Affected Elbow Sites May Be Suitable Graft Sources for Treatment of Capitellar Osteochondritis Dissecans
Key findings
- A popular treatment for osteochondritis dissecans of the elbow is to repair the capitellum by transplanting osteochondral plugs from the knee or rib to the elbow, which can create complications
- This study of cadaver specimens demonstrated histologic similarities between the capitellum and two alternative donor sites in the ipsilateral elbow: nonarticulating cartilage in the radial head and the olecranon tip
- The average difference in cartilage thickness between the capitellum and radial head was 0.2 mm; the average difference between the capitellum and olecranon tip was 0.4 mm
- All three sites had a convex articular surface
- Most other histologic features were similar between the capitellum and the proposed donor sites, including tissue and cell morphologies, proteoglycan content and surface architecture
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For adolescent and young adult athletes with advanced osteochondritis dissecans of the elbow, repair of the capitellum with osteochondral autologous transplantation is usually successful with regard to pain relief, elbow function and return to sports. However, the graft harvesting is done at the knee or rib, which can create its own complications that burden these young people.
Published in Knee Surgery, Sports Traumatology, Arthroscopy, Luke S. Oh, MD, orthopaedic surgeon, of the Sports Medicine Center at Massachusetts General Hospital, and colleagues found in a systematic review of 190 patients that 7.8% developed knee pain or locking after harvesting was done from the knee, and one patient developed pneumothorax after harvesting from the rib.
Dr. Oh's team speculates that two sites within the already affected elbow joint might be better sources for grafts: the nonarticulating part of the radial head and the nonarticulating lateral side of the olecranon tip.
In a previous study in Arthroscopy, they observed with computed tomography that the articular surfaces of both these sites are topographically matched to that of the capitellum. In their new research, Dr. Oh and colleagues further determined that the articular surfaces of the two alternative donor sites match that of the capitellum in terms of histologic features. They published their findings in Arthroscopy.
Study Details
The researchers collected 10 human cadaveric elbow specimens, along with a matching ulna for four of them. They obtained osteochondral grafts from the capitellum, the nonarticulating part of the radial head, and where available, the nonarticulating lateral side of the olecranon tip.
Two pathologists assessed cartilage thickness, the shape of the articular surface and parameters specified by the International Cartilage Repair Society (ICRS) for histologic scoring of cartilage repair, including tissue and cell morphologies, proteoglycan content and surface architecture. Because only four olecranon specimens were available, they were excluded from statistical analyses.
The researchers found the following:
- Cartilage thickness: 1.5 mm at the capitellum, 1.3 mm at the nonarticulating part of the radial head (P = NS) and 1.9 mm at the lateral side of the nonarticulating olecranon tip
- Shape of the articular surface: convex at all sites
- ICRS parameters: Among 13 features, the only significant differences were: (a) there was less chondrocyte clustering at the capitellum than in the radial head and (b) mid-/deep-zone assessment of the capitellum scored higher than that of the radial head
A Foundation for Clinical Research
The measures evaluated in this study are considered general determinants of cartilage health. From a histologic point of view, there seem to be no obstacles to using grafts from the nonarticulating part of the radial head and the nonarticulating lateral side of the olecranon tip when reconstructing the capitellum.
Before proceeding to clinical studies, the researchers plan to continue with cadaveric studies to refine surgical techniques and instrumentation. It will then be important to establish in vivo whether harvesting from the ipsilateral elbow negatively affects elbow function and how nonarticulating cartilage will perform when transplanted to an articulating part of the joint.
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