Distal radius fracture arthroscopic intraarticular displacement measurement after open reduction and internal fixation from a volar approach.

BACKGROUND

The purpose of this study was to assess articular surface reduction arthroscopically after volar locked-plate fixation of distal radius fractures (DRFs) via fluoroscopyguided open reduction/internal fixation. We also aimed to develop preoperative radiographic criteria to help assist in determining which DRFs may need arthroscopic evaluation.

METHODS

A total of 31 consecutive patients with DRF were prospectively enrolled. Posteroanterior (PA) and lateral radiographs as well as axial, coronal, and sagittal CT scans were obtained just after attempted reduction of the DRF. The widest articular displacement at the radiocarpal joint surface of the distal radius (preopD) was then measured using a digital radiography imaging system. The DRF was reduced under fluoroscopy, and a volar locked plate was applied. The degree of residual articular displacement was then measured arthroscopically, and the maximum displacement (postopD) was measured with a calibrated probe.

RESULTS

Of the 31 patients, 7 had an arthroscopically assessed maximum postopD of > or = 2 mm after internal fixation. The correlation coefficients between each preopD and postopD of all radiographs and CTs were statistically significant. The cutoff values were 0.5 mm for PA radiographs, 2.10 mm for lateral radiographs, 2.15 mm for axial CT scans, 3.15 mm for coronal CT scans, and 1.20 mm for sagittal CT scans. All cutoff values for PA and lateral radiographs and for axial, coronal, and sagittal CT scans were unsuitable as screening criteria for arthroscopic reduction of DRF because of their low sensitivities and specificities. The cutoff value of the new preopD (the sum of the preopDs determined by lateral radiography and coronal CT scan) was 5.80 mm, and its sensitivity and specificity were 100% and 83.3%, respectively.

CONCLUSIONS

Because a new preopD cutoff value of 5.80 mm is a good indicator for residual articular displacement after internal fixation of >2 mm, it is also a good indicator for the need for arthroscopic evaluation after internal fixation.