Rotational stability for intercarpal fixation is enhanced by a 4-tine staple.

PURPOSE: To compare the torsional stability of 6 fixation techniques for intercarpal fixation including a 4-tine, in-line staple.

METHODS

We chose the scapholunate interval as the test site for rotational stability for various constructs. We used 42 pairs of embalmed scaphoids and lunates for the comparisons and created 6 construct groups. Fixation of the scapholunate gap was performed with a 3-mm screw, 2 1.1-mm (0.045-inch) K-wires spaced 2 mm apart, or 2 1.1-mm K-wires spaced 5 mm apart. One member of each pair was fixed with either a standard 2-tine peripherally placed staple or a customized 4-tine staple. Each scapholunate construct was tested in torsion to failure on a biaxial materials testing machine.

RESULTS

In all cases, the 4-tine staple significantly increased rotational stability. The 2-tine staple resulted in statistically insignificant increases in rotational stability. With central fixation alone, K-wires separated by 5 mm showed the greatest resistance to torsion, and the 3-mm screw showed the least.

CONCLUSIONS

Use of an in-line, 4-tine staple provided increased rotational stability and may result in enhanced healing of intercarpal ligamentous reconstructions and arthrodeses.

CLINICAL RELEVANCE: A 4-tine staple compared with a standard staple provided superior rotational stability for intercarpal fixation.