Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

BACKGROUND: Alterations in talocrural joint arthrokinematics related to repositioning of the talus or fibula following ankle sprain have been reported in radiological and clinical studies. It is unclear if these changes can result from normal active ankle motion. The study objective was to determine if active movement created changes in the sagittal plane talofibular interval in ankles with a history of lateral ankle sprain and instability.
METHODS: Three subject groups [control (n = 17), ankle sprain copers (n = 20), and chronic ankle instability (n = 20)] underwent ultrasound imaging of the anterolateral ankle gutter to identify the lateral malleolus and talus over three trials. Between trials, subjects actively plantar and dorsiflexed the ankle three times. The sagittal plane talofibular interval was assessed by measuring the anteroposterior distance (mm) between the lateral malleolus and talus from an ultrasound image. Between group and trial differences were analyzed with repeated measures analysis of variance and post-hoc t-tests.
RESULTS: Fifty-seven subjects participated. A significant group-by-trial interaction was observed (F4,108 = 3.5; P = 0.009). The talofibular interval was increased in both copers [2.4±3.6 mm; 95% confidence interval (CI): 0.73-4.1; P = 0.007] and chronic ankle instability (4.1±4.6 mm; 95% CI: 1.9-6.2; P = 0.001) at trial 3 while no changes were observed in control ankle talar position (0.06±2.8mm; 95% CI: -1.5-1.4; P = 0.93).
CONCLUSIONS: The talofibular interval increased only in subjects with a history of lateral ankle sprain with large clinical effect sizes observed. These findings suggest that an alteration in the position of the talus or fibula occurred with non-weight bearing sagittal plane motion. These findings may have diagnostic and therapeutic implications for manual therapists.