Evaluation of the milling technique on the component-bone interface in the TATE elbow

To determine whether the surgeon can influence the accuracy of milling during the TATE elbow arthroplasty by applying force to the milling arm during the milling procedure.

In vitro study on Sawbone specimens.

Thirty identical solid foam models of the canine right humerus, elbow joint, and antebrachium (size large).

TATE elbow arthroplasty was performed on 30 elbows equally divided into 3 types of forces applied to the milling arm: (1) no force, (2) a maximally converging force, and (3) a maximally diverging force using the center of rotation post as a reference point. The resulting component-bone interface and post fit were quantified with digital photography.

The component-bone interface gap differed between techniques for most angles. The application of convergent or divergent milling forces frequently increased the component-bone interface gap. Post fit was also influenced by the milling technique, application of a convergent or divergent milling force affecting the fit of multiple posts. Interface gaps tended to be greater on the lateral aspect, an area that is not visible to the surgeon intraoperatively.

In this bone model study, application of convergent or divergent forces during milling frequently resulted in greater component-bone interface gaps and poorer post fit than when a neutral position was maintained.

Surgeons may affect implant fit within the constraints of the current arthroplasty system if they do not maintain a neutral position during milling. Greater component-bone interface gaps and poorer post fit may affect component osseointegration and lead to aseptic implant loosening.