Background: Contracture of the gastrocnemius-soleus complex has well-documented deleterious effects on lower-limb function in spastic or neurologically impaired individuals. There is scarce literature, however, on the existence of isolated gastrocnemius contracture or its impact in otherwise normal patients. We hypothesized that an inability to dorsiflex the ankle due to equinus contracture leads to increased pain in the forefoot and/or midfoot and therefore a population with such pain will have less maximum ankle dorsiflexion than controls. We further postulated that the difference would be present whether the knee was extended or flexed.
Methods: This investigation was a prospective comparison of maximal ankle dorsiflexion, as a proxy for gastrocnemius tension, in response to a load applied to the undersurface of the foot in two healthy age, weight, and sex-matched groups. The patient group comprised thirty-four consecutive patients with a diagnosis of metatarsalgia or related midfoot and/or forefoot symptoms. The control group consisted of thirty-four individuals without foot or ankle symptoms. The participants were clinically examined for gastrocnemius and soleus contracture and were subsequently assessed for tightness with use of a specially designed electrogoniometer. Measurements were made both with the knee extended (the gastrocnemius under tension) and with the knee flexed (the gastrocnemius relaxed).
Results: With the knee fully extended, the average maximal ankle dorsiflexion was 4.5 degrees in the patient group and 13.1 degrees in the control group (p < 0.001). With the knee flexed 90 degrees, the average was 17.9 degrees in the patient group and 22.3 degrees in the control population (p = 0.09). When gastrocnemius contracture was defined as dorsiflexion of < or = 5 degrees during knee extension, it was identified in 65% of the patients compared with 24% of the control population. However, when gastrocnemius contracture was defined as dorsiflexion of < or = 10 degrees, it was present in 88% and 44%, respectively. When gastrocnemius-soleus contracture was defined as dorsiflexion of < or = 10 degrees with the knee in 90 degrees of flexion, it was identified in 29% of the patient group and 15% of the control group.
Conclusions: On the average, patients with forefoot and/or midfoot symptoms had less maximum ankle dorsiflexion with the knee extended than did a control population without foot or ankle symptoms. When the knee was flexed 90 degrees to relax the gastrocnemius, this difference was no longer present.
Clinical relevance: These findings support the existence of isolated gastrocnemius contracture in the development of forefoot and/or midfoot pathology in otherwise healthy people. These data may have implications for preventative and therapeutic care of patients with chronic foot problems.