Diagnostic Studies

Anteroposterior, lateral, and oblique radiographs of the wrist were normal. An arthrogram was obtained (Fig. 64—1).

Relative malalignment between the lunate and the triquetrum may be apparent on lateral radiographs. Bisectors of the lunate and triquetrum intersect to form an LT angle (normal = 14 degrees, range —3 to +31 degrees). Patients with LT dissociation will exhibit a negative angle (mean value = —16 degrees). A volar intercalated segmental instability (VISI) pattern is present in some (chronic) cases.

Radial deviation and clenched-fist anteroposterior views can be useful. Palmar flexion of the scaphoid and lunate without movement of the triquetrum confirms the loss of proximal row integrity.

Arthrography is a useful imaging tool for LT instability. Passage of dye through the LT interspace documents the presence of a perforation, tear, or dissociation. Age-related LT perforations and tears have been frequently demonstrated in asymptomatic individuals. Therefore, arthrogram findings require clinical correlation. A videotaped arthrogram with motion sequences demonstrating abnormal dye pooling associated with abnormal proximal row kinetics is useful as a confirmatory study.

Bone scans, tomograms, and magnetic resonance imaging (MRI) have limited utility in the setting of LT instability. Standards for MRI of LT ligaments are not yet available.

Ligament Tear
Essentials of Human Physiology

Essentials of Human Physiology

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