Purpose
Comminuted radial head fractures are commonly treated by surgical resection or replacement
with a prosthesis. A potential problem with radial head replacement is overlengthening
of the radial neck (“overstuffing” of the radial head), which has been shown to affect
both ulnohumeral kinematics and radiocapitellar pressures. We hypothesized that an
overstuffed radial head prosthesis increases capitellar pressure and reduces coronoid
pressure.
Methods
Seven human cadaveric elbows were prepared on a custom-designed apparatus simulating
stabilizing muscle loads, and passively flexed from 0° to 90° under gravity valgus
torque while joint contact pressures were measured. Each elbow was tested sequentially
with different neck lengths, starting with the intact specimen followed by insertion
of understuffed (−2 mm), standard-height (0 mm), and overstuffed (+2 mm) radial head
prostheses in neutral forearm rotation, 40° pronation, and 40° supination positions,
respectively.
Results
Capitellar mean contact pressures significantly increased after insertion of an overstuffed
radial head prosthesis. In valgus position with neutral forearm rotation, capitellar
mean contact pressure on the joint with an intact radial head averaged 227 ± 70 kPa.
Insertion of understuffed, standard-height, and overstuffed radial head prostheses
changed the mean contact pressures to 152 ± 76 kPa, 212 ± 68 kPa, and 491 ± 168 kPa,
respectively. The overstuffed radial head group had significantly lower whole coronoid
mean contact pressures (153 ± 56 kPa) compared with the intact (390 ± 138 kPa) and
standard-height (376 ± 191 kPa) radial head groups.
Conclusions
An increase in radial prosthesis height significantly increases capitellar contact
pressures and reduces coronoid contact pressures.
Clinical relevance
Restoration of the anatomic radial head height is critical when performing radial
head arthroplasty to maintain normal joint biomechanics. Elevated capitellar contact
pressures can potentially lead to pain and early degenerative changes.
Key words
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Article info
Publication history
Published online: October 10, 2022
Accepted:
November 17,
2021
Received:
March 1,
2019
Publication stage
In Press Corrected ProofFootnotes
Dr O'Driscoll and the Mayo Foundation receive royalties from Acumed, LLC, Wright Medical, Inc, and Aircast, Inc. No benefits in any form have been received or will be received by the other authors related directly or indirectly to the subject of this article.
Identification
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© 2021 by the American Society for Surgery of the Hand. All rights reserved.
