Joy C. Vroemen

Computer-Assisted Planning and Navigation for Corrective Distal Radius Osteotomy, Based on Pre- and Intraoperative Imaging

Malunion after a distal radius fracture is very common and if symptomatic, is treated with a so-called corrective osteotomy. In a traditional distal radius osteotomy, the radius is cut at the fracture site and a wedge is inserted in the osteotomy gap to correct the distal radius pose. The standard procedure uses two orthogonal radiographs to estimate the two inclination angles and the dimensions of the wedge to be inserted into the osteotomy gap. However, optimal correction in 3-Dspace requires restoring three angles and three displacements. This paper introduces a new technique that uses preoperative planning based on 3-D images. Intraoperative 3-D imaging is also used after inserting pins with marker tools in the proximal and distal part of the radius and before the osteotomy. Positioning tools are developed to correct the distal radius pose in six degrees of freedom by navigating the pins. The method is accurate (derr <; 1.2 mm, φerr <; 0.9°, mTRE = 1.7 mm), highly reproducible (SEd <; 1.0 mm, SEφ ≤ 1.4°, SEmTRE = 0.7 mm), and allows intraoperative evaluation of the end result. Small incisions for pin placement and for the osteotomy render the method minimally invasive.

Three-dimensional assessment of bilateral symmetry of the radius and ulna for planning corrective surgeries.

PURPOSE The contralateral unaffected side is often used as a reference in planning a corrective osteotomy of a malunited distal radius. Two-dimensional radiographs have proven unreliable in assessing bilateral symmetry, so we assessed 3-dimensional configurations to assess bilateral symmetry. METHODS We investigated bilateral symmetry using 3-dimensional imaging techniques. A total of 20 healthy volunteers without previous wrist injury underwent a volumetric computed tomography of both forearms. The left radius and ulna were segmented to create virtual 3-dimensional models of these bones. We selected a distal part and a larger proximal part from these bones and matched them with a mirrored computed tomographic image of the contralateral side. This allowed us to calculate the relative displacements (Δx, Δy, Δz) and rotations (Δφx, Δφy, Δφz) for aligning the left bone with the right bone segments. We investigated the relation between longitudinal length differences in radiuses and ulnas. RESULTS Relative differences of the radiuses were (Δx, Δy, Δz): -0.81 ± 1.22 mm, -0.01 ± 0.64 mm, and 2.63 ± 2.03 mm; and (Δφx, Δφy, Δφz): 0.13° ± 1.00°, -0.60° ± 1.35°, and 0.53° ± 5.00°. The same parameters for the ulna were (Δx, Δy, Δz): -0.22 ± 0.82 mm, 0.52 ± 0.99 mm, 2.08 ± 2.33 mm; and (Δφx, Δφy, Δφz): -0.56° ± 0.96°, -0.71° ± 1.51°, and -2.61° ± 5.58°. There is a strong relation between absolute length differences (Δz) between the radiuses and ulnas of individuals. CONCLUSIONS We observed substantial length and rotational differences around the longitudinal bone axis in healthy individuals. Surgical planning using the unaffected side as a reference may not be as useful as previously assumed. However, including the length difference of the adjacent forearm bones can be useful in improving length correction in computer-assisted planning of radius or ulna osteotomies and in other reconstructive surgery procedures. CLINICAL RELEVANCE Bilateral symmetry is important in reconstructive surgery procedures where the contralateral unaffected side is often used as a reference for planning and evaluation.

Patient-specific distal radius locking plate for fixation and accurate 3D positioning in corrective osteotomy

Preoperative three-dimensional planning methods have been described extensively. However, transferring the virtual plan to the patient is often challenging. In this report, we describe the management of a severely malunited distal radius fracture using a patient-specific plate for accurate spatial positioning and fixation. Twenty months postoperatively the patient shows almost painless reconstruction and a nearly normal range of motion.

Three-Dimensional Computer-Assisted Corrective Osteotomy Techniques for the Malunited Distal Radius

A corrective osteotomy is a frequently required procedure for symptomatic malunions of the distal radius. A multitude of different methods have been proposed for correction of distal radius malunions. However, precise correction of a severe malunion that requires simultaneous adjustment of displacement and rotation in multiple planes remains a challenge. Technological advancements have resulted in improved techniques to perform radial corrective osteotomy. In the last few decades a number of computer-assisted techniques have been proposed. Computer-assisted surgery with the use of threedimensional (3D) pre-operative planning offers multiple advantages. 3D imaging and reconstructions are more intuitive and show details that cannot be observed from twodimensional (2D) radiographs. This chapter describes and discusses current techniques in computer-assisted corrective osteotomy techniques of the malunited distal radius.