Cartilage Repair Capacity within a Single Full-Thickness Chondral Defect in a Porcine Autologous Matrix-Induced Chondrogenesis Model Is Affected by the Location within the Defect

Objective Large articular cartilage defects are a challenge to regenerative surgery. Biomaterial scaffolds might provide valuable support for restoration of articulating surface. The performance of a composite biomaterial scaffold was evaluated in a large porcine cartilage defect. Design Cartilage repair capacity of a biomaterial combining recombinant human type III collagen (rhCo) and poly-(l/d)-lactide (PLA) was tested in a porcine model. A full-thickness chondral defect covering the majority of the weightbearing area was inflicted to the medial femoral condyle of the right knee. Spontaneous cartilage repair and nonoperated healthy animals served as controls. The animals were sacrificed after a 4-month follow-up. The repair tissue was evaluated with the International Cartilage Repair Society (ICRS) macroscopic score, ICRS II histological score, and with micro-computed tomography. Additionally, histopathological evaluation of lymph nodes and synovial samples were done for toxicological analyses. Results The lateral half of the cartilage defect in the operated groups showed better filling than the medial half. The mean overall macroscopic score for the rhCo-PLA, spontaneous, and nonoperated groups were 5.96 ± 0.33, 4.63 ± 0.42, and 10.98 ± 0.35, respectively. The overall histological appearance of the specimens was predominantly hyaline cartilage in 3 of 9 samples of the rhCo-PLA group, 2 of 8 of the spontaneous group, and 9 of 9 of the nonoperated group. Conclusions The use of rhCo-PLA scaffold did not differ from spontaneous healing. The repair was affected by the spatial properties within the defect, as the lateral part of the defect showed better repair than the medial part, probably due to different weightbearing conditions.

Osteochondral Peg Fixation for Chondral Fragment of the Knee in Adolescent Patients: A Report of Two Cases

Introduction. Purely chondral injuries of the knee are relatively rare, and no consensus exists on the appropriate treatment in such cases. We describe two adolescent patients with chondral injury of the knee who were successfully treated by osteochondral peg fixation. Patients, Concerns, and Clinical Findings. In case 1, a 14-year-old boy presented with complaints of right knee pain after landing on his leg while playing basketball. Radiography and computerized tomography revealed no abnormalities. However, magnetic resonance imaging revealed a chondral defect in his lateral femoral condyle and a loose chondral fragment measuring 6.5 cm2. In case 2, a 12-year-old boy presented with complaints of left knee pain after a rotational injury while playing baseball. Similar to case 1, magnetic resonance imaging revealed a chondral defect in his lateral femoral condyle and a loose chondral fragment measuring 3.0 cm2. Primary Diagnosis, Interventions, and Outcomes. The two patients were treated by surgical fixation using osteochondral pegs, which were harvested from the femoral condyle. After a year, postoperative computerized tomography and magnetic resonance imaging showed union of the chondral fragment with the osteochondral pegs and surrounding tissue. In both cases, the Lysholm score was 100 points at the final follow-up more than 2 years after surgery. Conclusion. The findings reported herein suggest that osteochondral peg fixation is a feasible treatment option for chondral injury of the knee, with satisfactory outcomes.

Clinical Results of A Novel Arthroscopic Microfracture Technique For Chondral Lesions of The Lunate

PurposeChondral lesions of the lunate are one of the causes of ulnar-sided pain, but there has been little interest to date in treating them. In this paper, we describe a modification of the subchondral drilling technique in which an 18-gauge (G) needle was used as a sleeve to guide a K-wire to the lunate chondral defect.MethodsEleven patients (nine women, two men) who had undergone a simultaneous arthroscopic wafer procedure and lunate microfracture between 2014 and 2017 were retrospectively reviewed. After completion of the arthroscopic wafer procedure, an 18G needle was placed into the joint via the 6R portal and the needle tip was inserted into the subchondral bone. A 0.8-mm K-wire was then advanced through the needle and the lunate was drilled to a 2–3-mm depth. It is possible to safely drill remaining areas by only changing the direction of the needle. ResultsEight patients met inclusion criteria. There was no significant difference between the preoperative and postoperative wrist range of motion (p>0.05). Grip strength was significantly improved postoperatively (p<0.05). According to the Mayo wrist scoring system, six and one patients had excellent and good results, respectively.ConclusionArthroscopic lunate microfracture is an effective treatment for chondral defects of the lunate in the setting of ulnar impaction syndrome, and using a needle as a sleeve can ease manipulation and increase accuracy. Level of Evidence: IV

Chondral Defects Cause Kissing Lesions in a Porcine Model

Objective To assess the development of kissing lesions 12 months after the generation of full-thickness chondral defects. Design Eight minipigs were randomized into 2 groups: the Φ8.5 mm full-thickness chondral defect group (8.5FT group) and the Φ6.5 mm full-thickness chondral defect group (6.5FT group). The Φ8.5 mm or Φ6.5 mm full-thickness chondral defects were prepared in the medial femoral condyle. Knee magnetic resonance imaging (MRI) was performed before sacrifice. India ink staining was performed to macroscopically assess kissing lesions. Histologic staining (hematoxylin-eosin [HE], safranin O/fast green, toluidine blue staining) and immunohistochemistry (collagen I, collagen II, collagen X, MMP-3) were performed. Microcomputed tomography analysis was completed to assess subchondral bone alterations. Results Obvious kissing lesions were observed on the tibial plateau. Knee MRI demonstrated high cartilage signal intensity in the medial femoral condyle and opposite tibial plateau. HE staining demonstrated cartilage fibrillation and prominent cell death. The depletion of safranin O, toluidine blue staining, and collagen II was observed in the kissing lesion areas. The kissing lesion areas demonstrated increased collagen I, Collagen X, and MMP-3 expression. The 8.5FT group showed a significantly lower mean trabecular number (2.80 1/mm) than the control group (3.26 1/mm). The 6.5FT group showed a significantly increased mean trabecular thickness (0.54 mm) and a decreased mean trabecular number (2.71 1/mm) compared to the control group (0.32 mm; 3.26 1/mm). Conclusions Obvious kissing lesions were observed on the tibial plateau. Knee MRI demonstrated high cartilage signal The presented findings support the development of kissing lesions caused by full-thickness chondral defects.

Small-Diameter Subchondral Drilling Improves DNA and Proteoglycan Content of the Cartilaginous Repair Tissue in a Large Animal Model of a Full-Thickness Chondral Defect

This study quantified changes in the DNA content and extracellular matrix composition of both the cartilaginous repair tissue and the adjacent cartilage in a large animal model of a chondral defect treated by subchondral drilling. Content of DNA, proteoglycans, and Type II and Type I collagen, as well as their different ratios were assessed at 6 months in vivo after treatment of full-thickness cartilage defects in the femoral trochlea of adult sheep with six subchondral drill holes, each of either 1.0 mm or 1.8 mm in diameter by biochemical analyses of the repair tissue and the adjacent cartilage and compared with the original cartilage. Only subchondral drilling which were 1.0 mm in diameter significantly increased both DNA and proteoglycan content of the repair tissue compared to the original cartilage. DNA content correlated with the proteoglycan and Type II collagen content within the repair tissue. Significantly higher amounts of Type I collagen within the repair tissue and significantly increased DNA, proteoglycan, and Type I collagen content in the adjacent cartilage were identified. These translational data support the use of small-diameter bone-cutting devices for marrow stimulation. Signs of early degeneration were present within the cartilaginous repair tissue and the adjacent cartilage.