Rate Of Anterior Knee Pain Research Articles

Clinical and Computational Evaluation of an Anatomic Patellar Component

BackgroundAnatomic patellar components for total knee arthroplasty (TKA) have demonstrated favorable in vivo kinematics. A novel failure mechanism in TKA patients with an anatomic patellar component was observed prompting an investigation to identify patient- and implant-related factors associated with suboptimal performance. MethodsA retrospective evaluation was performed comparing 100 TKA patients with an anatomic patellar component to 100 gender-, age-, and body mass index–matched patients with a medialized dome component. All surgeries were performed with the same posterior-stabilized TKA system with minimum of 1-year follow-up. Several radiographic parameters were assessed. A separate computational evaluation was performed using finite-element analysis, comparing bone strain energy density through the patella bone remnant. ResultsPatients with an anatomic patellar component had significantly higher rates of anterior knee pain (18 versus 2%, P < .001), chronic effusions (18 versus 2%, P < .001), and superior patellar pole fragmentation (36 versus 13%, P < .001) compared to those with a dome component. Radiographically, the anatomic group demonstrated more lateral patellar subluxation (2.3 versus 1.1 mm, P < .001) and lateral tilt (5.4 versus 4.0 mm, P = .013). Furthermore, there were more revisions in the anatomic group (7 versus 3, P = .331). On computational evaluation, all simulations demonstrated increased bone strain energy density at the superior patellar pole with the anatomic patella. Resection thickness <13 mm resulted in over 2-fold higher strain energy density, and negative resection angle of 7° resulted in 6-fold higher superior pole strain energy. ConclusionsPatients with an anatomic patellar component showed higher rates of anterior knee pain, chronic effusion, and superior pole fragmentation compared to patients with a dome patella, with higher superior patellar pole strain energy confirmed on computational evaluation. Avoiding higher resection angles and excessive patellar resection may improve the performance and survivorship of the anatomic patella.

Bone-patellar tendon-bone versus two- and four-strand hamstring tendon autografts for ACL reconstruction in young adults: a Bayesian network meta-analysis

Bone-patellar tendon-bone (BPTB), two- and four-strand hamstring tendon (4SHT and 2SHT, respectively) are the most common autografts used for anterior cruciate ligament (ACL) reconstruction. The present study compared BPTB, 2SHT, and 4SHT for ACL reconstruction in terms of joint laxity, patient reported outcome measures (PROMs), rate of failure and anterior knee pain (AKP). The time to return to sport and the peak torque between the autografts were also compared. Finally, prognostic factors leading to worse outcomes were also investigated. It was hypothesized that all grafts yield similar proprieties in terms of joint laxity, patient reported outcome measures (PROMs) and rate of failure, but that the BPTB autograft causes a greater rate of anterior knee pain (AKP). The literature search was conducted. All clinical trials comparing BTPB and/or 2SHT, and/or 4SHT were accessed. Grafts other than BTPB and/or 4SHT and/or 2SHT were not considered. Articles reporting outcomes of allografts or synthetic grafts were not eligible, nor were those concerning revision settings. Articles reporting ACL reconstruction in patients with multi-ligament damage were also not eligible. Data from 95,575 procedures were retrieved. The median length of follow-up was 36 months. The median age of the patients was 27.5 years. With regard to joint laxity, similarity was found in terms of Lachman and Pivot shift tests between all three autografts. The BPTB demonstrated the greatest stability in terms of instrumental laxity. BPTB demonstrated the greatest PROMs. BPTB demonstrated the greatest rate of AKP, while AKP in 2SHT and 4SHT was similar. Concerning failure, statistically significant inconsistency was found (P = 0.008). The 4SHT demonstrated the quickest return to sport, followed by BPTB, and 2SHT. There was evidence of a negative association between the time span between injury to surgery, Lysholm score (P = 0.04), and Tegner scale (P = 0.04). Furthermore, there was evidence of a weak positive association between the time span between injury to surgery and return to sport (P = 0.01). BPTB may result in lower joint laxity, greater PROMs, and greater peak flexion torque compared to 2SHT and 4SHT autografts. On the other hand, BPTB reported the lowest peak extension torque and the greatest rate of AKP. Finally, a longer time span between injury and surgery negatively influences outcome.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-analysis and Trial Sequential Analysis of 50 Randomized Controlled Trials.

During total knee arthroplasty, femur and tibia parts are regularly replaced, while resurfacing the patellar or not is an ongoing discussion. To compare revision rate, anterior knee pain rate, patient-reported outcome measures, complication, radiographic, and clinical outcomes after patellar resurfacing versus non-resurfacing in total knee arthroplasty. PubMed, Medline, EMBASE, CENTRAL, and CINAHL databases were searched on 25 April 2021 to enroll randomized controlled trials that compared patellar resurfacing versus non-resurfacing. We used the grading of recommendations assessment, development and evaluation (GRADE) framework to assess the certainty of evidence. Our primary outcome was revision rate and secondary outcomes was anterior knee pain rate. Outcomes were pooled using the random-effect model and presented as risk ratio (RR), or mean difference (MD), with 95% confidence interval (CI). Fifty studies (5586 knees) were included. Significant reductions in patellar revision rate (RR 0.41, 95% CI [0.19, 0.88]; P=0.02; I2 =24.20%) and non-patellar revision rate (RR 0.64, 95% CI [0.55, 0.75]; P < 0.001; I2 =0%) were seen after patellar resurfacing. Patellar resurfacing significantly reduced the anterior knee pain rate than nonresurfacing (RR 0.72, 95% CI [0.57, 0.91]; P=0.006; I2 =69.5%). Significant differences in patient-reported outcome measures were found. However, these differences were inconsistent and lacked clinical importance. Patellar resurfacing resulted in a significant lower rate of patellar clunk (RR 0.58, 95% CI [0.38, 0.88]; P=0.01; I2 =0%), a higher patellar score (MD 1.24, 95% CI [0.67, 0.81]; P < 0.001; I2 =73.8%), but prolonged surgical time (MD 8.59, 95% CI [5.27, 11.91]; P < 0.001; I2 =88.8%). The clear relationship is that patellar resurfacing reduces revisions, anterior knee pain, and patellar clunk. It will be interesting to compare the initial cost with the revision cost when required and cost-utility analysis with long-term results in future studies.

553 Does Patella Implant Design Affect Outcomes? Patella Resurfacing in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

Abstract Aim To investigate whether implant design affect (1)incidence of anterior knee pain, (2)patient reported outcomes and (3)reintervention rates in a resurfaced vs non-resurfaced Total Knee Arthroplasty (TKA). Method MEDline, pubmed and google scholar studies were evaluated using SIGN assessment tool and data analysis was conducted using Review Manager 5.2 on only randomised controlled trials. Search terms: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, patellar retaining. Results 33 randomised controlled studies were identified. A total of 11 used the modern “patella-friendly” implants and 22 used the older “patella non-friendly” implants. There was no significant difference in anterior knee pain rates for either surgical option. When using patella-friendly implant, patella resurfacing results in a statistically higher clinical (P 0.007, MD -0.77) and functional (P &amp;lt; 0.0001, MD -1.87) KSS than the non-resurfaced counterparts, but scores were not clinically significant. When the patella was not resurfaced, there was a significant increased risk of reoperation with “non-patella friendly” implant (p=0.04, OR 1.42, CI 1.01, 2.00), whilst there was no significant difference between reoperation rates for the “patella friendly” implants (OR 1.17, CI 0.59,2.30). Conclusions Patella implant design has been shown to significantly improve KSS scores but with no clinical significance. Risk of further procedures was significantly higher in non-resurfaced patella TKAs with “non-friendly” implants, likely due to increased rates of anterior knee pain in these older generation implants leading to secondary resurfacing. However, when utilising “patella-friendly” implants, resurfacing does not lower reintervention rates. This meta-analysis finds no clinical indication to resurface the patellar whilst performing a TKA.

Effect of femoral component rotational alignment in total knee arthroplasty by using 3D-printed patient-specific instruments: a prospective randomized control study

Objective: To compare the difference between two total knee arthroplasty (TKA) techniques, patient-specific instrumentation (PSI) and conventional instrumentation (CI), regarding the rotational alignment of femoral components. Methods: A prospective, randomized controlled trial in 80 patients with severe knee osteoarthritis who underwent primary unilateral TKA from October 2018 to December 2019 in Peking University Third Hospital was carried out. There were 63 females and 17 males, with an average age of 69 years. The patients were assigned to either PSI-TKA group (n=40) or CI-TKA group (n=40) with bluster random method (block size 4). The femoral component rotation on the transepicondylar axis, the outlier rate of rotational alignment, the rate of anterior knee pain, and the clinical outcomes including HSS and WOMAC score at 1-year follow-up were documented and analyzed. Results: Although no significant difference in femoral component rotational alignment was found between the two groups (CI-TKA: 0.7°, PSI-TKA: 0.6°, P=0.279), the PSI-TKA group achieved less coefficient of variation of rotational alignment (1.50 vs 2.14) and the distributions of the outliers (19.4% vs 7.9%, P=0.185). Six patients (8.1%) experienced anterior knee pain at 1-year follow-up. No significant difference regarding the incidence of anterior knee pain, the HSS, and WOMAC score was found between the two groups one year after the operation (all P>0.05). Conclusions: The satisfied postoperative rotational alignment of femoral components can be attained with the application of PSI in comparison with conventional instrumentation. In addition, PSI offers a potential benefit in the reduction of alignment outliers.

Midterm functional recovery of Total knee arthroplasty patients compared between the ATTUNE knee system and the press fit condylar (PFC) SIGMA knee system

BackgroundThe ATTUNE Knee System is a new prosthetic design that has theoretical advantages over the Press Fit Condylar (PFC) Sigma Knee System specific to improved knee kinematics and patellofemoral joint tracking. This study aimed to evaluate functional outcomes compared between the ATTUNE and PFC Sigma designs at a minimum follow-up of 5 years.MethodsWe retrospectively reviewed data from total knee arthroplasty (TKA) patients who received either the ATTUNE or PFC Sigma system during November 2013 to February 2015 at Siriraj Hospital (Bangkok, Thailand). Functional outcomes were evaluated using Timed Up and Go (TUG) test, 2-min walk test (2MWT), modified knee score, numerical rating scale-pain, range of motion (ROM), and rate of anterior knee pain and crepitation at preoperation, 3-months, 1-year, and 5-years postoperatively.ResultsOf 113 patients, 59 and 54 received the PFC Sigma and ATTUNE systems, respectively. At a minimum of 5-years follow-up, all functional outcomes improved significantly from the preoperative period although TUG test and 2MWT declined significantly from 1- to 5-years postoperatively only in the PFC Sigma group. The mean ROM at 5-years postoperatively was significantly higher in ATTUNE than in PFC Sigma; however, the difference was small (116° vs. 110°, respectively; p = 0.041). There were no significant differences in any of the other outcome measurements, including anterior knee pain, clunking, and crepitation, between groups at any study time point.Conclusions​Our results revealed no major differences in functional outcomes between the PFC Sigma and ATTUNE TKA designs at an intermediate-term follow-up of at least 5 years. Longer-term follow-up study is needed to evaluate the benefits of the ATTUNE design relative to polyethylene wear and the rate of aseptic loosening.

Pain and patellofemoral functionality in total knee arthroplasty: a comparative cohort study of two prosthesis designs

Background: Total knee arthroplasty designs have changed from the original design, with the goal of becoming as close to normal knee biomechanics and anatomy as possible. Since 2009, Optetrak® Logic incorporated modifications to the previous product Optetrak® PS (Exactech, Gainsville, FL), with a change of the anterior surface of the tibial post of the polyethylene insert and the surface that articulates with the femoral component box. Also, the sagittal geometry of the femoral trochlea was changed, which decreased rates of anterior knee pain and “patellar clunk.” The purpose of this study was to determine if there are differences in terms of pain and patellofemoral functionality between Optetrak PS and Optetrak Logic. Methods: A prospective follow-up was performed comparing the results of the Kujala pain and patellofemoral functionality scale. Clinical and functional follow-up was performed in 132 knees (66 from the Optetrak Logic group and 66 from the Optetrak PS group) that underwent total knee arthroplasty from January 2015 to August 2019. Results: Global results of the functional tests were: Oxford postoperative 50; Knee Society Score postoperative 85; Kujala postoperative 76. In comparing the two groups the Kujala score for Optetrak PS was 71 and the Kujala score for Optetrak Logic was 81. Conclusions: Patellofemoral knee pain and functionality before and after total knee arthroplasty must be analyzed with functional scales. The new prosthetic designs are gentler to the patellofemoral joint, and this has been verified by objective analysis with functional scales such as the Kujala scale. Level of Evidence: Level III.

Design Modifications of the Posterior-Stabilized Knee System May Reduce Anterior Knee Pain and Complications Following Total Knee Replacement.

In total knee arthroplasty (TKA), advances in posterior-stabilized (PS) knee implant designs address patellofemoral mechanics and cam-post engagement in an effort to reduce patellofemoral pain and improve knee kinematics. Such modifications may include improved femoral rollback, improved femoral dislocation resistance, minimized wear, and improved longevity. In this study, we compared a newer PS knee design that incorporates a left and right specific femoral component and smoother trochlear groove to improve patellofemoral mechanics with an older PS design in order to assess patellofemoral pain, manipulation rates, and revision rates. Using an institutional database, we retrospectively identified TKAs performed by the same surgeon using the Logic® PS knee system and theolder Optetrak PS knee system (Exactech Inc., Gainesville, FL, USA), with a minimum 2-year follow-up. Clinical outcomes for each cohort were measured using the Knee Society Clinical Rating System, University of California Los Angeles Activity Scale, pain visual analog scale(VAS), Veterans Rand 12-Item Health Survey, and Western Ontario and McMaster Universities Osteoarthritis Index. In addition, rates of anterior knee pain, manipulation, and revision were compared between the two knee systems, and a Kaplan-Meier survivorship curve defining failure as need for revision was calculated to allow comparison between the cohorts. From 2000 to 2018, there were 1482 TKAs performed using the Logic PS (not counting 12 patients who had died) and 445 in the Optetrak PS group (not counting 20 patients who had died). In the Logic PS and Optetrak PS groups, respectively, the average age at operation was 66.7years and 68.6years and the average body mass index was 30.8 and 31.2. Pain VAS scores were significantly lower in the Logic PS group than in the Optetrak group (1.72 vs. 2.75out of 10, respectively). There was also a significant difference inthe percentages of patients reporting anterior knee pain in the Logic group, as compared with the Optetrak group (5.6% vs. 11.8%, respectively). In addition, manipulation rates differed significantly between the Logic and Optetrak groups (0.34% vs. 10.70%, respectively). The revision rates were 1.15% for the Logic group and 2.0% for the Optetrak group. However, there was a significant difference in rates of revision performed because of osteolysis, favoring the Logic group (0.07% vs. 0.6%). The Kaplan-Meier survivorship curve shows a significant difference in time until revision between the Logic and Optetrak groups. Design modifications to improve patellofemoral mechanics demonstrated significant improvements in overall pain and patellofemoral pain and reduced manipulation rates post-operatively.

Better outcomes with patellar resurfacing during primary total knee arthroplasty: a meta-analysis study.

Total knee arthroplasty (TKA) is a feasible and cost-effective procedure. However, resurfacing of the patella sparks a heated debate. Anterior knee pain after TKA was supposed to be correlated to the patellofemoral joint, and the resurface of the patella was believed to be effective to avoid this complication. A meta-analysis was performed to update current evidence concerning the outcomes of patellar resurfacing versus retaining for total knee arthroplasty. The first outcomes of interest were to compare the rate of anterior knee pain and revision surgeries. This study was conducted according to the preferred reporting items for systematic reviews and meta-analyses(PRISMA). A comprehensive review of the literature was conducted accessing the main databases: Embase, Google Scholar, PubMed, Scopus. All the prospective clinical trials comparing the outcomes between patellar resurfacing versus retaining were included in this study. Only articles classified as level of evidence I to II were considered for inclusion. Only studies reporting a minimum 24months follow-up were included. The following data were extracted: demographic baseline, anterior knee pain, reoperations, clinical scores (HSS, KSS and related subscales) and range of motion (ROM). Studies solely reporting quantitative data under the outcomes of interest were included. In favor of the resurfacing group, we observed a statistically significant reduced rate of anterior knee pain (odd ratio 1.73) and reoperation (odd ratio 3.24). In the resurfacing group, a prevalence of anterior knee pain of 11.15% was detected, whereas in the retaining group it amounted to 17.39%. Furthermore, a greater KSS pain (+ 0.97%), KSS clinical (+ 0.23%), KSS functional (+ 2.44%), KSS overall (+ 2.47%) and HSS (+ 5.64%) were reported. In the retaining group, we found a better range of motion (+ 3.09°). Based on the main findings of this meta-analysis, patellar resurfaced TKA was demonstrated to have performed superior overall. Patellar resurfacing detected a lower rate of postoperative anterior knee pain and reoperation. Moreover, the resurfacing group showed greater value of the HSS, KSS and related subscales. In favor of the retaining group, a slightly better ROM was evidenced. Level II, meta-analysis of prospective clinical trials.

Patients undergoing total knee arthroplasty using a contemporary patella-friendly implant are unaware of any differences due to patellar resurfacing.

Anterior knee pain after total knee arthroplasty (TKA) is often unexplained, spurring ongoing debates on the need for patellar resurfacing. It was hypothesized that a contemporary patella-friendly implant would restore patellofemoral kinematics more physiologically than outdated implants and that there would be no perceived or clinically demonstrable differences due to resurfacing of patella (RP). This prospective bilateral randomized study was undertaken in 49 patients scheduled for the same-day bilateral TKAs. One knee was subjected at random to RP while withholding RP on the opposing side (non-RP). A recently approved single-radius femoral prosthesis featuring a deep, elongate trochlear groove with lateral tilt and a high lateral flange was implanted bilaterally in all patients. Mean follow-up duration was 5years. Group comparisons were based on patient-reported outcomes [anterior knee pain, Forgotten Joint Score (FJS), and side preference], physician-rated results [Feller patellofemoral (PF) score], radiographic patellar position, patella-related complications, and need for reoperation. There were no differences in midterm rates of anterior knee pain (RP 8%; non-RP 4%; n.s.), FJS (all n.s.), or side preference (RP 47%; non-RP 45%; n.s.), nor did the groups differ by Feller PF score (all n.s.) or radiographic patellar position (all n.s.). No secondary resurfacings of non-RP or RP revisions were required. Patients were incapable of distinguishing whether RP was done, casting doubt on its benefits. Surgeons may thus forego RP during TKA when using contemporary patella-friendly TKA implants. Therapeutic study, Level I.

Quadriceps strength and anterior knee pain following tibia intramedullary nailing: Any clinical relationship?

Anterior knee pain can be chronic sequelae of intramedullary nailing of the tibia. Several causes have been identified; no single reason can fully explain the occurrence. We, therefore, set out to find the rate of anterior knee pain in our practice and if any relationship exists between the anterior knee pain and extensor muscle strength. A total of 72 knees in 36 patients with no prior history of knee pain, but had unilateral tibiofibular fracture, who had internal fixation with interlocking intramedullary nailing done and were followed up for at least 1 year were recruited into the study. The tension generated on extension of the knee against a resistance using tensiometer was measured in Newton. The ranges of motion of the knees were documented, as well as Lysholm score which measures activities and document the presence and limitation caused by anterior knee pain. A total of 36 patients with 72 knees were studied. Anterior knee pain occurred in 7 (19.4%) patients in this study. There was no statistically significant relationship between the force of tension (N) generated in the extensor in patients with anterior knee pain compared with those without knee pain (158.43 ± 49.35, 189.54 ± 74.63, P = 0.304). There was, however, a significant statistical relationship between the mean Lysholm score of the operated and unoperated knee (P = 0.042). Anterior knee pain rate was 19.4% in our series and no statistical association exists between the extensor strength and occurrence of anterior knee pain.

Influence of the Infrapatellar Fat Pad Resection during Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

BackgroundTo enhance surgical exposure, resection of the infrapatellar fat pad (IPFP) is usually a routine procedure in total knee arthroplasty (TKA). However, there is conflicting evidence regarding whether IPFP resection during TKA impairs clinical outcome. We performed a systematic review and meta-analysis to clarify the influence of IPFP resection on primary TKA.MethodsEmbase, PubMed, and the Cochrane Library were systematically searched up to August 2016 to identify relevant studies. All clinical studies comparing IPFP resection (IPFP-R) and IPFP preservation (IPFP-P) in patients undergoing primary TKA were obtained. The meta-analysis was performed with Revman 5.3 and STATA 12.0 software. The weighted mean was estimated by using random effects (RE) models with 95% CIs, heterogeneity was assessed using the H statistic and the inconsistency index (I2).ResultsSeven studies involving 2,734 patients (3,258 knees) were included. IPFP resection trended to increase the incidence of postoperative anterior knee pain within 2 months postoperatively, compared with patients in whom the IPFP was preserved (odds ratio [OR]s 2.12[0.95, 4.73], p = 0.07). An increased incidence of anterior knee pain was observed in the IPFP resection group > 12 months postoperatively, but the difference was not significant (OR, 3.69 [0.81, 16.82], p = 0.07). In addition, a trend towards more shortening of the patellar tendon was also observed in the IPFP-R group. No significant results were found regarding postoperative knee function.ConclusionThese results suggest that preserving the IPFP may be superior to IPFP resection in patients undergoing primary TKA, due to the relatively lower rate of anterior knee pain after short-term follow-up.

Long term follow up of clinical outcome between patellar resurfacing and nonresurfacing in total knee arthroplasty: Chinese experience

Background The long term outcome of patellar resurfacing in Chinese has not been well described. This study evaluated more than 10-year clinical outcomes and survivorship of patellar resurfacing or nonresurfacing in total knee arthroplasty. Methods From January 1993 to December 2002, 265 patients accepted total knee arthroplasty in Department of Orthopaedic Surgery, Peking Union Medical College Hospital. Among them, 226 patients (246 knees) were successfully followed up, with 176 knees for patellar resurfacing and 70 knees for nonresurfacing. The survivorship of total knee arthroplasty between two groups and the hospital for special surgery knee score (HSS), patellar score, patellar related complication and radiological results were studied at the latest follow-up. Results The HSS knee score increased from 55.9±12.2 preoperatively to 92.0±10.9 postoperatively for patellar resurfacing group and from 56.6±9.9 to 94.2±11.4 for nonresurfacing group after average 11.4-year follow-up. Patellar score increased from 13.93±2.42 preoperatively to 28.33±2.20 for resurfacing group and from 13.55±2.73 to 27.8±2.37 for nonresurfacing group. There was no statistically significant difference for both HSS score, patellar score between the two groups with higher rate of anterior knee pain for nonresurfacing group. Patellar nonresurfacing had higher lateral subluxation than resurfacing group according to radiological evaluation. Patients with rheumatoid arthritis had 5.5 fold patellar related complication than patients with osteoarthritis. The 10-year survival rate was not statistically significant different between the two groups (P=0.12). Conclusions There was no significant difference of long-term clinical outcome and survivorship between patellar resurfacing and nonresurfacing. Patellar nonresurfacing can be advisable during primary total knee arthroplasty especially in Chinese patients with osteoarthritis. Selective patellar resurfacing for patients with rheumatoid arthritis can achieve lower patella related complication.

The importance of the third knee compartment on outcome following total knee arthroplasty

The third compartment, the patellofemoral joint, appears to have been neglected somehow when discussing optimal knee kinematics in total knee arthroplasty (TKA). How much impact will good function of the patellofemoral joint have on the clinical outcome after TKA? There is an extensive amount of discussion on whether or not the patella should be resurfaced in TKA. Some surgeons resurface the patella routinely, some never and some selectively, depending on the shape of the patella. A meta-analysis of all randomized studies until 2009 showed no difference between resurfacing or not of the patella in terms of postsurgical rate of anterior knee pain, knee pain score and quality of life [10]. The overall incidence of anterior knee pain after TKA without patella resurfacing ranged between 12 and 87 % [14, 20]. Anterior knee pain has been shown to impair patient’s quality of life. The literature review about anterior knee pain after TKA published in the current issue shows that there is more than one reason for patellofemoral pain [21]. Variables, which may directly influence patellofemoral loading, appear to show an impact on clinical and functional outcome. In conclusion, correct kinematic seems to be important. Biomechanical studies have proven that patella kinematic during knee flexion is very complex because of the combination of rotation, flexion and mediolateral shift. Considering the amount of patellofemoral forces of more than 3 times body weight, minor changes of patella tracking may cause significant impact on the loading condition [16]. In vivo fluoroscopy data were used, and patellofemoral force was calculated using a 3D mathematical model. Interestingly, patellofemoral contact did not differ between normal, cruciate retaining and posterior stabilized total knee arthroplasty. The data were in contrast to the biomechanical findings reported by others. It has been shown that patellofemoral pressure increases up to 1.5–2.5 times after TKA in comparison with the natural knee [13]. Studies have also reported about the impact of the component design on femoropatella pressure [4]. Of course, it depends on the components shape of both the patella and the trochlea groove. Six different patella designs are most commonly used in TKA: the dome, offset dome, modified dome, anatomic mobile bearing, anatomical and cylindrical type of patella [15]. The design of the patella component significantly influences patella tracking also. The dome-shaped patella shows a more internal and external rotation for instance, compared with a more anatomical component [7]. Anatomical studies have shown that the morphology of the femur, tibia and patella varies tremendously. How much of the anatomy do we restore when performing TKA? Do we require a more patient-specific trochlea design? There seems to be a direct relation between the shape of the trochlea and patella kinematic and pain [9]. The articular cartilage depth, the length of the trochlea groove and the height of the patella significantly influence patella tracking. It is well known that femoral component malrotation will affect the femoropatella joint [5, 11]. Increased internal rotation will cause overstuffing of the lateral facet. R. Becker (&) Department of Orthopaedics and Traumatology, Hochstrasse 26, 14770 Brandenburg/Havel, Germany e-mail: roland_becker@yahoo.de

Patellar resurfacing complications in total knee arthroplasty

The ideal management of the patella during total knee arthroplasty (TKA) is still controversial. Patellar retention is generally associated with an increased rate of anterior knee pain; however, patient satisfaction is similar in cases of replacement or retention. When the patella is replaced, potential severe complications can occur. Aim of this study was to retrospectively review results of a continuous series of patients having been treated with TKA and patella resurfacing. The charts of 1,600 consecutive total knee prostheses were analysed to evaluate the rate of patellar resurfacing. All implants were posterior stabilized; 310 patients having received a patellar replacement were reviewed at follow-up (FU) examination. Complete physical examination as well as administration of the Hospital for Special Surgery (HSS) score was performed. X-rays analysis included weightbearing anteroposterior (AP) and lateral views of the injured knee and bilateral skyline views at 30° flexion. Two hundred and eighty patients were available for clinical and imaging investigation at an average FU of 96 (58-144) months. Mean age at the time of surgery was 70 (62-80) years. Mean HSS score was 85.9 ± 7.6. The overall rate of patellofemoral complications was 7% (19 cases); 13 patients claimed anterior knee pain, five had symptomatic patellar maltracking and one had patellar component loosening. Our data are in accordance with those available in the literature. Recent meta-analyses demonstrated lower risk of re-operation after patellar resurfacing. However, when complications of the resurfaced patella occur, they can be potentially catastrophic events.

The efficacy of patellar decompression for improving anterior knee pain following total knee arthroplasty without patellar resurfacing

Anterior knee pain remains common following total knee arthroplasty (TKA). In this study, we evaluated the efficacy of patellar decompression via drilling for the treatment of anterior knee pain following TKA without patellar resurfacing. A prospective cohort study was performed in 271 consecutive patients who underwent primary total knee replacement with patellar decompression (study group, n=131) or without decompression (control group, n=140). The patients were assessed according to the Knee Society rating, clinical anterior knee pain score, and British Orthopaedic Association patient-satisfaction score in each group. Each assessment was performed without the examiner knowing whether the patella had been decompressed. Radiographic evaluations were also performed according to the Knee Society scoring system for functional activity and our own severity grade system for patellofemoral articular change. There were no adverse events following patellar decompression. The overall prevalence of anterior knee pain was not significantly different between groups (p=0.71). However, patients presenting pain over grade II after the operation in the study group were statistically low (p=0.01). The overall postoperative knee scores were higher in the study group, but there were no significant differences between groups (p=0.0731). Analyses of the radiographs revealed similar postoperative outcomes in both groups of knees. As we observed significantly lower rates of anterior knee pain and no patellar complications following patellar decompression via drilling in TKA without patellar resurfacing, we recommend performing patellar decompression in cases of total knee replacement without patellar resurfacing.

Clinical Results of a Total Knee Prosthesis with Floating Platform at 5.5 Years

Abstract In this study, 117 patients who had received the e.motion FP prosthesis between 2001 and 2003 were followed up for 5.5 years to assess the clinical and radiological outcomes and survival of this mobile platform prosthesis. As this design is intended to improve the mobility of the replaced knee, particular emphasis was placed on the clinical and functional results. The hypothesis was that they would be comparable to the excellent results reported in the literature of state-of-the-art total knee arthroplasty. After 66months, the average Knee Society clinical and functional scores were 93.8 points (KSS-C) and 90.5 (KSS-F) points, respectively. The clinical and radiographical results were excellent, with a low rate of anterior knee pain of 2.3 %.

Patellar tendon autograft versus 4-strand hamstring autograft for endoscopic reconstruction of anterior cruciate ligament:a Meta-analysis

Objective To compare clinical outcomes of patellar tendon and 4-strand hamstring au- tografts in single-bundle endoscopic reconstruction of anterior cruciate ligament （ACL） . Methods The digital databases （PubMed, Embase, Cochrane Central Register of Controlled Trials, CBM）were searched for randomized controlled trials （RCTs） comparing patellar tendon with hamstring autografls for reconstruction of ACL. In addition, the reference lists from related original studies and review articles were hand-searched. The Coehrane Collaboration＇ s tool for assessing risk of bias and Cochrane collaboration＇s RevMan 5.0 software were used for assessing trial methodological quality and data analyses. Results Fourteen RCTs were included. There were 1232 participants who met inclusion criteria in all studies. Meta-analyses showed that no statistically significant differences were found in graft failure rate after single-bundle reconstruction of the ACL at mean follow-ups of 2 to 3 years （ RR = 0.69, 95% CI O. 34 to 1.38, P = 0. 29, of 5 years （ RR = 0. 37, 95% C]0.09 to 1,55, P=0. 18）, of 10 years （P=0.94） or when 3 subgroups combined （RR=0.71, 95% CI O. 39 to 1.31, P =0.28） . The difference in ~〉 5~ extensor deficit was not statistically significant between the 2 groups （ RR = 1.63, 95% CI O. 85 to 3.16, P = 0. 14）. Anterior knee pain and kneeling pain or discomfort showed significantly differences between the 2 groups at a mean follow-up of 2 years （ P 〈 0. 05）, but did not at follow-ups of 5 years and 10 years （ P 〉 0. 05）. Conclusions In single-bundle endoscopic ACL reconstruction, patellar tendon and 4-strand hamstring autografts have similar rates of graft failure and knee motion deficits. The patellar tendon autograft may have higher rates of anterior knee pain and kneeling pain or discomfort at an early stage after operation than the 4-strand hamstring autograft, but there may be no such differences on a long-term basis. Key words: Patella ligament; Anterior erueiate ligament; Meta-analysis; Hamstring

Patellar reshaping versus resurfacing in total knee arthroplasty — Results of a randomized prospective trial at a minimum of 7 years' follow-up

ObjectiveTo compare the results of primary total knee arthroplasty with patellar reshaping or resurfacing. MethodsOne hundred thirty-three patients were randomized into patellar reshaping group and patellar resurfacing group. Patellar reshaping includes resecting the partial lateral facet of the patella and the osteophytes surrounding the patella, trimming the patella to match the trochlea of the femoral component. The minimum follow-up time was 7years. The outcome was measured by anterior knee pain rate, Knee Society clinical score, and radiographs. ResultsEight patients in the reshaping group (12.5%) and 10 patients in the resurfacing group (14.7%) complained of anterior knee pain (P=0.712). Meanwhile, there were no significant differences between the two groups in terms of total Knee Society score, Knee Society pain score, Knee Society function score, as well as anterior knee pain rate. ConclusionsWith the numbers available, there was no significant difference between the groups treated with patellar reshaping or patellar resurfacing with regard to the KSS, anterior knee pain rate and radiographs. We prefer reshaping the patella to resurfacing the patella because the former preserves sufficient patellar bone stock and can easily be converted to patellar replacement if patients complain of recurrent anterior knee pain.

Outcome of total knee arthroplasty combined patelloplasty for end-stage type A hemophilic arthropathy

The aim of this study was to retrospectively evaluate the outcome of total knee arthroplasty for end-stage hemophilic arthropathy, based on effectiveness of operation, the specificity of surgical technique, the complications of TKA operation and the strategy of handling of patella. Nineteen patients (25 knees) with type A hemophilic arthropathy were treated with TKA from June 2003 to February 2010. Average patella thickness was 16.3±0.4mm and all patellas were treated by patelloplasty. The patient followed up data was recorded, which included the information of hospital for special surgery knee score(HSS), range of motion(ROM), post-operative complication, and anterior knee pain. The patients were followed for an average post-operative period of 41months (10 to 78months). The mean preoperative HSS score was 51 (31 to 64). Post-operative HSS score was 91 (75 to 110) when followed-up. ROM was modified to 82 degree (60 to 105), compared with 55 degree (5 to 110) preoperatively. Thirteen patients with flexion contracture were corrected from 19 degree (0 to 45) to 2.7 degree (0 to 10). Four patients complained mild but endurable anterior knee pain. The study concludes that TKA is an effective treatment for end-stage hemophilic arthropathy of knee joint, providing good clinical outcome and improving quality of life. Patella of hemophiliac is relatively thin and osteoporotic. Patelloplasty is useful technique for handling of patella during TKA procedure for hemophiliac, with improved knee function, low and acceptable anterior knee pain rate, low reoperation rate.