Dart thrower's motion and the injured scapholunate interosseous ligament: A scoping review of studies examining motion, orthoses, and rehabilitation.
Jamie L Bergner, Jennifer Q Farrar, Rogelio A Coronado
PMID 30879716WHAT IT FOUND
In a torn scapholunate ligament, dart thrower motion may separate the scaphoid and lunate at end range, especially ulnar flexion.
Midrange motion may be safer, but cadaver and imaging studies did not test repaired ligaments, and orthosis designs are unproven.
Key findings
01In six subjects with scapholunate instability, the scaphoid moved 12.8 mm and the lunate moved 4.8 mm during dart thrower motion, and the gap was largest at end-range ulnar flexion.
02No biomechanical study examined dart thrower motion after scapholunate ligament repair or reconstruction.
03Pain resolution reported with a dynamic dart thrower orthosis occurred in a five-patient program that also included joint position sense training, isometric, eccentric, and concentric training, and co-activation and dynamic stability training, so the orthosis alone cannot be credited.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The review was a scoping review, not a pooled analysis of effect, and it did not formally assess study quality or risk of bias. It included case reports, case series, and expert opinion, so the evidence is low level. No randomized trials have been done on this topic. Biomechanical studies used cadaver wrists and may not capture live proprioceptive and neuromuscular control. The studies tested limited arcs of motion, and normal dart thrower motion varies widely between people and between sides. No biomechanical study tested the ligament after repair or reconstruction. Orthosis studies did not compare designs, did not consistently image the scapholunate gap, and did not report long-term outcomes. Rehabilitation outcomes came from small, multi-component programs, so the effect of dart thrower motion or an orthosis alone cannot be separated. The review included only English articles and did not contact authors or experts.
Declared interests
No funding source is reported, and the authors declared no conflicts of interest.
The easy way to misread this
Do not read the positive case reports as proof that dart thrower motion or a dart thrower orthosis works after scapholunate ligament repair. The review found no biomechanical study on repaired ligaments, and the reported improvements came from multi-component rehabilitation, so the orthosis alone cannot be credited.