FOR Abstract Selected for Presentation at 2018 AAOS Annual Meeting

The American Academy of Orthopaedic Surgeons Central Program Committee has selected our abstract application titled Treatment of Osteochondral Defects of the Knee with Pyrocarbon Implants for presentation at the 2018 AAOS Annual Meeting in New Orleans. The paper (No. 904) will be presented by Samantha L. Salkeld during the Sports Medicine IX Session on Friday, March 9, 2018, from 4:00 – 6:00 pm.

Treatment of Osteochondral Defects of the Knee with Pyrocarbon Implants
Samantha L. Salkeld, MSE, Laura P. Patron, MS , Stephen D. Cook, PhD, Deryk G. Jones, MD, Liam Nolan, Michael Harrison


Patients with focal articular cartilage defects, too young for knee replacement or poor candidates for regenerative procedures (age, BMI or rehabilitation requirements), are left with few treatment options. This study evaluated a pyrolytic carbon (pyrocarbon) implant in a large animal chondral defect model and compared the clinical (pain, gait analysis and lameness), radiologic, gross, and histologic outcomes to control (chondroplasty) defects on the adjacent femoral and opposing meniscus and tibial cartilage.


Twenty-five Suffolk sheep (110kg) were utilized. A 10mm diameter focal chondral defect was created on the medial femoral condyle and treated with either a chondroplasty control (10 animals) or a 10 mm pyrolytic carbon implant (PIR) with a 5mm diameter stem (14 animals). One animal served as a sham operated control. The pyrolytic carbon implant consists of a stem that sits below subchondral bone and a cap that is congruent with the articular surface. Pyrolytic carbon is biocompatible, impervious to wear and provides a low friction surface in articulation with cartilage. The animals were evaluated clinically for pain and lameness, with gait analysis, radiography, and grading of the gross and histopathologic appearance of the cartilage surrounding the implant or chondroplasty site as well as the opposing tibia meniscus and cartilage. Animals were sacrificed at 3 (5 animals), 6 (8 animals) and 12 (11 animals) months postoperative. One animal was terminated early (chondroplasty) at 5 weeks postoperative.


Pain and lameness assessments demonstrated an expected return to normal behavior with time. Gait analysis demonstrated that the operative limb treated with the pyrolytic carbon implants had greater early loading compared to chondroplasty. Radiographically, PIR implants were stable with bone apposition and no change in position over time. The chondroplasty sites exhibited degeneration of the joint space over time. Grossly, PIR implants were well fixed within the condyle with the articular surface border continuous with surrounding cartilage with no evidence of wear or fracture. The PIR implant mean scores for the medial femoral cartilage, meniscus and tibia cartilage reflected minimal tissue changes that occurred after the implant surgery and were similar to chondroplasty. Some changes were observed in the sham operated knee grossly and histologically.

Discussion and Conclusion

The results of the present study are consistent with previous studies that reported less damage to opposing cartilage due to the presence of PIR implants compared to identical Co-Cr alloy implants. Treatment of chondral defects with a pyrolytic carbon resurfacing implant in a large animal model successfully demonstrated a return to normal joint function, acceptable fixation, and safe clinical outcomes compared to chondroplasty control.