Total Ankle Arthroplasty. Joseph P. McCormick, M.D. Affinity Orthopedics & Sports Medicine the original 2014

Transcription

1 Total Ankle Arthroplasty Joseph P. McCormick, M.D. Affinity Orthopedics & Sports Medicine the original 2014

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3 Ankle Anatomy The ankle is a hinge or ginglymus joint Made up of the tibia, fibula, & talus Bordered medially by the medial malleolus Bordered laterally by the fibula

4 Ankle Anatomy The subtalar (or talocalcaneal) joint is beneath the tibiotalar articulation Interacts with the ankle joint in providing motion Especially useful in eversion & inversion Accommodation on uneven surfaces

5 Ligamentous Ankle Anatomy Tibiotalar/Subtalar Deltoid (medial) 3 ligaments (lateral) Interosseous talocalcaneal ligament Syndesmotic ligaments

6 Ankle Anatomy Ankle mortise The key to understanding the ankle in function A well-aligned mortise represents ankle alignment, fibular length, intact plafond, syndesmotic stability, talar congruity, and intact ligaments Perpendicular alignment to the tibia is critical

7 Total Ankle Arthroplasty! We could be in the middle of a revolution in surgical management of the ankle! This is probably an exaggeration Arthrodesis has long been the primary surgical intervention for symptomatic arthritis Are the scales now tipping toward TAA as the best treatment for end-stage arthritis?

8 What About Total Ankle Arthoplasty? TAA is in evolution Arthrodesis has traditionally offered good patient satisfaction, pain relief, clinical outcomes However, 1.7 procedures to achieve fusion Ipsilateral hindfoot arthritis can develop Poor ROM Gait abnormalities

9 Total Ankle Arthoplasty? TAA was introduced in the early 1970 s Progressive development in implant design, surgical technique, clinical outcomes, and survivorship Arthrodesis is stable from TAA is increased 57% over that period!

10 The Mystery of TAA Why has TAA puzzled orthopedics? Large body forces concentrated on small components First-generation designs required revision or fusion with rates of 72% at 10 years These were constrained (i.e. hinged designs) All-poly tibial components (older poly designs) Cemented Cementless fixation is considered better by most

11 The Mystery of TAA As failure rates diminish, the demand for TAA by younger, more active patients likely will increase Remember, 70% required revision or fusion by 10 years, and now 70+% survival is seen at 10 years! Therefore, it is in the interests of orthopedists to evaluate & understand the outcomes of current TAAs

12 Total Ankle Arthoplasty Early designs were infamous for high early failure rates Non-anatomic designs Highly constrained designs Excessive bone resection Current designs reveal 71-77% survivorship over 10 years Modern meta-analysis of 58 studies found 89% at 10 years (Zaidi et al JBJS, 2013)

13 Total Ankle Arthoplasty Can TAA achieve the same success as hip, knee and shoulder arthroplasties? Many believe it will Collaborative large-scale RCTs will be needed Joint registries Systematic reviews Time will tell

14 Ankle Biomechanics Deformity plays a large rate-limiter in TAA Tibiotalar deformities in RA or post-trauma Gutter adhesions Ligamentous instability Hindfoot deformity Surgical technique and infection risk (RA, DM, and age-related risks)

15 Ankle Biomechanics Contraindications Vascular impairment Severe joint laxity Compromised soft tissue envelope Neuropathy Avascular necrosis of the talus

16 Ankle Biomechanics Limited talar bone mass is the reality Body weight is applied (and increased) during weight-bearing on this very small surface area Talar component subsidence and avascular problems remain a source of concern

17 Ankle Arthroplasty Anterior approach Lateral approach is gaining popularity Non-cemented implants Fixed bearing but unconstrained Mobile bearing 6 weeks non-weighted, then gradually advance activities Usually unlimited lo-impact after another month

18 DePuy Agility Syndesmotic fusion design Titanium alloy Available since 2007 Fusion above predicted the best outcomes

19 DePuy Agility Frank G. Alvine, M.D. Over 800 implanted Syndesmotic fusion (within 6 months) is key Tibial components which loosen prematurely have delayed fusions at the syndesmosis ~10% revision rate at ten years (Saltzman et al., JBJS(A), 2007) Multiple revisions since introduction

20 STAR Prosthesis Small Bone Innovations The Scandinavian Total Ankle Replacement Mobile bearing middle poly segment Titanium alloy Poly is centered in a groove through the midportion

21 STAR Prosthesis The mobile-bearing design rationale Mobile design dissipates rotational, translational, and shear forces This is turn lowers the forces at the bone/prosthetic interface At 24 months, excellent results and 100% survival in US trial (Mann et al., Foot Ankle Int, 2009) The well-known authors continue to tout >90% survival at 10 years

22 Inbone System Wright Medical Highly modular Titanium alloy Utilizes the intramedullary alignment of the tibia

23 Inbone System A longer talar component can be used for subtalar fusion as well This system is generally accepted as a failsafe for TAA failures Lengthy tibial or talar fixation remove stresses from close to the articular load, extend them to diaphysis Long term data is anecdotal on this device

24 Salto Talaris System Tornier, Inc French design Evolved in Europe into both fixed-bearing & mobile bearing designs Talar component uses size specific curvature radii

25 Salto Talaris System Only the fixed-bearing version became US approved (2006) This 3 piece design has shown very little detrimental movement (tight tolerances) 96% survival at 2.8 years (Schweitzer et al., JBJS(A), Much more European data available, although this is extrapolated mobile bearing design work: 85% survival at 8.9 years (Bonnin et al., CORR, 2010)

26 Trabecular Metal Ankle Zimmer Porous tantalum Lateral approach, with fibular repair required Extensive jig for deformity correction and limited resection of bone

27 Trabecular Metal Ankle Tantalum (Ta) has a close relationship to Titanium (Ti) Revolutionizing bone prosthetic interface development over it s 15 years in production Most US companies are developing similar design

28 Trabecular Metal Ankle Ta ankle implants are promising for talar and tibial components in their fixedbearing design Lateral approach is slightly easier with less soft tissue damage, relying on deltoid tensioning alone, and facilitating use of the jig system

29 Final, Final TAA is in it s childhood (not infancy) US data is rapidly accumulating 10 year data seems quite good Likely easy candidates are sedentary & normal BMI with minimal deformity More challenging cases are increasing deformity, high BMI, and worse yet younger age Absolute negatives are per neuropathy, infection and soft tissue compromise

30 Thank You!