Published on October 24, 2012
Michael E. Graham, DPM, FACFAS Macomb, MichiganLong Version
• What is EOTTS?• Rationale/Indications for an EOTTS procedure• Evidence Base – Cadaveric Research – Clinical Research• Conclusions
Extra-Osseous TaloTarsal Stabilization (EOTTS)• The use of an internal fixation device to prevent excessive motion of the talus on the calcaneus and navicular.• Differentiated from – inter-osseous – intra-osseous.• Purely a soft tissues procedure to improve the function of hindfoot mechanism.
When would/should you recommend EOTTS to your patients?
Why has this patient presented to you? What is their chief complaint?Do not limit your attention/treatment focus to symptom relief only. Must identify and eliminate any etiologic factor(s).
Terminology Break• Normal – accepted measurement/value• Abnormal – measurement/value outside of normal• Recurrent- something that happens again and again.• Dislocation- displaced from its normal position or alignment.
Normal TaloTarsal Motion• Supination• Pronation• Normal strain is placed on the supporting structures.• Articular facets of TTM remain in constant congruent contact.• Efficient machine
This is a Normal TaloTarsal Mechanism• “Normal” amount of motion of the talus on the tarsal mechanism.• Articular facets remain in constant congruent contact.• Sinus tarsi remains “open”.
Radiographic Evaluation NORMAL - Weightbearing AP View• Talar Second Metatarsal Angle• Normal < 16 degrees• The bisection of the talus should be lateral to the medial shaft of the 1st metatarsal.
Radiographic Evaluation NORMAL Weightbearing Lateral View• Talar Declination Angle < 26 degrees• Cyma line• Sinus tarsi “open”
This is an Abnormal TaloTarsal Mechanism• Excessive amount of motion of the talus on the tarsal mechanism.• Articular facets do not remain in constant congruent contact.• Obliteration of the sinus tarsi.
TaloTarsal Dislocation• Results in a pathologic talotarsal axis of motion.• Leads to an excessive abnormal amount of pronation (over-pronation or hyperpronation).• The resulting excessive forces will travel abnormally throughout the foot structure.
Radiographic Evaluation ABNORMAL-Weightbearing AP View• Talar 2nd Met. Angle >16 degrees• Transverse plane dislocation deformity
Radiographic EvaluationABNORMAL – Weightbearing Lateral View• Talar Declination > 26 degrees• Anterior deviated Cyma line• Obliterated sinus tarsi• Sagittal plane dislocation deformity
Comparison of NP-TTM vs RSP Evidence for Recurrent Talotarsal Dislocation
Comparison of NP-TTM vs RSP Evidence for Recurrent Talotarsal Dislocation
Clinical Evidence of Recurrent TaloTarsal Dislocation
Recurrent TaloTarsal Joint Dislocation • Is the primary etiologic factor to many secondary foot and ankle disorders. • Every step taken, leads to pathologic forces acting on supporting structures. • Eventually, the weakest link becomes symptomatic. • It is therefore of extreme importance to stabilize the talus on the calcaneus and navicular.
Recurrent TaloTarsal Joint Dislocation (718.37)• Chronic dynamic pathologic deformity of the hindfoot.• Repeated displacement of one or more articular facets of the talus on the calcaneus and/or navicular.• Differentiated from static talotarsal joint dislocation which is a rigid deformity.
Classification of EOTTS Devices• Type I EOTTS: arthroereisis• Type II EOTTS: non-arthroereisis Extra-osseous Talotarsal Stabilization Devices: A New Classification System. Vol. 51, No 5, p. 613-622.
Type I: Subtalar Joint ArthroereisisThe goal is to stop theanterior progression oflateral process by somemethod within the outerhalf of the sinus tarsi. Arthroereisis implants act sole within the lateral half of the tarsal sinus.
Subtalar Joint Arthroereisis• This technique is focused on limiting or blocking the lateral process of the talus. Plantar view of talus
Function – Type I• This device acts/acted as an anterior extension of the lateral process of the talus.
Limits Talar Pronation• As the talus moves from a supinated to pronated position the anterior extension of the talus hit against the posterior aspect of the anterior facet of the calcaneus to block/limit further pronation.
Type I Subtalar Arthroereisis Device Evolution• The initial device had a cylindrical design.• It should be noted that the outer sinus tarsi shaped is conical not cylindrical.• Newer devices were designed with that in mind as well as other features with ways to make device removal easier.
Type I Subtalar Arthroereisis• Unfortunately, the new designs did little to decrease the overall removal rate.• Reported rates from 38% to 100% removal
Type II: Non-arthroereisis Extra-Osseous TaloTarsalStabilization with HyProCure.
Type I – arthroereisis implants limits/blocks talar motion here. Type II- HyProCure stabilizesthe talotarsal mechanism here. HyProCure is not an arthroereisis device.
TYPE IThe leading edge of TYPE IIarthroereisis devices HyProCure come into contact internally stabilizes with the calcaneus the talus at the here. cruciate pivot point here. Top view of the calcaneusType II does not block or limit motion.
Normal amount of pronation and supination is still available with Type II device. (There is a limitation of motion with Type I)
HyProCure stabilizes the talus atthe cruciate pivot point to restorethe talotarsal axis of motion back to normal.
• Cadaveric Based• Retrospective Clinical Findings• Prospective Clinical Analysis
Scientific Evidence Base for EOTTS Type II- Decreased strain to the posterior tibial tendon – 51%- Decreased strain to the plantar fascia – 33%- Decreased strain to tibial posterior nerve- Decreased pressures within tarsal tunnel/porta pedis- Improved post-procedure functional scores- Normalization of abnormal radiographic correction/angles- Low device removal rate <6%- Proven to stabilize the talotarsal joint displacement- Proven to decrease forces acting on the medial column- Internal restoration of navicular height- Improved/normalization of plantar forces
Cadaveric Based Research• Measurement of talocalcaneal joint forces• Strain measurement on: – Posterior tibial tendon – Tibialis posterior nerve – Plantar fascia• Pressure Measurements within the tarsal tunnel and porta pedis
Stabilization of Joint Forces of the Subtalar Complex via the HyProCure Sinus Tarsi StentJournal of American Podiatric Medical Association, Volume 101 No. 5, Pages 390- 399, Sept/Oct 2011 • Proves that HyProCure stabilizes the talus on the tarsal mechanism. • The stabilization of the talus on the tarsal mechanism reduces excessive abnormal forces acting on the medial column of the foot. • Therefore, there would be a decrease in strain on the supporting tissues on the medial column of the foot and decreased strain on these tissue allowing for tissue healing.
Cadaveric Based Research TaloCalcaneal Joint Rebalancing• Premise of this study was to show the excessive force placed anteriomedially onto the middle and anterior talocalcaneal facets.• Transducers were placed into the posterior, middle and anterior TC facets in cadaveric specimens with TTD.
Cadaveric Based Research TaloCalcaneal Joint Rebalancing• The foot was loaded giving maximum pronatory force dislocating the talotarsal mechanism.• EOTTS HyProCure device was inserted and the same maximum pronatory force was again applied.
EOTTS Cadaver Study
Cadaveric Based Research TaloCalcaneal Joint Rebalancing• Findings showed – With TTD, the posterior talar facet forces shifted anteriomedially onto the middle and anterior facets – Upon EOTTS • The forces were stabilized on the posterior TC facet • The excessive force acting on the middle/anterior facets decreased
Talocalcaneal Articulations after EOTTS
Cadaveric Based Research TaloCalcaneal Joint Rebalancing• This proves that excessively abnormal forces are placed anteromedially instead of posteriolaterally• Excessive force there will be placed onto the medial column of the foot
Cadaveric Based Research TaloCalcaneal Joint Rebalancing• Upon EOTTS those forces were rebalanced• Reduction of force anteriomedially and increased force posteriolaterally• Therefore decreasing the forces acting on the medial column
Cadaveric Based Research Strain Measurements• Theorized that recurrent talotarsal dislocation leads to increase strain acting on the posterior tibial tendon, tibialis posterior nerve and the plantar fascia• EOTTS would decrease the strain placed on these structures
Cadaveric Based Research Strain Measurements• Cadaveric specimens exhibiting recurrent TTD were placed on an MTS• Strain gauges were placed on the – Posterior tibial tendon proximal to the navicular tuberosity – Tibials posterior nerve proximal to the porta pedis – Plantar fascia medial band
Cadaveric Based Research Strain Measurements• TTM was maximally pronated• 3 readings per test area each limb• Blinded study (examiner could not see the metrics)• Pressure sensor was placed under the 4th & 5th metatarsal heads to ensure same force was applied for every measurement
Cadaveric Based Research Strain Measurements• First data set was maximum talotarsal dislocation• Second data set was collected using the exact same method after the insertion of the EOTTS device
The Effect of HyProCure Sinus Tarsi Stent on Tarsal Tunnel and Porta Pedis Pressures. Journal of Foot and Ankle Surgery, Volume 50, Issue 1 Pages 44-49, January 2011 • TTD leads to excessive forces acting on the tarsal tunnel and porta pedis. Eventually, this can lead to tarsal tunnel syndrome (the foot’s version of carpal tunnel). This, over time, leads to tibialis posterior neuropathy and loss of feeling to the bottom of the foot and toes. • EOTTS was proven to decrease the pressures within both the tarsal tunnel and porta pedis back to normal range.
Effect of Extra-Osseous TaloTarsal Stabilization onPosterior Tibial Nerve Strain in Hyperpronating Feet: A Cadaveric Evaluation Journal of Foot and Ankle Surgery, Volume 50, Issue 6 , Pages 672-675, November 2011 • Strain and elongation of the tibialis posterior nerve leads to decreased blood flow within the nerve and decreased to complete loss of nerve function. Eventually, tibialis posterior neuropathy forms leading to numbness to the bottom of the foot. • TTD is the primary etiology for this strain in non- traumatic cases. • By stabilizing the talotarsal mechanism, EOTTS with HyProCure was shown to decrease the nerve strain and elongation by 43%, bringing it back to the normal range. • This would benefit patients with TPN.
Nerve Strain/Tension What do we know?• Pronation increases the strain/tension on the posterior tibial nerve – Francis et al: Benign Joint Hypermobility with Neuropathy: Documentation and Mechanism of Tarsal Tunnel Syndrome. J Rheumatol 14:577-581, 1987 – Daniels et al: The Effects of Foot Position and Load on Tibial Nerve Tension. Foot Ankle Int. 19:73-78, 1998
Nerve Strain/Tension What do we know?• 8% venular flow obstructs• 15% complete arterial occlusion occurs – Kwan el al: Strain, stress, and stretch of peripheral nerve. Acta Orthop Scand, 83:267-272, 1992 – Lundborg, G, Rydevik, B: Effects of stretching the tibial nerve of the rabbit. JBJS 55B:390-401, 1973
Nerve Strain/Tension What do we know?• 6 % Strain decreases the amplitude of the action potential which recovers after removal of the strain.• 12% strain produced a complete block and showed minimal recovery – Wall et al: Experimental stretch neuropathy. JBJS 74B:126- 129, 1992
9 Cadaver Specimens % Reduction in Elongation Strain Elongation Without Without EOTTS With EOTTS EOTTS With EOTTS in mm in %Mean ± 1 S.D. 5.91 ± 0.91 3.38 ± 1.20 26.81 ± 4.6 15.38 ± 5.65 43% Range 3.02 - 7.19 1.25 - 5.23 12.5 - 33.87 5.24 - 23.57
Cadaveric Based Research Strain Measurements - Results• Tibialis Posterior Nerve – EOTTS decreased TPN strain by 43% *JFAS Nov/Dec 2011
Cadaveric Based ResearchPressure Measurements within the Tarsal Tunnel• Long been know that over-pronation is a major contributing factor in the development of neuropathy of the tibialis posterior nerve.• Previously published papers have used pressure gauges to measure this.• HOWEVER- no one has shown a method to reduce these forces outside of surgical decompression.
Cadaveric Based ResearchPressure Measurements within the Tarsal Tunnel• Already have learned recurrent talotarsal dislocation leads to an excessive amount of pronationtherefore• If we can stabilize the talus on the tarsal mechanism this should decrease the pressures/forces acting on the neurovascular structures within the tarsal tunnel.
Tarsal Tunnel Pressures- What do we know?• Neutral STJ 2 (0-7) mmHg• Maximally pronated 32 (12-60) mmHg• Pronation = significantly increases pressure within the tarsal tunnel with every step takenKumar et al: Evaluation of Various Fibro-Osseous Tunnel Pressures in Normal Human Subjects. Indian J Physiol Pharmaol, 32:139-145, 1988Trepman et al.:Effect of Foot & Ankle Position on Tarsal Tunnel Compartment Pressure. Foot Ankle Int. 20:721-726, 1999Barker et al: Pressures Changes in the Medial & Lateral Plantar and Tarsal Tunnels Related to Ankle Position: A Cadaver Study. Foot Ankle Int 28:250-254, 2007Rosson et al: Tibial Nerve Decompression in Patients with Tarsal Tunnel Syndrome: Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels. Plast Reconstr Surg 124:1202-1210, 2009
Increased Tarsal Tunnel Pressures What do we know?• A pressure of 20 – 30 mmHg has been shown to impair intraneural blood flow – Gelberman et al: Tissue Pressure Threshold for Peripheral Nerve Viability. Clin Orthop Relat Res 285-291, 1983 – Rydevik et al: Effects of graded comprssion of intraneural blood flow. An in vivo study on rabbit tibial nerve. J Hand Surg AM 6:3- 12, 1981
Overall Results 32 21 29 1834% reduction- Tarsal tunnel38% reduction- Porta pedis
Effect of Extra-Osseous TaloTarsal Stabilization on Posterior Tibial Tendon StrainJournal of Foot and Ankle Surgery, Volume 50, Issue 6 , Pages 676- 681, November 2011 • EOTTS with HyProCure decreased the elongation and strain of the posterior tibial tendon by 51%. • PTTD is a very expensive disease and no other form of treatment has shown a decreased strain on the tendon without arthrodesis and extensive hindfoot reconstructive surgery.
Cadaveric Based Research Strain Measurements - Results• Posterior Tibial Tendon – EOTTS decreased PTT strain by 51% *JFAS Nov/Dec 2011
Evaluating Plantar Fascia Strain in HyperpronatingCadaveric Feet Following an Extra-Osseous TaloTarsal Stabilization Procedure Journal of Foot and Ankle Surgery, Vol 50, No 6, Pages 682-686, November 2011 • The #1 etiology of plantar fasciitis/fasciopathy is secondary to excessive tension/strain. • EOTTS decreased that strain by 33%. • No other form of treatment has been shown to decrease the strain on the plantar fascia. • Conservative care has never been shown to decrease strain on the PF. • Surgical release of the PF leads to further weakness in the foot and eventually contributes to PTTD.
Cadaveric Based Research Strain Measurements - Results• Plantar Fascia Medial Band
Cadaveric Based Research Strain Measurements - Results• Plantar Fascia Medial Band – EOTTS decreased PF strain by 33% *JFAS Nov/Dec 2011
Cadaveric Based ResearchPressure Measurements within the Tarsal Tunnel• Therefore patients who exhibit symptomatology/pathology from their – Posterior tibial tendon – Tibialis posterior nerve – Plantar fascia – Tarsal tunnel syndrome• And have co-existing RTTD• They could benefit from the use of EOTTS.
Radiographic Evaluation of Navicular Position in the SagittalPlane – Correction Following an Extra-Osseous TaloTarsal Stabilization Procedure Journal of Foot and Ankle Surgery, Volume 50, Issue 5 Pages 551-557, September 2011 • Internal stabilization of TTD with HyProCure stabilized the medial column of the foot by preventing navicular drop. • This retrospective radiographic analysis proves the importance of stabilizing the talus and therefore decreasing the forces on the medial column of the foot.
Retrospective Radiographic Analysis• Restoration of Navicular Height following EOTTS – HyProCure.* JFAS, Vol 50, Issue 5, Pages 551-557
Retrospective Radiographic Analysis• Premise – Stabilization of talotarsal mechanism decreases anteriomedial forces – Decreased force acting on the joints anterior to the sinus tarsi – So it would be assumed that if a navicular drop was evidenced via a loss of arch height, internal stabilization of the TTM would reduce the loss of arch height.
Retrospective Radiographic Analysis• IRB Approved Study• 86 feet were evaluated in patients who had EOTTS with HyProCure ®• Pre-procedure navicular height measurements were measured and compared to post-EOTTS radiographs.
Retrospective Radiographic Analysis• EOTTS procedure maintained the normal alignment of the navicular.
Retrospective Radiographic Analysis• This proves that there is a stabilization of the medial column on the lateral column.• Decreased strain to the supporting soft tissues.• Shows that it is the osseous malformation that leads to soft tissue pathology and not vice versa otherwise stabilization of the TTM would not result in decreased strain to these supporting tissues.
Extra-Osseous Talotarsal Stabilization with HyProCure- Radiographic Outcomes in Adult Patients Journal of Foot and Ankle Surgery – Vol. 51, No. 5, p. 548-556, 2012 • EOTTS with HyProCure in adult patients as a stand-alone procedure. • 95 feet in 70 patients. • Normalization of the talar second metatarsal angle on the AP view. • Normalization of the talar declination angle on the sagittal view. • No effect on the calcaneal inclination angle. • Shows both transverse and sagittal plane correction/stabilization of the talotarsal mechanism and therefore also frontal plane correction.
EOTTS-HyProCure Analysis ®• Removal rate as a stand-alone procedure?• 7 of the 117 patients considered for this study had permanent removal- 6%• None of these patients had any long- term complications following removal.
EOTTS HyProCure Removal ®• Due to – Pain to the superficial area of the ATFL • 4 cases – Psychogenic reaction • 2 cases – Post-op infection • 1 case
Short-term Self-resolving Complications Experienced• Incision dehiscence• Prolonged skin healing• Synovitis• Period of abnormal gait• Prolonged pain and swelling
Future/On-going Prospective Studies • Prospective Functional Outcomes of EOTTS- Multi-centered study. • Gait analysis following EOTTS • Effect of EOTTS on Compression Tibialis Posterior Neuropathy
• EOTTS - it just makes sense and is becoming the gold standard.• The scientific evidence is here.• Its time we challenge the status-quo treatments
Because at the end of the day We are just trying our best to keep everyone walking.
EOTTS – HyProCure ®• Used in patients from 3 to 95 years old• Every sports activity• There has not been a single case showing a significant complication, i.e. fracture, osteomyelitis, amputation, or death.
For more information please visit: www.HyProCure.com
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