- Email: [email protected]
Pathological Fracture of the Proximal Tibia from an Intraosseous Gouty Tophus: A Rare Presentation of Gout
Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
Contents lists available at ScienceDirect
Journal of Orthopaedics, Trauma and Rehabilitation Journal homepages: www.e-jotr.com & www.ejotr.org
Case Report
Pathological Fracture of the Proximal Tibia from an Intraosseous Gouty Tophus: A Rare Presentation of Gout 骨內痛風石導致病理性脛骨折的案例 e 一個罕見痛風症的例子 Chan Chi Chiu Dennis*, Chui King Him Tim, Lee Kin Bong Department of Orthopaedics and Traumatology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 December 2016 Received in revised form 8 May 2017 Accepted 15 May 2017
Intraosseous gouty tophus as the cause of pathological fracture is a seldom encountered condition. Not only does the tophus lesion affect the bone, but recent literature has also demonstrated a correlation between bone health in relation to gout as a disease entity, and showed the importance of medical treatment to improve the bone quality in patients with gout. We present a rare case of a pathological fracture due to an intraosseous gouty tophus as the presentation of gout, which imposed a diagnostic challenge, and illustrates the importance of multidisciplinary management in such conditions.
Keywords: fracture fixation gout intramedullary pathological fracture tibial fractures
中 文 摘 要 骨內痛風石是病理性骨折中較為罕見的情況。最近研究文獻指出痛風與骨格健康之間存在相關性, 並顯示出藥 物治療有助改善痛風症患者的骨質量。我們提出一個骨內痛風石導致病理性骨折的案例，以說明其診斷的挑 戰性及多學科管理對此病例的重要性。
Introduction
Case Report
Intraosseous gouty tophus as the cause of pathological fracture is a seldom encountered condition. From the current literature, the majority of the reported cases of intraosseous gouty tophus related pathological fracture occurs at the patella. A literature search by Nguyen et al1 found only 13 cases of pathological fracture from gouty tophi since 1950; seven of which involved the patella bone. We present a case of an intraosseous gouty tophus pathological fracture in a less reported bone; the tibia. The presentation of the patient imposes a diagnostic challenge. The site of the fracture is at around the proximal tibia, which further imposes a technical difficulty in fracture fixation. The management of such cases should be multidisciplinary, which involves the treatment of the fracture, as well as the condition of gout. Recent literature has demonstrated a correlation between the bone health in relation to gout, and also showed the importance of medical treatment for gout in regards to the bone and its formation.
We present a case of a 41-year-old man, with a past medical history of alcohol dependence and mood disorder, who presented with a 1-week history of sudden onset left leg pain, without any history of trauma. He presented with fever, and physical examination showed erythema with tenderness over the proximal left shin. His white blood cell count was elevated to 13.1 109/L, Creactive protein elevated to 240 mg/L, and alkaline phosphatase level elevated to 181 IU/L. His serum urate level was not elevated at 0.49 mmol/L. The x-ray of the left leg showed a proximal tibia lytic lesion with cortical breakage (Figure 1). Contrast computed tomography (CT) of the left leg showed features suggestive of an aggressive bone tumour with pathological fracture and a large extraosseous soft tissue mass (Figure 2). Bone scan showed markedly increased uptake at the proximal third of the left tibia suggestive of a primary bone tumour, and lesions in the right clavicle, left eight to the 10th rib, and right sixth and seventh rib are suggestive of bone secondaries. In addition, it showed increased uptake in bilateral shoulders, elbows, wrists, knees, ankles, and mid feet, which were suggestive of polyarthritis. With such radiological findings showing a high
* Corresponding author. E-mail: [email protected].
http://dx.doi.org/10.1016/j.jotr.2017.05.002 2210-4917/Copyright © 2017, Hong Kong Orthopaedic Association and the Hong Kong College of Orthopaedic Surgeons. Published by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
50
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
Figure 1. X-ray on presentation showing osteolytic lesions over the proximal tibia, with subtle cortical breakage of the cortex.
Figure 2. CT showing an intraosseous mass extending medially and posteriorly outside the tibia bone. Associated fracture can be demonstrated in these films. CT ¼ computed tomography.
suspicion of malignancy, it was decided that the choice of the next investigation was to achieve a histological diagnosis. A biopsy was performed for confirmation of the diagnosis. Meanwhile, the patient was put on a slab for temporarily immobilization of the fracture. The fine needle aspiration was performed under ultrasound guidance, and the histological findings showed no evidence of malignancy, but instead showed gouty tophi. The biopsy was negative for culture, acid fast bacilli, and fungus. CT guided biopsy was also done, and again showed gouty tophus, with no evidence
of malignancy (Figure 3). The patient had not been aware he had gouty arthritis, and the disease was presented as a pathological fracture. After reaching the diagnosis of gouty tophus with pathological fracture at the proximal third of the tibia shaft, we planned to offer operative fixation of the fracture. Plating and intramedullary nailing for fixation of extra-articular proximal tibia fracture have shown comparable results in terms of infection rate, range of motion, mal-union, and nonunion.2 However, in our case, plate
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
51
Figure 3. Clinical photograph showing the planned biopsy site and CT guided image of the biopsy track. CT ¼ computed tomography.
fixation was considered to be less stable for this proximal fracture with a large lytic lesion around. In addition, given the large extraosseous component of the lesion, plate was considered less favourable. The operation of intramedullary nailing was therefore
chosen (Figure 4). A T2 tibia intramedullary nail was placed with the aid of intraoperative blocking screws, in view of the proximal fracture, to achieve a better alignment for fracture fixation (Figure 5). The operation was uneventful.
Figure 4. Postoperative x-ray showing fixation with a tibia intramedullary nail.
52
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
Figure 5. Intraoperative use of blocking screws to ensure the alignment of the fracture during intramedullar nail insertion.
The histology of the reaming material of the left tibia showed fragments of bony trabeculae and fibro-fatty tissue admixed with blood and fibrin. Small amounts of variably-sized aggregates of light basophilic crystalline deposits rimmed by histiocytes and foreign type giant cells were also seen. Needle shaped negatively birefringent crystals were seen under polarized light. There was no evidence of malignancy. Overall, the features were consistent with gouty tophus. Moreover, the bony reaming material also showed a positive culture of Staphylococcus epidermidis and Staphylococcus caprae. All previous septic workup had been negative, with no other primary source of infection identified. The presentation of infection versus gout can be similar. Given the patient's presentation, and with the benefit of doubt, the finding was treated as an infection. With collaboration with our infectious disease team and rheumatologist team, the patient was treated with a 6 week course of antibiotics with monitoring of blood inflammatory markers regularly, and he was started on allopurinol. Bone densitometry scan was arranged to study the bone health of the patient in general. Upon follow-up at 6 months postoperation, the x-ray showed satisfactory healing, and at 1-year postoperation, the x-ray showed remodelling of the bone with gradual resolution of the lytic lesion (Figure 6). The patient could walk unaided. There was no tenderness at the fracture site, and his left knee range of motion was full. He continues to take allopurinol for his gout.
Discussion The prevalence of gouty arthritis in the general population has been estimated at 1.4%, and in some series, with intraosseous involvement of gout in the knee reaching 13.3%.3 However, literature on pathological fracture due to intraosseous gouty tophus is limited. Nguyen et al1 conducted a PubMed search identifying the relevant literature of gouty tophus with pathological fracture, and found only 13 cases reported since 1950, with one case involving the tibia bone; the most commonly reported site found was the patella bone. Gouty tophi are characterized by granulomas which consist of monosodium urate crystals with mono and multinucleated macrophages surrounding it. It was demonstrated that osteoclast activity was enhanced at the gouty tophi,4 and in addition, the monosodium crystal inhibits osteoblast activity and differentiation,5 and thus causing osteolytic lesions which weakens the
structural composition of bone, which can be prone to pathological fractures. Furthermore, in a retrospective cohort study by Tzeng et al6 published in 2016, involving a large population sample size of 130,941, found that gout as a disease entity itself increases the risk of fracture in general. The enzyme xanthine oxidase, which is involved in the degradation of hypoxanthine to xanthine, and xanthine to uric acid, also plays a role in weakening bone. The breakdown of hypoxanthine to xanthine is an oxygen-dependent reaction that results in the production of reactive oxygen species. These reactive oxygen species stimulates osteoclast differentiation and bone resorption, resulting in low bone mass.7 As a result, gout as a disease entity leads to compromised bone health and a gouty tophus further weakens the bony structure. However, it is worth noting that the study by Tzeng et al6 does not evaluate the cases of pathological fracture from gouty tophi specifically, but rather the risk of fracture in patients with gout in general, and thus the low incidence of pathological fracture from intraosseous gout may require further studies to fully understand. Allopurinol, which is an inhibitor of xanthine oxidase, a drug used in gout, lowers the serum urate level. In addition, this drug has been found to increase bone formation in gouty patients.8 Tzeng et al6 also found in their retrospective cohort, that gouty patients using drugs such as allopurinol had a significantly lower risk of fracture in comparison. It is postulated that allopurinol, by inhibiting xanthine oxidase, reduces the level of free reactive oxygen species, which itself inhibits osteoblast differentiation and osteogenic gene expression. Furthermore, it was found that allopurinol increases tissue nonspecific alkaline phosphatase expression and activity. Tissue nonspecific alkaline phosphatase is identified as one of the key enzymes in bone mineralization. As a result, allopurinol promotes osteoblast differentiation and mineralization, with in vitro studies showing increased bone formation up to fourfold.8 The role of allopurinol in the management of gouty tophi pathological fracture may be important in the process of bone healing, as demonstrated in our case by the rather rapid resolution of the osteolytic lesion after treatment. Our case presents an intraosseous gouty tophi with a positive culture, which could be suggestive of a concomitant infection. The other possibility would be a contamination either during the operation, or during the biopsy procedure. Given the circumstances and clinical presentation, he was treated as having a concomitant infection. However, given the low incidence of intraosseous gouty
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
53
Figure 6. One year postoperation x-ray showing healed fracture with gradual resolution of the lytic lesion.
tophi pathological fracture, literature search has found no such cases with concomitant infection reported, though concomitant septic and gouty arthritis has been established, especially in those with medical comorbidities such as steroid use, diabetes mellitus, liver cirrhosis, and renal failure patients.9 The correlation between gouty and septic arthritis may possibly indicate a correlation between intraosseous gouty tophi and infection. Our patient has a history of alcohol dependence (though his liver function was unremarkable), which may be a risk factor for him to develop a concomitant infection. In order to minimize contamination prior to making a diagnosis, less invasive methods can also be considered. Dual energy CT is a promising noninvasive diagnostic tool for gout. This imaging modality analyses the difference in attenuation of the tissue exposed to two different x-ray spectra simultaneously, thus enabling the determination of the composition of the material. In regards to gout, Bongartz et al10 reported a sensitivity and specificity of 0.93 (95% confidence interval: 0.79e0.98) and 0.95 (95% confidence interval: 0.82e0.99), respectively. Dual energy CT thus may prove to be useful, not only as a noninvasive method, but especially in those diagnostically challenging cases, where histological diagnosis may be difficult to obtain. Our case shows an example of a rare cause of pathological fracture, and in particular, a rare site of such conditions. One should bear in mind the possibility of intraosseous gouty tophus when facing a bony lytic lesion, which may be complicated with infection and fracture. The presentation may be so alarming to mimic an aggressive bone lesion in both clinical and radiological features as in our case. There is evidence to suggest that gout as a disease entity increases the risk of fractures in general. The management of the gout with drugs such as allopurinol is just as important, if not more, than surgery, when treating a case of gouty pathological fracture, as it also aids in bone formation. Concomitant septic arthritis and gouty arthritis has been documented in literature, However, concomitant infection in an intraosseous gouty tophi is not well reported. Coexisting infection and osteopenia should be kept in
mind and treated accordingly as well. One should therefore adopt a multidisciplinary approach when managing such conditions. Conflicts of interest The authors have no conflicts of interest relevant to this article. Acknowledgments This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors, and no material support of any kind was received. References 1. Nguyen C, Ea H-K, Palazzo E, et al. Tophaceous gout: an unusual cause of multiple fractures. Scand J Rheumatol 2010;39:93e6. 2. Ramesh C, Umesh K, Gopal L, et al. Intramedullary nailing versus proximal plating in the management of closed extra-articular proximal tibial fracture: a randomized controlled trial. J Orthop Traumatol 2015;16:203e8. 3. Ko KH, Hsu YC, Lee HS, et al. Tophaceous gout of the knee: revisiting MRI patterns in 30 patients. J Clin Rheumatol 2010;16:209e14. 4. Dalbeth N, Smith T, Nicolson B, et al. Enhanced osteoclastogenesis in patients with tophaceous gout: urate crystals promote osteoclast development through interactions with stromal cells. Arthritis Rheum 2008;58:1854e65. 5. Chhana A, Callon KE, Pool B, et al. Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout. Ann Rheum Dis 2011;70:1684e91. 6. Tzeng HE, Lin CC, Wang IK, et al. Gout increases risk of fracture: a nationwide population-based cohort study. Medicine (Baltimore) 2016 Aug;95:e4669. 7. Baek KH, Oh KW, Lee WY, et al. Association of oxidative stress with postmenopausal osteoporosis and the effects of hydrogen peroxide on osteoclast formation in human bone marrow cell cultures. Calcif Tissue Int 2010;87: 226e35. 8. Orriss I, Arnett T, George J, et al. Allopurinol and oxypurinol promote osteoblast differentiation and increase bone formation. Exp Cell Res 2016;342:166e74. 9. Yu KH, Luo SF, Liou LB, et al. Concomitant septic and gouty arthritisdan analysis of 30 cases. Rheumatology (Oxford) 2003;42:1062e6. 10. Bongartz T, Glazebrook K, Kavros S, et al. Diagnosis of gout using dual-energy computed tomography: an accuracy and diagnostic study. Ann Rheum Dis 2015;74(6):1072e7.
Contents lists available at ScienceDirect
Journal of Orthopaedics, Trauma and Rehabilitation Journal homepages: www.e-jotr.com & www.ejotr.org
Case Report
Pathological Fracture of the Proximal Tibia from an Intraosseous Gouty Tophus: A Rare Presentation of Gout 骨內痛風石導致病理性脛骨折的案例 e 一個罕見痛風症的例子 Chan Chi Chiu Dennis*, Chui King Him Tim, Lee Kin Bong Department of Orthopaedics and Traumatology, Queen Elizabeth Hospital, Hong Kong Special Administrative Region
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 December 2016 Received in revised form 8 May 2017 Accepted 15 May 2017
Intraosseous gouty tophus as the cause of pathological fracture is a seldom encountered condition. Not only does the tophus lesion affect the bone, but recent literature has also demonstrated a correlation between bone health in relation to gout as a disease entity, and showed the importance of medical treatment to improve the bone quality in patients with gout. We present a rare case of a pathological fracture due to an intraosseous gouty tophus as the presentation of gout, which imposed a diagnostic challenge, and illustrates the importance of multidisciplinary management in such conditions.
Keywords: fracture fixation gout intramedullary pathological fracture tibial fractures
中 文 摘 要 骨內痛風石是病理性骨折中較為罕見的情況。最近研究文獻指出痛風與骨格健康之間存在相關性, 並顯示出藥 物治療有助改善痛風症患者的骨質量。我們提出一個骨內痛風石導致病理性骨折的案例，以說明其診斷的挑 戰性及多學科管理對此病例的重要性。
Introduction
Case Report
Intraosseous gouty tophus as the cause of pathological fracture is a seldom encountered condition. From the current literature, the majority of the reported cases of intraosseous gouty tophus related pathological fracture occurs at the patella. A literature search by Nguyen et al1 found only 13 cases of pathological fracture from gouty tophi since 1950; seven of which involved the patella bone. We present a case of an intraosseous gouty tophus pathological fracture in a less reported bone; the tibia. The presentation of the patient imposes a diagnostic challenge. The site of the fracture is at around the proximal tibia, which further imposes a technical difficulty in fracture fixation. The management of such cases should be multidisciplinary, which involves the treatment of the fracture, as well as the condition of gout. Recent literature has demonstrated a correlation between the bone health in relation to gout, and also showed the importance of medical treatment for gout in regards to the bone and its formation.
We present a case of a 41-year-old man, with a past medical history of alcohol dependence and mood disorder, who presented with a 1-week history of sudden onset left leg pain, without any history of trauma. He presented with fever, and physical examination showed erythema with tenderness over the proximal left shin. His white blood cell count was elevated to 13.1 109/L, Creactive protein elevated to 240 mg/L, and alkaline phosphatase level elevated to 181 IU/L. His serum urate level was not elevated at 0.49 mmol/L. The x-ray of the left leg showed a proximal tibia lytic lesion with cortical breakage (Figure 1). Contrast computed tomography (CT) of the left leg showed features suggestive of an aggressive bone tumour with pathological fracture and a large extraosseous soft tissue mass (Figure 2). Bone scan showed markedly increased uptake at the proximal third of the left tibia suggestive of a primary bone tumour, and lesions in the right clavicle, left eight to the 10th rib, and right sixth and seventh rib are suggestive of bone secondaries. In addition, it showed increased uptake in bilateral shoulders, elbows, wrists, knees, ankles, and mid feet, which were suggestive of polyarthritis. With such radiological findings showing a high
* Corresponding author. E-mail: [email protected].
http://dx.doi.org/10.1016/j.jotr.2017.05.002 2210-4917/Copyright © 2017, Hong Kong Orthopaedic Association and the Hong Kong College of Orthopaedic Surgeons. Published by Elsevier (Singapore) Pte Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
50
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
Figure 1. X-ray on presentation showing osteolytic lesions over the proximal tibia, with subtle cortical breakage of the cortex.
Figure 2. CT showing an intraosseous mass extending medially and posteriorly outside the tibia bone. Associated fracture can be demonstrated in these films. CT ¼ computed tomography.
suspicion of malignancy, it was decided that the choice of the next investigation was to achieve a histological diagnosis. A biopsy was performed for confirmation of the diagnosis. Meanwhile, the patient was put on a slab for temporarily immobilization of the fracture. The fine needle aspiration was performed under ultrasound guidance, and the histological findings showed no evidence of malignancy, but instead showed gouty tophi. The biopsy was negative for culture, acid fast bacilli, and fungus. CT guided biopsy was also done, and again showed gouty tophus, with no evidence
of malignancy (Figure 3). The patient had not been aware he had gouty arthritis, and the disease was presented as a pathological fracture. After reaching the diagnosis of gouty tophus with pathological fracture at the proximal third of the tibia shaft, we planned to offer operative fixation of the fracture. Plating and intramedullary nailing for fixation of extra-articular proximal tibia fracture have shown comparable results in terms of infection rate, range of motion, mal-union, and nonunion.2 However, in our case, plate
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
51
Figure 3. Clinical photograph showing the planned biopsy site and CT guided image of the biopsy track. CT ¼ computed tomography.
fixation was considered to be less stable for this proximal fracture with a large lytic lesion around. In addition, given the large extraosseous component of the lesion, plate was considered less favourable. The operation of intramedullary nailing was therefore
chosen (Figure 4). A T2 tibia intramedullary nail was placed with the aid of intraoperative blocking screws, in view of the proximal fracture, to achieve a better alignment for fracture fixation (Figure 5). The operation was uneventful.
Figure 4. Postoperative x-ray showing fixation with a tibia intramedullary nail.
52
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
Figure 5. Intraoperative use of blocking screws to ensure the alignment of the fracture during intramedullar nail insertion.
The histology of the reaming material of the left tibia showed fragments of bony trabeculae and fibro-fatty tissue admixed with blood and fibrin. Small amounts of variably-sized aggregates of light basophilic crystalline deposits rimmed by histiocytes and foreign type giant cells were also seen. Needle shaped negatively birefringent crystals were seen under polarized light. There was no evidence of malignancy. Overall, the features were consistent with gouty tophus. Moreover, the bony reaming material also showed a positive culture of Staphylococcus epidermidis and Staphylococcus caprae. All previous septic workup had been negative, with no other primary source of infection identified. The presentation of infection versus gout can be similar. Given the patient's presentation, and with the benefit of doubt, the finding was treated as an infection. With collaboration with our infectious disease team and rheumatologist team, the patient was treated with a 6 week course of antibiotics with monitoring of blood inflammatory markers regularly, and he was started on allopurinol. Bone densitometry scan was arranged to study the bone health of the patient in general. Upon follow-up at 6 months postoperation, the x-ray showed satisfactory healing, and at 1-year postoperation, the x-ray showed remodelling of the bone with gradual resolution of the lytic lesion (Figure 6). The patient could walk unaided. There was no tenderness at the fracture site, and his left knee range of motion was full. He continues to take allopurinol for his gout.
Discussion The prevalence of gouty arthritis in the general population has been estimated at 1.4%, and in some series, with intraosseous involvement of gout in the knee reaching 13.3%.3 However, literature on pathological fracture due to intraosseous gouty tophus is limited. Nguyen et al1 conducted a PubMed search identifying the relevant literature of gouty tophus with pathological fracture, and found only 13 cases reported since 1950, with one case involving the tibia bone; the most commonly reported site found was the patella bone. Gouty tophi are characterized by granulomas which consist of monosodium urate crystals with mono and multinucleated macrophages surrounding it. It was demonstrated that osteoclast activity was enhanced at the gouty tophi,4 and in addition, the monosodium crystal inhibits osteoblast activity and differentiation,5 and thus causing osteolytic lesions which weakens the
structural composition of bone, which can be prone to pathological fractures. Furthermore, in a retrospective cohort study by Tzeng et al6 published in 2016, involving a large population sample size of 130,941, found that gout as a disease entity itself increases the risk of fracture in general. The enzyme xanthine oxidase, which is involved in the degradation of hypoxanthine to xanthine, and xanthine to uric acid, also plays a role in weakening bone. The breakdown of hypoxanthine to xanthine is an oxygen-dependent reaction that results in the production of reactive oxygen species. These reactive oxygen species stimulates osteoclast differentiation and bone resorption, resulting in low bone mass.7 As a result, gout as a disease entity leads to compromised bone health and a gouty tophus further weakens the bony structure. However, it is worth noting that the study by Tzeng et al6 does not evaluate the cases of pathological fracture from gouty tophi specifically, but rather the risk of fracture in patients with gout in general, and thus the low incidence of pathological fracture from intraosseous gout may require further studies to fully understand. Allopurinol, which is an inhibitor of xanthine oxidase, a drug used in gout, lowers the serum urate level. In addition, this drug has been found to increase bone formation in gouty patients.8 Tzeng et al6 also found in their retrospective cohort, that gouty patients using drugs such as allopurinol had a significantly lower risk of fracture in comparison. It is postulated that allopurinol, by inhibiting xanthine oxidase, reduces the level of free reactive oxygen species, which itself inhibits osteoblast differentiation and osteogenic gene expression. Furthermore, it was found that allopurinol increases tissue nonspecific alkaline phosphatase expression and activity. Tissue nonspecific alkaline phosphatase is identified as one of the key enzymes in bone mineralization. As a result, allopurinol promotes osteoblast differentiation and mineralization, with in vitro studies showing increased bone formation up to fourfold.8 The role of allopurinol in the management of gouty tophi pathological fracture may be important in the process of bone healing, as demonstrated in our case by the rather rapid resolution of the osteolytic lesion after treatment. Our case presents an intraosseous gouty tophi with a positive culture, which could be suggestive of a concomitant infection. The other possibility would be a contamination either during the operation, or during the biopsy procedure. Given the circumstances and clinical presentation, he was treated as having a concomitant infection. However, given the low incidence of intraosseous gouty
C.C.D. Chan et al. / Journal of Orthopaedics, Trauma and Rehabilitation 23 (2017) 49e53
53
Figure 6. One year postoperation x-ray showing healed fracture with gradual resolution of the lytic lesion.
tophi pathological fracture, literature search has found no such cases with concomitant infection reported, though concomitant septic and gouty arthritis has been established, especially in those with medical comorbidities such as steroid use, diabetes mellitus, liver cirrhosis, and renal failure patients.9 The correlation between gouty and septic arthritis may possibly indicate a correlation between intraosseous gouty tophi and infection. Our patient has a history of alcohol dependence (though his liver function was unremarkable), which may be a risk factor for him to develop a concomitant infection. In order to minimize contamination prior to making a diagnosis, less invasive methods can also be considered. Dual energy CT is a promising noninvasive diagnostic tool for gout. This imaging modality analyses the difference in attenuation of the tissue exposed to two different x-ray spectra simultaneously, thus enabling the determination of the composition of the material. In regards to gout, Bongartz et al10 reported a sensitivity and specificity of 0.93 (95% confidence interval: 0.79e0.98) and 0.95 (95% confidence interval: 0.82e0.99), respectively. Dual energy CT thus may prove to be useful, not only as a noninvasive method, but especially in those diagnostically challenging cases, where histological diagnosis may be difficult to obtain. Our case shows an example of a rare cause of pathological fracture, and in particular, a rare site of such conditions. One should bear in mind the possibility of intraosseous gouty tophus when facing a bony lytic lesion, which may be complicated with infection and fracture. The presentation may be so alarming to mimic an aggressive bone lesion in both clinical and radiological features as in our case. There is evidence to suggest that gout as a disease entity increases the risk of fractures in general. The management of the gout with drugs such as allopurinol is just as important, if not more, than surgery, when treating a case of gouty pathological fracture, as it also aids in bone formation. Concomitant septic arthritis and gouty arthritis has been documented in literature, However, concomitant infection in an intraosseous gouty tophi is not well reported. Coexisting infection and osteopenia should be kept in
mind and treated accordingly as well. One should therefore adopt a multidisciplinary approach when managing such conditions. Conflicts of interest The authors have no conflicts of interest relevant to this article. Acknowledgments This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors, and no material support of any kind was received. References 1. Nguyen C, Ea H-K, Palazzo E, et al. Tophaceous gout: an unusual cause of multiple fractures. Scand J Rheumatol 2010;39:93e6. 2. Ramesh C, Umesh K, Gopal L, et al. Intramedullary nailing versus proximal plating in the management of closed extra-articular proximal tibial fracture: a randomized controlled trial. J Orthop Traumatol 2015;16:203e8. 3. Ko KH, Hsu YC, Lee HS, et al. Tophaceous gout of the knee: revisiting MRI patterns in 30 patients. J Clin Rheumatol 2010;16:209e14. 4. Dalbeth N, Smith T, Nicolson B, et al. Enhanced osteoclastogenesis in patients with tophaceous gout: urate crystals promote osteoclast development through interactions with stromal cells. Arthritis Rheum 2008;58:1854e65. 5. Chhana A, Callon KE, Pool B, et al. Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout. Ann Rheum Dis 2011;70:1684e91. 6. Tzeng HE, Lin CC, Wang IK, et al. Gout increases risk of fracture: a nationwide population-based cohort study. Medicine (Baltimore) 2016 Aug;95:e4669. 7. Baek KH, Oh KW, Lee WY, et al. Association of oxidative stress with postmenopausal osteoporosis and the effects of hydrogen peroxide on osteoclast formation in human bone marrow cell cultures. Calcif Tissue Int 2010;87: 226e35. 8. Orriss I, Arnett T, George J, et al. Allopurinol and oxypurinol promote osteoblast differentiation and increase bone formation. Exp Cell Res 2016;342:166e74. 9. Yu KH, Luo SF, Liou LB, et al. Concomitant septic and gouty arthritisdan analysis of 30 cases. Rheumatology (Oxford) 2003;42:1062e6. 10. Bongartz T, Glazebrook K, Kavros S, et al. Diagnosis of gout using dual-energy computed tomography: an accuracy and diagnostic study. Ann Rheum Dis 2015;74(6):1072e7.