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research-article2014
FAIXXX10.1177/1071100714547219Foot & Ankle InternationalChen et al
Article
The Prognostic Value of the Hawkins Sign and Diagnostic Value of MRI After Talar Neck Fractures
Foot & Ankle International® 2014, Vol. 35(12) 1255–1261 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714547219 fai.sagepub.com
Hao Chen, MD, PhD1,2, Wenzhou Liu, MM2, Lianfu Deng, MD, PhD1, and Weidong Song, MD, PhD2
Abstract Background: The early diagnosis of avascular necrosis of the talus (AVN) and prediction of ankle function for talar fractures are important. The Hawkins sign, as a radiographic predictor, could exclude the possibility of developing ischemic bone necrosis after talar neck fractures, but its relationship with ankle function remains unclear. The purpose of this study was to illustrate the prognostic effect of the Hawkins sign on ankle function after talar neck fractures and to study the value of early MRI in detecting the AVN changes after talus fractures. Methods: Cases of talar neck fractures between November 2008 and November 2013 were evaluated. The occurrences of the Hawkins sign and AVN were studied. X-ray imaging was performed at multiple time points from the 4th to the 12th week after the fractures, and MRI examinations were used in the Hawkins sign negative group, with the time span ranging from 1.5 to 12 months. AOFAS scores of the Hawkins sign positive and negative groups were compared during the followup. Forty-four cases (48 feet) were evaluated. Results: The occurrence of positive Hawkins sign was 50%, 30%, and 33.3%, the incidence of AVN was 0%, 10%, and 50%, respectively, in type I, type II, and type III and IV talus fractures, respectively. The AOFAS scores showed no statistically significant difference between Hawkins sign positive group and negative group in type I and II fractures. The Hawkins sign positive group had better AOFAS scores than the negative group in type III and IV fractures. However, there was no statistically significant difference between Hawkins sign positive and negative groups when AVN cases were excluded in type III and IV fractures. Conclusion: The Hawkins sign was a reliable predictor excluding the possibility of AVN. It did not have predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures. MRI can diagnose AVN during an earlier period, and we believe Hawkins sign negative patients should undergo MRI examinations 12 weeks after the fractures, especially in high-energy traumatic cases. Level of Evidence: Level III, comparative case series. Keywords: Hawkins sign, talar neck fracture, AVN Avascular necrosis of the talus (AVN) is a serious complication after talus neck fractures. It can lead to talar dome collapse and ankle arthritis, causing ankle instability and pain.4 Early diagnosis of AVN and prediction of ankle function for those patients are important. As a way of judging talar blood supply, the Hawkins sign has been widely used in clinical practice as a predictor excluding the possibility of AVN.2,14 Our hypothesis was that the Hawkins sign could be a predictive marker for better ankle function, unlike the Crescent sign on avascular necrosis of the femoral head (ANFH), which predicts worse hip joint function.11 To investigate the diagnostic value of the Hawkins sign on excluding AVN and the predictive value on ankle function after talar neck fractures, we followed patients who had talar neck fractures for the occurrence of the
Hawkins sign and AVN, and analyzed the relationship between ankle function and the Hawkins sign.
1
Shanghai Institute of Traumatology and Orthopaedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases with Integrated Chinese-Western Medicine, Ruijin Hospital, Jiao Tong University School of Medicine, Shanghai, China 2 Department of Orthopaedics, Sun Yat-Sen Memorial Hospital, Sun YatSen University, Guangdong, China Corresponding Author: Weidong Song, MD, PhD, Sun Yat-Sen Memorial Hospital, Sun YatSen University, Orthopaedics, 107 Yan Jiang West Rd, Guangzhou, Guangdong, CN 510120, China. Email: [email protected]
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Methods
Results
Patients
Occurrence of Hawkins Sign in Different Types of Fractures
Patients who had talar neck fractures from 2008 to 2013 were included in this study. We excluded the patients who were younger than 14 years old, those who had ankle osteoarthritis and other chronic ankle joint diseases, and patients with long-term use of corticosteroids, hyperlipidemia, hyperuricemia, obliterans, SLE, and sickle cell anemia before the injuries. Our study included 29 males and 15 females aged from 17 to 68 years (median, 38.3 years old). Ten feet were type I, 20 feet were type II, and 18 feet were type III and IV fractures based on the Hawkins classification of talar neck fractures.2,4 Relevant additional injury information was collected; it consisted of fractures around talus, such as lateral malleolar fracture, medial malleolar fracture, posterior malleolar fracture, and calcaneal fracture (Table 1).
The Hawkins sign occurred at 6 to 12 weeks after the fractures (average 8 weeks; Figure 1-4). Hawkins type I cases had a higher prevalence of a positive Hawkins sign than type II and type III and IV, and the difference was not statistically significant. Occurrence of Hawkins Sign Type Hawkins type I Hawkins type II Hawkins type III and IV Total
Positive
Negative Total
5 6 6 17
5 14 12 31
Positive Rate (%)
10 20 18 48
50.0 30.0 33.3 35.4
χ2 correction = 1.220, P = .543.
Treatment Ten feet in type I received conservative treatment and underwent cast treatment. The other 38 feet were treated with open reduction and internal fixation. Dual medial and lateral operative approaches were used in 19 feet. Fourteen feet were treated through a single medial approach, and a single lateral approach was used in the remaining 5 feet (Table 1).
Follow-Up and Function Evaluation X-ray imaging of the ankle was performed at multiple time points from week 4 to week 12 postfracture. All the radiographs were non-weight-bearing. In the Hawkins sign negative patients, MRI examinations were used, with the time span ranging from 1.5 to 12 months. The ankle function was evaluated during the 3rd, 6th, and 12th months after the fractures using the AOFAS ankle hindfoot system.9 During follow-up, X-rays were performed in every patient to identify the appearance of the Hawkins sign (transparent line below the talar dome on the posterior-anterior X-ray) and monitor the development of AVN that was diagnosed when the X-ray manifested an increase in the talar dome opacity (sclerosis), sometimes followed by deformity or articular collapse and bone fragmentation.2,3 At the end of follow-up, the AOFAS scores and MRI presentation were compared.
Data Processing and Statistical Methods Data were processed and analyzed using the t test and chisquare test. A P value less than .05 was considered statistically significant. All analyses were performed in SPSS 19.0.
AVN Incidence of Type II and Type III and IV Cases None of the patients with Hawkins type I fractures developed AVN. Two cases of the 20 type II fractures and 9 of the 18 type III and IV fractures developed AVN. The Hawkins type III and IV fractures had a higher incidence of AVN than Hawkins type II fractures. The differences were statistically significant. AVN incidence of Type II and Type III and IV cases Type Hawkins type II Hawkins type III and IV Total
AVN+ AVN– Total AVN Rate (%) 2 9 11
18 9 27
20 18 38
10.0 50.0 25.5
χ2 correction = 7.370, P = .007.
Comparison of AOFAS Scores Between Positive and Negative Cases The ankle function was evaluated during the 3rd, 6th, and 12th months after the fractures using the AOFAS score (Table 1). In the 48 feet, 11 developed AVN. The 37 patients without AVN were divided into Hawkins sign positive and negative groups based on the different types of fractures. The independent-samples t test was used to compare the AOFAS scores at different time points in Hawkins type I, type II, and type III and IV fractures. The AOFAS scores of the Hawkins sign positive group and negative group were compared at the 3rd, 6th, and 12th months after the fractures. No statistical difference was found in type I and type
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Chen et al Table 1. AOFAS Scores of Talar Neck Fracture Patients. Type No.
AOFAS Score 3 Months
6 Months
Hawkins type I, 10 cases 1 64 2 61 3 58 4 58 5 62 6 65 7 62 8 61 9 62 10 62 Hawkins type II, 20 cases 1 58 2 55 3 62 4 52 5 53 6 55 7 57 8 65 9 55 10 53 11 55 12 63 13 57 14 65 15 53 16 55 17 52 18 58 19 55 20 57 Hawkins type III and IV, 18 cases 1 20 2 44 3 49 4 46 5 45 6 22 7 18 8 21 9 41 10 38 11 55 12 32 13 28 14 22 15 32 16 46 17 28 18 32
Operative Approach
12 Months
Hawkins Sign
Additional Injuries
93 92 92 93 91 92 90 91 92 91
97 96 96 96 96 97 95 95 96 97
P P N N P N P N N P
86 87 90 75 87 85 89 85 86 87 85 92 85 91 85 89 73 85 87 90
96 95 96 76 93 96 93 95 96 96 96 96 93 96 93 96 76 96 96 97
N P N N P N N P N N N N N P N N N P P N
M M&L L M L M M&L M M M M&L M M&L M&L M M L L M L
Lateral malleolar fracture Lateral malleolar fracture Posterior malleolar fracture Calcaneal fracture Calcaneal fracture
52 65 73 76 76 61 49 52 72 65 78 65 57 61 49 78 41 55
62 77 85 87 91 52 51 48 85 76 92 49 61 53 51 85 47 78
N P N P P N N N P P P N N N N N N N
M M&L M&L M&L M&L M&L M M&L M&L M&L M&L M&L M M&L M&L M M&L M&L
Bimalleolar fracture Medial malleolar fracture Pilon fracture Posterior malleolar fracture Calcaneal fracture Lateral malleolar fracture
N = 48. L, lateral; M, medial; N, negative; P, positive.
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Table 2. The Relationship of AOFAS Score Between Positive and Negative Hawkins Sign Groups in Hawkins Type I and Type II Talar Neck Fracture Patients. Hawkins Type I
Hawkins Type II
Variable Group
t Value
P Value
t Value
P Value
3rd month 6th month 12th month
0.995 –1.000 0.408
.349 .347 .694
1.286 0.651 0.872
.215 .523 .395
Table 3. The Relationship of AOFAS Score Between Positive and Negative Hawkins Sign Groups in Hawkins Type III and IV Talar Neck Fracture Patients. With AVN Cases
Without AVN Cases
Variable Group
t Value
P Value
t Value
P Value
3rd month 6th month 12th month
3.547 3.057 3.904
.003 .008 .001
0.514 0.582 0.459
.623 .579 .660
II fractures (Table 2). The difference was statistically significant between the positive and negative groups in type III and IV fractures. However, when the AVN cases were excluded from the data, scores between the Hawkins sign positive and negative groups showed no statistically significant differences (Table 3).
MRI Results in Hawkins Sign Negative Cases MRI scans from 20 cases were collected from 31 Hawkins sign negative cases, with a time span ranging from 1.5 to 12 months. Five cases underwent MRI less than 2 months after the fractures. These patients had significant edema, and we were not able to determine the source. The others underwent MRIs more than 3 months after the fractures. The edema under the talar dome was significantly reduced in AVN negative cases; however, it could have still existed around fracture lines and fixation devices (Figure 5). In AVN positive cases, the edema under the talar dome showed no signs of regression, and then showed abnormal focal signals under the articular surface: the T1-weighted MR image demonstrated a serpiginous low-intensity signal line around the normal bone marrow in the talar dome, and T2-weighted MR image showed a high-intensity signal line in the talar dome that outlined an avascular segment (Figure 6,7).
Discussion The talus is vulnerable to AVN, due to its unique structure, characteristic extraosseous arterial sources, and variable intraosseous blood supply.6 Talar neck fractures are rare
Figure 1. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 29 years old, Hawkins type I, 7 weeks after the fracture.
injuries that account for 2% of foot fractures but are associated with an exceedingly high rate of AVN.8 Our study and many reports have shown that the Hawkins sign can be used as a radiographic marker that excludes the development of AVN. The sign becomes evident 6 to 8 weeks after the injury and represents an area of disuse osteopenia caused by resorption of the subchondral bone and is visualized as a thin subchondral radiolucent line along all or part of the talar dome.14 We provided all 4 types of Hawkins sign positive graphics. However, the cases in our study had a positive Hawkins sign at 6 to 12 weeks after injury, and a partial Hawkins sign was found in 4 cases in our group. We believe that the time the Hawkins sign becomes evident may be later than previous studies have reported, and the partial Hawkins sign was associated with incomplete avascular necrosis, as reported by Tehranzadeh et al.13 Theoretically, the positive Hawkins sign may indicate a better prognosis than its absence if the AVN cases had poor prognosis. A negative Hawkins sign indicates the possibility of developing AVN; thus patients with a negative Hawkins sign should be monitored carefully. Early diagnosis of AVN is important. A study by Kubo showed that MRI can detect bone necrosis in the early postoperative period; but he
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Figure 2. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 32 years old, Hawkins type II, 6 weeks after the fracture.
Figure 3. Hawkins sign positive cases in 4 types of the talar neck fractures. A female, 46 years old, Hawkins type III, 10 weeks after the fracture.
followed only 2 cases and did not compare the Hawkins sign with the MRI in determining the function of the ankle follow-up.7 Our study also showed that MRI can discover AVN earlier than X-ray. A study by Thordarson et al showed that the scans should not be obtained less than 3 weeks after injury.15 Rios et al showed the edema began to regress at 3 weeks and almost resolved 2 months after the injury in most cases.12 In our study, we obtained similar results. Furthermore, we found in some severe type III and IV cases, the edema resolved time needed to be a little longer, and it is better to perform the MRI 3 months after the fractures. We showed the MRI of an AVN negative case, which was performed 1.5 and 3 months after the fractures, and found that the edema disappeared in the talar dome 3 months postoperation. These findings suggest that MRI should be performed in the patients with negative Hawkins sign to detect AVN at an earlier stage (3 months after fractures) so that further treatment could be considered to try to avoid talar dome collapse and ankle arthritis.1,5,10 The Hawkins sign has a similar appearance as the Crescent sign in AVN of the femoral head (AVFH), which is a curvilinear subchondral radiolucent line along the anterolateral aspect of the proximal femoral head. The Crescent sign indicates a third stage of AVFH (Ficat classification)
Figure 4. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 33 years old, Hawkins type IV, 7 weeks after the fracture.
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Figure 6. A female, 28 years old, Hawkins type III fracture. X-ray and MRI were performed 12 months after the fracture and indicated AVN. X-ray shows high density of the talus.
Figure 7. A female, 28 years old, Hawkins type III fracture, X-ray and MRI were performed 12 months after the fracture and indicated AVN. T1-weighted MR image shows low-density signal line in the talar dome; T2-weighted MR image shows highdensity signal line that outlines an avascular segment.
Figure 5. A male, 31 years old, Hawkins type III fracture. (a) Preoperative X-ray and CT scans. (b) X-rays 2 weeks after the fracture. (c) X-rays 6 weeks after the fracture; the Hawkins sign is negative. (d) MRI 6 weeks after the fracture; the edema was significant and was seen under the talar dome, around fracture lines and fixation devices. (e) MRI 3 months after the fracture; the edema under the talar dome was significantly reduced, and only a small amount still existed around fracture lines and fixation devices. (f) MRI 6 months after the fracture; the edema was further reduced, and no signs of AVN were present.
during with femoral head collapse will occur thereby predicting worse hip joint function.11 However, our study suggested that, unlike the Crescent sign in AVFH, the Hawkins sign had no predictive value on ankle function in type I
and type II fractures (low-energy fractures) but predicted a better ankle function in type III and IV fractures (highenergy fractures). In other words, a negative Hawkins sign may predict worse ankle function in type III and IV fractures as expected, as it may indicate the presence of AVN. Interestingly, the scores between Hawkins sign positive and negative groups in type III and IV fractures showed no difference when AVN cases were excluded. We considered it to be the development of AVN, which will result in arthritis and worsened function of the ankle. In addition, the associated cartilage and ligamentous injury may appear more frequently in the high-energy trauma cases. There are some limitations of this study. In some cases, additional injuries may have had an influence on the ankle function. We tried to make sure every MRI was performed less than 12 months after the fractures, but there were still some cases of delayed imaging due to patients’ personal reasons.
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Chen et al In conclusion, we believe the Hawkins sign is a reliable predictor excluding the possibility of AVN. A positive Hawkins sign has no predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures. MRI can diagnose AVN at an earlier stage; thus we believe the Hawkins sign negative patients should undergo MRI examination 12 weeks after fracture, especially in high-energy traumatic cases. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Adelaar RS, Madrian JR. Avascular necrosis of the talus. Orthop Clin North Am. 2004;3(35):383-395. 2. Canale ST, Kelly FB Jr. Fractures of the neck of the talus. J Bone Joint Surg Am. 1978;60:143-156. 3. Christman RA, Cohen R. Osteonecrosis and osteochondrosis. In: Foot and Ankle Radiology. St Louis, MO: Churchill Livingstone; 2003:452-481. 4. Hawkins LG. Fractures of the neck of the talus. J Bone Joint Surg Am. 1970;52:991-1002. 5. Horst F, Gilbert BJ, Nunley JA. Avascular necrosis of the talus: current treatment options. Foot Ankle Clin. 2004;4(9): 757-773.
6. Kelly PJ, Sullivan CR. Blood supply of the talus. Clin Orthop. 1963;30:37-44. 7. Kubo T, Kamata K, Noguchi M, Inoue S. Predictive value of magnetic resonance imaging in avascular necrosis following talar fractures. J Orthop Surg (Hong Kong). 2000;1(8):73-78. 8. Lindvall E, Haidukewych G, DiPasquale T, Herscovici D Jr, Sanders R. Open reduction and stable fixation of isolated, displaced talar neck and body fractures. J Bone Joint Surg Am. 2004;86:2229-2234 9. Madeley NJ, Wing KJ, Topliss C, et al. Responsiveness and validity of the SF-36, Ankle Osteoarthritis Scale, AOFAS Ankle Hindfoot Score, and Foot Function Index in end stage ankle arthritis. Foot Ankle Int. 2012;1(33):57-63. 10. Mont MA, Schon LC, Hungerford MW. Avascular necrosis of the talus treated by core decompression. J Bone Joint Surg Br. 1996;5(78):827-830. 11. Ohzono K, Saito M, Takaoka K, et al. Natural history of nontraumatic avascular necrosis of the femoral head. J Bone Joint Surg Br. 1991;73(1):68-72. 12. Rios AM, Rosenberg ZS, Bencardino JT, et al. Bone marrow edema patterns in the ankle and hindfoot: distinguishing MRI features. Am J Roentgenol. 2011;197:720-729. 13. Tehranzadeh J, Stuffman E, Ross SDK. Partial Hawkins sign in fractures of the talus: a report of three cases. Am J Roentgenol. 2003;6(181):1559-1563. 14. Tezval M, Dumont C, Sturmer KM. Prognostic reliability of the Hawkins sign in fractures of the talus. J Orthop Trauma. 2007;8:538-543. 15. Thordarson DB, Triffon MJ, Terk MR. Magnetic resonance imaging to detect avascular necrosis after open reduction and internal fixation of talar neck fractures. Foot Ankle Int. 1996;17:742-747.
Downloaded from fai.sagepub.com at WAKE FOREST UNIV on January 6, 2015
research-article2014
FAIXXX10.1177/1071100714547219Foot & Ankle InternationalChen et al
Article
The Prognostic Value of the Hawkins Sign and Diagnostic Value of MRI After Talar Neck Fractures
Foot & Ankle International® 2014, Vol. 35(12) 1255–1261 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1071100714547219 fai.sagepub.com
Hao Chen, MD, PhD1,2, Wenzhou Liu, MM2, Lianfu Deng, MD, PhD1, and Weidong Song, MD, PhD2
Abstract Background: The early diagnosis of avascular necrosis of the talus (AVN) and prediction of ankle function for talar fractures are important. The Hawkins sign, as a radiographic predictor, could exclude the possibility of developing ischemic bone necrosis after talar neck fractures, but its relationship with ankle function remains unclear. The purpose of this study was to illustrate the prognostic effect of the Hawkins sign on ankle function after talar neck fractures and to study the value of early MRI in detecting the AVN changes after talus fractures. Methods: Cases of talar neck fractures between November 2008 and November 2013 were evaluated. The occurrences of the Hawkins sign and AVN were studied. X-ray imaging was performed at multiple time points from the 4th to the 12th week after the fractures, and MRI examinations were used in the Hawkins sign negative group, with the time span ranging from 1.5 to 12 months. AOFAS scores of the Hawkins sign positive and negative groups were compared during the followup. Forty-four cases (48 feet) were evaluated. Results: The occurrence of positive Hawkins sign was 50%, 30%, and 33.3%, the incidence of AVN was 0%, 10%, and 50%, respectively, in type I, type II, and type III and IV talus fractures, respectively. The AOFAS scores showed no statistically significant difference between Hawkins sign positive group and negative group in type I and II fractures. The Hawkins sign positive group had better AOFAS scores than the negative group in type III and IV fractures. However, there was no statistically significant difference between Hawkins sign positive and negative groups when AVN cases were excluded in type III and IV fractures. Conclusion: The Hawkins sign was a reliable predictor excluding the possibility of AVN. It did not have predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures. MRI can diagnose AVN during an earlier period, and we believe Hawkins sign negative patients should undergo MRI examinations 12 weeks after the fractures, especially in high-energy traumatic cases. Level of Evidence: Level III, comparative case series. Keywords: Hawkins sign, talar neck fracture, AVN Avascular necrosis of the talus (AVN) is a serious complication after talus neck fractures. It can lead to talar dome collapse and ankle arthritis, causing ankle instability and pain.4 Early diagnosis of AVN and prediction of ankle function for those patients are important. As a way of judging talar blood supply, the Hawkins sign has been widely used in clinical practice as a predictor excluding the possibility of AVN.2,14 Our hypothesis was that the Hawkins sign could be a predictive marker for better ankle function, unlike the Crescent sign on avascular necrosis of the femoral head (ANFH), which predicts worse hip joint function.11 To investigate the diagnostic value of the Hawkins sign on excluding AVN and the predictive value on ankle function after talar neck fractures, we followed patients who had talar neck fractures for the occurrence of the
Hawkins sign and AVN, and analyzed the relationship between ankle function and the Hawkins sign.
1
Shanghai Institute of Traumatology and Orthopaedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases with Integrated Chinese-Western Medicine, Ruijin Hospital, Jiao Tong University School of Medicine, Shanghai, China 2 Department of Orthopaedics, Sun Yat-Sen Memorial Hospital, Sun YatSen University, Guangdong, China Corresponding Author: Weidong Song, MD, PhD, Sun Yat-Sen Memorial Hospital, Sun YatSen University, Orthopaedics, 107 Yan Jiang West Rd, Guangzhou, Guangdong, CN 510120, China. Email: [email protected]
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Methods
Results
Patients
Occurrence of Hawkins Sign in Different Types of Fractures
Patients who had talar neck fractures from 2008 to 2013 were included in this study. We excluded the patients who were younger than 14 years old, those who had ankle osteoarthritis and other chronic ankle joint diseases, and patients with long-term use of corticosteroids, hyperlipidemia, hyperuricemia, obliterans, SLE, and sickle cell anemia before the injuries. Our study included 29 males and 15 females aged from 17 to 68 years (median, 38.3 years old). Ten feet were type I, 20 feet were type II, and 18 feet were type III and IV fractures based on the Hawkins classification of talar neck fractures.2,4 Relevant additional injury information was collected; it consisted of fractures around talus, such as lateral malleolar fracture, medial malleolar fracture, posterior malleolar fracture, and calcaneal fracture (Table 1).
The Hawkins sign occurred at 6 to 12 weeks after the fractures (average 8 weeks; Figure 1-4). Hawkins type I cases had a higher prevalence of a positive Hawkins sign than type II and type III and IV, and the difference was not statistically significant. Occurrence of Hawkins Sign Type Hawkins type I Hawkins type II Hawkins type III and IV Total
Positive
Negative Total
5 6 6 17
5 14 12 31
Positive Rate (%)
10 20 18 48
50.0 30.0 33.3 35.4
χ2 correction = 1.220, P = .543.
Treatment Ten feet in type I received conservative treatment and underwent cast treatment. The other 38 feet were treated with open reduction and internal fixation. Dual medial and lateral operative approaches were used in 19 feet. Fourteen feet were treated through a single medial approach, and a single lateral approach was used in the remaining 5 feet (Table 1).
Follow-Up and Function Evaluation X-ray imaging of the ankle was performed at multiple time points from week 4 to week 12 postfracture. All the radiographs were non-weight-bearing. In the Hawkins sign negative patients, MRI examinations were used, with the time span ranging from 1.5 to 12 months. The ankle function was evaluated during the 3rd, 6th, and 12th months after the fractures using the AOFAS ankle hindfoot system.9 During follow-up, X-rays were performed in every patient to identify the appearance of the Hawkins sign (transparent line below the talar dome on the posterior-anterior X-ray) and monitor the development of AVN that was diagnosed when the X-ray manifested an increase in the talar dome opacity (sclerosis), sometimes followed by deformity or articular collapse and bone fragmentation.2,3 At the end of follow-up, the AOFAS scores and MRI presentation were compared.
Data Processing and Statistical Methods Data were processed and analyzed using the t test and chisquare test. A P value less than .05 was considered statistically significant. All analyses were performed in SPSS 19.0.
AVN Incidence of Type II and Type III and IV Cases None of the patients with Hawkins type I fractures developed AVN. Two cases of the 20 type II fractures and 9 of the 18 type III and IV fractures developed AVN. The Hawkins type III and IV fractures had a higher incidence of AVN than Hawkins type II fractures. The differences were statistically significant. AVN incidence of Type II and Type III and IV cases Type Hawkins type II Hawkins type III and IV Total
AVN+ AVN– Total AVN Rate (%) 2 9 11
18 9 27
20 18 38
10.0 50.0 25.5
χ2 correction = 7.370, P = .007.
Comparison of AOFAS Scores Between Positive and Negative Cases The ankle function was evaluated during the 3rd, 6th, and 12th months after the fractures using the AOFAS score (Table 1). In the 48 feet, 11 developed AVN. The 37 patients without AVN were divided into Hawkins sign positive and negative groups based on the different types of fractures. The independent-samples t test was used to compare the AOFAS scores at different time points in Hawkins type I, type II, and type III and IV fractures. The AOFAS scores of the Hawkins sign positive group and negative group were compared at the 3rd, 6th, and 12th months after the fractures. No statistical difference was found in type I and type
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Chen et al Table 1. AOFAS Scores of Talar Neck Fracture Patients. Type No.
AOFAS Score 3 Months
6 Months
Hawkins type I, 10 cases 1 64 2 61 3 58 4 58 5 62 6 65 7 62 8 61 9 62 10 62 Hawkins type II, 20 cases 1 58 2 55 3 62 4 52 5 53 6 55 7 57 8 65 9 55 10 53 11 55 12 63 13 57 14 65 15 53 16 55 17 52 18 58 19 55 20 57 Hawkins type III and IV, 18 cases 1 20 2 44 3 49 4 46 5 45 6 22 7 18 8 21 9 41 10 38 11 55 12 32 13 28 14 22 15 32 16 46 17 28 18 32
Operative Approach
12 Months
Hawkins Sign
Additional Injuries
93 92 92 93 91 92 90 91 92 91
97 96 96 96 96 97 95 95 96 97
P P N N P N P N N P
86 87 90 75 87 85 89 85 86 87 85 92 85 91 85 89 73 85 87 90
96 95 96 76 93 96 93 95 96 96 96 96 93 96 93 96 76 96 96 97
N P N N P N N P N N N N N P N N N P P N
M M&L L M L M M&L M M M M&L M M&L M&L M M L L M L
Lateral malleolar fracture Lateral malleolar fracture Posterior malleolar fracture Calcaneal fracture Calcaneal fracture
52 65 73 76 76 61 49 52 72 65 78 65 57 61 49 78 41 55
62 77 85 87 91 52 51 48 85 76 92 49 61 53 51 85 47 78
N P N P P N N N P P P N N N N N N N
M M&L M&L M&L M&L M&L M M&L M&L M&L M&L M&L M M&L M&L M M&L M&L
Bimalleolar fracture Medial malleolar fracture Pilon fracture Posterior malleolar fracture Calcaneal fracture Lateral malleolar fracture
N = 48. L, lateral; M, medial; N, negative; P, positive.
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Table 2. The Relationship of AOFAS Score Between Positive and Negative Hawkins Sign Groups in Hawkins Type I and Type II Talar Neck Fracture Patients. Hawkins Type I
Hawkins Type II
Variable Group
t Value
P Value
t Value
P Value
3rd month 6th month 12th month
0.995 –1.000 0.408
.349 .347 .694
1.286 0.651 0.872
.215 .523 .395
Table 3. The Relationship of AOFAS Score Between Positive and Negative Hawkins Sign Groups in Hawkins Type III and IV Talar Neck Fracture Patients. With AVN Cases
Without AVN Cases
Variable Group
t Value
P Value
t Value
P Value
3rd month 6th month 12th month
3.547 3.057 3.904
.003 .008 .001
0.514 0.582 0.459
.623 .579 .660
II fractures (Table 2). The difference was statistically significant between the positive and negative groups in type III and IV fractures. However, when the AVN cases were excluded from the data, scores between the Hawkins sign positive and negative groups showed no statistically significant differences (Table 3).
MRI Results in Hawkins Sign Negative Cases MRI scans from 20 cases were collected from 31 Hawkins sign negative cases, with a time span ranging from 1.5 to 12 months. Five cases underwent MRI less than 2 months after the fractures. These patients had significant edema, and we were not able to determine the source. The others underwent MRIs more than 3 months after the fractures. The edema under the talar dome was significantly reduced in AVN negative cases; however, it could have still existed around fracture lines and fixation devices (Figure 5). In AVN positive cases, the edema under the talar dome showed no signs of regression, and then showed abnormal focal signals under the articular surface: the T1-weighted MR image demonstrated a serpiginous low-intensity signal line around the normal bone marrow in the talar dome, and T2-weighted MR image showed a high-intensity signal line in the talar dome that outlined an avascular segment (Figure 6,7).
Discussion The talus is vulnerable to AVN, due to its unique structure, characteristic extraosseous arterial sources, and variable intraosseous blood supply.6 Talar neck fractures are rare
Figure 1. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 29 years old, Hawkins type I, 7 weeks after the fracture.
injuries that account for 2% of foot fractures but are associated with an exceedingly high rate of AVN.8 Our study and many reports have shown that the Hawkins sign can be used as a radiographic marker that excludes the development of AVN. The sign becomes evident 6 to 8 weeks after the injury and represents an area of disuse osteopenia caused by resorption of the subchondral bone and is visualized as a thin subchondral radiolucent line along all or part of the talar dome.14 We provided all 4 types of Hawkins sign positive graphics. However, the cases in our study had a positive Hawkins sign at 6 to 12 weeks after injury, and a partial Hawkins sign was found in 4 cases in our group. We believe that the time the Hawkins sign becomes evident may be later than previous studies have reported, and the partial Hawkins sign was associated with incomplete avascular necrosis, as reported by Tehranzadeh et al.13 Theoretically, the positive Hawkins sign may indicate a better prognosis than its absence if the AVN cases had poor prognosis. A negative Hawkins sign indicates the possibility of developing AVN; thus patients with a negative Hawkins sign should be monitored carefully. Early diagnosis of AVN is important. A study by Kubo showed that MRI can detect bone necrosis in the early postoperative period; but he
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Figure 2. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 32 years old, Hawkins type II, 6 weeks after the fracture.
Figure 3. Hawkins sign positive cases in 4 types of the talar neck fractures. A female, 46 years old, Hawkins type III, 10 weeks after the fracture.
followed only 2 cases and did not compare the Hawkins sign with the MRI in determining the function of the ankle follow-up.7 Our study also showed that MRI can discover AVN earlier than X-ray. A study by Thordarson et al showed that the scans should not be obtained less than 3 weeks after injury.15 Rios et al showed the edema began to regress at 3 weeks and almost resolved 2 months after the injury in most cases.12 In our study, we obtained similar results. Furthermore, we found in some severe type III and IV cases, the edema resolved time needed to be a little longer, and it is better to perform the MRI 3 months after the fractures. We showed the MRI of an AVN negative case, which was performed 1.5 and 3 months after the fractures, and found that the edema disappeared in the talar dome 3 months postoperation. These findings suggest that MRI should be performed in the patients with negative Hawkins sign to detect AVN at an earlier stage (3 months after fractures) so that further treatment could be considered to try to avoid talar dome collapse and ankle arthritis.1,5,10 The Hawkins sign has a similar appearance as the Crescent sign in AVN of the femoral head (AVFH), which is a curvilinear subchondral radiolucent line along the anterolateral aspect of the proximal femoral head. The Crescent sign indicates a third stage of AVFH (Ficat classification)
Figure 4. Hawkins sign positive cases in 4 types of the talar neck fractures. A male, 33 years old, Hawkins type IV, 7 weeks after the fracture.
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Figure 6. A female, 28 years old, Hawkins type III fracture. X-ray and MRI were performed 12 months after the fracture and indicated AVN. X-ray shows high density of the talus.
Figure 7. A female, 28 years old, Hawkins type III fracture, X-ray and MRI were performed 12 months after the fracture and indicated AVN. T1-weighted MR image shows low-density signal line in the talar dome; T2-weighted MR image shows highdensity signal line that outlines an avascular segment.
Figure 5. A male, 31 years old, Hawkins type III fracture. (a) Preoperative X-ray and CT scans. (b) X-rays 2 weeks after the fracture. (c) X-rays 6 weeks after the fracture; the Hawkins sign is negative. (d) MRI 6 weeks after the fracture; the edema was significant and was seen under the talar dome, around fracture lines and fixation devices. (e) MRI 3 months after the fracture; the edema under the talar dome was significantly reduced, and only a small amount still existed around fracture lines and fixation devices. (f) MRI 6 months after the fracture; the edema was further reduced, and no signs of AVN were present.
during with femoral head collapse will occur thereby predicting worse hip joint function.11 However, our study suggested that, unlike the Crescent sign in AVFH, the Hawkins sign had no predictive value on ankle function in type I
and type II fractures (low-energy fractures) but predicted a better ankle function in type III and IV fractures (highenergy fractures). In other words, a negative Hawkins sign may predict worse ankle function in type III and IV fractures as expected, as it may indicate the presence of AVN. Interestingly, the scores between Hawkins sign positive and negative groups in type III and IV fractures showed no difference when AVN cases were excluded. We considered it to be the development of AVN, which will result in arthritis and worsened function of the ankle. In addition, the associated cartilage and ligamentous injury may appear more frequently in the high-energy trauma cases. There are some limitations of this study. In some cases, additional injuries may have had an influence on the ankle function. We tried to make sure every MRI was performed less than 12 months after the fractures, but there were still some cases of delayed imaging due to patients’ personal reasons.
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Chen et al In conclusion, we believe the Hawkins sign is a reliable predictor excluding the possibility of AVN. A positive Hawkins sign has no predictive value on the ankle function in low-energy fractures and may predict better ankle function in high-energy fractures. MRI can diagnose AVN at an earlier stage; thus we believe the Hawkins sign negative patients should undergo MRI examination 12 weeks after fracture, especially in high-energy traumatic cases. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
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6. Kelly PJ, Sullivan CR. Blood supply of the talus. Clin Orthop. 1963;30:37-44. 7. Kubo T, Kamata K, Noguchi M, Inoue S. Predictive value of magnetic resonance imaging in avascular necrosis following talar fractures. J Orthop Surg (Hong Kong). 2000;1(8):73-78. 8. Lindvall E, Haidukewych G, DiPasquale T, Herscovici D Jr, Sanders R. Open reduction and stable fixation of isolated, displaced talar neck and body fractures. J Bone Joint Surg Am. 2004;86:2229-2234 9. Madeley NJ, Wing KJ, Topliss C, et al. Responsiveness and validity of the SF-36, Ankle Osteoarthritis Scale, AOFAS Ankle Hindfoot Score, and Foot Function Index in end stage ankle arthritis. Foot Ankle Int. 2012;1(33):57-63. 10. Mont MA, Schon LC, Hungerford MW. Avascular necrosis of the talus treated by core decompression. J Bone Joint Surg Br. 1996;5(78):827-830. 11. Ohzono K, Saito M, Takaoka K, et al. Natural history of nontraumatic avascular necrosis of the femoral head. J Bone Joint Surg Br. 1991;73(1):68-72. 12. Rios AM, Rosenberg ZS, Bencardino JT, et al. Bone marrow edema patterns in the ankle and hindfoot: distinguishing MRI features. Am J Roentgenol. 2011;197:720-729. 13. Tehranzadeh J, Stuffman E, Ross SDK. Partial Hawkins sign in fractures of the talus: a report of three cases. Am J Roentgenol. 2003;6(181):1559-1563. 14. Tezval M, Dumont C, Sturmer KM. Prognostic reliability of the Hawkins sign in fractures of the talus. J Orthop Trauma. 2007;8:538-543. 15. Thordarson DB, Triffon MJ, Terk MR. Magnetic resonance imaging to detect avascular necrosis after open reduction and internal fixation of talar neck fractures. Foot Ankle Int. 1996;17:742-747.
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