Magnetic resonance imaging evaluation of lateral ankle ligaments and peroneal tendons in a group of asymptomatic patients

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1 Magnetic resonance imaging evaluation of lateral ankle ligaments and peroneal tendons in a group of asymptomatic patients Abstract: Background: The role of magnetic resonance (MR) imaging in patients with lateral ankle instability remains unclear. This study reports the MR findings in patients with asymptomatic ankles.materials and Methods: A total of 14 ankles in 11 asymptomatic patients were evaluated using 3.0 Tesla MR scanners. Imaging planes included axial PD and T2 weighted sequences, coronal fatsaturated PD fast spin sequence, sagittal T1 weighted sequence, and sagittal STIR sequence. Two musculoskeletal radiologists reviewed all images to reach consensus about abnormal findings.results: A total of 7/14 (50%) of subjects demonstrated abnormal anterior talofibular ligament (ATFL), 8/14 (57%) demonstrated abnormal calcaneofibular ligament (CFL), and 2/14 (14%) demonstrated abnormal posterior talofibular ligament (PTFL). In addition, 9/14 (64%) subjects were noted to have peroneal tendon pathology.conclusion: This study demonstrates that MR abnormalities in the lateral ligament complex and peroneal tendons can frequently be present in asymptomatic subjects. Keywords: ankle instability. peroneal tendonitis, ligament injury, MR imaging, ankle sprain Introduction Ankle sprains are one of the most common musculoskeletal injuries, comprising over 25% of all sports related trauma. 1-4 Of the 23,000 ankle injuries that occur each day in the United States, up to 85% involve the lateral ligaments. 3-4 Although most patients fully recover with non-surgical treatment and physical rehabilitation, symptomatic chronic instability is found in 10% to 40% of patients. 5-8 The high incidence and potential for long-term functional limitation reinforces the importance of accurate diagnosis and treatment of lateral ankle instability. This study reports magnetic resonance (MR) imaging findings in a group of asymptomatic volunteers. The current diagnostic procedure for ankle injury includes performing a thorough history and physical examination, with subsequent imaging to evaluate for ligamentous injury and fractures. 1 Stress radiographs are effective in the mechanical assessment of lateral stability. However, patients with

2 functional ankle instability, partial ligamentous tear or ligament degeneration with continuity may exhibit negative stress radiographs. As a result, with its superior soft tissue contrast resolution, multiplanar capability, and ability to show intra-articular or extra-articular sources of ankle pain, MR imaging has emerged as the imaging modality of choice in diagnosing and/or confirming ligamentous injuries of the ankle Despite its widespread use, MR evaluation of chronic lateral ankle instability has limitations. While the conventional MR findings of an abnormal lateral collateral ligament (LCL) complex have been well described, studies have shown that the sensitivity of preoperatively detecting lesions using MR imaging in patients with chronic ankle instability by a radiologist and orthopaedic surgeon is 45% and 63%, respectively. 12 In addition, there is very little data regarding the incidence of MR findings in an asymptomatic population. The current study is designed to evaluate the MR findings of the lateral ankle ligament complex and peroneal tendons in an asymptomatic group of patients in order to evaluate the role of MR evaluation in the diagnosis of lateral ankle instability. Methods Patient Selection A total of 14 ankles in 11 asymptomatic healthy volunteers (4 female, 7 male, age range of years, mean age of 35 years) were evaluated with MR imaging. Subjects were asked to complete a questionnaire to determine the likelihood of a known previous ankle injury and to rule out the possibility of current ankle instability. The questionnaire also provided information about the subject s history of activitylimiting ankle injury and subsequent treatment if any, in addition to past and current activity level. Inclusion criteria specified subjects who were currently asymptomatic in regards to ankle pain and/or instability, and subjects who reported consistent aerobic activity, as determined by the questionnaire. Exclusion criteria were limited to subjects with current ankle pain or prior history of ankle instability. 3/14 ankles (21%) had previous injury that limited physical activity, and all were treated conservatively with none of the subjects having ongoing symptoms.

3 MR evaluation of the LCL complex and peroneal tendons in this group was accomplished using a 3.0 Tesla MR scanner (Verio, Siemens). Imaging planes included axial PD and T2 weighted sequence, a coronal fat-saturated PD fast spin sequence, a sagittal T1 weighted sequence, and a sagittal STIR sequence. All subjects in this study provided written consent and the project met the standards for IRB approval. MR Interpretation Two musculoskeletal radiologists reviewed all images independently, and consensus about abnormal findings was made during conference. LCL complex abnormalities considered abnormal included thickening, thinning, morphologic irregularity, disruption, or absence of any ligamentous structure. Peroneal tendon abnormality was defined by the presence of tendinosis, tearing, tenosynovial fluid, subuluxation or dislocation, or superior peroneal retinaculum tear. Source of Funding There was no source of funding for this study. Results In total, there were 8/14 (57%) of ankles that had at least one abnormality of the LCL complex found on MRI. Table 1 summarizes the LCL complex findings. Anterior Talofibular Ligament There were 7/14 (50%) of subjects that were found to have an abnormal ATFL. This included 3 that were thickened, 3 that were thinned, and one that was found to have a morphologic irregularity independent of thickening or thinning. Of note, all 7 patients with an abnormal ATFL had a concomitant abnormal CFL. Examples of a normal AFTL, thinned ATFL, and thickened ATFL are shown in Figures 1, 2, and 3, respectively.

4 Calcaneofibular Ligament A total of 8/14 (57%) of subjects demonstrated an abnormal CFL. These were all noted to be thickening of the CFL. Of these patients, 7 of the 8 (88%) with an abnormal CFL also had an abnormal ATFL. Normal and thickened-appearing CFL examples are shown in Figures 4 and 5, respectively. Posterior Talofibular Ligament An abnormal posterior talofibular ligament was observed in 2/14 (14%) of subjects. The PTFL abnormality identified in both subject was a morphologically irregular ligament. The subjects with an abnormal PTFL also had an abnormal ATFL and CFL. A normal and irregular PTFL are shown in Figure 6 and 7, respectively. Peroneal Tendon Pathology There were 9/14 (64%) subjects that displayed peroneal tendon pathology. This included 7 with tendinosis and 2 with peroneal brevis split tears (independent of tendinosis). These two groups were further subdivided based on the presence of abnormal tenosynovial fluid. A total of 7/9 (78%) of the subjects with peroneal tendon pathology also had an abnormal LCL complex. Figures 8 shows a subject with tendinosis of the peroneal brevis tendon. Conclusions Lateral ankle sprains are one of the most common musculoskeletal injuries. The high incidence and potential for long-term functional limitation with lateral ankle instability continue to fuel research on its prevention, diagnosis, and treatment. This study demonstrates that MR abnormalities in the lateral ankle ligament complex and peroneal tendons can be present in subjects that do not have symptoms of chronic lateral ankle instability. The morphological abnormalities visualized by MR evaluation in the subjects in this study included a high incidence both thickening and thinning of the ankle ligaments as well as peroneal tendinosis and split tears. These findings reinforce the importance of clinical judgment in the diagnosis of lateral ankle instability and suggest that MR imaging should be used as a guide to treatment only in the appropriate clinical setting.

5 Lateral ankle instability (LAI) has been defined as an ankle rendered unstable following disruption of the lateral ligaments. When symptoms of instability persist for greater than six months it is considered chronic ankle instability. LAI may be secondary to either mechanical (supraphysiologic range of motion) or functional (subjective) instability; however, it is often a combination of the two. Patients with LAI experience recurrent ankle sprains, difficulty walking on uneven surfaces, and a sensation that the ankle is giving way. Current diagnostic procedure for ankle injury includes performing a thorough history and physical examination, including the anterior drawer and talar tilt tests, with subsequent imaging to evaluate for ligamentous injury and fractures. 13 Stress radiographs are effective in the mechanical assessment of lateral stability but patients with functional ankle instability, partial ligamentous tear or ligament deterioration with continuity may exhibit negative stress radiographs. Magnetic resonance imaging of the ankle is playing an increasingly important role in the diagnosis of chronic ankle instability and the planning for surgical treatment. 12 Hua and colleagues illustrated the efficacy of MR imaging in ankle ligament evaluation by confirming that the anatomy and the CT and MR images correlated well. 11 It was also found that the optimal position for MR imaging of the lateral ligaments is the natural resting position of the ankle (20 degrees tarsal flexion). Increased ligament thickness measured through transverse MR imaging was seen in acute ankle sprains, suggesting the utility of this modality in the clinical diagnosis of lateral ligament injury. Bauer et al. found that MR imaging at 3.0 Tesla (T) was superior to 1.5 T in the visualization of cartilage pathology and had a higher sensitivity for detecting ligament lesions in fresh cadaver ankles. The accuracy of ligament pathology grading was also twice as high at 3.0 T than at 1.5 T. 10 Potential limitations of MR imaging are illustrated in an article by Takao et al., which suggests arthroscopy is more sensitive in detecting ligamentous injury than MR imaging. In 14 patients with functional ankle instability, arthroscopic examination revealed morphologic ATFL abnormalities in all patients, whereas three of the ankles appeared to be normal in MR imaging evaluation. 14 Studies have also

6 shown that the sensitivity of preoperatively detecting lesions using MR imaging in patients with chronic ankle instability by a radiologist and orthopaedic surgeon is 45% and 63%, respectively. 12 In another study by Chandnani et al, the sensitivity of diagnosing an ATFL and CFL tear proved to be only 50% for both ligaments. 15 Despite the thickness of the ATFL and CFL on MR imaging being used to aid in the diagnosis of ligamentous injury, a recent study found no statistically significant difference in thickness between those with and without known ankle injury. 16 Furthermore, ankle pathology may be difficult to confirm because of the presence of anatomical variants. Lateral ligament pathology is also commonly associated with extra-articular conditions. In a retrospective review of 180 ankles following modified Brostrom procedure for LAI, Strauss et al. found that 64% of patients had an associated condition, most commonly peroneal tendon injuries (28%), os trigonum lesions (13%), lateral gutter ossicles (10%), and hindfoot varus alignment (8%). 17 There is limited information on the specificity and sensitivity of MR imaging for the diagnosis of these associated ankle disorders. The current study demonstrates that both lateral ligament and peroneal tendon pathology can be present on MR imaging in patients without symptoms of lateral ankle instability. Limitations of this study include the small number of subjects in this asymptomatic group of patients. Additional subjects across a broader age range would provide a more accurate portrayal of the prevalence of MR imaging abnormalities. In addition, it remains difficult to determine which abnormalities are examples of remote injuries or normal variations. Despite these limitations, this study identified a wide array of ankle lateral ligament and peroneal tendon abnormalities in an asymptomatic group of patients. Individuals can demonstrate abnormalities in the static and dynamic stabilizers of the lateral ankle as evident by MR imaging, yet remain clinically asymptomatic. The findings in this study suggest that clinical judgment should remain the key component in the diagnosis of lateral ankle instability with MR imaging serving to guide treatment in appropriate clinical settings.

7 Tables: Table 1. Summary of abnormal ankle magnetic resonance (MR) findings in a group of asymptomatic patients. Asymptomatic Volunteers Abnormal ATFL 7/14 (50%) Thickened partial tear (1) Thinned partial tear (1) Absent 0 a Morphologic irregularity 1 Abnormal CFL 8/14 b (57%) Thickened 8 Thinned 0 Absent 0 a Morphologic irregularity 0 Abnormal PTFL 2/14 (14%) Thickened 0 Thinned 0 absent 0 a,d Morphologic irregularity 2 Total number of Ankles with an LCL Complex Abnormality Peroneal Tendon Pathology 8/14 (57%) 9/14 f (64%) Tendinosis 7 peroneal brevis split tears (2) abnormal tenosynovial fluid (2) e Peroneal Brevis Split Tears 2 abnormal tenosynovial fluid (1) Abnormal Tenosynovial 0 Fluid Figure Legend:

8 Figure 1. Normal-appearing anterior talofibular ligament (ATFL) in 35 year-old male subject. Figure 2. Thinning of the ATFL in a 35 year-old female subject. Figure 3. Thickened appearance of the ATFL in a 29 year-old male subject.

9 Figure 4. Normal-appearing calcaneofibular ligament (CFL) in a 35 year-old female subject. Figure 5. Thickened-appearing CFL in a 35 year-old female subject.

10 Figure 6. Normal-appearing posterior talofibular ligament (PTFL) in a 33 year-old male subject. Figure 7. Irregular morphology of the PTFL in 47 year-old male subject.

11 Figure 8. Tendinosis of the peroneal brevis tendon in a 42 year-old male subject References 1. Balduini FC, Vegso JJ, Torg JS, Torg E. Management and rehabilitation of ligamentous injuries to the ankle. Sports Med. Sep-Oct 1987;4(5): Brostrom L. Sprained ankles. 3. Clinical observations in recent ligament ruptures. Acta Chir Scand. Dec 1965;130(6):

12 3. Kannus P, Renstrom P. Treatment for acute tears of the lateral ligaments of the ankle. Operation, cast, or early controlled mobilization. J Bone Joint Surg Am. Feb 1991;73(2): Karlsson J, Sancone M. Management of acute ligament injuries of the ankle. Foot Ankle Clin. Sep 2006;11(3): Hupperets MD, Verhagen EA, Heymans MW, Bosmans JE, van Tulder MW, van Mechelen W. Potential savings of a program to prevent ankle sprain recurrence: economic evaluation of a randomized controlled trial. Am J Sports Med. Nov 2010;38(11): Hupperets MD, Verhagen EA, van Mechelen W. Effect of unsupervised home based proprioceptive training on recurrences of ankle sprain: randomised controlled trial. BMJ. 2009;339:b van Rijn RM, van Os AG, Bernsen RM, Luijsterburg PA, Koes BW, Bierma-Zeinstra SM. What is the clinical course of acute ankle sprains? A systematic literature review. Am J Med. Apr 2008;121(4): e van Rijn RM, van Os AG, Kleinrensink GJ, et al. Supervised exercises for adults with acute lateral ankle sprain: a randomised controlled trial. Br J Gen Pract. Oct 2007;57(543): Barr C, Bauer JS, Malfair D, et al. MR imaging of the ankle at 3 Tesla and 1.5 Tesla: protocol optimization and application to cartilage, ligament and tendon pathology in cadaver specimens. Eur Radiol. Jun 2007;17(6): Bauer JS, Barr C, Henning TD, et al. Magnetic resonance imaging of the ankle at 3.0 Tesla and 1.5 Tesla in human cadaver specimens with artificially created lesions of cartilage and ligaments. Invest Radiol. Sep 2008;43(9): Hua J, Xu JR, Gu HY, et al. Comparative study of the anatomy, CT and MR images of the lateral collateral ligaments of the ankle joint. Surg Radiol Anat. Jun 2008;30(4): O'Neill PJ, Van Aman SE, Guyton GP. Is MRI adequate to detect lesions in patients with ankle instability? Clin Orthop Relat Res. Apr 2010;468(4): Haraguchi N, Toga H, Shiba N, Kato F. Avulsion fracture of the lateral ankle ligament complex in severe inversion injury: incidence and clinical outcome. Am J Sports Med. Jul 2007;35(7): Takao M, Innami K, Matsushita T, Uchio Y, Ochi M. Arthroscopic and magnetic resonance image appearance and reconstruction of the anterior talofibular ligament in cases of apparent functional ankle instability. Am J Sports Med. Aug 2008;36(8): Chandnani VP, Harper MT, Ficke JR, et al. Chronic ankle instability: evaluation with MR arthrography, MR imaging, and stress radiography. Radiology. Jul 1994;192(1): Dimmick S, Kennedy D, Daunt N. Evaluation of thickness and appearance of anterior talofibular and calcaneofibular ligaments in normal versus abnormal ankles with MRI. J Med Imaging Radiat Oncol. Dec 2008;52(6): Strauss JE, Forsberg JA, Lippert FG, 3rd. Chronic lateral ankle instability and associated conditions: a rationale for treatment. Foot Ankle Int. Oct 2007;28(10):

V E R I TAS MGH 1811 MGH 1811 V E R I TAS. *Gerber JP. Persistent disability with ankle sprains. Foot Ankle Int 19: , 1998.

V E R I TAS MGH 1811 MGH 1811 V E R I TAS. *Gerber JP. Persistent disability with ankle sprains. Foot Ankle Int 19: , 1998. MGH 1811 Management of Ankle Instability Richard J. de Asla, M.D. V E R I TAS MGH 1811 I have no potential conflicts with this presentation. V E R I TAS It s just a sprain Lateral Ankle Sprains Most common