Defining Equinus Based on Literature

Patrick A. DeHeer, DPM, FACFAS

2/12/2016

When discussing any component of equinus, the starting point must be standardizing the definition. The lack of a standard definition has led to much confusion. Many of the proposed definitions in the literature are based solely on anecdotal evidence, until DiGiovanni et al provided an evidence-based answer to this long-standing question in their landmark article “Isolated Gastrocnemius Tightness.(1)” The study consisted of 34 symptomatic patients with a multitude of common foot or ankle pathologies and 34 control patients without any foot or ankle pathology. Not only did they examine ankle joint dorsiflexion in both groups with the knee extended and not extended, they also evaluated the accuracy of clinical evaluation with a goniometer compared to a validated ankle joint dorsiflexion method of measurement.

Clearly, the literature shows questionable reliability of measuring ankle joint dorsiflexion using a goniometer, but this study did provide some validation of the method most commonly employed by clinicians to assess equinus (2,3). Their conclusion stated, “We have selected < 5° of maximal ankle dorsiflexion with the knee in full extension as our definition because it allowed us to diagnose the problem in those who were at risk (symptomatic patients) with fairly good reproducibility (76%) and, more importantly, we were able to reliably avoid (in 94% of the cases) unnecessary treatment of those who were not at risk (asymptomatic people).” Regarding the reliability of using a goniometer to measure equinus clinically, they stated, “Clinical examination was demonstrated to be fairly reliable in identifying muscle tightness.”

References:

  1. DiGiovanni, Christopher W., et al. “Isolated gastrocnemius tightness.” The Journal of Bone & Joint Surgery 84.6 (2002): 962-970.
  2. Lundgren, P., et al. “Invasive in vivo measurement of rear-, mid-and fore- foot motion during walking.” Gait & pos- ture 28.1 (2008): 93-100.
  3. Evans, Angela M., and Sheila D. Scutter. “Sagittal plane range of motion of the pediatric ankle joint: a reliability study.” Journal of the American Podiatric Medical Association 96.5 (2006): 418-422.

 



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