Avascular necrosis of the hamate: A case report with reference to the hamate blood supply Avascular necrosis of the hamate bone has not previously been reported. In this case the proximal fragment of the fractured hamate underwent avascular necrosis and prolonged healing. In an attempt to explain this sequela, angiography of the cadaver carpus followed by dissection of intact wrists and a study of enzyme-cleaned hamates showed that their wedge-shaped proximal segments were mostly enveloped by a distaJ extension of the midcarpal joint cavity and thus totally dependent on intraosseous nutrition. Consequently, the segment is at risk when a fracture line transects the body proximal to the base of the wedge. Clinically, this condition resulted in persistent discomfort and limitations of motion. A postinjury bone scan of the wrist indicated avascular changes in the proximal third of the hamate, and a delayed union was followed by later revascularization and a more normal scan image. (J HAND SURG 1992;17A:I086-90.)
Robert E. Van Demark, MD, Sioux Falls, S.D., and Wesley W. Parke, PhD, Vermillion, S.D. From the Department of Orthopaedic Surgery, University of South Dakota School of Medicine, Sioux Falls, and the Department of Anatomy, University of South Dakota School of Medicine, Vermillion, S.D. Received for publication Oct. 7, 1991; accepted in revised form Jan. 9, [992.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Wesley W. Parke, PhD, Department of Anatomy, University of South Dakota School of Medicine, Vermillion. SD 57069.
3/1/36900
B Fig.!. A, X-ray film of injured hand. Arrows indicate fracture lines through distal scaphoid, proximal capitate, and base of wedge of hamate. B, Bone scan showing avascular necrosis.
1086
THE JOURNAL OF HAND SURGERY
Vol. l7A, No.6 November 1992
Avascular necrosis of hamate
1087
Fracture of the body of the hamate bone is uncommon. I The case report that follows is the twentieth clinical description recorded .P?
Case report A 45-year-old man sustained a shearing injury to the right wrist when his hand was caught under a machine while he was making plastic bottles. Physical examination showed a 5.3 cm laceration of the dorsal carpal area and a corresponding palmar carpal laceration 5.5 cm in length. The carpal area was swollen, but sensation and circulation in the digits were satisfactory. Although the lacerations proved to be superficial, the initial x-ray film showed a fracture through the midportion of the right hamate, a nondisplaced fracture of the distal aspect of the right scaphoid, and a possible nondisplaced hairline fracture through the midportion of the capitate (Fig . I, A). Prompt wound cleansing, debridement, and closure were followed by the application of a palmar plaster splint for immobilization . The wounds healed primarily. Repeat x-ray films confirmed the fracture of the capitate. A bone scan was taken to determine the vascular status of the proximal fragment . This was normal, but, surprisingly, that of the proximal hamate was abnormal (Fig. 1, B). The injury was treated with a cast until 3 months after the injury, when x-ray films of the scaphoid and capitate showed healing. The patient was given a wrist support to protect the hamate . Subsequent x-ray films (Fig . 2) showed avascular necrosis and delayed healing of the proximal portion of the hamate and osteopenia of surrounding bones. One year after the injury, the patient's wrist showed flexion to 45 degrees, extension to 53 degrees, ulnar deviation of 20 degrees, and radial deviation of 14 degrees. His grip strength, as determined with the Jamar dynamometer 011 the third notch, was 110 pounds on the injured right hand and 125 pounds on the left. Although it was explained that a carpal fusion (hamate to triquetrum) might lessen residual pain at the expense of some range of motion, the patient declined surgery because he was able to return to his previous employment.
Anatomic investigation The internal vascularity of the hamate has been well documented in the reports of Grettve,? Barber," and Panagis et al. I All of these investigations used vascular injection and clearing techniques , and all were in agreement that the hamate body on its palmar and dorsal surfaces receives several arteries, which show various degrees of intraosseous anastomoses . Although Grettve and Panagis et al. described and photographically illustrated the hamate nutrient arteries as penetrating the distal segment exclusively, only Barber specifically commented that the proximal segment was entirely dependent on intraosseous vascularity. He used the term
Fig, 2. X-ray film. The arrow indicates the persistence of the medial portion of the hamate fracture line.
wedge to designate this part of the hamate. None of these investigators were aware that a fractured wedge of the hamate could be at vascular risk or knew why it received no external vessels. Since all three studies were based on observations of harnates separated from the other carpal bones by chemical maceration, we employed x-ray films for more precise studies of the vascularity of the hamate.
Materials and methods Six forearms (four right, two left) were removed from six cadavers and injected via the ulnar artery with a low-viscosity, finely divided aqueous suspension of barium sulfate (Micropaque, Nicholas Laboratories, Ltd .• Slough, England). These were then frozen and sectioned on a bandsaw through a parasagittal plane just medial to the long axis of the hand. The cuts medial to the center of the capitate, and the thin medial section of the capitate that was removed showed the isolated dorsal and ventral blood supplies of the hamate bone (Fig . 3).
The Journal of 1088
Vall Demark alit! Parke
HAND SURGERY
Fig. 3. X-ray film showing vascularity of ulnar section of 72-year-old male forearm. Vessels were injected with a barium sulfate suspension. The preparation was sectioned parasagittal to the ulnar side of the hand axis. A section of the radius (A) is superimposed on the ulna, and a section of the lunate (B) is superimposed on the triquetrum. The pisiform (C), hamate (D), and proximal ends of the ring and small finger metacarpals (E) are shown. The palmar blood supply to the hamate is shown to be derived from the deep palmar branch (3) of the ulnar artery (1) and the ulnar anterior carpal branch (2). The dorsal carpal artery (4), here derived from the interosseous artery of the forearm, forms an intraosseous anastomotic arcade (5) with a branch of the anterior carpal artery. This arcade is the source of the exclusively intraosseous blood supply of the intra-articular hamate wedge that is indicated by the asterisk.
1
PROXI tAL
3 Fig. 4. Schema derived from information provided by present study combined with previously published data.?" The contributions of the ulnar (1), anterior carpal (2), and dorsal carpal (3) arteries are shown. Note that the proximal segment of the hamate, vascularly isolated by the intra-articular position of the articular and the palmar and dorsal surfaces of the wedge, is solely dependent on intraosseous nutrition. The critical plane, proximal to which fractures may cause avascular necrosis, is indicated by the dotted line.
For a study of the blood supply to the hamate wedge, the carpal bones of the left wrists of I a cadavers were cleaned in a proteolytic enzyme solution (papain) and examined for nutrient foramina under a I a-power dissecting microscope. Five of the right wrists of these same cadavers were then dissected for examination of the joint capsule and ligamentous relationships of the hamate in the intact carpus. Results
The vascular injection/radiographic studies of the hamate blood supply confirmed descriptions in previous reports, I. 7.8 but those showed only that the distal portion of the hamate is externally vascularized. Fig. 3 shows that the palmar hamate surface receives blood vessels from the palmar carpal branch and deep palmar branches of the ulnar artery and that the dorsal surface receives nutrient vessels from a dorsal carpal artery, which is usually a branch of the ulnar artery but may, as illustrated here, arise from a perforating branch of the anterior interosseous artery of the forearm. Also, in five of the six specimens injected, the conspicuous intraosseous anastomosis between the dorsal and palmar
Vol. 17A, No.6 November 1992
Avascular necro sis of hamate
1089
Fig. 5. Composite photograph showing palmar (A) and dorsal (8) surfaces of an enzymatically cleaned left hamate bone of a 62-year-old man. The presence of nutrient foramina in only the distal body segment is apparent. The shaded overlays indicate the positions and relative thickness of the palmar and dorsal distal attachments of the ligaments of the midcarpal joint capsule as determined from five dissections. Note that the dorsal and palmar wedge surfaces proximal to these attachments are intra-articular, as the line of synovial membrane reflection is coincident with the proximal margins of the ligament attachments. Since external vascularization of the hamate body is possible only distal to these lines of attachment, the intraosseous plane that forms the base of the wedge provides a reliable indicator of the critical plane of proximal segment fracture.
arteries was well demonstrated (Fig. 3, 5). As this anastomotic arcade courses just distal to the basal plane of the wedge, our specimens reaffirmed the observations of Barber that this arcade was the main source of the proximally directed intraosseous vessels that are the exclusive supply of this segment. From these radiologic studies and the illustrations provided by Barber" and Grettve,? a three-dimensional schema of the hamate blood supply (Fig. 4) could be derived. The low-power microscopic examination of the enzymatically cleaned hamates confirmed the previously reported observations that the number of vessels entering the hamate body was quite variable-two to three on the dorsal surface and three to fi ve on the palmar surface. We also observed that only two or three vessels had significantly extensive intraosseous distributions. This series of bones also confirmed that there were no nutrient foramina of precapillary size to be found on the dorsal or palmar surfaces of the wedge. After reflecting the palmar and dorsal radiocarpal ligaments, a transverse incision of the midcarpal joint capsule exposed the midcarpal joint cavity. Elevation and reflection of the distal attachments of the capsular
ligaments revealed that a distal extension of the midcarpal joint cavity enveloped the greater part of the wedge so that three fourths of its palmar surface and all of its dorsal surface was intra-articular and covered with synovial membrane. Thus the hamate wedge (Fig. 5) is virtually an intra-articular structure and, as such, like the head of the capitate and the proximal pole of the scaphoid, is at risk should its intraosseous vascularity be interrupted by fracture through its base. Discussion The relative rarity of fractures of the body of the hamate may partially account for the fact that the risk of avascular necrosis in the fractured wedge segment had not been recognized. Evidently, carpal kinetics are such that an isolated fracture of the hamate is an extremely rare event. The cited reports indicate that, as in the case described here, it is almost always associated with a trauma involving other carpal bones. Thus, when one is confronted with multiple carpal fractures that include the hamate, an x-ray film of the position of the fracture line relative to the base of the wedge could, with the information presented here, warn the observer
The Journal of HAND SURGERY
Van Demark and Parke
of a potential avascular necrosis. An oblique fracture of the hamate body, as described and illustrated by Ogunro," that transects this plane would not likely result in avascularity, since both fragments would still have access to an external arterial supply. Also. transverse fractures distal to this critical plane would likely leave both segments vascularized. However, should a transverse fracture line occur at the level of or proximal to this plane, avascular necrosis of the proximal segment is a definite possibility, particularly if there is displacement. REFERENCES 1. Panagis IS, Gelbennan RH, Taleisnik J, Baumgartner M. The arterial anatomy of the human carpus. Part II. The intraosseous vascularity. 1 HAND SURG 1983;8:375-82.
2. Baird DB, Friedenberg ZB. Delayed ulnar nerve palsy following fracture of the hamate. J Bone Joint Surg 1968;50A:570-2. 3. Bowen TL. Injuries of the hamate bone. Hand 1973;5: 235-8. 4. Howard FM. Ulnar nerve palsies in wrist fractures. 1 Bone Joint Surg 1961;43A:1l97-201. 5. Milch H. Fracture of the hamate bone. J Bone loint Surg 1934;16:459-62. 6. Ogunro O. Fracture of the body of the hamate bone. 1 HAND SURG 1983;8:353-5. 7. Grettve S. Arterial anatomy of the carpal bone. Acta Anat 1955;23:331-45. 8. Barber H. The intraosseous arterial anatomy of the adult human carpus. Orthopaedics-Oxford 1972;5:1-20.
Avascular necrosis of the capitate: A case report Anthony S. Lapinsky, MD, and Gregory R. Mack, MD, San Diego, Calif.
Avascular necrosis (AVN) of the capitate is rarely idiopathic. Most cases involve direct or indirect traurna.!" To our knowledge, the case that follows is the third reported case that may be idiopathic." 4 AVN within the carpus correlates most strongly with vascularity. A bone or bone fragment supplied by a
From the Departments of Orthopedics and Clinical Investigation, Naval Hospital, San Diego, Calif. The Chief, Navy Bureau of Medicine and Surgery, Washington, DC, Clinical Investigation Program sponsored this case report No. 8416-1968-284. The views expressed in this article arc those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States Government. Received for publication Oct. 10, 1991; accepted in revised form May 7, 1992. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Capt. G. R. Mack, MC, USN, clo Clinicallnvestigation Department, Naval Hospital, San Diego, CA 92134-5000.
3/1/39663
1090
THE JOURNAL OF HAND SURGERY
single end artery may be more at risk of AVN due to trauma or embolism. Single vessel patterns have been identified in the proximal scaphoid, 20% of the lunates, and the dome of the capitate. 10 AVN after vascular interruption by fracture has been most commonly cited for the proximal pole of the scaphoid. 10. II Repetitive minor tauma has been postulated as a cause of Kienbock's disease, and compression fracture before a change in radiographic density has been demonstrated in some cases. 12 Like the scaphoid, the proximal pole of the capitate may develop AVN after fracture. 13 The cause of whole bone AVN of the capitate has not been elucidated. Case report A 20-year-old right-handed woman with an II-month history of right wrist pain and swelling was referred after splinting and nonsteroidal anti-inflammatory medication had failed to relieve her pain. X-ray films taken at the onset of symptoms and I month before referral were normal, Her pain then increased, was worse at night, and was aggravated by any use of the wrist. Examination revealed dorsal swelling over the right midcarpal joint. Wrist motion (right/left, in degrees) was as follows: extension, 35/68; palmar flexion, 45/75; radial deviation, 15/18; and ulnar deviation, 33/36. Average
Robert E. Van Demark, MD, Sioux Falls, S.D., and Wesley W. Parke, PhD, Vermillion, S.D. From the Department of Orthopaedic Surgery, University of South Dakota School of Medicine, Sioux Falls, and the Department of Anatomy, University of South Dakota School of Medicine, Vermillion, S.D. Received for publication Oct. 7, 1991; accepted in revised form Jan. 9, [992.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Wesley W. Parke, PhD, Department of Anatomy, University of South Dakota School of Medicine, Vermillion. SD 57069.
3/1/36900
B Fig.!. A, X-ray film of injured hand. Arrows indicate fracture lines through distal scaphoid, proximal capitate, and base of wedge of hamate. B, Bone scan showing avascular necrosis.
1086
THE JOURNAL OF HAND SURGERY
Vol. l7A, No.6 November 1992
Avascular necrosis of hamate
1087
Fracture of the body of the hamate bone is uncommon. I The case report that follows is the twentieth clinical description recorded .P?
Case report A 45-year-old man sustained a shearing injury to the right wrist when his hand was caught under a machine while he was making plastic bottles. Physical examination showed a 5.3 cm laceration of the dorsal carpal area and a corresponding palmar carpal laceration 5.5 cm in length. The carpal area was swollen, but sensation and circulation in the digits were satisfactory. Although the lacerations proved to be superficial, the initial x-ray film showed a fracture through the midportion of the right hamate, a nondisplaced fracture of the distal aspect of the right scaphoid, and a possible nondisplaced hairline fracture through the midportion of the capitate (Fig . I, A). Prompt wound cleansing, debridement, and closure were followed by the application of a palmar plaster splint for immobilization . The wounds healed primarily. Repeat x-ray films confirmed the fracture of the capitate. A bone scan was taken to determine the vascular status of the proximal fragment . This was normal, but, surprisingly, that of the proximal hamate was abnormal (Fig. 1, B). The injury was treated with a cast until 3 months after the injury, when x-ray films of the scaphoid and capitate showed healing. The patient was given a wrist support to protect the hamate . Subsequent x-ray films (Fig . 2) showed avascular necrosis and delayed healing of the proximal portion of the hamate and osteopenia of surrounding bones. One year after the injury, the patient's wrist showed flexion to 45 degrees, extension to 53 degrees, ulnar deviation of 20 degrees, and radial deviation of 14 degrees. His grip strength, as determined with the Jamar dynamometer 011 the third notch, was 110 pounds on the injured right hand and 125 pounds on the left. Although it was explained that a carpal fusion (hamate to triquetrum) might lessen residual pain at the expense of some range of motion, the patient declined surgery because he was able to return to his previous employment.
Anatomic investigation The internal vascularity of the hamate has been well documented in the reports of Grettve,? Barber," and Panagis et al. I All of these investigations used vascular injection and clearing techniques , and all were in agreement that the hamate body on its palmar and dorsal surfaces receives several arteries, which show various degrees of intraosseous anastomoses . Although Grettve and Panagis et al. described and photographically illustrated the hamate nutrient arteries as penetrating the distal segment exclusively, only Barber specifically commented that the proximal segment was entirely dependent on intraosseous vascularity. He used the term
Fig, 2. X-ray film. The arrow indicates the persistence of the medial portion of the hamate fracture line.
wedge to designate this part of the hamate. None of these investigators were aware that a fractured wedge of the hamate could be at vascular risk or knew why it received no external vessels. Since all three studies were based on observations of harnates separated from the other carpal bones by chemical maceration, we employed x-ray films for more precise studies of the vascularity of the hamate.
Materials and methods Six forearms (four right, two left) were removed from six cadavers and injected via the ulnar artery with a low-viscosity, finely divided aqueous suspension of barium sulfate (Micropaque, Nicholas Laboratories, Ltd .• Slough, England). These were then frozen and sectioned on a bandsaw through a parasagittal plane just medial to the long axis of the hand. The cuts medial to the center of the capitate, and the thin medial section of the capitate that was removed showed the isolated dorsal and ventral blood supplies of the hamate bone (Fig . 3).
The Journal of 1088
Vall Demark alit! Parke
HAND SURGERY
Fig. 3. X-ray film showing vascularity of ulnar section of 72-year-old male forearm. Vessels were injected with a barium sulfate suspension. The preparation was sectioned parasagittal to the ulnar side of the hand axis. A section of the radius (A) is superimposed on the ulna, and a section of the lunate (B) is superimposed on the triquetrum. The pisiform (C), hamate (D), and proximal ends of the ring and small finger metacarpals (E) are shown. The palmar blood supply to the hamate is shown to be derived from the deep palmar branch (3) of the ulnar artery (1) and the ulnar anterior carpal branch (2). The dorsal carpal artery (4), here derived from the interosseous artery of the forearm, forms an intraosseous anastomotic arcade (5) with a branch of the anterior carpal artery. This arcade is the source of the exclusively intraosseous blood supply of the intra-articular hamate wedge that is indicated by the asterisk.
1
PROXI tAL
3 Fig. 4. Schema derived from information provided by present study combined with previously published data.?" The contributions of the ulnar (1), anterior carpal (2), and dorsal carpal (3) arteries are shown. Note that the proximal segment of the hamate, vascularly isolated by the intra-articular position of the articular and the palmar and dorsal surfaces of the wedge, is solely dependent on intraosseous nutrition. The critical plane, proximal to which fractures may cause avascular necrosis, is indicated by the dotted line.
For a study of the blood supply to the hamate wedge, the carpal bones of the left wrists of I a cadavers were cleaned in a proteolytic enzyme solution (papain) and examined for nutrient foramina under a I a-power dissecting microscope. Five of the right wrists of these same cadavers were then dissected for examination of the joint capsule and ligamentous relationships of the hamate in the intact carpus. Results
The vascular injection/radiographic studies of the hamate blood supply confirmed descriptions in previous reports, I. 7.8 but those showed only that the distal portion of the hamate is externally vascularized. Fig. 3 shows that the palmar hamate surface receives blood vessels from the palmar carpal branch and deep palmar branches of the ulnar artery and that the dorsal surface receives nutrient vessels from a dorsal carpal artery, which is usually a branch of the ulnar artery but may, as illustrated here, arise from a perforating branch of the anterior interosseous artery of the forearm. Also, in five of the six specimens injected, the conspicuous intraosseous anastomosis between the dorsal and palmar
Vol. 17A, No.6 November 1992
Avascular necro sis of hamate
1089
Fig. 5. Composite photograph showing palmar (A) and dorsal (8) surfaces of an enzymatically cleaned left hamate bone of a 62-year-old man. The presence of nutrient foramina in only the distal body segment is apparent. The shaded overlays indicate the positions and relative thickness of the palmar and dorsal distal attachments of the ligaments of the midcarpal joint capsule as determined from five dissections. Note that the dorsal and palmar wedge surfaces proximal to these attachments are intra-articular, as the line of synovial membrane reflection is coincident with the proximal margins of the ligament attachments. Since external vascularization of the hamate body is possible only distal to these lines of attachment, the intraosseous plane that forms the base of the wedge provides a reliable indicator of the critical plane of proximal segment fracture.
arteries was well demonstrated (Fig. 3, 5). As this anastomotic arcade courses just distal to the basal plane of the wedge, our specimens reaffirmed the observations of Barber that this arcade was the main source of the proximally directed intraosseous vessels that are the exclusive supply of this segment. From these radiologic studies and the illustrations provided by Barber" and Grettve,? a three-dimensional schema of the hamate blood supply (Fig. 4) could be derived. The low-power microscopic examination of the enzymatically cleaned hamates confirmed the previously reported observations that the number of vessels entering the hamate body was quite variable-two to three on the dorsal surface and three to fi ve on the palmar surface. We also observed that only two or three vessels had significantly extensive intraosseous distributions. This series of bones also confirmed that there were no nutrient foramina of precapillary size to be found on the dorsal or palmar surfaces of the wedge. After reflecting the palmar and dorsal radiocarpal ligaments, a transverse incision of the midcarpal joint capsule exposed the midcarpal joint cavity. Elevation and reflection of the distal attachments of the capsular
ligaments revealed that a distal extension of the midcarpal joint cavity enveloped the greater part of the wedge so that three fourths of its palmar surface and all of its dorsal surface was intra-articular and covered with synovial membrane. Thus the hamate wedge (Fig. 5) is virtually an intra-articular structure and, as such, like the head of the capitate and the proximal pole of the scaphoid, is at risk should its intraosseous vascularity be interrupted by fracture through its base. Discussion The relative rarity of fractures of the body of the hamate may partially account for the fact that the risk of avascular necrosis in the fractured wedge segment had not been recognized. Evidently, carpal kinetics are such that an isolated fracture of the hamate is an extremely rare event. The cited reports indicate that, as in the case described here, it is almost always associated with a trauma involving other carpal bones. Thus, when one is confronted with multiple carpal fractures that include the hamate, an x-ray film of the position of the fracture line relative to the base of the wedge could, with the information presented here, warn the observer
The Journal of HAND SURGERY
Van Demark and Parke
of a potential avascular necrosis. An oblique fracture of the hamate body, as described and illustrated by Ogunro," that transects this plane would not likely result in avascularity, since both fragments would still have access to an external arterial supply. Also. transverse fractures distal to this critical plane would likely leave both segments vascularized. However, should a transverse fracture line occur at the level of or proximal to this plane, avascular necrosis of the proximal segment is a definite possibility, particularly if there is displacement. REFERENCES 1. Panagis IS, Gelbennan RH, Taleisnik J, Baumgartner M. The arterial anatomy of the human carpus. Part II. The intraosseous vascularity. 1 HAND SURG 1983;8:375-82.
2. Baird DB, Friedenberg ZB. Delayed ulnar nerve palsy following fracture of the hamate. J Bone Joint Surg 1968;50A:570-2. 3. Bowen TL. Injuries of the hamate bone. Hand 1973;5: 235-8. 4. Howard FM. Ulnar nerve palsies in wrist fractures. 1 Bone Joint Surg 1961;43A:1l97-201. 5. Milch H. Fracture of the hamate bone. J Bone loint Surg 1934;16:459-62. 6. Ogunro O. Fracture of the body of the hamate bone. 1 HAND SURG 1983;8:353-5. 7. Grettve S. Arterial anatomy of the carpal bone. Acta Anat 1955;23:331-45. 8. Barber H. The intraosseous arterial anatomy of the adult human carpus. Orthopaedics-Oxford 1972;5:1-20.
Avascular necrosis of the capitate: A case report Anthony S. Lapinsky, MD, and Gregory R. Mack, MD, San Diego, Calif.
Avascular necrosis (AVN) of the capitate is rarely idiopathic. Most cases involve direct or indirect traurna.!" To our knowledge, the case that follows is the third reported case that may be idiopathic." 4 AVN within the carpus correlates most strongly with vascularity. A bone or bone fragment supplied by a
From the Departments of Orthopedics and Clinical Investigation, Naval Hospital, San Diego, Calif. The Chief, Navy Bureau of Medicine and Surgery, Washington, DC, Clinical Investigation Program sponsored this case report No. 8416-1968-284. The views expressed in this article arc those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States Government. Received for publication Oct. 10, 1991; accepted in revised form May 7, 1992. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Capt. G. R. Mack, MC, USN, clo Clinicallnvestigation Department, Naval Hospital, San Diego, CA 92134-5000.
3/1/39663
1090
THE JOURNAL OF HAND SURGERY
single end artery may be more at risk of AVN due to trauma or embolism. Single vessel patterns have been identified in the proximal scaphoid, 20% of the lunates, and the dome of the capitate. 10 AVN after vascular interruption by fracture has been most commonly cited for the proximal pole of the scaphoid. 10. II Repetitive minor tauma has been postulated as a cause of Kienbock's disease, and compression fracture before a change in radiographic density has been demonstrated in some cases. 12 Like the scaphoid, the proximal pole of the capitate may develop AVN after fracture. 13 The cause of whole bone AVN of the capitate has not been elucidated. Case report A 20-year-old right-handed woman with an II-month history of right wrist pain and swelling was referred after splinting and nonsteroidal anti-inflammatory medication had failed to relieve her pain. X-ray films taken at the onset of symptoms and I month before referral were normal, Her pain then increased, was worse at night, and was aggravated by any use of the wrist. Examination revealed dorsal swelling over the right midcarpal joint. Wrist motion (right/left, in degrees) was as follows: extension, 35/68; palmar flexion, 45/75; radial deviation, 15/18; and ulnar deviation, 33/36. Average
