Is Capitate Shift Reliable as a Single Indicator for Failure of Non-operative Management in Distal Radius Fractures?

Background Distal radius fractures (DRFs) are the most commonly treated fracture; however, their treatment remains controversial. There is significant variation in the rate of surgical intervention related to a lack of consensus regarding the displacement threshold for surgery. Although studies have advocated that carpal malalignment is the most important radiographic parameter for surgical correction, it is rarely considered in general clinical practice and remains poorly studied. Recently, capitate shift was identified as the most useful measure of carpal malalignment, and a capitate shift threshold of -5.98 mm was proposed to indicate surgical intervention. This study aimed to investigate if this threshold is associated with the failure of non-operatively managed DRFs and should be used as a threshold for primary surgical intervention. Methodology A retrospective analysis was performed of all adult patients who underwent closed manipulation and cast immobilisation for DRFs in a UK district general hospital between September 2021 and February 2022. Capitate shift was measured on initial post-casting radiographs using the validated capitate-to-axis-of-radius distance (CARD) by a junior surgeon. The outcome measure was the failure of conservative management, which was defined as the need for repeat intervention (i.e., cast reapplication or surgical fixation) following closed reduction and cast immobilisation. Results A total of 64 patients with 65 DRFs (16 (25%) male, 49 (75%) female) were included in the study. The mean age was 66.6 years (SD = 17.9, 95% CI = 62.2 to 70.9). The mean capitate shift was -1.51 mm (SD = 5.05, 95% CI = -0.28 to -2.73) in all cases (n = 65). The failure rate of DRFs with an 'unacceptable' capitate shift (i.e., equal or less than -5.98 mm) compared to those with an 'acceptable' capitate shift (i.e., greater than -5.98 mm) was 16.7% versus 3.8% (p = 0.09). Conclusions The study concluded that there was no significant association between a capitate shift threshold of -5.98 mm and failure of non-operatively managed DRFs. Given the ease of use and reliability of capitate shift, we advocate for multicentre large cohort studies to identify a threshold for surgical intervention and establish its association with functional outcomes.