Page 41 - ISAKOS 2020 Newsletter Volume 2
P. 41

My simple interpretation of these findings is that KA certainly seems to have benefits for a substantial proportion of patients, but not all patients, and that it also seems to have some limitations that may need to be considered. It may be that those studies that were said to “adulterate” the testing of KA were simply applying these limits appropriately. Either way, I believe that the current literature is far from supporting the notion that KA is unequivocally the “best” strategy for every patient and that ongoing critical research and analysis from multiple centers is to be encouraged.
Along these lines, can we actually say that one particular alignment philosophy is the perfect one for each individual? Dr. Howell seems to firmly believe that KA is the ideal strategy, whereas others firmly believe that mechanical alignment (MA) is the ideal strategy. Can we really be this dogmatic? Or is it possible that there are different “ideal” strategies for different patients? Interestingly, in his “decision tree,” Dr. Howell actually shows that despite performing calipered cuts to match anatomy in KA, there are 6 possible scenarios in which “fine tuning” may be required, in many cases departing further from the KA concept to achieve the best result. Surely, the need for these additional options is evidence that simply performing calipered cuts to reproduce the joint line in every patient does not always produce the “best result” and that KA is a philosophy that has limitations, like many other alignment philosophies, and is not the exclusive panacea for patients who are dissatisfied after a previous TKA.
The discussion around “technological offerings such as robotics, navigation, and patient-specific instrumentation” is also interesting in that the article implies that the use of these technologies is somehow linked to MA. I think it is fair to say that these technologies are simply tools that surgeons may choose to use in order to achieve alignment more accurately, regardless of whether that alignment is achieved with KA, MA, or some other strategy. Indeed, reproducing a patient’s joint line and original anatomy may be more accurately achieved with use of improved technology around image-based navigation and anatomical analysis than with use of calipers on joints damaged by arthritis. In his closing paragraph, Dr. Howell suggests that the calipered technique is more accurate than robotics or navigation, which seems surprising, and I’m not aware of good comparative studies that have investigated this question.
Another interesting topic in the discussion is the use of a medially stabilized design. Although such a design has theoretical benefits, it is unclear why, having established excellent outcomes and survival with cruciate-retaining (CR) implants, there is a need to change implant design. No doubt there will be future studies that will carefully examine whether or not this change in implant produces the desired improvement in outcomes, but it certainly will be hard to improve on the already reported excellent outcomes.
So, are we at a point where we can say that all surgeons should use calipered KA in order to get the best result? Personally, I think that the KA philosophy is an excellent concept, and, having followed these principles myself for several years (after having used MA for many years), I am for the most part pleased with the results. I remain to be convinced that KA is the one solution for patient dissatisfaction after TKA, which we all know is multifactorial, and I do not believe that it is a “one size fits all” solution but rather a technique that has a sound scientific theoretical basis and can certainly achieve excellent results in the majority of patients. Further clarity is required around the potential limitations, particularly in patients with more abnormal anatomy, and I believe that more independent evidence is required before we can say whether it is indeed the “best” alignment philosophy for all scenarios or whether surgeons need to consider different strategies for different scenarios. Careful patient and implant selection, good surgical technique, and well-implemented rehabilitation strategies remain the cornerstone of successful outcomes. Ongoing high-quality research and critical analysis of all subsequent presentations and publications, should lead to predictable, evidence-based improvements.

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