Hintegra Total Ankle System

51 Hintegra Total Ankle System


Beat Hintermann and Roxa Ruiz


Abstract


The Hintegra ankle is a three-component ankle that uses a flat, 4-mm-thick loading plate with six pyramidal peaks for full coverage of resection surface of tibia. The talar component is anatomically shaped with a conical form with a smaller radius medially rather than laterally. It has two 2.5-mm rims on the medial and lateral sides which ensure stable position of the polyethylene insert. The insert is available with the thickness of 5 to 9 mm. Given the parallelism of the two interfaces, the Hintegra ankle does provide, in contrast to other current ankles, intrinsic stability in the frontal plane. Its unique design permits to use the Hintegra ankle as a part of hindfoot reconstruction, which may also include correcting osteotomies above and below the ankle, fusion of periarticular joints, ligament reconstructions, and tendon transfers. It also allows to revise a failed ankle arthrodesis to total ankle replacement. With the available revision components with thicker tibial platform and flat talar undersurface, respectively, the Hintegra ankle also enables the surgeon to manage bone defects, as typically encountered in revision of failed component. Conceptor and nonconceptor studies have proven effectiveness of the Hintegra ankle in the clinical use with a survivor-ship of 86 to 93% at 10 years.


Keywords: total ankle replacement, Hintegra ankle, surgical technique, indication, contraindication, design, revision arthroplasty


51.1 Introduction


• In the past decade, total ankle replacement has evolved to a valuable alternative to arthrodesis for end-stage osteoarthritis of the ankle.


• The Hintegra ankle is composed of three components and was introduced in 2000 to the market (not yet approved by the Food and Drug Administration for U.S. market).


• Numerous studies have reported very satisfactory outcomes with a survivorship of 86 to 93% at 1 year.


51.2 Indications


• Primary and secondary end-stage osteoarthritis of the ankle.


• Salvage of failed ankles.


• Salvage for failed ankle fusions.


• Low and moderate demands for sports.


• Associated hindfoot or midfoot arthritis, bilateral ankle arthritis.


• Patient not wanting an ankle fusion.


51.2.1 Clinical Evaluation


While the patient is standing, perform a thorough clinical investigation of both lower extremities to assess


• Alignment.


• Deformities.


• Foot position.


• Muscular atrophy.


While the patient is sitting with free-hanging feet, perform an assessment of


• Extent to which a present deformity is correctable.


• Preserved joint motion at the ankle and subtalar joints.


• Ligament stability of the ankle and subtalar joints with anterior drawer and tilt tests.


• Supination and eversion power (e.g., function of posterior tibial and peroneus brevis muscles).


51.2.2 Radiographic Evaluation


• Standard weight-bearing X-rays including alignment view (Fig. 51.1).


• CT scan to assess bone stock.


• SPECT-CT to assess neighboring joints.


• MRI to assess vascularity.


51.2.3 Nonoperative Options


• Brace immobilization.


• Activity modification.


• Rocker bottom sole and cushioned heel to shoe; orthotic inserts.


• Medications: cortisone injection, hyaluronic acid injections, anti-inflammatory medications.


51.2.4 Contraindications


Relative

• Severe osteoporosis.


• Immunosuppressive therapy.


• Increased demands for physical activities (e.g., jogging, tennis, downhill skiing).


Absolute

• Infection.


• Avascular necrosis of more than one-third of surface at either talar or tibial side.


• Nonmanageable instability/misalignment.


• Neuromuscular disorders.


• Charcot neuroarthropathy.


• Metal allergy or intolerance.


• Highest demands for sports.


51.3 Goals of Surgical Procedure


• To replace the worn-out articular surfaces of tibia and talus with minimal bone resection.


• To restore mechanics of the ankle as closely as possible.


• To mimic physiologic load transfer at bone–implant interface and thus ensure for long-term stability of components.



51.4 Advantages of Surgical Procedure


• Simple and reliable instrumentation.


• Nonconstrained three-component device.


• Includes revision implants.


51.5 Key Principles


• Anterior approach to the ankle.


• Mounting and adjusting tibial resection bloc, tibial cut.


• Step-by-step talar resection.


• Debridement of medial, lateral, and posterior gutters.


• Insertion of implants:


image Talar component.


image Tibial component.


image Polyethylene insert.


• Additional procedures, if necessary:


image To align the ankle joint complex.


image To stabilize the ankle joint complex.


• Wound closure.


51.6 Preoperative Preparation and Patient Positioning


51.6.1 The Device (Fig. 51.2)


• Design of tibial component:


image Maximal contact area.


image Physiological load transfer.



• Design of talar component:


image Anatomically shaped


image Guides the polyethylene insert


• Design of polyethylene insert:


image Covers talus completely.


image Optimal force distribution.


image Minimal deformation forces.


• Resurfacing alone:


image Minimal bone resection.


image Minimal disturbance of vascularity.


image No stress shielding.


• Minimal thickness:


image Minimal stress forces.


image Minimal dislocation.


51.6.2 Anatomy


• The superior extensor retinaculum is a thickening of the deep fascia above the ankle, running from the tibia to the fibula including the tendons of the tibialis anterior, extensor hallucis longus, and extensor digitorum longus.


• The anterior neurovascular bundle lies consistently between the extensor hallucis longus and extensor digitorum longus tendons.


• The neurovascular bundle contains the tibialis anterior and the deep peroneal nerve.


51.6.3 Positioning


• The patient is positioned with the feet on the edge of the table.


• The ipsilateral back is lifted until a strictly upward position of the foot is obtained.


• The tourniquet is mounted at the ipsilateral thigh.


51.7 Operative Technique


51.7.1 Exposure


• An anterior longitudinal incision of 10 to 12 cm in length is made to expose the retinaculum.


• The retinaculum is incised along the lateral border of the anterior tibial tendon.


• The distal tibia is exposed, and arthrotomy is made.


• Loose bodies and osteophytes are removed.


• The Hintermann distractor is mounted on anteromedial side to distract the ankle joint (Fig. 51.3a).


51.7.2 Tibial Resection (Fig. 51.3b, c)


• The tibial cutting block with its alignment rod is positioned using the tibial tuberosity as the proximal reference, and the anterolateral border of the ankle as the distal reference.


• The final adjustment is made as follows:


image Sagittal plane: The rod is moved until a position parallel to the anterior border of the tibia has been achieved.


image Frontal (coronal) plane: After preliminary fixation of the block with a long pin, the tibial resection block is rotated until proper varus/valgus alignment and ligament tension have been achieved.


image Vertical adjustment: The tibial resection block is moved proximally until the desired resection height is achieved. Usually, resection of approximately 2 mm on the apex of the tibial plafond is desired.


• The tibial cutting guide is slid into the cutting block, creating a slot in which the saw blade will be guided. The width of the slot limits the excursion of the saw blade, thereby protecting the malleoli from being hit and fractured.


• Tibial cut is done with an oscillating saw.


51.7.3 Talar Resection


• The talar resection block is inserted into the tibial cutting block.


• The resection block is moved distally as much as possible to properly tension the collateral ligaments.


• While the foot is held in neutral position, the resection block is fixed by two pins.


• Talar cut is done with an oscillating saw.


• The 12-mm-thick spacer, representing the thickness of the tibial and talar components and the thinnest 5-mm inlay, is inserted into the created joint space. While the foot is held in neutral flexion position, the surgeon should check (Fig. 51.3d):


image If an appropriate amount of bone has been resected.


image If the achieved alignment is appropriate (Fig. 51.3e).


image If the medial stability and lateral stability are appropriate.


• The spacer is removed and the Hintermann distractor mounted using the same pins.


Jul 19, 2019 | Posted by in SPORT MEDICINE | Comments Off on Hintegra Total Ankle System
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