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Dislocation, Ankle
Updated: Apr 22, 2009
Introduction
Background
Ankle dislocations occur when significant force applied to the joint results in loss of opposition of the articular surfaces. Because of the large amount of force required and the inherent stability of the joint, dislocation of the ankle joint is rarely seen without an associated fracture.
Pathophysiology
The ankle joint is designed for a balance of stability and flexibility, particularly the former. Joint stability is provided by close articulation of the talus with the tibia and fibula. The mortise design further enhances the stability of the configuration.
The talus is trapezoidal in shape, with the greater width anteriorly. As the joint moves into plantar flexion, the talus becomes narrower, resulting in a decrease in stability. During normal walking, the ankle joint bears 3-5 times the body weight. This factor increases several fold during running and jumping activities. As weight is applied on heel strike, the fibula descends to increase stability of the ankle joint.
Mortality/Morbidity
- Associated fractures are the rule rather than the exception with ankle dislocations.
- Ligamentous disruption varies according to the type of dislocation. (See Ankle Injury, Soft Tissue.)
- Neurovascular injury is the principal concern, as with any dislocation. Vascular compromise may result in avascular necrosis of the talus if not promptly reduced. Tented skin may be subject to ischemic necrosis.
Sex
- Dislocations of the ankle are seen more frequently in young males than in any other group. This presumably is related to their increased risk overall for traumatic injury.
- Postmenopausal women are at higher risk for associated fractures. Increased fracture risk probably is related to osteoporotic changes in this subset of patients.
Age
Children and adolescents have the most ankle dislocations.
Clinical
History
A detailed history regarding the mechanism of injury often helps predict the type of injuries to expect. Furthermore, an understanding of the injury mechanism aids treatment, since an opposite force is required in reduction of the joint. Four types of dislocations are seen around the ankle joint.
- Posterior
- A posterior dislocation in the most common type of ankle dislocation. The talus moves in a posterior direction in relation to the distal tibia as force drives the foot backward. The wider anterior talus wedges back, resulting in forced widening of the joint.
- This must be accompanied by either a disruption if the tibiofibular syndesmosis or a fracture if the lateral malleolus. This occurs most commonly when the ankle is plantar flexed.
- Anterior
- Anterior dislocations result from the foot being forced anteriorly at the ankle joint.
- Typically, this occurs with the foot fixed and a posterior force applied to the tibia or with forced dorsiflexion.
- Lateral
- These dislocations result from forced inversion, eversion, or external or internal rotation of the ankle.
- They are associated uniformly with fractures of either or both the malleoli or the distal fibula.
- Superior
- Diastasis occurs when a force drives the talus upward into the mortise. These dislocations usually are the result of a fall from a height.
- In such cases, the patient should be evaluated carefully for concomitant spine injury and fracture of the calcaneus.
Physical
- Inspection of the ankle reveals significant edema with deformity ranging from trace to obvious. Tenting of the skin by the malleoli may be noted.
- Palpation of the joint reveals tenderness along the joint line, corresponding to areas of capsular or ligamentous disruption.
- In associated fractures, tenderness, deformity, or tenting proximal to the joint may be seen.
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References
Daffner RH. Ankle trauma. Semin Roentgenol. Apr 1994;29(2):134-51. [Medline].
Daffner RH. Ankle trauma. Radiol Clin North Am. Mar 1990;28(2):395-421. [Medline].
Distefano S, Divita G. A case of pure dislocation of the ankle joint. Ital J Orthop Traumatol. Mar 1988;14(1):133-7. [Medline].
Finkemeier C, Engebretsen L, Gannon J. Tibial-talar dislocation without fracture: treatment principles and outcome. Knee Surg Sports Traumatol Arthrosc. 1995;3(1):47-9. [Medline].
Graeme KA, Jackimczyk KC. The extremities and spine. Emerg Med Clin North Am. May 1997;15(2):365-79. [Medline].
Greenbaum MA, Pupp GR. Ankle dislocation without fracture: an unusual case report. J Foot Surg. May-Jun 1992;31(3):238-40. [Medline].
Griffiths HJ. Trauma to the ankle and foot. Crit Rev Diagn Imaging. 1986;26(1):45-105. [Medline].
Krishnamurthy S, Schultz RJ. Pure posteromedial dislocation of the ankle joint. A case report. Clin Orthop Relat Res. Dec 1985;(201):68-70. [Medline].
Merianos P, Papagiannakos K, Hatzis A, Tsafantakis E. Peritalar dislocation: a follow-up report of 21 cases. Injury. Nov 1988;19(6):439-42. [Medline].
Moehring HD, Tan RT, Marder RA, Lian G. Ankle dislocation. J Orthop Trauma. 1994;8(2):167-72. [Medline].
Mooney JF, Naylor PT, Poehling GG. Anterolateral ankle dislocation without fracture. South Med J. Feb 1991;84(2):244-7. [Medline].
Schuberth JM. Diagnosis of ankle injuries: the essentials. J Foot Ankle Surg. Mar-Apr 1994;33(2):214. [Medline].
Wilson AB, Toriello EA. Lateral rotatory dislocation of the ankle without fracture. J Orthop Trauma. 1991;5(1):93-5. [Medline].
Wroble RR, Nepola JV, Malvitz TA. Ankle dislocation without fracture. Foot Ankle. Oct 1988;9(2):64-74. [Medline].
Further Reading
Keywords
ankle dislocation, ankle joint, dislocated ankle, ankle injuries, ankle fracture, ankle sprain, sprained ankle, broken ankle, tibia, fibula, talus, ankle bones, posterior ankle dislocation, anterior ankle dislocation, superior ankle dislocation, lateral ankle dislocation, dislocation of the ankle, dislocation of the ankle joint
