Talocrural and Subtalar Joint Instability After Lateral Ankle Sprain
March 1, 2000 4 minutes read
Talocrural and Subtalar Joint Instability After Lateral Ankle Sprain
ABSTRACT & COMMENTARY
Synopsis: Recurrent lateral ankle sprains may be a result of combined talocrural and subtalar joint instability.
Source: Hertel J, et al. Talocrural and subtalar joint instability after lateral ankle sprain. Med Sci Sports Exerc 1999; 31(11):1501-1508.
Recurrent lateral ankle instability may represent injury to more than just the lateral ankle ligaments. Hertel and colleagues used stress fluoroscopy and physical examination to assess talocrural and subtalar joint instability in 12 subjects with a history of lateral ankle sprain (LAS) and eight healthy controls. For the fluoroscopic stress testing, four views of each ankle were taken: AP view in subtalar neutral, AP view with supination stress, lateral modified Broden view in subtalar neutral, and lateral modified Broden view with supination stress. For the lateral views, subjects were positioned sidelying for images of the subtalar joint. The physical examination included the anterior drawer (AD), talar tilt (TT), and medial subtalar glide (MSTG) tests. The AD and TT assess anterior displacement and excessive inversion of the talus within the ankle mortise, respectively. The MSTG tests for excessive medial translation of the calcaneus on the talus in the transverse plane. For the fluoroscopy and physical examinations, a four-point laxity scale was used to grade each ankle, where 0 represented no laxity, 1 mild laxity, 2 moderate laxity, and 3 gross laxity. Side-to-side laxity differences between the two groups were calculated for the AD, TT, MSTG physical examinations, and the AP and lateral fluoroscopy films. The imaging found greater talar tilt angles with supination stress in the injured ankles compared to the uninjured ankles, and 9/12 injured subjects had greater than 10° of talar tilt. Of these nine subjects, five had excessive subtalar laxity and an additional two had bilateral laxity of the posterior subtalar joint.
For all injured subjects, physical examination found greater laxity with the AD test but not with the TT or MSTG tests. Of the nine subjects with excessive talar tilt on imaging, the same seven had excessive laxity with the AD and MSTG tests, and six of these seven had laxity with the TT test. None of the three subjects who had less than 10° of talar tilt on imaging had excessive laxity on the subtalar stress views or the physical examination tests. These findings suggest a subpopulation of subjects with a history of lateral ankle sprain have combined talocrural and subtalar joint instability.
COMMENT BY DAVID H. PERRIN, PhD, ATC
Lateral ankle sprains are among the most frequent injuries experienced by competitive and recreational athletes, and recurrence occurs at a high rate in physically active individuals. Evaluation and treatment of LAS are typically directed to the lateral ligaments and talocrural joint of the ankle. This study reinforces the need to address stability of both the talocrural and subtalar joints. The primary challenge to Hertel et al and other authors would seem to be the difficulty in accurately assessing subtalar joint instability. The arthrokinematics of the joint include the triplanar motions of supination and pronation, and the literature seems inconclusive about the most accurate method of assessing laxity at the subtalar joint.
The advantage of the method used by Hertel et al is the ease with which it can be used clinically. Further research should explore the validity of this and other more sophisticated methods for assessing combined talocrural and subtalar joint instability. The design of this study does not determine if talocrural, subtalar, or combined talocrural/subtalar joint instability contributes to LAS. Future research should establish the extent to which increased laxity at the subtalar joint is a contributing factor to initial or recurrent LAS. The integrity of the talocrural and subtalar joints should be determined before conservative or surgical treatment is prescribed.
In the presence of combined laxity, surgical intervention should address the stability of both joints. Conservative measures can include the use of orthotics to control excessive motion of the subtalar joint. We’ve studied the effects of orthotics on acute lateral ankle sprains and found decreased postural sway with the use of a custom-fitted orthotic.1 Our subjects also subjectively reported feeling more "stable" with the wearing of an orthotic.
Further research should address the value of the ankle brace in providing similar support to the subtalar joint. A reduction in injury recurrence is the goal of conservative and surgical treatment of LAS. Clinicians must recognize the existence of subtalar joint instability in some patients with LAS and, in these cases, should direct treatment to stabilizing the talocrural and subtalar joints. As Hertel et al have pointed out, additional research is needed to refine procedures for diagnosis of laxity at the subtalar joint and to establish the efficacy of various conservative and surgical treatments in correction of subtalar joint instability.
Reference
1. Guskiewicz KM, Perrin DH. Effect of orthotics on postural sway following inversion ankle sprain. J Orthop Sports Phys Ther 1996;23:326-331.
Instability of the subtalar joint is assessed with which of the following physical examinations?
a. Anterior drawer test
b. Medial subtalar glide test
c. Talar tilt test tibiofibular compression test
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