Leg Length Discrepancy (LLD)
Rearfoot Varus and Forefoot Supinatus
Forefoot Equinus
External Tibial Torsion
Hallux Limitus

Leg Length Discrepancy (LLD)
It is relatively normal to have one leg shorter than the other as not many people have perfect symmetry. In the presence of a leg length discrepancy what is important is to determine the magnitude and whether it is relevant to the patient’s problem.

Leg length discrepancies can be structural in nature and due to differences size of the thigh, shin, and even heel bones and therefore unable to be changed, or functional resulting from other dysfunctions which can often be eliminated to restore leg length equality such as asymmetries in pelvis alignment or excessive pronation of a foot in standing.

Inequality of leg length leads to many compensations including head tilt and shoulder drop towards the longer leg, asymmetry of arm swing, and circumduction of the longer leg during the swing phase of gait. Commonly it drives excessive lateral tilting of the pelvis (a Trendelenburg sign) when the individual lands on the longer leg, and in particular is associated with low back and pelvis symptoms.

Assessing for leg length difference is difficult so our clinicians carefully screen for it as part of an overall approach. Video gait analysis can then help clinicians to evaluate what is significant and to decide if correction is warranted with shoe modification and /or orthotic devices.

Rearfoot Varus and Forefoot Supinatus
Rearfoot varus occurs when the heel bone is inverted (turned in) in relation to the lower leg generally due to structural changes in the subtalar joint.

Forefoot supinatus is an abnormality where the forefoot is angled so that the bottom of the forefoot is turned inward in relation to the rearfoot.

Both rearfoot and forefoot varus drive over-pronation (‘rolling in’) of the foot to allow the inner side of the heel or forefoot to contact the ground as the foot progresses from heel to toe during the stance phase of walking.

Forefoot Equinus
This skeletal driver represents a bony shape of the foot where the forefoot is lower to the ground than the heel giving the foot a high arch appearance. Equnis can be fixed, that is structural in nature and therefore unable to be changed, or mobile in which lack of flexibility of the calf muscles is often a contributing factor.

The presence of a forefoot equnis forces a person to use up some of their ankle joint motion just to stand upright as this ankle movement is needed to get both the forefoot and the rearfoot onto the ground. The result is that when walking there is little of this movement left over to allow the lower limb to move up and over the foot during stance phase, and as such various compensations can occur.

Commonly compensation for this blockage to ‘straight-line’ movement of the ankle is via excessive pronation of the foot often associated with an abducted or ’10 to 2’ gait, and early heel lift. With early heel lift body weight is transferred prematurely to the forefoot predisposing the individual to calf and Achilles tendon injuries.

It is important to screen for this common foot type when looking at patterns of injury in the lower limb and is commonly overlooked as it does not represent an obvious disadvantage when observed non-weight bearing.

External Tibial Torsion
We all have an element of tibial torsion which in most cases is within normal limits. Tibial torsion is where the bony shape of the tibia (lower leg) is twisted, and in those with increased external tibial torsion the amount of torsion is such that their foot and ankle point outwards in relation to the rest of the lower limb.

The consequence of an increased external tibial torsion is an abducted gait, that is walking with the feet turned out at ’10 to 2’. When we walk our body weight progresses forward over our feet in the direction we are moving (i.e. straight ahead), but if our feet are abducted (‘turned out’) then when this body weight moves forward of our heels it will drive our feet to pronate or ‘roll in’ excessively which can place excessive strain on structures in the lower limb, especially at the knee.

Hallux Limitus
Hallux limitus simply means stiffness of the 1st MTP (big toe) joint. For such a small joint it has a very important role in foot function. During the propulsive phase of walking the 1st MTP joint is extended backward as we move up onto our forefoot just before toe-off, adequate movement in this joint is crucial in allowing the foot to progress from heel to toe with ‘straight-line’ mechanics.

Extension of this joint also places tension on tissues underneath the foot (plantar fascia) which help to lift the arch of the foot and stiffen the forefoot (something known as the windlass mechanism) so that it functions as a rigid lever in order to enable effective propulsion.

Restriction in extension of this joint limits the ability of the foot to progress in a straight-line and the foot is forced compensate by twisting away as the heel leaves the ground therefore introducing increased rotational forces to the lower limb. Additionally without adequate extension of the joint the windlass mechanism fails to initiate leaving the foot inadequately stabilised during the propulsion phase.

Hallux limitus is an underlying cause of a number of conditions including Iliotibial Band Syndrome, Plantar Fasciitis, and some blistering or callus formation in the arches of the foot. Pain in the big toe itself may also result from the restriction, generally in the sesamoid complex which these are the small bones that sit under the big toe joint and are susceptible to stress fractures.

Video gait analysis is used to identify the presence of Hallux limitus and to assess the compensatory movements it may be causing, and to determine whether treatment with orthotic devices will help.