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Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome
Journal of Orthopaedic Science xxx (2017) 1e6
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome Tomoyuki Nakasa*, Mikiya Sawa, Yasunari Ikuta, Masahiro Yoshikawa, Yusuke Tsuyuguchi, Nobuo Adachi Department of Orthopaedic Surgery, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi Minamiku Hiroshima City, 734-8551, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 August 2017 Received in revised form 25 November 2017 Accepted 6 December 2017 Available online xxx
Background: Osteochondral lesions of the talus (OLT) are recognized as being commonly associated with trauma. However, the etiology of OLT remains unclear. In the case of a posteromedial lesion of OLT (medial OLT), the deep layer of the deltoid ligament is located close to the medial OLT, and this relationship between a medial lesion and deltoid ligament could be a risk factor for medial OLT. The purpose of this study is to investigate the unique anatomic feature of the deep deltoid attachment to the talus in patients with medial OLT compared with patients with non-medial OLT. Methods: Forty ankles with medial OLT and 40 ankles without medial OLT were retrospectively reviewed in this study. On the coronal images of MRI, the attachment of deltoid ligament was measured. The continuity of the osteochondral fragment and its bed was evaluated on MRI and arthroscopic findings. Results: Coronal MRI images showed that the attachment of the deep deltoid ligament to the medial OLT was broader and located more proximally than in non-medial OLT. The continuity of fibers from the insertion site of deltoid ligament to the talus to the osteochondral fragment was observed (76.7%). In the arthroscopic findings, the osteochondral fragment was obviously connected to the talus at the medial site in 85.2% of feet. Conclusions: The location of the deep deltoid ligament attachment to the medial OLT was more proximal and there was the possibility of these anatomic feature might contribute to the pathogenesis of medial OLT. © 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
1. Introduction Osteochondral lesions of the talus (OLT) are recognized as being commonly associated with ankle injuries such as sprains and fractures [1,2]. The incidence of OLT is increasing, especially in association with sports injuries [3,4]. Although trauma is the major cause of OLT, non-traumatic causes including congenital factors, embolic disease, and ligamentous laxity also play a role [5,6]. Elucidation of the etiology of OLT will enable exploration of the risk factors for OLT and to develop a novel approach for OLT treatment. Regarding the location of OLT, Flick et al. reported that 98% of lateral lesions and 70% of medial lesions were associated with a history of trauma [1]. Besides the prevalence of lateral versus medial lesions, there was a tendency of the morphological varieties
* Corresponding author. Fax: þ81 82 257 5234. E-mail address: [email protected] (T. Nakasa).
of lesions, for example an anterolateral lesion is a more shallow, wafer-shaped fragment, whereas a posteromedial lesion has a deeper, cup-shaped morphology [7]. The difference in the incidence and morphology of lesions might provide us with an insight into the medial OLT's unique mechanism. The etiology of osteochondritis dissecans (OCD) of the knee joint also remains unclear. As for OCD of the medial femoral condyle (MFC), the lesion is located close to the femoral attachment of the posterior cruciate ligament (PCL), and continuity of the PCL fibers to the osteochondral fragment can be seen. Ishikawa et al. demonstrated that the PCL in patients with OCD in the MFC is attached more distally at the lateral aspect of the MFC compared with OCD in the LFC and with ACL and meniscal injuries, which suggests that the PCL might exert an abnormal tensile force at the MFC to develop the osteochondral fragment [8]. In a medial OLT, the deep layer of the deltoid ligament is located close to the medial OLT, similar to the relationship between the PCL and medial OCD of the knee. The
https://doi.org/10.1016/j.jos.2017.12.001 0949-2658/© 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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T. Nakasa et al. / Journal of Orthopaedic Science xxx (2017) 1e6
deltoid ligament has the role of being a strong stabilizer, to restrict excessive eversion of the foot, and is composed of both superficial and deep layers [9,10]. Several cadaveric studies have proposed that the deltoid ligament is actually composed of 5e6 distinct bands with variations [11e13]. The variation of the band or talus attachment to the deep layer of the deltoid ligament might influence the development of the medial OLT by the repetitive traction stress, which leads to the hypothesis that the difference in the anatomic features of the deep deltoid ligament fibers could be a risk factor of the generation and progression for medial OLT. The purpose of this study is to investigate the unique anatomic feature of deep deltoid attachment in patients with medial OLT compared with patients with non-medial OLT.
weighed images were repetition time, 2000 ms; echo time, 20 ms; section thickness, 4.0 mm. The OCL was classified according to Anderson et al.'s grading system: 0, normal; 1, subchondral trabecular compression and marrow edema; 2, incomplete separation fragment; 2A, formation of a subchondral cyst; 3, unattached, nondisplaced fragment with synovial fluid surrounding it; 4, displaced fragment [14]. The lesion size and depth of OLT in stage 3 was defined on MRI findings, and the coronal length (horizontal extension on the coronal image), sagittal length (horizontal extension on the sagittal image), depth (vertical extension on the coronal image), and area (coronal length sagittal length) was measured according to the previous report [15]. 2.1. Deltoid ligament position index (DPI)
2. Material and methods This study was approved by the local ethical committee of our university. Forty ankles in 38 patients diagnosed with OLT between August 2009 and December 2016 met our inclusion criteria for this study. These patients consisted of 21 males and 17 females, with an average age of 28.3 years (range 12e70 years). Inclusion criteria comprised a radiological diagnosis of a medial OLT and no ligamentous instability. Osteochondral lesions were located at medial region of the talus confirmed by plain radiograms, CT and MRI. The ankle instability was confirmed using stress radiography. In these patients, 18 cases had the history of ankle sprain (45%). Forty ankles in 40 patients without medial OLT were also evaluated as the control group. Control group was selected as age matched for the medial OLT group. They consisted of 21 males and 19 females, with an average age of 24.7 years (range 12e50 years). The control group included 7 lateral OLTs, 2 OCLs in plafond, and 31 cases of lateral ankle pain and instability after ankle sprain. The patients with systemic diseases such as rheumatoid arthritis, a history of surgical treatment on the ankle, flat foot deformity or osteoarthritic change were excluded from this study. MRI scans were performed using a Signa 1.5-T device or a Signa HDxt 3.0-T device (GE Yokogawa Medical Systems Ltd.) with a wraparound surface coil designed for the ankle. Proton density SE and T2-weighed SE images were collected. The conditions for the T2 weighed images were repetition time, 2600 ms; echo time, 98 ms; section thickness, 4.0 mm. The conditions for proton
The coronal slice which described the attachment of deltoid ligament most widely among the serial slice was selected. To evaluate the attachment of the deltoid ligament to the talus on the coronal plane, the length of the deltoid ligament attachment to the talus was measured by drawing a line at the margin of the distal point of the talus deltoid ligament attachment and the most proximal margin of the talus deltoid ligament attachment which are parallel to the upper surface of talus (distance a). In addition, the distance between the articular margin of the talus and the most distal point of the talus deltoid ligament attachment was measured (distance b). Then, the deltoid position index (DPI) was produced from the ratio of a to b modified from the previous report (Fig. 1A) [8]. 2.2. Flexion angle (FA) Taking into consideration that the flexion angle (FA) of the ankle joint could affect the view of the coronal section and the measurement of the talus deltoid ligament attachment, the FA of the ankle joint was measured and compared between the sagittal sections of the groups. The lines along the talus and tibial shafts were drawn and its angle was measured (Fig. 1B). Thirty-seven of 40 feet underwent arthroscopic surgery for medial OLT by 2 surgeons (** and **). They were placed in a supine position, and standard anterolateral and anteromedial portals were established under joint distraction using an Ankle Distractor (Smith
Fig. 1. (A) Measurement of the deltoid ligament index (DPI). DPI was produced from the ratio of distance a to distance b. (B) Measurement of the flexion angle (FA) of the ankle joint (*).
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
T. Nakasa et al. / Journal of Orthopaedic Science xxx (2017) 1e6
& Nephew, Memphis, TN). A 2.7 mm 30 oblique arthroscope was used. During arthroscopic surgery, whether the osteochondral fragment was connected to the talus in the medial aspect was evaluated in stage 3 cases by probing the osteochondral fragment. Among the ankles which were converted arthroscopic to open surgery using medial malleolus osteotomy, biopsy from the junction of osteochondral fragment and deep deltoid ligament from two ankles. Paraffin embedded sections were prepared and histological analysis by HE staining was performed. 2.3. Statistical analysis All values are expressed as the mean ± standard deviation. The ManneWhitney U test was used to compare the DPI and FA values between the control and medial OLT groups. Two orthopaedic surgeons (** and **) performed the DPI and FA measurements in a randomized order, twice by each rater, with at least 30 days' duration between the measurements and their previous measurements. Then, intra-and interobserver reliabilities were analyzed using intraclass correlation coefficients (ICCs). The ICC values were interpreted as follows: <0.40, poor agreement; 0.40 < ICC <0.75, fair to good agreement; >0.75, excellent agreement. Spearman's correlation coefficients were used to explore the relationship between the size and depth of OLT and DPI. All statistical analysis was conducted using SSPI. Statistically significant differences were noted for p values < 0.05. 3. Results There were no significant age differences between the control and medial OLT groups (p ¼ 0.1366). The medial OLT group consisted of 10 stage 2A ankles and 30 stage 3 ankles according to Anderson's MRI grading. As for the FA, there was no significant difference between the control and medial OLT groups (control: 60.2 ± 2.9 : medial OLT: 60.2 ± 5.6 , p ¼ 0.4972), which enabled a comparison of the DPI between the control and medial OLT groups. The DPI in the medial OLT group was 71.3 ± 6.2% and that in the control group was 61.7 ± 5.7%. There was a significant difference between both groups (p < 0.05) (Fig. 2A). In comparison with stage 2A and 3 in the medial OLT group, the DPI at stage 3 (72.6 ± 5.5%)
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was larger than that at stage 2A (65.7 ± 5.2%), and there was a significant difference between both groups (p < 0.05) (Fig. 2B). In the coronal slice, the attachment of the deltoid ligament to the talus was a broad, fan-like shape in the medial OLT group, while that in the control was a straight insertion into the talus (Fig. 3AB). The attachment of the deltoid ligament to the talus at stage 2A in the medial OLT was also relatively broad compared to that in the nonmedial OLT, but its attachment was lower compared to that of stage 3 (Fig. 3C). This result suggested that proximal attachment of the deep deltoid ligament could have more influence on the OLT with the osteochondral fragment compared to that with the cystic lesion. The mean area of osteochondral fragment was 94.1 mm2 (ranged from 26.4 to 163.1 mm2), and the mean depth was 4.0 mm (ranged from 2.0 to 6.7 mm). There was no significant correlation between the depth and DPI (Spearman's rank correlation coefficient (rs) ¼ 0.0469, p ¼ 0.4027), while there was significant correlation between the size and DPI (rs ¼ 0.411, p ¼ 0.012). At stage 3, the continuity of the fibers from the insertion site of the talus to the osteochondral fragment was observed on MRI (23/30 ankles; 76.7%) (Fig. 3B). Twenty-seven of 30 ankles in stage 3 medial OCL underwent arthroscopic surgery. The arthroscopic findings clearly showed that the osteochondral fragment was connected to the talus at the medial site in 23 ankles (85.2%) (Fig. 4AB). In these patients, the gross appearance when medial malleolus osteotomy was performed showed that the osteochondral fragment fibers were continuous from the deep deltoid ligament (Fig. 4C). In the biopsy specimen, ligament tissue in the synovitis including angiogenesis was observed (Fig. 4D). Intra- and interobserver reliability in measuring DPI and FA was analyzed. For DPI, both intraobserver ICCs were excellent (0.91; 95% CI, 0.86e0.94), and interobserver ICCs were excellent (0.89; 95% CI, 0.83e0.93). For FA, intraobserver ICCs were excellent (0.91; 95% CI, 0.86e0.94), whereas interobserver ICCs were fair to good (0.73; 95% CI, 0.57e0.83). 4. Discussion Although the etiology of OLT has not been completely elucidated, a traumatic cause is widely accepted as the initiation factor of OLT [14,16]. In particular, the altered subchondral bone condition
Fig. 2. (A) The DPI of the medial OLT (med OLT) and non-medial OLT (control). (B) The DPI at stage 2A and 3 in the medial OLT.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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Fig. 3. (A) A representative case of non-medial OLT on MRI. (B) A representative case of a medial OLT at stage 3 on MRI. The arrows indicate the continuity of the osteochondral fragment with its bed. (C) A representative case of medial OLT at stage 2A on MRI.
is important for the progression of OLT. It is reported that microfractures in the subchondral bone plate and subchondral bone allow liquid to flow into the cartilage and subchondral bone, and continuous high fluid pressure causes osteolysis. After the fluid
pressure into the subchondral bone ceases, sclerotic change occurs around the lytic area. Impaired spontaneous healing of subchondral bone may be caused by intermittent fluid flow at every step around the osteochondral fragment [17]. OLTs occur commonly in the
Fig. 4. (A) Arthroscopic findings of stage 3 from the anteromedial portal view. (B) Arthroscopic findings from the anterolateral portal view. (C) Gross appearance of the osteochondral fragment and deep deltoid ligament when medial malleolus osteotomy performed. The continuity of the osteochondral fragment with the deltoid ligament was confirmed (Arrow). (D) Biopsy specimens from the junction of osteochondral fragment stained by hematoxylin & eosin. Ligament tissue was observed in the synovium. Bar indicates 200 mm.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
T. Nakasa et al. / Journal of Orthopaedic Science xxx (2017) 1e6
anterolateral and posteromedial talar dome, and stage 3 lesions are more likely to be located in the medial region [6,18]. Region-specific anatomical factors might contribute to the preclusion of spontaneous subchondral bone healing in the pathogenesis of OLT. Ishikawa et al. demonstrated a significantly distally located femoral PCL footprint in patients with MFC OCD compared with those with non-MFC OCD lesions. Moreover, they reported that the location of the femoral footprint was significantly lower in the open physis group compared with that of the closed physis group in MFC OCD patients. They advocated the possible theory that a lower femoral PCL footprint, which is associated with skeletal immaturity, induces excessive stress on the MFC and could be a risk factor for MFC OCD patients [8]. This study suggests that the anatomical variation of ligament attachment might influence the osteochondral injury located around the ligament attachment by exerting abnormal force on the lesion. The present study has revealed that the attachment of the deep deltoid ligament fibers in stage 3 OLT patients was located more proximally than in non-medial OLT, and that the fibers continued all the way to the osteochondral fragment, which suggests that the traction force via the deep deltoid fibers to the posteromedial site of talar dome during ankle motion might induce the damage of the subchondral bone toward generation and progression of the osteochondral fragment. In addition, there was a moderate correlation between the size of OLT and DPI, which might indicate that more proximal attachment of the deep deltoid ligament could transfer greater force to the posteromedial talar dome in the broad area. These unique anatomic features might cause an excessive traction force on the posteromedial region of the talar dome in a medial direction, which might lead to the impaired healing of subchondral bone in an osteochondral fragment. The fact that abnormal deltoid ligament conditions such as ruptures along with the ankle fractures or degeneration with acquired flat foot deformity are often found in the daily clinical setting, has led to special recognition of the importance of the deltoid ligament's anatomy. The deltoid ligament is a strong and broad ligament that spans out from the medial malleolus towards the talus, calcaneus, and navicular bone. Boss et al. demonstrated that the deltoid ligament is composed of 5 different bands, 3 bands of which belong to the superficial layer, tibiospring, tibiocalcaneal, and superficial posterior tibiotalar ligaments, and 2 bands to the deep layer, the anterior deep tibiotalar ligament (ATTL) and posterior deep tibiotalar ligament (dPTTL) [11]. Panchani et al.’s study involving 33 cadaveric ankles showed that the dPTTL is found in all ankles, and that this band is the widest and thickest of all deltoid ligament bands [19]. They also found anatomic variations in the deep deltoid ligaments, deep to the tibiocalcaneal ligament (dTCL) and a superficial layer band located posterior to the sustentaculum tali. The attachment of dTCL on the talus was in the superomedial aspect of the talus between the ATTL and dPTLL. However, the function of these anatomical variations is still unclear. The deltoid ligament has the role of primary ankle stabilizer to restrain against valgus tilting as well as against anterior and lateral translation of the talus [20]. Specifically, the superficial layer protects against eversion of the hindfoot and the deep layer is the primary restraint to external rotation of the talus, stabilizing the ankle against planter flexion [21e23]. It is reported that a medial OLT was reproduced by planterflexing the ankle in combination with slight anterior displacement of the talus on the tibia, with inversion and internal rotation of the talus on the tibia [16,17]. Although the majority of ankle sprain are injuries of the lateral ankle ligaments, 5% involving the deltoid ligament of the ankle is estimated [24]. Moreover, the deep deltoid ligament transferred the most force during 57.2% of the stance phase during gait [25]. There is the possibility that proximal attachment of the deep deltoid ligament may induce OLT during stance phase of gait and enforcing planter flexion by trauma
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such as ankle sprain. According to these reports, the normal function of the deep deltoid ligament seems to protect against medial OLT development. The present study revealed that the broad and proximal attachment of the deep deltoid ligament could be one of the risk factor for medial OLT. Therefore, the force on the posteromedial talar dome from deltoid ligament could be altered by the anatomical variation of the deep deltoid ligament. There are some limitations to this study. Firstly, the number of patients is small. Secondly, there was no functional analysis to conclude that the location of the deep deltoid ligament fiber being close to the medial OLT was significant in the pathogenesis of medial OLT. Further analyses using the 3-dimensional finite element model and cadaveric model are required. Finally, intact ankle joints were not utilized as normal samples in the control group of this study, although there was a significant difference in the DPI between the medial OLT and non-medial OLT group. In further analysis, volunteers with intact ankle joints should be enrolled to obtain the mean value of the deltoid ligament attachment of the normal ankle joint on MRI. In conclusion, the attachment of the deep deltoid ligament in the medial OLT was broad and fan-like shape and located more proximally, and its fibers were continuous to the osteochondral fragment, compared to non-medial OLT. The fact that this anatomic feature is a potential risk factor for medial OLT will help us to explore the pathomechanism of medial OLT. Conflict of interest The authors declare that they have no conflict of interest. References [1] Flick AB, Gould N. Osteochondritis dissecans of the talus (transchondral fractures of the talus): review of the literature and new surgical approach for medial dome lesions. Foot Ankle 1985 Jan-Feb;5(4):165e85. [2] Hintermann B, Regazzoni P, Lampert C, Stutz G, Gӓchter A. Arthroscopic findings in acute fractures of the ankle. J Bone Joint Surg Br 2000 Apr;82B(3): 345e51. [3] Saxena A, Eakin C. Articular talar injuries in Athletes: results of microfracture and autologous bone graft. Am J Sports Med 2007 Oct;35(10):1680e7. [4] Tol JL, Struijs PA, Bossuyt PM, Verhagen RA, van Dijk CN. Treatment strategies in osteochondral defects of the talar dome: a systemic review. Foot Ankle Int 2000 Feb;21(2):119e26. [5] Davis MW. Bilateral talar osteochondritis dissecans with lax ankle ligaments: report of a case. J Bone joint Surg Am 1970 Jan;52A(1):168e70. [6] Gardiner TB. Osteochondritis dissecans in three members of one family. J Bone Joint Surg Br 1995 Feb;37-B(1):139e41. [7] Raikin SM, Elis I, Zoga AC, Morrison WB, Besser MP, Schweitzer ME. Osteochondral lesions of the talus: localization and morphologic data from 424 patients using a novel anatomical grid schema. Foot Ankle Int 2007 Feb;28(2): 154e61. [8] Ishikawa M, Adachi N, Yoshikawa M, Nakamae A, Nakasa T, Ikuta Y, Hayashi S, Deie M, Ochi M. Unique anatomic feature of the posterior cruciate ligament in knees associated with osteochondritis dissecans. Orthop J Sports Med 2016 May;4(5). 2325967116648138. € tzens V, van [9] Golano P, Vega J, de Leeuw PA, Malagelada F, Manzanares MC, Go Dijk CN. Anatomy of the ankle ligaments: a pictorial essay. Knee Surg Sports Traumatol Arthros 2010 May;18(5):557e69. [10] Harper MC. Deltoid ligament: an anatomical evaluation of function. Foot Ankle 1987 Aug;8(1):19e22. [11] Boss AP, Hintermann B. Anatomical study of the medial ankle ligament complex. Foot Ankle Int 2002 Jun;23(6):547e53. [12] Sarrafian SK. Anatomy of the foot and ankle. 3rd ed. Philadelphia, PA: J.B. Lippincott Williams and Wilkins; 2011. [13] Smith JT, Bluman EM. Update on stage Ⅳ acquired adult flatfoot disorder: when the deltoid ligament becomes dysfunctional. Foot Ankle Clin 2012 Jun;17(2):351e60. [14] Anderson BF, Crichton KJ, Grattan-Smith T, Cooper RA, Brazier D. Osteochondral fractures of the dome of the talus. J Bone Joint Surg Am 1989 Sep;71(8):1143e52. [15] Choi WJ, Park KK, Kim BS, Lee JW. Osteochondral lesion of the talus: is there a critical size for poor outcome? Am J Sports Med 2009 Oct;37(10):1974e80. [16] Berndt AL, Harty M. Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 1959 Sep;41A(6):988e1020.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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[17] van Dijk CN, Reilingh ML, Zengerink M, van Bergen CJ. Osteochondral defects in the ankle: why painful? Knee Surg Sports Traumatol Arthrosc 2010 May;18(5):570e80. [18] Justin D, Orr MD, Jason R, Dutton DO, Justin T, Fowler MD. Anatomic location and morphology of symptomatic operatively treated osteochondral lesions of the talus. Foot Ankle Int 2012 Dec;33(12):1051e7. [19] Panchani PN, Chappell TM, Moore GD, Tubbs RS, Shoja MM, Loukas M, Kozlowski PB, Khan KH, DiLandro AC, D'Antoni AV. Anatomic study of the deltoid ligament of the ankle. Foot Ankle Int 2014 Sep;35(9):916e21. [20] Michelson JD, Hamel AJ, Buczek FL, Sharkey NA. The effect of ankle injury on subtalar motion. Foot Ankle Int 2004 Sep;25(9):639e46. [21] Earll M, Wayne J, Brodrick C, Vokshoor A, Adelaar R. Contribution of the deltoid ligament to ankle joint contact characteristics: cadaver study. Foot Ankle Int 1996 Jun;17(6):317e24.
[22] Jelinek JA, Porter DA. Management of unstable ankle fractures and syndesmosis injuries in athletes. Foot Ankle Clin 2009 Jun;14(2):277e98. [23] Michelson JD, Waldman B. An axially loaded model of the ankle after pronation external rotation injury. Clin Orthop Relat Res 1996 Jul;328: 285e93. [24] Waterman BR, Belmont Jr PJ, Cameron KL, Svoboda SJ, Alitz CJ, Owens BD. Risk factors for syndesmotic and medial ankle sprain: role of sex, sport, and level of competition. Am J Sports Med 2011 May;39(5):992e8. [25] Haraguchi N, Arminger RS, Myerson MS, Campbell JT, Chao EYS. Prediction of three-dimensional contact stress and ligament tension in the ankle during stance determined from computational modeling. Foot Ankle Int 2009 Feb;30(2):177e85.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
Contents lists available at ScienceDirect
Journal of Orthopaedic Science journal homepage: http://www.elsevier.com/locate/jos
Original Article
Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome Tomoyuki Nakasa*, Mikiya Sawa, Yasunari Ikuta, Masahiro Yoshikawa, Yusuke Tsuyuguchi, Nobuo Adachi Department of Orthopaedic Surgery, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi Minamiku Hiroshima City, 734-8551, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 24 August 2017 Received in revised form 25 November 2017 Accepted 6 December 2017 Available online xxx
Background: Osteochondral lesions of the talus (OLT) are recognized as being commonly associated with trauma. However, the etiology of OLT remains unclear. In the case of a posteromedial lesion of OLT (medial OLT), the deep layer of the deltoid ligament is located close to the medial OLT, and this relationship between a medial lesion and deltoid ligament could be a risk factor for medial OLT. The purpose of this study is to investigate the unique anatomic feature of the deep deltoid attachment to the talus in patients with medial OLT compared with patients with non-medial OLT. Methods: Forty ankles with medial OLT and 40 ankles without medial OLT were retrospectively reviewed in this study. On the coronal images of MRI, the attachment of deltoid ligament was measured. The continuity of the osteochondral fragment and its bed was evaluated on MRI and arthroscopic findings. Results: Coronal MRI images showed that the attachment of the deep deltoid ligament to the medial OLT was broader and located more proximally than in non-medial OLT. The continuity of fibers from the insertion site of deltoid ligament to the talus to the osteochondral fragment was observed (76.7%). In the arthroscopic findings, the osteochondral fragment was obviously connected to the talus at the medial site in 85.2% of feet. Conclusions: The location of the deep deltoid ligament attachment to the medial OLT was more proximal and there was the possibility of these anatomic feature might contribute to the pathogenesis of medial OLT. © 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
1. Introduction Osteochondral lesions of the talus (OLT) are recognized as being commonly associated with ankle injuries such as sprains and fractures [1,2]. The incidence of OLT is increasing, especially in association with sports injuries [3,4]. Although trauma is the major cause of OLT, non-traumatic causes including congenital factors, embolic disease, and ligamentous laxity also play a role [5,6]. Elucidation of the etiology of OLT will enable exploration of the risk factors for OLT and to develop a novel approach for OLT treatment. Regarding the location of OLT, Flick et al. reported that 98% of lateral lesions and 70% of medial lesions were associated with a history of trauma [1]. Besides the prevalence of lateral versus medial lesions, there was a tendency of the morphological varieties
* Corresponding author. Fax: þ81 82 257 5234. E-mail address: [email protected] (T. Nakasa).
of lesions, for example an anterolateral lesion is a more shallow, wafer-shaped fragment, whereas a posteromedial lesion has a deeper, cup-shaped morphology [7]. The difference in the incidence and morphology of lesions might provide us with an insight into the medial OLT's unique mechanism. The etiology of osteochondritis dissecans (OCD) of the knee joint also remains unclear. As for OCD of the medial femoral condyle (MFC), the lesion is located close to the femoral attachment of the posterior cruciate ligament (PCL), and continuity of the PCL fibers to the osteochondral fragment can be seen. Ishikawa et al. demonstrated that the PCL in patients with OCD in the MFC is attached more distally at the lateral aspect of the MFC compared with OCD in the LFC and with ACL and meniscal injuries, which suggests that the PCL might exert an abnormal tensile force at the MFC to develop the osteochondral fragment [8]. In a medial OLT, the deep layer of the deltoid ligament is located close to the medial OLT, similar to the relationship between the PCL and medial OCD of the knee. The
https://doi.org/10.1016/j.jos.2017.12.001 0949-2658/© 2017 Published by Elsevier B.V. on behalf of The Japanese Orthopaedic Association.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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deltoid ligament has the role of being a strong stabilizer, to restrict excessive eversion of the foot, and is composed of both superficial and deep layers [9,10]. Several cadaveric studies have proposed that the deltoid ligament is actually composed of 5e6 distinct bands with variations [11e13]. The variation of the band or talus attachment to the deep layer of the deltoid ligament might influence the development of the medial OLT by the repetitive traction stress, which leads to the hypothesis that the difference in the anatomic features of the deep deltoid ligament fibers could be a risk factor of the generation and progression for medial OLT. The purpose of this study is to investigate the unique anatomic feature of deep deltoid attachment in patients with medial OLT compared with patients with non-medial OLT.
weighed images were repetition time, 2000 ms; echo time, 20 ms; section thickness, 4.0 mm. The OCL was classified according to Anderson et al.'s grading system: 0, normal; 1, subchondral trabecular compression and marrow edema; 2, incomplete separation fragment; 2A, formation of a subchondral cyst; 3, unattached, nondisplaced fragment with synovial fluid surrounding it; 4, displaced fragment [14]. The lesion size and depth of OLT in stage 3 was defined on MRI findings, and the coronal length (horizontal extension on the coronal image), sagittal length (horizontal extension on the sagittal image), depth (vertical extension on the coronal image), and area (coronal length sagittal length) was measured according to the previous report [15]. 2.1. Deltoid ligament position index (DPI)
2. Material and methods This study was approved by the local ethical committee of our university. Forty ankles in 38 patients diagnosed with OLT between August 2009 and December 2016 met our inclusion criteria for this study. These patients consisted of 21 males and 17 females, with an average age of 28.3 years (range 12e70 years). Inclusion criteria comprised a radiological diagnosis of a medial OLT and no ligamentous instability. Osteochondral lesions were located at medial region of the talus confirmed by plain radiograms, CT and MRI. The ankle instability was confirmed using stress radiography. In these patients, 18 cases had the history of ankle sprain (45%). Forty ankles in 40 patients without medial OLT were also evaluated as the control group. Control group was selected as age matched for the medial OLT group. They consisted of 21 males and 19 females, with an average age of 24.7 years (range 12e50 years). The control group included 7 lateral OLTs, 2 OCLs in plafond, and 31 cases of lateral ankle pain and instability after ankle sprain. The patients with systemic diseases such as rheumatoid arthritis, a history of surgical treatment on the ankle, flat foot deformity or osteoarthritic change were excluded from this study. MRI scans were performed using a Signa 1.5-T device or a Signa HDxt 3.0-T device (GE Yokogawa Medical Systems Ltd.) with a wraparound surface coil designed for the ankle. Proton density SE and T2-weighed SE images were collected. The conditions for the T2 weighed images were repetition time, 2600 ms; echo time, 98 ms; section thickness, 4.0 mm. The conditions for proton
The coronal slice which described the attachment of deltoid ligament most widely among the serial slice was selected. To evaluate the attachment of the deltoid ligament to the talus on the coronal plane, the length of the deltoid ligament attachment to the talus was measured by drawing a line at the margin of the distal point of the talus deltoid ligament attachment and the most proximal margin of the talus deltoid ligament attachment which are parallel to the upper surface of talus (distance a). In addition, the distance between the articular margin of the talus and the most distal point of the talus deltoid ligament attachment was measured (distance b). Then, the deltoid position index (DPI) was produced from the ratio of a to b modified from the previous report (Fig. 1A) [8]. 2.2. Flexion angle (FA) Taking into consideration that the flexion angle (FA) of the ankle joint could affect the view of the coronal section and the measurement of the talus deltoid ligament attachment, the FA of the ankle joint was measured and compared between the sagittal sections of the groups. The lines along the talus and tibial shafts were drawn and its angle was measured (Fig. 1B). Thirty-seven of 40 feet underwent arthroscopic surgery for medial OLT by 2 surgeons (** and **). They were placed in a supine position, and standard anterolateral and anteromedial portals were established under joint distraction using an Ankle Distractor (Smith
Fig. 1. (A) Measurement of the deltoid ligament index (DPI). DPI was produced from the ratio of distance a to distance b. (B) Measurement of the flexion angle (FA) of the ankle joint (*).
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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& Nephew, Memphis, TN). A 2.7 mm 30 oblique arthroscope was used. During arthroscopic surgery, whether the osteochondral fragment was connected to the talus in the medial aspect was evaluated in stage 3 cases by probing the osteochondral fragment. Among the ankles which were converted arthroscopic to open surgery using medial malleolus osteotomy, biopsy from the junction of osteochondral fragment and deep deltoid ligament from two ankles. Paraffin embedded sections were prepared and histological analysis by HE staining was performed. 2.3. Statistical analysis All values are expressed as the mean ± standard deviation. The ManneWhitney U test was used to compare the DPI and FA values between the control and medial OLT groups. Two orthopaedic surgeons (** and **) performed the DPI and FA measurements in a randomized order, twice by each rater, with at least 30 days' duration between the measurements and their previous measurements. Then, intra-and interobserver reliabilities were analyzed using intraclass correlation coefficients (ICCs). The ICC values were interpreted as follows: <0.40, poor agreement; 0.40 < ICC <0.75, fair to good agreement; >0.75, excellent agreement. Spearman's correlation coefficients were used to explore the relationship between the size and depth of OLT and DPI. All statistical analysis was conducted using SSPI. Statistically significant differences were noted for p values < 0.05. 3. Results There were no significant age differences between the control and medial OLT groups (p ¼ 0.1366). The medial OLT group consisted of 10 stage 2A ankles and 30 stage 3 ankles according to Anderson's MRI grading. As for the FA, there was no significant difference between the control and medial OLT groups (control: 60.2 ± 2.9 : medial OLT: 60.2 ± 5.6 , p ¼ 0.4972), which enabled a comparison of the DPI between the control and medial OLT groups. The DPI in the medial OLT group was 71.3 ± 6.2% and that in the control group was 61.7 ± 5.7%. There was a significant difference between both groups (p < 0.05) (Fig. 2A). In comparison with stage 2A and 3 in the medial OLT group, the DPI at stage 3 (72.6 ± 5.5%)
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was larger than that at stage 2A (65.7 ± 5.2%), and there was a significant difference between both groups (p < 0.05) (Fig. 2B). In the coronal slice, the attachment of the deltoid ligament to the talus was a broad, fan-like shape in the medial OLT group, while that in the control was a straight insertion into the talus (Fig. 3AB). The attachment of the deltoid ligament to the talus at stage 2A in the medial OLT was also relatively broad compared to that in the nonmedial OLT, but its attachment was lower compared to that of stage 3 (Fig. 3C). This result suggested that proximal attachment of the deep deltoid ligament could have more influence on the OLT with the osteochondral fragment compared to that with the cystic lesion. The mean area of osteochondral fragment was 94.1 mm2 (ranged from 26.4 to 163.1 mm2), and the mean depth was 4.0 mm (ranged from 2.0 to 6.7 mm). There was no significant correlation between the depth and DPI (Spearman's rank correlation coefficient (rs) ¼ 0.0469, p ¼ 0.4027), while there was significant correlation between the size and DPI (rs ¼ 0.411, p ¼ 0.012). At stage 3, the continuity of the fibers from the insertion site of the talus to the osteochondral fragment was observed on MRI (23/30 ankles; 76.7%) (Fig. 3B). Twenty-seven of 30 ankles in stage 3 medial OCL underwent arthroscopic surgery. The arthroscopic findings clearly showed that the osteochondral fragment was connected to the talus at the medial site in 23 ankles (85.2%) (Fig. 4AB). In these patients, the gross appearance when medial malleolus osteotomy was performed showed that the osteochondral fragment fibers were continuous from the deep deltoid ligament (Fig. 4C). In the biopsy specimen, ligament tissue in the synovitis including angiogenesis was observed (Fig. 4D). Intra- and interobserver reliability in measuring DPI and FA was analyzed. For DPI, both intraobserver ICCs were excellent (0.91; 95% CI, 0.86e0.94), and interobserver ICCs were excellent (0.89; 95% CI, 0.83e0.93). For FA, intraobserver ICCs were excellent (0.91; 95% CI, 0.86e0.94), whereas interobserver ICCs were fair to good (0.73; 95% CI, 0.57e0.83). 4. Discussion Although the etiology of OLT has not been completely elucidated, a traumatic cause is widely accepted as the initiation factor of OLT [14,16]. In particular, the altered subchondral bone condition
Fig. 2. (A) The DPI of the medial OLT (med OLT) and non-medial OLT (control). (B) The DPI at stage 2A and 3 in the medial OLT.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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Fig. 3. (A) A representative case of non-medial OLT on MRI. (B) A representative case of a medial OLT at stage 3 on MRI. The arrows indicate the continuity of the osteochondral fragment with its bed. (C) A representative case of medial OLT at stage 2A on MRI.
is important for the progression of OLT. It is reported that microfractures in the subchondral bone plate and subchondral bone allow liquid to flow into the cartilage and subchondral bone, and continuous high fluid pressure causes osteolysis. After the fluid
pressure into the subchondral bone ceases, sclerotic change occurs around the lytic area. Impaired spontaneous healing of subchondral bone may be caused by intermittent fluid flow at every step around the osteochondral fragment [17]. OLTs occur commonly in the
Fig. 4. (A) Arthroscopic findings of stage 3 from the anteromedial portal view. (B) Arthroscopic findings from the anterolateral portal view. (C) Gross appearance of the osteochondral fragment and deep deltoid ligament when medial malleolus osteotomy performed. The continuity of the osteochondral fragment with the deltoid ligament was confirmed (Arrow). (D) Biopsy specimens from the junction of osteochondral fragment stained by hematoxylin & eosin. Ligament tissue was observed in the synovium. Bar indicates 200 mm.
Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001
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anterolateral and posteromedial talar dome, and stage 3 lesions are more likely to be located in the medial region [6,18]. Region-specific anatomical factors might contribute to the preclusion of spontaneous subchondral bone healing in the pathogenesis of OLT. Ishikawa et al. demonstrated a significantly distally located femoral PCL footprint in patients with MFC OCD compared with those with non-MFC OCD lesions. Moreover, they reported that the location of the femoral footprint was significantly lower in the open physis group compared with that of the closed physis group in MFC OCD patients. They advocated the possible theory that a lower femoral PCL footprint, which is associated with skeletal immaturity, induces excessive stress on the MFC and could be a risk factor for MFC OCD patients [8]. This study suggests that the anatomical variation of ligament attachment might influence the osteochondral injury located around the ligament attachment by exerting abnormal force on the lesion. The present study has revealed that the attachment of the deep deltoid ligament fibers in stage 3 OLT patients was located more proximally than in non-medial OLT, and that the fibers continued all the way to the osteochondral fragment, which suggests that the traction force via the deep deltoid fibers to the posteromedial site of talar dome during ankle motion might induce the damage of the subchondral bone toward generation and progression of the osteochondral fragment. In addition, there was a moderate correlation between the size of OLT and DPI, which might indicate that more proximal attachment of the deep deltoid ligament could transfer greater force to the posteromedial talar dome in the broad area. These unique anatomic features might cause an excessive traction force on the posteromedial region of the talar dome in a medial direction, which might lead to the impaired healing of subchondral bone in an osteochondral fragment. The fact that abnormal deltoid ligament conditions such as ruptures along with the ankle fractures or degeneration with acquired flat foot deformity are often found in the daily clinical setting, has led to special recognition of the importance of the deltoid ligament's anatomy. The deltoid ligament is a strong and broad ligament that spans out from the medial malleolus towards the talus, calcaneus, and navicular bone. Boss et al. demonstrated that the deltoid ligament is composed of 5 different bands, 3 bands of which belong to the superficial layer, tibiospring, tibiocalcaneal, and superficial posterior tibiotalar ligaments, and 2 bands to the deep layer, the anterior deep tibiotalar ligament (ATTL) and posterior deep tibiotalar ligament (dPTTL) [11]. Panchani et al.’s study involving 33 cadaveric ankles showed that the dPTTL is found in all ankles, and that this band is the widest and thickest of all deltoid ligament bands [19]. They also found anatomic variations in the deep deltoid ligaments, deep to the tibiocalcaneal ligament (dTCL) and a superficial layer band located posterior to the sustentaculum tali. The attachment of dTCL on the talus was in the superomedial aspect of the talus between the ATTL and dPTLL. However, the function of these anatomical variations is still unclear. The deltoid ligament has the role of primary ankle stabilizer to restrain against valgus tilting as well as against anterior and lateral translation of the talus [20]. Specifically, the superficial layer protects against eversion of the hindfoot and the deep layer is the primary restraint to external rotation of the talus, stabilizing the ankle against planter flexion [21e23]. It is reported that a medial OLT was reproduced by planterflexing the ankle in combination with slight anterior displacement of the talus on the tibia, with inversion and internal rotation of the talus on the tibia [16,17]. Although the majority of ankle sprain are injuries of the lateral ankle ligaments, 5% involving the deltoid ligament of the ankle is estimated [24]. Moreover, the deep deltoid ligament transferred the most force during 57.2% of the stance phase during gait [25]. There is the possibility that proximal attachment of the deep deltoid ligament may induce OLT during stance phase of gait and enforcing planter flexion by trauma
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such as ankle sprain. According to these reports, the normal function of the deep deltoid ligament seems to protect against medial OLT development. The present study revealed that the broad and proximal attachment of the deep deltoid ligament could be one of the risk factor for medial OLT. Therefore, the force on the posteromedial talar dome from deltoid ligament could be altered by the anatomical variation of the deep deltoid ligament. There are some limitations to this study. Firstly, the number of patients is small. Secondly, there was no functional analysis to conclude that the location of the deep deltoid ligament fiber being close to the medial OLT was significant in the pathogenesis of medial OLT. Further analyses using the 3-dimensional finite element model and cadaveric model are required. Finally, intact ankle joints were not utilized as normal samples in the control group of this study, although there was a significant difference in the DPI between the medial OLT and non-medial OLT group. In further analysis, volunteers with intact ankle joints should be enrolled to obtain the mean value of the deltoid ligament attachment of the normal ankle joint on MRI. In conclusion, the attachment of the deep deltoid ligament in the medial OLT was broad and fan-like shape and located more proximally, and its fibers were continuous to the osteochondral fragment, compared to non-medial OLT. The fact that this anatomic feature is a potential risk factor for medial OLT will help us to explore the pathomechanism of medial OLT. Conflict of interest The authors declare that they have no conflict of interest. References [1] Flick AB, Gould N. Osteochondritis dissecans of the talus (transchondral fractures of the talus): review of the literature and new surgical approach for medial dome lesions. Foot Ankle 1985 Jan-Feb;5(4):165e85. [2] Hintermann B, Regazzoni P, Lampert C, Stutz G, Gӓchter A. Arthroscopic findings in acute fractures of the ankle. J Bone Joint Surg Br 2000 Apr;82B(3): 345e51. [3] Saxena A, Eakin C. Articular talar injuries in Athletes: results of microfracture and autologous bone graft. Am J Sports Med 2007 Oct;35(10):1680e7. [4] Tol JL, Struijs PA, Bossuyt PM, Verhagen RA, van Dijk CN. Treatment strategies in osteochondral defects of the talar dome: a systemic review. Foot Ankle Int 2000 Feb;21(2):119e26. [5] Davis MW. Bilateral talar osteochondritis dissecans with lax ankle ligaments: report of a case. J Bone joint Surg Am 1970 Jan;52A(1):168e70. [6] Gardiner TB. Osteochondritis dissecans in three members of one family. J Bone Joint Surg Br 1995 Feb;37-B(1):139e41. [7] Raikin SM, Elis I, Zoga AC, Morrison WB, Besser MP, Schweitzer ME. Osteochondral lesions of the talus: localization and morphologic data from 424 patients using a novel anatomical grid schema. Foot Ankle Int 2007 Feb;28(2): 154e61. [8] Ishikawa M, Adachi N, Yoshikawa M, Nakamae A, Nakasa T, Ikuta Y, Hayashi S, Deie M, Ochi M. Unique anatomic feature of the posterior cruciate ligament in knees associated with osteochondritis dissecans. Orthop J Sports Med 2016 May;4(5). 2325967116648138. € tzens V, van [9] Golano P, Vega J, de Leeuw PA, Malagelada F, Manzanares MC, Go Dijk CN. Anatomy of the ankle ligaments: a pictorial essay. Knee Surg Sports Traumatol Arthros 2010 May;18(5):557e69. [10] Harper MC. Deltoid ligament: an anatomical evaluation of function. Foot Ankle 1987 Aug;8(1):19e22. [11] Boss AP, Hintermann B. Anatomical study of the medial ankle ligament complex. Foot Ankle Int 2002 Jun;23(6):547e53. [12] Sarrafian SK. Anatomy of the foot and ankle. 3rd ed. Philadelphia, PA: J.B. Lippincott Williams and Wilkins; 2011. [13] Smith JT, Bluman EM. Update on stage Ⅳ acquired adult flatfoot disorder: when the deltoid ligament becomes dysfunctional. Foot Ankle Clin 2012 Jun;17(2):351e60. [14] Anderson BF, Crichton KJ, Grattan-Smith T, Cooper RA, Brazier D. Osteochondral fractures of the dome of the talus. J Bone Joint Surg Am 1989 Sep;71(8):1143e52. [15] Choi WJ, Park KK, Kim BS, Lee JW. Osteochondral lesion of the talus: is there a critical size for poor outcome? Am J Sports Med 2009 Oct;37(10):1974e80. [16] Berndt AL, Harty M. Transchondral fractures (osteochondritis dissecans) of the talus. J Bone Joint Surg Am 1959 Sep;41A(6):988e1020.
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Please cite this article in press as: Nakasa T, et al., Anatomic feature of deltoid ligament attachment in posteromedial osteochondral lesion of talar dome, Journal of Orthopaedic Science (2017), https://doi.org/10.1016/j.jos.2017.12.001