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Treatment of ununited fracture of the hook of hamate by low-intensity pulsed ultrasound: A case report
Treatment of Ununited Fracture of the Hook of Hamate by Low-Intensity Pulsed Ultrasound: A Case Report Hiroyuki Fujioka, MD, Masaya Tsunoda, MD, Mitsuaki Noda, MD, Nobuzo Matsui, MD, Kosaku Mizuno, MD, Kobe, Japan A patient presented 4 months after sustaining a fracture of the hook of hamate. X-rays and computed tomography scanning of the carpal tunnel confirmed the presence of an ununited fracture. Low-intensity ultrasound was applied to the fracture site. After 4.5 months of exposure to ultrasound, union was confirmed by both x-rays and computed tomography scanning of the carpal tunnel. (J Hand Surg 2000;25A:77–79. Copyright © 2000 by the American Society for Surgery of the Hand.) Key words: Fracture, hook of hamate, ultrasound, nonunion.
Fractures of the hook of hamate have been reported in golf, tennis, baseball, and motor vehicle accidents.1–3 Because of the poor blood supply of the hamulus and the mechanical forces of the flexor tendons in the carpal tunnel, which thereby displace hamulus fractures,4,5 these fractures progress to nonunion if left untreated. Excision of the hamate hook has been reported to be useful.1–3 Even though patient satisfaction is high after excision, many patients complain of mild residual symptoms, such as painful or weak grip, altered sensibility, or tenderness of the surgical scar.3 We successfully used noninvasive low-intensity ultrasound to treat an ununited fracture of the hook of hamate.
From the Department of Orthopaedic Surgery, Kobe University School of Medicine, Kobe, Japan. Received for publication March 22, 1999; accepted in revised form July 21, 1999. 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: Hiroyuki Fujioka, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Japan 650-0017. Copyright © 2000 by the American Society for Surgery of the Hand 0363-5023/00/25A01-0002$3.00/0
Case Report An 18-year-old woman fell over her motorcycle while gripping the handlebar. She experienced pain in the hypothenar eminence of the left hand but did not seek treatment until 4 months after the injury. Physical examination revealed tenderness over the tip of the hook of hamate. Grip strength in the affected left hand was 18 kgf; it was 30 kgf in the unaffected hand. The range of motion of the fingers and the wrist and sensibility were normal. Radiography and computed tomography (CT) were performed. A fracture at the base of the hook of hamate was detected on the carpal tunnel view of the radiographs; CT scanning confirmed the presence of a fracture (Fig. 1). The patient was treated by noninvasive low-intensity ultrasound without a cast. The ultrasound device consisted of 3 components: a plastic retaining and alignment fixture, a battery-operated treatment head module that supplied the ultrasound signal to the skin at the site of the fracture, and a main operating unit (Sonic Accelerated Fracture Healing System; Exogen, Piscataway, NJ). The device was operated by 100-volt alternating current and the ultrasound signal consisted of a 200-s burst sine wave of 1.5 MHz The Journal of Hand Surgery 77
78 Fujioka et al / Ununited Fracture of the Hamate Hook
radius and tibia.6,7 These findings suggest that lowintensity ultrasound accelerates the normal fracture repair process. In animal investigations, exposure of a rat fracture model to low-intensity ultrasound increases strength of the fracture callus and aggrecan gene expression.8,9 In addition, because prostaglandin E2, which is a potent inflammation mediator, is involved in bone remodelling and stimulates proliferation of osteoblastic cells, an increase in the production of prostaglandin E2 in osteoblasts by ultrasound exposure may play an important role in the acceleration of fracture repair.10 –12 In this case, the hook of hamate was fractured by the butt end of a handlebar during a motorcycle accident. A fracture was observed on carpal tunnel x-rays and CT scans 4 months after the injury. Although it is difficult to state whether this case represented a nonunion, there was clearly a delay in union. We treated the fracture with noninvasive low-intensity ultrasound. The fracture had united by 4.5
Figure 1. Radiograph (A) and CT scan (B) 4 months after injury. The carpal tunnel x-ray shows a fracture at the base of the hook of hamate; the CT scan confirms the fracture (arrows).
repeating at 1.0 kHz. The intensity was 30 mW/cm2 spatial average and temporal average. The fracture site of the hamate in the palm was exposed to ultrasound for 20 minutes every day for 4.5 months. At the end of the treatment period there was no tenderness over the hook of hamate. The grip strength in the affected left hand was 29 kgf, almost the same as in the unaffected hand. Union of the fracture site was confirmed on the carpal tunnel radiographs and on all of the CT scans (Fig. 2). The patients was asymptomatic 6 months after the end of the ultrasound treatment.
Discussion Low-intensity ultrasound has been reported to be useful in promoting fracture healing in both clinical and basic studies.6 –10 In prospective, randomized, double-blind clinical studies, low-intensity ultrasound accelerates healing of fractures of the distal
Figure 2. Carpal tunnel radiograph (A) and CT scan (B) after 4.5 months of treatment with low-intensity pulsed ultrasound showing that the fracture at the base of the hook of hamate had united.
The Journal of Hand Surgery / Vol. 25A No. 1 January 2000 79
months of exposure to ultrasound. Based on the results of this case low-intensity pulsed ultrasound may be useful in the treatment of ununited fractures of the hook of hamate.
8.
References 1. Stark HH, Jobe FW, Boyes JH, Ashworth CR. Fracture of the hook of the hamate in athletes. J Bone Joint Surg 1977;59A:575–582. 2. Carter PR, Eaton RG, Littler JW. Ununited fracture of the hook of the hamate. J Bone Joint Surg 1977;59A:583–588. 3. Bishop AT, Beckenbaugh RD. Fracture of the hamate hook. J Hand Surg 1988;13A:135–139. 4. Panagis JS, Gelberman RH, Taleisnik J, Baumgaertner M. The arterial anatomy of the human carpus. Part II: the intraosseous vascularity. J Hand Surg 1983;8:375–382. 5. Watson HK, Rogers WD. Nonunion of the hook of the hamate: an argument for bone grafting the nonunion. J Hand Surg 1989;14A:486 – 490. 6. Heckman JD, Ryaby JP, McCabe J, Frey JJ, Kilcoyne RF. Acceleration of tibial fracture-healing by non-invasive, low-intensity pulsed ultrasound. J Bone Joint Surg 1994; 76A:26 –34. 7. Kristiansen TK, Ryaby JP, McCabe J, Frey JJ, Roe LR.
9.
10.
11.
12.
Accelerated healing of distal radial fractures with the use of specific, low-intensity ultrasound: a multicenter, prospective, randomized, double-blind, placebo-controlled study. J Bone Joint Surg 1997;79A:961–973. Wang S-J, Lewallen DG, Bolander ME, Chao EYS, Ilstrup DM, Greenleaf JF. Low intensity ultrasound treatment increases strength in a rat femoral fracture model. J Orthop Res 1994;12:40 – 47. Yang K-H, Parvizi J, Wang S-J, et al. Exposure to lowintensity ultrasound increases aggrecan gene expression in a rat femur fracture model. J Orthop Res 1996;14:802– 809. Kokubu T, Matsui N, Fujioka H, Tsunoda M, Mizuno K. Low intensity pulsed ultrasound exposure increases prostaglandin E2 production via the induction of cyclooxygenase-2 mRNA in mouse osteoblasts. Biochem Biophys Res Commun 1999;256:284 –287. Hakeda Y, Yoshino T, Nakatani Y, Kurihara M, Maeda N, Kumegawa M. Prostagrandin E2 stimulates DNA synthesis by a cyclic AMP-independent pathway in osteoblastic clone MC3T3-E1 cells. J Cell Physiol 1986;128:155–161. Raisz LG, Dietrich JW, Simmons HA, Seyberth HW, Hubbard W, Oates JA. Effect of prostaglandin endoperoxides and metabolites on bone resorption in vitro. Nature 1977; 267:532–534.
Fractures of the hook of hamate have been reported in golf, tennis, baseball, and motor vehicle accidents.1–3 Because of the poor blood supply of the hamulus and the mechanical forces of the flexor tendons in the carpal tunnel, which thereby displace hamulus fractures,4,5 these fractures progress to nonunion if left untreated. Excision of the hamate hook has been reported to be useful.1–3 Even though patient satisfaction is high after excision, many patients complain of mild residual symptoms, such as painful or weak grip, altered sensibility, or tenderness of the surgical scar.3 We successfully used noninvasive low-intensity ultrasound to treat an ununited fracture of the hook of hamate.
From the Department of Orthopaedic Surgery, Kobe University School of Medicine, Kobe, Japan. Received for publication March 22, 1999; accepted in revised form July 21, 1999. 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: Hiroyuki Fujioka, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Japan 650-0017. Copyright © 2000 by the American Society for Surgery of the Hand 0363-5023/00/25A01-0002$3.00/0
Case Report An 18-year-old woman fell over her motorcycle while gripping the handlebar. She experienced pain in the hypothenar eminence of the left hand but did not seek treatment until 4 months after the injury. Physical examination revealed tenderness over the tip of the hook of hamate. Grip strength in the affected left hand was 18 kgf; it was 30 kgf in the unaffected hand. The range of motion of the fingers and the wrist and sensibility were normal. Radiography and computed tomography (CT) were performed. A fracture at the base of the hook of hamate was detected on the carpal tunnel view of the radiographs; CT scanning confirmed the presence of a fracture (Fig. 1). The patient was treated by noninvasive low-intensity ultrasound without a cast. The ultrasound device consisted of 3 components: a plastic retaining and alignment fixture, a battery-operated treatment head module that supplied the ultrasound signal to the skin at the site of the fracture, and a main operating unit (Sonic Accelerated Fracture Healing System; Exogen, Piscataway, NJ). The device was operated by 100-volt alternating current and the ultrasound signal consisted of a 200-s burst sine wave of 1.5 MHz The Journal of Hand Surgery 77
78 Fujioka et al / Ununited Fracture of the Hamate Hook
radius and tibia.6,7 These findings suggest that lowintensity ultrasound accelerates the normal fracture repair process. In animal investigations, exposure of a rat fracture model to low-intensity ultrasound increases strength of the fracture callus and aggrecan gene expression.8,9 In addition, because prostaglandin E2, which is a potent inflammation mediator, is involved in bone remodelling and stimulates proliferation of osteoblastic cells, an increase in the production of prostaglandin E2 in osteoblasts by ultrasound exposure may play an important role in the acceleration of fracture repair.10 –12 In this case, the hook of hamate was fractured by the butt end of a handlebar during a motorcycle accident. A fracture was observed on carpal tunnel x-rays and CT scans 4 months after the injury. Although it is difficult to state whether this case represented a nonunion, there was clearly a delay in union. We treated the fracture with noninvasive low-intensity ultrasound. The fracture had united by 4.5
Figure 1. Radiograph (A) and CT scan (B) 4 months after injury. The carpal tunnel x-ray shows a fracture at the base of the hook of hamate; the CT scan confirms the fracture (arrows).
repeating at 1.0 kHz. The intensity was 30 mW/cm2 spatial average and temporal average. The fracture site of the hamate in the palm was exposed to ultrasound for 20 minutes every day for 4.5 months. At the end of the treatment period there was no tenderness over the hook of hamate. The grip strength in the affected left hand was 29 kgf, almost the same as in the unaffected hand. Union of the fracture site was confirmed on the carpal tunnel radiographs and on all of the CT scans (Fig. 2). The patients was asymptomatic 6 months after the end of the ultrasound treatment.
Discussion Low-intensity ultrasound has been reported to be useful in promoting fracture healing in both clinical and basic studies.6 –10 In prospective, randomized, double-blind clinical studies, low-intensity ultrasound accelerates healing of fractures of the distal
Figure 2. Carpal tunnel radiograph (A) and CT scan (B) after 4.5 months of treatment with low-intensity pulsed ultrasound showing that the fracture at the base of the hook of hamate had united.
The Journal of Hand Surgery / Vol. 25A No. 1 January 2000 79
months of exposure to ultrasound. Based on the results of this case low-intensity pulsed ultrasound may be useful in the treatment of ununited fractures of the hook of hamate.
8.
References 1. Stark HH, Jobe FW, Boyes JH, Ashworth CR. Fracture of the hook of the hamate in athletes. J Bone Joint Surg 1977;59A:575–582. 2. Carter PR, Eaton RG, Littler JW. Ununited fracture of the hook of the hamate. J Bone Joint Surg 1977;59A:583–588. 3. Bishop AT, Beckenbaugh RD. Fracture of the hamate hook. J Hand Surg 1988;13A:135–139. 4. Panagis JS, Gelberman RH, Taleisnik J, Baumgaertner M. The arterial anatomy of the human carpus. Part II: the intraosseous vascularity. J Hand Surg 1983;8:375–382. 5. Watson HK, Rogers WD. Nonunion of the hook of the hamate: an argument for bone grafting the nonunion. J Hand Surg 1989;14A:486 – 490. 6. Heckman JD, Ryaby JP, McCabe J, Frey JJ, Kilcoyne RF. Acceleration of tibial fracture-healing by non-invasive, low-intensity pulsed ultrasound. J Bone Joint Surg 1994; 76A:26 –34. 7. Kristiansen TK, Ryaby JP, McCabe J, Frey JJ, Roe LR.
9.
10.
11.
12.
Accelerated healing of distal radial fractures with the use of specific, low-intensity ultrasound: a multicenter, prospective, randomized, double-blind, placebo-controlled study. J Bone Joint Surg 1997;79A:961–973. Wang S-J, Lewallen DG, Bolander ME, Chao EYS, Ilstrup DM, Greenleaf JF. Low intensity ultrasound treatment increases strength in a rat femoral fracture model. J Orthop Res 1994;12:40 – 47. Yang K-H, Parvizi J, Wang S-J, et al. Exposure to lowintensity ultrasound increases aggrecan gene expression in a rat femur fracture model. J Orthop Res 1996;14:802– 809. Kokubu T, Matsui N, Fujioka H, Tsunoda M, Mizuno K. Low intensity pulsed ultrasound exposure increases prostaglandin E2 production via the induction of cyclooxygenase-2 mRNA in mouse osteoblasts. Biochem Biophys Res Commun 1999;256:284 –287. Hakeda Y, Yoshino T, Nakatani Y, Kurihara M, Maeda N, Kumegawa M. Prostagrandin E2 stimulates DNA synthesis by a cyclic AMP-independent pathway in osteoblastic clone MC3T3-E1 cells. J Cell Physiol 1986;128:155–161. Raisz LG, Dietrich JW, Simmons HA, Seyberth HW, Hubbard W, Oates JA. Effect of prostaglandin endoperoxides and metabolites on bone resorption in vitro. Nature 1977; 267:532–534.