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

   Patients will often complain of sudden sharp pain to the lateral ankle with lateral cutting maneuvers, pivoting or rising onto the balls of the feet.34 Swelling may or may not be present. Often, during the physical exam, the physician can feel the tendons snap or slide anterior to the fibula by palpating the area while the patient either rotates the foot in a circular motion or rises onto the balls of the feet. One may not appreciate subtle sliding of the tendons on examination. Obtaining a MRI can aid in diagnosis since it will show evidence of stretching or scarring of the peroneal retinaculum as well as decreased concavity of the peroneal groove.6,7,26,28-30

Recognizing Potential Nerve Injuries

   Nerve injuries are often the last category of injury clinicians consider when diagnosing lateral ankle problems. Nerve symptoms may include pain, burning, tingling or numbness. The symptoms will often radiate distally or proximally. The symptoms may or may not be related to activity but will often relate to the position of the foot or pressure from shoes.38

   Any inversion injury has the potential to place traction on the sural nerve as it runs alongside the peroneal tendons. Additionally, the superficial peroneal nerve becomes superficial in close proximity to the anterior talofibular ligament and may become partially entrapped in scar tissue as injury to the ligament heals. Blunt trauma may cause direct injury to the nerve itself, resulting in neuropraxia.

   Patients may complain of sharp pain with sudden pivoting movement or any compression of the anterior of the lateral ankle, which may occur in high-topped boots or ski boots.39 Other complaints may consist of either transient or constant numbness, and periodic tingling or burning sensations. Symptoms may be worse at night than during the day. More serious injuries, such as plantarflexion inversion injuries, may result in traction injury to either the sural or common peroneal nerves, leading to axonotemesis or neurotemesis, depending on the severity. Specifically, plantarflexion inversion injury causes constriction of the peroneus longus at the level of the common peroneal nerve, entrapping the nerve as it passes underneath the muscle.

   Physical exam findings may indicate allodynia, decreased sensation to light touch, an inability to distinguish between sharp and dull stimuli and decreased two-point stimulation. Manual percussion of the affected nerve precipitates distal paresthesias (positive Tinel’s sign) or more infrequently proximal paresthesias (positive Valleix’s sign).5,40 Swelling about the affected area is rarely present. Severe injuries of the common peroneal nerve may cause paralysis and muscle atrophy, leading to foot drop.5,41

   More sophisticated diagnostic studies are often necessary, particularly when it comes to distinguishing between local nerve injury and a possible correlation to any associated or past low back injury. One should suspect radiculopathy in any patient who exhibits positive proximal findings, particularly in a positive straight leg raise test. Electrodiagnostic studies, including nerve conduction studies, may be key in ruling out radiculopathy or mononeuropathy in these patients.5,39

What You Should Know About Intraarticular Injuries

   In the lateral ankle, intraarticular injuries typically consist of impingement syndromes, chondral and osteochondral lesions. Chondral lesions involve only the articular cartilage while osteochondral lesions consist of injury to the cartilage and the underlying bone.42 Occasionally, a talar dome lesion may be visible on initial X-ray following an inversion injury or a patient may have a loose body present from a prior injury that appears on a X-ray. However, these injuries frequently do not manifest until later in the healing process or once the patient returns to regular activity.

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