Strategy regarding patella resurfacing in total knee replacement (TKR) remains controversial. TKR revision rates are reportedly influenced by surgeon procedure volume. The study aim was to compare revision outcomes of TKR with and without patella resurfacing in different surgeon volume groups using data from the AOANJRR. The study population included 571,149 primary TKRs for osteoarthritis. Surgeons were classified as low, medium, or high-volume based on the quartiles of mean primary TKR volume between 2011 and 2020. Cumulative percent revision (CPR) using Kaplan-Meier estimates of survivorship were calculated for the three surgeon volume groups with and without patella resurfacing. Cox proportional hazards models, adjusted for age and sex, were used to compare revision risks. High-volume surgeons who did not resurface the patella had the highest all-cause CPR (20-year CPR 10.9%, 95% CI [10.0%, 12.0%]). When the patella was resurfaced, high-volume surgeons had the lowest revision rate (7.3%, 95% CI [6.4%, 8.4%]). When the high-volume groups were compared there was a higher rate of revision for the non-resurfaced group after 6 months. When the medium-volume surgeon groups were compared, not resurfacing the patella also was associated with a higher rate of revision after 3 months. The low-volume comparisons showed an initial higher rate of revision with patella resurfacing, but there was no difference after 3 months. When only patella revisions were considered, there were higher rates of revision in all three volume groups where the patella was not resurfaced. TKR performed by high and medium-volume surgeons without patella resurfacing had higher revision rates compared to when the patella was resurfaced. Resurfacing the patella in the primary procedure protected against revision for patella reasons in all surgeon volume groups. Level of evidence: III (National registry analysis)

Resurfacing the patella is performed the majority of the time in the United States and in many regions it is considered standard practice. In many countries, however, the patella is left un-resurfaced an equal amount of the time or even rarely ever resurfaced. Patella resurfacing is not a simple or benign procedure. There are numerous negative sequelae of resurfacing including loosening, fragmentation, avascular necrosis, lateral facet pain, stress fracture, acute fracture, late fracture, and restricted motion. In a study by Berend, Ritter, et al, failures of the patella component were reported 4.2% of the time at an average of only 2.6 years. A study was undertaken at Washington University in recent years to determine rather more clinical problems were observed following total knee replacement with or without patella resurfacing. Records were maintained on all problem total knees cases with well localised anterior knee pain. The referral area for this clinic is St. Louis which is among the largest American cities, with the highest percentage of total knees that are performed without patella resurfacing. During 4 years of referrals of total knee patients with anterior knee pain, 47 cases were identified of which 36 had a resurfaced patella and 11 had a non-resurfaced patella. Eight of 36 resurfaced patellae underwent surgery while only 2 of 11 non-resurfaced patellae underwent subsequent surgery. More than 3 times as many painful total knees that were referred for evaluation had already had their patella resurfaced. In spite of the fact that approximately equal number of total knees were performed in this area without patella resurfacing, far more patients presented to clinic with painful total knee in which the patella had been resurfaced. The numerous pathologies requiring a treatment following patella resurfacing included patella loosening, fragmentation of the patella, avascular necrosis patella, late stress fracture, lateral facet pain, oblique resurfacing, and too thick of a patellar composite. In a large multi-center randomised clinical trial at 5 years from the United Kingdom in over 1700 knees from 34 centers and 116 surgeons, there was no difference in the Oxford Score, SF-12, EQ-5D, or need for further surgery or complications. The authors concluded, “We see no difference in any score, if there is a difference, it is too small to be of any clinical significance”. In a prospective of randomised clinical trial performed at Tulane University over 20 years ago, no differences were observed in knee score, a functional patella questionnaire, or the incidence of anterior knee pain between resurfaced and un-resurfaced patellae at time intervals of 2–4 years, 5–7 years, or greater than 10 years. Beyond 10 years the knee scores of total knee patients with a resurfaced patella had declined significantly greater than those with a non-resurfaced patella. There are numerous advantages of not resurfacing the patella including less surgical time, less expense, a lower risk of “major” complications (especially late complications), and if symptoms develop in an un-resurfaced patella, it is an easier salvage situation with more options available. A small percentage of total knee patients will be symptomatic whether or not their patella is resurfaced. Not resurfacing the patella retains more options and has fewer complications. The major determinant of clinical result and the presence of anterior knee pain after knee replacement is surgical technique and component design not whether or not the patella is resurfaced. Patella resurfacing is occasionally necessary for patients with inflammatory arthritis, a deformed or maltracking patella, or symptoms and pathology that are virtually restricted to the patellofemoral joint. For the vast majority of patients, however, patella resurfacing is not necessary

Resurfacing the patella is performed the majority of the time in the US and in many regions it is considered standard practice. In many countries, however, the patella is left unresurfaced an equal amount of the time or even rarely ever resurfaced. Patella resurfacing is not a simple or benign procedure. There are numerous negative sequelae of resurfacing including loosening, fragmentation, avascular necrosis, lateral facet pain, stress fracture, acute fracture, late fracture, and restricted motion. In a study by Berend, Ritter, et al, failures of the patella component were reported 4.2% of the time at an average of only 2.6 years. A study was undertaken at Washington University in recent years to determine whether more clinical problems were observed following total knee replacement with or without patella resurfacing. Records were maintained on all problem total knees cases with well localised anterior knee pain. The referral area for this clinic is St. Louis which is among the largest American cities, with the highest percentage of total knees that are performed without patella resurfacing. During 4 years of referrals of total knee patients with anterior knee pain, 47 cases were identified of which 36 had a resurfaced patella and 11 had a non-resurfaced patella. Eight of 36 resurfaced patellae underwent surgery while only 2 of 11 non-resurfaced patellae underwent subsequent surgery. More than 3 times as many painful total knees that were referred for evaluation had already had their patella resurfaced. In spite of the fact that approximately equal number of total knees were performed in this area without patella resurfacing, far more patients presented to clinic with painful total knee in which the patella had been resurfaced. The numerous pathologies requiring a treatment following patella resurfacing included patella loosening, fragmentation of the patella, avascular necrosis patella, late stress fracture, lateral facet pain, oblique resurfacing, and too thick of a patellar composite. In a large multi-center randomised clinical trial at 5 years from the United Kingdom in over 1700 knees from 34 centers and 116 surgeons, there was no difference in the Oxford Score, SF-12, EQ-5D, or need for further surgery or complications. The authors concluded, “We see no difference in any score, if there is a difference, it is too small to be of any clinical significance”. In a prospective randomised clinical trial performed at Tulane University over 20 years ago, no differences were observed in knee score, a functional patella questionnaire, or the incidence of anterior knee pain between resurfaced and unresurfaced patellae at time intervals of 2–4 years, 5–7 years, or greater than 10 years. Beyond 10 years the knee scores of total knee patients with a resurfaced patella had declined significantly greater than those with a non-resurfaced patella. There are numerous advantages of not resurfacing the patella including less surgical time, less expense, a lower risk of “major” complications (especially late complications), and if symptoms develop in an unresurfaced patella, it is an easier salvage situation with more options available. A small percentage of total knee patients will be symptomatic whether or not their patella is resurfaced. Not resurfacing the patella retains more options and has fewer complications. The major determinant of clinical result and the presence of anterior knee pain after knee replacement is surgical technique and component design not whether or not the patella is resurfaced. Patella resurfacing is occasionally necessary for patients with inflammatory arthritis, a deformed or maltracking patella, or symptoms and pathology that are virtually restricted to the patellofemoral joint. For the vast majority of patients, however, patella resurfacing is not necessary

OBJECTIVES. The use of a mobile bearing has been suggested to decrease the rate of patellar complications after total knee arthroplasty (TKA). However, to resurface or retain the native patella remains debated. Few long-term results have been documented. The present retrospective study was designed to evaluate the long-term (more than 10 years) results of mobile bearing TKAs on a national scale, and to compare pain results and survivorship according to the status of the patella. The primary hypothesis of this study was that the 10 year survival rate of mobile bearing TKAs with patella resurfacing will be different from that of mobile bearing TKAs with native patella retaining. METHODS. All patients operated on between 2001 and 2004 in all participating centers for implantation of a TKA (whatever design used) were eligible for this study. Usual demographic and peri-operative items have been recorded. All patients were contacted after the 10 year follow-up for repeat clinical examination (Knee Society score (KSS), Oxford knee questionnaire). Patients who did not return were interviewed by phone call. For patients lost of follow-up, family or general practitioner was contacted to obtain relevant information about prosthesis survival. TKAs with resurfaced patella and TKAs with retained native patella were paired according to age, gender, body mass index and severity of the coronal deformation (with steps of 5°). Pain score, KSS and Oxford knee score were compared between two groups with a Student t-test at a 0.05 level of significance. Survival curve was plotted according to the actuarial technique, using the revision for mechanical reason as end-point. The influence of the patella status was assessed with a logrank test at a 0.05 level of significance. RESULTS. 1,604 TKAs were implanted during the study time-frame. 849 cases could be paired according to age, gender, BMI and severity of the pre-operative coronal deformation (2/1 ratio) into two groups: resurfaced patella (496 cases) and retained patella (243 cases). There was no difference in any baseline criteria between both groups. 150 patients deceased before the 10 year follow up (18%). Final follow-up was obtained for 489 cases (58%). 31 reoperations (prosthesis exchange or patellofemoral revision) were performed during the study time frame (4%), with 17 reoperations for mechanical reasons (3%). KSS and Oxford knee score were significantly higher for TKAs without patella resurfacing, there was a significant difference between the 13 year survival rates of TKAs with resurfaced patella (97%) and TKAs with retained native patella (93%). CONCLUSIONS. The primary hypothesis was confirmed: 10 year survival rate of mobile bearing TKAs with patella resurfacing was better than mobile bearing TKAs with native patella retaining. Patella resurfacing may lead to a better survival after mobile bearing TKA. However, the clinical results were better after patella resurfacing when the index TKA was not revised

Aim. The aim of the study was to assess the impact of a self aligning unidirectional mobile tibial bearing and the use of a patella button on lateral patella release rates within a knee system using a common femoral component for both the fixed and mobile variants. Methods and results. A total of 347 patients undergoing TKR were included in the study and randomly allocated to receive either a Mobile Bearing (171 knees) or a Fixed Bearing (176 knees) PS PFC Sigma TKR. Further sub-randomisation into patella resurfacing or retention was performed for both designs. The need for lateral patella release was assessed during surgery using the ‘no thumbs’ technique. The lateral release rate was similar for fixed bearing (9.65%) and mobile bearing (9.94%) implants (p=0.963). Patella resurfacing resulted in lower lateral release rates when compared to patella retention (5.8% vs 13.8%; p=0.0131). This difference was most marked in the mobile bearing group where the lateral release rate was 16.3% with patella retention compared to 3.5% with patella resurfacing (p=0.005). Conclusion. The addition of a rotating platform tibial component had no impact on the lateral release rate in this study. Optimising patella geometry by patella resurfacing appears more important than tibial bearing deisgn per se. The combination of a mobile bearing design and patella resurfacing appears to optimise the lateral release rate and patello-femoral tracking in the PS PFC Sigma design which has a deeply radiused trochlea on the femoral component. The results with a patella resurfacing confirm the results with this prosthesis reported by Pagnano et al in Clin Orthop 428 pp221-227

Deep infection is a devastating complication of total knee arthroplasty (TKA). This study aimed to determine if there was a relationship between surgeon volume and the incidence of revision for infection after primary TKA. Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 1 September 1999 to 31 December 2020 for primary TKA for osteoarthritis that were revised for infection. Surgeon volume was defined by the number of primary TKA procedures performed by the surgeon in the year the primary TKA was performed and grouped as <25, 25-49, 50-74, 75-99, >100 primary TKA procedures per year. Kaplan Meir estimates for cumulative percent revision (CPR) and Cox Proportional Hazard Ratios were performed to compare rates of revision for infection by surgeon volume, with sub-analyses for patella and polyethylene use, age <65 years and male gender. 5295 of 602,919 primary TKA for osteoarthritis were revised for infection. High volume surgeons (>100 TKA/year) had a significantly lower rate of revision for infection with a CPR at 1 and 17 years of 0.4% (95% CI 0.3, 0.4) and 1.5% (95% CI 1.2, 2.0), respectively, compared with 0.6% (95% CI 0.5, 0.7) and 2.1% (95% CI 1.8, 2.3), respectively, for low volume surgeons (<25 TKR/year). Differences between the high-volume group and the remaining groups remained when sub-analysis for age, gender, ASA, BMI, patella resurfacing and the use of cross-linked polyethylene (XLPE). High volume surgeons have lower rates of revision for infection in primary TKA

BACKGROUND. Patella resurfacing in TKA remains controversial. The purpose of this study was to compare the long-term clinical outcome in TKA in patients undergoing bilateral TKAs with one patella resurfaced and the other patella nonresurfaced. METHODS. Twenty-nine patients (58 knees) underwent primary bilateral TKA for osteoarthritis. These patients were enrolled in a prospective randomised double blinded study and represent a subset of a larger study of patella resurfacing. All patients received the same posterior cruciate sparing TKA. Patients each had one knee randomised to treatment with or without patella resurfacing. The contralateral knee then received the alternative patellar treatment, such that all patients had one knee with a resurfaced patella and the other nonresurfaced. Clinical evaluations consisted of routine radiographic and clinical follow-up and included with a Knee Society Score patellofemoral specific patient questionnaire. Twenty-eight patients (56 knees) participated and were followed for a mean of 118 months (range, 69–146 months). RESULTS. There were no significant differences between the knees treated with and without patellar resurfacing with regard to range of motion, KSCRS, or the pain and function scores. Forty-six percent (13/28 patients) of patients preferred the resurfaced knee, 36% (10/28) the nonresurfaced knee, and 18% (5/28) had no preference. Two patients (7%) in the nonresurfaced group required revision for a patellofemoral related complication, compared to one patient (3.5%) in the group with a resurfaced patella. CONCLUSIONS. Ten year follow-up reveals equivalent results for resurfaced and nonresurfaced patellae in TKA with regards to ROM, KSCRS, pain and function, or patellofemoral symptoms. In this large series of bilateral TKAs, 64% of patients either preferred the unresurfaced knee or had no preference

The aim of this retrospective cohort study was to investigate the reasons for total knee arthroplasty (TKA) revisions at a tertiary hospital over a four-year period. The study aimed to identify the primary causes of TKA revisions and shed light on the implications for patient care and outcomes. The study included 31 patients who underwent revisions after primary knee arthroplasty between January 2017 and December 2020. A retrospective approach was employed, utilizing medical records and radiological findings to identify the reasons for TKA revisions. The study excluded oncology patients to focus on non-oncologic indications for revision surgeries. Patient demographics, including age and gender, were recorded. Data analysis involved categorizing the reasons for revision based on clinical assessments and radiological evidence. Among the 31 patients included in the study, 9 were males and 22 were females. The age of the patients ranged from 43 to 81, with a median age of 65 and an interquartile range of 18.5. The primary reasons for TKA revisions were identified as aseptic loosening (10 cases) and prosthetic joint infection (PJI) (13 cases). Additional reasons included revision from surgitech hemicap (1 case), patella osteoarthritis (1 case), stiffness (2 cases), patella maltracking (2 cases), periprosthetic fracture (1 case), and patella resurfacing (1 case). The findings of this retrospective cohort study highlight aseptic loosening and PJI as the leading causes of TKA revisions in the examined patient population. These results emphasize the importance of optimizing surgical techniques, implant selection, and infection control measures to reduce the incidence of TKA revisions. Future research efforts should focus on preventive strategies to enhance patient outcomes and mitigate the need for revision surgeries in TKA procedures

This study aimed to analyze the effect of two different techniques of cement application: cement on bone surface (CoB) versus cement on bone surface and implant surface (CoBaI) on the short-term effect of radiolucent lines (RLL) in primary fully cemented total knee arthroplasties (TKA) with patella resurfacing. 379 fully cemented TKAs (318 patients) were included in this monocentric study. Preoperative and postoperative at week 4 and 12 month after surgery all patients had a clinical and radiological examination and were administered the Oxford Knee Score (OKS). Cement was applied in two different ways among the two study groups: cement on bone surface (CoB group) or cement on bone surface and implant surface (CoBaI group). The evaluation of the presence of RLL or osteolysis was done as previously described using the updated Knee Society Radiographic Evaluation System. The mean OKS and range of motion improved significantly in both groups at the 4-week and 12-month follow-up, with no significant difference between the groups (CoB vs. CoBaI). RLL were present in 4.7% in the whole study population and were significantly higher in the CoBaI group (10.5%) at the 4-week follow-up. At the 12-month follow-up RLL were seen in 29.8% of the TKAs in the CoBaI group, whereas the incidence was lower in the CoB group (24.0% (n.s.)). There were two revisions in each group. None of these due to aseptic loosening. Our study indicated that the application of bone cement on bone surface only might be more beneficial than onto the bone surface and onto the implant surface as well in respect to the short-term presence of RLL in fully cemented primary TKA. The long-term results will be of interest, especially in respect to aseptic loosening and might guide future directions of bone cement applications in TKA

Joint registries suggest a downward trend in the use of uncemented Total Knee Replacements (TKR) since 2003, largely related to reports of early failures of uncemented tibial and patella components. Advancements in uncemented design such as trabecular metal may improve outcomes, but there is a scarcity of high-quality data from randomised trials. 319 patients <75 years of age were randomised to either cemented or uncemented TKR implanted using computer navigation. Patellae were resurfaced in all patients. Patient outcome scores, re-operations and radiographic analysis of radiolucent lines were compared. Two year follow up was available for 287 patients (144 cemented vs 143 uncemented). There was no difference in operative time between groups, 73.7 v 71.1 mins (p= 0.08). There were no statistical differences in outcome scores at 2 years, Oxford knee score 42.5 vs 41.8 (p=0.35), International Knee Society 84.6 vs 84.0 (p=0.76), Forgotten Joint Score 66.7 vs 66.4 (p=0.91). There were two revisions, both for infection one in each group (0.33%). 13 cemented and 8 uncemented knees underwent re-operation, the majority of these being manipulation under anaesthetic (85.7%), with no difference (8.3% vs 5.3%, 95% CI -2.81% to 8.89%, p = 0.31). No difference was found in radiographic analysis at 2 years, 1 lucent line was seen in the cemented group and 3 in the uncemented group (0.67% v 2.09%, 95%CI -4.1% to 1.24%, p = 0.29). We found no difference in clinical or radiographic outcomes between cemented and uncemented TKR including routine patella resurfacing at two years. Early results suggest there is no difference between cemented and uncemented TKR at 2 years with reference to survivorship, patient outcomes and radiological parameters

Whether to resurface the patella during a primary Total Knee Replacement (TKR) performed as a treatment of degenerative osteoarthritis remain a controversial issue. Patellar resurfacing was introduced because early implants were not designed to accommodate the native patella in an anatomic fashion during the range of motion. Complications related to patella resurfacing became a primary concern and have been associated with the variable revision rates often report post TKR. Subsequent modifications in implant design have been made to offer the surgeon option of leaving the patella un-resurfaced. Numerous clinical trials have been done to determine the superiority of each option. Unfortunately, there is little consensus and surgeon preference remains the primary variable. One of the major reasons given to support patella resurfacing is to eliminate Anterior Knee Pain post operatively. However, studies have shown that this problem was not exclusively found in non-resurfaced patients so the author conclude that anterior knee pain is probably related to component design or to the details of the surgical technique, such as component rotation rather that whether or not the patella is resurfaced. An increasing rate of complications with the extensor mechanism after patellar resurfacing led to the concept of selective resurfacing of the patella in TKR. Decision making algorithms with basis of clinical, radiographic and intraoperative parameters have been developed to determine which patients are suitable for patella resurfacing and which are suitable for patella non-resurfacing. Finally, the continued study of this topic with longer follow up term in randomized, controlled, clinical trials remains essential in our understanding of patella in TKR. The development of joint registry will allow surgeons to draw conclusions on the basis of larger numbers of patients and will improve the reporting of the results of patellar non resurfacing in clinical trials. In general, surgeons in United States always resurface while their counterparts in Europe tend to never resurface

Aims. The aim of this study was to assess the incidence the microbiological spectrum and clinical outcome of hip and knee revision arthroplasties with unexpected-positive-intraoperative-cultures (UPIC) at a single center with minimum follow up of 2 years. Methods. We retrospectively analyzed our prospectively maintained institutional arthroplasty registry. Between 2011 and 2020 we performed presumably aseptic rTHA (n=939) and rTKA (n= 1,058). Clinical outcome, re-revision rates and causes as well as the microbiological spectrum were evaluated. Results. In total, 219/939 (23.3%) rTHA and 114/ 1,058 (10.8%) rTKA had a UPIC (p<0.001). Single positive intraoperative cultures were found in 173/219 (78.9%) in rTHA and 99/114 (86.8%) in rTKA, whereas 46/219 (21.0%) rTHA and 15/114 (13.2%) rTKA had positive results in ≥2 intraoperative cultures. A total of 390 microorganisms were found among the 333 cases. Staphylococcus epidermidis 30.9%, CoNS (21.9%), Cutibacterium acnes 21.1%, and Bacillus spp. 7.3% were the most common microorganisms. Overall, detected microorganisms showed high sensitivity to daptomycin (96.6%), vancomycin (97.3%) and linezolid (98.0%). After a minimum follow up of 2 years (rTHA 1,470 (735; 3,738) days; rTKA 1,474 (749; 4,055) days). During the 2-year follow-up, 8 patients died and 5 were lost to follow-up. There were 54/219 (24.7%) re-revision in rTHa and 20/114 (17.5%) in rTKA. Overall, there were 23 (10.5%) septic re-rTHA and 9 (7.9%) septic re-rTKA as well as 31 (14.2%) aseptic re-rTHA and 11 (9.6%) aseptic re-rTKA. Patients with previous septic revisions bevor UPIC procedure showed a significant higher risk for septic re-revision (p<0.05). Moreover, there were less septic re-revisions after single culture positive UPIC (rTHA: 16/173 (9.2%); rTKA 6/99 (6.1%)) compared to ≥2 positive intraoperative cultures UPIC (rTHA: 7/46 (15.2%); rTKA 3/15 (20.0%)). The most common reason for re-revision in the rTHA-group was aseptic loosening of the cup (34.2%) or of the stem (23.3%), dislocation (18.3%) and periprosthetic-fractures (7.8%). In the rTKA-group it was aseptic loosening (40.4%), instability (24.6%) and secondary patella resurfacing (7.9%). There was a higher septic re-revision rate in consecutive revisions than in planned revisions 17.3% vs. 8.5% in the rTHA-group and 14.3% vs. 7.5% in the rTKA-group, p<0.001. Conclusion. UPICs are common in rTJA. The rate was higher in hips which may partly explained by the easier pre op joint aspiration in the knee. UPIC may lead to an increase in subsequent re-revisions

Introduction. Unidirectional mobile bearing knees (RP) were developed to optimise the tibio-femoral articulation in an effort to enhance function and reduce polyethylene wear. The self-aligning bearing should also benefit the patello-femoral joint further improving outcome. This study was designed to assess whether these potential benefits are realised in the clinical setting. Methods. A total of 352 patients undergoing a PS PFC Sigma TKR were randomly allocated to receive either a Mobile Bearing (176 knees) or a Fixed Bearing (176 knees) tibial tray. Within each group a further randomisation for patella resurfacing versus retention was included. All knees were scored using standard outcome tools (Oxford, AKSS, Patella Score) by independent nurse specialists. Results. At 5 year review there had been 38 deaths (19 in each group), 5 revisions (4 fixed, 1 RP), 7 late patella resurfacings (4 fixed, 3 RP) and a small number of other patients had withdrawn, leaving 142 fixed bearing knees and 144 mobile bearing knees for evaluation. The rotating platform TKR design had no impact on range of motion, Oxford Knee Score and American Knee Society knee and function scores when compared to its fixed bearing equivalent at minimum 5 year follow-up. Patella resurfacing, however, resulted in a greater improvement in knee function score from pre-op when compared to patella retention (25.5 vs 15.5, p=0.0015), with subsequent significant benefits seen in the SF-12 Physical and Total Scores (p=0.0004 and p=0.017 respectively). 5 year survivorship curves with revision for any cause as the endpoint were similar for both groups (fixed 96.2%, mobile 97.6%). This survivorship rises to 100% for both designs when considering aseptic loosening alone. Conclusion. There was no difference in performance between the fixed and RP groups. Patella resurfacing offered advantages over patella retention with this design and we would recommend its routine use

Background. The management of the patella during primary total knee arthroplasty (TKA) is controversial. Despite the majority of patients reporting excellent outcomes following TKA, a common complaint is anterior knee pain. Resurfacing of the patella at the time of initial surgery has been proposed as a means of preventing anterior knee pain, however current evidence, including four recent meta-analyses, has failed to show clear superiority of patellar resurfacing. Therefore, the purpose of this study was to estimate the cost-effectiveness of patellar resurfacing compared to non-resurfacing in TKA. Methods. We conducted a cost-effectiveness analysis using a decision analytic model to represent a hypothetical patient cohort undergoing primary TKA. Each patient will receive a TKA either with the Patella Resurfaced or Not Resurfaced. Following surgery, patients can transition to one of three chronic health states: 1) Well Post-operative, 2) Patellofemoral Pain (PFP), or 3) Serious Adverse Event (AE), which we have defined as any event requiring Revision TKA, including: loosening/lysis, infection, instability, or fracture (Figure 1). We obtained revision rates following TKA for both resurfaced and unresurfaced cohorts using data from the 2014 Australian Registry. This data was chosen due to similarities between Australian and North American practice patterns and patient demographics, as well as the availability of longer term follow up data, up to 14 years postoperative. Our effectiveness outcome for the model was the quality-adjusted life year (QALY). We used utility scores obtained from the literature to calculate QALYs for each health state. Direct procedure costs were obtained from our institution's case costing department, and the billing fees for each procedure. We estimated cost-effectiveness from a Canadian publicly funded health care system perspective. All costs and quality of life outcomes were discounted at a rate of 5%. All costs are presented in 2015 Canadian dollars. Results. Our cost-effectiveness analysis suggests that TKA with patella resurfacing is a dominant procedure. Patients who receive primary TKA with non-resurfaced patella had higher associated costs over the first 14 years postoperative ($16,182 vs $15,720), and slightly lower quality of life (5.37 QALYs vs 6.01 QALYs). The revision rate for patellar resurfacing was 1.3%. If the rate of secondary resurfacing procedures is 0.5% or less, there is no difference in costs between the two procedures. Discussion. Our results suggest that, up to 14 years postoperative, resurfacing the patella in primary TKA is cost-effective compared to primary TKA without patellar resurfacing, due to the higher revision rate in this cohort of patients for secondary resurfacing. Our sensitivity analysis suggests that, among surgical practices that do not routinely perform secondary resurfacing procedures (estimated rate at our institution is 0.3%) there is no significant difference in costs. Although our results suggest that patella resurfacing results in higher quality of life, our model is limited by the availability and validity of utility outcome estimates reported in the literature for the long term follow up of patients following TKA with or without patella resurfacing and secondary resurfacing procedures

Objective. We performed total knee arthroplasty (TKA) without patella resurfacing in patients with osteoarthritis (OA) of the knee. The purpose of the present study was to evaluate the clinical results and the appropriateness TKA without patella resurfacing. Methods. A total of 61 patients (61 affected knees) who had undergone a Low Contact Stress mobile − bearing knee arthroplasty (LCS− TKA) (Depuy, Warsaw, IN. USA) 10 years or more before the present study were enrolled. The LCS− TKAs did not include patella resurfacing. The patients' mean age was 77.7 ± 6.1 years (range: 59−94 years). The mean follow-up period was 121 ± 2.4 months (range: 120−129 months). The clinical evaluation used the scoring system for OA of the knees issued by the Japanese Orthopaedic Association (JOA score). We defined patellofemoral (PF) pain, crepitation, patellar clunk syndrome, spin-out, and reoperation as complications. We also used X-Ray imaging to measure the component angle, patella height, lateral shift ratio, tilting angle, femorotibial angle, posterior condylar offset and joint line, and evaluated the localization of sclerotic changes in the patella. All of the LCS− TKAs were performed by one surgeon using the midvastus approach. During the operation, the osteophyte around the patella was resected, and the osteophyte on the articular surface was shaped using a bone saw. For statistical analysis we performed Mann-Whitney's U test and adopted a significance level of P<5%. Results. The average JOA score improved significantly from 46.2 ± 10.4 before the LCS− TKA to 82.6 ± 6.1 after the LCS− TKAs (P = 0.0002). No cases of patellar clunk syndrome or spin-out. occurred. Revision surgery was performed for two cases, one involved an infection, and the other involved a patella fracture. Postoperative PF pain was found in 6 patients (6 affected knees) at the final evaluation. However, in these patients, the pain was less severe than it had been preoperatively, and revision surgery for PF pain was needed or performed. The postoperative radiological evaluation was favorable on the whole. The localization of sclerotic changes in the patella on X-ray were in 32 cases around tip of the patella, on the other no remarkable change were in 29 cases. Conclusion. The clinical and radiological evaluations of the patella non−resurfacing mobile bearing total knee arthroplasty was favorable overall. Treatment of the patella in total knee arthroplasty remains controversial. We suggest that the patella in LCS−TKAs does not always need to be resurfaced

Patella resurfacing is becoming more routine in total knee replacements with recent reports indicating improved long term outcomes. Despite this, patella osteotomy relies heavily on how the cutting jig is applied rather than on fixed anatomical landmarks. Recognised complications of asymmetric patella resection are patella fractures, patella maltracking, bony impingement and pain. Accurate instruments have been developed for other aspects of total knee replacements. However cutting guides for the patella tend to be cumbersome with poor reproducibility. Patella tilt is defined as the angle subtended by a line joining the medial and lateral edges of the patella and the horizontal. Keeping this angle to a minimum results in congruent alignment of the patella button within the trochlear groove. Current patella cutting jigs do not take this angle into consideration as they require full eversion of the patella laterally, not only making accurate placement of the jig difficult but also putting excessive strain on the surrounding soft tissue. This study describes a new cutting technique for the patella osteotomy which is referenced off the distal femoral condyles ensuring a more accurate and reproducible cut without having to evert the patella. With the femoral component trial in situ and the patella in its normal anatomical lie, the knee is flexed to 30°. The patella cutting jig is then applied in the usual manner making sure that adequate thickness of patella remains but it is placed parallel to a line joining the two condyles of the femoral component. By cutting the patella in this position parallel to the distal femoral condyles, patella tilt is minimised and the patella button will be aligned evenly within the trochlear groove. Currently all patients requiring patella resurfacing at our institution are undergoing this technique and the short term results have been very promising. This study presents a novel patella cutting technique that utilises a fixed landmark to ensure a more accurate and reproducible osteotomy. We are planning a large scale trial comparing pre- and post-operative knee scores and radiological assessment of patients having this new technique compared to standard cutting techniques. This will allow us to report on the longer term effects and pave the way for better patella resurfacing instrumentation

Purpose Of Study. The in vivo evaluation of patellofemoral contact pressures in a posterior stabilized compared to posterior cruciate sacrificing total knee arthroplasty (TKA). Methods. A prospective descriptive non randomized study was performed on 8 patients. A standard approach to a TKA was performed using a balanced gap technique, while the patella was prepared for a resurfacing. The trial components for the posterior stabilized (PS) TKA where inserted including the gas sterilized pressure transducer (a patella button). Soft tissue was approximated and the knee was taken through full range of movement. Patellofemoral pressure was measured and captured continuously through the full range of movement. The posterior cruciate sacrificing (CS) components were inserted into the same patient and the procedure repeated. In addition, anterior translation of the tibia relative to the femur was measured at 90 degrees. The transducer was removed and final components, including a patella resurfacing were inserted. Results. Significantly lower patella femoral pressures were found for PS TKA compared to CS TKA in full flexion [129.0 ± 21.7 N vs. 109.9 ± 32.1 (p = 0.038173)]. The change in patellofemoral pressure between flexion and extension was significantly lower in PS TKA compared to CS TKA [109.0 ± 21.6 N vs. 90.5 ± 32.0 (p = 0.0037690)]. In addition mean anterior translation at 90° flexion in the CS TKA (6.4 ± 3.2 mm) was significantly less than in PS TKA (17.0 ± 2.6) (p = 0.000072). Conclusion. Significantly lower patellofemoral pressures were found in full flexion with PS TKA compared to CS TKA. The change in patellofemoral pressure in a PS TKA compared to CS TKA was also significantly lower. This study provides possible clinical data when considering patella resurfacing. NO DISCLOSURES

Introduction. Wound condition after primary total knee arthroplasty (TKA) is important for prevention of periprosthetic infection. Any delay in wound healing will cause deep infection, which leads to the arthroplasty failure. Prevention of soft tissue problems is thus essential to achieve excellent clinical results. However, it is unknown as to the important surgical factors affecting the wound healing using detailed wound score after primary TKA so far. It was hypothesized that operative technique would affect wound healing in primary TKA. The purpose of the present study was to investigate and to clarify the important surgical factors affecting wound score after primary TKA. Methods. A total of 139 knees in 128 patients (mean 73 years) were enrolled. All primary TKAs were done by single surgeon. All patients underwent unilateral or bilateral TKA using Balanced Knee System®, posterior stabilized (PS) design (Ortho Development, Draper, UT) or Legion®, PS design (Smith and Nephew, Memphis, TN) under general and/or epidural anesthesia. Patients with immunosuppressive therapy, hypokalemia, poor nutrition (albumin < 3.4 g/dL), diverticulosis, infection elsewhere, uncontrolled diabetes mellitus (HbA1C>7.0%), obesity (Body Mass Index > 35 kg/m2), smoking, renal failure, hypothyroidism, alcohol abuse, rheumatoid arthritis, posttraumatic arthritis, and previous knee surgery were excluded. Hollander Wound Evaluation Score (HWES) was assessed on postoperative day 14. We evaluated age, sex, body mass index, HbA1C (%), preoperative femorotibial angle (FTA) on plain radiograph. In addition, intraoperative patella eversion, intraoperative anterior translation of the tibia, patella resurfacing, surgical time, tourniquet time, unidirectional barbed suture and length of skin incision were also evaluated as surgical factors. Multiple regression analysis was done using stepwise method to identify the surgical factors affecting HWES. Results. Detailed demographic data was presented in Table 1. The average HWES was 5.0 ± 0.8 point. As to the distribution of the HWES, data was shown in Figure 1. Namely, HWES was 3 point in 5 cases, 4 in 29 cases, 5 in 63 cases, and 6 in 42 cases. As any adverse events were not found in each TKA, there were no cases requiring debridement and re-closure of the wound after primary TKA. According to stepwise forward regression test, intraoperative patella eversion and anterior translation of the tibia were entered in this model, while age, Sex, BMI, HbA1C, FTA, surgical time, tourniquet time, patella resurfacing, unidirectional barbed suture and length of skin incision were not entered in the model. The multiple regression analysis in the current study would show the appropriate results, as Durbin-Watson ratio was 1.762. Standardized partial regression coefficient was as follows; 0.57 in anterior translation of the tibia, 0.38 in patella eversion (Table 2). Discussion. The results of the present study would support out hypothesis that operative technique would affect wound healing in primary TKA. Specifically, intraoperative patella eversion and anterior translation of the tibia should be avoided for quality cosmesis of the wound healing in primary TKA. To view tables/figures, please contact authors directly

Introduction. Persistent anterior knee pain, subluxation or dislocation of the patella as well as early aseptic loosening and increased polyethylene wear of the patella implant are common clinical problems after total knee arthroplasty (TKA) which are associated with the patellofemoral joint. In addition to patellar resurfacing, the design of the patellofemoral joint surfaces is attributed a large influence. While for patients without patella resurfacing, the native patella is sliding on the standardized femoral component and therefore the possibility of a reduced surface matching is high, patella resurfacing has been shown to decrease the joint contact area and yield to increased patellofemoral pressure. With regard to a further design optimization, the current study examined patellar biomechanics after TKA without and with resurfacing, comparing 5 differently designed patellofemoral joint surfaces of the femoral implant. Methods. The femoral implant of the Genesis II prosthesis (Smith & Nephew) was scanned and an adaptable CAD-model was built using CATIA. Five different designs of the patellofemoral groove were created:. original. completely flat. laterally elevated (+2mm lateral, −1mm medial). medially elevated (+2mm medial, −1mm lateral). laterally & medially elevated (+3mm lateral+medial). The tibiofemoral joint as well as patellofemoral groove path and radius remained unchanged. Rapid Prototyping was used to produce prototypes made of polyamide. A dynamic muscle loaded knee squat was simulated on 10 fresh frozen knee specimens with an upright knee simulator. The patellofemoral pressure distribution was measured using a flexible, resistive force sensor (TEKSCAN) while tibiofemoral and patellofemoral kinematics were recorded with an ultrasonic motion tracking system (ZEBRIS). In addition, patellar stability was measured in different flexion angles on another 10 specimens using a robot (KUKA). Measurements were taken on the native knee as well as after TKA and after additional patellar resurfacing with alternating femoral implant. Results. Considering patellofemoral kinematics, the largest influence was found for the flat design where increased lateral tilt (up to 6°) and medial shift (up to 5mm) were measured after TKA compared to the native knee. Similar results were achieved for patellar stability, where increased lateral displacement (up to +6mm) was measured for the flat design. The other designs only had a small effect on patellar kinematics and patellar lateral stability. Regarding maximal peak pressure, on average, only a small influence of the designs was found. However, for the individual knee specimens, the pressure distribution and peak pressures varied clearly among the different designs. After additional patellar resurfacing, patellofemoral peak pressures significantly increased (almost doubled), but for the different designs, similar results as before were achieved regarding patellar kinematics, stability and pressures. Conclusions. Increased mediolateral motion was found for the flat design compared to the others and the native knee concluding that a moderate groove is necessary but also sufficient to guarantee stable motion. Especially for maximal patellofemoral peak pressures, large individual differences between the designs were measured while the average influence was small. Therefore, an individual choice between some standard implants might be an interesting option, if appropriate criteria can be found

The LCS RPS knee system is based on the successful LCS mobile bearing prosthesis, and has been introduced with the intention of improving post-operative knee flexion. The aim of this study is to report a high incidence of significant patellofemoral crepitus when this prosthesis is used without patella resurfacing. A successful arthroscopic technique to treat this complication will be described. We present a retrospective review of a single surgeon series of LCS RPS knee arthroplasty. All procedures were performed using a standard technique with cemented components. The patella was not resurfaced in any of the presented cases. The knee society score, patellofemoral score (Baldini et al, 2006), BMI, range of motion, and post-operative radiographs were obtained for all patients. In addition the presence of patellofemoral crepitus was assessed and rated as either none, mild (for limited ROM), moderate (throughout entire ROM), or severe(catching/clunk). An arthroscopic technique to treat this complication was developed. A total of 56 patients were reviewed at a mean follow-up of 16 months (range 9–22). The mean age at time of operation was 70 (range 50–87), and mean BMI was 29 (range 18–42). A lateral release was performed in 7 cases (12%). Mean knee society score was 77 (range 35–92), patellofemoral score 73 (range 25–100), and ROM 115 degrees (range 85–135). Significantly, patellofemoral crepitus was severe in 12 (21%) patients, moderate in 21 (37%), mild in 15 (26%), and absent in 9 (16%). In 4 patients arthroscopic resection of the proximal pole of the patella has resulted in complete resolution of severe crepitus with increases in patellofemoral (mean 25) and knee society (mean 7) scores, and, ROM (mean 15 degrees). One of these patients at 6 month follow-up has reported return of moderate crepitus. Similar resolution of crepitus has been seen in 3 cases which were revised to resurface the patella. As part of this ongoing study a non-randomised comparison group who received patellar resurfacing at the primary procedure has produced no cases of moderate or severe crepitus. In conclusion patella resurfacing is required when using the LCS RPS prosthesis to prevent an unacceptably high rate of moderate to severe patellofemoral crepitus. Both arthroscopic patelloplasty and revision to resurface the patella have resulted in resolution of this problem. Potential biomechanical causes for this problem will be presented