This document discusses the history and design of ankle replacement implants. It describes the evolution from first-generation constrained implants requiring extensive bone resection to current third-generation semi-constrained implants with three components. Fixed-bearing and mobile-bearing designs are compared, along with factors in determining candidacy, surgical technique, outcomes, and complications of total ankle replacement.

1. Ankle replacement
Dr. Sairamakrishnan S

2. • Since the first report of total ankle
arthroplasty in the 1970s, more than 20 total
ankle arthroplasty systems have been
introduced
• The first-generation, cemented, constrained
designs were very stable but required
extensive bony resection for implantation and
frequently failed because of loosening and
extensive osteolysis.

3. • Second-generation, less constrained implants
required less bone resection and did not require
cement fixation; because shear forces and torsion
at the bone-prosthesis were reduced, loosening
was less frequent.
• However, increased polyethylene wear and
failure compromised the stability of the
components, often leading to painful
impingement and subluxation or complete
dislocation of the components.

4. • Contemporary, third-generation,
semiconstrained total ankle systems consist of
three components:
– a metallic baseplate that is fixed to the tibia,
– a domed or condylar-shaped metallic component
that resurfaces the talus,
– an ultrahigh-molecular-weight polyethylene
bearing surface interposed between the tibial and
talar components.

5. • Systems in which the polyethylene component
is locked into the baseplate often are referred
to as “two-piece” or “fixed-bearing” designs,
whereas those with the polyethylene
component not attached to the baseplate are
called “three-piece” or mobile or meniscal
bearing systems

6. • Anatomic problems
– (1) the ankle has significantly less contact area
between joint surfaces than the hip or knee;
– (2) the ankle experiences 5.5 times body weight
with normal ambulation, compared with 3 times
body weight at the knee; and
– (3) the articular cartilage surface of the ankle is
uniformly thinner than that of the knee.

7. FIXED-BEARING VERSUS MOBILE-
BEARING DESIGN
• Based on movement between the poly and
the tibial component
• “forgiveness” of the implant, which allows
small variances in alignment to be
compensated for by a reorientation of the
prosthesis to accommodate the joint forces.

8. • Proponents of fixed-bearing designs suggest
that the normal ankle joint, as opposed to the
knee, has a more stable central axis of motion
and less need for an additional degree of
freedom of motion.
• Backside polyethylene wear against the tibial
component is a major concern with mobile-
bearing designs and less with fixed designs.

10. ALIGNMENT
• The most common method of obtaining
correct alignment is an external alignment jig,
using intraoperative fluoroscopy to judge the
alignment.

11. PREOPERATIVE EVALUATION
• Systemic diseases such as diabetes,
inflammatory arthritis, chronic obstructive
pulmonary disease, and peripheral vascular or
heart disease, active smoking may adversely
affect the outcome and healing of the incision.
• Conditions such as sleep apnea, malnutrition,
vitamin D deficiency, and depression are
associated with decreased functional
outcomes and poor results.

12. • Adjacent joint problems should be addressed
first
• Clinical assessment of the gastrocsoleus
complex and the Achilles tendon is important.
• The skin should be stable and without lesions
that would impair the healing of the surgical
incision.

13. • Minimum, standing radiographs of the ankle
in anteroposterior, lateral, and mortise views
should be obtained.

14. INDICATIONS
• The ideal candidate for ankle arthroplasty has
been described as an older, thin, low-demand
individual with minimal deformity and
retained ankle range of motion.

15. • Commonly cited contraindications to total ankle
arthroplasty
– age younger than 50 years
– history of poor patient compliance
– heavy industrial laborer
– heavy smoker
– uncontrolled diabetes with neuropathy
– significant ankle instability
– Angular deformity of more than 10 to 15 degrees
– vascular insufficiency
– obesity (over 250 lb),
– significant bone loss, osteonecrosis
– active or previous infection.

16. TOTAL ANKLE ARTHROPLASTY OR ANKLE
ARTHRODESIS FOR ANKLE ARTHRITIS

18. SPECIAL CIRCUMSTANCES
• Inflammatory arthritis
• Obesity
• Diabetes
• Pantalar disease; concomitant hindfoot
arthrodesis
• Takedown of ankle arthrodesis

19. OUTCOMES
• Overall revision rates according to registry
databases have been cited as 21.8% at 5 years
and 43.5% at 10 years.
• In general, those with a fixed-bearing implant
had more improvements in ankle moment and
ground reaction forces, whereas those with
mobile-bearing implants had more
improvement in patient-reported pain.

20. COMPLICATIONS
• Wound healing complications
• Osteolysis, loosening, and subsidence
• Malalignment
• Fracture
• Infection
• Deep venous thrombosis
• Heterotopic ossification
• Progression of arthritis in adjacent joints
• Osteophyte formation/impingement