Elsevier

Journal of Shoulder and Elbow Surgery

Volume 18, Issue 5, September–October 2009, Pages 779-784
Journal of Shoulder and Elbow Surgery

Basic Science and Elbow
Radiocapitellar joint stability with bipolar versus monopolar radial head prostheses

https://doi.org/10.1016/j.jse.2009.02.011Get rights and content

Background

Bipolar and monopolar designs are both available for replacement of the radial head. Few data exist comparing the biomechanical characteristics of these 2 quite different prostheses. This study evaluated the relative contribution to radiocapitellar stability by concavity compression with these 2 types of radial head prostheses.

Methods

The study used 12 fresh frozen elbow cadavers. The capitellum of the distal humerus and 3 different conditions of radial head (native, monopolar and bipolar) were tested for radiocapitellar joint stability.

Results

The monopolar metallic head and the native radial head behaved similarly regarding resistance to subluxation. The bipolar head behaved in an entirely opposite manner than the native and monopolar head and actually acted to facilitate subluxation.

Conclusions

Mobility of radial head components, such as in the bipolar radial head, has a compromising effect on the concavity compression stability of the radiocapitellar joint. A monopolar implant is more effective in stabilizing the radiocapitellar joint than a bipolar radial head prosthesis.

Level of evidence

Basic science biomechanical laboratory study.

Section snippets

Specimen preparation

The study used 12 fresh frozen elbows from deceased donors with no evidence of radiocapitellar joint pathology. The average of age of the donor at the time of death was 76 years (range, 61-93 years). Each specimen was thawed overnight at room temperature before preparation. All soft tissues, including the joint capsule, were carefully removed, and the radiocapitellar joint was completely separated. The distal humerus and proximal radius were resected from the upper extremity.

The specimens were

Results

The monopolar radial head and the native radial head both resisted subluxation (Figure 3). The force-displacement curves were generally characterized by a steep initial increment. As translation of radial head from the capitellum increased, the force resisting subluxation increased until a peak was reached. With the monopolar head, the curve demonstrated less stiffness compared with the native head. The bipolar head, however, demonstrated a mirror-image (opposite) pattern. The required force to

Discussion

Among the complications of radial head arthroplasty, dislocation of the prosthesis is serious and sometimes requires revision surgery. Brinkmanet et al4 reported 2 cases of revision surgery due to subluxation of the prosthesis among 11 patients who underwent bipolar radial head replacement. Gabrion et al5 reported 2 prosthesis dislocations in 10 patients treated with a bipolar radial head prosthesis. Another study of midterm results with bipolar prosthesis reported a patient who sustained

References (25)

  • L. Berglund et al.

    Four axial structural and material test machine

    Biomed Sci Instrum

    (1994)
  • J.M. Brinkman et al.

    Treatment of sequelae of radial head fractures with a bipolar radial head prosthesis: Good outcome after 1-4 years follow-up in 11 patients

    Acta Orthopaedica

    (2005)
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