[The unstable elbow joint]

[Results after Judet radial head prosthesis for non-reconstructable radial head fractures]

BACKGROUND

With regard to the treatment of non-reconstructable radial head fractures, both the resection and the implantation of a prosthesis are considered. Various studies have shown poor results concerning the resection of the radial head with accompanying osteoligamentous injuries. Due to these experiences, different types of prosthesis have been developed. However, the majority of them were not convincing. Judet developed a type of a bipolar prosthesis which had been modeled on the anatomy of the radial head. The aim of our retrospective study consists in examining the results of the Judet prosthesis.

PATIENTS AND METHODS

Between 1995 and 2007, 50 patients were treated with an arthroplasty. These were, corresponding to the classification by McKee and Jupiter, 19 type III and 31 type IV fractures. Thirty patients were available for a follow-up after 2.5 years on average.

RESULTS

According to the Morrey Score, 16 very good, 7 good, 3 fair and 4 bad results could be obtained. Following the criteria of Radin and Riseborough, 17 patients achieved a good, 9 a fair and 4 a bad result. The complications which appeared were: one patient with aseptic loosening, one patient with luxation of a prosthesis, one persistent radial joint instability, three patients with heterotopic ossification and four patients with protrusion relative to the capitulum humeri.

Locking reconstruction double plating of distal humeral fractures: how many screws in the distal ulnar column segment in A3 fracture provide superior stability? A comparative biomechanical in vitro study

OBJECTIVES

Two 90-degree configurations of locking reconstruction plates with different numbers of screws in the distal ulnar column segment of distal extra-articular humeral fractures with metaphyseal comminution (A3) were biomechanically investigated.

METHODS

Eight pairs of fresh-frozen human humeri were used. For paired comparison, the humeri were divided into 2 randomized groups. In both groups, double-plate osteosyntheses with locking reconstruction plates were performed in 90-degree configurations. In group 1, the posteriorly placed radial column plate exceeded the capitellum and the ulnar column plate extended into the ulnar sulcus. The ulnar plate was molded around the medial epicondyle and fixed with 3 short angular stable screws distally. In group 2, the posteriorly placed radial column plate was applied analogous to group 1. The locking reconstruction plate placed on the ulnar column was used reaching to the ulnar epicondyle, fixed with 1 long, angular, stable screw in the distal fragment. Stiffness testing for axial load and bending in static and cyclic tests were performed. In static test mode, a load was applied with a frequency of 0.1 Hz. For cyclic loading conditions, a load was applied at 1 Hz for 5000 cycles.

RESULTS

All tested specimens adequately resisted simulated physiologic loading conditions with no failure. Comparable stiffness values for axial load (P = 0.161) and significant lower stiffness values for bending (P = 0.017) in group 2 under static bending conditions were found. Considering cyclic loading conditions, no significant alterations in stiffness in each group under axial load occurred. In bending conditions, stiffness values for group 2 were significantly lower than that for group 1 (P = 0.036).

CONCLUSIONS

Under static and cyclic bending conditions, stiffness in group 2 was significantly lower than that in group 1. Nevertheless, both implant configurations showed no failure of the constructs. Based on these data, when applying locked plates in the clinical setting, more than 1 locked screw applied into the distal ulnar column of the articular segment is recommended.