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Alex Brenner PT MPT OCS -> Re: Chronic ankle pain (June 27, 2005 8:42:00 PM)
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[image]http://img.photobucket.com/albums/v85/brennerak/AnkleStressViewLedit.jpg[/image]
[image]http://img.photobucket.com/albums/v85/brennerak/AnkleStressViewRedit.jpg[/image]
This is a talar tilt stress view radiograph comparing the symptomatic side (right) to the asymptomatic side (left) on this 24 year old female soldier.
The true stress radiologic criteria for diagnosing mechanical lateral ankle instability are controversial. Normal talar tilt values have been reported to range from 0° to 23° (1,2). Because of the wide variance of normal values, some authors feel that this test is not a reliable indicator of ankle instability (2). Others argue that anteroposterior and lateral stress views do not take into account the rotational instability that is occurring at the ankle and subtalar joint (3). This may explain the complaints of subjective ankle instability in the face of normal radiographic stress tests ("functional instability"). One study (4) demonstrated that a 10° difference in talar tilt between the injured and uninjured ankle was diagnostic of a sprain of both lateral ankle ligaments in 97% of cases. Most authors agree that a difference of 5° to 15° between the injured and uninjured side is diagnostic of mechanical ankle instability (5).
1. Rubin G, Witten M: The talar tilt angle and the fibular collateral ligaments: a method for the determination of talar tilt. J Bone Joint Surg 1960;42A:311-326
2. Seligson D, Gassman J, Pope M: Ankle instability: evaluation of the lateral ankle ligaments. Am J Sports Med 1980;8(1):39-42
3. Hintermann B: Biomechanics of the unstable ankle joint and clinical implications. Med Sci Sports Exerc 1999;31(7 Suppl):S459-S469
4. Chrisman OD, Snook GA: Reconstruction of lateral ligament tears of the ankle: an experimental study and clinical evaluation of seven patients treated by a new modification of the Elmslie procedure. J Bone Joint Surg Am 1969;51(5):904-912
5. Safran MR, Benedetti RS, Bartolozzi AR 3rd, et al: Lateral ankle sprains: a comprehensive review. Part 1: etilology, pathoanatomy, histopathogenesis, and diagnosis. Med Sci Sports Exerc 1999;31(7 Suppl):S429-S437
This particular patient had a difference of 17 degrees left to right. The measured angle is formed by drawing a straight line across the tibial plafond and a line across the dome of the talus. From my conversations with an orthopaedic surgeon the gold standard for ankle instability is arthroscopy. I personally feel in order to fully diagnose true ankle instability versus something like ligament laxity or someone with just poor proprioception there needs to be the “total package”. Meaning that the patient should have several findings including; 1) patient history consistent with ankle instabililty, i.e. trauma or mechanism of injury and history of chronic ankle sprains 2) physical exam consistent with ankle instability. Positive talar tilt and anterior drawers when compared to healthy side 3) Ankle stress views showing the differences compared to healthy side as shown in studies listed above.
On a side note, from what I read the patient should undergo some sort of local anesthetic in the ankle before performing the talar tilt stress view so that you will not get any muscle guarding during the x-ray procedure. I have never seen this done.
Follow on question. What surgeries are performed to correct ankle instability?
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