Ankle dorsiflexion: what is normal? Development of a decision pathway for diagnosing impaired ankle dorsiflexion and M. gastrocnemius tightness.

Abstract

Impaired ankle dorsiflexion (ADF) is known to increase forefoot pressure, which is associated to various pathologies affecting the foot and ankle. M. gastrocnemius tightness (MGT) is its most common cause. Up to date we are missing a standardized examination procedure, norm values, and a valid decision pathway to diagnose impaired ADF and MGT. The aim of this study was to define norm values for ADF using a standardized examination procedure. These were used to define a decision pathway to diagnose impaired ADF and MGT. 64 young, asymptomatic subjects were examined. Based on a standardized examination procedure, bilateral ADF, both with the knee extended and flexed, non-weight bearing and weight bearing, was assessed by three investigators. Inter-rater test reliability and norm values for ADF were calculated. Side differences were analyzed. ADF differences between the knee extended and flexed were calculated. The standardized examination procedure revealed high ICC values (0.876-0.915). ADF values with the knee extended for the left/right limb were 22.7°±5.9° [95% CI 21.2°-24.3°]/23.4°±6.5° [95% CI 21.7°-25.1°] non-weight bearing and 33.3°±5.5° [95% CI 31.9°-34.7°]/33.6°±5.6° [95% CI 32.1°-35.0°] weight bearing. Physiological side differences with the knee extended were <6° (95% CI). Knee flexion resulted in an approximate ADF increase of 10°. Based on an extensive systematic approach, physiological values for ADF were assessed in a large asymptomatic population. This allowed the definition ofa decision pathway to diagnose impaired ADF and MGT. Patients presenting with pathologies associated with impaired ADF should be examined according to the herein presented examination protocol. This systematic approach provides a consistent definition of impaired ADF and MGT, which is the prerequisite to study the effectiveness of treatment strategies for MGT.