Radial Head and Related Instability and Contracture of the Forearm
Reference: Hotchkiss, Robert N., AAOS Instructional Course Lectures, Volume 47, 1998
The previous classification system of Mason is revised by the author. Maintenance of radial length by either reconstruction or replacement of the radial head is critical in the presence of longitudinal injury. Despite this, the treatment of the type III radial head fracture in this setting is difficult.
Points of Interest
“The debate concerning the incidence of pathologic forearm instability after radial head excision has never been fully settled in the literature.”
– once the radius rests 1 cm proximal to the ulna, wrist pain and loss of grip strength and motion are common. The distal ulna rides dorsally and mechanically blocks supination
– the radial head bears load at the radiocapitellar joint, with contact pressures increasing in extension and pronation. Supination seems to increase the stiffness of the interosseous membrane/ligament
Modified Mason Classification
– Type I: minimally displace, no mechanical block, treated nonoperatively
– Type II: 2 mm displacement or more, possibly mechanical block
– treatment is most controversial.
– if no mechanical block – treat like a type I
– if mechanical block – ORIF in young high demand or excision in elderly low demand
– if with longitudinal injury – better do all you can to fix or replace it
On metal replacement – no long term studies have been performed on titanium implants – these are hard to insert because of the rigid stem. Silicone is definitely not a great substance.
Remember to reconstruct or repair the posterolateral collateral ligaments if prosthesis is used.
If fixing the posterolateral complex, protect it by pronating the forearm
Not many great conclusions come from this paper, other than to say that type II and III injuries are best fixed or replaced with longitudinal injuries. Hotchkiss writes the chapter in Rockwood and
Green on these injuries, and is far more pessimistic about the results of treatment in this particular scenario. He feels that the interosseous ligament will never heal, that silicone does not maintain radial length (though he uses it), and that even cross-pinning of the radius to ulna does not, over the long term, prevent shortening.