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Osteochondral lesions of the talar dome associated with trauma
Osteochondral Lesions of the Talar Dome Associated With Trauma Masato Takao, M.D., Mitsuo Ochi, M.D., Yuji Uchio, M.D., Kohei Naito, M.D., Taisuke Kono, M.D., and Kazunori Oae, M.D.
Purpose: The purpose of this study was to clarify the differences in the causes of osteochondral lesions (OCL) of the ankle based on the presence of distal fibular fractures and lateral instability of the ankle. Type of Study: Case series. Methods: We evaluated 92 cases of distal fibular fractures and 86 cases of lateral instability of the ankle, including 36 feet with subacute lateral instability of the ankle and 50 feet with chronic lateral instability of the ankle. In diagnosing OCL, we used a combination of magnetic resonance imaging to evaluate the subchondral conditions and ankle arthroscopy to evaluate the chondral conditions. Results: Of a total of 92 distal fibular fractures, 65 cases (70.7%) had OCL at the time of osteosynthesis and 27 did not (29.3%). Among the latter group, 2 developed OCL about 1 year after surgery. Of a total of 86 cases of lateral instability of the ankle, 35 (40.7%) had OCL. Among the subacute cases, 7 of 36 (19.4%) had OCL, versus 28 of 50 cases (56.0%) with chronic lateral instability of the ankle. Conclusions: Our study suggests that recurrent ankle sprains with remaining lateral instability and distal fibular fractures could be one of the causes of OCL of the ankle. Key Words: Osteochondral lesions—Talar dome—Distal fibular fractures— Lateral instability of the ankle.
C
ases of ankle pain and disability have caused doctors to focus on osteochondral lesions (OCL) of the ankle joint. The diagnosis of OCL of the ankle is usually performed using standard radiography,1 magnetic resonance imaging (MRI),2,3 and ankle arthroscopy.4 MRI and ankle arthroscopy, both excellent tools with which to evaluate morphologic changes, have become standard procedures for the diagnosis of ankle disorders. MRI has the advantage of showing intraosseous disorders with little invasion. The distinctive advantage of ankle arthroscopy is that it allows direct visualization of the site of the intra-
From the Department of Orthopaedics, Shimane University School of Medicine (M.T., Y.U., K.N., T.K., K.O.), Shimane; and the Department of Orthopaedic Surgery, Hiroshima University (M.O.), Hiroshima, Japan. Address correspondence and reprint requests to Masato Takao, M.D., Department of Orthopaedics, Shimane University School of Medicine, 89-1, Enya, Izumo, Shimane 693-8501, Japan. E-mail: [email protected] © 2003 by the Arthroscopy Association of North America 0749-8063/03/1910-3502$30.00/0 doi:10.1016/j.arthro.2003.10.019
articular disorders. However, each of these diagnostic tools has limitations with respect to OCL. Standard radiography cannot identify the chondral lesions and may not accurately reflect the integrity of the articular cartilage. MRI can clearly identify the subchondral lesions but cannot always show the chondral lesions because of technologic limitations in visualizing thin cartilage. Conversely, ankle arthroscopy can clearly identify the chondral lesions but cannot clarify the subchondral lesions. Therefore, the combined use of MRI for evaluating the subchondral lesions and ankle arthroscopy for evaluating chondral lesions is necessary for accurate diagnosis of OCL of the ankle.5 Several reports have been published regarding the etiology of OCL of the ankle joint. Many investigators have concluded that OCL of the ankle is primarily traumatic in origin.1,2,4,6-16 However, whether OCL is usually initiated by a single acute trauma or develops gradually after recurrent ankle sprain is still to be determined. Our hypothesis is that a difference may exist between lateral instability of the ankle and distal fibular fractures in regard to how the OCL occurs and develops.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 10 (December), 2003: pp 1061-1067
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M. TAKAO ET AL. TABLE 1. Details of the Patients in All Groups Anterior Talofibular Ligament Disruptions
No. of patients Mean age (range) Male:Female
Distal Fibular Fractures
Total
Subacute
Chronic
92 31 (18-57) 61:31
86 31 (18-47) 49:37
36 29 (18-52) 21:15
50 32 (18-57) 28:22
The purpose of this study was to clarify the association between ankle trauma and OCL occurrence. The further purpose was to investigate the epidemiology and etiology of OCL of the ankle joint associated with distal fibular fractures and anterior talofibular ligament disruptions using MRI and ankle arthroscopy. METHODS In this series, the subjects were all of the patients who experienced distal fibular fracture or lateral instability of the ankle and who visited our institution between September 1995 and March 2000. This is a prospective study, and all subjects provided written informed consent, in accordance with the format recommended by our Institutional Review Board for the use of human subjects. The study included 92 cases of distal fibular fractures and 86 cases of lateral instability of the ankle. All subjects in this series underwent standard radiography, MRI, and ankle arthroscopy. Although the standard method of treatment for slightly displaced distal fibular fractures and lateral instability of the ankle is nonsurgical, reports have been published of residual disability after this initial treatment. To clarify the causes of residual ankle disability and to treat these disorders initially, we performed MRI and ankle arthroscopy on the patients who experienced ankle injuries between 1995 and 2000. In these subjects, we diagnosed the distal fibular fractures using standard anteroposterior and lateral radiographs and mortise views, and classified the fracture patterns according to the Lauge-Hansen classification system.18 The patients included 61 men and 31 women; ages at the time of surgery ranged from 18 to 57 years (mean, 31.0 ⫾ 11.9) (Table 1). All of the subjects in this series were treated surgically with percutaneous screw fixation or with open reduction and internal fixation,19 and ankle arthroscopy was performed during surgery. Lateral instability of the ankle was diagnosed using a stress test with a Telos device (Telos SE). We measured the talar tilt using the telos device before
surgery under local anesthesia. We used the telos device to investigate joint instability under precise and equal situations for each patient. If a 5° or greater difference in inversion stress compared with contralateral side was found, we regarded the case as showing lateral instability of the ankle.20 We classified patients who underwent treatment within 4 weeks of the initial injury as having subacute cases, and those undergoing treatment at 4 weeks or more from the initial injury as having chronic cases. These patients were treated with cast immobilization for 3 weeks or primary suturing followed by 3 weeks of cast immobilization in subacute cases, and with modified Kelikian’s technique21 using gracilis tendon in chronic cases. Ankle arthroscopy confirmed a ligament tear in all cases. The patients included 49 men and 37 women; ages at surgery ranged from 18 to 47 years (mean, 31.4 ⫾ 8.7 years) (Table 1). No significant differences were found in either age or gender between the subacute and chronic groups or between the distal fibular fracture and lateral instability of the ankle groups. The subjects of this series experienced no major complications such as repeat surgeries, prolonged immobilization, diabetes, or previous surgery. OCL is formed as a combination of chondral and subchondral lesions. Because MRI has the advantage of high sensitivity for detecting the latter, we evaluated the subchondral conditions using MRI and the chondral lesions using ankle arthroscopy. MRI was obtained using a 1.5-T superconducting magnetic resonance scanner with a 20-cm extremity coil (Signa, GE Medical System, Millwork, WI). The foot was placed in the neutral position with the ankle in the 0° neutral position. A section thickness of 3 mm was used, with a 0.5-mm intersection gap. Coronal and sagittal planes were obtained. The plane examination protocol consisted of transverse T2-weighted (repetition time/echo time, 4000/96; matrix, 256 ⫻ 256; 2 NEX) fast spin-echo sequences. When a focal area of low signal intensity was detected within the bone
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FIGURE 1. Coronal (left) and sagittal (right) T2-weighted MRI (repetition time, 4,000 ms; echo time, 96 ms) revealed a subchondral lesion at the posteromedial talar dome of the right ankle (arrow).
marrow, a subchondral lesion was considered to be present (Fig 1). Ankle arthroscopy with the patient under spinal anesthesia was performed on all patients to provide a diagnosis regarding the chondral lesion. The patient was placed in a supine position with the hip flexed 45° in a leg holder by means of the bandage distraction technique using a force of 78.4 N.22 This distraction technique enables visualization of the full joint space in the anterolateral and anteromedial portals only. Therefore, the arthroscope was inserted at the anterolateral and anteromedial portals so that the talar dome and other structures could be seen (Fig 2). Based on the MRI and arthroscopic findings, each case of OCL was classified as one of 3 types: those in which normal MRI and abnormal arthroscopy results indicated a chondral lesion; those in which abnormal MRI and normal arthroscopy indicated a subchondral lesion; and those in which abnormal MRI and arthroscopy indicated a chondral-subchondral lesion (Fig 3).5 We then analyzed the distribution of types for each of the distal fibular fractures and lateral instability of the ankle. Finally, we evaluated the rate of OCL for each injury type and clarified the location of OCL. Using chi-square followed by Fisher’s exact test, we statistically analyzed the frequency of the chondral lesion, subchondral lesion, and chondral-subchondral lesion among the supination-
adduction (SA), supination eversion (SE), pronation abduction (PA), and pronation eversion (PE) type fractures, and between the subacute and chronic lateral ligament instability of the ankle.
FIGURE 2. Arthroscopic finding of a chondral lesion at the posteromedial talar dome of the right ankle (arrow).
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FIGURE 3. Classification of OCL based on MRI and arthroscopic findings. Normal MRI and abnormal arthroscopy results indicated a chondral lesion; abnormal MRI and normal arthroscopy indicated a subchondral lesion; abnormal MRI and arthroscopy indicated a chondral-subchondral lesion.
RESULTS
Among the subacute cases, 7 of 36 (19.4%) had OCL, and 28 of 50 cases (56.0%) in the group with chronic lateral instability of the ankle had OCL (Table 2). OCL was more frequent in chronic lateral ligament instabilities than in the subacute cases (P ⬍ .0001). Chondral, subchondral, and chondral-subchondral lesions constituted 71.2%, 14.3%, and 14.3% of subacute cases, respectively; and 7.1%, 25.0%, and 67.9% of chronic cases, respectively (Fig 5). With regard to location, the OCL was located at the posteromedial talar dome, the anterolateral talar dome, the tip of the medial malleolus, and the plafond in 33.3%, 0%, 83.3%, and 16.7%, respectively, of SAtype fractures; in 78.1%, 34.4%, 28.1%, and 9.4%, respectively, of SE-type fractures; in 25.0%, 33.3%, 62.5%, and 20.8%, respectively, of PA-type fractures; and in 100%, 0%, 33.3%, and 0%, respectively, of PE-type fractures among the distal fibular fractures (Fig 6). Posteromedial lesions were more frequent than anterolateral lesions in supination-type fractures (P ⬍ .0001). Conversely, no significant difference was found between the frequency of posteromedial lesions and anterolateral lesions in pronation-type fractures (P ⫽ .2125). In cases of lateral instability of the ankle,
We found 16 feet with the SA type, 41 feet with the SE type, 32 feet with the PA type, and 3 feet with the PE type fractures. Two cases of a PE-type fracture involved dislocated fracture. At the time of osteosynthesis, 65 cases (70.7%) of OCL were found. Among the patients with no OCL at the time of osteosynthesis (27 cases), arthroscopic examination showed 2 cases of OCL (7.4%) at 1 year after surgery (Table 2). Chondral, subchondral, and chondral-subchondral lesions accounted for 66.7%, 16.7%, and 16.7% of SA-type fractures, respectively; 34.4%, 3.1%, and 62.5% of SE-type fractures, respectively; 25.0%, 4.2%, and 70.8% of PA-type fractures, respectively; and 0%, 0%, and 100% of PE-type fractures, respectively (Fig 4). We found that chondral lesions were more frequent in SA-type cases than in the SE-, PA-, and PE-type cases (P ⬍ .0001, respectively). Conversely, chondral-subchondral lesions were more frequent in the SE-, PA-, and PE-type cases than in the SA-type cases (P ⬍ .0001, respectively). Thirty-six feet were diagnosed with subacute lateral instability of the ankle, and 50 feet with chronic lateral instability of the ankle. Of a total of 86 cases of lateral instability of the ankle, 40.7% had OCL.
TABLE 2. Incidence of OCL for Each Injury Type Distal Fibular fractures
Anterior Talofibular Ligament Disruptions
At Osteosynthesis
1 Year Postop
Total
Subacute
Chronic
65/92 (70.7%)
2/27 (7.4%)
35/86 (40.7%)
7/36 (70.7%)
28/50 (56.0%)
OCL OF THE TALAR DOME ASSOCIATED WITH TRAUMA
FIGURE 4. Mortality rate of OCL for the supination-adduction (SA), supination-eversion (SE), pronation-abduction (PA), and pronation-eversion (PE) types of distal fibular fractures.
the OCL was located at the posteromedial talar dome, the anterolateral talar dome, the tip of the medial malleolus, and the plafond in 71.4%, 28.6%, 57.1% and 0%, respectively, of subacute cases; and 75.0%, 25.0%, 46.4%, and 7.1%, respectively, of chronic cases (Fig 7). The location patterns of OCL were similar between the group with subacute and that with chronic lateral instability of the ankle. Some patients had 2 lesions: anterolateral talar dome and tip of the medial malleolus, or posteromedial talar dome and tip of the medial malleolus. The 2 types of lesions were the same in every case. DISCUSSION To diagnose OCL of the ankle, plain-radiographic examination,1 MRI,2,3 and ankle arthroscopy4 are usually performed. Plain radiography is the commonly
FIGURE 5. Mortality rate of OCL for subacute and chronic lateral instability of the ankle.
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FIGURE 6. Location of OCL for the supination-adduction (SA), supination-eversion (SE), pronation-abduction (PA), and pronation-eversion (PE) types of distal fibular fractures. Posteromedial talar dome (PM), anterolateral talar dome (AL), tip of the medial malleolus (Tip), plafond of the tibia (Plafond).
used diagnostic tool because of its low cost and ease of use. However, it cannot show the chondral conditions and may not accurately reflect the integrity of the articular cartilage. MRI is an excellent tool for identifying subchondral lesions. Anderson et al.2 attempted to clarify the usefulness of MRI and concluded that MRI can detect subtle lesions that may represent trabecular compression. Further, De Smet et al.3 examined 14 patients with MRI and compared the predictive intactness of the chondral surface with the arthroscopic findings. They found MRI to be an accurate predictor of fragment stability. Recently, ankle arthroscopy has become a standard procedure for the diagnosis and treatment of ankle disorders. A distinct advantage of ankle arthroscopy is that it allows direct visualization of the site of the ankle disorder. In this
FIGURE 7. Location of OCL for the subacute and chronic lateral instability of the ankle. Posteromedial talar dome (PM), anterolateral talar dome (AL), tip of the medial malleolus (Tip), plafond of the tibia (Plafond).
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way, it allows an accurate evaluation of the chondral conditions, although it does not accurately show the subchondral conditions. Ankle arthroscopy and MRI demand a substantial increase of the economic expenditure of the health care system. However, as far as we know, no better methods exist for diagnosing chondral lesions than arthroscopy and MRI. In our institution, we regard ankle arthroscopy and MRI as necessary tools for the diagnosis of chondral lesions. Therefore, in cases like those described in this report, an accurate diagnosis of OCL of the ankle requires the combined use of MRI for evaluating the subchondral conditions and ankle arthroscopy for evaluating the chondral conditions. Several reports have been published regarding the etiology of OCL of the ankle joint. Many investigators have concluded that OCL of the ankle is primarily traumatic in origin.1,2,4,6-16 Berndt and Harty1 reported that 21 of 24 patients had trauma-associated OCL of the ankle. They suggested that OCL of the ankle joint is almost always associated with an acute traumatic episode. Canale8 reported that all of the lateral lesions in the cohort studies were associated with trauma and 64% of patients with medial lesions had experienced a significant traumatic event. Van Dijk and Scholte16 reported that all lateral lesions are associated with traumatic episode, and 25% of the medial lesions are associated with trauma. Several authors2,4,6,7,9-17 have concurred with this theory, finding that lateral lesions are almost always associated with a traumatic episode while 25% to 80% of medial lesions are associated with trauma. However, whether OCL is usually initiated by a single acute trauma or develops gradually after recurrent ankle sprain remains to be clarified. In the current study, high rates of OCL were found at the time of osteosynthesis. This finding would seem to suggest that most cases of OCL in fractures occur at the time of initial trauma. Conversely, chronic lateral instability of the ankle had a higher rate of OCL than subacute cases. This result suggested that recurrent ankle sprain with remaining lateral instability is one cause of OCL in lateral instability of the ankle. In subacute lateral instability of the ankle, chondral lesions were more frequent than other types of lesions. Conversely, in chronic cases, osteochondral lesions were more frequent than other types. This result suggests that there is little damage to the cartilage and the subchondral bone in the initial injury. Rather, it is the remaining lateral instability that brings the more severe damage to the cartilage and subchondral bone. Regarding the location patterns of the OCL, Berndt
and Harty1 reported the OCL’s location when the anterolateral talar dome impacts the face of the fibula while the ankle is positioned in dorsiflexion and an inversion stress is applied to the joint. When the plantar flexed ankle is subjected to a combination of inversion force and external rotation of the ankle on the tibia, the posteromedial talar dome impacts the tibial articular surface, creating a posteromedial lesion. The current study suggests another mechanism that produces OCLs at the anterolateral or posteromedial parts of the talar dome is when the anterolateral talar dome impacts the face of the fibula while the ankle is positioned in supination and an external rotation stress is applied to the joint or the ankle is positioned in pronation and abduction stress is applied to the joint. An OCL also forms when the posteromedial talar dome impacts the tibial articular surface while the ankle is positioned in supination and an adduction or external rotation force is applied to the joint or the ankle is positioned in pronation and an abduction or external rotation stress is applied to the joint. In conclusion, a high percentage of OCL occurred at the time of initial trauma in distal fibular fractures. Among the cases of lateral instability of the ankle, a higher rate of OCL cases was found in chronic cases than in subacute cases. Our study suggests that recurrent ankle sprain with remaining lateral instability and distal fibular fractures could be one of the causes of OCL of the ankle. REFERENCES 1. Berndt AL, Harty M. Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 1959;41:9881020. 2. Anderson IF, Crichton KJ, Grattan-Smith T, et al. Osteochondral fractures of the dome of the talus. J Bone Joint Surg Am 1989;71:1143-1152. 3. De Smet AA, Fisher DR, Burnstein MI, et al. Value of MR imaging in staging osteochondral lesions of the talus (osteochondritis dissecans): Results in 14 patients. Am J Roentgenol 1990;154:555-558. 4. Pritsch M, Horoshovski H, Farine I. Arthroscopic treatment of osteochondral lesions of the talus. J Bone Joint Surg Am 1986;68:862-865. 5. Takao M, Ochi M, Naito K, et al. Arthroscopic drilling for chondral, subchondral, combined chondral-subchondral lesions of the talar dome. Arthroscopy 2003;19:524-530. 6. Alexander AH, Lichtman DM. Surgical treatment of transchondral talar-dome fractures (osteochondritis dissecans): Long term follow-up. J Bone Joint Surg Am 1980;62:646-652. 7. Baker CL, Andrews JR, Ryan JB. Arhtroscopic treatment of transchondral talar dome fractures. Arthroscopy 1986;2:82-87. 8. Canale ST, Belding RH. Osteochondral lesions of the talus. J Bone Joint Surg Am 1980;62:97-102. 9. Flick AB, Gould N. Osteochondritis dissecans of the talus (transchondral fractures of the talus): Review of the literature
OCL OF THE TALAR DOME ASSOCIATED WITH TRAUMA
10. 11. 12. 13. 14.
15.
and new surgical approach for medial dome lesions. Foot Ankle 1985;5:165-185. Hintermann B, Regazzoni P, Lampert C, et al. Arthroscopic findings in acute fractures of the ankle. J Bone Joint Surg Br 2000;82:345-351. Marks KL. Flake fracture of the talus progressing to osteochondritis dissecans. J Bone Joint Surg Br 1952;34:90-92. Parisien JS. Arthroscopic treatment of osteochondral lesions of the talus. Am J Sports Med 1986;14:211-217. Pettine KA, Morrey BF. Osteochondral fractures of the talus: A long-term follow-up. J Bone Joint Surg Br 1987;69:89-92. Roeden S, Tillegaard P, Unander-Scharin L. Osteochondritis dissecans and similar lesions of the talus: Report of 55 cases with special reference to etiology and treatment. Acta Orthop Scand 1953;23:51-66. Van Buecken K, Barrack RL, Alexander AH. Arthroscopic
16. 17. 18. 19. 20. 21. 22.
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treatment of transchondral talar dome fractures. Am J Sports Med 1989;17:350-356. Van Dijk CN, Scholte D. Arthroscopy of the ankle joint. Arthroscopy 1997;13:90-96. Yvars MF. Osteochondral fractures of the dome of the talus. Clin Orthop 1976;114:185-191. Lauge-Hansen N. Fracture of the ankle: II. Combined experimental-surgical and experimental-roentgenologic investigations. Arch Surg 1950;60:957-985. Schaffer JJ, Manoli A. The antiglide plate for distal fibular fixation. J Bone Joint Surg Am 1987;69:596-604. Cox JS, Hewes TF. Normal talar tilt. Clin Orthop 1979;140:37-41. Kelikian AS. Operative treatment of the foot and ankle. Stamford, Connecticut: Appleton & Lange, 1999. Takao M, Ochi M, Shu N, et al. Bandage distraction technique for ankle arthroscopy. Foot Ankle 1999;20:389-391.
Purpose: The purpose of this study was to clarify the differences in the causes of osteochondral lesions (OCL) of the ankle based on the presence of distal fibular fractures and lateral instability of the ankle. Type of Study: Case series. Methods: We evaluated 92 cases of distal fibular fractures and 86 cases of lateral instability of the ankle, including 36 feet with subacute lateral instability of the ankle and 50 feet with chronic lateral instability of the ankle. In diagnosing OCL, we used a combination of magnetic resonance imaging to evaluate the subchondral conditions and ankle arthroscopy to evaluate the chondral conditions. Results: Of a total of 92 distal fibular fractures, 65 cases (70.7%) had OCL at the time of osteosynthesis and 27 did not (29.3%). Among the latter group, 2 developed OCL about 1 year after surgery. Of a total of 86 cases of lateral instability of the ankle, 35 (40.7%) had OCL. Among the subacute cases, 7 of 36 (19.4%) had OCL, versus 28 of 50 cases (56.0%) with chronic lateral instability of the ankle. Conclusions: Our study suggests that recurrent ankle sprains with remaining lateral instability and distal fibular fractures could be one of the causes of OCL of the ankle. Key Words: Osteochondral lesions—Talar dome—Distal fibular fractures— Lateral instability of the ankle.
C
ases of ankle pain and disability have caused doctors to focus on osteochondral lesions (OCL) of the ankle joint. The diagnosis of OCL of the ankle is usually performed using standard radiography,1 magnetic resonance imaging (MRI),2,3 and ankle arthroscopy.4 MRI and ankle arthroscopy, both excellent tools with which to evaluate morphologic changes, have become standard procedures for the diagnosis of ankle disorders. MRI has the advantage of showing intraosseous disorders with little invasion. The distinctive advantage of ankle arthroscopy is that it allows direct visualization of the site of the intra-
From the Department of Orthopaedics, Shimane University School of Medicine (M.T., Y.U., K.N., T.K., K.O.), Shimane; and the Department of Orthopaedic Surgery, Hiroshima University (M.O.), Hiroshima, Japan. Address correspondence and reprint requests to Masato Takao, M.D., Department of Orthopaedics, Shimane University School of Medicine, 89-1, Enya, Izumo, Shimane 693-8501, Japan. E-mail: [email protected] © 2003 by the Arthroscopy Association of North America 0749-8063/03/1910-3502$30.00/0 doi:10.1016/j.arthro.2003.10.019
articular disorders. However, each of these diagnostic tools has limitations with respect to OCL. Standard radiography cannot identify the chondral lesions and may not accurately reflect the integrity of the articular cartilage. MRI can clearly identify the subchondral lesions but cannot always show the chondral lesions because of technologic limitations in visualizing thin cartilage. Conversely, ankle arthroscopy can clearly identify the chondral lesions but cannot clarify the subchondral lesions. Therefore, the combined use of MRI for evaluating the subchondral lesions and ankle arthroscopy for evaluating chondral lesions is necessary for accurate diagnosis of OCL of the ankle.5 Several reports have been published regarding the etiology of OCL of the ankle joint. Many investigators have concluded that OCL of the ankle is primarily traumatic in origin.1,2,4,6-16 However, whether OCL is usually initiated by a single acute trauma or develops gradually after recurrent ankle sprain is still to be determined. Our hypothesis is that a difference may exist between lateral instability of the ankle and distal fibular fractures in regard to how the OCL occurs and develops.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 10 (December), 2003: pp 1061-1067
1061
1062
M. TAKAO ET AL. TABLE 1. Details of the Patients in All Groups Anterior Talofibular Ligament Disruptions
No. of patients Mean age (range) Male:Female
Distal Fibular Fractures
Total
Subacute
Chronic
92 31 (18-57) 61:31
86 31 (18-47) 49:37
36 29 (18-52) 21:15
50 32 (18-57) 28:22
The purpose of this study was to clarify the association between ankle trauma and OCL occurrence. The further purpose was to investigate the epidemiology and etiology of OCL of the ankle joint associated with distal fibular fractures and anterior talofibular ligament disruptions using MRI and ankle arthroscopy. METHODS In this series, the subjects were all of the patients who experienced distal fibular fracture or lateral instability of the ankle and who visited our institution between September 1995 and March 2000. This is a prospective study, and all subjects provided written informed consent, in accordance with the format recommended by our Institutional Review Board for the use of human subjects. The study included 92 cases of distal fibular fractures and 86 cases of lateral instability of the ankle. All subjects in this series underwent standard radiography, MRI, and ankle arthroscopy. Although the standard method of treatment for slightly displaced distal fibular fractures and lateral instability of the ankle is nonsurgical, reports have been published of residual disability after this initial treatment. To clarify the causes of residual ankle disability and to treat these disorders initially, we performed MRI and ankle arthroscopy on the patients who experienced ankle injuries between 1995 and 2000. In these subjects, we diagnosed the distal fibular fractures using standard anteroposterior and lateral radiographs and mortise views, and classified the fracture patterns according to the Lauge-Hansen classification system.18 The patients included 61 men and 31 women; ages at the time of surgery ranged from 18 to 57 years (mean, 31.0 ⫾ 11.9) (Table 1). All of the subjects in this series were treated surgically with percutaneous screw fixation or with open reduction and internal fixation,19 and ankle arthroscopy was performed during surgery. Lateral instability of the ankle was diagnosed using a stress test with a Telos device (Telos SE). We measured the talar tilt using the telos device before
surgery under local anesthesia. We used the telos device to investigate joint instability under precise and equal situations for each patient. If a 5° or greater difference in inversion stress compared with contralateral side was found, we regarded the case as showing lateral instability of the ankle.20 We classified patients who underwent treatment within 4 weeks of the initial injury as having subacute cases, and those undergoing treatment at 4 weeks or more from the initial injury as having chronic cases. These patients were treated with cast immobilization for 3 weeks or primary suturing followed by 3 weeks of cast immobilization in subacute cases, and with modified Kelikian’s technique21 using gracilis tendon in chronic cases. Ankle arthroscopy confirmed a ligament tear in all cases. The patients included 49 men and 37 women; ages at surgery ranged from 18 to 47 years (mean, 31.4 ⫾ 8.7 years) (Table 1). No significant differences were found in either age or gender between the subacute and chronic groups or between the distal fibular fracture and lateral instability of the ankle groups. The subjects of this series experienced no major complications such as repeat surgeries, prolonged immobilization, diabetes, or previous surgery. OCL is formed as a combination of chondral and subchondral lesions. Because MRI has the advantage of high sensitivity for detecting the latter, we evaluated the subchondral conditions using MRI and the chondral lesions using ankle arthroscopy. MRI was obtained using a 1.5-T superconducting magnetic resonance scanner with a 20-cm extremity coil (Signa, GE Medical System, Millwork, WI). The foot was placed in the neutral position with the ankle in the 0° neutral position. A section thickness of 3 mm was used, with a 0.5-mm intersection gap. Coronal and sagittal planes were obtained. The plane examination protocol consisted of transverse T2-weighted (repetition time/echo time, 4000/96; matrix, 256 ⫻ 256; 2 NEX) fast spin-echo sequences. When a focal area of low signal intensity was detected within the bone
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FIGURE 1. Coronal (left) and sagittal (right) T2-weighted MRI (repetition time, 4,000 ms; echo time, 96 ms) revealed a subchondral lesion at the posteromedial talar dome of the right ankle (arrow).
marrow, a subchondral lesion was considered to be present (Fig 1). Ankle arthroscopy with the patient under spinal anesthesia was performed on all patients to provide a diagnosis regarding the chondral lesion. The patient was placed in a supine position with the hip flexed 45° in a leg holder by means of the bandage distraction technique using a force of 78.4 N.22 This distraction technique enables visualization of the full joint space in the anterolateral and anteromedial portals only. Therefore, the arthroscope was inserted at the anterolateral and anteromedial portals so that the talar dome and other structures could be seen (Fig 2). Based on the MRI and arthroscopic findings, each case of OCL was classified as one of 3 types: those in which normal MRI and abnormal arthroscopy results indicated a chondral lesion; those in which abnormal MRI and normal arthroscopy indicated a subchondral lesion; and those in which abnormal MRI and arthroscopy indicated a chondral-subchondral lesion (Fig 3).5 We then analyzed the distribution of types for each of the distal fibular fractures and lateral instability of the ankle. Finally, we evaluated the rate of OCL for each injury type and clarified the location of OCL. Using chi-square followed by Fisher’s exact test, we statistically analyzed the frequency of the chondral lesion, subchondral lesion, and chondral-subchondral lesion among the supination-
adduction (SA), supination eversion (SE), pronation abduction (PA), and pronation eversion (PE) type fractures, and between the subacute and chronic lateral ligament instability of the ankle.
FIGURE 2. Arthroscopic finding of a chondral lesion at the posteromedial talar dome of the right ankle (arrow).
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FIGURE 3. Classification of OCL based on MRI and arthroscopic findings. Normal MRI and abnormal arthroscopy results indicated a chondral lesion; abnormal MRI and normal arthroscopy indicated a subchondral lesion; abnormal MRI and arthroscopy indicated a chondral-subchondral lesion.
RESULTS
Among the subacute cases, 7 of 36 (19.4%) had OCL, and 28 of 50 cases (56.0%) in the group with chronic lateral instability of the ankle had OCL (Table 2). OCL was more frequent in chronic lateral ligament instabilities than in the subacute cases (P ⬍ .0001). Chondral, subchondral, and chondral-subchondral lesions constituted 71.2%, 14.3%, and 14.3% of subacute cases, respectively; and 7.1%, 25.0%, and 67.9% of chronic cases, respectively (Fig 5). With regard to location, the OCL was located at the posteromedial talar dome, the anterolateral talar dome, the tip of the medial malleolus, and the plafond in 33.3%, 0%, 83.3%, and 16.7%, respectively, of SAtype fractures; in 78.1%, 34.4%, 28.1%, and 9.4%, respectively, of SE-type fractures; in 25.0%, 33.3%, 62.5%, and 20.8%, respectively, of PA-type fractures; and in 100%, 0%, 33.3%, and 0%, respectively, of PE-type fractures among the distal fibular fractures (Fig 6). Posteromedial lesions were more frequent than anterolateral lesions in supination-type fractures (P ⬍ .0001). Conversely, no significant difference was found between the frequency of posteromedial lesions and anterolateral lesions in pronation-type fractures (P ⫽ .2125). In cases of lateral instability of the ankle,
We found 16 feet with the SA type, 41 feet with the SE type, 32 feet with the PA type, and 3 feet with the PE type fractures. Two cases of a PE-type fracture involved dislocated fracture. At the time of osteosynthesis, 65 cases (70.7%) of OCL were found. Among the patients with no OCL at the time of osteosynthesis (27 cases), arthroscopic examination showed 2 cases of OCL (7.4%) at 1 year after surgery (Table 2). Chondral, subchondral, and chondral-subchondral lesions accounted for 66.7%, 16.7%, and 16.7% of SA-type fractures, respectively; 34.4%, 3.1%, and 62.5% of SE-type fractures, respectively; 25.0%, 4.2%, and 70.8% of PA-type fractures, respectively; and 0%, 0%, and 100% of PE-type fractures, respectively (Fig 4). We found that chondral lesions were more frequent in SA-type cases than in the SE-, PA-, and PE-type cases (P ⬍ .0001, respectively). Conversely, chondral-subchondral lesions were more frequent in the SE-, PA-, and PE-type cases than in the SA-type cases (P ⬍ .0001, respectively). Thirty-six feet were diagnosed with subacute lateral instability of the ankle, and 50 feet with chronic lateral instability of the ankle. Of a total of 86 cases of lateral instability of the ankle, 40.7% had OCL.
TABLE 2. Incidence of OCL for Each Injury Type Distal Fibular fractures
Anterior Talofibular Ligament Disruptions
At Osteosynthesis
1 Year Postop
Total
Subacute
Chronic
65/92 (70.7%)
2/27 (7.4%)
35/86 (40.7%)
7/36 (70.7%)
28/50 (56.0%)
OCL OF THE TALAR DOME ASSOCIATED WITH TRAUMA
FIGURE 4. Mortality rate of OCL for the supination-adduction (SA), supination-eversion (SE), pronation-abduction (PA), and pronation-eversion (PE) types of distal fibular fractures.
the OCL was located at the posteromedial talar dome, the anterolateral talar dome, the tip of the medial malleolus, and the plafond in 71.4%, 28.6%, 57.1% and 0%, respectively, of subacute cases; and 75.0%, 25.0%, 46.4%, and 7.1%, respectively, of chronic cases (Fig 7). The location patterns of OCL were similar between the group with subacute and that with chronic lateral instability of the ankle. Some patients had 2 lesions: anterolateral talar dome and tip of the medial malleolus, or posteromedial talar dome and tip of the medial malleolus. The 2 types of lesions were the same in every case. DISCUSSION To diagnose OCL of the ankle, plain-radiographic examination,1 MRI,2,3 and ankle arthroscopy4 are usually performed. Plain radiography is the commonly
FIGURE 5. Mortality rate of OCL for subacute and chronic lateral instability of the ankle.
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FIGURE 6. Location of OCL for the supination-adduction (SA), supination-eversion (SE), pronation-abduction (PA), and pronation-eversion (PE) types of distal fibular fractures. Posteromedial talar dome (PM), anterolateral talar dome (AL), tip of the medial malleolus (Tip), plafond of the tibia (Plafond).
used diagnostic tool because of its low cost and ease of use. However, it cannot show the chondral conditions and may not accurately reflect the integrity of the articular cartilage. MRI is an excellent tool for identifying subchondral lesions. Anderson et al.2 attempted to clarify the usefulness of MRI and concluded that MRI can detect subtle lesions that may represent trabecular compression. Further, De Smet et al.3 examined 14 patients with MRI and compared the predictive intactness of the chondral surface with the arthroscopic findings. They found MRI to be an accurate predictor of fragment stability. Recently, ankle arthroscopy has become a standard procedure for the diagnosis and treatment of ankle disorders. A distinct advantage of ankle arthroscopy is that it allows direct visualization of the site of the ankle disorder. In this
FIGURE 7. Location of OCL for the subacute and chronic lateral instability of the ankle. Posteromedial talar dome (PM), anterolateral talar dome (AL), tip of the medial malleolus (Tip), plafond of the tibia (Plafond).
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way, it allows an accurate evaluation of the chondral conditions, although it does not accurately show the subchondral conditions. Ankle arthroscopy and MRI demand a substantial increase of the economic expenditure of the health care system. However, as far as we know, no better methods exist for diagnosing chondral lesions than arthroscopy and MRI. In our institution, we regard ankle arthroscopy and MRI as necessary tools for the diagnosis of chondral lesions. Therefore, in cases like those described in this report, an accurate diagnosis of OCL of the ankle requires the combined use of MRI for evaluating the subchondral conditions and ankle arthroscopy for evaluating the chondral conditions. Several reports have been published regarding the etiology of OCL of the ankle joint. Many investigators have concluded that OCL of the ankle is primarily traumatic in origin.1,2,4,6-16 Berndt and Harty1 reported that 21 of 24 patients had trauma-associated OCL of the ankle. They suggested that OCL of the ankle joint is almost always associated with an acute traumatic episode. Canale8 reported that all of the lateral lesions in the cohort studies were associated with trauma and 64% of patients with medial lesions had experienced a significant traumatic event. Van Dijk and Scholte16 reported that all lateral lesions are associated with traumatic episode, and 25% of the medial lesions are associated with trauma. Several authors2,4,6,7,9-17 have concurred with this theory, finding that lateral lesions are almost always associated with a traumatic episode while 25% to 80% of medial lesions are associated with trauma. However, whether OCL is usually initiated by a single acute trauma or develops gradually after recurrent ankle sprain remains to be clarified. In the current study, high rates of OCL were found at the time of osteosynthesis. This finding would seem to suggest that most cases of OCL in fractures occur at the time of initial trauma. Conversely, chronic lateral instability of the ankle had a higher rate of OCL than subacute cases. This result suggested that recurrent ankle sprain with remaining lateral instability is one cause of OCL in lateral instability of the ankle. In subacute lateral instability of the ankle, chondral lesions were more frequent than other types of lesions. Conversely, in chronic cases, osteochondral lesions were more frequent than other types. This result suggests that there is little damage to the cartilage and the subchondral bone in the initial injury. Rather, it is the remaining lateral instability that brings the more severe damage to the cartilage and subchondral bone. Regarding the location patterns of the OCL, Berndt
and Harty1 reported the OCL’s location when the anterolateral talar dome impacts the face of the fibula while the ankle is positioned in dorsiflexion and an inversion stress is applied to the joint. When the plantar flexed ankle is subjected to a combination of inversion force and external rotation of the ankle on the tibia, the posteromedial talar dome impacts the tibial articular surface, creating a posteromedial lesion. The current study suggests another mechanism that produces OCLs at the anterolateral or posteromedial parts of the talar dome is when the anterolateral talar dome impacts the face of the fibula while the ankle is positioned in supination and an external rotation stress is applied to the joint or the ankle is positioned in pronation and abduction stress is applied to the joint. An OCL also forms when the posteromedial talar dome impacts the tibial articular surface while the ankle is positioned in supination and an adduction or external rotation force is applied to the joint or the ankle is positioned in pronation and an abduction or external rotation stress is applied to the joint. In conclusion, a high percentage of OCL occurred at the time of initial trauma in distal fibular fractures. Among the cases of lateral instability of the ankle, a higher rate of OCL cases was found in chronic cases than in subacute cases. Our study suggests that recurrent ankle sprain with remaining lateral instability and distal fibular fractures could be one of the causes of OCL of the ankle. REFERENCES 1. Berndt AL, Harty M. Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 1959;41:9881020. 2. Anderson IF, Crichton KJ, Grattan-Smith T, et al. Osteochondral fractures of the dome of the talus. J Bone Joint Surg Am 1989;71:1143-1152. 3. De Smet AA, Fisher DR, Burnstein MI, et al. Value of MR imaging in staging osteochondral lesions of the talus (osteochondritis dissecans): Results in 14 patients. Am J Roentgenol 1990;154:555-558. 4. Pritsch M, Horoshovski H, Farine I. Arthroscopic treatment of osteochondral lesions of the talus. J Bone Joint Surg Am 1986;68:862-865. 5. Takao M, Ochi M, Naito K, et al. Arthroscopic drilling for chondral, subchondral, combined chondral-subchondral lesions of the talar dome. Arthroscopy 2003;19:524-530. 6. Alexander AH, Lichtman DM. Surgical treatment of transchondral talar-dome fractures (osteochondritis dissecans): Long term follow-up. J Bone Joint Surg Am 1980;62:646-652. 7. Baker CL, Andrews JR, Ryan JB. Arhtroscopic treatment of transchondral talar dome fractures. Arthroscopy 1986;2:82-87. 8. Canale ST, Belding RH. Osteochondral lesions of the talus. J Bone Joint Surg Am 1980;62:97-102. 9. Flick AB, Gould N. Osteochondritis dissecans of the talus (transchondral fractures of the talus): Review of the literature
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