Distance mapping in three-dimensional virtual surgical planning in hand, wrist and forearm surgery: a tool to avoid mistakes

Abstract

Purpose: Three-dimensional planning in corrective surgeries in the hand and wrist has become popular throughout the last 20 years. Imaging technologies and software have improved since their first description in the late 1980s. New imaging technologies, such as distance mapping (DM), improve the safety of virtual surgical planning (VSP) and help to avoid mistakes. We describe the effective use of DM in two representative and frequently performed surgical interventions (radius malunion and scaphoid pseudoarthrosis).

Methods: We simulated surgical intervention in both cases using DM. Joint spaces were quantitatively and qualitatively displayed in a colour-coded fashion, which allowed the estimation of cartilage thickness and joint space congruency. These parameters are presented in the virtual surgical planning pre- and postoperatively as well as in the actual situation in our cases.

Results: DM had a high impact on the VSP, especially in radius corrective osteotomy, where we changed the surgical plan due to the visualization of the planned postoperative situation. The actual postoperative situation was also documented using DM, which allowed for comparison of the VSP and the achieved postoperative situation. Both patients were successfully treated, and bone healing and clinical improvement were achieved.

Conclusion: The use of colour-coded static or dynamic distance mapping is useful for virtual surgical planning of corrective osteotomies of the hand, wrist and forearm. It also allows confirmation of the correct patient treatment and assessment of the follow-up radiological documentation.

Keywords: Hand; Osteotomy; Radius; Scaphoid bone; Software; Three-dimensional; Wrist.

Fig. 1

From DICOM to 3D model

Fig. 2

Malunited distal radius fracture dp and lat (6 months after trauma)

Fig. 3

Six months after corrective osteotomy dp and lat

Fig. 4

Conventional X-rays at 27 years dp and lat

Fig. 5

Initial virtual surgical planning. Top: registration process and planned osteotomy (purple: distal part; green: proximal part). Bottom: placement of the standard osteosynthesis plate and design of the surgical guide

Fig. 6

Simulation of the postoperative situation using distance mapping (dark red = 0 mm and light blue ≥ 5 mm distance). The dark red area indicates contact of the bones (ulna in the dorsal sigmoid notch and lunate in lunate fossa) which corresponds to a dorsal malposition of the ulna and lunate

Fig. 7

Virtual surgical planning of the derotational and shortening osteotomy of the ulna

Fig. 8

Planned position of the ulna (blue)

Fig. 9

Analysis pre- and postoperatively. A mirrored right side as reference for virtual surgical planning. B symptomatic left side (preoperative). C left side after virtually planned situation with uncentred (dorsally) contact area of the ulna in sigmoid notch as well as a dorsal translation of the lunate in lunate fossa (dark red areas). D final postoperative situation on the right which shows a centred position of the ulna and a homogenous distribution of the orange area in the lunate and scaphoid fossa of the radius

Fig. 10

Preoperative X-rays (dorsopalmar and lateral)

Fig. 11

Preoperative MRI scan (coronar T1)

Fig. 12

Preoperative planning using distance mapping and the mirrored opposite site

Fig. 13

Intraoperative situation with the 3D-printed guides in place (left: guide to place K-wires; right: reposition guide to maintain parallel alignment of the K-wires)

Fig. 14

Intraoperative fluoroscopy; upper line: placed K-wires (left); repositioned scaphoid (middle and right), lower line: reconstructed scaphoid with iliac crest bone graft and CCS 3.0 screw

Fig. 15

CBCT with Sander's reconstructions 6 weeks postoperatively

Fig. 16

Postoperative analysis with distance mapping A homogenous distribution of the joint surface of the scaphoid (= corresponding joint surface of the removed capitate) indicates an anatomical reconstruction of the scaphoid. (left: radial view, right: ulno-palmar view capitate removed)