Archives of Orthopaedic and Trauma Surgery | 2021
The dissatisfied total knee arthroplasty patient. New technologies-the white knight in shining armor coming to their rescue?
Abstract
Knee osteoarthritis (OA) and its prosthetic treatment went through a major evolution over the last 40 years since its inception. From a procedure, where patients signed initially two consent forms; one for total knee arthroplasty (TKA) followed by a plaster cast immobilization and a second for a mobilization under anesthesia (MUA) a few weeks later to start bending again, TKA became today a procedure performed in ambulatory surgery centers (ASC) with patients walking out on the same day [1]. The drive behind all of this has always been, from the start, the wish of surgeons to obtain the best possible results for their patients after joint replacement. This ambition became clear when the “Forgotten Joint Score” was developed [2]. A knee-specific score, evaluating in a very detailed way, how aware patients are about their arthritic knee before [3] and after kneeand hip arthroplasty [2, 4]. Today, still around 20 percent of TKA patients are dissatisfied with their procedure, substantially more than after hip replacement. Orthopedic surgeons and implant producers often wish to reduce this dissatisfaction to a surgically solvable problem and therefore limited to a purely mechanical cause. They might neglect well-known issues such as the preoperative absence of bone on bone OA, pre-existing risk factors for acute and chronic pain, chronic morphine use, central pain sensitization, inflammatory neuropathy around the knee, pain catastrophizing, referred pain, workman compensation and many other psychosocial factors [5, 6]. For surgeons and the orthopedic industry, these unsatisfied patients remain the reason for their continuous quest to do better by research and development, leading to different innovations trying to solve these problems. In the past two decades, the TKA patient’ dissatisfaction was explained by sizing issues leading to overhang and pain or downsizing and flexion instability. This led to the development of many different sizes with more representative anatomical aspect ratios and better surface matching. The next attempt to solve dissatisfaction came with the introduction of more partial knee replacements, where resurfacing of only the diseased side of the knee would lead to better results. Indications, expertise with surgical technique, the balance between quicker recovery and a more natural feeling of the knee versus a threefold higher revision rate seem to be limiting factors to convince all surgeons in favor of unicompartmental knee arthroplasty (UKA). Furthermore, a maximum 50% of all patients might be treated with UKA, including statistics from high volume centers. And now lately, we are observing a trend towards personalized alignment. Each human being has its own unique type of alignment, developed during his lifetime and approaching this native alignment more closely, would lead to a better outcome. The ambition of surgeons to start implanting knee arthroplasties in their more oblique native joint line position is not new and as any re-invention of an old failed philosophy, comes with a new engineered technological solution, such as precision-enabling robots today. Hungerford and Krackow developed this oblique alignment philosophy 40 years ago as anatomical alignment (AA), with a fixed 3° femoral valgus and 3° tibial varus in the coronal plane and a femoral component aligned parallel to the posterior condylar axis (PCA) in the axial plane. They observed unfortunately alignment outliers due to the limitations of their simple instrumentation and failure of the Porous Coated Anatomic-implant [7]. As a reaction, mechanical alignment (MA) as proposed by Insall, became the gold standard to equally load the polyethylene on both sides and to avoid important component position outliers Antonio Klasan is an editorial board member of Archives of Orthopaedic and Trauma Surgery and is an associate editor for BMC Musculoskeletal Disorders.