Review Question - QID 218196

This rheumatic patient demonstrates advanced knee osteoarthritis with notable varus deformity and medial tibial plateau erosion. Given her age, medical comorbidities, and incompetent medial/posterior collateral ligaments (MCL/PCL), she would be most appropriately treated utilizing a rotating hinged total knee arthroplasty (Answer 5).

Early hinged total knee arthroplasty (TKA) designs had notoriously high revision rates due to aseptic loosening. To decrease the stress transferred to the implant/bone interface, a rotating polyethylene design was introduced, resulting in a precipitous drop in revision rates. These novel rotating hinged implants with improved long-term sustainability expanded the indications for use to include: oncologic reconstruction, complex revision TKA, periprosthetic fracture management, genu recurvatum (>5 degrees), and gross mismatch between flexion and extension gaps (commonly seen in rheumatoid arthritis). Further, rotating hinged implants may be used in the primary TKA setting in low functional demand, elderly patients with notable bone loss or collateral ligament deficiency (i.e. this patient presentation).

Jones and colleagues performed a retrospective review of two early cohort studies in which rotating hinged designs were utilized (which were considered novel implants at that time) over non-rotating hinged implants. They reported improved range of motion and functional outcomes scores in all patients without any mechanical failures at the final follow-up (mean = 3 years). The authors concluded that orthopaedic surgeons should have confidence in utilizing the rotating hinged TKA system when confronted with complex and/or salvage knee arthroplasty.

Hernández-Vaquero and Sandoval-García performed a retrospective review of their 26-patient cohort in which rotating hinged implants were utilized for collateral ligamentous deficiency. At a minimum follow-up of two years, all patients demonstrated improved range of motion and functional outcome scores with three revisions due to non-mechanical reasons (i.e. periprosthetic infection or periprosthetic fracture). The authors concluded that rotating hinged TKA can provide substantial improvement in function and reduction in pain when utilized in elderly or sedentary patients with severe ligamentous deficiencies.

Cottino and colleagues retrospectively reviewed the long-term outcomes of their institution’s utilization of rotating-hinged components for nononcologic indications. They identified 408 patients with 18% indicated for complex primary cases and 82% for revision cases. All patients had significantly improved Knee Society scores with a cumulative incidence of all-cause revisions being 9.7% at 2 years and 22.5% at 10 years. They further found lower revision rates for aseptic loosening when metaphyseal cones were utilized. The authors concluded that contemporary rotating-hinge TKA implants are durable constructs with good long-term outcomes.

Figure A demonstrates this patient’s knee with notable varus deformity, medial tibial plateau erosion, and advanced arthritic changes. Illustrations A&B demonstrate their post-operative images in which a primary rotating hinged implant was utilized (although without metaphyseal cones).

Incorrect Answers:
Answer 1: Unicompartmental arthroplasty is indicated for individuals who demonstrate predominantly single-compartment arthritic disease. This patient has global arthritic changes and a chronic varus deformity.
Answer 2, 3 & 4: Given this patient’s age and medical comorbidities (i.e. rheumatoid arthritis), implants should be cemented to prevent loosening in her likely osteopenic/osteoporotic bone. Similarly, an MCL reconstruction would not be appropriate in a low functional demand, elderly rheumatic patient where the risk for failure is high. However, press-fit components, MCL reconstruction, and utilizing constrained non-hinged implants could be considered in younger, healthier patients.