Surgical Technique Considerations for Osteochondral Grafts

Surgical Technique Considerations for Osteochondral Grafts

Abstract & Commentary

Synopsis: Osteochondral autograft transplantation (OATS) is a surgical technique used for reconstruction of cartilage defects or osteochondral defects in the knee. This study characterizes the donor and recipient sites with respect to articular cartilage contact pressure, articular surface curvature, and cartilage thickness.

Source: Ahmad CS, et al. Biomechanical and topographic considerations for autologous osteochondral grafting in the knee. Am J Sports Med. 2001;29(2):201-206.

This study characterizes osteochondral donor and recipient sites with respect to articular cartilage contact pressure, articular surface curvature, and cartilage thickness. Five fresh-frozen cadaveric knees were evaluated with stereophotogrammetry, and kinematic data were obtained for flexion angles from 0-110°. Potential donor sites in the intercondylar notch, lateral trochlear ridge, and proximal-medial trochlear ridge demonstrated small areas of low-contact pressure (relatively nonweightbearing). However, donor sites in the distal-medial trochlear ridge were completely nonweightbearing. The medial and lateral trochlea curvatures best matched the medial and lateral femoral condyle recipient sites. The intercondylar notch donor sites best matched the curvature of the central trochlea. The cartilage thickness for each of the donor sites was very similar, with an average of 2.1 mm, while the average thickness of the recipient sites was 2.5 mm.

Ahmad and colleagues suggest graft harvest from the medial or lateral trochlear ridge for femoral condyle lesions in order to match surface curvature. They prefer using the distal-medial trochlea area since this study showed no weightbearing contact at all during range of motion from 0-110°. For lesions in the trochlea, they suggest using the intercondylar notch as the preferred donor site.

Comment by Stephen B. Gunther, MD

Cartilage lesions that cause symptoms such as pain, swelling, or locking may require operative treatment. The clinical prognosis for these lesions depends upon the size, depth, and location of the defect. Also, the chronicity of the lesion and the quality of the surrounding cartilage are important. There are multiple surgical options for treatment of chondral lesions such as abrasion arthroplasty, microfracture, autologous chondrocyte implantation, autologous osteochondral transplantation, and allograft implantation. This study evaluates the technical factors associated with matching donor osteochondral plug autografts to minimize morbidity and maximize anatomic replacement of host anatomy.

The surface contact area and pressure, measured with stereophotogrammetry, demonstrate that certain areas (intercondylar notch, lateral trochlear ridge, and proximal-medial trochlear ridge) have only limited weightbearing, and that the distal-medial trochlear ridge is completely nonweightbearing. This is important information that will allow surgeons to minimize donor site morbidity by avoiding graft harvest from weightbearing areas. Also, Ahmad et al measured important clinical parameters for matching surface contour and articular cartilage depth. They therefore conclude that the best donor site for femoral condyle lesions is the distal medial trochlear ridge, and the best donor site for a central trochlea lesion is along the intercondylar notch. These data compliment another study in the same journal issue by Bartz et al, which measured the topographic anatomical relationships between condylar lesions and graft sites. They also concluded that the most medial or lateral aspects of the trochlear area adjacent to the intercondylar notch, which they named "medial and lateral edge of the patellar groove," offers the best contour for osteochondral grafting to the medial or lateral femoral condyle.¹

Reference

1. Bartz RL, et al. Topographic matching of selected donor and recipient sites for osteochondral autografting of the articular surface of the femoral condyles. Am J Sports Med. 2001;29(2):207-212.