Midcarpal fusion: Complications and outcomes of endomedullary screws technique with three techniques: Four-corner, luno-capitate and bicolumnar fusion. Case series.

INTRODUCTION

We report the clinical and radiographic outcomes, and complications of midcarpal fusions, four corner fusion (4CF), bicolumnar (BC) and luno-capitate (LC), with a focus on endomedullary screw fixation.

METHODS

Between 2018 and 2024, 38 patients underwent three distinct types of midcarpal fusions: 20 underwent 4CF, 6 underwent BC and 12 underwent LC. Postoperative evaluation was conducted using X-ray and computed tomography scans to assess the degree of fusion, correction of the lunate and capitate bones, presence of possible screw prominences and secondary radio-carpal degeneration.

RESULTS

Twenty-six patients exhibited favourable outcomes, whereas 12 were reoperated: 3 cases were converted to total wrist fusion owing to screw migration in non-union, 4 cases for screw removal alone due to screw migration and the others for revision of the arthrodesis site. In 13 cases, a loss of reduction of the semilunar bone with consequent DISI was identified and was sometimes associated with a reduction in wrist extension.

CONCLUSIONS

Intramedullary screws have low intrinsic stability. Immobilisation is recommended for at least 6 weeks with caution during mobilisation to avoid stress on the healing site, minimise the risk of screw migration and loss of lunate reduction. Although DISI alone does not constitute a reason for surgical revision, it has the potential to limit wrist extension. In some cases, fusion may not be achieved; however, this does not necessarily constitute a problem. It is also advisable to use shorter screws, to avoid subchondral placement, owing to the possibility of secondary migration.

LEVEL OF EVIDENCE: IV.