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Superior results seen in matrix-induced autologous chondrocyte implant compared to microfracture
Treatment failure rates in both groups were lower than investigators expected.
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Investigators of the SUMMIT study recently reported that patients who underwent open matrix-induced autologous chondrocyte treatment showed significant successful pain relief and functional improvement at 2 years.
The prospective, randomized multicenter SUMMIT study was conducted to compare the matrix-induced autologous chondrocyte implant (MACI), which is placed via a mini-open procedure, to microfracture for symptomatic large femoral condyle or trochlear defects at 2-year follow-up.
“We had significantly better results with MACI vs. microfracture,” based on the Knee Injury and Osteoarthritis Outcome Score (KOOS) for pain and function as the primary outcomes, Mats Brittberg, MD, PhD, told Orthopaedics Today Europe. “The most important part is to have the patients experience pain relief and long time durability. All other KOOS subscales were also statistically superior for the MACI implant.”
Sustained pain relief
Brittberg said pain relief and improved function lasted over time and were sustained from the first postoperative follow-up at 36 weeks through the most recent follow-up performed at 104 weeks. The secondary study endpoints addressed the structure of the repairs based on MRI, histology and results of second-look arthroscopy or core samples, or all of these methods, he said.
Investigators used these methods to determine the structural quality of both types of cartilage repair techniques in greater detail.
“We could not discriminate the repair results between the two groups, which does not mean there is not a difference. Maybe in the future we will have better instruments to evaluate this, but they were the secondary outcome scores,” Brittberg said.
Image: Brittberg M
Sizeable phase 3 trial
Brittberg, of the University of Gothenburg and Kungsbacka Hospital, in Kungsbacka, Sweden, presented the findings at the International Society of Arthroscopy, Knee Surgery & Orthopaedic Sports Medicine Congress in Toronto.
He said the trial is the largest cartilage repair study of any kind done to date.
Orthopaedic surgeons in the Netherlands, United Kingdom, Czech Republic, France, Norway and Poland — at 16 sites in all — also participated in the study. They enrolled and treated 144 patients of the 189 patients they initially screened.
Those patients ultimately included in the phase 3 study were aged 18 years to 55 years and had one or more focal knee articular knee cartilage lesion that met the Outerbridge grade III or grade IV classification criteria. Thus, the mean size of the defects the investigators treated was 4 cm2 and ranged from 3 cm2 to 20 cm2.
Patients with Kellgren-Lawrence grade 3 or grade 4 osteoarthritis were excluded.
Technique matters
For patients randomized to undergo microfracture, investigators were instructed to use the trans-arthroscopic microfracture procedure that J. Richard Steadman, MD, originally described so those procedures would all be performed in a similar manner. For the MACI arm, all surgeons were specifically trained in the MACI operative technique.
For consistency, all patients, regardless of treatment group, underwent postoperative rehabilitation with the CPM protocol specified by Steadman, Brittberg said.
The MACI procedure (Sanofi BioSurgery; Cambridge, Mass., USA) used was described as part of the study protocol which investigators were instructed to follow. It involved gluing an appropriately sized membrane seeded with characterized cultured autologous cartilage cells over the debrided defects.
“In this large study that has been well-powered, we could see differences in favor of the MACI implant that have been sustained at 104 weeks, which is important. For sure it will be interesting to see the even longer term results as we follow patients out to 5 years to see how they will do in the long run,” Brittberg said.
Two patients in the microfracture group and no patients in the MACI group failed treatment. At 24 months follow-up, the incidence of adverse events in both groups was similar. – by Susan M. Rapp
- References:
- Brittberg M. Paper #244. Presented at: International Society of Arthroscopy, Knee Surgery & Orthopaedic Sports Medicine Congress; May 12-16, 2013; Toronto.
- www.clinicaltrials.gov/ct2/show/NCT00719676; Accessed June 12, 2013.
- For more information:
- Mats Brittberg, MD, PhD, can be reached at University of Gothenburg, Department of Orthopaedics, Kungsbacka Hospital, S-343 40 Kungsbacka, Sweden; email: mats.brittberg@telia.com.
Disclosure: Brittberg has no relevant financial disclosures for this study.
Perspective
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Giuseppe Filardo, MD
Cartilage surgical treatments are no longer in their infancy, but there is no clear gold standard yet. Despite a tendency of increased quality of cartilage treatment studies over time, most papers are still of limited methodology. In this landscape, the SUMMIT trial represents a milestone, clearly demonstrating with a scientifically sound methodology the clinical superiority of the cell-based approach with respect to microfracture. The study indication criteria are wide, including even patients affected by initial degrees of osteoarthritis. This might have involved the inclusion of patients beyond the point of no return in the joint degeneration processes, thus diminishing the difference documentable between treatments. On the other hand, it demonstrates that a cell-based approach can be successfully applied to a wide patient population that can benefit with a tangible clinical improvement. Many aspects still need to be improved, such as the identification of the most responsive patients and the comparison with other surgical approaches, but this study set the pace for a real step forward in the field of cartilage treatment.
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