Differences in joint morphology between the knee and ankle affect the repair of osteochondral defects in a rabbit model

Microdrilling Resulted in Less Subchondral Bone Destruction Than a Traditional Microfracture Awl for Articular Cartilage Defect Bone Marrow Stimulation

Purpose

The purpose of this study was to compare bone marrow stimulation using micro-computed tomography (micro-CT) analysis of an abrasion arthroplasty technique, drilling k-wire technique, traditional microfacture awl, or a microdrill instrument for subchondral bone defects.

Methods

Eleven cadaveric distal femoral specimens were obtained and divided into 3 common areas of osteochondral defect: trochlea and weightbearing portions of the medial and lateral femoral condyles. Each area of interest was then denuded of cartilage using a PoweRasp and divided into quadrants. Each quadrant was assigned either a 1.6 mm Kirschner wire (k-wire), 1.25 mm microfracture awl, 1.5 mm fluted microdrill, PowerPick, or a curette (abrasion arthroplasty) to create 4 channels into the subchondral bone sing the same instrument. Subchondral bone and adjacent tissue areas were then evaluated using micro-CT to analyze adjacent bone destruction and extension into the bone marrow.

Results

Overall, there was a significantly decreased area of bone destruction or compression using the microdrill (0.030 mm) as compared to the microfracture awl (0.072 mm) and k-wire (0.062 mm) (P < .05). Within the trochlea and the medial femoral condyle, there was significantly decreased bony compression with the microdrill as compared to the awl and k-wire (P < .05); however, when stratified, this was not significant among the lateral femoral condylar samples (P = .08).

Conclusion

Bone marrow stimulation causes bony compression that may negatively impact subchondral bone and trabecular alignment. It is important to understand which tools used for bone marrow stimulation cause the least amount of damage to the subchondral bone.

Clinical Relevance

This study demonstrates the decreased subchondral bony defects seen with the microdrill versus the traditional microfracture awl indicating that when performing bone marrow stimulation, the microdrill may be a less harmful tool to the subchondral bone.

3D printing of Mo-containing scaffolds with activated anabolic responses and bi-lineage bioactivities

When osteochondral tissues suffer from focal or degenerative lesions caused by trauma or disorders, it is a tough challenge to regenerate them because of the limited self-healing capacity of articular cartilage. In this study, a series of Mo-doped bioactive glass ceramic (Mo-BGC) scaffolds were prepared and then systematically characterized. The released MoO42- ions from 7.5Mo-BGC scaffolds played a vital role in regenerating articular cartilage and subchondral bone synchronously. Methods: The Mo-BGC scaffolds were fabricated through employing both a sol-gel method and 3D printing technology. SEM, EDS, HRTEM, XRD, ICPAES and mechanical strength tests were respectively applied to analyze the physicochemical properties of Mo-BGC scaffolds. The proliferation and differentiation of rabbit chondrocytes (RCs) and human bone mesenchymal stem cells (HBMSCs) cultured with dilute solutions of 7.5Mo-BGC powder extract were investigated in vitro. The co-culture model was established to explore the possible mechanism of stimulatory effects of MoO42- ions on the RCs and HBMSCs. The efficacy of regenerating articular cartilage and subchondral bone using 7.5Mo-BGC scaffolds was evaluated in vivo. Results: The incorporation of Mo into BGC scaffolds effectively enhanced the compressive strength of scaffolds owing to the improved surface densification. The MoO42- ions released from the 7.5Mo-BGC powders remarkably promoted the proliferation and differentiation of both RCs and HBMSCs. The MoO42- ions in the co-culture system significantly stimulated the chondrogenic differentiation of RCs and meanwhile induced the chondrogenesis of HBMSCs. The chondrogenesis stimulated by MoO42- ions happened through two pathways: 1) MoO42- ions elicited anabolic responses through activating the HIF-1α signaling pathway; 2) MoO42- ions inhibited catabolic responses and protected cartilage matrix from degradation. The in vivo study showed that 7.5Mo-BGC scaffolds were able to significantly promote cartilage/bone regeneration when implanted into rabbit osteochondral defects for 8 and 12 weeks, displaying bi-lineage bioactivities. Conclusion: The 3D-printed Mo-BGC scaffolds with bi-lineage bioactivities and activated anabolic responses could offer an effective strategy for cartilage/bone interface regeneration.