Sinus tarsi syndrome

What is it?

The intervention of sine-tarsal arthrorisis consists in the introduction of a truncated cone screw (endorthesis) inside the sinus tarsus percutaneously. The screw has a proprioceptive function, modifying the attitude of the hindfoot by imposing an adaptation of the capsular and muscular structures involved in the maintenance of the plantar arch.

Technical difficulty:
Average duration of the intervention:
15 minutes
Average duration of hospitalization:
0-1 day

When is this procedure indicated?

The surgical indication in the evolutionary flat foot of the child is given after the age of 8-9 years depending on the growth coefficient, in the presence of flat feet that do not show improvement and present important functional limitations due to excess pronation. The indicator commonly used to identify the correct timing of intervention is the measurement of the patient's foot, which compared to that of the parents, allows to approximate an adequate state of growth: the intervention gives the best results when the foot is still growing and the soft tissues are able to adapt to the changes imposed by the endorthesis.

How is it performed?

The main point of contact is the sinus tarsi, located anterior and inferior to the peroneal malleolus. A guide wire is inserted into the tarsal sinus after a skin incision, with anterior to posterior and plantar to dorsal tilt.  Occasionally, additional surgical maneuvers may be necessary: percutaneous Achilles tendon lengthening in case of stiffness at the dorsi-flexion of the foot or medial capsular retensioning in case of excessive laxity.

Special expanders are used on the guide wire in increasing size, which prepare the housing of the definitive implant, taking care to clinically evaluate the correction: realignment of the hindfoot and restoration of the plantar vault.

The size of the implant corresponds to the diameter of the last expander used and the correct positioning will be evaluated by an intra-operative control X-ray.


In most cases, the patient is mobilized immediately with the aid of two crutches with tolerance load on the operated limb for the first 7-10 days. Full loading and return to normal daily activities occurs gradually within 30-40 days. In selected cases, it is preferable to temporarily immobilize the ankle with a cast boot that is removed at 10-15 days post-operatively.

It is useful to perform proprioceptive gymnastics starting 10-15 days after surgery (or anyway after the removal of the plaster).

The next clinical-radiographic control takes place about 30-40 days after surgery.

Short-term complications

The main complications that can be seen in the early post-operative days include: pain at the site of surgery, redness, superficial skin infections, hematomas, swelling, and stiffness.

Long-term complications

A possible, but infrequent, long-term complication is loosening of the endorthesis, resulting in pain and functional limitation. If radiography confirms that loosening has occurred, surgical intervention is necessary to remove the screw and possibly reposition it if correction has not occurred.

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