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Incidence of Asymptomatic Scapholunate Widening on Plain Radiographs
Brook N Cahill, MD
1; Ashlyn J Morris, BA
1; Mirindi Kabangu, BS
1; Noor U Malik, BS
1; David Szames, DO
1; Lauren M Ladd, MD
1; Desai Khusboo, MD
1; Erin L Weber, MD, PhD
21Indiana University, Indianapolis, IN; 2Indiana University School of Medicine, Indianapolis, IN
Scapholunate (SL) widening on plain view films can indicate an injury to the scapholunate ligament. Radiographic findings such as increased SL width (>3 mm) and SL angle (>60°) can be pathognomonic. SL dissociation is thought to alter wrist kinematics leading to carpal instability and ultimately painful arthritis. The aim of this study was to identify the incidence of asymptomatic extremities that had SL widening on plain film x-rays. Secondary findings were the SL gap, SL angle, and SLAC stage.
In a retrospective review, radiographs with findings of ‘scapholunate widening' from September 2020 to October 2023 were identified. Demographic data, comorbidities, study indications, and surgical history were collected. Patients were identified as asymptomatic from clinical notes and indication of x-ray study (e.g., CMC arthritis, fracture, or infection). SL gap and angle were measured by two radiologists who also determined SLAC stage.
A total of 717 radiographs were identified. Studies (n= 271) were eliminated due to erroneous reports (n= 86), poor radiograph quality (n= 82), or repeat examinations of the same extremity (n= 103). The remaining radiographs included 446 extremities, of which, 52 had undergone a procedure to address an SL injury. A total of 394 (88.3%) extremities with evidence of SL widening did not have an operation. Of these non-operative extremities, 258 (65%) were considered asymptomatic while 136 (35%) extremities were deemed symptomatic. Overall incidence of asymptomatic extremities was 58%. The average SLAC stage in the asymptomatic group was less at 1.7 ± 0.9 versus 2.0 ± 1.2 in the symptomatic group (
p < 0.05). The average SL width was less in the asymptomatic group at 4.3 ± 1.7 mm compared to 5.0 ± 2.4 mm in the symptomatic group (
p < 0.005). The average SL angle in the asymptomatic group was 66.3 ± 15.4° compared to 64.7 ± 17.3°, which was not statistically significant.
SL widening on x-ray is not an infrequent finding. Our overall incidence of asymptomatic SL widening on plain radiographs was 58% for all studies but as high as 65% in non-operative extremities. Only 11.7% of extremities with a radiographic finding of SL widening underwent a procedure to address an SL injury. Asymptomatic patients had significantly lower SLAC stage and SL gap, while SL angle was not significantly different between the groups. It will be interesting to follow the progression of patients in the asymptomatic group for the development of symptomatic arthritis.
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