is still a variation in practice and therefore a questionnaire study was designed to explore clinician decision-making around Weber B and Posterior Malleolus ankle fractures. Five scenarios explored management regarding minimally and grossly displaced injuries, as well as the use of further imaging. The questionnaires were distributed via AUGMENT collaborators at their sites and at the British Orthopaedic Foot and Ankle Society congress 2018. About 315 questionnaires were completed and included in analysis. For Weber B injuries, overall there was a consensus across all respondents with minimally displaced and grossly displaced fractures being treated conservatively and operatively respectively. For Posterior Malleolus injuries, there was variation in practice between Foot and Ankle specialists and their non-Foot and Ankle colleagues. Computed tomography (CT) was more likely to be used to assess these injuries by specialists (97.50 vs 69.79%) and these injuries were more likely to be treated operatively across the board. This study identified key variation in practice of the management of Posterior Malleolar ankle fractures, including the use of imaging to further define the anatomy and the decision to operate. Foot and Ankle surgeons were more likely to organize CT scans and to surgically manage these injures.

Supination Adduction Ankle Fractures Are Associated With Arthritis and Poor Outcomes

OBJECTIVE

To compare complications and functional outcomes between supination adduction type II (SAD) injuries and torsional ankle injuries (TAI).

DESIGN

Retrospective cohort.

SETTING

Level 1 trauma center.

PATIENTS AND METHODS

Patients (n = 1531) treated for ankle fractures (OTA/AO 43B or 44) over 16 years were identified. The most recent 200 consecutive adult patients treated for TAI (OTA/AO 44, not SAD) served as controls.

MAIN OUTCOME MEASURES

Complications, unplanned secondary procedures, and patient-reported functional outcome scores, as measured by the Foot Function Index and Short Musculoskeletal Function Assessment.

RESULTS

Sixty-five patients with SAD injuries (4.2%) were included. They were younger (43.2 vs. 47.7 years, P = 0.08) and more commonly involved in a motorized collision, (58.5% vs. 29.0%) and more often multiply injured: other orthopaedic injuries (66.2% vs. 31.0%) and other nonorthopaedic injuries (40.0% vs. 7.5%, all P < 0.001 vs. TAI). Overall complication and unplanned secondary procedure rates were not different between groups. Those with a SAD injury had more posttraumatic arthrosis (80.0% vs. 40.9%, P = 0.004), but no differences were noted in infection, wound healing, malunion, or nonunion. The mean functional outcome scores were worse for SAD patients over 6 years after injury among all the Foot Function Index and Short Musculoskeletal Function Assessment categories; however, these differences were not significant.

CONCLUSIONS

SAD injuries represented 4.2% of all ankle fractures, occurring in younger patients through higher-energy mechanisms and more often associated with polytrauma. Despite 80% of SAD patients developing posttraumatic arthrosis, secondary procedures were not more common, and functional outcomes after a SAD injury were not different from TAI.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

A Novel Strategy to Enhance Microfracture Treatment With Stromal Cell-Derived Factor-1 in a Rat Model

Background

Microfracture is one of the most widely used techniques for the repair of articular cartilage. However, microfracture often results in filling of the chondral defect with fibrocartilage, which exhibits poor durability and sub-optimal mechanical properties. Stromal cell-derived factor-1 (SDF-1) is a potent chemoattractant for mesenchymal stem cells (MSCs) and is expressed at high levels in bone marrow adjacent to developing cartilage during endochondral bone formation. Integrating SDF-1 into an implantable collagen scaffold may provide a chondro-conductive and chondro-inductive milieu via chemotaxis of MSCs and promotion of chondrogenic differentiation, facilitating more robust hyaline cartilage formation following microfracture.

Objective

This work aimed to confirm the chemoattractive properties of SDF-1 in vitro and develop a one-step method for incorporating SDF-1 in vivo to enhance cartilage repair using a rat osteochondral defect model.

Methods

Bone marrow-derived MSCs (BMSCs) were harvested from the femurs of Sprague–Dawley rats and cultured in low-glucose Dulbecco’s modified Eagle’s medium containing 10% fetal bovine serum, with the medium changed every 3 days. Passage 1 MSCs were analyzed by flow cytometry with an S3 Cell Sorter (Bio-Rad). In vitro cell migration assays were performed on MSCs by labeling cells with carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE; Bio-Rad). For the microfracture model, a 1.6-mm-diameter osteochondral defect was created in the femoral trochleae of 20 Sprague–Dawley rats bilaterally until bone marrow spillage was seen under saline irrigation. One knee was chosen at random to receive implantation of the scaffold, and the contralateral knee was left unfilled as an empty control. Type I collagen scaffolds (Kensey Nash) were coated with either gelatin only or gelatin and SDF-1 using a dip coating process. The rats received implantation of either a gelatin-only scaffold (N = 10) or gelatin-and-SDF-1 scaffold (N = 10) at the site of the microfracture. Femurs were collected for histological analyses at 4- and 8-week time points post-operatively, and sections were stained with Safranin O/Fast Green. The samples were graded blindly by two observers using the Modified O’Driscoll score, a validated scoring system for chondral repair. A minimum of 10 separate grading scores were made per sample and averaged. Quantitative comparisons of cell migration in vitro were performed with one-way ANOVA. Cartilage repair in vivo was also compared among groups with one-way ANOVA, and the results were presented as mean ± standard deviation, with P-values < 0.05 considered as statistically significant.

Results

MSC migration showed a dose–response relationship with SDF-1, with an optimal dosage for chemotaxis between 10 and 100 ng/ml. After scaffold implantation, the SDF-1-treated group demonstrated complete filling of the cartilage defect with mature cartilage tissue, exhibiting strong proteoglycan content, smooth borders, and good incorporation into marginal cartilage. Modified O’Driscoll scores after 8 weeks showed a significant improvement of cartilage repair in the SDF-1 group relative to the empty control group (P < 0.01), with a trend toward improvement when compared with the gelatin-only-scaffold group (P < 0.1). No significant differences in scores were found between the empty defect group and gelatin-only group.

Conclusion

In this study, we demonstrated a simple method for improving the quality of cartilage defect repair in a rat model of microfracture. We confirmed the chemotactic properties of SDF-1 on rat MSCs and found an optimized dosage range for chemotaxis between 10 and 100 ng/ml. Furthermore, we demonstrated a strategy to incorporate SDF-1 into gelatin–collagen I scaffolds in vivo at the site of an osteochondral defect. SDF-1-treated defects displayed robust hyaline cartilage resurfacing of the defect with minimal fibrous tissue, in contrast to the empty control group. The results of the in vitro and in vivo studies together suggest that SDF-1-mediated signaling may significantly improve the quality of cartilage regeneration in an osteochondral defect.

Characterization and Validation of Arg286 Residue of IL-1RAcP as a Potential Drug Target for Osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis and the fastest growing cause of chronic disability in the world. Formation of the ternary IL-1β /IL-1R1/IL-1RAcP protein complex and its downstream signaling has been implicated in osteoarthritis pathology. Current OA therapeutic approaches target either the cytokine IL-1β or the primary receptor IL-1RI but do not exploit the potential of the secondary receptor IL-1RAcP. Our previous work implicated the Arg286 residue of IL-1RAcP as a key mediator of complex formation. Molecular modeling confirmed Arg286 as a high-energy mediator of the ternary IL-1β complex architecture and interaction network. Anti-IL-1RAcP monoclonal antibodies (mAb) targeting the Arg286 residue were created and were shown to effectively reduce the influx of inflammatory cells to damaged joints in a mouse model of osteoarthritis. Inhibitory peptides based on the native sequence of IL-1RAcP were prepared and examined for efficacy at disrupting the complex formation. The most potent peptide inhibitor had an IC50 value of 304 pM in a pull-down model of complex formation, and reduced IL-1β signaling in a cell model by 90% at 2 μM. Overall, therapies that target the Arg286 region surface of IL-1RAcP, and disrupt subsequent interactions with subunits, have the potential to serve as next generation treatments for osteoarthritis.

Posttraumatic osteoarthritis: what have we learned to advance osteoarthritis?

PURPOSE OF REVIEW

Current thinking in the study of posttraumatic osteoarthritis (PTOA) is overviewed: the osteoarthritis which follows acute joint injury. The review particularly highlights important publications in the last 18 months, also reflecting on key older literature, in terms of what have we have we learned and have yet to learn from PTOA, which can advance the osteoarthritis field as a whole.

RECENT FINDINGS

PTOA is a mechanically driven disease, giving insight into mechanical drivers for osteoarthritis. A mechanosensitive molecular tissue injury response (which includes activation of pain, degradative and also repair pathways) is triggered by acute joint injury and seen in osteoarthritis. Imaging features of PTOA are highly similar to osteoarthritis, arguing against it being a different phenotype. The inflammatory pathways activated by injury contribute to early joint symptoms. However, later structural changes appear to be dissociated from traditional measures of synovial inflammation.

SUMMARY

PTOA remains an important niche in which to understand processes underlying osteoarthritis and seek interventional targets. Whether PTOA has true molecular or clinical differences to osteoarthritis as a whole remains to be understood. This knowledge is important for a field where animal modelling of the disease relies heavily on the link between injury and osteoarthritis.

Longitudinal changes in lower limb joint loading up to two years following tibial plateau fracture

BACKGROUND

Tibial plateau fractures are one of the most common intra-articular fractures resulting from high or low energy impact trauma. Few studies have assessed postoperative outcomes of these fractures with respect to changes in knee joint loading post-surgery. This gait analysis study compared lower limb joint loading up to two years post-surgery.

METHODS

Twenty patients (range 27-67 years; 9:11(male:female)) were treated with open reduction internal fixation and instructed to weight bear as tolerated immediately following surgery. Joint loading at the hip, knee and ankle were assessed at six time points post-operatively up to two years. Gait analyses were performed at each time point and a musculoskeletal model was used to compute external joint moments for the lower limb.

RESULTS

Hip flexion and extension (P = <0.001, P = <0.001), knee flexion (P = 0.014) and ankle plantarflexion moments (P = <0.001) showed significant increases with time. The hip flexion moment increased between six months and one year (mean difference = 0.16 Nm/kg) but did not increase thereafter (mean difference = 0.01 Nm/kg). Knee flexion and extension, and ankle plantarflexion moments increased up to six months (mean difference = 0.22 Nm/kg, 0.14 Nm/kg, 0.80 Nm/kg, respectively), but no further differences were seen with time from six months postoperative.

DISCUSSION

The greatest changes in joint loads were observed at the hip and ankle within the first six months, likely a result of mechanical adaptations attempting to account for limited motion at the knee. Knee joint loading plateaued beyond six months suggesting functional outcomes are largely reliant on postoperative management within the initial three months while the bone is healing.

Intra-articular depletion of macrophages increases acute synovitis and alters macrophage polarity in the injured mouse knee

OBJECTIVE

Acute synovial inflammation following joint trauma is associated with posttraumatic arthritis. Synovial macrophages have been implicated in degenerative changes. In this study, we sought to elucidate the role of intra-articular macrophages in the acute inflammatory response to fracture in the mouse knee.

METHOD

A closed articular fracture was induced in two models of synovial macrophage depletion: genetically-modified MaFIA mice administered AP20187 to induce programmed macrophage apoptosis, and wild-type C57BL/6 mice administered clodronate liposomes, both via intra-articular injection. Synovial inflammation, bone morphology, and levels of F4/80+ macrophages, NOS2+ M1 macrophages, and CD206+ M2 macrophages were quantified 7 days after fracture using histology and micro-computed tomography.

RESULTS

Intra-articular macrophage depletion with joint injury did not reduce acute synovitis or the number of synovial macrophages 7 days after fracture in either macrophage-depleted MaFIA mice or in clodronate-treated C57BL/6 mice. In macrophage-depleted MaFIA mice, macrophage polarity shifted to a dominance of M1 macrophages and a reduction of M2 macrophages in the synovial stroma, indicating a shift in M1/M2 macrophage ratio in the joint following injury. Interestingly, MaFIA mice depleted 2 days prior to fracture demonstrated increased synovitis (P = 0.003), reduced bone mineral density (P = 0.0004), higher levels of M1 macrophages (P = 0.013), and lower levels of M2 macrophages (not statistically significant, P=0.084) compared to control-treated MaFIA mice.

CONCLUSION

Our findings indicate that macrophages play a critical immunomodulatory role in the acute inflammatory response surrounding joint injury and suggest that inhibition of macrophage function can have prominent effects on joint inflammation and bone homeostasis after joint trauma.

Posttraumatic Arthritis After Intra-Articular Distal Femur and Proximal Tibia Fractures

Posttraumatic arthritis (PTA) is a form of joint degeneration that occurs after physical trauma to a synovial joint. Development of PTA is multifactorial and results from mechanical damage at the time of trauma, a cell-mediated inflammatory response, and abnormal articulation due to persistent malalignment or joint instability. Although some risk factors may be unavoidable, preventing the development of PTA of the knee after intra-articular fracture (IAF) requires restoring anatomic articulation and alignment. Reconstruction with total knee arthroplasty is the treatment of choice for PTA and may be a useful primary treatment for IAF in some.

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.

Do Spatiotemporal Gait Parameters Improve After Pilon Fracture in Patients Who Use the Intrepid Dynamic Exoskeletal Orthosis?

BACKGROUND

Pilon fractures are high-energy fractures about the ankle observed commonly in both civilian and military trauma populations. Despite surgical management, outcomes are predictably poorly characterized by functional deficits secondary to pain and stiffness. The Intrepid Dynamic Exoskeletal Orthosis (IDEO) and Return-to-Run clinical pathway were initially designed to treat military service members after complex battlefield lower extremity injuries. The IDEO has been used to treat nonbattlefield injuries, but, to our knowledge, it has not been studied specifically among patients with pilon fractures. By studying the use of the IDEO in this patient population, we hope to learn how it might improve ambulation in the community, relieve pain, and return patients to work to better identify patients who might benefit from its use.

QUESTIONS/PURPOSES

The purpose of this study was to determine whether the IDEO would improve gait parameters including velocity, cadence, stride length, and single-leg stance duration in patients with pilon fractures. Our secondary endpoints of interest were reductions in pain and return to duty.

METHODS

A prospectively collected database of all active-duty IDEO users at a single institution was queried for all patients using the IDEO after a pilon fracture. Patients were included if they were using the IDEO after sustaining a surgically treated pilon fracture and had exhausted all nonoperative therapies. Exclusions were patients with an incomplete gait analysis at the two study time points. Seven patients meeting these criteria were identified. Three-dimensional gait analysis was performed two times: first wearing shoes at a self-selected speed and second after a custom-made IDEO was fabricated for the patient and completion of the Return-to-Run pathway. Patients reported their average pain while ambulating using a numeric rating scale. Gait variables of interest were velocity, cadence, stride length, and single stance time. Return to military service was assessed through the military medical record. To return to duty, a service-specific physical readiness test must be completed.

RESULTS

Median gait velocity improved from 1.1 (interquartile range [IQR], 0.9-1.2) to 1.3 m/s (IQR, 1.2-1.5; p = 0.01). All other variables did not change: cadence 98.4 (IQR, 93.0-107.2) to 104.5 steps/min (IQR, 103.0-109.0; p = 0.13), affected stride length 1.3 (IQR, 1.0-1.4 m) to 1.4 m (IQR, 1.3-1.6 m; p = 0.07), and affected single stance 0.42 (IQR, 0.41-0.47) to 0.43 (IQR, 0.42-0.44; p = 0.80). Pain did not change between time points: 3 (IQR, 2-3) to 2.5 (IQR, 1-3.5; p = 0.90). Three of seven patients returned to duty.

CONCLUSIONS

At self-selected walking speeds, we observed no improvements in gait parameters or pain after application of the IDEO that would likely be considered clinically important, and so the device is unlikely to be worth the cost in this setting. It is possible that for higher demand users such as elite athletes, the IDEO could have a role after severe lower extremity trauma; however, this must be considered speculative until or unless proven in future studies.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Effect of Surgical Insertion and Proinflammatory Cytokines on Osteochondral Allograft Survival and Metabolism

Objective To investigate the responses of refrigerated osteochondral allograft cartilage (OCA) and fresh cartilage (FC), including cell survival and metabolism, to surgical impaction and proinflammatory cytokines. Design Osteochondral plugs (8 mm diameter) were harvested from prolonged-refrigerated (14-28 days) and fresh (≤24 hours postmortem) human femoral hemicondyles and subjected to a 0.2 N s pneumatic impaction impulse. Cartilage explants were removed from subchondral bone and randomized to 1 of 6 treatment groups: (1) Unimpacted control (UIC), (2) Impacted control (IC), (3) Impacted + interleukin (IL)-1β (0.1 ng/mL), (4) Impacted + IL-1β (0.1 ng/mL) + IL-6, (5) Impacted + IL-1β (10 ng/mL), and (6) Impacted + IL-1β (10 ng/mL) + IL-6. Samples were measured for cell viability, histology, and proteoglycan (PG) content at days 0, 2, 7, and 14 of culture. Results In UIC, cell viability was indistinguishable between OCA and FC and remained constant. Impaction alone decreased cell viability by 30% ( P < 0.01) in the OCA superficial layer and by 26% ( P < 0.01) in the entire tissue, but did not affect viability in FC. Cytokine addition did not further influence cell viability. Impaction alone did not affect PG synthesis. Addition of cytokines to impacted tissue decreased PG synthesis by ~3-fold in both tissue types in comparison with corresponding impacted controls ( P < 0.01). Throughout 2-week culture, PG release remained stable in all FC groups, but peaked at day 14 in OCA cartilage subjected to cytokines. Conclusions Mechanical impaction, mimicking surgical insertion, has a more profound effect on cell viability in OCA than in FC. Addition of proinflammatory cytokines further decreases OCA tissue metabolism and integrity.

A systematic literature review of tibial plateau fractures: What classifications are used and how reliable and useful are they?

INTRODUCTION

Classification systems such as the Schatzker and AO/OTA have been proposed for standardised assessment of tibial plateau fractures and to guide clinical decision making. However, there has been no comprehensive literature review of all classification systems for tibial plateau fractures, including assessment of their reliability. The aim of this systematic review was to identify and appraise previously established classification systems for tibial plateau fractures and determine their reliability for fracture classification.

METHODS

Six databases were searched from inception until October 2016. Classification systems for tibial plateau fractures were identified. No restriction was placed on imaging modality (plain film X-ray, CT, MRI). Data synthesis was performed to identify common features of the systems, their prevalence within the literature and studies of intra and inter-rater reliability of fracture classification using Kappa coefficient (κ).

RESULTS

Thirty-eight classification systems were identified, five of which were a sub-classification of a single fracture type from a previous tool. The Schatzker and AO/OTA classification systems were the most commonly reported. Of the tools identified only five have been tested for inter and intra-observer reliability (Schatzker, AO/OTA, Duparc, Hohl and Luo). Reliability of more simplistic classification systems, such as that by Luo et al. (three-column) was typically high (intra-κ = 0.67-0.81, inter-κ = 0.71-0.87), but with the disadvantage of providing less information on fracture patterns and morphology. Intra and inter-observer reliability using plain film X-ray was frequently moderate (κ = 0.40-0.60), with 2D and 3D CT typically improving reliability of classification. Only 11 of the 32 complete classification systems identified association of fracture classification with clinical outcome.

DISCUSSION

Frequently used systems for classification of tibial plateau fractures display moderate intra and inter-observer reliability. More sophisticated imaging modalities such as 2D and 3D CT typically improve reliability estimates. Using fracture classification based on imaging findings to predict clinical outcome was not a commonly reported goal of newly developed systems. More detailed assessment of fracture patterns and morphology, in conjunction with information on surgical fixation, may be desirable for predicting outcomes and to guide clinical decision making.

The Ankle Injury Management (AIM) trial: a pragmatic, multicentre, equivalence randomised controlled trial and economic evaluation comparing close contact casting with open surgical reduction and internal fixation in the treatment of unstable ankle fractures in patients aged over 60 years

BACKGROUND

Close contact casting (CCC) may offer an alternative to open reduction and internal fixation (ORIF) surgery for unstable ankle fractures in older adults.

OBJECTIVES

We aimed to (1) determine if CCC for unstable ankle fractures in adults aged over 60 years resulted in equivalent clinical outcome compared with ORIF, (2) estimate cost-effectiveness to the NHS and society and (3) explore participant experiences.

DESIGN

A pragmatic, multicentre, equivalence randomised controlled trial incorporating health economic evaluation and qualitative study.

SETTING

Trauma and orthopaedic departments of 24 NHS hospitals.

PARTICIPANTS

Adults aged over 60 years with unstable ankle fracture. Those with serious limb or concomitant disease or substantial cognitive impairment were excluded.

INTERVENTIONS

CCC was conducted under anaesthetic in theatre by surgeons who attended training. ORIF was as per local practice. Participants were randomised in 1 : 1 allocation via remote telephone randomisation. Sequence generation was by random block size, with stratification by centre and fracture pattern.

MAIN OUTCOME MEASURES

Follow-up was conducted at 6 weeks and, by blinded outcome assessors, at 6 months after randomisation. The primary outcome was the Olerud-Molander Ankle Score (OMAS), a patient-reported assessment of ankle function, at 6 months. Secondary outcomes were quality of life (as measured by the European Quality of Life 5-Dimensions, Short Form questionnaire-12 items), pain, ankle range of motion and mobility (as measured by the timed up and go test), patient satisfaction and radiological measures. In accordance with equivalence trial US Food and Drug Administration guidance, primary analysis was per protocol.

RESULTS

We recruited 620 participants, 95 from the pilot and 525 from the multicentre phase, between June 2010 and November 2013. The majority of participants, 579 out of 620 (93%), received the allocated treatment; 52 out of 275 (19%) who received CCC later converted to ORIF because of loss of fracture reduction. CCC resulted in equivalent ankle function compared with ORIF at 6 months {OMAS 64.5 points [standard deviation (SD) 22.4 points] vs. OMAS 66.0 points (SD 21.1 points); mean difference -0.65 points, 95% confidence interval (CI) -3.98 to 2.68 points; standardised effect size -0.04, 95% CI -0.23 to 0.15}. There were no differences in quality of life, ankle motion, pain, mobility and patient satisfaction. Infection and/or wound problems were more common with ORIF [29/298 (10%) vs. 4/275 (1%)], as were additional operating theatre procedures [17/298 (6%) vs. 3/275 (1%)]. Malunion was more common with CCC [38/249 (15%) vs. 8/274 (3%); p < 0.001]. Malleolar non-union was lower in the ORIF group [lateral: 0/274 (0%) vs. 8/248 (3%); p = 0.002; medial: 3/274 (1%) vs. 18/248 (7%); p < 0.001]. During the trial, CCC showed modest mean cost savings [NHS mean difference -£644 (95% CI -£1390 to £76); society mean difference -£683 (95% CI -£1851 to £536)]. Estimates showed some imprecision. Incremental quality-adjusted life-years following CCC were no different from ORIF. Over common willingness-to-pay thresholds, the probability that CCC was cost-effective was very high (> 95% from NHS perspective and 85% from societal perspective). Experiences of treatments were similar; both groups endured the impact of fracture, uncertainty regarding future function and the need for further interventions.

LIMITATIONS

Assessors at 6 weeks were necessarily not blinded. The learning-effect analysis was inconclusive because of limited CCC applications per surgeon.

CONCLUSIONS

CCC provides a clinically equivalent outcome to ORIF at reduced cost to the NHS and to society at 6 months.

FUTURE WORK

Longer-term follow-up of trial participants is under way to address concerns over potential later complications or additional procedures and their potential to impact on ankle function. Further study of the patient factors, radiological fracture patterns and outcomes, treatment responses and prognosis would also contribute to understanding the treatment pathway.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN04180738.

FUNDING

The National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 75. See the NIHR Journals Library website for further project information. This report was developed in association with the National Institute for Health Research Oxford Biomedical Research Unit funding scheme. The pilot phase was funded by the AO Research Foundation.

Predictors of osteoarthritis following operative treatment of medial tibial plateau fractures

PURPOSE

To determine factors influencing the development of posttraumatic osteoarthritis (OA) following medial tibial plateau fractures and to evaluate concomitant injuries associated with these fractures.

MATERIALS AND METHODS

A chart review of patients with operatively treated medial tibial plateau fractures admitted to our Level I trauma centre from 2002 to 2008 was performed. Of 63 patients, 41 participated in a clinical and radiographic examination. The mean age was 47 years (range 16-78) and the mean follow-up time was 7.6 (range 4.7-11.7) years. All patients had preoperative computed tomography (CT) scans and postoperative radiographs. At the end of follow-up, standing radiographs, mechanical axis, and CT scans were evaluated.

RESULTS

Of the 41 patients, 24 had no or mild (Kellgren-Lawrence grade 0-2) OA and 17 had severe (grade 3-4) OA. Initial articular depression measured from preoperative CT scans was a significant predictor of OA (median 1.8mm vs 4.5mm, p=0.009). Fracture line extension to the lateral plateau (p=0.68) or fracture comminution (p=0.21) had no effect on the development of posttraumatic OA, nor did articular depression at the end of follow-up (p=0.68) measured from CT scans. Mechanical axis >4° of varus and ≥2mm articular depression or step-off were associated with worse WOMAC pain scores, but did not affect other functional outcome scores. Six patients (10%) had permanent peroneal nerve dysfunction. Ten patients (16%) required LCL reconstruction and nine (14%) ACL avulsions were treated at the time of fracture stabilisation.

CONCLUSIONS

The amount of articular depression measured from preoperative CT scans seems to predict the development of posttraumatic OA, probably reflecting the severity of chondral injury at the time of fracture. Restoration of mechanical axis and articular congruence are important in achieving a good clinical outcome.

DAMPs Synergize with Cytokines or Fibronectin Fragment on Inducing Chondrolysis but Lose Effect When Acting Alone

OBJECTIVE AND DESIGN

To investigate whether endogenous damage-associated molecular patterns (DAMPs) or alarmins originated from mitochondria or nucleus stimulates inflammatory response in articular chondrocytes to cause chondrolysis which leads to cartilage degradation featured in posttraumatic osteoarthritis (PTOA).

MATERIALS

Primary cultures of bovine or human chondrocytes isolated from cartilage of weight-bearing joints.

TREATMENT

Chondrocytes were subjected to mitochondrial DAMPs (MTDs) or HMGB1, a nuclear DAMP (NuD), with or without the presence of an N-terminal 29 kDa fibronectin fragment (Fn-f) or proinflammatory cytokines (IL-1β and TNF-α). Injured cartilage-conditioned culturing medium containing a mixture of DAMPs was employed as a control. After 24 hrs, the protein expression of cartilage degrading metalloproteinases and iNOS in culture medium or cell lysates was examined with Western blotting, respectively.

RESULTS

HMGB1 was synergized with IL-1β in upregulating expression of MMP-3, MMP-13, ADAMTS-5, ADAM-8, and iNOS. Moreover, a moderate synergistic effect was detected between HMGB1 and Fn-f or between MTDs and TNF-α on MMP-3 expression. However, when acting alone, MTDs or HMGB1 did not upregulate cartilage degrading enzymes or iNOS.

CONCLUSION

MTDs or HMGB1 could only stimulate inflammatory response in chondrocytes with the presence of cytokines or Fn-f.

Acute Molecular Changes in Synovial Fluid Following Human Knee Injury: Association With Early Clinical Outcomes

Objective

To investigate whether molecules found to be up‐regulated within hours of surgical joint destabilization in the mouse are also elevated in the analogous human setting of acute knee injury, how this molecular response varies between individuals, and whether it is related to patient‐reported outcomes in the 3 months after injury.

Methods

Seven candidate molecules were analyzed in blood and synovial fluid (SF) from 150 participants with recent structural knee injury at baseline (<8 weeks from injury) and in blood at 14 days and 3 months following baseline. Knee Injury and Osteoarthritis Outcome Score 4 (KOOS₄) was obtained at baseline and 3 months. Patient and control samples were compared using Meso Scale Discovery platform assays or enzyme‐linked immunosorbent assay.

Results

Six of the 7 molecules were significantly elevated in human SF immediately after injury: interleukin‐6 (IL‐6), monocyte chemotactic protein 1, matrix metalloproteinase 3 (MMP‐3), tissue inhibitor of metalloproteinases 1 (TIMP‐1), activin A, and tumor necrosis factor–stimulated gene 6 (TSG‐6). There was low‐to‐moderate correlation with blood measurements. Three of the 6 molecules were significantly associated with baseline KOOS₄ (those with higher SF IL‐6, TIMP‐1, or TSG‐6 had lower KOOS₄). These 3 molecules, MMP‐3, and activin A were all significantly associated with greater improvement in KOOS₄ over 3 months, after adjustment for other relevant factors. Of these, IL‐6 alone significantly accounted for the molecular contribution to baseline KOOS₄ and change in KOOS₄ over 3 months.

Conclusion

Our findings validate relevant human biomarkers of tissue injury identified in a mouse model. Analysis of SF rather than blood more accurately reflects this response. The response is associated with patient‐reported outcomes over this early period, with SF IL‐6 acting as a single representative marker. Longitudinal outcomes will determine if these molecules are biomarkers of subsequent disease risk.

Regulated in Development and DNA Damage Response 1 Deficiency Impairs Autophagy and Mitochondrial Biogenesis in Articular Cartilage and Increases the Severity of Experimental Osteoarthritis

OBJECTIVE

Regulated in development and DNA damage response 1 (REDD1) is an endogenous inhibitor of mechanistic target of rapamycin (mTOR) that regulates cellular stress responses. REDD1 expression is decreased in aged and osteoarthritic (OA) cartilage, and it regulates mTOR signaling and autophagy in articular chondrocytes in vitro. This study was undertaken to investigate the effects of REDD1 deletion in vivo using a mouse model of experimental OA.

METHODS

OA severity was histologically assessed in 4-month-old wild-type and REDD1^-/- mice subjected to surgical destabilization of the medial meniscus (DMM). Chondrocyte autophagy, apoptosis, mitochondrial content, and expression of mitochondrial biogenesis markers were determined in cartilage and cultured chondrocytes from wild-type and REDD1^-/- mice.

RESULTS

REDD1 deficiency increased the severity of changes in cartilage, menisci, subchondral bone, and synovium in the DMM model of OA. Chondrocyte death was increased in the cartilage of REDD1^-/- mice and in cultured REDD1^-/- mouse chondrocytes under oxidative stress conditions. Expression of key autophagy markers (microtubule-associated protein 1A/1B light chain 3 and autophagy protein 5) was markedly reduced in cartilage from REDD1^-/- mice and in cultured human and mouse chondrocytes with REDD1 depletion. Mitochondrial content, ATP levels, and expression of the mitochondrial biogenesis markers peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and transcription factor A, mitochondrial (TFAM) were also decreased in REDD1-deficient chondrocytes. REDD1 was required for AMP-activated protein kinase-induced PGC-1α in chondrocytes.

CONCLUSION

Our findings suggest that REDD1 is a key mediator of cartilage homeostasis through regulation of autophagy and mitochondrial biogenesis and that REDD1 deficiency exacerbates the severity of injury-induced OA.

Increased risk of early and medium-term revision after post-fracture total knee arthroplasty

Background and purpose - Total knee arthroplasty (TKA) due to posttraumatic fracture osteoarthritis (PTFA) may be associated with inferior prosthesis survival. This study is the first registry-based study solely addressing this issue. Both indications and predictors for revision were identified. Patients and methods - 52,518 primary TKAs performed between 1997 and 2013 were retrieved from the Danish Knee Arthroplasty Register (DKR). 1,421 TKAs were inserted due to PTFA and 51,097 due to primary osteoarthritis (OA). Short-term (< 1 year), medium-term (1-5 years), and long-term (> 5 years) implant survival were analyzed using Kaplan-Meier analysis and Cox regression after age stratification (< 50, 50-70, and >70 years). In addition, indications for revision and characteristics of TKA patients with subsequent revision were determined. Results - During the first 5 years, TKAs inserted due to PTFA had a higher risk of revision than OA (with adjusted hazard ratio ranging from 1.5 to 2.4 between age categories). After 5 years, no significant differences in the risk of revision were seen between the groups. Infection and aseptic loosening were the most common causes of revision in both groups, but TKA instability was a more frequent indication for revision in the PTFA group. In both groups, the revision rates were higher with younger age and extended duration of primary surgery. Interpretation - We found an increased risk of early and medium-term revision of TKAs inserted due to previous fractures in the distal femur and/or proximal tibia. Predictors of revision such as age <50 years and extended duration of primary surgery were identified, and revision due to instability occurred more frequently in TKAs performed due to previous fractures.

Regulated in Development and DNA Damage Response 1 Deficiency Impairs Autophagy and Mitochondrial Biogenesis in Articular Cartilage and Increases the Severity of Experimental Osteoarthritis

OBJECTIVE

Regulated in development and DNA damage response 1 (REDD1) is an endogenous inhibitor of mechanistic target of rapamycin (mTOR) that regulates cellular stress responses. REDD1 expression is decreased in aged and osteoarthritic (OA) cartilage, and it regulates mTOR signaling and autophagy in articular chondrocytes in vitro. This study was undertaken to investigate the effects of REDD1 deletion in vivo using a mouse model of experimental OA.

METHODS

OA severity was histologically assessed in 4-month-old wild-type and REDD1^-/- mice subjected to surgical destabilization of the medial meniscus (DMM). Chondrocyte autophagy, apoptosis, mitochondrial content, and expression of mitochondrial biogenesis markers were determined in cartilage and cultured chondrocytes from wild-type and REDD1^-/- mice.

RESULTS

REDD1 deficiency increased the severity of changes in cartilage, menisci, subchondral bone, and synovium in the DMM model of OA. Chondrocyte death was increased in the cartilage of REDD1^-/- mice and in cultured REDD1^-/- mouse chondrocytes under oxidative stress conditions. Expression of key autophagy markers (microtubule-associated protein 1A/1B light chain 3 and autophagy protein 5) was markedly reduced in cartilage from REDD1^-/- mice and in cultured human and mouse chondrocytes with REDD1 depletion. Mitochondrial content, ATP levels, and expression of the mitochondrial biogenesis markers peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and transcription factor A, mitochondrial (TFAM) were also decreased in REDD1-deficient chondrocytes. REDD1 was required for AMP-activated protein kinase-induced PGC-1α in chondrocytes.

CONCLUSION

Our findings suggest that REDD1 is a key mediator of cartilage homeostasis through regulation of autophagy and mitochondrial biogenesis and that REDD1 deficiency exacerbates the severity of injury-induced OA.

Effect of Calcaneus Fracture Gap Without Step-Off on Stress Distribution Across the Subtalar Joint

BACKGROUND

Subtalar arthritis is a common consequence following calcaneal fracture, and its development is related to the severity of the fracture. Previous calcaneal fracture models have demonstrated altered contact characteristics when a step-off is created in the posterior facet articular surface. Changes in posterior facet contact characteristics have not been previously characterized for calcaneal fracture gap without step-off.

METHODS

The contact characteristics (peak pressure, area of contact, and centroid of pressure) of the posterior facet of the subtalar joint were determined in 6 cadaveric specimens. After creating a calcaneal fracture to simulate a Sanders type II fracture, the contact characteristics were determined with the posterior facet anatomically reduced followed by an incremental increase in fracture gap displacement of 2, 3, and 5 mm without a step-off of the articular surface.

RESULTS

Peak pressure on the medial fragment was significantly less with a 5-mm gap compared to a 2- or 3-mm gap, or reduced. On the lateral fragment, the peak pressure was significantly increased with a 5-mm gap compared to a 2- or 3-mm gap. Contact area significantly changed with increased gap.

CONCLUSION

In this study, there were no significant differences in contact characteristics between a <3-mm gap and an anatomically reduced fracture, conceding the study limitations including limiting axial loading to 50% of donor body weight.

CLINICAL RELEVANCE

A small amount of articular incongruity without a step-off can be tolerated by the subtalar joint, in contrast to articular incongruity with a step-off present.

Predictive value of clinical scoring and simplified gait analysis for acetabulum fractures

BACKGROUND

Fractures of the acetabulum show a high, long-term complication rate. The aim of the present study was to determine the predictive value of clinical scoring and standardized, simplified gait analysis on the outcome after these fractures.

METHODS

Forty-one patients with acetabular fractures treated between 2008 and 2013 and available, standardized video recorded aftercare were identified from a prospective database. A visual gait score was used to determine the patients walking abilities 6-m postoperatively. Clinical (Merle d'Aubigne and Postel score, visual analogue scale pain, EQ5d) and radiological scoring (Kellgren-Lawrence score, postoperative computed tomography, and Matta classification) were used to perform correlation and multivariate regression analysis.

RESULTS

The average patient age was 48 y (range, 15-82 y), six female patients were included in the study. Mean follow-up was 1.6 y (range, 1-2 y). Moderate correlation between the gait score and outcome (versus EQ5d: r_s = 0.477; versus Merle d'Aubigne: r_s = 0.444; versus Kellgren-Lawrence: r_s = -0.533), as well as high correlation between the Merle d'Aubigne score and outcome were seen (versus EQ5d: r_s = 0.575; versus Merle d'Aubigne: r_s = 0.776; versus Kellgren-Lawrence: r_s = -0.419). Using a multivariate regression model, the 6 m gait score (B = -0.299; P < 0.05) and early osteoarthritis development (B = 1.026; P < 0.05) were determined as predictors of final osteoarthritis. A good fit of the regression model was seen (R² = 904).

CONCLUSIONS

Easy and available clinical scoring (gait score/Merle d'Aubigne) can predict short-term radiological and functional outcome after acetabular fractures with sufficient accuracy. Decisions on further treatment and interventions could be based on simplified gait analysis.

The posttraumatic stiff elbow: an update

Posttraumatic elbow stiffness is a disabling condition that remains challenging to treat despite improvement of our understanding of the pathogenesis of posttraumatic contractures and new treatment regimens. This review provides an update and overview of the etiology of posttraumatic elbow stiffness, its classification, evaluation, nonoperative and operative treatment, and postoperative management.

Objective Structured Assessments of Technical Skills (OSATS) Does Not Assess the Quality of the Surgical Result Effectively

BACKGROUND

Performance assessment in skills training is ideally based on objective, reliable, and clinically relevant indicators of success. The Objective Structured Assessment of Technical Skill (OSATS) is a reliable and valid tool that has been increasingly used in orthopaedic skills training. It uses a global rating approach to structure expert evaluation of technical skills with the experts working from a list of operative competencies that are each rated on a 5-point Likert scale anchored by behavioral descriptors. Given the observational nature of its scoring, the OSATS might not effectively assess the quality of surgical results.

QUESTIONS/PURPOSES

(1) Does OSATS scoring in an intraarticular fracture reduction training exercise correlate with the quality of the reduction? (2) Does OSATS scoring in a cadaveric extraarticular fracture fixation exercise correlate with the mechanical integrity of the fixation?

METHODS

Orthopaedic residents at the University of Iowa (six postgraduate year [PGY]-1s) and at the University of Minnesota (seven PGY-1s and eight PGY-2s) undertook a skills training exercise that involved reducing a simulated intraarticular fracture under fluoroscopic guidance. Iowa residents participated three times during 1 month, and Minnesota residents participated twice with 1 month between their two sessions. A fellowship-trained orthopaedic traumatologist rated each performance using a modified OSATS scoring scheme. The quality of the articular reduction obtained was then directly measured. Regression analysis was performed between OSATS scores and two metrics of articular reduction quality: articular surface deviation and estimated contact stress. Another skills training exercise involved fixing a simulated distal radius fracture in a cadaveric specimen. Thirty residents, distributed across four PGY classes (PGY-2 and PGY-3, n = 8 each; PGY-4 and PGY-5, n = 7 each), simultaneously completed the exercise at individual stations. One of three faculty hand surgeons independently scored each performance using a validated OSATS scoring system. The mechanical integrity of each fixation construct was then assessed in a materials testing machine. Regression analysis was performed between OSATS scores and two metrics of fixation integrity: stiffness and failure load.

RESULTS

In the intraarticular fracture model, OSATS scores did not correlate with articular reduction quality (maximum surface deviations: R = 0.17, p = 0.25; maximum contact stress: R = 0.22, p = 0.13). Similarly in the cadaveric extraarticular fracture model, OSATS scores did not correlate with the integrity of the mechanical fixation (stiffness: R = 0.10, p = 0.60; failure load: R = 0.30, p = 0.10).

CONCLUSIONS

OSATS scoring methods do not effectively assess the quality of the surgical result. Efforts must be made to incorporate assessment metrics that reflect the quality of the surgical result.

CLINICAL RELEVANCE

New objective, reliable, and clinically relevant measures of the quality of the surgical result obtained by a trainee are urgently needed. For intraarticular fracture reduction and extraarticular fracture fixation, direct physical measurement of reduction quality and of mechanical integrity of fixation, respectively, meet this need.

Integration of Stem Cell to Chondrocyte-Derived Cartilage Matrix in Healthy and Osteoarthritic States in the Presence of Hydroxyapatite Nanoparticles

We investigated the effectiveness of integrating tissue engineered cartilage derived from human bone marrow derived stem cells (HBMSCs) to healthy as well as osteoarthritic cartilage mimics using hydroxyapatite (HA) nanoparticles immersed within a hydrogel substrate. Healthy and diseased engineered cartilage from human chondrocytes (cultured in agar gels) were integrated with human bone marrow stem cell (HBMSC)-derived cartilaginous engineered matrix with and without HA, and evaluated after 28 days of growth. HBMSCs were seeded within photopolymerizable poly (ethylene glycol) diacrylate (PEGDA) hydrogels. In addition, we also conducted a preliminary in vivo evaluation of cartilage repair in rabbit knee chondral defects treated with subchondral bone microfracture and cell-free PEGDA with and without HA. Under in vitro conditions, the interfacial shear strength between tissue engineered cartilage derived from HBMSCs and osteoarthritic chondrocytes was significantly higher (p < 0.05) when HA nanoparticles were incorporated within the HBMSC culture system. Histological evidence confirmed a distinct spatial transition zone, rich in calcium phosphate deposits. Assessment of explanted rabbit knees by histology demonstrated that cellularity within the repair tissues that had filled the defects were of significantly higher number (p < 0.05) when HA was used. HA nanoparticles play an important role in treating chondral defects when osteoarthritis is a co-morbidity. We speculate that the calcified layer formation at the interface in the osteoarthritic environment in the presence of HA is likely to have attributed to higher interfacial strength found in vitro. From an in vivo standpoint, the presence of HA promoted cellularity in the tissues that subsequently filled the chondral defects. This higher presence of cells can be considered important in the context of accelerating long-term cartilage remodeling. We conclude that HA nanoparticles play an important role in engineered to native cartilage integration and cellular processes.

Bone alterations are associated with ankle osteoarthritis joint pain

The etiology of ankle osteoarthritis (OA) is largely unknown. We analyzed 24 ankle OA of 21 patients diagnosed by plain radiographs using magnetic resonance imaging (MRI). Ankle joint pain disappeared in 22 out of 24 joints by conservative treatment. MRI bone signal changes in and around the ankle joints were observed in 22 of 24 joints. Bone signal changes along the joint line were seen in 10 of 11 joints as a Kellgren-Lawrence (KL) grade of II to IV. Such signal changes were witnessed in only 4 of 13 joints with KL grade 0 or I. In the talocrural joint, bone alterations occurred in both tibia and talus bones through the joint line in cases of KL grade III or IV, while focal bone alterations were present in the talus only in KL grade I or II cases. Sixteen of 24 joints exhibited intraosseous bone signal changes, which tended to correspond to joint pain of any ankle OA stage. Our results suggest that bone alterations around the ankle joint might be one of the etiologies of OA and associated with ankle joint pain.

Outcomes after Total Knee Arthroplasty for post-traumatic arthritis

INTRODUCTION

Total Knee Arthroplasty (TKA) is an important treatment for posttraumatic arthritis (PTA), but evidence on outcomes is sparse. The purpose of this study was to evaluate the impact of PTA versus primary osteoarthritis (OA) on postoperative outcomes after TKA.

METHODS

We queried the entire Medicare database from 2005 to 2012. International Classification of Diseases, 9th revision and Current Procedural Terminology codes were used to identify the procedure, indication, and complications. Patients with minimum two-years follow-up were selected. Odds ratios (ORs), confidence intervals, and p-values (p) were calculated.

RESULTS

For PTA, 3509 patients had TKA. For OA, 257,611 patients with TKA served as controls. The average Charlson Comorbidity Index for both groups was five. PTA patients were younger; only eight out of 29 Elixhauser comorbidities were higher. PTA patients had higher incidence of periprosthetic infection (OR 1.72, p<0.001), cellulitis or seroma (OR 1.19, p<0.001), knee wound complications (OR 1.80, p<0.001), TKA revision (OR 1.23, p=0.01), and arthrotomy/incision and drainage (OR 1.55, p<0.001). Blood transfusion rate was lower in PTA patients. There were no significant differences in bleeding complications, prosthetic dislocation, broken prostheses, periprosthetic fracture, osteolysis and polywear, neurovascular injury, and extensor mechanism rupture.

DISCUSSION AND CONCLUSION

This study represents, to our knowledge, TKA outcomes in the largest cohort of PTA patients to date. Our findings indicate that these patients are at higher risk for many, but not all, postoperative surgical complications despite being as healthy as patients receiving TKA for primary OA.

Differential Interactive Effects of Cartilage Traumatization and Blood Exposure In Vitro and In Vivo

BACKGROUND

Sport injuries of the knee often lead to posttraumatic arthritis. In addition to direct damage of the cartilage, trauma-associated intra-articular bleeding may cause hemarthrosis. Both blood exposure and trauma are known to induce cell death and inflammation and to enhance proteoglycan release in cartilage.

HYPOTHESIS

Blood exposure increases chondrocyte death as well as inflammatory and degenerative processes in traumatized cartilage.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human macroscopically intact osteoarthritic (OA) cartilage explants were impacted by a drop-tower system (0.59 J) and cultivated with or without 10% blood. Interactive effects were studied concerning cell survival, gene expression, and the release of mediators over 24 hours and 96 hours. To evaluate the effects of trauma and hemarthrosis in vivo, a newly established blunt cartilage trauma model in the rabbit was used. Treatment of the knee joints of mature New Zealand White rabbits consisted of the following groups: control (C), arthrotomy (A), arthrotomy with cartilage trauma (AT; 1.0 J), and arthrotomy with cartilage trauma and blood injection (ATH). After 1 and 12 weeks, inflammatory mediators in the synovial fluid and histological changes of the cartilage were determined, and immunohistological staining was performed.

RESULTS

The in vitro studies revealed a significant additional or synergistic effect of blood exposure on trauma-induced chondrocyte death, interleukin (IL)-1β and prostaglandin-E2 (PGE2) release, and matrix metalloproteinase (MMP)/pro-MMP level. Singular arthrotomy in vivo induced a temporary inflammation. Histologically, cartilage trauma caused significant OA changes that were not aggravated by an additional hemarthrosis. Trauma led to a persistent deposition of terminal complement complex (TCC), being enhanced by hemarthrosis. However, trauma-induced formation of osteophytes and arthrotomy-induced elevation of tumor necrosis factor-α release were reduced by hemarthrosis.

CONCLUSION

While blood exposure clearly aggravated trauma-induced OA processes in the in vitro model, a singular blood injection revealed heterogeneous effects in vivo, enhancing TCC deposition but reducing trauma-induced osteophyte formation while the histological score of traumatized cartilage was not further impaired.

CLINICAL RELEVANCE

The results of this study indicate that a singular, limited bleeding event might not exacerbate early trauma-induced cartilage degeneration in joint injuries. An early removal of intra-articular blood may not prevent the final resulting cartilage damage.

A clinically realistic large animal model of intra-articular fracture that progresses to post-traumatic osteoarthritis

OBJECTIVE

Translation of promising treatments for post-traumatic osteoarthritis (PTOA) to patients with intra-articular fracture (IAF) has been limited by the lack of a realistic large animal model. To address this issue we developed a large animal model of IAF in the distal tibia of Yucatan minipigs and documented the natural progression of this injury.

DESIGN

Twenty-two fractures were treated using open reduction and internal fixation with either an anatomic reduction or an intentional 2-mm step-off. Pre-operatively, and 3 days, 1, 2, 4, 8, and 12 weeks post-operatively, animals were sedated for synovial fluid draws and radiographs. Limb loading was monitored at the same time points using a Tekscan Walkway. Animals were sacrificed at 12 weeks and the limbs were harvested for histological evaluation.

RESULTS

All animals achieved bony union by 12 weeks, facilitating nearly complete recovery of the initial 60% decrease in limb loading. TNFα, IL1β, IL6, and IL8 concentrations in the fractured limbs were elevated (P < 0.05) at specific times during the 2 weeks after fracture. Histological cartilage degeneration was more severe in the step-off group (0.0001 < P < 0.27 compared to normal) than in the anatomic reconstruction group (0.27 < P < 0.99 compared to normal).

CONCLUSIONS

This model replicated key features of a human IAF, including surgical stabilization, inflammatory responses, and progression to osteoarthritic cartilage degeneration, thereby providing a potentially useful model for translating promising treatment options to clinical practice.

Management of high-energy tibial pilon fractures

Tibial pilon fractures result from high-energy trauma unlike usual ankle fractures. Their management provides numerous challenges to the orthopaedic surgeon including obtaining anatomic reduction of articular surface and the management of associated soft tissue injuries. This article aims to review major advances and principles that guide our practice today. We also discuss a treatment algorithm based on a staged approach to the fracture: initial spanning external fixation followed by definitive fixation.

Therapeutic opportunities to prevent post-traumatic arthritis: Lessons from the natural history of arthritis after articular fracture

An estimated 12% of patients seeking surgical intervention for symptomatic arthritis have an etiology of post-traumatic arthritis (PTA). The onset of PTA is rapid in the setting of articular fracture (AF). The investigation began with development of a murine model of a closed AF that develops PTA. In the process of characterizing this model a technique was developed for assessing quantitative synovial fluid biomarker concentrations. The work began with observations of the natural history of PTA development in the C57BL/6 strain of mice. A species of mice (MRL/MpJ) was found that is protected from PTA after AF. Further work identified key differences between mouse strains that did and did not develop PTA. This knowledge led to an intervention based on anti-cytokine (interleukin 1 receptor antagonist, (IL-1Ra) delivery in the C57BL/6 strain of mice that successfully prevented PTA following AF. This success in preventing PTA in the murine model has elucidated several important clinical implications: 1) Pro-inflammatory cytokines play an important role in the development of PTA after joint injury, 2) Pharmacologic intervention can lessen the severity of PTA after an AF, and 3) The murine AF model of joint injury provides a novel means of studying mechanisms of PTA development.

Generation and characterization of osteochondral grafts with human nasal chondrocytes

We investigated whether nasal chondrocytes (NC) can be used to generate composite constructs with properties necessary for the repair of osteochondral (OC) lesions, namely maturation, integration and capacity to recover from inflammatory burst. OC grafts were fabricated by combining engineered cartilage tissues (generated by culturing NC or articular chondrocytes - AC - onto Chondro-Gide® matrices) with devitalized spongiosa cylinders (Tutobone®). OC tissues were then exposed to IL-1β for three days and cultured for additional 2 weeks in the absence of IL-1β. Cartilage maturation extent was assessed (immune) histologically, biochemically and by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) while cartilage/bone integration was assessed using a peel-off mechanical test. The use of NC as compared to AC allowed for more efficient cartilage matrix accumulation and superior integration of the cartilage/bone layers. dGEMRIC and biochemical analyzes of the OC constructs showed a reduced glycosaminoglycan (GAG) contents upon IL-1β administration. Cartilaginous matrix contents and integration forces returned to baseline up on withdrawal of IL-1β. By having a cartilage layer well developed and strongly integrated to the subchondral layer, OC tissues generated with NC may successfully engraft in an inflammatory post-surgery joint environment.

Sustained intra-articular delivery of IL-1RA from a thermally-responsive elastin-like polypeptide as a therapy for post-traumatic arthritis

Post-traumatic arthritis (PTA) is a rapidly progressive form of arthritis that develops due to joint injury, including articular fracture. Current treatments are limited to surgical restoration and stabilization of the joint; however, evidence suggests that PTA progression is mediated by the upregulation of pro-inflammatory cytokines, such as interleukin-1 (IL-1) or tumor necrosis factor-α (TNF-α). Although these cytokines provide potential therapeutic targets for PTA, intra-articular injections of anti-cytokine therapies have proven difficult due to rapid clearance from the joint space. In this study, we examined the ability of a cross-linked elastin-like polypeptide (xELP) drug depot to provide sustained intra-articular delivery of IL-1 and TNF-α inhibitors as a beneficial therapy. Mice sustained a closed intra-articular tibial plateau fracture; treatment groups received a single intra-articular injection of drug encapsulated in xELP. Arthritic changes were assessed 4 and 8 weeks after fracture. Inhibition of IL-1 significantly reduced the severity of cartilage degeneration and synovitis. Inhibition of TNF-α alone or with IL-1 led to deleterious effects in bone morphology, articular cartilage degeneration, and synovitis. These findings suggest that IL-1 plays a critical role in the pathogenesis of PTA following articular fracture, and sustained intra-articular cytokine inhibition may provide a therapeutic approach for reducing or preventing joint degeneration following trauma.

Role of Complement on Broken Surfaces After Trauma

Activation of both the complement and coagulation cascade after trauma and subsequent local and systemic inflammatory response represent a major scientific and clinical problem. After severe tissue injury and bone fracture, exposure of innate immunity to damaged cells and molecular debris is considered a main trigger of the posttraumatic danger response. However, the effects of cellular fragments (e.g., histones) on complement activation remain enigmatic. Furthermore, direct effects of "broken" bone and cartilage surfaces on the fluid phase response of complement and its interaction with key cells of connective tissues are still unknown. Here, we summarize data suggesting direct and indirect complement activation by extracellular and cellular danger associated molecular patterns. In addition, key complement components and the corresponding receptors (such as C3aR, C5aR) have been detected on "exposed surfaces" of the damaged regions. On a cellular level, multiple effects of complement activation products on osteoblasts, osteoclasts, chondrocytes and mesenchymal stem cells have been found.In conclusion, the complement system may be activated by trauma-altered surfaces and is crucially involved in connective tissue healing and posttraumatic systemic inflammatory response.

Palmitate has proapoptotic and proinflammatory effects on articular cartilage and synergizes with interleukin-1

OBJECTIVE

Obesity is a major risk factor for the development of osteoarthritis (OA) that is associated with a state of low-grade inflammation and increased circulating levels of adipokines and free fatty acids (FFAs). The aim of this study was to analyze the effects of saturated (palmitate) and monounsaturated (oleate) FFAs on articular chondrocytes, synoviocytes, and cartilage.

METHODS

Human articular chondrocytes and fibroblast-like synoviocytes obtained from young healthy donors and OA chondrocytes from patients undergoing total knee replacement surgery were treated with palmitate or oleate alone or in combination with interleukin-1β (IL-1β). Cell viability, caspase activation, and gene expression of proinflammatory factors, extracellular matrix (ECM) proteins, and proteases were studied. In addition, chondrocyte viability, IL-6 production, and matrix damage were assessed in bovine and human articular cartilage explants cultured with FFAs in the presence or absence of IL-1β.

RESULTS

Palmitate, but not oleate, induced caspase activation and cell death in IL-1β-stimulated normal chondrocytes, and up-regulated the expression of IL-6 and cyclooxygenase 2 in chondrocytes and fibroblast-like synoviocytes through Toll-like receptor 4 (TLR-4) signaling. In cartilage explants, palmitate induced chondrocyte death, IL-6 release, and ECM degradation. Palmitate synergized with IL-1β in stimulating proapoptotic and proinflammatory cellular responses. Pharmacologic inhibition of caspases or TLR-4 signaling reduced palmitate and IL-1β induced cartilage damage.

CONCLUSION

Palmitate acts as a proinflammatory and catabolic factor that, in synergy with IL-1β, induces chondrocyte apoptosis and articular cartilage breakdown. Collectively, our data suggest that elevated levels of saturated FFAs that are often found in patients who are obese may contribute to the pathogenesis of OA.