Management of Pisotriquetral Instability.

Pisotriquetral instability is an often-overlooked condition that can lead to ulnar-sided wrist pain and dysfunction. Various case series and biomechanical studies have been published regarding the diagnosis and treatment of this condition. We review current methods for examining, diagnosing, and treating pisotriquetral instability.

Imaging and anatomic study of the pisiform bone/ulnar nerve relationship-evaluation of the preferred surgical approach for the excision of the pisiform bone.

This study examines the role of the pisiform bone/ulnar nerve relationship in determining the preferred surgical approach for the excision of the pisiform bone. An anatomic dissection of Guyon's canal on 10 fresh frozen cadaver wrists evenly divided between males and females was combined with magnetic resonance imaging (MRI) scans of 10 volunteer wrists. The 3 reported data points include the axial images determined on the MRI, the anatomic dissection related to the proximity of the ulnar nerve relative to the pisiform in defined positions of the wrist and the soft tissue envelope that surrounds the pisiform, and the proximity of the ulnar nerve as recorded, measured, and analyzed. An analysis of variance of the recorded data points was performed and the statistical results were presented (P value of P 05). Dissection and the MRI scans determined that the soft tissue envelope between the pisiform and ulnar nerve at Guyon's canal with neutral dorsiflexion was 2.5 mm. Palmar flexion was 3.0 mm and neutral flexion was 4.5 mm. The thinnest area was adjacent to the ulnar nerve proper on the volar radial aspect of the pisiform, on the basis of clock-faced analysis, between the 3 : 00 and 6 : 00 positions (the pisiform as a circle). The proximity of the pisiform in relation to the ulna and the limit of the soft tissue envelope would suggest that the preferred surgical approach, or that least likely to cause injury to the ulnar nerve, is one that is volar and includes excising the pisiform after exposing Guyon's canal.

Anatomy of the ulnar tunnel and the influence of wrist motion on its morphology.

PURPOSE: To examine the anatomy of the ulnar tunnel, with emphasis on the pisohamate arcade and pisohamate hiatus, and study the influence of wrist kinematics on the morphology of these structures. METHODS: Ten fresh-frozen cadaveric hands were dissected. The dimensions and relationships of the ulnar tunnel, pisohamate arcade, and pisohamate hiatus were recorded. The effect of 4 wrist positions on these dimensions and relationships was investigated. RESULTS: The ulnar tunnel has 3 compartments--proximal, middle, and distal relative to the pisiform-with variable morphologies, dimensions, and boundaries. In wrist neutral position, the length of the ulnar tunnel was 45 mm (range, 42 to 51 mm). The middle compartment was found to be the narrowest; the proximal, the widest, averaging 5.0 mm; and the pisohamate hiatus that separates the middle and distal compartments, highly dynamic. The length of the pisohamate arcade was 21.5 mm (range, 18.0 to 26.0 mm), and the length and width of the pisohamate hiatus were 11.0 mm (range, 9.8-11.5 mm) and 6.0 mm (range, 5.3 to 7.2 mm), respectively. During wrist extension, the ulnar nerve was under tension. Wrist flexion was the position that caused the most change in ulnar tunnel and pisohamate arcade and hiatus anatomy, causing the width of the proximal compartment to increase from 5.0 to 10.0 mm. During this motion, the shape of the pisohamate arcade changed from a C shape to linear, and the length increased to 24.5 mm (range, 19.3 to 28.5 mm). The pisohamate hiatus narrowed, its width decreased to 1.5 mm, and the deep branch of the ulnar nerve was somewhat compressed. CONCLUSIONS: The ulnar tunnel is a dynamic space with dimensions and relationships that are influenced by wrist motion. During ulnar tunnel surgery, all 3 compartments of the ulnar tunnel should be explored and decompressed, including the pisohamate hiatus, by releasing the pisohamate arcade.

Visualisation of the pisotriquetral joint through standard portals for arthroscopy of the wrist: a clinical and anatomical study.

Disorders of the pisotriquetral joint are well recognised as the cause of pain on the ulnar side of the wrist. The joint is not usually examined during routine arthroscopy because it is assumed to have a separate joint cavity to the radiocarpal joint, although there is often a connection between the two. We explored this connection during arthroscopy and in fresh-frozen cadaver wrists and found that in about half of the cases the pisotriquetral joint could be visualised through standard wrist portals. Four different types of connection were observed between the radiocarpal joint and the pisotriquetral joint. They ranged from a complete membrane separating the two, to no membrane at all, with various other types of connection in between. We recommend that inspection of the pisotriquetral joint should be a part of the protocol for routine arthroscopy of the wrist.