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

   When functional foot orthoses address the lateral column instability of the foot (by supporting the everted forefoot position via intrinsic or extrinsic forefoot posting), patients experience dramatic improvement with regard to their lateral instability. This is particularly true in the case of rigid forefoot valgus deformity, in which the foot functions with an inverted rearfoot from heel contact through the propulsive phase of gait. Additionally, a flexible forefoot valgus foot type that compensates via supination of the longitudinal axis of the midtarsal joint will also benefit via lateral stabilization. Even individuals who pronate excessively demonstrate an improvement of their lateral instability when they utilize a functional forefoot orthosis as the locking mechanism of the midfoot and midtarsal joint is allowed to function in a more appropriate fashion.19,51

   However, there are some cases in which inverting the foot may exacerbate some cases of lateral ankle instability. In these cases, it is appropriate to pronate the foot maximally during the casting procedure and introduce an iatrogenic forefoot valgus deformity. One may then instruct the orthotics laboratory to correct the valgus deformity with the patient stabilized in this pronated position. Clinicians should then consider the presence of a limb length inequality as contributing to lateral ankle instability. A shortened limb may often function in a more supinated or inverted fashion in an attempt to equalize leg length. In these cases, employing a heel lift with or without a functional foot orthosis may prove successful in increasing stability.52,53

A Guide To Differential Diagnosis Of Lateral Ankle Injuries

   Lateral collateral ligament sprain
   Syndesmosis sprain (high ankle sprain)
   Lateral malleolar fracture
   Lateral talar process fracture
   Anterior process calcaneus fracture
   Subtalar injury
   Fifth metatarsal base fracture
   Peroneal tendon injury
   Osteochondral injury
   Peroneal nerve injury
   Sural nerve injury
   Calcaneocuboid injury
   Intraarticular loose body/impingement

Key Contributing Factors To Inversion Ankle Injuries

   Ligamentous laxity
   Ankle varus
   Tibial varum
   Forefoot valgus
   Uncompensated equinus
   Rigid plantarflexed first ray
   Peroneal muscle weakness
   Limb length discrepancy
   Supinated subtalar joint
   Prior inversion ankle injury

In Conclusion

   Many different lateral ankle injuries may have similar presentations and more subtle injuries may be overshadowed by the initial acute trauma. Ensuring a thorough understanding of the acute and functional aspects of lateral ankle injuries will allow practitioners to provide effective and efficient care for patients presenting with these injuries.

Dr. Ardizzone is a Staff Podiatrist at the Center for Sports Medicine at St. Francis Memorial Hospital in San Francisco, Calif. She is an Associate of the American College of Foot and Ankle Surgeons.

Dr. Valmassy is a Staff Podiatrist at the Center for Sports Medicine at St. Francis Memorial Hospital in San Francisco, Calif. He is a Fellow of the American College of Foot and Ankle Orthopedics and Medicine. Dr. Valmassy is also a Diplomate of the American Board of Podiatric Orthopedics and Primary Podiatric Medicine.

For related articles, see “How To Manage Lateral Ankle Sprains In Athletes” in the November 2003 issue or “Revisiting A Proven Approach To Severe Ankle Instability” in the November 2004 issue of Podiatry Today. Also be sure to visit the archives at www.podiatrytoday.com.




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