Should the patella be resurfaced during total knee replacement?

Patellar resurfacing during total knee replacement (TKR) has been a controversial subject for many years. In 1990 a randomised prospective study was started to compare policies of resurfacing, not resurfacing and selectively resurfacing the patella. One hundred and twenty-five cases (suitable for a cruciate sparing TKR) were randomised. At the 5-year review, the group in which the patella had not been resurfaced had needed significantly more secondary surgery than the other groups. Global knee scoring systems showed little difference between the groups but a scoring system which focused on the patella revealed differences and demonstrated worse results when the patella was not resurfaced. A minor degree, of maltracking was tolerated in resurfaced knees but tended to cause pain and articular cartilage wear in unresurfaced patellae. Four knees with good patellar articular cartilage at surgery did poorly when not resurfaced, suggesting that a selective policy is not totally reliable. Routine patellar resurfacing gave the most reliable results.     

Should the patella be resurfaced at total knee replacement?

Total knee replacement (TKR) presumably is replacement of the total knee articular surface. Sometimes it is and sometimes it is not. It is this author's firm conviction that the patella should be resurfaced in the vast majority of cases. Such advocacy must be critically justified and the potential drawbacks and alternatives examined.     

Plateau–patella angle: An option for the evaluation of patellar height in patients with patellar instability

Background

Patellar instability is a debilitating disease. An important factor related to recurrent dislocation is patellar height. A new method of patellar height measurement, the plateau–patella angle (PPA), was proposed in 2011. However, to date, there is no study evaluating the use of this method in patients with patellar instability. The aim of this study was to evaluate the PPA in patients with recurrent patellar dislocation.

Oxidized zirconium versus cobalt–chromium against the native patella in total knee arthroplasty: Patellofemoral outcomes

Background

Oxidized zirconium (OxZr) has demonstrated excellent mechanical properties in vitro when used against articular cartilage; less coefficient of friction and less chondral damage have been found when compared with cobalt–chromium (CoCr) implants. However, controversy exists as to whether implants with a zirconium femoral component articulate safely with a native patella in total knee arthroplasty (TKA). To answer this question, the clinical and radiographic results were analysed from a group of patients who underwent a TKA with patella retention; the OxZr versus CoCr femoral components were compared.

Should the position of the patellar component replicate the vertical median ridge of the native patella?

Background

In total knee arthroplasty (TKA), the position of the patellar component can affect patellar tracking. However, the patellar component cannot always replicate the original high point of the patella because of anatomical variance. This study investigated whether altering the highest point of the patella can affect outcomes of primary TKA, especially in patients having a patella with a far-medialized median ridge.

Eversion or subluxation of patella in soft tissue balancing of total knee arthroplasty?: Results of a cadaver experiment

Correct postoperative leg alignment and stability of total knee prosthesis over the full range of movement are critical factors for successful TKA. This is achieved by correct implantation of prosthesis and soft tissue handling. However, the surgical approach and how to displace the patella are still controversial. We have carried out a cadaver study looking at the effect of patella eversion or subluxation on limb axis alignment during balancing of the knee in three different standard surgical approaches; subvastus, midvastus, or medial parapatellar. For each approach, five knees were studied. Leg alignment was visualised by the Ci CT-free DePuy/BrainLAB navigation system. Using a navigation system alignment was determined in the AP axis in both extension and 90 flexion, with the patella everted as well as subluxated. Eversion of the patella gave a more valgus axis reading than subluxation in both extension 0.58 (SD: 0.03, range 0.54 -0.60 ) and 90 flexion 0.48 (SD: 0.11, range 0.38 -0.60 ). The effect was greatest using the medial paraptellar approach. Surgeons should be aware that everting the patella influences the AP alignment when soft tissue balancing in total knee replacement.     

LCS mobile bearing total knee arthroplasty without patellar resurfacing. Does the unresurfaced patella affect outcome? Survivorship at a minimum 10-year follow-up

BackgroundPatellar resurfacing during total knee arthroplasty (TKA) remains controversial. The aim of this study was to evaluate the long-term outcomes of a mobile-bearing TKA without patellar resurfacing.MethodsWe assessed the outcomes in 503 patients (600 knees) who had cemented LCS (low contact stress) mobile bearing TKA without patellar resurfacing at a minimum follow-up of 10 years. Clinical outcome scores and radiological assessment were used.ResultsFour knees were revised, two had bearing dislocation and nine patients (1.5%) had secondary resurfacing for anterior knee pain. There were no radiolucent lines or osteolytic defects on radiographic evaluation.The overall survivorship was 97.8% with re-operation for any reason as the endpoint.ConclusionNon-resurfacing of the patella does not adversely affect the outcome of the LCS mobile bearing TKA at minimum 10 years follow-up.     

Patella related problems as common reason for revision of NexGen PS® total knee arthroplasty without patella resurfacing: An analysis of 5911 primary total knee arthroplasties registered in the Dutch Arthroplasty Register

BackgroundPatella resurfacing remains controversial in primary total knee arthroplasty (TKA). The aim of this study was to investigate if there was a difference in revision rate and reason for revision within 8 years after single brand primary cemented TKA with or without patella resurfacing, using data from the Dutch Arthroplasty Register.MethodsAll primary TKA surgeries with a posterior stabilized cemented primary NexGen®, between 2010 and 2013 with diagnosis osteoarthritis were analyzed (n = 5911). Multivariate cox regression analyses were performed to analyze differences in revision rate between TKA with or without patella component, and was adjusted for age and previous surgery.ResultsOf 5911 TKA surgeries, 4795 were performed without patella resurfacing (81.1%) and 1116 with patella resurfacing (18.9%). There was a significant difference in patellar problems as reason for revision between patients after primary TKA with patella resurfacing (9.3%) and without patella resurfacing (29.9%) (p = 0.01). This was mostly caused by patellar pain (28.0%). There was no significant difference in cumulative revision rate within between TKA with patella resurfacing and without patella resurfacing.ConclusionIn conclusion, 30% of patients who need revision surgery after TKA using NexGen® PS without patella resurfacing the reason for revision is patella related problems, compared to 9% after TKA NexGen® PS with patella resurfacing. There was no difference in cumulative incidence of revision after primary surgery of all TKA’s using NexGen® PS with or without patella. To reduce the probability of reoperation for patella related problems, our data suggest the patella should be resurface during primary TKA.