A close up view
of
the
subtalar implant By Jay
Lieberman, DPM Subtalar joint arthroreisis procedures are indicated in flexible flatfoot deformities when pathologic subtalar joint motion cannot be controlled by conservative means. A significant component of the deformity is often a gastrocnemius equinus. Prior to the arthroreisis procedure, I commonly perform a Fulp and McGlamry gastrocnemius recession.
The Subtalar MBA�(KMI) Implant used here is a cannulated, soft-threaded, titanium device. It is designed to block the anterior and inferior displacement of the talus, allowing normal subtalar joint motion, while blocking excessive pronation and the resulting sequeula
LINK to more information about KMI's MBA implant A 3cm incision is made over the sinus tarsi, with care taken to avoid both the sural nerve and the intermediate dorsal cutaneous nerve.
The incision is deepened through the deep fascia. The cervical ligament is retracted, allowing entry into the sinus tarsi. The yellow probe is inserted perpendicular to the lateral wall of the calcaneus in a posterior, superior and medial direction. Tenting of skin is seen medially, inferior to the tibialis posterior tendon and anterior and slightly inferior to the medial malleolus. The probe is use to dilate the sinus tarsi and sinus canalis.
A guide pin is recommended to facilitate insertion of the cannulated implant. A small incision is made medially to allow for exit of the pin. The sizer tools (6mm, 8mm, 9mm, 10mm, and 12mm) are placed over the pin to determine the correct size of the implant. The proper sizer tool will limit "abnormal" eversion, yet allow for 2-4 degrees of subtalar eversion.
Prior to insertion of the actual sterile implant, the sizer implants are used to assess positioning and range of motion.
With the use of intra operative imaging, the precise position of the implant is visualized. The leading edge of the implant should not cross the longitudinal bisection of the talus. The trailing edge should be approximately 5mm medial to the lateral wall of the calcaneus (as seen on AP view).
Once the surgeon is satisfied with size and position of the trial implant, an equivalent size sterile implant is inserted. The wound is then closed and the foot and ankle are immobilized. Both procedures are relatively simple, but offer dramatic post operative results. CASE ONE
CASE TWO
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