How To Diagnose Lateral Ankle Injuries

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Continuing Education Course #135 — October 2005

I am pleased to introduce the latest article, “How To Diagnose Lateral Ankle Injuries,” in our CE series. This series, brought to you by the North American Center for Continuing Medical Education (NACCME), consists of regular CE activities that qualify for one continuing education contact hour (.1 CEU). Readers will not be required to pay a processing fee for this course.

Diagnosing a lateral ankle injury can be challenging. The initial presentation may be deceptive and some injuries may require more advanced imaging to confirm an accurate diagnosis. Addressing these and other key points, Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM, provide a comprehensive guide to these common injuries that range from chronic lateral ankle instability to peroneal tendon injuries.

At the end of this article, you’ll find a 10-question exam. Please mark your responses on the enclosed postcard and return it to NACCME. This course will be posted on Podiatry Today’s Web site (www.podiatrytoday.com) roughly one month after the publication date. I hope this CE series contributes to your clinical skills.

Sincerely,

Jeff A. Hall
Executive Editor
Podiatry Today

INSTRUCTIONS: Physicians may receive one continuing education contact hour (.1 CEU) by reading the article on pg. 66 and successfully answering the questions on pg. 74. Use the enclosed card provided to submit your answers or log on to www.podiatrytoday.com and respond via fax to (610) 560-0502.
ACCREDITATION: NACCME is approved by the Council on Podiatric Medical Education as a sponsor of continuing education in podiatric medicine.
DESIGNATION: This activity is approved for 1 continuing education contact hour or .1 CEU.
DISCLOSURE POLICY: All faculty participating in Continuing Education programs sponsored by NACCME are expected to disclose to the audience any real or apparent conflicts of interest related to the content of their presentation.
DISCLOSURE STATEMENTS: Drs. Ardizzone and Valmassy have disclosed that they have no significant financial relationship with any organization that could be perceived as a real or apparent conflict of interest in the context of the subject of their presentation.
GRADING: Answers to the CE exam will be graded by NACCME. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam.
TARGET AUDIENCE: Podiatrists.
RELEASE DATE: October 2005.
EXPIRATION DATE: October 31, 2006.
LEARNING OBJECTIVES: At the conclusion of this activity, participants should be able to:
• differentiate among grade 1, grade 2 and grade 3 injuries to the lateral collateral ligaments;
• discuss common physical examination findings with chronic lateral ankle instability;
• assess findings from talar tilt and anterior drawer tests;
• discuss contributing factors to peroneal tendon injuries; and
• assess the potential benefits of orthotics as an adjunctive treatment for lateral ankle sprains.

Sponsored by the North American Center for Continuing Medical Education.

Here one can see an acute ankle injury. Once one has ruled out a fracture, acute or chronic lateral ankle injuries represent a diagnostic challenge.
This manual talar tilt/inversion stress radiograph shows excessive talar inversion within the ankle mortise. Note the intraarticular loose body in the lateral gutter.
This manual anterior drawer stress radiograph demonstrates incompetence of the anterior talofibular ligament.
Here one can see a peroneal tenogram showing extensive stenosing tenosynovitis and adhesions.
On this T1-weighted MRI image, one can see a partial tear to the anterior talofibular ligament and a shallow fibular groove.
Here is an extensive talar osteochondral defect on a T1-weighted MRI sequence.
Here one can see a compensated rigid forefoot valgus with an inverted calcaneus.
74
Author(s): 
By Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM

   Additional contributing factors may attenuate the superior peroneal retinaculum. These factors include an anomalous tendon or low-lying peroneal muscle belly.27 This condition constrains the peroneal tendon within the fibular groove, leading to mechanical attrition of the peroneus brevis tendon against the sharp posterior ridge of the fibula.8,26,28,29

   Many of these subtle injuries heal uneventfully. Occasionally, however, the patient will complain of persistent pain posterior to the lateral malleolus that is exacerbated by lateral cutting maneuvers such as the swift side-to-side motion one frequently sees in tennis or soccer, or abrupt changes in direction that occur when pivoting on one foot. Swelling may or may not be present but one may frequently reproduce pain via palpation of the tendons posterior to the lateral malleolus and through resisted ankle eversion.

   Frequently, clinicians may see evidence of a tear on a MRI as indicated by a C-shaped appearance to the tendon on an axial projection with abundant scar tissue formation surrounding the tendon and increased fluid signal on T2 STIR sequences.28,30,31,32 Magnetic resonance imaging may also help distinguish between a discrete tendon tear and less serious conditions of tendonitis or tendonosis although chronic tendonosis may be a precursor to an actual tear.30 Comparing T1 and T2 images at the distal tip of the fibula will help clarify potential “false positive” findings due to the magic angle phenomenon.28,31 Bear in mind that a normal study does not preclude surgical intervention under appropriate clinical circumstances.

   However, one cannot appreciate peroneal tenosynovitis on MRI. In order to diagnose this condition, which involves hypertrophic synovium within the peroneal tendon sheath within the tendons themselves, one should use a tenogram.33 When the tenogram is positive, the flow of radioopaque dye will be impeded by adhesion or stricture of the sheath or scar tissue about the tendon.34 Additionally, a tenogram may be potentially therapeutic as well as diagnostic. The mixture of local anesthetic and radioopaque dye into the closed space of the tendon sheath acts as a “balloon” to separate the adherent scar tissue from the surface of the tendon. Adding corticosteroid into the injection may potentially “shrink” any adhesive scar tissue and decrease inflammation. Given the risk of tendon rupture with corticosteroid injection to tendons, this procedure requires a skilled radiologist to ensure an injection into the space between the tendon sheath and the actual tendon itself.

   Subluxation of the peroneal tendons may occur for anatomical reasons or as a result of an inversion injury but the subluxation is often overshadowed by a lateral collateral ligament injury.35 During an inversion injury and particularly following repeated ankle sprains, the peroneal retinaculum may be stretched and no longer retain the tendons posterior to the lateral malleolus.26,27 If the patient has an anatomically shallow fibular groove, then even a subtle injury to the retinaculum may cause the tendons to slide anteriorly.34,36 Recent studies also suggest that a more posterior anatomic position of the fibula may also contribute to instability, influencing the ability of the peroneal tendons to stabilize the ankle.37

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