Avascular necrosis of the pisiform
ABSTRACT Avascular necrosis of the pisiform bone is a very rare condition. This paper reports a case and discusses this pathology and its diagnosis.
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ABSTRACT: Pressurized fluid has been proposed to play an important role in subchondral bone cyst development. However, the exact mechanism remains speculative. We used an established computational mechanoregulated bone adaptation model to investigate two hypotheses: 1) pressurized fluid causes cyst growth through altered bone tissue loading conditions, 2) pressurized fluid causes cyst growth through osteocyte death. In a 2D finite element model of bone microarchitecture, a marrow cavity was filled with fluid to resemble a cyst. Subsequently, the fluid was pressurized, or osteocyte death was simulated, or both. Rather than increasing the load, which was the prevailing hypothesis, pressurized fluid decreased the load on the surrounding bone, thereby leading to net bone resorption and growth of the cavity. In this scenario an irregularly shaped cavity developed which became rounded and obtained a rim of sclerotic bone after removal of the pressurized fluid. This indicates that cyst development may occur in a step-wise manner. In the simulations of osteocyte death, cavity growth also occurred, and the cavity immediately obtained a rounded shape and a sclerotic rim. Combining both mechanisms increased the growth rate of the cavity. In conclusion, both stress-shielding by pressurized fluid, and osteocyte death may cause cyst growth. In vivo observations of pressurized cyst fluid, dead osteocytes, and different appearances of cysts similar to our simulation results support the idea that both mechanisms can simultaneously play a role in the development and growth of subchondral bone cysts.Bone 06/2011; 49(4):762-8. DOI:10.1016/j.bone.2011.06.028 · 4.46 Impact Factor
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ABSTRACT: Case Description-A 6-year-old neutered female mixed-breed dog was evaluated because of a 6-week history of left forelimb lameness that varied in severity. Clinical Findings-Radiography revealed expansile and lytic changes of the left accessory carpal bone (ACB). Results of histologic evaluation of ACB core biopsy specimens indicated areas of bone necrosis. The entire left ACB was excised and submitted for histologic evaluation; results confirmed a diagnosis of idiopathic ischemic necrosis. Treatment and Outcome-Left pancarpal arthrodesis was performed to treat carpal hyperextension and persistent lameness. The dog had an excellent functional outcome with no other problems related to the carpus until its death 4 years later, further decreasing suspicion that the problem was attributable to an undetected neoplasm or bacterial or fungal osteomyelitis. Clinical Relevance-The radiographic and histologic findings for the dog of this report were similar to previously reported findings for dogs with ischemic femoral head necrosis and humans with ischemic carpal (pisiform or lunate bone) necrosis. The etiology of the ischemic ACB necrosis in this dog was not determined. To the authors' knowledge, this is the first report of a dog with idiopathic ischemic ACB necrosis. Idiopathic ischemic necrosis should be included as a differential diagnosis for dogs with lameness and destructive and expansile ACB radiographic lesions. An excellent functional outcome may be attained by means of ACB excision and pancarpal arthrodesis.Journal of the American Veterinary Medical Association 12/2013; 243(12):1746-50. DOI:10.2460/javma.243.12.1746 · 1.67 Impact Factor
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ABSTRACT: Pisotriquetral joint disorders are often under-recognized in routine clinical practice. They nevertheless represent a significant cause of ulnar side wrist pain. The aim of this article is to present the main disorders of this joint and discuss the different imaging modalities that can be useful for its assessment.Skeletal Radiology 04/2014; 43(6). DOI:10.1007/s00256-014-1848-z · 1.74 Impact Factor