Juvenile Osteochondritis dissecans (JOCD) in humans and subchondral cystic lesions (SCL) in horses (also termed radiolucencies) share similarities: they develop in skeletally immature individuals at the same location in the medial femoral condyle (MFC) and their etiology is only partially understood but trauma is suspected to be involved. JOCD is relatively uncommon in people whereas SCLs arise in 6% of young horses leading to lameness. Ischemic chondronecrosis is speculated to have a role in both osteochondrosis and SCL pathogenesis. We hypothesize that MFC radiolucencies develop very early in life following a focal internal trauma to the osteochondral junction. Our aims were to characterize early MFC radioluciencies in foals from 0 to 2 years old. Distal femurs (n=182) from Thoroughbred horses (n=91, 0–2 years old), presented for post-mortem examination for reasons unrelated to this study, were collected. Radiographs and clinical tomodensitometry were performed to identify lesions defined as a focal delay of ossification. Micro-tomodensitometry (m-CT) and histology was then performed on the MFCs (CT lesions and age-matched subset of controls). Images were constructed in 3D. The thawed condyles, following fixation, were sectioned within the region of interest, determined by CT lesion sites. Hematoxylin eosin phloxin and safran (HEPS) and Martius-Scarlet-Blue (MSB) stains were performed. Histological parameters assessed included presence of chondronecrosis, fibrin, fibroplasia and osteochondral fracture. An additional subset of CT control (lesion-free) MFCs (less 6 months old) were studied to identify early chondronecrosis lesions distant from the osteochondral junction. One MFC in clinical CT triages controls had a small lesion on m-CT and was placed in the lesion group. All m-CT and histologic lesions (n=23) had a focal delay of ossification located in the same site, a weight bearing area on craniomedial condyle. The youngest specimen with lesions was less than 2 months old. On m-CT 3D image analysis, the lesions seemed to progressively move in a craniolateral to caudomedial direction with advancing age and development. Seventy-four percent (n=17/23) of the lesions had bone-cartilage separation (considered to be osteochondral fractures) confirmed by the identification of fibrin/clot on MSB stains, representing an acute focal bleed. Fibroplasia, indicating chronicity, was also identified (74%, n=17/23). In four cases, the chondrocytes in the adjacent cartilage were healthy and no chondronecrosis was identified in any sections in the lesions. Nineteen cases had chondronecrosis and always on the surface adjacent to the bone, at the osteochondral junction. None of the subset of control specimens, less than 6 months old (n=44), had chondronecrosis within the growth cartilage. Early subchondral cystic lesions of the medial femoral condyle may arise secondary to focal internal trauma at the osteochondral junction. The presence of fibrin/clot is compatible with a recent focal bleed in the lesion. Medial femorotibial joint internal forces related to geometry could be the cause of repetitive trauma and lesion progression. In the juvenile horse, and potentially humans, the early diagnosis of MFC lesions and rest during the susceptible period may reduce progression and promote healing by prevention of repetitive trauma, but requires further study

We studied twelve parameters (physical appearance, mucin clot, fibrin clot, white cell count, differential count, red blood cell count, gram stain for bacteria, crystal microscopy, aerobic bacterial culture, anaerobic bacterial culture and ratio between synovial sugar and blood sugar) in over 300 samples of synovial fluid from patients with a variety of suspected pathologies (e.g. infection, inflammatory disease, infection adjacent to a joint, aseptic loosening of a prosthesis). The diagnosis of infection was further established using clinical signs, radiological features, full blood count, C-reactive protein and iron profile. Many of the patients came to surgery. This of course created further opportunity to establish or rule out the diagnosis of infection with greater certainty. Nine of the features of synovial fluid were analysed statistically, including turbidity, diminished viscosity, mucin clot, fibrin clot, total white cell count, polymorphs greater than 60%, bacteria observed on direct microscopy, bacteria yielded by culture and concentration of synovial sugar less than 40% of the simultaneous blood sugar. The positive or negative features of infection were determined to be true or false in the light of the cumulative overall features of infection. The data so obtained was analysed to establish sensitivity, specificity, positive predictive value, negative predictive value and accuracy. The mass of data so obtained cannot be meaningfully expressed in such a brief abstract. Important examples are when culturing synovial fluid there were 44% false negatives or no growth and 56% true positives. Looking at the ratio between synovial sugar and blood sugar we found that taking 40% as the critical value, this was 62% sensitive, the specificity was 89%, the accuracy was 73%, the positive predictive value was 89%, the negative predictive value was 62.4%. However we went further and separated those who were definitely infected or probably infected i.e. Groups 4 & 5 from those who were probably or definitely NOT infected according to the sum of clinical laboratory and radiological parameters. When thus separated the predictive value of a positive result was 100% in Group 4 & 5 and 0% in Group 1 & 2. The predictive value of a negative result in Group 1 & 2 was 98.7% accurate and 22.4% in Group 4 & 5

Background. Processing of allografts, which are used to fill bone defects in orthopaedic surgery, includes chemical cleaning as well as gamma irradiation to reduce the risk of infection. Viable bone cells are destroyed and denaturing proteins present in the graft the osteoconductive and osteoinductive characteristics of allografts are altered. The aim of the study was to investigate the mechanical differences of chemical cleaned allografts by adding blood, clotted blood, platelet concentrate and platelet gel using a uniaxial compression test. Methods. The allografts were chemically cleaned, dried and standardized according to their grain size distribution. In group BL 4 ml blood, in CB 4 ml blood and 480 μl of 1 mol calcium chloride to achieve clotting, in PC 4 ml of concentrated platelet gel, in PG 4 ml of concentrated platelets and 666 μl of 1 mol calcium chloride were added. Uniaxial compression test was carried out for the four groups before and after compating the allografts. Results. No statistically significant decrease of the initial density was observed after compaction for BL and PC. In CB a statistical significant decrease of the initial density by 10% was observed, while PG decreased its initial density after compaction by 13%. Considering the density at the yield limit before and after compaction BL showed a statistically significant decrease of 13% and PG of 14%. In CB and PC no statistically significant decrease of the density at the yield limit could be observed. All groups showed a statistical significant difference when comparing the yield limit before and after compaction. BL and PC showed a ∼35% higher yield limit after compaction, while in the groups with the activation liquid CB and PG the yield limit increased by 15% for CB and 20% for PG. No statistically significant difference between groups was found for the density at the yield limit before compaction (p=0.157), for the initial density (p=0.523), the density at the yield limit (p=0.681) and the yield limit itself (p=0.423) after compaction. A statistically significant difference between the groups under investigation was found for the initial density before compaction (p=0.041) and for the yield limit before compaction (p=0.041). BL had a statistically significant lower initial density than PG (p=0.048). All other pairwise comparisons between groups did not reach statistically significance for the initial density before compaction. Conclusion. Adding blood, PRP or PC in allografts has shown in different studies to enhance bone ingrowth. The authors recommend to chemical clean allografts for large defects, optimize their grain size distribution and add platelet concentrate or platelet rich plasma for enhancing as well primary stability as well bone ingrowth. The recommended processing procedure has to be tested in an in-vivo study