New Jersey Low Contact Stress Total Ankle Replacement: Biomechanical Rationale and Review of 23 Cementless Cases

Abstract

A congruent contact, unconstrained, multiaxial ankle replacement has been developed for use without cement. A talar onlay component with a trochlear surface and central fixation fin uses a cylindrical articulating axis that reproduces the lateral talar curvature. A tibial inlay component with a 7 degree anteriorly inclined short fixation stem uses a flat loading plate, recessed anatomically into the distal tibia to distribute tibial loads to the ankle joint. For both components, made of cast cobalt-chromium-molybdenum, a 275-micron pore-size, sintered-bead, porous coating is used to allow tissue ingrowth stabilization. A congruent ultra-high molecular weight polyethylene bearing is inserted between the metallic implants. Its upper surface is flat, whereas its lower surface conforms to the trochlear surface, thereby providing unconstrained, sliding cylindrical motion with low contact stress on the bearing surfaces. Contact pressure and collateral ligaments maintain ankle stability during both static and dynamic loading conditions. Clinically, 23 total ankle arthroplasties were performed in 21 patients. The follow-up period ranged from 24 months to 64 months with a mean of 35.3 months. Diagnoses included rheumatoid arthritis, 6 patients (26.1%); osteoarthritis, 4 patients (17.4%); post-traumatic arthritis, 10 patients (43.5%); avascular necrosis of the talus, 2 patients (8.7%), and painful ankle fusion, 1 patient (4.3%). Pain was the primary reason for surgery in all cases. Postoperatively, 87% of ankles had no pain or, at most, mild pain. Postoperative complications included poor wound healing in four ankles, reflex sympathetic dystrophy in two ankles, deep infection in one ankle, and one bearing subluxation. No ankle replacements were removed and no fusions were performed for failed implants, although one bearing was exchanged without disrupting the metallic elements. In this report, the suggestion is made that total ankle arthroplasty may have an improved application in various arthritis disorders when used with biologic fixation and unconstrained mobile bearings.

Which Are the Most Frequently Used Outcome Instruments in Studies on Total Ankle Arthroplasty?

“…2 This graph shows the distribution of the outcome instruments used among the TAA studies in this review. AOFAS = American Orthopaedic Foot and Ankle Society hindfoot score (region-specific) [21]; VAS pain = visual analog scale pain; SF-36 = Short Form 36 (generic) [43]; NJOH = New Jersey Orthopaedic Hospital ankle score (region-specific) [5]; Evanski = outcome instrument of Evanski and Waugh [11]; Takakura = outcome instrument of Takakura et al [39]; Mazur = outcome instrument of Mazur et al [29]; FFI = Foot Function Index (region-specific) [3]; AOS = Ankle Osteoarthritis Scale (disease-specific) [9]; MFA = Musculoskeletal Functional Assessment (generic) [10]; UCLA = University of California at Los Angeles activity scale (physical activity assessing) [31]; ''Oxford'' = questionnaire (region-specific) developed by the authors [18], modeled to the original Oxford Hip Score [7]; IPAQ = International Physical Activity Questionnaire (physical activity assessing) [31]; HAQ = Health Assessment Questionnaire (generic) [12]. [4]; AOS = Ankle Osteoarthritis Scale [9]; ICC = intraclass correlation coefficient; total = total score; pain = pain subscale; limit = limitations subscale; disab = disability subscale.…”

Metabolic cost and mechanical work for the step-to-step transition in walking after successful total ankle arthroplasty

“…The control group consisted of 11 healthy participants without any impairment of the lower extremities. Inclusion criteria for the TAA group were: a primary diagnosis of osteoarthritis or rheumatoid arthritis of the ankle joint; a good clinical outcome as defined by ankle scores of more than 80 points 6 on both the Low Contact Stress (LCS) ankle score (Buechel, Pappas, & Iorio, 1988) and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score (Kitaoka et al, 1994). Furthermore, alignment of the ankle-hindfoot complex should be neutral and range-of-motion, as measured by manual goniometry, should be a minimum of 10 degrees of dorsiflexion and 20 degrees of plantarflexion.…”

Long-Term Effectiveness of Cementless Shallow-sulcus and Deep-sulcus Mobile-Bearing Total Ankle Replacements: 2 Case Reports with over 20 years Follow-up

“…The first report is a 29 year follow-up of the first cementless mobile-bearing shallow-sulcus device developed by the authors in 1978 [11]. The second report describes the improved deep-sulcus device [12] developed in 1989 which has functioned well for 22 years in this patient.…”