Abstract
It is a not so uncommon clinical scenario: well-fixed, well-aligned, balanced total knee arthroplasty with continued pain. However, radiographs also demonstrate an unresurfaced patella. The debate continues and the controversy remains as whether or not to routinely resurface the patella in total knee arthroplasty. In perhaps the most widely referenced article on the topic, the overall revision rates were no different between the resurfaced (9%) and the unresurfaced (12%) groups and thus their conclusion was that similar results can be obtained with and without resurfacing. However, a deeper look in to the data in this study shows that 4 times more knees in the unresurfaced group were revised for patellofemoral problems.
A more recent study concluded that selectively not resurfacing the patella provided similar results when compared to routinely resurfacing. The study does emphasise however, that this conclusion depends greatly on femoral component design and operative diagnoses. This suggests that selective resurfacing with a so-called “patella friendly” femoral component in cases of tibio-femoral osteoarthritis, is a safe and effective strategy. Finally, registry data would support routine resurfacing with a 2.3 times higher relative risk of revision seen in the unresurfaced TKA. Regardless of which side of the debate one lies, the not so uncommon clinical scenario remains; what do we do with the painful TKA with an unresurfaced patella.
Precise and accurate diagnosis of the etiology of a painful TKA can be very difficult, and there is likely a strong bias towards early revision with secondary patellar resurfacing in the painful TKA with an unresurfaced TKA. At first glance, secondary resurfacing is associated with relatively poor outcomes. Correia, et al. reported that only half the patients underwent revision TKA with secondary resurfacing had resolution of their complaints. Similarly, only 53% of patients in another series were satisfied with the procedure and pain relief. The conclusions that can be drawn from these studies and others are that either routine patellar resurfacing should be performed in all TKA or, perhaps more importantly, we need to better understand the etiology of pain in an otherwise well-aligned, well-balanced, well-fixed TKA.
It is this author's contingency that the presence of an unresurfaced patella leads surgeons to reoperate earlier, without truly identifying the etiology of pain or dissatisfaction. This strong bias; basically there is something more that can be done, therefore we should do it, is the same bias that leads to early revision of partial knee arthroplasty. While very difficult, we as knee surgeons should not revise a partial knee or secondarily resurface a patella due to pain or dissatisfaction. Doing so, unfortunately, only works about half the time.
The diagnostic algorithm for evaluating the painful, uresurfaced TKA includes routinely ruling out infection with serum markers and an aspiration. Pre-arthroplasty radiographs should be obtained to confirm suitability and severity of disease for an arthroplasty. An intra-articular diagnostic injection with Marcaine +/− corticosteroid should provide significant pain relief. MARS MRI may be beneficial to evaluate edema within the patella. Lastly, operative implant stickers to confirm implant manufacturer and type are critical as some implants perform less favorably with unresurfaced patellae. To date, no studies of secondary resurfacing describe the results of this, or similar, algorithms for defining patellofemoral problems in the unresurfaced TKA and therefore it is still difficult to conclude that poor results are not simply due to our inherent bias towards early revision and secondary resurfacing of the unresurfaced patella.
