Ankle joint range of motion:
During normal gait, the leg has to move over the foot at the ankle joint (2nd rocker) by about 10 degrees (actual value will depend on activities).
• patient is prone, the posterior aspect of the calcaneus is place in the frontal plane and the subtalar joint is maintained in its neutral position
• bisection of the lower one third of the lateral aspect of the leg is made
• foot is dorsiflexed to resistance
• the angle between the leg bisection and the plantar plane of the foot is observed or measured
• the test is done with both the knee flexed and extended (do extended knee first – if range is adequate, the flexed position does not need to be measured/assessed).
• foot is placed perpendicular to wall and then lunge with the knee towards the wall
• foot is progressively moved away from the wall until the maximum range of dorsiflexion is reached without the heel leaving the ground
• can measure the distance of the foot from the wall or the angle of the tibial shaft
• advantage is that the test is performed weightbearing
• in all literature on this test, nothing is mentioned about keeping the subtalar joint neutral (pronation at STJ would increase apparent range)
• Bennell et al (1998) showed this method has excellent reliability
Equipment has been developed to make the measurement of ankle dorsiflexion more reliable (eg: Keating et al , 2000)
• if limited when knee is extended osseous block, soft tissue limitation in soleus and/or gastrocnemius
• if limited when knee is flexed osseous block, soft tissue limitation in soleus
• if range of motion is severely inadequate toe gait with no heel contact
• if less severe heel will tend to come off the ground prematurely (may depend on range of motion at subtalar and midtarsal joints) or the foot will pronate at the subtalar and midtarsal joints to use some of the dorsiflexory motion available at these joints (the actual amount at each joint will depend on the orientation of their joint axes and the ranges of motions)
• determine if restricted range of motion is soft tissue or osseous (feel at end range of motion)
Also need to check that the superior tibiofibular joint is mobile and that this is not restricting ankle joint motion.
Sources of error:
• not maintaining subtalar joint in its neutral position (pronation at the subtalar joint will increase the apparent range of motion at the ankle joint due to the dorsiflexory component of pronation)
• incorrectly drawing of bisection
• forefoot dorsiflexed on rearfoot (subluxed at midtarsal joint)