Update on Articular Cartilage Restoration:

Rehabilitation and Postoperative Management Practices After Osteochondral Allograft Transplants to the Distal Femur: A Report From the Metrics of Osteochondral Allografts (MOCA) Study Group 2016 Survey

Context:

We present the current spectrum of postoperative management practices for patients receiving distal femur osteochondral allograft (OCA) transplants.

Evidence Acquisition:

The Joint Restoration Foundation database was examined in cooperation with the Metrics of Osteochondral Allografts study group to identify 121 surgeons who had performed at least 1 OCA transplant in the past year; 63% of surgeons responded.

Study Design:

Clinical survey.

Level of Evidence:

Level 3.

Results:

Postoperative weightbearing restrictions ranged from immediate nonweightbearing with full weightbearing by 12 weeks to immediate weightbearing as tolerated. Most surgeons who performed fewer (<10) OCA transplants per year followed the most restrictive protocol, while surgeons who performed more (>20) OCA transplants per year followed the least restrictive protocol. One-third of surgeons with the most restrictive protocol were more likely to change their protocol to be less restrictive over time, while none of those with the least restrictive protocol changed their protocol over time. Fifty-five percent of surgeons permitted return to full activity at 26 weeks, while 27% of surgeons lifted restrictions at 16 weeks.

Conclusion:

Characterization of the spectrum of postoperative management practices after OCA transplantation provides a foundation for future investigations regarding patient outcomes and associated cost to establish best practice guidelines. Fundamentally, surgeons with more experience with this procedure tended to be more aggressive with their postoperative rehabilitation guidelines. Most commonly, rehabilitation provided for some degree of limited weightbearing; however, the spectrum also included immediate full weightbearing practices.

Chitosan-glycerol phosphate/blood implants improve hyaline cartilage repair in ovine microfracture defects

BACKGROUND

Microfracture is a surgical procedure that is used to treat focal articular cartilage defects. Although joint function improves following microfracture, the procedure elicits incomplete repair. As blood clot formation in the microfracture defect is an essential initiating event in microfracture therapy, we hypothesized that the repair would be improved if the microfracture defect were filled with a blood clot that was stabilized by the incorporation of a thrombogenic and adhesive polymer, specifically, chitosan. The objectives of the present study were to evaluate (1) blood clot adhesion in fresh microfracture defects and (2) the quality of the repair, at six months postoperatively, of microfracture defects that had been treated with or without chitosan-glycerol phosphate/blood clot implants, using a sheep model.

METHODS

In eighteen sheep, two 1-cm2 full-thickness chondral defects were created in the distal part of the femur and treated with microfracture; one defect was made in the medial femoral condyle, and the other defect was made in the trochlea. In four sheep, microfracture defects were created bilaterally; the microfracture defects in one knee received no further treatment, and the microfracture defects in the contralateral knee were filled with chitosan-glycerol phosphate/autologous whole blood and the implants were allowed to solidify. Fresh defects in these four sheep were collected at one hour postoperatively to compare the retention of the chitosan-glycerol phosphate/blood clot with that of the normal clot and to define the histologic characteristics of these fresh defects. In the other fourteen sheep, microfracture defects were made in only one knee and either were left untreated (control group; six sheep) or were treated with chitosan-glycerol phosphate/blood implant (treatment group; eight sheep), and the quality of repair was assessed histologically, histomorphometrically, and biochemically at six months postoperatively.

RESULTS

In the defects that were examined one hour postoperatively, chitosan-glycerol phosphate/blood clots showed increased adhesion to the walls of the defects as compared with the blood clots in the untreated microfracture defects. After histological processing, all blood clots in the control microfracture defects had been lost, whereas chitosanglycerol phosphate/blood clot adhered to and was partly retained on the surfaces of the defect. At six months, defects that had been treated with chitosan-glycerol phosphate/blood were filled with significantly more hyaline repair tissue (p < 0.05) compared with control defects. Repair tissue from medial femoral condyle defects that had been treated with chitosan-glycerol phosphate/blood contained more cells and more collagen compared with control defects and showed complete restoration of glycosaminoglycan levels.

CONCLUSIONS

Solidification of a chitosan-glycerol phosphate/blood implant in microfracture defects improved cartilage repair compared with microfracture alone by increasing the amount of tissue and improving its biochemical composition and cellular organization.