I’ve been discussing the need for a standard definition to apply to equinus conditions. I believe the condition is under diagnosed because of the vast variety of opinions about just what qualifies as equinus.

Last week, I covered research that I felt was based on low numbers which can lead to the opposite situation — over diagnosis. (Equinus | Intelligent Management No. 2 in a Series)

Referring to an article by J.F. Grady and A. Saxena; Effects of stretching the gastrocnemius muscle, in J. Foot Surg 30: 465, 1991 — a uniblind examination of ankle joint dorsiflexion with various times of stretching exercises performed once a day for six months:

  • 30 seconds
  • 2 minutes
  • 5 minutes

The study used found the average pre-stretching measurements of the 25 participants to be 2.86+/-2.99 degrees of dorsiflexion with the knee extended and 9.02+/-2.35 degrees of ankle joint dorsiflexion with the knee flexed. Their study showed no statistical significance to the improved ankle joint dorsiflexion to recommend manual stretching.

The key point for this discussion is the pre-treatment numbers. The patients were measured with a goniometer in subtaler neutral with the midtarsal joint locked. This number is similar to Hill’s definition of 3-degrees as mentioned in the last post entitled Equinus | Intelligent Management No. 2 in a Series. Again, I think this is slightly off toward the low end.

C.W. Digiovanni, R. Kuo, N. Tejwani, et al wrote Isolated gastrocnemius tightness, in J Bone Joint Surg Am 84; 962, 2002, which examined the frequency of equinus in a symptomatic patient group and control group; and the reliability of clinical evaluation of equinus compared to an equinometer (this would be a computer measurement of ankle joint dorsiflexion). They used two definitions of equinus — 5-degrees and 10-degrees ankle joint dorsiflexion with the knee extended.

In the symptomatic group, the average ankle joint dorsiflexion with the knee extended was 4.5-degrees. In the control group, it was 13.1-degrees. The 5-degree group contained 65% symptomatic patients and 24% control group patients. In the 10-degree group, there were 88% symptomatic patients and 44% were of the control group.

The reliability of clinical exam compared to the equinometer for the 5-degree group was 76% for the symptomatic group of patients and 94% for the patients in the control group. For the 10-degree group, the reliability was 88% for the symptomatic group and 79% for the control group. The following quote from their article summarizes their findings.

“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).”

When examining this literature, it is clear to me that the standard definition of equinus should be 5-degrees of ankle-foot dorsiflexion with the knee extended. It is important to have the subtaler joint in neutral postion and the midtarsal joint locked.

Readers who are experienced with foot conditions will be more familiar with some of the terms than patients or people who have foot pain but who haven’t found someone who can offer relief. If you have questions about your condition, I recommend that you contact a professional with your questions and seek a professional evaluation. As this post reports, standard definition and professional evaluation can both deliver adequate treatment and/or avoid over-treatment.