Patellar management in total knee arthroplasty: an educational aid

INTRODUCTION Total knee arthroplasty (TKA) is an effective and a consistently successful procedure for the treatment of patients suffering from end-stage osteoarthritis.[1] However, optimal management of the patella during TKA remains controversial in the orthopaedic community.[2,3,4] Essentially, surgeons always, never or selectively resurface the patella, based on specific patient or patellar criteria.[4] For surgeons who selectively resurface the patella, literature describes the possible indications as the presence of anterior knee pain, inflammatory arthritis, patella subluxation and maltracking, the quality of patellofemoral cartilage and patient age.[4,5] It is noted that the preference of approach depends on the location, training and personal experience of each surgeon[6]; however, surgeons should choose to resurface the patella based on the intraoperative status of the patella as well as the specific patient characteristics. Most studies from Greece indicate that surgeons do not resurface the patella during TKA,[7,8,9,10] while it is reported that surgeons in the USA and Denmark routinely resurface the patella, with the rates being more than 85%.[11,12] In England and Australia, documented patellar resurfacing rates were 33% and 48%, respectively.[12] On the contrary, Scandinavian countries, such as Norway and Sweden, revealed lower rates of patellar resurfacing, which were approximately 2%.[11,12] While the literature continues to report a wide prevalence of patellar resurfacing between 0% and >85% among different countries worldwide, it seems that a surgeon's decision to resurface the patella does not depend on evidence-based scientific factors. PATELLA RESURFACING IN TOTAL KNEE ARTHROPLASTY Studies in which surgeons choose patellar resurfacing state that resurfacing the patella could result in a lower number of reoperations and less anterior knee pain,[4] even if this was not statistically significant.[11] In a multidisciplinary symposium review, Abdel et al.[13] summarised the literature and tried to answer the question, 'To resurface or not in TKA?'. Despite the difficulty in having a clear message about the superiority or non-inferiority of resurfacing the patella, the authors also emphasised that multiple studies have shown superior stair climbing ability in patients with resurfaced patella. In the same review, the authors indicated a 10% risk of secondary resurfacing procedures in patients without a resurfaced patella.[13] Longo et al.[4] indicated that patellar resurfacing TKA performed better than those in which the patella was not resurfaced, in terms of the functional outcomes measured by the Knee Society Score and the Hospital for Special Surgery score. In addition, in a another systematic review and meta-analysis, Grela et al.[5] reported that patellar resurfacing in primary TKA is associated with reduced anterior knee pain, reoperations and complications (patellar dislocation, crepitus and clunk syndrome) [Table 1]. However, the authors presented similar patient-reported outcome measures between resurfacing and non-resurfacing groups [Figure 1].Table 1: Advantages and disadvantages.[ 2 , 5 , 14 , 15 , 16 ]Figure 1: Diagram shows the management options of the patella during total knee arthroplasty.PATELLA NON-RESURFACING IN TOTAL KNEE ARTHROPLASTY On the contrary, numerous possible complications have been reported with resurfacing the patella, such as patella fracture, component loosening, osteonecrosis, extensor mechanism disruption and persistent anterior knee pain.[13,17] Thus, advocates of non-resurfacing the patella point out the absence of obvious advantages in functional outcomes and associated complications [Table 1].[4,17] Therefore, surgeons may perform a patelloplasty, which can be defined as any reshaping of the patella performed to improve tracking in the femoral trochlea.[2] However, this definition is not specific and may comprise lateral facetectomy, patellar decompression, patella rim reshaping and resection of the damaged cartilage, osteophyte removal and/or a combination of the above procedures.[6] The current lack of standardisation hinders direct comparisons among studies. In a prospective cohort study, Lee et al.[18] reported the outcomes of patellar decompression via drilling for the treatment of anterior knee pain following TKA without patellar resurfacing. They observed significantly lower rates of anterior knee pain and no patellar complications compared to that of the untreated group. In addition, Erturk et al.,[14] in their prospective study, found that patelloplasty, including cauterisation of the patellar rim, removal of osteophytes and patellar decompression of the subchondral bone, may be a superior option in knees with grade 4 chondral lesion according to the Outerbridge classification system. Li et al.,[19] in their meta-analysis, used only five randomised controlled trials to assess anterior knee pain with and without patellar denervation in TKA and found that circumpatellar denervation was associated with improved pain and knee function, whereas complications did not differ among groups. In 2021, Qin et al.[20] completed a systematic review and meta-analysis of 12 randomised controlled trials relevant to the influence of patellar denervation on anterior knee pain and knee function following TKA. They found that patellar denervation significantly reduced the prevalence of anterior knee pain without increasing the risk of complication and revision. However, they failed to find its superiority in terms of the visual analogue score, range of motion and knee function score when compared to that of non-denervated knees after TKA [Figure 1].[20] Nowadays, partial lateral patellar facetectomy, bone resection of 10%–30% of the width, has been proposed as a new alternative treatment option with a positive influence on patellar tracking during TKA.[3,21,22] Additional indications for partial lateral facetectomy have been previously described and include patellar deformity or residual osteophytes, overhanging lateral facet leading to trochlea impingement, excessive lateral patellar tilt and patellofemoral impingement after TKA with or without patellar resurfacing.[3,22,23] Nagashima et al.[21] stated that lateral patellar facetectomy reduced the incidence of anterior knee pain in patellar-resurfaced TKA. They also found that the postoperative functional scores were significantly higher in patients treated additionally with lateral facetectomy and considered this technique as an additional manoeuvre to achieve better outcomes. In another retrospective study, Zhang et al.[22] performed lateral patellar facetectomy in patients with non-resurfacing TKA, and found improved clinical results and significant difference in anterior knee pain compared to the non-facetectomy patellar-retaining TKA group. Also, Lakstein et al.[23] examined the efficacy of lateral facetectomy in achieving good patellar tracking, as an alternative to lateral release in TKA. This study found good functional and radiographic results with no complications related to this technique. Specifically, the functional scores and anterior knee pain were comparable to that of patients with good intraoperative patellar tracking [Figure 1].[23] The option of patellectomy seems to be the last choice of treatment in certain situations including patellar fractures after TKA, recurrent patellar dislocations and advanced osteoarthritis of the patellofemoral joint.[15,16,24] Chang et al.[15] reported the outcomes of eight patients who underwent patellectomy to treat comminuted fractures after TKA. At mid-term follow-up, they found comparable results in terms of pain, compared to that achieved after the initial TKA. However, functional scores were poor in four patients, who presented with an extensor lag, and two patients had complications of quadriceps tendon and instability requiring a revision arthroplasty.[15] The same findings were reported by Hozak et al.[16] who analysed patients with patellectomy in displaced fractures after TKA.[16] They observed a decrease in the quadriceps strength at about 75%, an extensor lag between 10° and 20° and poor functional outcomes [Table 1]. The authors also concluded that patellectomy should be considered only when all previous treatments failed [Figure 1]. A possible algorithm to improve decision-making strategies regarding patellar management during TKA is summarised in Figure 2.Figure 2: Algorithm for the intraoperative patellar management during total knee arthroplasty.[ 4 , 7 , 11 , 13 ] aSeverely eroded patella, where its thickness after resection will be <12 mm, is considered not resurfacing.CONCLUSION Patellar resurfacing during TKA is still an area of considerable debate. Till now, nearly 20% of patients who underwent TKA remain unsatisfied, with anterior knee pain being one of the well-known complications after arthroplasty.[25] However, both treatment managements seem to achieve similar results, alleviating anterior knee pain and improving functional outcomes. At present, the decision to resurface the patella is based on the surgeon's philosophy, preference and training. However, it is better to make the decision at the time of surgery based on visual evidence of the patella in combination with patient's characteristics. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.