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Cartilage repair methods advance now yield up to 90% improvement
Investigators sort out differences in microfracture, ACI and mosaicplasty. None yet proved best.
Orthopedic surgeons are increasingly using three promising methods of knee cartilage repair and regeneration: microfracture, autologous chondrocyte implantation and mosaicplasty (or osteochondral autograft transfer).
Clinicians have found these options attractive because they can achieve significant clinical improvements in pain and activity level in up to 90% of cases.
Yet, experts still regularly point out that no one repair method has been shown to consistently produced hyaline cartilage.
“Healing of cartilage means restoring of function, not necessarily to restore the anatomical function or normal tissue, but to relieve symptoms,” said Lars Peterson, MD, PhD, of the University of Gothenburg, Sweden, at the 6th Symposium of the International Cartilage Repair Society (ICRS). “Regeneration is what we are aiming for, meaning we want to replace the damaged area and have a tissue identical to the original.”
In search of hyaline repair
Courtesy of Chris R. Gooding |
Histological studies of the articular cartilage repair tissues produced by these three techniques yielded important information. While these findings are helping to shape future directions in cartilage repair, they also leave scientists wondering why some treatments strictly produce fibrocartilage while others turn out more hyaline-like cartilage, and why fully hyaline repairs still elude them.
In the absence of any ideal knee cartilage repair techniques, orthopedic surgeons must evaluate these approaches independently, realizing they have clinical tradeoffs. One procedure might require more than one surgery to complete, another may be done arthroscopically or require removing perfectly good cartilage from one area of the knee to create new cartilage in an affected area.
Clinicians also need to ask themselves, case-by-case, whether the technique selected is appropriate and indicated for the defect size, type and location, and whether the repair quality matches the patient’s lifestyle and meets long-term functional goals.
Updated results
At this juncture in the evolution of cartilage repair, there is good news: Some of the best techniques available have consistently produced good functional results. They have been shown to also significantly reduce knee pain or provide effective defect coverage.
Investigators recently reported updated results with the three most popular techniques at the recent ICRS meeting and Orthopedics Today NY 2005 – A comprehensive CME course, presenting outcomes for such indications as femoral condyle (FC), patellofemoral (PF) joint and trochlear defects.
At the ICRS meeting, P.C. Kreuz, MD, of Freiburg, Germany, reported results in 85 patients who had full thickness lesions treated with microfracture from 1999 to 2002 (39.5 years old, mean). The technique produced “good short-term results in the treatment of small cartilage defects,” according to the abstract. However, authors said results started to worsen at 18 months postoperatively, as evidenced by deterioration of ICRS cartilage scores.
J. Richard Steadman, MD, who popularized microfracture, has performed the arthroscopic procedure in more than 2000 patients. It is mainly indicated for chondral defects in the knee. When used for that indication, Steadman reported 75% to 80% of patients achieved significant pain relief and could better perform more activities and sports. The rest showed either no change in their knees or continued joint deterioration.
The hybrid of articular-like and fibrocartilage tissue produced through microfracture is “durable and functions similarly to articular cartilage,” according to information on the Web site for the Steadman-Hawkins Clinic, Vail, Colo., where Steadman practices.
Apples and oranges?
In five-year results of a randomized multicenter trial where 80 patients underwent either microfracture or autologous chondrocyte implantation (ACI) for single FC cartilage lesions, both procedures yielded similar clinical results, according to Gunnar Knutsen, MD, of Tromso, Norway. He presented results at the ICRS meeting.
Investigators found that at two and five years post-treatment, both groups exhibited clinically significant improvements. At two years, based on SF-36 physical component scores, the patients with a microfracture had a significantly greater improvement, but not at five years.
“We can see that the patients are getting less pain, but at one, two and five years there’s no significant difference. And pain is an important factor for these patients,” Knutsen said. He reported nine failures (22%) in each group at five years.
Despite marked clinical improvements in younger and more active patients, researchers found “no correlation between histology and clinical outcome. We believe that we have to report the results at 10 years,” they said.
ACI results
ACI is indicated for symptomatic chondral and osteochondral FC lesions, including osteochondritis dissecans (OCD), in patients 15- to 55-years-old with lesions from 1 to 2 cm2 to about 16 cm2, according to Peterson. Investigators have mostly used ACI for FC lesions and have the longest follow-up thus far for that indication.
Peterson discussed his outcomes with ACI, the two-step cell-based cartilage repair technique developed in the 1980s that he began using nearly two decades ago. The first 23 patients achieved 87% good or excellent results, which improved to 89% by five to 11 years postop.
At the five- to 11-year follow-up, 76% of patients with patellar lesions had good or excellent results following ACI, he said.
Results through 18 years
“We have improved the results slowly up to 81%” for FC lesions with concomitant ACL treatments, Peterson said. Among patients with tibial lesions, 62% had good or excellent results.
For trochlea and tibiofemoral bipolar lesion indications, he reported 80% and 25% good or excellent results, respectively. Deep bony defects may also be effectively treated by ACI. “In OCD [cases], we see a good result in over 90%,” Peterson said.
Although some cartilage repair techniques are better suited for certain size defects, “The size of the defect seems not so important with ACI,” based on current results, Peterson said. “You can address large defects especially if they have containment with a cartilage surrounding.”
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Peterson and colleagues have operated on defects to 18 cm2, as well as some larger ones, with good results.
“It seems the durability of this procedure is better than I expected,” Peterson said of his 10- to 18-year results.
For instance, 50% of ACI-treated patients followed long term reported improved knee function or no change in their knee beyond the five-year follow-up. They represent 71% of Peterson’s patients to date.
Genzyme Biosurgery’s Carticel product, the only ACI product approved in the United States, has been used in more than 10,000 procedures since March 1995. It is indicated for use in the distal femur, including the medial and lateral femoral condyles and the trochlea.
The Genzyme registry of Carticel implantations tracks results using the modified Cincinnati knee rating score. Five-year Carticel data from a multicenter study published in August showed outcomes were similar to ones at three years post-treatment, meaning the repairs have durability, said Genzyme’s Roland P. DeAngelis Jr., director of Carticel marketing.
“I think that as we continue to collect data on these patients, it becomes more and more clear in the orthopedic surgeon’s mind as to which patients are going to be able to benefit the most,” he said. “I think careful selection criteria have definitely evolved over the last 10 years.”
Recent Carticel outcome studies highlighted the crucial role that mechanical alignment, cruciate instability and meniscal status play in relation to the surgical result, and a study by Freddie H. Fu, MD, et al, showed the procedure is well suited for higher-demand patients with large chondral defects.
Laszlo Hangody, MD, at Uzsoki Hospital, Budapest, Hungary, said mosaicplasty “is not the universal solution for every kind of cartilage defect. We know very well that this technique is an actual compromise.”
In a presentation at the ICRS meeting, he addressed some technique-related concerns, like the quality of the resurface tissue produced when using mosaicplasty. “This is only incomplete cartilage, not a true hyaline cartilage,” he said.
The technique, performed arthroscopically or through a mini-arthrotomy, is mainly indicated for FC lesions, Hangody said.
It involves harvesting small cartilage grafts from nonweight-bearing surfaces of the knee being treated and implanting them like pieces of a mosaic into a debrided defect. “Our aim is to create a composite cartilage layer consisting of transplanted hyaline cartilage and a certain amount of fibrocartilage,” Hangody said.
Of the more than 1000 mosaicplasties he has performed in the past 14 years, patients with FC or patellar lesions had 90% good or excellent results, but those with PF defects attained less favorable ones.
Mosaicplasty studies conducted by independent investigators confirmed these findings with success rates from 80% and 90%, Hangody noted.
For more information:
- Kreuz PC, Steinwachs M, Krause SJ, et al. Microfracture to resurface full-thickness chondral defects of the knee: 3-year results of 85 patients. #1-1.
- Knutsen G, Drogset JO, Engebretsen L, et al. Autologous chondrocyte implantation compared with microfracture in the knee (five-year follow-up). #1-3.
- Peterson L. Autologous chondrocyte implantation. #2-A.
- Hangody L. Mosaicplasty. #2-B. All presented at the 6th Symposium of the International Cartilage Repair Society. Jan. 8-11, 2006. San Diego.
- Cole, BJ. Cartilage restoration: Clinical update and treatment algorithm. Presented at Orthopedics Today NY 2005 – A comprehensive CME course. Nov. 19-20, 2005. New York.