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OA frequency at long-term follow-up is a concern in patients with cartilage repair
Patients who underwent microfracture and reached the 15-year follow-up had significantly better Tegner activity scores than patients treated with ACI.
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An investigator reported 15-year survival of 57.5% after autologous chondrocyte implantation and 67.5% after microfracture among patients in a multicenter randomized trial who were treated for condylar defects in 1999 or 2000 with either cartilage repair technique.
The patients, who were deemed failures, went on to undergo a variety of treatments, Gunnar Knutsen, MD, of Tromsø, Norway, said at the International Cartilage Repair Society (ICRS) Annual Meeting, here.
“Among the failures, we had six total knee in the [autologous chondrocyte implantation] ACI group and four [high tibial osteotomies] HTOs. Microfracture equals three total knees and four HTOs,” he said, noting the differences between the groups for failures and survival at 15-year follow-up were not statistically significant.
Symptomatic condylar defect
Originally 80 patients — 40 per group — with one symptomatic chronic cartilage defect on the femoral condyle were included in the study. At the time, the patients did not have general osteoarthritis (OA). To track data, the investigators used the Lysholm, ICRS, SF-36 and Tegner scores at baseline and at each follow-up.
In addition, patients were initially evaluated via standing weight-bearing radiographs for the presence of radiographic OA based on Kellgren and Lawrence (KL) grade.
According to the abstract, for the 15-year OA assessment, the investigators used a Synaflexer frame (Synarc Inc.) to standardize the radiographs. They defined failure as any reoperation that was performed because the treated lesion was symptomatic and did not heal.
Failures analyzed
In all, there were 17 failures in the ACI group and 13 failures in the microfracture group.
“We did not find two patients at the last follow-up. Both were microfractures and they were non-failures at five [years], so we tried everything to find them, but it was not possible,” Knutsen said.
Knutsen and colleagues defined a clinical failure as a patient with a Lysholm score of 64 points or lower.
However, even when they included the two lost patients who had microfracture in the failure group, there were still no significant differences between the two groups, Knutsen said.
This was also the case at long-term follow-up for the pain scores and SF-36 physical component scores in both groups — no significant difference.
“However, microfracture patients surviving have a significantly better Tegner score at 15 [years] — 14 to 15 years,” he said.
The abstract showed long-term Tegner scores of 4.8 and 4.0 in the microfracture and ACI groups, respectively.
If the median rather than the mean score Tegner score is used, this difference is not significant. “We believe median is to be preferred for Tegner,” Knutsen told Orthopaedics Today Europe.
OA rates similar in both groups
The investigators took a closer look at the presence of OA in all these patients.
“About half of the patients have some early signs of OA,” Knutsen said.
The investigators reported that 57% of ACI patients and 48% of microfracture patients had early radiographic evidence of OA defined as KL scores of two points or more. However, the difference in OA rates between the groups was not significant. Furthermore, there was no significant difference in OA rates for the cases that were failures and non-failures, Knutsen said.
The limitations of the study were its original inclusion of chronic patients and relatively few patients, as well as the fact four centers participated. According to Knutsen, there was some variability in outcomes by center.
“One center had 60% of the failures for ACI,” he said.
“In our study, we cannot say ACI was favored,” but clinicians should start treatment of these lesions with a minimal procedure, such as debridement, Knutsen said.
“Good quality repair seem to be important and we need improvements, and we need ICRS for moving forward,” he said. – by Susan M. Rapp
- Reference:
- Knutsen G, et al. Paper #8.3.7. Presented at: International Cartilage Repair Society Annual Meeting; May 8-11, 2015; Chicago.
- For more information:
- Gunnar Knutsen, MD, can be reached at Department of Orthopaedic Surgery, University of Tromsø, University Hospital North Norway, 9038 Tromsø, Norway; email: gunnar.knutsen@unn.no.
Disclosure: Knutsen reports no relevant financial disclosures.
Perspective
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Giuseppe Filardo, MD, PhD
No currently available treatment may provide optimal results either in terms of cartilage regeneration or clinical improvement. However, there is an increasing awareness that the quality of the repaired/regenerated tissue plays a key role in determining the final outcome, especially the long-term results. Several treatments are emerging aimed at restoring a hyaline articular surface. At the same time, the literature shows how not all patients may benefit equally from the different cartilage treatment options, with lower results and a higher failure rate in more degenerated joints where the regenerative potential may be not sufficient to offer good results after a regenerative treatment. Thus, results of some studies may be affected by the patient selection. One such study is this long-term autologous chondrocyte implantation vs. microfracture (MFX) study which shows a high percentage of osteoarthritis occurred since the first follow-up, which means possibly a population was targeted after the point of no return in the degenerative progression and, therefore, they were not the best candidates for a regenerative procedure. On the other hand, as documented in the experience of our group and by an increasing number of literature reports, non-degenerative lesions can benefit more from a regenerative approach, which in this patient population may offer longer-lasting results than MFX.
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