1) STJ Arthroresis Flashcards
Arthroresis
- From Greek root ereisis “propping up”
- Props up supporting talus
- “operation limiting motion in a joint”
- Without complete arthrodesis
STJ arthroresis used for treatment of
- Flexible flatfoot (no DJD, no Tarsal coalition)
- Expanded indications for adults with or without PTTD
- Equinus must be addressed
Motion-blocking implants
- Placed in sinus tarsi
- Restrict excessive STJ pronation while preserving supination
- Originally designed for pediatric flexible flatfoot
Anatomy of the sinus tarsi
- Wider portion directed anteriorly and laterally
- Medial portion narrows to a transverse cylindrical space (tarsal canal/canali tarsi)
which terminates posterior to the sustentaculum tali of the calcaneus
Sinus tarsi contents
- Ligaments (5)
- Adipose connective tissue
- Branches of the peroneal and posterior tibial arteries which anastomose in the sinus
- Cutaneous dorsolateral nerve (a branch of the superficial peroneal nerve), and proprioceptive nerve endings
5 ligaments of the sinus tarsi
- Interosseous talocalcaneal ligament(ITCL) aka interosseous ligament
- Cervical ligament(aka Fick ligament, oblique talocalcaneal ligament, or lateral talocalcaneal ligament)
- Medial root of the inferior extensor retinaculum
- Intermediate root of the inferior extensor retinaculum (aka intermediary root)
- Lateral root of the inferior extensor retinaculum
Interosseous talocalcaneal ligament(ITCL) aka interosseous ligament
- Most medial ligament in tarsal canal
- Functions to stabilize the STJ
Cervical ligament(aka Fick ligament, oblique talocalcaneal ligament, or lateral talocalcaneal ligament)
- Located anterior and lateral to the interosseous ligament
- Attaches to inferolateral talar neck and dorsal neck of the calcaneus
- Limits inversion, and also stabilizes the subtalar joint
Medial root of the inferior extensor retinaculum
- Located posterior and medial to the cervical ligament
- Attaching to the calcaneus at the floor of the medial sinus
- Often merging with the calcaneal attachment of the interosseous ligament
Intermediate root of the inferior extensor retinaculum aka intermediary root
- Attaches to the calcaneus just posterior to the cervical ligament, coursing anteriorly and superiorly over the medial margin of the extensor digitorum longus tendon
Lateral root of the inferior extensor retinaculum
- Loops around the lateral margin of the EDB tendon, merging with the intermediate root to form a sling-like structure over the tendon
- The lateral fibers course posteriorly and laterally, attaching to the lateral cortex of the calcaneus or blending with the deep fascia
STJ Mechanics
- During pronation, the lateral process of the talus rotates forward as the talus plantarflexes and adductus
- Further pronation is blocked as lateral process contacts floor of sinus tarsi
Chambers was first to note that by elevating the floor of sinus tarsi
- Excessive pronation could be prevented
- Accomplished with autogenous bone graft placed under leading edge of the posterior facet of the calcaneus
- Served as basis for many different STJ arthroereisis procedures
STJ biomechanics
- Triplanar joint with varied axis throughout ROM
- Generally axis courses posterior, plantar, lateral to anterior, dorsal, medial
- Average STJ maintains equal amounts of transverse and frontal plane motion
- Ankle joint generally has majority of sagittal plane motion
- Average STJ ROM 30 degrees from “neutral” (20 degrees of inversion, 10 degrees of eversion)
STJ CKC pronation
- Visualized as calcaneal eversion and/or talar tibial inversion, talar plantarflexion and adduction
When executed correctly STJ arthroereisis, restricts
- Excessive CKC pronation
- Resetting maximally pronated position, less calcaneal eversion and foot abduction
Stabilizes foot for proper propulsion
Planal dominance
- The more that a joint axis deviates from one of the cardinal body planes, the more the motion will occur in that body plane
STJ axis of rotation
- Plantar posterior-lateral –> Dorsal anterior-medial
- 42T, 16S
- Transverse & frontal plane motion
Low STJ axis
- If the axis falls in the transverse and sagittal planes, the motion will occur in the frontal plane
High STJ axis
- If the axis falls in the frontal (vertical) and sagittal planes, the motion will occur in the transverse plane
When the high STJ axis is oriented twice as close to the vertical plane than the horizontal,
- Twice as much motion will occur in the transverse plane as the frontal plane
When the STJ axis is Low oriented twice as close to the transverse plane than the vertical,
- Twice as much motion will occur in the frontal as the transverse
When the axis is oriented equidistant between the two,
- You get equal motion in the transverse and frontal planes (ideal/average at 42)
High STJ axis summary
- Axis parallel to Sagittal = Transverse motion dominant (ABD/ADD)
Low STJ axis summary
Axis parallel to Transverse = Frontal motion dominant (INV/EVE)
Frontal STJ axis summary
- Axis parallel to Frontal = Sagittal motion dominant (DORSI/PLANTAR)
STJ arthroresis indications
- Flexible planovalgus deformity (pediatrics and adults)
- Accessory navicular
- Resected tarsal coalition
- Stage II PTTD
- Absence of pain does not preclude surgical intervention
- Indications still being refined!
STJ arthroresis cautions
- Obese patients
- Significant Gastroc/Soleus/ankle equinus
- Excessively medial deviated STJ axis
- Results in implant being subjected to extremely high impact forces within sinus tarsi leading to Chronic Sinus Tarsalgia or pathologic boney changes
Transverse plane deformity clinical clues
- “Too many toes” sign
- Medial bulge
- Uncovering of talar head
- Axis parallel to Sagittal = Transverse motion dominant (ABD/ADD)
Frontal plane deformity clinical clues
- Lateral fold of foot
- High degree of calcaneal eversion
> 15 degrees - Axis parallel to Transverse = Frontal motion dominant (INV/EVE)
Sagittal plane deformity clinical clues
- Midfoot sag
- Medial column compromised
- Talar declination does not line up with first metatarsal shaft
- Axis parallel to Frontal = Sagittal motion dominant (DORSI/PLANTAR)
Radiographic analysis of STJ
- Normal hindfoot alignment
- Talus sits on top of calcaneus
- Sinus tarsi in “open position”
- Unbroken cyma line
Radiographic abnormal hindfoot alignment
- Talus not sitting on calcaneus
- Collapse of sinus tarsi
- Anterior cyma line break
Transverse plane dominance radiographic analysis
- Talocalcaneal angle (Kites Angle) > 30°
- Cuboid abduction angle
- Wedge shaped navicular
- Talonavicular coverage > 7°
Sagittal plane dominance radiographic analysis
- Talar declination angle > 21°
- Talo – 1st met (Meary’s) angle > 15-30°mod
> 30° severe - Talocalcaneal angle on lateral view > 25°
- Calcaneal Inclination angle < 15°
- Midfoot sagging, Naviculocuneiform breach
Frontal plance dominance radiographic evaluation
- Rearfoot eversion
- 1st met declination angle
- Height of sustentaculum tali
Special radiographic views
- Charger View
- Harris & Beath
Charger view
- Stress dorsiflexion lateral view
- Osseous block of AJ
Harris & Beath view
- R/O talocalcaneal coalition of posterior and middle facets
Sagittal plane procedures
- Kidner
- FDL transfer
- Lowman
- Young
- MAS
- Cotton
Frontal plane procedures
- Calcaneal slide
- Reverse Dwyer
- Silver
- Arthroresis
Transverse plane procedures
- Evans
- Medial based osteotomy
Kidner (sagittal)
- Removal of accessory navicular
- Transposition of posterior tibial tendon to reduce slack
FDL transfer (sagittal)
- Sacrifice FDL distally to transfer to navicular or along the P tendon
- Attach distal stump to FHL
Lowman (sagittal)
- TAL
- TN wedge arthrodesis
- TA under navicular and suture spring ligament
- Desmoplasty of the spring ligament on self
Young (sagittal)
- TAL
- TA transposed with navicular creating new plantar ligament
- Advancement of spring ligament on self
MAS (sagittal)
- Young plus PT tendon advancement
- Tightening of spring ligament
- FDL tendon transfer
Cotton (sagittal)
- Opening wedge medial cuneiform
- Cut parallel to N-C joint
- Keep plantar cortex intact
- Reduction of elevatus
- Stabilize medial cuneiform
Calcaneal slide (frontal)
- Medial translocation of posterior fragment of calcaneus
- Corrects frontal plane deformity
- Alters pull of gastroc-soleus muscle group
Reverse Dwyer (frontal)
- Lateral closing wedge located between posterior STJ facet and the Achilles attachment
Silver (frontal)
- Opening wedge bone graph on lateral calcaneus
- Posterior calcaneus is translated plantarly and medially
Arthroresis (frontal)
- Usually performed with implant that limits STJ eversion
Evans (transverse)
- Lateral column lengthening procedure
- Opening wedge approximately 1.5 cm from calcaneocuboid joint with insert of bone graft or block plate
- Triplanar correction (primarily transverse) with realignment of midtarsal joint and reduction of calcaneal inversion
- Improvement of arch height and stabilization
Medial based osteotomy (transverse)
- Medial base wedge to allow for shortening of the medial column and reduction of the abduction deformity
STJ arthroresis milestones
- Chambers (1946)
- Grice (1952)
- Haraldsson (1962)
- Subotnick (1974)
Posterior facet osteotomy (Chambers 1946)
- Correction of flexible flat feet in adolescents
Extra-articular STJ arthrodesis (Grice 1952)
- Extra-articular arthrodedid of suprastragular joint for correction of paralytic flat feet in children
Bone wedge arthroresis (Haraldsson 1962)
- Operative treatment of pes planovalgus staticus in juveniles
Custom carved plug (Subotnic 1974)
- STJ lateral extra-articular arthroresis
Axis-altering implant (Smith 1976)
- Ultra high molecular weight polyethylene (HMPE)
- Platform and Stem
- In sinus tarsi
- Posterior facet arthroplasty to seat the implant
- Different sizes
- Elevating the subtalar joint axis reduces hindfoot eversion
Vogler biomechanical classification (1987)
- A = self-locking
- B = axis-altering
- C = impact-blocking
Self-locking (not axis-altering) implants
- Any material inserted into lateral sinus tarsi, restricting eversion of STJ
- Implant prevents contact of the lateral talar process with floor of sinus tarsi, restricting pronation
- Valenti – “grandfather” of threaded cylinder implants , 1976
- MBA, Maxwell-Brancheau - 1997
- HyproCure, Graham, 2004
- Futura Conical (Wright Medical)
Axis-altering implants
- These implants elevate the floor of the sinus tarsi, altering the low STJ axis reducing frontal plane eversion
- Implant stem is placed in vertical orientation in the floor of calcaneus
- Pronation is limited by preventing excessive plantarflexion of the talus as it rides on implant
- Primarily used with FRONTAL plane deformities
- Does not work well with high STJ Axis
Impact-blocking implants
- Without changing STJ axis, these implants block the lateral process of the talus from advancing beyond the posterior facet
- STA-Peg implants
Surgical pearls STJ Axis parallel to Transverse (Low STJ axis) = Frontal plane dominant motion
- Koutsogiannis
- Dwyer
- Silver
- Arthroereisis*
Surgical pearls STJ Axis parallel to Sagittal (High STJ axis) = Transverse plane dominant motion
- Kidner
- Evans*
Surgical pearls STJ Axis parallel to Frontal = Sagittal plane dominant motion
- Young
- Cotton
- Lapidus
Koutsogioannis calcaneal osteotomy
- Medial displacement osteotomy (~1cm)
- Through and through
- Parallel to & behind peroneal tendons
- Posterior calcaneus shifts medially
- Restore heel beneath ankle
Reverse Dwyer calceneal osteotomy
- Medial closing wedge
- Varus producing
Silver calcaneal osteotomy
- Lateral opening wedge with graft
- Directly posterior to posterior facet
- Varus producing
Evans calcaneal osteotomy
- Extra-articular correction
- Lengthens lateral column
- Realign midtarsal joints
- 1.5 cm proximal to calcaneocuboid joint
- Insertion of bone graft anteriorly
