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Physical Exam of Sub Talar Joint

- Discussion:
    - wt bearing line of the body normally falls medial to the axis of sub talar joint, & therefore, when the patient stands on one foot, the  foot pronates;
           - when pt rotates leg externally, heel inverts & wt bearing line moves laterally;
    - total arc of motion of this joint is about 20 deg;
    - most accurate method of measuring degree of sub talar motion is to place pt prone & flex his knee to approx 135 deg;
           - axis of sub talar joint now lies close to horizontal plane;
           - examiner then passively inverts & everts heel while he measures extent of motion by atching a gravity goniotomer, or level, to calcaneus, using a metal strip clip;
    - subtalar neutral position:
           - the foot position when the subtalar, talonavicular and calacneocuboid joints are reduced and congruous;
           - clinically, the foot is placed in the neutral position by centering the navicular on the talus;
           - after the foot has been placed in the neutral position, it is possible to determine the relative varus/valgus of the hindfoot and forefoot;

- Testing Eversion and Inversion of Subtalar Joint:
    - functionally, range of motion of the subtalar joint can be measured by viewing the standing patient from behind (heel eversion) and then by having the patient stand up on the ball of the foot (heel inversion);
    - inversion:
           - when the pt raises on his heels, the heel will promptly invert, longitudinal arch will rise, and the leg will rotate externally if his foot is function normally;
           - since inversion of the heel is achieved thru proper performance of the subtalar and transverse tarsal joints, failure to invert the heel needs to be evaluated;
           - ability of the heel to invert adequately determines the effectiveness of foot to fulfill its role as a rigid lever at time of push off;
    - eversion:
           - note that relaxed one legged standing alignment gives a good indication of maximum heel vaglus;

- Standing Coleman Block Test

- Hindfoot Valgus:
    - see: pes valgus in CP
    - w/ significant hindfoot valgus look for sinus tarsi pain cause by impingement of the fibula on the calcaneus;

- Hind Foot Varus:
    - more common in cavus feet (cavovarus feet);
    - pts w/ cavus feet are typically more symptomatic than pts w/ pes planus;
          - in latter pts, transverse tarsal joint is unlocked, & therefore, foot can adapt easily to saggital & horizontal plane stresses;
    - it is because of this rigidity that foot is unable to fine tune or compensate for minor stress;
    - if hindfoot varus occurs in childhood, 1st metatarsal is plantar flexed by peroneus longus, causing an extremely rigid cavus foot

Biomechanics and Orthotics of the Foot in Athletes.

Assessment of rearfoot motion: passive positioning, one legged standing, gait.