Candace Lightner, of MicroPort Orthopaedics, discusses surgical techniques and developments in the total knee replacement market
Total knee arthroplasty has revolutionised the treatment of end-stage knee arthritis, providing relief for individuals suffering from severe pain and limited mobility. While experts widely recognize the procedure’s success in restoring function and enhancing quality of life, a disconcerting element persists: approximately 20% of patients express dissatisfaction with the results [1].
This disparity underscores the need to explore advancements in surgical techniques and alignment approaches to address patients’ concerns and improve overall satisfaction. Recent developments in the total knee replacement market have focused more on implant selection, favouring medially stabilised designs, as well as alternative alignment choices to restore joint line and stability, aiming to create a knee that not only relieves pain and restores function but also feels more natural.
Among the emerging strategies, the combination of a medial-pivot style implant paired with a kinematic alignment approach has gained popularity for its ability to enhance patient outcomes. By examining the principles and benefits of this approach, along with recent advancements in the field, orthopaedic professionals can gain insights into the growing trend of restoring normal anatomy and kinematics in knee arthroplasty, as well as understand the factors that drive patients to seek out these specific implant and alignment techniques.
Evolving trends in the total knee replacement market
In recent years, a considerable transformation has taken place in the total knee replacement market, with a growing interest in the medial-pivot philosophy. The medial-pivot knee design is intended to mimic the natural kinematics of the knee, incorporating a medial side that is concave in shape and a lateral side that is less constrained, allowing for a more mobile lateral compartment. These features create a knee that is more stable on the medial side than lateral, resembling a ball-in-socket type joint in the medial compartment and allowing for more lateral translation. This concept, which has been in existence for over 25 years, is gaining popularity as more surgeons and patients recognise its numerous benefits.
Initially considered a niche or boutique option, medial-pivot implants differed from traditional knee designs that featured a J-curve femoral component. True medial-pivot implants are characterised by a constant radius femoral component with a more concave medial compartment on the tibia, creating a highly conforming ball-in-socket design that aims to replicate the knee’s natural kinematics. This design principle is based on the understanding that the knee is inherently stable medially and more mobile laterally.
Traditional J-curve knee designs rely on different design features to provide stability of the joint. However, we know many patients complain of a loss of stability after total knee replacement and are still unsatisfied with their results. These traditional implants have been categorized as either cruciate retaining (CR), where the patient’s PCL remains intact, or posterior stabilised (PS), which features a post-and-cam mechanism to replace the patient’s PCL. And while these designs have shown great success for the last several decades, medial-pivot style implants are growing in popularity and offer a promising solution