By Paul Glass and Justin Yerkes
Postural Examination[1]
A thorough postural examination of the Subtalar (Talocalcanean) Joint involves the assessment of the patient in standing, sitting, and prone positions. The examiner should view the joint from the anterior, posterior, and lateral prospectives. Assessment of the joints above and below that influence the kinematic chain and ultimately the position of the subtalar joint should also be considered.
The examiner should take a look at the position of the patient's leg. It has been shown that medial rotation of the leg causes a valgus (outward) movement of the calcaneus, whereas lateral rotation of the leg produces a varus (inward) movement of the calcaneus.
Image available at:
http://www.pt.ntu.edu.tw/hmchai/Kinesiology/KINlower/Foot.files/FootKinematics.htm
Supination and pronation are tri-planar movements that occur at the subtalar joint due to its oblique axis. With the motion that occurs between the talus, calcaneus and forefoot in different situations, you need to consider more than just open and closed chain positions, but you must also be aware of whether the talus is mobile or stable and whether the forefoot is mobile or stable. The following motions occur at the calcaneus, the talus and the forefoot in the given situations:
Supination
Closed Chain (talus mobile): Calcaneus inverts, Talus dorsiflexes and abducts, Forefoot is stable
Closed Chain (talus stable): Calcaneus inverts, Talus is stable, Forefoot plantarflexes and adducts
Pronation
Open Chain (talus mobile): Calcaneus everts, Talus plantarflexes and adducts, Forefoot is stable
Open Chain (talus stable): Calcaneus everts, Talus stable, Forefoot dorsiflexes and abducts
Click here for more detail on motion of the subtalar joint
In Standing[1]
Anterior View: Observe position of patient's hips, trunk, and medial longitudinal arch of the foot.
Hip and trunk lateral rotation away from the opposite hip will elevate the medial longitudinal arch, whereas medial rotation of the hip or trunk will tend to flatten the arch.
Supination: Check for calcaneal inversion with midfoot and forefoot pronation to maintain contact with the floor. This will manifest as an accentuated medial longitudinal arch.
Pronation: Check for calcaneal eversion with midfoot and forefoot supination to maintain contact with the floor. This will manifest as a depressed medial longitudinal arch.
Posterior View: Check the alignment of the calcaneus and achilles tendon.
Supination: Calcaneal varum AKA calcaneal inversion results in movement of the talus into abduction and dorsiflexion relative to the calcaneus. As a result of the transverse motion of abduction by the talus the leg follows with external rotation. Also, talar dorsiflexion in the sagittal plane creates slight motion at the knee into extension.
Pronation: Calcaneal valgum AKA calcaneal eversion results in movement of the talus into adduction and plantarflexion relative to the calcaneus. As the talus moves in the transverse plane into adduction the leg follows resulting in internal rotation. Also, as the talus plantarflexes it moves the knee into slight flexion.
- Deviation of the achilles tendon is often seen with pes planus (flatfoot) and may be caused by peripheral nerve lesions, nerve root problems, or atrophy resulting from disuse after injury.
Image provided by:
http://moon.ouhsc.edu/dthompso/gait/KNMATICS/stjclos.gif
Lateral View: Check the medial longitudinal arch of the foot.
As previously mentioned, if the subtalar joint is supinated the medial longitudinal arch will appear more elevated or accentuated. Conversely, when the subtalar joint is in a pronated position the medial longitudinal arch will appear depressed or flat footed.
In Sitting[1]
Anterior View: Check the alignment of the toes.
Supination: The Great Toe will appear elevated compared to the lateral four digits.
Pronation: The Great Toe will appear depressed compared to the lateral four digits.
Image provided by:
http://www.foot-orthotics-prosthetics.co.za/Evaluation-Foot-Orthotics/Evaluation-Foot-Orthotics.html
Further investigation is warranted to determine if the abnormal orientation of the toes are due to the subtalar joint versus midfoot or forefoot. Finding subtalar joint neutral position will help determine where the excess motion is coming from.
In Prone[1]
Posterior View: Check the alignment of the calcaneus and foot.
Supination: The calcaneus and foot invert, plantar flex, and adduct around a stable talus.
Pronation: The calcaneus and foot evert, dorsiflex, and abduct around a stable talus.
Gait Evaluation [2]
When performing a gait evaluation, the examiner should consider the complex kinematic relationship involving the leg and talus (as a common unit) with respect to the position of the calcaneus. The calcaneus remains relatively stationary during the stance phase of gait, and the orientation of the subtalar joint (pronation/supination) changes due to the movement of the leg and talus. However, during the swing phase of gait, the calcaneus moves in relation to an essentially stationary talus. Examining the wear patterns of the patients shoes will help indicate whether excessive supination (lateral-wear) or pronation (medial-wear) is present.
Stance Phase (Weight Bearing)
1. Initial contact - subtalar joint ~2-3 degrees
2. Loading phase - subtalar joint rapidly everts as leg and talus internally rotate
3. Midstance - subtalar joint continues to evert to a maximum of ~3 degrees then moves toward inversion
4. Terminal stance - subtalar joint is in a neutral position and continuing to invert as the leg and talus externally rotate
5. Pre-swing - subtalar joint reaches its maximal inverted position at ~6 degrees
Swing Phase (Non-Weight Bearing)
1. Supination - twists the sole of the foot inward
- Deviation of ankle supination during swing phase may indicate dorsiflexion/eversion weakness/paralysis
2. Pronation - twists the sole of the foot outward
Supination naturally occurs in the gait cycle in order to push-off and propel ourselves forward as it forms a rigid lever at the foot. In order to do this movement @ the ankle/foot: the calcaneous inverts, the transverse tarsal joint everts (raises medial-longitudinal arch), and the forefoot also everts to maintain the foot flat on the floor.
- Hindfoot Varus patients may have excessive supination and limited pronation. This deformity commonly results in genu varum and pes cavus foot. Due to the extra pronation necessary at the beginning of stance, normal supination during early propulsion may be prevented.
- Pes cavus (Rigid Foot) patients have reduced shock absorption ability and will have trouble with repetitive stress activities.
Pronation naturally occurs in the gait cycle to absorb weight bearing forces in the foot. In order to do this movement @ the ankle/foot: the calcaneous everts, the transverse tarsal joint inverts (lowers the medial-longitudinal arch), and the forefoot follows to invert and maintain the foot flat on the floor.
- Hindfoot Valgus patients may have excessive pronation and limited supination. This deformity commonly results in genu valgum (knock knees) and pes planus foot.
- Pes Planus (Flatfoot) patients experience flexed knee and hip positions due to excessive internal rotation of the leg and commonly have issues ranging from patellofemoral pain to low back pain.
Palpation
Examiner uses the thumb of one hand to exert a force plantarly on the foot and uses the contralateral hand to sense any resultant subtalar joint motion at the fifth metatarsal head. If the thumb pushing on the plantar foot is medial to the subtalar joint axis, then subtalar joint supination occurs, and if the thumb pushes lateral to the subtalar joint axis, then subtalar joint pronation occurs. If, however, the examiner detects no motion when the thumb pushes on the plantar foot, then that point is the point of no rotation.[3]
Joint Clearing
Range of Motion (ROM)**[4]
True Subtalar ROM- Patient in Prone
Supination: Inversion Component
- With alignment of goniometer
Axis-Over calcaneal tendon in line with malleoli
Stationary Arm- Posterior midline of leg
Moving Arm- Posterior midline of calcaneus
—Patient performs calcaneal inversion
Normal = 35 degrees
Pronation: Eversion Component
- Same alignment as above
—Patient performs clacaneal eversion
Normal = 15 degrees
Manual Muscle Testing (MMT)
Assess Plantarflexion strength (standing)
Dorsiflexion strength (sitting)
Inversion/Eversion (sitting)
VIDEO
Special Tests[5]
Homan's Sign
Purpose: Assess for thrombophlebitis of the lower leg
Position: Supine
Technique: Passively dorsiflex the foot and squeeze the calf
Interpretation: + test= sudden pain in the posterior leg or calf (Gulick 2009)
Thompson's Test
Purpose: Assess for Achilles tendon rupture
Position: Prone
Technique: Passively flex the knee to 90 degrees and squeeze the middle 1/3 of the calf
Interpretation: Plantarflexion of the foot should occur; + test = failure to plantarflex
Bump Test
Purpose: Test for stress fracture
Position: Non weight-bearing—ankle in neutral
Technique: Apply a firm force with the thenar eminence to the heel of the foot
Interpretation: + test= pain at the site of the possible fracture
