A Recent Analysis Shows Encouraging Results
Total knee arthroplasty (TKA) is undoubtedly one of the most commonly carried out surgical procedures worldwide, particularly aimed at treating patients suffering from knee osteoarthritis. Despite being so commonplace, eight to twenty-seven percent of patients experience pain after the procedure, leading to patient dissatisfaction1. This may be the consequence of soft-tissue impingements in knees with prosthetic overhang or under-coverage, implant overstuffing or over-volumetric, or patellar maltracking. To enhance patient results and satisfaction, surgeons, and manufacturers have launched several TKA innovations during the past few decades. These include patient-specific instrumentation and computer-assisted technology to better position implants and novel alignment philosophies that attempt to respect phenotypes.
Custom surgery has been on the rise due to advancements in TKA allowing for a personalized fit of the artificial joint to each patient’s specific anatomy. Usually, what happened was that a specific set of implants were present in the hospital inventory. These off-the-shelf (OTS) cannot accommodate the wide range of morphologic variation seen in anthropometric research2. Off-the-shelf TKA also has a greater percentage of implant overhang, malalignment, and aberrant kinematics3. This has increased personalized alignment’s popularity, as it has been shown to improve functional outcomes in selected patients.
Custom surgery requires the creation of a 3D model of the patient’s knee using a CT scan, which is used to manufacture a prosthetic joint tailored to the patient’s unique anatomy. This custom fit provides improved stability, range of motion, and comfort compared to traditional TKA. Personalized alignment involves adjusting the mechanical axis of the artificial joint to match the patient’s pre-operative alignment and is hypothesized to lead to improved weight bearing and joint function. This concept, however, has not been overly verified by the studies. A study published in 2019 depicted a comparable Knee Injury and Osteoarthritis Outcome Score (KOOS) for customized individually made (CIM) implants and OTS. The patient satisfaction levels were better for the CIM group, though not statistically significant3. Another analysis carried out in 2022 yielded similar results with no significant difference in patient satisfaction levels.
In other studies, the combination of custom TKA and personalized alignment has significantly increased patient satisfaction compared to traditional TKA. Recently a study published in 2023 assessed patients using by completing pre- and post-operative Patient-reported outcome measures (PROMs) using Oxford Knee Score (OKS) and Forgotten Joint Score (FJS). Proportions that attained a patient-acceptable symptom state (PASS) were calculated for OKS and FJS. The results were encouraging, and 94% of patients with a CIM implant with personalized alignment had a greater degree of satisfaction. This increased satisfaction was seen in multiple aspects of the TKA experience, including pain relief, joint stability, and overall function4.
In addition to increased patient satisfaction, custom TKA with personalized alignment has been shown to have better pain scores when compared to traditional TKA. Neginhal et al. (2020) found that custom TKA with personalized alignment led to improved knee function, reduced pain, and increased patient satisfaction compared to traditional TKA. After a median of 1.9 years of follow-up. The average pain rating decreased by 5.2 points, from a pre-op baseline of 6.5 (range, 3 to 10), to a follow-up score of 1.3. These improved clinical outcomes are likely due to the improved fit of the artificial joint and the more accurate alignment of the knee5.
While we are mentioning how CIM implants improve TKA, patient satisfaction, and clinical outcomes, it is important to note that while custom TKA with personalized alignment may provide better results, the procedure is not suitable for all patients. Patients who have significant knee deformities or complex anatomy may not be able to benefit from custom TKA with personalized alignment. However, for those who are suitable candidates, this combination provides a valuable option for achieving improved outcomes.
In conclusion, custom-made implants, themselves, haven’t made as much of an impact on patient satisfaction following knee replacement surgery with statistically insignificant differences between custom implant groups and off-the-shelf implant groups. What does translate into higher patient satisfaction is the use of personalized alignment improving nearly every patient-reported outcome measure such as joint function, reduced pain, and overall increased patient satisfaction. While the literature surrounding this topic is still a tad sparse, we can confidently say that personalized alignment should absolutely be considered for patients who are suitable candidates for TKA and seeking to have the best possible surgical outcomes.
