Pisotriquetral Joint Anatomy in Magnetic Resonance Imaging, Establishing Normative Values
Sameer Massand, MD1; Weaver Kesler, MD1; Brittany Ammerman, MD2; Kenneth Taylor, MD1
1Penn State Hershey Medical Center, Hershey, PA; 2Penn State College of Medicine, Hershey, PA
Background: Despite its structural importance in the ulnar wrist, the pisotriquetral joint has remained undefined by magnetic resonance imaging (MRI) evaluation in live patients. Establishing normative values of pisotriquetral joint parameters - pisotriquetral angle, pisohamate distance, and pisotriquetral distance - in live-patient MRI studies will provide another tool for diagnosis of destabilizing injuries to the pisotriquetral joint.
Methods: All wrist MRI studies at our institution between September 2019 and October 2020 were reviewed, specifically measuring the pisotriquetral angle, pisohamate distance, and pisotriquetral distance. Two separate authors performed all measurements individually. Each of the three measurements was averaged separately to establish reference values, and inter-reviewer reliability was calculated for each measurement. Additionally, a sub-set analysis was performed comparing values in patients with a history of wrist surgery to those without. Finally, these values were compared to those in a patient with known pisometacarpal ligament tear.
Results: We identified 122 consecutive wrist MRI studies, 102 of which met criteria. Mean pisotriquetral angle was 4.73 degrees, with an intraclass correlation coefficient of 0.88 (good reliability.) Mean pisohamate distance was 4.60mm with an intraclass correlation coefficient of 0.76 (good reliability.) Mean pisotriquetral distance was 2.02mm with an intraclass correlation coefficient of 0.54 (moderate reliability.) There was no difference in any of the three values between those with history of wrist surgery and those without. A patient with known pisometacarpal tear had two out of three values above the 95% confidence interval upper bound for pisotriquetral angle (43 degrees) and pisotriquetral distance (4.0 mm).
Conclusions: We establish normative values for the pisotriquetral angle, pisohamate distance, and pisotriquetral distance as measured by MRI, and provide a case of pisometacarpal ligament injury for contrast. These values can serve as another diagnostic tool for hand surgeons when evaluating a patient with potential pisometacarpal ligament injury.
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