Clinical diagnosis
Case 165
【Progress】
He accepted medical service of outfit brace. Because his renal function worsened, he was transported to other hospital where he was scheduled to take renal dialysis.
【Discussion】
The lunate is one of the carpal bones in the hand. It has articulations with the surrounding carpal bones and radius but not with ulna. There are articulations; radius proximally, capitate and hamate distally, triangular medially and scaphoid laterally (1, 2). There is a smooth curve between radius end and scaphoid and between radius end and lunate. The part of the lunate curve protrudes to the side of ulna end. The noteworthy is that there is no articulation between lunate and ulna, but there is a disk between them (1, 2). It indicates lunate, scaphoid and radius support and work together against the load to the hand. While, the ulna margin has horizontal end with no curve to support the hand load, indicating the lunate and ulna does not always support the hand load firmly. This structure of ulna end and TFC area is not appropriate for support of hand load but is appropriate for flexibility of various hand motion.
Actually, the load force passes to radius with 80% and to ulna with 20% when the plateau of radius is the same as that of ulna (3, 4). The more elevation of ulna plateau brings the greater load force to the ulna (2.5 mm higher, 40 % load focus) which is called positive ulnar variance, while the more descent of ulnar plateau brings the less load force to the ulna (2.5 mm lower, 5 % load focus) which is called negative ulnar variance (3, 4). As a result, the more negative ulnar variance becomes the greater load focus to the lunate.
Kienbock disease which is aseptic necrosis of the lunate is found with 75% in the condition of negative ulnar variance (5, 6). It occurs in comparatively young, active male, especially manual laborers in 90% (7). It might be related to arterial blood supply. The lunate gets the blood supply from dorsal palmer artery and its branches distribution are categorized into three types: Y type, X type and I type. I type is found in 31% with the highest risk type of the three because of the least collaterals (8, 9).
The damage degree of Kienbock disease is categorized into several stages; Stage I, radiograph normal and bone edema seen on MRI; Stage II, radiograph sclerotic lunate and maintain the shape; Stage IIIa, beginning collapse of the lunate with no scaphoid rotation; Stage IIIb, collapse of the lunate with fixed scaphoid rotation: Stage IV, collapsed lunate and the degenerated intercarpal joints (5, 6).
In our case, the patient was a fifty seven-year-old male. His right wrist radiograph showed negative ulnar variance and sclerotic ulna with maintaining its original shape (Fig. 1) and MRI showed bone edema of the lunate with no scaphoid rotation, indicating Stage II. He was scheduled to get the conservative treatment first and then, endoscopic surgery after management of renal dialysis.
【Summary】
We present a fifty seven-year-old male for the painful dorsal right wrist for approximately one week especially in case of dorsal flexion. It is borne in mind that the lunate has its articulation with the surrounding bones: radius, scaphoid, capitate, hamate and triangle but not with ulna, indicating that the lunate and ulna does not work together to support the hand load firmly. Negative ulnar variance which indicate the plateau of ulna is more descendent to the plateau of radius, makes more load to the lunate. Kienbock disease implies aseptic necrosis of the lunate and is found often in case of negative ulnar variance and in case of I type branch blood supply of dorsal capital arch. Kienboch disease is categorized into Stage I to IV. In our case, radiograph showed sclerosis of the lunate with maintaining its shape, indicating to Stage II.
【References】
1.Eathorne, SW, et al. "The wrist: clinical anatomy and physical examination--an update". Primary care. 2005; 32 : 17–33.
2.Balachandran, A, et al. . "A Study of Ossification of Capitate, Hamate, Triquetral & Lunate in Forensic Age Estimation". Indian Journal of Forensic Medicine & Toxicology. 2014; 8 : 218–224
3.Bain GI, et al. The Etiology and Pathogenesis of Kienböck Disease. J Wrist Surg. 2016 Nov; 5(4): 248–254.
4.Stahl S, et al. A systematic review of the etiopathogenesis of Kienböck's disease and a critical appraisal of its recognition as an occupational disease related to hand-arm vibration. BMC Musculoskelet Disord. 2012;13(1):225.
5.Kienböck R. Concerning traumatic malacia of the lunate and its consequences: joint degeneration and compression. Fortsch Geb Roentgen. 1910;16:77–103.
6.Lee M L. The intraosseus arterial pattern of the carpal lunate bone and its relation to avascular necrosis. Acta Orthop Scand. 1963;33:43–55.
7.van Leeuwen W F, et al. What Is the Radiographic Prevalence of Incidental Kienböck Disease? Clin Orthop Relat Res. 2016;474(3):808–813.
8.Dubey PP, et al. "Study of vascular supply of lunate and consideration applied to Kienböck disease". Hand Surg. 2011; 16 (1): 9–13.
9.Gelberman R H, et al. The vascularity of the lunate bone and Kienböck's disease. J Hand Surg Am. 1980;5(3):272–278.
2019.10.9