EOTTS is a procedure that uses an internal fixation device to stabilize the talus bone and prevent excessive motion on the calcaneus and navicular bones. It is differentiated from inter-osseous and intra-osseous procedures by being purely soft tissue based. Research shows EOTTS reduces abnormal forces on structures like the posterior tibial tendon and plantar fascia by over 50% by restoring normal talo-tarsal joint motion. Cadaver studies prove EOTTS stabilizes talus positioning and decreases pressures in the tarsal tunnel that can cause neuropathy. Clinical studies show EOTTS improves function and reduces pain for patients with recurrent talo-tarsal dislocations.

1. Michael E. Graham, DPM, FACFAS
Macomb, Michigan
Long Version

2. • What is EOTTS?
• Rationale/Indications for an EOTTS
procedure
• Evidence Base
– Cadaveric Research
– Clinical Research
• Conclusions

3. 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.

4. When would/should you recommend
EOTTS to your patients?

5. 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).

6. 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.

7. Normal TaloTarsal Motion
• Supination
• Pronation
• Normal strain is placed on the
supporting structures.
• Articular facets of TTM remain in
constant congruent contact.
• Efficient machine

8. 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”.

9. 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.

10. Radiographic Evaluation
NORMAL Weightbearing Lateral View
• Talar Declination Angle
< 26 degrees
• Cyma line
• Sinus tarsi “open”

11. 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.

12. 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.

13. Radiographic Evaluation
ABNORMAL-Weightbearing AP View
• Talar 2nd Met. Angle
>16 degrees
• Transverse plane
dislocation deformity

14. Radiographic Evaluation
ABNORMAL – Weightbearing Lateral View
• Talar Declination > 26 degrees
• Anterior deviated Cyma line
• Obliterated sinus tarsi
• Sagittal plane dislocation deformity

15. Comparison of NP-TTM vs RSP
Evidence for Recurrent Talotarsal Dislocation

16. Comparison of NP-TTM vs RSP
Evidence for Recurrent Talotarsal Dislocation

17. Clinical Evidence of Recurrent
TaloTarsal Dislocation

18. 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.

19. 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.

20. 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.

21. Type I:
Subtalar Joint Arthroereisis
The goal is to stop the
anterior progression of
lateral process by some
method within the outer
half of the sinus tarsi.
Arthroereisis
implants act sole
within the lateral
half of the tarsal
sinus.

22. Subtalar Joint Arthroereisis
• This technique is focused on limiting or blocking
the lateral process of the talus.
Plantar view of talus

23. Function – Type I
• This device
acts/acted as an
anterior extension of
the lateral process of
the talus.

24. 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.

25. 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.

26. Type I Subtalar Arthroereisis
• Unfortunately, the new designs did little to
decrease the overall removal rate.
• Reported rates from 38% to 100% removal

27. Type II: Non-arthroereisis
Extra-Osseous TaloTarsal
Stabilization with HyProCure.

28. Type I – arthroereisis implants
limits/blocks talar motion here.
Type II- HyProCure stabilizes
the talotarsal mechanism here.
HyProCure
is not an arthroereisis device.

29. TYPE I
The leading edge of TYPE II
arthroereisis devices HyProCure
come into contact internally stabilizes
with the calcaneus the talus at the
here. cruciate pivot point
here.
Top view of the calcaneus
Type II does not block or limit motion.

30. Normal amount of pronation and
supination is still available with
Type II device.
(There is a limitation of motion with Type I)

31. HyProCure stabilizes the talus at
the cruciate pivot point to restore
the talotarsal axis of motion back
to normal.

32. • Cadaveric Based
• Retrospective Clinical Findings
• Prospective Clinical Analysis

33. 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

34. 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

35. Stabilization of Joint Forces of the Subtalar
Complex via the HyProCure Sinus Tarsi Stent
Journal 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.

36. 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.

37. 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.

38. EOTTS Cadaver Study

39. 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

40. Talocalcaneal Articulations after
EOTTS

41. 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

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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.

48. Effect of Extra-Osseous TaloTarsal Stabilization on
Posterior 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.

49. 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

50. 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

51. 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

52. 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

53. Cadaveric Based Research
Strain Measurements - Results
• Tibialis Posterior Nerve
– EOTTS decreased TPN strain by 43%
*JFAS Nov/Dec 2011

54. Cadaveric Based Research
Pressure 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.

55. Cadaveric Based Research
Pressure Measurements within the Tarsal Tunnel
• Already have learned recurrent talotarsal
dislocation leads to an excessive amount
of pronation
therefore
• 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.

56. 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 taken
Kumar et al: Evaluation of Various Fibro-Osseous Tunnel Pressures in Normal Human
Subjects. Indian J Physiol Pharmaol, 32:139-145, 1988
Trepman et al.:Effect of Foot & Ankle Position on Tarsal Tunnel Compartment Pressure.
Foot Ankle Int. 20:721-726, 1999
Barker 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, 2007
Rosson 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

57. 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

58. Overall Results
32 21 29 18
34% reduction- Tarsal tunnel
38% reduction- Porta pedis

59. Effect of Extra-Osseous TaloTarsal Stabilization on
Posterior Tibial Tendon Strain
Journal 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.

60. Cadaveric Based Research
Strain Measurements - Results
• Posterior Tibial Tendon
– EOTTS decreased PTT strain by 51%
*JFAS Nov/Dec 2011

61. Evaluating Plantar Fascia Strain in Hyperpronating
Cadaveric 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.

62. Cadaveric Based Research
Strain Measurements - Results
• Plantar Fascia Medial Band

63. Cadaveric Based Research
Strain Measurements - Results
• Plantar Fascia Medial Band
– EOTTS decreased PF strain by 33%
*JFAS Nov/Dec 2011

64. Cadaveric Based Research
Pressure 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.

65. Radiographic Evaluation of Navicular Position in the Sagittal
Plane – 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.

66. Retrospective Radiographic Analysis
• Restoration of Navicular Height
following EOTTS – HyProCure.
* JFAS, Vol 50, Issue 5, Pages 551-557

67. 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.

68. 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.

69. Retrospective Radiographic Analysis
• EOTTS procedure maintained the
normal alignment of the navicular.

70. 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.

71. 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.

72. 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.

73. EOTTS HyProCure Removal ®
• Due to
– Pain to the superficial area of the ATFL
• 4 cases
– Psychogenic reaction
• 2 cases
– Post-op infection
• 1 case

74. Short-term Self-resolving
Complications Experienced
• Incision dehiscence
• Prolonged skin healing
• Synovitis
• Period of abnormal gait
• Prolonged pain and swelling

75. 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

76. • EOTTS - it just makes sense and is
becoming the gold standard.
• The scientific evidence is here.
• Its time we challenge the status-quo
treatments

77. Because at the end of the day
We are just trying our best
to keep everyone walking.

78. 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.

79. For more information please visit:
www.HyProCure.com

80. Thank you.