Total Wrist Arthroplasty Alignment and Its Potential Association with Clinical Outcomes

Abstract

Purpose There is a lack of quantitative research that describes the alignment and, more importantly, the effects of malalignment on total wrist arthroplasty (TWA). The main goal of this pilot study was to assess the alignment of TWA components in radiographic images and compare them with measures computed by three-dimensional analysis. Using these measures, we then determined if malalignment is associated with range of motion (ROM) or clinical outcomes (PRWHE, PROMIS, QuickDash, and grip strength). Methods Six osteoarthritic patients with a single type of TWA were recruited. Radiographic images, computed tomography images, and clinical outcomes of the wrists were recorded. Using posteroanterior and lateral radiographs, alignment measurements were defined for the radial and carpal components. Radiographic measurements were validated with models reconstructed from computed tomography images using Bland-Altman analysis. Biplanar videoradiography (<1mm and <1 degree accuracy) was used to capture and compute ROM of the TWA components. Linear regression assessed the associations between alignment and outcomes. Results Radiographic measures had a 95% limit-of-agreement (mean difference ± 1.96 × SD) of 3 degrees and 3mm with three-dimensional values, except for the measures of the carpal component in the lateral view. In our small cohort, wrist flexion-extension and radial-ulnar deviation were correlated with volar-dorsal tilt and volar-dorsal offset of the radial component and demonstrated a ROM increase of 3.7 and 1.6 degrees per degree increase in volar tilt, and 10.8 and 4.2 degrees per every millimeter increase in volar offset. The carpal component's higher volar tilt was also associated with improvements in patient-reported pain. Conclusions We determined metrics describing the alignment of TWA, and found the volar tilt and volar offset of the radial component could potentially influence the replaced wrist's ROM. Clinical Relevance TWA component alignment can be measured reliably in radiographs, and may be associated with clinical outcomes. Future studies must evaluate its role in a larger cohort.

Keywords: alignment; arthroplasty; outcomes; volar tilt; wrist.

Fig. 1

Posteroanterior view (PA, left panel) and lateral view (right panel) of the right hand of a subject with total wrist arthroplasty. Blue lines show the reference lines of the radial (R) and carpal components (C) and red lines show the reference lines of the third metacarpal and radius. For each component, radial tilt (+RU) and offset (perpendicular black arrows) were defined in PA view, and volar tilt (+VD) and offset (perpendicular black arrows) were defined in lateral view. In this figure, the radial and carpal components are tilted radially and dorsally.

Fig. 2

The orthogonal coordinate systems for the ( A ) radial component, ( B ) carpal component, ( C ) resected radius, and ( D ) the third metacarpal are shown as red (x-axis), green (y-axis), and blue (z-axis).

Fig. 3

Overall flexion–extension and radial–ulnar deviation range of motion (ROM) increases as the volar tilt of the radial component increases. Reconstructions from computed tomography scan illustrate alignments of indicated data points. An increase of 3.7 degrees flexion–extension and 1.6 degrees radial–ulnar deviation with each degree increase of volar tilt.

Fig. 4

Overall flexion–extension and radial–ulnar deviation range of motion (ROM) increases as the volar offset of the radial component increases. An increase of 10.8 degrees flexion–extension and 4.2 degrees radial–ulnar deviation for every millimeter increase of volar offset was observed.