Osteochondral necrosis of the femoral condyles in Thoroughbred foals: eight cases (2008–2018)

OBJECTIVE To describe clinical, imaging, gross, and histopathological abnormalities associated with osteochondral necrosis of the femoral condyles in foals and identify features suggestive of a common pathogenesis. ANIMALS 8 Thoroughbred foals euthanized with a presumptive diagnosis of necrosis of the femoral condyles. PROCEDURES Postmortem CT was performed on all distal femoral epiphyseal samples. The articular epiphyseal cartilage complex (AECC) of affected distal femurs was examined grossly and histologically, focusing on lesions of interest identified on CT images. RESULTS 7 foals were between 9 and 23 days old at the time of euthanasia; 1 foal was 85 days old. Concurrent illness (neonatal maladjustment syndrome, neonatal isoerythrolysis, or infection such as enteritis and omphalitis) was diagnosed in 7 foals. The characteristic antemortem radiographic and postmortem CT finding was a crescent-shaped osteochondral flap displaced from the affected medial femoral condyle. Synovial fluid cytology from affected joints was either within normal limits or consistent with mild inflammation. Histologically, all lesions were characterized by osteochondral necrosis and detachment of the AECC. In 6 foals, polymorphonuclear cells were found within growth cartilage canals, representing septic cartilage canals. CLINICAL RELEVANCE Osteochondral necrosis was interpreted to be secondary to bacterial colonization of the distal femoral AECC, evidenced by septic cartilage canals identified in 6 of 8 foals. This uncommon condition was previously thought to arise from an ischemic event, but the disease process was not well understood. An improved understanding of the pathogenesis of osteochondral necrosis is the first step in formulating more successful preventative and treatment strategies.

Outcomes Associated With Osteochondral Allograft Transplantation in Dogs

The purpose of this study was to retrospectively characterize outcomes and complications associated with osteochondral allograft transplantation for treating chondral and osteochondral lesions in a group of client-owned dogs with naturally-occurring disease. Records were reviewed for information on signalment, treated joint, underlying pathology (e.g., osteochondritis dissecans; OCD), and type, size, and number of grafts used. Complications were classified as “trivial” if no treatment was provided, “non-surgical” if non-surgical treatment were needed, “minor surgical” if a minor surgical procedure such as pin removal were needed but the graft survived and function was acceptable, or “major” if the graft failed and revision surgery were needed. Outcomes were classified as unacceptable, acceptable, or full function. Thirty-five joints in 33 dogs were treated including nine stifles with lateral femoral condyle (LFC) OCD and 10 stifles with medial femoral condyle (MFC) OCD treated with osteochondral cylinders or “plugs.” There were 16 “complex” procedures of the shoulder, elbow, hip, stifle, and tarsus using custom-cut grafts. In total there were eight trivial complications, one non-surgical complication, two minor surgical complications, and five major complications for a total of 16/35 cases with complications. Accordingly, there were five cases with unacceptable outcomes, all of whom had major complications while the other 30 cases had successful outcomes. Of the 30 cases with successful outcomes, 15 had full function and 15 had acceptable function. Based on these subjective outcome assessments, it appears osteochondral allograft transplantation is a viable treatment option in dogs with focal or complex cartilage defects. However, no conclusions can be made regarding the inferiority or superiority of allograft transplantation in comparison to other treatment options based upon these data.

Safe femoral condyle range for the reverse Rigidfix femoral fixation device in anterior cruciate ligament reconstruction

Background: To determine the characteristics of cross-pin protrusion in patients treated with the reverse Rigidfix femoral fixation device for femoral tunnel preparation through the anteromedial portal in ACLR, analyse the reasons for this outcome, and identify safety hazards of this surgical technique for improvement. Methods: A retrospective analysis of patients who underwent ACLR using this technology at our hospital in 2018 was conducted. Patients with and without cross-pin protrusion were included in the case and control groups, respectively. The sex, age and imaging characteristics of the patients with cross-pin protrusion were identified, and the reasons for cross-pin protrusion were analysed. Results: There were 64 and 212 patients in the case and control groups, respectively. The proportion of cross-pin protrusion cases was 23.19% (64/276). There was a significant difference in the ratio of males to females (P <0.001, χ2=185.184), the mediolateral femoral condyle diameter (case group, 70.59 ±2.51 mm; control group, 82.65±4.16 mm; P <0.001, t=28.424), and the anteroposterior diameter of the lateral femoral condyle (case group, 58.34±2.89 mm; control group, 66.38±3.53 mm; P <0.001, t=16.615). The cross-pins did not penetrate the lateral femoral condyle cortex in patients with a mediolateral femoral condyle diameter ≥76 mm, but the cross-pins definitely penetrated the cortex when the diameter was ≤70 mm. The cross-pins did not penetrate when the anteroposterior lateral femoral condyle diameter was ≥66 mm, but the cross-pins definitely penetrated it when the diameter was ≤59 mm. Conclusion: The patients with cross-pin protrusion after reverse Rigidfix femoral fixation treatment to prepare the femoral tunnel through the anteromedial portal in ACLR were mainly females with small femoral condyles. For patients with a mediolateral femoral condyle diameter ≥76 mm and an anteroposterior lateral femoral condyle diameter ≥ 66 mm, there is no risk of cross-pin protrusion, so this technique can be used with confidence.

Free Medial Femoral Condyle Flap for Reconstruction of Scaphoid Nonunion: A Systematic Review

Background The free medial femoral condyle (MFC) bone flap is an attractive option for reconstruction of scaphoid nonunion utilizing vascularized bone to augment bony healing, especially in cases of failed prior treatment or osteonecrosis. This review aims to determine the role and reliability of the free MFC flap for treatment of scaphoid nonunion. Methods A search of electronic databases was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles examining free MFC bone flaps for treatment of scaphoid nonunion were included for analysis. Outcomes of interest included flap failure, postoperative union rate, time to union, carpal indices, functional outcomes, and complications. Results Twelve articles met the inclusion criteria. A total of 262 patients underwent free MFC flaps for treatment of scaphoid nonunion. The most common site of nonunion was the proximal pole of the scaphoid with 47% of patients receiving prior attempts at operative management. Overall bony union rate was 93.4% with a mean time to union of 15.6 weeks. There were no flap failures reported. Improvements in carpal indices including scapholunate (p < 0.0004), radiolunate (p < 0.004), lateral interscaphoid angles (p < 0.035), and revised carpal ratio height (p < 0.024) were seen postoperatively. Visual analog scale improved postoperatively from 6.5 to 2.3 (p < 0.015). Postoperative complications were observed in 69 cases (26.3%), with 27 patients (10.3%) requiring further operative intervention. However, no major donor or recipient site morbidity was appreciated. Conclusion MFC flaps provide a highly versatile and reliable option for reconstruction of scaphoid nonunion with excellent bony union rates and acceptable complication rates. The present literature suggests that MFC reconstruction of scaphoid nonunion restores radiocarpal anatomy and improves wrist function without causing significant donor or recipient site morbidity.

Hydrogels with tunable modulus regulate chondrocyte microaggregates growth for cartilage repair

Chondrocyte spheroids in 3D hydrogel are more beneficial to improve their survival and maintain chondrogenic phenotype comparing to dissociated chondrocytes. However, in-situ inducing cell into spheroids rather than encapsulating spheroids in a hydrogel remains a tremendous challenge because of the limitations of biochemical and viscoelastic controllability for hydrogel. Herein, a hydrogel consisting of photo-crosslinkable chitosan methacrylate (CHMA) and semi-interpenetrating polyvinyl alcohol (PVA) is developed as a cell-responsive matrix with controllable viscoelastic properties. The proposed CHMA-PVA precursor preferentially exhibits a weak gel-like state with a storage modulus of 16.9 Pa, loss modulus of 13.0 Pa and yielding stain of 1%, which could allow chondrocyte to vigorously move and assemble but hinder their precipitation before crosslinking. The chondrocytes could form microaggregates within 8 h in vitro and keep high viability. Moreover, subcutaneous implantation experiments demonstrate that the CHMA/PVA hydrogels are biocompatible and degrade within five weeks in vivo. The cell-free hydrogels are further placed in cylindrical cartilage defects in the rabbit femoral condyle and examined 8 weeks postoperatively. Gross, histological and immunohistochemical analyses reveal a significant acceleration for the cartilage regeneration. These findings suggest that this novel cell adhesion-responsive and histo-compatible hydrogel is promising for cartilage regeneration.

Histologically Confirmed Recellularization is a Key Factor that Affects Meniscal Healing in Immature and Mature Meniscal Tears

Healing outcomes of meniscal repair are better in younger than in older. However, exact mechanisms underlying superior healing potential in younger remain unclear from a histological perspective. This study included 24 immature rabbits and 24 mature rabbits. Tears were created in the anterior horn of medial meniscus of right knee in each rabbit. Animals were sacrificed at 1, 3, 6, and 12 weeks postoperatively. We performed macroscopic and histological evaluations of post-meniscal repair specimens. Cells were counted within a region of interest to confirm cellularization at tear site in immature menisci. The width of cell death zone was measured to determine the region of cell death in mature menisci. Apoptosis was evaluated by TUNEL assay. Vascularization was assessed by CD31 immunofluorescence. The glycosaminoglycans and the types 1 and 2 collagen content was evaluated by calculating average optical density of corresponding histological specimens. Cartilage degeneration was also evaluated. Healing outcomes following untreated meniscal tears were superior in immature group. Recellularization with meniscus-like cell morphology was observed at tear edge in immature menisci. Superior recellularization was observed at meniscal sites close to joint capsule than at sites distant from the capsule. Recellularization did not occur at tear site in mature group; however, we observed gradual enlargement of cell death zone. Apoptosis was presented at 1, 3, 6, 12 weeks in immature and mature menisci after untreated meniscal tears. Vascularization was investigated along the tear edges in immature menisci. Glycosaminoglycans and type 2 collagen deposition were negatively affected in immature menisci. We observed glycosaminoglycan degradation in mature menisci and cartilage degeneration, specifically in immature cartilage of the femoral condyle. In conclusion, compared with mature rabbits, immature rabbits showed more robust healing response after untreated meniscal tears. Vascularization contributed to the recellularization after meniscal tears in immature menisci. Meniscal injury fundamentally alters extracellular matrix deposition.

Treating Full Depth Cartilage Defects with Intraosseous Infiltration of Plasma Rich in Growth Factors: An Experimental Study in Rabbits

Objective Intraarticular (IA) administration of platelet-rich plasma (PRP) has been proposed as a new strategy to halt osteoarthritis (OA) progression. In patients with severe OA, its potential is limited because it is unable to reach the subchondral bone, so a new strategy is needed, and intraosseous (IO) infiltration has been suggested. The purpose is to assess the impact of IA together with IO infiltration of plasma rich in growth factors (PRGF) in serum hyaluronic acid (HA) and type II collagen cleavage neoepitope (C2C) levels. Design A total of 32 rabbits were included in the study and randomly divided into 2 groups: control and treatment. A 4-mm chondral defect was created in the medial femoral condyle and IA followed by IO infiltration were performed. Serum C2C and HA levels were measured using enzyme-linked immunosorbent assay (ELISA) tests before infiltration and 28, 56, and 84 days post-infiltration. Results Significant lower C2C serum levels were obtained in treatment group (IA + IO infiltration of PRGF) at 84 days post-infiltration than in control group (IA infiltration of PRGF + IO infiltration of saline solution), while no significant differences between groups were reported at any other study times. Regarding HA, at 56 days post-infiltration, greater significant levels were seen in the treatment group. However, at 84 days post-infiltration, no significant differences were obtained, although lower levels were reported in the treatment group. Conclusions Despite inconclusive, the results suggest that the combination of IA and IO infiltration with PRGF may enhance cartilage and subchondral bone regeneration, but further studies are needed.