"The clinical outcome seems to be comparable to autologous chondrocyte implantation. Still, simpler surgery and lower morbidity can be considered advantages of this technique," said Stefan E. Domayer, MD, of the Medical University of Vienna, Austria.
Dr. Domayer and colleagues reported results at 5 years after MACI with Hyalograft C® (Fidia Advanced Polymers) in 53 patients with knee defects. Hyalograft C is a bioscaffold based on hyaluronan. "The primary indication for Hyalograft concerned young patients with stable ligaments, regular knee alignment, and singular defects with healthy adjacent cartilage. During the first 2 years, implantation was also performed in eight salvage cases," Dr. Domayer said.
The clinical outcome seems to be comparable to autologous chondrocyte implantation. Still, simpler surgery and lower morbidity can be considered advantages of this technique."—Stefan E. Domayer, MD.
Cells for culture were harvested during first-look arthroscopy, then expanded and seeded onto the biopolymer scaffold. Implantation was performed using arthroscopy and miniarthrotomy. MRI was performed using an isotrope fat-suppressed 3D GRE sequence on a 3T MRI unit. Dr. Domayer reported that there was significant improvement in all outcome variables, and that 5-year MRIs available for nine patients showed repair tissue in situ in all of them. "The filling grade was complete in five patients; four had a filling grade over 50%. Integration with surrounding cartilage was complete in all cases. Repair tissue surface was intact in six patients; minor fibrillations were found in three cases. Repair tissue was homogenous in six cases. We found minor bone marrow edema in three patients. Joint effusion was absent in all cases." Seven of eight salvage patients required total knee replacements due to persistent pain; graft failure occurred in four of 45 patients.The researchers concluded that the grafts worked best for "young patients with singular defects and intact adjacent cartilage, ligamentous stability, and regular knee alignment" but are not suited for the treatment of salvage cases.
In a related study, Craig Willers, MD, and colleagues from the University of Western Australia in Perth, reported both a prospective study of MACI in 31 consecutive implantations in 28 patients at least 2 years post-MACI, and a retrospective study of 202 patients who were at least 1 year post-MACI.2 Patients in the prospective study reported improvements in functional ability and had improvements in MRI scores. In the retrospective study, "85% of patients rated their pain relief following MACI as good/excellent, 94% of patients stated they had the ability to participate in sport following MACI, 64% of patients reported no swelling after MACI, 8% of patients reported no occurrence of catching/locking, and 82% of patients rated the overall satisfaction of their MACI outcome as good or excellent," Dr. Willers said. Patients in both cohorts were relatively young: mean age 36.5 years and 36.9 years, respectively.
Judging the quality of the repair tissue is becoming more important; Gotz H. Welsch, MD, from the Medical University of Vienna tested quantitative magnetic resonance T2 mapping as a way of monitoring cartilage repair in patients treated with either microfracture or MACI.3 Dr. Welsch reported that T2 mapping is feasible as a means of differentiating hyaline cartilage from fibrocartilage.
"Quantitative T2 in healthy control cartilage showed a highly significant trend in increasing T2 values from deep to middle to superficial zone (P <.001). Repair tissue after microfracture showed no significant trend between different depths (P = .847) in contrast to repair tissue after [MACI], where a slightly significant increase from deep to superficial zone (P = .045) could be observed," Dr. Welsch said.
References
1. Domayer SE, Nehrer S, Dorotka R, et al. Matrix associated autologous chondrocyte implantation with Hyalograft C in the knee: results at five years. Presented at: OARSI 2007 World Congress on Osteoarthritis; December 6-9, 2007; Fort Lauderdale, Fla. Abstract 238.
2. Willers C, Robertson B, Wood D, et al. Clinical evaluation of matrix-induced autologous chondrocyte implantation: functional and structural restoration, and patient satisfaction. Presented at: OARSI 2007 World Congress on Osteoarthritis; December 6-9, 2007; Fort Lauderdale, Fla. Abstract 258.
3. Welsch GH, Mamisch TC, Domayer S, et al. In vivo differentiation of normal hyaline cartilage and reparative tissue in patients after different cartilage repair procedures—cartilage T2 assessment at 3 tesla. Presented at: OARSI 2007 World Congress on Osteoarthritis; December 6-9, 2007; Fort Lauderdale, Fla. Abstract 29.
2. Willers C, Robertson B, Wood D, et al. Clinical evaluation of matrix-induced autologous chondrocyte implantation: functional and structural restoration, and patient satisfaction. Presented at: OARSI 2007 World Congress on Osteoarthritis; December 6-9, 2007; Fort Lauderdale, Fla. Abstract 258.
3. Welsch GH, Mamisch TC, Domayer S, et al. In vivo differentiation of normal hyaline cartilage and reparative tissue in patients after different cartilage repair procedures—cartilage T2 assessment at 3 tesla. Presented at: OARSI 2007 World Congress on Osteoarthritis; December 6-9, 2007; Fort Lauderdale, Fla. Abstract 29.
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