Positive arthrogram or arthroscopic exam

ity, nondissociative midcarpal instability, TFCC injury, ulnar impaction syndrome, pisotriquetral injury, and ECU subluxation.

Midcarpal instability often produces a painful clunk with ulnar deviation, but antecedent trauma is rarely reported. Provocative LT maneuvers are negative. A "catch-up clunk" may be demonstrable during motion of a loaded wrist from a radial to an ulnar deviated position, resulting in a sudden extension of the lunate and scaphoid in this condition as joint contact forces them to "catch up" to the already extended triquetrum. Cineradiography is useful to examine the synchronicity of proximal row kinetics to differentiate midcarpal from LT instability, the latter demonstrating the "clunk" arising from sudden extension of the scaphoid and lunate alone during ulnar deviation, dissociated from the triquetrum.

TFCC tears can mimic LT instability with an analogous injury history and symptomatic clicking. Provocative LT tests are negative, whereas distal radioulnar joint (DRUJ) and TFCC provocative tests are positive. In some cases, coincident LT and TFCC pathology is demonstrated by arthrography or arthroscopy. Isolated TFCC injury is best visualized by MRI or arthroscopy.

Ulnocarpal impaction syndrome is the result of excessive ulnar positive variance. Pain and weakness with rotational motion are noted. A standard neutral postero-anterior (PA) wrist radiograph will demonstrate ulna positive variance and "kissing" degenerative cysts and sclerosis at the lunate and ulna head. LT and TFCC tears are frequently associated findings. Arthrography or arthroscopy can assess LT and TFCC integrity prior to undertaking an ulnar shortening procedure.

A pisiform fracture may present after acute hypothenar trauma. This is best visualized with a supination oblique or carpal tunnel view radiograph. Radial-ulnar deviation may be painful, but specific LT provocative tests are negative. Pain and crepitance may be found by pisiform compression and translation.

Subluxation of the extensor carpi ulnaris tendon produces an audible snap as the forearm is actively supinated and the wrist is slightly flexed and ulnar deviated. LT provocative maneuvers are negative.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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