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The Accessory Navicular

The accessory navicular is an extra piece of bone on the inside of the foot just above the mid-foot ( arch ) in close proximity to its top point. The bone is enclosed within the tibialis posterior tendon that inserts to the navicular bone towards the top of the mid-foot. The additional bone is also referred to as os navicularum or os tibiale externum. It is congenital, so is present from birth. There are various types of accessory navicular and the Geist classification is frequently used. This categorization divides the accessory navicular into 3 variations:

Type 1 accessory navicular bone:
This is the typical ‘os tibiale externum’ making up 30% of the occurrences; it’s a 2-3mm sesamoid bone embedded inside the distal portion of the tendon with no connection to the navicular tuberosity and may be divided from the bone by up to 5mm

Type 2 accessory navicular bone:
This type makes up about 55% of the extra navicular bones; it’s triangular or heart-shaped and linked to the navicular bone via cartilage material. It may well eventually merge to the navicular to create one bone.

Type 3 accessory navicular bone:
Pronounced navicular tuberosity. This might have been a Type 2 that’s merged to the navicular

The common symptom associated with an accessory navicular is the enlargement on the inside side of the arch. Because of the extra bone there, this affects how well the mid-foot muscles do the job and can lead to a painful foot. Rigid type shoes, such a ice skates, may also be very uncomfortable to use because of the enlarged pronounced bone.

The treatment is usually geared towards the signs and symptoms. If the flatfoot is a concern, then ice, immobilisation and pain relief medication may be required initially. Following that, physical therapy and foot orthotic inserts to aid the foot are used. If the soreness is due to pressure from the type of footwear that must be worn, then doughnut type padding is used to get load off the sore region or the footwear may need to be modified.

If these non-surgical treatment options fail to minimize the symptoms of the accessory navicular or the issue is a continuing one, then surgical procedures might be an appropriate option. This involves taking out the accessory bone and restoring the insertion of the tibialis posterior tendon so its function is improved upon.

Abebe Bikila and His Barefoot Marathons

Abebe Bikila was a marathon runner from Ethiopia, winning double Olympic gold medals: Rome in 1960 and at Tokyo in 1964. Abebe died in 1973 at the age of forty one because of troubles after having a motor vehicle accident. There’s a athletic field in Addis Ababa named after him. Google honored Abebe using one of their doodles on what could have been his 81st birthday celebration on 7 August 2013.

1960 Olympic Marathon at Rome:
Abebe had been a last minute substitute in the Ethiopian squad for the Olympics. Abebe had no shoes to compete in and Adidas, the official supporter simply had a few pairs remaining that didn’t fit him, therefore he ran the marathon barefoot (he previously had been running barefoot). Abebe won the gold medal in a time of 2hr 15min. Following the marathon, addressing an inquiry as to the reasons he competed without shoes, Bikila answered: “I wanted the whole world to know that my country, Ethiopia, has always won with determination and heroism.

1964 Olympic Marathon in Tokyo:
Forty days prior to the marathon Abebe was operated on for an acute appendicitis and at one stage it was thought that he might be unable to run. He went on to win this marathon in a world record time of 2hr 12min, being the 1st runner to win two Olympic marathons. Abebe had been wearing Puma shoes in the race (which Abebe Bikila also ran in to come 5th in the 1963 Boston Marathon).

He is a light to mild heel striker with a few midfoot strikes also. Despite that, he is not overstriding and could crack a world record. Bikila is frequently idolized by the barefoot running online community as a idol for running the marathon without running shoes (together with other elite athletes). Pundits of this love to point out that he did compete faster and break a world record when using footwear.

As part of his legacy, the minimalist running shoe producer, Vibram FiveFingers have the Bikila label of their range named after him. Early in 2015, the descendants of Abebe Bikila reported they were taking a law suit against Vibram for registering the ‘Bikila’ title without having authorization.

The Abductory Twist

An abductory twist is an observation which is noticed during an observation of the running. Just as the heel begins to unweight or raise up the floor there’s a quick sudden abduction or twist noticed of the heel. This is a commonplace finding during a gait evaluation, however its clinical relevance is actually of some question.

There are a number of reasons for this abductory twist. One is that because rearfoot is pronating (moving inwards at the rearfoot) this is attempting to internally turn the leg. While doing so the other leg is in the swing phase moving forward and is attempting to externally rotate the lower limb. The lower limb is ‘battling’ with these two opposite forces. Friction between the ground and the foot keeps the heel from moving. Immediately after force begins to come off the heel, the external rotation force from above is now able to abduct the rearfoot and it does so rapidly. A second explanation is that there is a condition at the great toe joint in which it does not enable dorsiflexion correctly. This might be a hallux rigidus, a functional hallux limitus or a issue with the windlass mechanism which affects motion at the big toe joint. As this motion is difficult to begin, the body abducts the heel to move medially about that joint. A third reason which is often only found in the physical therapy literature is that the twist is due to control of motion about the hip joint. In that literature it is often described as a medial heel whip.

The cause of debate around the clinical importance is that it is merely an observation seen when doing a gait analysis that is caused by something else (ie, losing friction with the ground, a problem at the great toe joint or maybe the hip joint). If it is a concern, then management is directed at what is creating the abductory twist or medial heel whip rather than directed at the abductory twist alone. The management options to get rid of it is going to be very variable dependent on what is the best management decision for the reason.