The pisotriquetral joint: osteoarthritis and enthesopathy

Abstract

Pisotriquetral (PT) osteoarthritis (OA) and enthesopathy of the flexor carpi ulnaris (FCU) are pathologies of the hypothenar eminence which both often remain undiagnosed, but can cause ulnar wrist pain. This study determined the prevalence of these pathologies in an older donor population. Twenty wrists were obtained from 10 cadavers with an age ranging from 65 to 94 years. Radiographs were taken of all wrists with the hand in pisotriquetral view and were assessed for osteoarthritic changes of the PT joint and signs of enthesopathy of the FCU. Ten wrists were grossly dissected and the other ten wrists were sagitally sectioned at a thickness of 10 μm. The wrists were analyzed for type and grade of osteoarthritis and signs of enthesopathy. On radiology, 2 out of 20 wrists showed no signs of osteoarthritis, 5 wrists showed severe changes. One wrist showed signs of enthesopathy. On macroscopy, 9 out of 10 wrists showed osteoartritic changes; 5 of these were severely osteoarthritic. On microscopy, all wrists showed some degree of osteoarthritis of which five showed severe changes. Signs of enthesopathy were seen in seven wrists. Pisotriquetral osteoarthritis has a high prevalence in the older donor population and may therefore be a cause of ulnar sided wrist pain. It should therefore always be considered in the differential diagnosis of ulnar sided wrist pain. By performing clinical examination with these pathologies in mind, diagnosis could be a lot faster. Furthermore, based on our results, radiographs seem to be not accurate in diagnosing osteoarthritis of the PT joint and enthesopathy of the FCU.

Keywords: Enthesopathy; Flexor carpi ulnaris; Osteoarthritis; Pisiform; Pisotriquetral joint; Triquetrum; Ulnar-sided wrist pain.

Fig. 1

Anatomic dissection of the wrist (11–36) FR flexor retinaculum, UN ulnar nerve, UA ulnar artery, T triquetrum, P pisiform, FCU flexor carpi ulnaris tendon, ADM abductor digiti minimi muscle (a). After applicance of Indian ink to the PT-joint, damaged cartilage appears black, as this ink does not adhere to subchrondral bone (b)

Fig. 2

Radiograph of a wrist with OA of the PT-joint (a, 11-30 left) next to a radiograph of a wrist without OA (b) in semisupinated oblique view

Fig. 3

a Denudation and deformation of subchondral bone in 10-105 (Safranin-O stain) b Enlargement of the cartilage layer of the hamatum in the same specimen. The safranin-O stain shows only surface discontinuity of the cartilage layer, while the cartilage layer of the PT-joint is completely deformed

Fig. 4

PT-joint in a Safranin-O stain of wrist 11-36 (right). Loss of matrix staining in the cartilaginous layer of the PT-joint, without deformation of the cartilage layer or denudation of subchondral bone

Fig. 5

Overview of the enthesis and PT-joint of the Azan stain of wrist 11-30 (left)

Fig. 6

a Enthesis in the Azan stain of 11-30 b Enthesis in the Azan stain of 11-36 c Enthesis in EvG stain of 11.06 d Enthesis in EvG stain of 10-105

Fig. 7

Denudation of subchondral bone in the PT-joint of specimen 10-105 (HE) with enlargement of the PT-joint in specimen 10-105 on the right