How To Diagnose Lateral Ankle Injuries

Author(s): 
By Remy Ardizzone, DPM, and Ronald L. Valmassy, DPM

Assessing The Potential Impact Of Orthotic Solutions

   Given that a significant percentage of chronic lateral ankle problems is associated with either a flexible or rigid forefoot valgus deformity, functional foot orthoses offer an effective adjunct to the overall management of this condition.    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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