Arthroereisis technique – current materials and implant design

Botezatu I , Marinescu R, Laptoiu DColentina Clinical Hospital Bucharest

Subtalar arthroereisis

Subtalar arthroereisis can be the first procedure for many patients with varying degrees of flexible flatfoot pathology. It is a practical option to correct painful flexible flatfoot when other non-surgical treatments have failed, both in pediatric and adult patients.

Subtalar arthroereisis

Arthroereisis is defined as the limitation of exogenous joint motion without complete arthrodesis using specialized implants. This procedure, which involves placing a motion blocking implant within the sinus tarsi, has been designed to restrict excessive subtalar joint (STJ) pronation while preserving supination .

Subtalar implants

Vogler Biomechanical Classification classified the implants as A axis-altering prosthesis, B impact-blocking device or C self-locking wedge

Subtalar Implants

Subtalar Implants

- Since 1976 – one of the first in use

- UHMWPE- Platform in sinus

tarsi to elevate subtalar joint

- Stem in calcaneal bone

Subtalar Implants

- UHMWPE- Angled disk & peg

design- Angled disk to

block the talus movement

- Softened edges to reduce the possibility of wear particulate

- Cannulated for accurate insertion

Subtalar Implants

- Titanium- Concaved distal

entrance into guide wire opening to allow self centering of guide pin for removal

- More aggressive first thread for easier insertion

Bioabsorbable Barrel Design

Subtalar Implants

Mostly Metallic

Also Bioabsorbable

Arthrex ProStop -Initially PLLA, avoiding the need for secondary implant removal

Special implants – the design- One-piece titanium alloy - Intended to block the forward, downward, and medial displacement of the talus, thus allowing normal subtalar joint motion but limiting excessive pronation.- The spherical shape mitigates potential lateral pressure points - Deep pitch distal anchor thread for canalis tissue engagement - Trestle structure with up to 75 micro channels designed for intention of quicker tissue integration to reduce implant migration

Special implants – the expandables

Surgical technique

- Minimally incision- Insertion of guide-

wire

Surgical technique

Fluoroscopic control of position and size

Surgical technique

Surgical technique

ResultsRadiographic data and subjective results have been promising for both pediatrics and adults.

Reviewing case series data within the past decade revealed a satisfaction rate ranging from 81% to 90% for pediatrics and 78% to89% reported for adult patients

Needleman RL. A surgical approach for flexible flatfeet in adults including a subtalar arthroereisis with the MBA sinus tarsi implant. Foot Ankle Int 2006;27:9.Koning PM, Heesterbeek PJ, de Visser E. Subtalar arthroereisis for pediatric flexible pes planovalgus: fifteen years experience with the cone-shaped implant. J Am Podiatr Med Assoc 2009;99:447Viladot R, Pons M, Alvarez F, et al. Subtalar arthroereisis for posterior tibial tendon dysfunction: a preliminary report. Foot Ankle Int 2003;24:600

Some mechanical complications

Anterior Displacement of a too small implant – surgeon error

Some mechanical complications

Pain in the sinus tarsi requiring removal of the implant – implant related problem

Some material problems

Fragmentation of PLLA implant at several years post-implantation still requiring removal surgery

Some material problems

Synovitis with UHMWPE

ConclusionsSubtalar arthroereisis is a relatively simple but not necessarily un complicated procedure.

With correct indications and associated surgical techniques, long term clinical results can be very effective.

Some studies discuss that current width and length ofthe commercially available especially cylindrically shaped implants may need to be modified!

Even bioabsorbable implants may still require removal surgery!