Subtalar Arthroereisis A surgical procedure where something is placed below the talus (ankle bone) with the intended functionto block or limit excessive talar motion.
Sub-talar Arthro - ereisis(below the talus/ankle bone) (joint) (blocking/ear-re-sis)
Specifically,there is a blocking/limiting of motion of the lateral process of the talus.
The device acts at the lateral/superficial outer half of the naturally occurring spacebelow the talus – the sinus portion of the sinus tarsi.
A subtalar arthroereisis device is: placed into a drilled-out hole in the calcaneusor simply inserted into the sinus tarsi space until the leading edge of thedevice reaches the half-way point of the neck of the talus.
Either way, subtalar arthroereisis blocks or limits motionof the lateral process of the talus.
This limiting/blocking stops the forward/inwardrotation of the lateral process of the talus which in turn limits or reduces the amount of pronation of the talotarsal/subtalar joint complex.
Subtalar Arthroereisis is not a new idea.The procedure originated in the 1940s.
Subtalar Arthroereisis Devices have undergone many decades of design changes to try to decrease the removal rate.
Unfortunately, even with all the device design changes, the subtalar arthroereisis devices have a higher than accepted removal ratewhich makes this procedure questionable in the minds of most foot surgeons.
Subtalar arthroereisis should be used in conjunction with other surgical procedures.
38% to 100% of subtalararthroereisis procedures results in the removal of the stabilization device.
This is due to• device displacement• patient intolerance/pain• failure of the device to achieve talar stability• mandate for device removal within 12-18 months after placement
What is the primary underlyingcause that has led to the failure ofwhat could be “the most powerfulorthopedic surgery” performed on the human body?
It stems from - the biomechanical principalsof the talotarsal joint complex.
So, where the implement/device is placed andhow the implement/device acts to prevent the abnormal talotarsal motion.
Biomechanical principals of the talotarsal joint complex.
Talotarsal Joint Complex has 2 primary complex motions Supination Pronation• Talus externally/laterally • Talus internally/medially rotates on the rotates on the calcaneus/navicular (combined calcaneus/navicular (combined with slight plantarflexion and with slight dorsiflexion and eversion). inversion).• A stable/normal talotarsal • A stabile/normal talotarsal joint should have 2/3 joint should have 1/3 supinatory motion. pronatory motion.• Acts to lock the joints of the • Acts to unlock the foot to foot to create a stable lever- adapt to the weightbearing arm. surface.
Talotarsal Joint Dislocation/DisplacementLeads to a longer period of pronation. This equals instability of the footbones when they should be stable and getting ready to propel the foot.