Chronic pain in the pisiform area may be caused by tendinitis of the insertion of the flexor carpi ulnaris, bony fractures, or osteoarthrosis of the pisotriquetral joint, which some report as a frequent site of osteoarthritis slightly less common than the scaphotrapezial osteoarthrosis . Although pain and tenderness on the palmar and ulnar aspects of the wrist in the area of the pisiform bone is fairly common, refractory pisotri-quetral osteoarthritis was unusual enough for Green to be able to make a case report of simple excision of the pisiform back in 1979 . Subper-iostal excision of pisiform bone is customarily performed after unsuccessful initial nonoperative treatment, and although the postoperative results seem to be rather good, Beckers and Koebke  have recently reported on some functional limitations resulting from pisiform excision.
Osteoarthritis of the pisotriquetral joint is most often caused by acute and chronic trauma and instability. The symptoms of osteoarthritis of the pisotriquetral joint are pain over the pisiform, with pressure and grinding of the joint. There may be ulnar nerve symptoms, and attrition or rupture of the flexor profundus tendon to the little finger. Based on the history, physical examination, and radiographic findings, osteoarthritis of the piso-triquetral joint must be differentiated from extensor carpi ulnaris tendinitis, TFCC disorders, lunotriquetral disorders, and flexor carpi ulnaris tendinitis. The best radiographic view to evaluate the pisotriquetral joint is the supinated oblique view (Fig. 7). This view is obtained by having the patient position both hands palm up on the radiographic plate, as though he were holding a large bowl.
Conservative treatment of pisotriquetral arthritis consists of local injections of steroid into the pisotriquetral joint along with nonsteroidal anti-inflammatory drugs (NSAIDs) and protective splinting. When conservative therapy fails, consideration should be given to pisiform excision.
Review of the literature on pisotriquetral arthritis reveals several small case series that report good results with pisiform excision. Gomez and colleagues  retrospectively reviewed and reported on 21 patients with a mean age of 42 who were treated with excision of the pisiform for a dysfunction of the pisotriquetral joint. The diagnoses included degenerative arthritis of the pi-sotriquetral joint (15 patients), degenerative arthritis associated with a ganglion (3 patients), and calcifications caused by flexor carpi ulnaris tendinopathy (3 patients). All patients had pain secondary to direct pressure on the pisiform. Side-to-side passive motion of the pisiform occasionally led to pain and crepitus. Degenerative arthritis and calcifications in the pisotriquetral joint were confirmed by a wrist radiograph. In 5 patients, local injection with anesthetic temporarily resolved the symptoms. At an average of 30 months follow-up, excision of the pisiform was reported as giving excellent pain relief with no functional losses.
A recent study by Gaston and coworkers  focused on pisotriquetral arthritis after midcarpal fusion. Their study was a retrospective review of nine patients requiring pisiform excision after wrist or inter-carpal arthrodesis. Six patients underwent four-corner fusions and three underwent wrist fusion. On average, patients presented with ulnar-sided wrist pain at 15 months after surgery. After other causes of pain were ruled out, all nine patients underwent pisiform excision with resolution of symptoms. In the second part of the study, a cadaver model was used to analyze the kinematics and pressure of the pisotriquetral joint for various wrist intercarpal fusion positions. The cadaveric study revealed that maximum pisotri-quetral pressures occurred at full dorsiflexion and progressively decreased with flexion. Gaston and colleagues concluded that the pisotriquetral joint should be assessed before midcarpal fusion or total wrist fusion, and highlighted performing the fusion in the appropriate amount of extension .
Despite the excellent results reported in these clinical studies, Beckers and Koebke  have reported on potential instability after pisiform excision. In their anatomic study of 112 pisotriquetral joints, mechanical tests were performed to investigate the distribution of forces within the pisiform and the pisotriquetral joint. The study authors found that the pisiform contributes to the stability
Fig. 7. Supinated oblique view of 49-year-old patient with quetral arthritis. PA views of wrists appeared normal.
of the ulnar column by supporting the triquetrum in extension and as a fulcrum for transferring forearm muscle forces to the wrist. When the pisiform was excised, this resulted in what they termed "microinstability" in their cadaver model . Whether this microinstability will translate into clinical symptoms remains to be determined.
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