Kinematic "4 Dimensional" CT Imaging in the Assessment of Wrist Biomechanics Before and After Surgical Repair

Abstract

Aim: Describe the use of 320 row detector CT scanner for 4 Dimensional CT acquisition on a specialized platform designed for wrist kinematic evaluation and to demonstrate the utility of 4 Dimensional CT in the assessment of wrist biomechanics before and after surgical repair.

Materials and methods: Six wrists (1 volunteer and 4 patients) were uniformly imaged with conventional X-rays and 4 Dimensional CT on a 320 row detector CT scanner (Aquilion one, Toshiba, Tokyo, Japan). A dedicated custom designed wrist platform was used for kinematic imaging. Three subjects (3 wrists) had prior fixation of the complex wrist injury. Clinical correlations were obtained.

Results: All subjects were successfully scanned in various wrist motions. 4 Dimensional CT image quality was adequate and carpal kinematic behavior was easily assessed in various wrist motions both before and after surgical repair. The normal and altered carpal kinematic behaviors correlated well with the clinical findings. In the operated wrists, while X-rays demonstrated slight gapping after scapholunate ligament repair, kinematic imaging demonstrated no abnormal widening on dynamic motion and showed normal dorsally hinged "scissoring" type scapholunate motion with active wrist motion. However, normal mid-carpal initiated wrist motion on flexion/extension was replaced by radiocarpal initiated motion, likely because of midcarpal stiffness/scarring.

Conclusion: 4 Dimensional CT provides adequate and novel assessment of wrist biomechanics both before and after surgical repair.

Figure 1a, b

Dedicated “in CT” wrist platform. Pictures taken during unconstrained flexion and extension motions.

Figure 2a, b

A 62-year-old man with prior ORIF and SLIL ligament repair. Normal SL space (arrow) on posteroanterior X-ray view (a). Notice mild gaping of S-L interval (arrow) on clenched fist posteroanterior X-ray view (b). ORIF indicates open reduction internal fixation; SLIL, scapholunate interosseus ligament.

Figure 3a, b.

A 50-year-old woman with prior ORIF and SLIL ligament repair. Normal SL space (arrow) on posteroanterior X-ray view (a). Notice mild gaping of S-L interval (arrow) on clenched fist posteroanterior X-ray view (b). ORIF indicates open reduction internal fixation; SLIL, scapholunate interosseus ligament.

Figure 4

A 30-year-old man with prior ORIF and SLIL ligament repair. Notice mild gaping of S-L interval (arrow) on conventional posteroanterior X-ray view. ORIF indicates open reduction internal fixation; SLIL, scapholunate interosseus ligament.

Figure 5

A 45-year-old man with diffuse wrist pain. Outside plain films not available. 2D reconstructions from the kinematic 4D CT volume scan show ulnar sided carpal translocation bilaterally. Also note subchondral cystic changes of ulna bilaterally (arrows) suggesting dynamic ulnocarpal abutment.