Researchers seek the optimal resurfacing technique for early cartilage damage

Base repair strategy on chondral defect size, bone defect depth and location, and knee alignment.

With the number of surgical techniques and options available, surgeons may benefit from guidelines on how to handle their patients with early cartilage damage.

Allan E. Gross, MD, of the University of Toronto, advised orthopedic surgeons to select a cartilage repair strategy based on the size and diameter of the chondral defect, the depth of the bone defect, the defect location and knee alignment.

Allan E. Gross

“Autologous chondrocyte transplantation … is extremely expensive, but very good for pure cartilage defects. Mosaicplasty … has a high donor site morbidity, but can be done with one operation, and is also better for small defects,” Gross said at the 7th Annual Current Concepts in Joint Replacement Spring 2006 Meeting.

For patients with a chondral or osteochondral defect <3 cm in diameter and <1 cm in depth, Gross recommends surface treatments, including microfracture, autologous chondrocyte transplantation or periosteal grafting. He also performs mosaicplasty on chondral defects that meet these size requirements.

His main rule of thumb: “If you have an osteochondral defect that is greater than 3 cm in diameter and 1 cm in depth, then you have to think about [osteochondral] allograft tissue. And you have to think about doing an osteotomy if there is an associated deformity [in any of these scenarios].”

In cases using osteochondral allografts for large post-traumatic knee defects, Gross said he performs realignment osteotomy about 60% of the time to offload the transplant.

Common scenarios

The two most common scenarios for performing an osteotomy with the allograft are a valgus knee with an old tibial plateau fracture and a varus knee with a medial femoral condyle defect, “which may be post-traumatic or a large area of osteochondritis dissecans,” Gross said.

In the first scenario, that of a valgus knee, “we do a lateral tibial plateau allograft, often with a meniscal allograft, done in conjunction with a distal femoral varus osteotomy,” Gross said.

The second scenario of the varus knee calls for realigning the proximal tibia with an osteotomy and a medial femoral condylar graft.

Gross’ technique for performing an osteotomy has changed in the last three years. “On the tibial side, with regards to our osteotomy, we are now doing opening wedge osteotomies … so we are no longer doing closing wedge osteotomies, unless it’s a very large deformity,” he said. “On the femoral side we are still doing closing wedge osteotomies.”

This patient had a severe valgus deformity from a plateau fracture. The right-hand image shows his knee at 12 years after osteotomy and plateau allograft implantation. This young patient had a large defect that only an osteochondral allograft could fill, Gross said. The image on the right shows the patient 10 years after a valgus proximal tibial osteotomy and implantation with a medial femoral condylar allograft. Images: Gross AE

Long-term evidence

His foundation for these operating guidelines is based on two long-term studies.

In the first study from 2001, researchers evaluated patients who underwent distal femoral osteochondral allografts at an average 10 years’ follow-up.

The average patient age was 27 years. Gross found a 95% Kaplan-Meier survivorship at five years, 85% survivorship at 10 years and 75% at 15-year follow-up.

Previous studies

He found similar results in a 2003 study that evaluated patients who underwent tibial plateau osteochondral allografts. The patient group was slightly older, but they had a longer average follow-up of 12 years, Gross said.

“At least 60% had a meniscal allograft and 60% also had an osteotomy,” Gross said. “Our survivorship at five years was 95%; 10 years was 85% and at 15 years it starts to drop off to 71%. But these were pretty badly beat-up knees.”

In failed allografts that require total knee replacement, Gross said, “The grafts themselves have no negative impact on total knee replacement. The osteotomy has the usual affected disadvantages, but the graft … actually restores bone stock for total knee replacement.”

For more information:

• Aubin PP, Cheah HK, Davis AM, et al. Long-term follow-up of fresh femoral osteochondral allografts for post-traumatic knee defects. Clin Orthop. 2001;No.391S:S318-S327.
• Gross AE. Cartilage resurfacing: Temporal or enduring solutions? #27. Presented at the 7th Annual Current Concepts in Joint Replacement Spring 2006 Meeting. May 21-24, 2006. Las Vegas.
• Shasha N, Krywulak S, Backstein D, et al. Long-term follow-up of fresh tibial osteochondral allografts for failed tibial plateau fractures. J Bone Joint Surg (Supplement 2). 2003;85-A:33-39.