Background:. The literature is unclear about the optimal rotation of the femoral component during TKR. Measured resection techniques rely on the use of bony landmarks, while the balanced gap technique relies on soft tissue tensioning to guide the surgeon in rotating the femoral component. All these techniques still result in a wide range of component rotation. We compared the functional flexion axis (FFA) of 20 replaced knees to that of the contralateral normal knee to determine whether a balanced gap technique allowed us to recreate this normal anatomy. Methods:. We reviewed the records of our TKR's from Jan 2008 to Dec 2010 and included all patients who had a normally functioning contralateral knee, tibial cut <3° from perpendicular to the mechanical axis performed by/under supervision of a single surgeon. These patients were contacted for follow up and axial flexed knee x-rays to measure femoral rotation and FFA (angle between clinical transepicondylar line and mechanical axis of tibia). These values were compared between replaced and normal knees using Students T-test. Results:. 20 patients were eligible for the study. Femoral component rotation ranged from 4° internal to 5° external rotation (mean of 0.6° external). Mean difference in functional flexion axis was 3.7°, ranging from 0 to 6° (p<0.05). Conclusion:. The balanced gap technique is effective to restore the functional flexion axis of the replaced knee to that of the normal contralateral side

Introduction

Previous fluoroscopic studies compared total knee arthroplasty (TKA) kinematics to normal knees. It was our hypothesis that comparing TKA directly to its non-replaced controlateral knee may provide more realistic kinematics information. Using fluoroscopic analysis, we aimed to compare knee flexion angles, femoral roll-back, patellar tracking and internal and external rotation of the tibia.

Reconstruction of the anterior cruciate ligament (ACL) allows to restore stability of the knee, in order to facilitate the return to activity (RTA). Although it is understood that the tendon autograft undergoes a ligamentous transformation postoperatively, knowledge about longitudinal microstructural differences in tissue integrity between types of tendon autografts (ie, hamstring vs. patella) remains limited. Diffusion tensor imaging (DTI) has emerged as an objective biomarker to characterize the ligamentization process of the tendon autograft following surgical reconstruction. One major limitation to its use is the need for a pre-injury baseline MRI to compare recovery of the graft, and inform RTA. Here, we explore the relationship for DTI biomarkers (fractional anisotropy, FA) between knees bilaterally, in healthy participants, with the hypothesis that agreement within a patient's knees may support the use of the contralateral knee as a reference to monitor recovery of the tendon autograft, and inform RTA. Fifteen participants with no previous history of knee injuries were enrolled in this study (age, 26.7 +/− 4.4 years; M/F, 7/8). All images were acquired on a 3T Prisma Siemens scanner using a secured flexible 18-channel coil wrapped around the knee. Both knees were scanned. A 3D anatomical Double Echo Steady State (DESS) sequence was acquired on which regions of interest (ROI) were placed consistent with the footprints of the ACL (femur, posteromedial corner on medial aspect of lateral condyle; tibia, anteromedial to intercondylar eminence). Diffusion images were acquired using fat saturation based on optimized parameters in-house. All diffusion images were pre-processed using the FMRIB FSL toolbox. The footprint ROIs of the ACL were then used to reconstruct the ligament in each patient with fiber-based probabilistic tractography (FBPT), providing a semi-automated approach for segmentation. Average FA was computed for each subject, in both knees, and then correlated against one another using a Pearson correlation to assess the degree of similarity between the ACLs. A total of 30 datasets were collected for this study (1/knee/participant; N=15). The group averaged FA (+/− standard deviation) for the FBPT segmented ACLs were found to equal 0.1683 +/− 0.0235 (dominant leg) and 0.1666 +/− 0.0225 (non-dominant leg). When comparing both knees within subjects, reliable agreement was found for the FBPT-derived ACL with a linear correlation coefficient (rho) equal to 0.87 (P < 0 .001). We sought to assess the degree of concordance in FA between the knees of healthy participants with hopes to provide a method for using the contralateral “healthy” knee in the comparison of autograft-dependent longitudinal changes in microstructural integrity, following ACL reconstruction. Our results suggest that good agreement in anisotropy can be achieved between the non-dominant and dominant knees using DTI and the FBPT segmentation method. Contralateral anisotropy of the ACL, assuming no previous injuries, may be used as a quantitative reference biomarker for monitoring the recovery of the tendon autograft following surgical reconstruction, and gather further insight as to potential differences between chosen autografts. Clinically, this may also serve as an index to supplement decision-making with respect to RTA, and reduce rates of re-injuries

With the rising rates, and associated costs, of total knee arthroplasty (TKA), enhanced clarity regarding patient appropriateness for TKA is warranted. Towards addressing this gap, we elucidated in qualitative research that surgeons and osteoarthritis (OA) patients considered TKA need, readiness/willingness, health status, and expectations of TKA most important in determining patient appropriateness for TKA. The current study evaluated the predictive validity of pre-TKA measures of these appropriateness domains for attainment of a good TKA outcome. This prospective cohort study recruited knee OA patients aged 30+ years referred for TKA at two hip/knee surgery centers in Alberta, Canada. Those receiving primary, unilateral TKA completed questionnaires pre-TKA assessing TKA need (WOMAC-pain, ICOAP-pain, NRS-pain, KOOS-physical function, Perceived Arthritis Coping Efficacy, prior OA treatment), TKA readiness/willingness (Patient Acceptable Symptom State (PASS), willingness to undergo TKA), health status (PHQ-8, BMI, MSK and non-MSK comorbidities), TKA expectations (HSS KR Expectations survey items) and contextual factors (e.g., age, gender, employment status). One-year post-TKA, we assessed for a ‘good outcome’ (yes/no), defined as improved knee symptoms (OARSI-OMERACT responder criteria) AND overall satisfaction with TKA results. Multiple logistic regression, stepwise variable selection, and best possible subsets regression was used to identify the model with the smallest number of independent variables and greatest discriminant validity for our outcome. Receiver Operating Characteristic (ROC) curves were generated to compare the discriminative ability of each appropriateness domain based on the ‘area under the ROC curve’ (AUC). Multivariable robust Poisson regression was used to assess the relationship of the variables to achievement of a good outcome. f 1,275 TKA recipients, 1,053 (82.6%) had complete data for analyses (mean age 66.9 years [SD 8.8]; 58.6% female). Mean WOMAC pain and KOOS-PS scores were 11.5/20 (SD 3.5) and 52.8/100 (SD 17.1), respectively. 78.1% (95% CI 75.4–80.5%) achieved a good outcome. Stepwise variable selection identified optimal discrimination was achieved with 13 variables. The three best 13-variable models included measures of TKA need (WOMAC pain, KOOS-PS), readiness/willingness (PASS, TKA willingness), health status (PHQ-8, troublesome hips, contralateral knee, low back), TKA expectations (the importance of improved psychological well-being, ability to go up stairs, kneel, and participate in recreational activities as TKA outcomes), and patient age. Model discrimination was fair for TKA need (AUC 0.68, 95% CI 0.63-0.72), TKA readiness/willingness (AUC 0.61, 95% CI 0.57-0.65), health status (AUC 0.59, 95% CI 0.54-0.63) and TKA expectations (AUC 0.58, 95% CI 0.54-0.62), but the model with all appropriateness variables had good discrimination (AUC 0.72, 95% CI 0.685-0.76). The likelihood of achieving a good outcome was significantly higher for those with greater knee pain, disability, unacceptable knee symptoms, definite willingness to undergo TKA, less depression who considered improved ability to perform recreational activities or climb stairs ‘very important’ TKA outcomes, and lower in those who considered it important that TKA improve psychological wellbeing or ability to kneel. Beyond surgical need (OA symptoms) and health status, assessment of patients’ readiness and willingness to undergo, and their expectations for, TKA, should be incorporated into assessment of patient appropriateness for surgery

INTRODUCTION. Controversy exists regarding the ability of unicompartmental knee arthroplasty (UKA) to restore native knee kinematics, with some studies suggesting native kinematics are restored in most or all patients after UKA. 1–3. , while others indicate UKA fails to restore native knee kinematics. 4,5. Previous analysis of UKA articular contact kinematics focused on the replaced compartment. 2,5. , neglecting to assess the effects of the arthroplasty on the contralateral compartment which may provide insight to future pathology such as accelerated degeneration due to overload. 6. or a change in the location of cartilage contact. 7. The purpose of this study was to assess the ability of medial UKA to restore native knee kinematics, contact patterns, and lateral compartment dynamic joint space. We hypothesized that medial UKA restores knee kinematics, compartmental contact patterns, and lateral compartment dynamic joint space. METHODS. Six patients who received fixed-bearing medial UKA consented to participate in this IRB-approved study. All patients (4 M, 2 F; average age 62 ± 6 years) completed pre-surgical (3 weeks before) and post-surgical (7±2 months) testing. Synchronized biplane radiographs were collected at 100 images per second during three repetitions of a chair rise movement (Figure 1). Motion of the femur, tibia, and implants were tracked using an automated volumetric model-based tracking process that matches subject-specific 3D models of the bones and prostheses to the biplane radiographs with sub-millimeter accuracy. 8. Anatomic coordinate systems were created within the femur and tibia. 9. and used to calculate tibiofemoral kinematics. 10. Additional outcome measures included the center of contact in the medial and lateral compartments, and the lateral compartment dynamic joint space (i.e. the distance between subchondral bone surfaces). 11. The results of the three movement trials were averaged for each knee in each test session. All outcome measures were interpolated at 5° increments of knee extension (Figure 2). The average differences between knees at corresponding flexion angles were analyzed using paired t-tests with significance set at p < 0.05. RESULTS. The UKA knee was in 5.3° more varus than the contralateral knee prior to surgery (p=0.005). After surgery, the UKA knee was in 4.9° more valgus than before surgery (p=0.005). The UKA knee was 4.3° more externally rotated than the contralateral knee post-surgery (p=0.05) (Table 1). No significant differences were observed between knees or pre- to post-surgery in lateral compartment dynamic joint space or the center of contact in the medial and lateral tibia compartments (Table 1). DISCUSSION. These results suggest that medial UKA can restore native knee varus without significantly altering lateral compartment joint space or contact location during the chair rise movement. For any figures or tables, please contact the authors directly

Knee warmth is a common clinical observation following total knee arthroplasty (TKA). This can cause concern that infection is present. The purpose of our study was to establish the pattern of knee skin temperature following uncomplicated TKA. It was a prospective study carried out between 2001 and 2004. A pocket digital surface thermometer was used. A preliminary study established that the best site to measure knee skin temperature was superomedial to the patella and the best time was 12 noon. Patients with an increased risk of infection and those with a contralateral knee pathology or a previous surgery were excluded. Forty-eight patients fulfilled the inclusion criteria and consented to participate; the skin temperature of operated and contralateral knees was measured pre-operatively and daily during the first six weeks post-operatively. Measurements were also taken at 3, 6, 12 and 24 months following surgery. During the course of the study, patients developing complications of the operated knee or any pathology of the contralateral knee were excluded. Thirty-two patients completed the main study. Following surgery, systemic and both knees temperatures increased. Whereas systemic and contralateral knee temperatures settled within one week, the operated knee temperature took a longer time. The difference in temperature between the two knees had a mean value of +2.9°C at 7 days. This mean value decreased to +1.6°C at 6 weeks, +1.3°C at 3 months, +0.9°C at 6 months +0.3°C at 12 months and +0.04°C at 24 months. Following uncomplicated TKA, the operated knee skin temperature increases compared to the contralateral knee. This increase peaks at day 3 and diminishes slowly over several months; however, it remains statistically significant up to 6 months. These results correlate with the findings of previous studies that showed a prolonged elevation of inflammatory markers

Bilateral simultaneous total knee replacement surgery remains controversial with arguments for and against its use. Doing sequentially staged TKR's is a safer procedure and may have additional benefits as set out below. If both knees need to be replaced we have often seen that the symptoms of the contralateral knee improve after the one knee is replaced and that patients wait some time before having the opposite knee replaced. Materials:. 333 of 2084 patients having primary total knee replacements needing bilateral replacements were reviewed retrospectively. Results. 245 patients were seen initially with bilateral arthritis of the knee and needed bilateral TKR, while 88 patients developed arthritis in the contralateral knee following TKR. No patients had simultaneous bilateral TKR's; operations were done sequentially and the average time between the TKRs was 20.77 months with a range between 1.5–111 months. Most patients had the contralateral knee replaced within two years of the first knee replacement but 81 patients actually waited between 2 and 10 years before coming in for the second TKR. Conclusion:. It is possible to wait some time before it becomes necessary to replace the contralateral knee in patients who need bilateral TKRs and avoid the increased risk of bilateral simultaneous surgery. The delay not only reduces the cost for the first operation but also gives the second knee a longer time to failure. This is especially important in the typical patients who qualify for bilateral simultaneous TKR's i.e. the younger fitter patients

Aim. Patellofemoral Arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis. Methods. Our study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFJ with asymmetric trochlear component, performed between June 2007 and October 2018 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation. Results. A total of 128 PFA performed on 96 patients were evaluated. All patients were under regular follow up, and no patient was lost to follow up. Eighteen patients underwent simultaneous bilateral procedures, and 14 patients underwent PFA of the contralateral knee later. Median age at the time of surgery was 59 years (interquartile range 53 – 66 years); the median follow up period was 6 years (interquartile range 2.5 – 7 years). The Oxford Knee Score showed improvement from a median of 18 to 37. There were statistically significant improvements in functional outcome scores. Beverland satisfaction questionnaire revealed that 22.1 % (19/86) were ‘Very happy’ and 39.5% (34/86) were ‘Happy’ following the procedure. Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan-Meier method was 95.2% (95% confidence interval: 90.4%– 99.9%). Conclusion. This series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant related complications

Background. In this study, we assessed implant survivorship, patient satisfaction, and patient-reported functional outcomes at two years for patients implanted with a customized, posterior stabilized knee replacement system. Methods. Ninety-three patients (100 knees) with the customized PS TKR were enrolled at two centers. Patients’ length of hospitalization and preoperative pain intensity were assessed. At a single time point follow-up, we assessed patient reported outcomes utilizing the KOOS Jr., satisfaction rates, implant survivorship, patients’ perception of their knee and their overall preference between the two knees, if they had their contralateral knee replaced with an off-the-shelf (OTS) implant. Results. At an average of 1.9-years implant survivorship was found to be 100%. From pre-op until time of follow-up, we observed an average decrease of 5.4 on the numeric pain rating scale. Satisfaction rate was found to be high with 90% of patients being satisfied or very satisfied and 88% of patients reporting a “natural” perception of their knee some or all the time. Patients with bilateral implants mostly (12/15) stated that they preferred their customized implant over the standard TKR. The evaluation of KOOS Jr. showed an average score of 90 at the time of the follow up. Conclusion. Based on our results, we believe that the customized PS implant provides patients with excellent outcomes post-surgery. Moreover, a subset of patients with an OTS implant in one knee and a customized PS implant in the other, we observed a trend in patients preferring the customized PS device over their OTS counterparts

It is unclear why ACL rupture increases osteoarthritis risk, regardless of ACL reconstruction. Our aims were: 1) to establish the reliability and accuracy of a direct method of determining tibiofemoral contact in vivo with UO-MRI, 2) to assess differences in knees with ACL rupture treated nonoperatively versus operatively, and 3) to assess differences in knees with ACL rupture versus healthy knees. We recruited a convenience sample of patients with prior ACL rupture. Inclusion criteria were: 1) adult participants between 18–50 years old; 2) unilateral, isolated ACL rupture within the last five years; 3) if reconstructed, done within one year from injury; 4) intact cartilage; and 5) completed a graduated rehabilitation program culminating in return to sport or recreational activities. Participants were excluded if they had other ligament ruptures, osteoarthritis, an incompletely rehabilitated injury, were prohibited from undergoing MRI, or had a history of ACL re-rupture. Using the UO-MRI, we investigated tibiofemoral contact area, centroid location, and six degrees of freedom alignment under standing, weightbearing conditions with knees extended. We compared patients with ACL rupture treated nonoperatively versus operatively, and ACL ruptured knees versus healthy control knees. We assessed reliability using the intra-class correlation coefficient, and accuracy by comparing UO-MRI contact area with a 7Tesla MRI reference standard. We used linear mixed-effects models to test the effects of ACL rupture and ACL reconstruction on contact area. We used a paired t test for centroid location and alignment differences in ACL ruptured knees versus control knees, and the independent t test for differences between ACL reconstruction and no reconstruction. Analyses were performed using R version 3.5.1. We calculated sample size based on a previous study that showed a contact area standard deviation of 13.6mm2, therefore we needed eight or more knees per group to detect a minimum contact area change of 20mm2with 80% power and an α of 0.05. We recruited 18 participants with ACL rupture: eight treated conservatively and 10 treated with ACL reconstruction. There were no significant differences between the operative and nonoperative ACL groups in terms of age, gender, BMI, time since injury, or functional knee scores (IKDC and KOOS). The UO-MRI demonstrated excellent inter-rater, test-retest, and intra-rater reliability with ICCs for contact area and centroid location ranging from 0.83–1.00. Contact area measurement was accurate to within 5% measurement error. At a mean 2.7 years after injury, we found that ACL rupture was associated with a 10.4% larger medial and lateral compartment contact areas (P=0.001), with the medial centroid located 5.2% more posterior (P=0.001). The tibiae of ACL ruptured knees were 2.3mm more anterior (P=0.003), and 2.6° less externally rotated (P=0.010) relative to the femur, than contralateral control knees. We found no differences between ACL reconstructed and nonreconstructed knees. ACL rupture was associated with significant mechanical changes 2.7 years out from injury, which ACL reconstruction did not restore. These findings may partially explain the equivalent risk of post-traumatic osteoarthritis in patients treated operatively and nonoperatively after ACL rupture

Approximately 20% of patients undergoing primary unilateral total knee arthroplasty complain of severe pain in the contralateral knee, and 10% of patients who have had a primary total knee (TKA) undergo contralateral surgery within 1 year. The number of patients suitable for primary TKA is rising, and so is the need for simultaneous bilateral TKA (BTKA) procedures. The advantages of single-stage BTKA include its low complication rates, high patient satisfaction, and cost-effectiveness. Others believe that there is increased morbidity and mortality. The goal of reducing the exposure to repeated anaesthesia, total hospitalization and recovery time, and cost, while maintaining patient safety, is a laudable one. Our data suggest that bilateral TKA patients have a lower total operating time, use less pain medication, have a shorter hospital stay and lower overall treatment costs. The cohort of patients selected for bilateral surgery in our unit is younger and has fewer comorbidities than unilateral controls. They have a high satisfaction rate and no increase in complication or readmission rates. We have seen a higher blood transfusion rate but no increase in cardiac, thromboembolic or septic complications. The key to BTKA is patient selection and the implementation of efficient care and surgical pathways that includes a thorough pre-assessment, careful education and well-resourced aggressive post-operative physiotherapy. When appropriately applied, the benefits include a shorter overall recovery time and an accelerated return to everyday life and work

Purpose. the purpose of this study was to compare the rollback ratio in the bi-cruciate substituting BCS-TKA and the Oxford UKA. Methods. 20 subjects (28 knees) who were performed the BCS-TKA (Journey II: Smith and Nephew) and 24 subjects (29 knees) who were performed the Oxford UKA, were included in this study. Approximately 6 months after surgery, and when the subjects recovered their range of knee motion, following the Laidlow's method (The knee 2010), lateral radiographic imaging of the knee was performed with active full knee flexion. The most posterior tibiofemoral contact point was measured for evaluation of femoral rollback (Rollback ratio). Flexion angle was also measured using the same radiograph and the correlation of rollback and flexion angle was analyzed. As a control, radiographs of the contralateral knees of who were performed Oxford UKA were evaluated (29 knees). Results. The rollback ratios of the BCS-TKA, Oxford UKA, and the control knees were 37.9±4.9%, 35.7±4.2%, and 35.3±4.8% respectively from the posterior edge of the tibia. No significant difference in rollback ratio was observed. The flexion angles of the BCS-TKA, Oxford UKA, and the control knees were 121.8±8.4°, 125.4±7.5°, and 127±10.3°, respectively. No significant difference in knee flexion angle was observed. Significant correlation between rollback ratio and knee flexion angle was observed (p=0.002: Pearson's correlation coefficient =−0.384). Conclusion. In conclusion, BCS-TKA showed no significant difference of rollback ratio when compared with the control knees and the Oxford UKA knees. There is the possibility that the design of BCS-TKA could reproduce the native ACL and PCL function

Report of a case of migrating periprosthetic infection from a hip replacement to a contralateral knee joint undergoing a total knee replacement. We present a 74-year old female patient who underwent a total hip arthroplasty of the left hip after a subcapital fracture of the femur. Four months after the index procedure the patient presented with signs and symptoms of infection of the operated joint. Staph aureus and Enterococcus faecalis were recognized as the infecting bacteria. The implants were removed, cement spacers were placed and a total hip arthroplasty was performed again after three months. Unfortunately, infection ensued again and the patient underwent three more procedures until the joint was considered clean and t he hip remained flail without implants. The patient elected to undergo a total knee arthroplasty due to severe osteoarthritis of right knee. Intraoperatively tissue samples were taken and sent for cultures which identified Enterococcus faecalis present in the knee joint. Enterococcus migrated from the infected hip to nonoperated knee joint. Intravenous antibiotics were administered for three weeks but the knee presented with infection of the arthroplasty ten months after its insertion. The implants were removed the joint was debrided and cement spacers were inserted. The patient decided not to proceed with another procedure and she remains with the cement spacers in her knee. Rare report of migrating periprosthetic infection. Nosocomial enterococci acquired resistance cannot be ruled out. Unique characteristics in enterococci antibiotic resistance and biofilm formation

Total knee arthroplasty (TKA) is currently one of the most common elective surgical procedures in the United States. The increase in the proportion of younger patients in receipt of surgery, in concert with a dramatic rise in the incidence of obesity, has contributed to the on-going, exponential increase in the number of arthroplasties performed annually. Despite materials advances for implants, the U.S. revision burden has remained static for the last decade. According to the 2013 CMS MEDPAR file the typical CMS reimbursement falls far short of costs incurred by the hospital, resulting in an average net loss of revenue of $9,539; and over 90% of hospitals lose money for every revision case performed. Today, approximately 5% of all primaries performed will result in an early revision (< 3 years). In order to understand ways with which to mitigate the incidence of early revision due to mechanical complications, a multicentric group of sensor-assisted patients was follow-up out to 3 years. In this study, 278 sensor-assisted patients were followed out to 3 years. The intraoperative devices used in this study contain microsensors and a processing unit. Kinetic and center of load location data are projected, in real-time, to a screen. Because of the wireless nature of the intraoperative sensors, the patella can be reduced, and kinematic data can be evaluated through the range of motion. For each patient, the soft-tissue envelope was balanced to within a mediolateral differential of 15 lbf., through the ROM, as per the suggestion of previously reported literature. The average patient profile indicates: age = 69.7 years, BMI = 30.4, gender distribution = 36% male/64% female. Any adverse event within the 3-year follow-up interval was captured. By 3 years, 1 patient in this population has required revision surgeon due to mechanical complicatons. Overall adverse events included: pain in hip (3), pain in contralateral knee (2), wound drainage (3), DVT (1), death (1), stiffness in operative knee (2), infection (3), global pain (2), back pain (2). Based on the average reported number of early revisions that occur in the U.S. (5% of primaries), it was anticipated for this patient group to require approximately 13 revisions by the 3-year follow-up interval. Using 2013 CMS MEDPAR data, these 13 revisions would have resulted in $124,007 cost-to-hospital. However, only 1 revision (0.4%) was observered, therefore $114,468 in additional costs were spared for the aggregate of participating hospitals. This data suggests that the incorporation of kinetic sensors in TKA may assist the surgeon in achieving soft-tissue balance and thereby avoiding adverse mechanical complications that require surgical intervention

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

We conducted a randomized controlled trial (RCT) to investigate if iodine impregnated incision drapes (IIID) increases bacterial recolonization rates compared to no drape use under conditions of simulated total knee arthroplasty (TKA) surgery. Background: To prevent surgical site infection (SSI), one of the important issues is managing the patient´s own skin flora. Many prophylactic initiatives have been suggested, including the use of IIID. IIID has been debated for many years and was deemed ineffective in preventing SSI in a recent systematic review [1], while some evidence suggests a potential increase in postoperative infection risk, as a result of IIID use [2]. IIID is sparsely investigated in orthopaedic surgery. An increase in the number of viable bacteria in the surgical field of an arthroplasty operation has a potential to increase the risk of SSI in an otherwise elective and clean procedure [3]. 20 patients scheduled for TKA were recruited. Each patient had one knee randomized for draping with IIID [4] while the contralateral knee was left bare, thus the patients acted as their own controls. Operating theater settings with laminar airflow and standard perioperative procedures were simulated. Sampling was performed with the cup-scrup technique [5] using appropriate neutralizers. Samples were collected from the skin of each knee prior to disinfection and on 2 occasions after skin-preparation, 75 minutes apart. Bacterial quantities were estimated by spread plating with 48-hour aerobic incubation. Outcome was measured as colony forming units per square centimeter of skin. We used Wilcoxon signed-rank test for comparative analysis within and between knees. Following skin-disinfection we found no significant difference in bacterial quantities between the intervention and the control knee (p = 0.388). Neither did we see any difference in bacterial quantities between the two groups after 75 minutes of simulated surgery (p = 0.367). When analyzed within the intervention and control group, bacterial quantities had not significantly increased at the end of surgery when compared to baseline, thus no recolonization was detected (p = 0.665 and 0.609, respectively). Iodine impregnated incision drapes did not increase bacterial recolonization rates in simulated TKA surgery. Thus, the results of this RCT study does not support the hypothesis that iodine impregnated incision drapes promotes bacterial recolonization and postoperative infection risk

Most discussions of alignment after TKA focus on defining “malalignment”; the prefix mal- is derived from Latin and refers to bad, abnormal or defective and thus by definition malalignment is bad, abnormal or defective alignment. No one then wants a “malaligned” knee. The intellectually curious, however, might switch the focus to the other end of the spectrum and ask what does an ideally aligned knee look like in 2015? Is there really one simple target value for alignment in all patients undergoing TKA? Is that target broad (zero +/−3 degrees mechanical axis) or is it a narrow target in which a penalty, in regard to durability or function, is incurred as soon as you deviate even 1 degree? Is that ideal target the same if we are evaluating the functional performance of the TKA versus the durability of the TKA or could there be 2 different targets, one that maximises function and one that maximises durability? Is that target adequately described by a single 2-dimensional value (varus/valgus alignment in the frontal plane) as measured on a static radiograph? Is that value the same if the patient has a fixed pelvic obliquity, a varus thrust in the contralateral knee or an abnormal foot progression angle?. It is revealing to ask “do we understand TKA alignment better in 2015 than in 1979…?” Maybe not. We allowed ourselves over the past 2 decades to be intellectually complacent in regard to questions of ideal alignment after TKA. The constraints on accuracy imposed by our standard total knee instruments and the constraints on assessment imposed by 2-dimensional radiographs made broad, simple targets like a mechanical axis +/− 3 degrees reasonable starting points yet we have not further worked to verify if we can do better. It is naïve to think that the complex motion at the knee occurring in 6-dimensions over time can be reduced to a single static target value like a neutral mechanical axis and have strong predictive value in regard to the success or failure of an individual TKA. We assessed 399 knees of 3 different modern cemented designs at 15 years and found that factors other than alignment were more important than alignment in determining the 15-year survival. Until more precise alignment targets can be identified for individual patients or sub-groups of patients then a neutral mechanical axis remains a reasonable surgical goal. However, the traditional description of TKA alignment as a dichotomous variable (aligned versus malaligned) defined around the broad, generic target value of 0 +/− 3 degrees relative to the mechanical axis is of little practical value in predicting the durability or function of modern TKA

Introduction. In a previous study of subjects with no history of lower extremity injury or disease we found a linear relationship between body weight and peak hip, knee, and ankle joint forces during the stance phase of gait. To investigate the effect of total knee arthroplasty (TKA) on forces in the operated joints as well as the other joints of the lower extremities, we tested TKA subjects during gait and performed inverse dynamics analyses of the results. Materials and Methods. TKA subjects (3 M, 1 F; 58 ± 5 years; body mass index range (BMI): 26–36 kg/m. 2. ) participated in this investigation following institutional review board approval and informed consent. One subject had bilateral knee replacement. Each patient received the same implant design (4 PS, 1 CR). Data from previously tested control subjects (8 M, 4 F; 26 ± 4 years; BMI: 20–36 kg/m. 2. ) were used for comparison. Retro-reflective markers were placed over bony landmarks of each subject. A nine-camera video-based opto-electronic system was used for 3D motion capture as subjects walked barefoot at a self-selected speed on a 10 meter walkway instrumented with three force plates. Data were imported into a 12-body segment multibody dynamics model (AnyBody Technology) to calculate joint forces. Each leg contained 56 muscles whose mechanical effect was modeled by 159 simple muscle slips, each consisting of a contractile element. The models were scaled to match each subject's anthropometry and BMI. For the control subjects, only one limb was used in determining the relationship between body mass and peak joint force at the hip, knee, and ankle. For the TKA subjects, the peak joint forces were calculated for both the TKA limb and the contralateral limb. Results. Figure 1 shows the knee joint forces for the TKA subjects’ operated (red triangles) and contralateral knees (diamonds) along with the values for the control subjects (circles). Knee joint forces for the TKA subjects fell within or near the upper and lower 95% confidence intervals (dashed lines) of the mean regression lines (solid lines) for the control subjects. Three patients had other lower limb complications (osteoarthritis, ankle surgery). One subject favored the operated limb and another the non-operated limb, as ascertained from the corresponding hip (Figure 2) and ankle joint forces (Figure 3). Discussion. Modeling and simulation can be used to indirectly estimate joint forces in the implanted and non-operated joints. Our gait-lab derived inverse dynamics simulations suggest that joint forces following TKA fall within or near the normal range over a wide range of body weights and that the linear dependence between joint force and body weight applies to the implanted as well as non-implanted joints

Purpose. It is well known that meniscus extrusion is associated with structural progression of knee OA. However, it is unknown whether medial meniscus extrusion promotes cartilage loss in specific femorotibial subregions, or whether it is associated with a increase in cartilage thickness loss throughout the entire femorotibial compartment. We applied quantitative MRI-based measurements of subregional cartilage thickness (change) and meniscus position, to address the above question in knees with and without radiographic joint space narrowing (JSN). Methods. 60 participants with unilateral medial OARSI JSN grade 1–3, and contralateral knee OARSI JSN grade 0 were drawn from the Osteoarthritis Initiative. Manual segmentation of the medial tibial and weight-bearing medial femoral cartilage was performed, using baseline and 1-year follow-up sagittal double echo steady-state (DESS) MRI, and proprietary software (Chondrometrics GmbH, Ainring, Germany). Segmentation of the entire medial meniscus was performed with the same software, using baseline coronal DESS images. Longitudinal cartilage loss was computed for 5 tibial (central, external, internal, anterior, posterior) and 3 femoral (central, external, internal) subregions. Meniscus position was determined as the % area of the entire meniscus extruding the tibial plateau medially and the distance between the external meniscus border and the tibial cartilage in an image located 4mm posterior to the central image (a location commonly used for semi-quantitative meniscus scoring). The relationship between meniscus position and cartilage loss was assessed using Pearson (r) correlation coefficients, for knees with JSN and without JSN. Results. The percentage of knees showing a quantitative value of >3mm medial meniscus extrusion was 50% in JSN knees, and only 12% in noJSN knees. The 1-year cartilage loss in the medial femorotibial compartment was 74±182µm (2.0%) in JSN knees, and 26±120µm (0.8%) in noJSN knees. There was a significant correlation between cartilage loss throughout the entire femorotibial compartment (MFTC) and extrusion area in JSN knees but not for noJSN knees. Also, the extrusion distance measured 4mm posterior to the central slice was not significantly correlated with MFTC cartilage loss. The strongest (negative) correlation between meniscus position and subregional femorotibial cartilage loss (r=−0.36) was observed for the external medial tibia. In contrast, no significant relationship was seen in the central tibia. No significant relationship was found in other tibial subregions, except for the anterior medial tibia, but only in JSN knees (r=−0.27). Correlation coefficients for the femoral subregions were generally smaller than those for tibial subregions, with only the internal medial weight-bearing femur attaining statistical significance (r =−0.26). Conclusions. The current results show that the relationship between meniscus extrusion and cartilage loss differs substantially between femorotibial subregions. The correlation was strongest for the external medial tibia, a region that is physiologically covered by the medial meniscus. It was less for other tibial and femoral subregions, including the central medial tibia, a region that exhibited similar rates of cartilage loss as the external subregion. The findings suggest that external tibia may be particularly vulnerable to cartilage tissue loss once the meniscus extrudes and the surface is “exposed” to direct, non-physiological, cartilage-cartilage contact

This prospective longitudinal study compares the results of isolated endoscopic ACL reconstruction utilizing 4-strand hamstring tendon (HT) or patellar tendon (PT) autograft over a 15-year period with respect to re-injury, clinical outcomes and the development of osteoarthritis. 90 consecutive patients with isolated ACL rupture were reconstructed with a PT autograft and 90 patients received HT autograft, with an identical surgical technique. Patients were assessed at 2, 5, 7, 10 and 15 years. Assessment included the IKDC Knee Ligament Evaluation including radiographic evaluation, KT1000, Lysholm Knee Score, kneeling pain, and clinical outcomes. Subjects who received the PT graft had significantly worse outcomes compared to those who received the HT graft at 15 years for the variables of radiologically detectable osteoarthritis (p=0.03), motion loss (p=0.01), single leg hop test (p=0.002), participation in strenuous activity (p=0.05), and kneeling pain (p=0.04). There was no significant difference between the HT and PT groups in overall IKDC grade (p=0.31). ACL graft rupture occurred in 16% of HT group and 8% of the PT group (p=0.07). ACL graft rupture was associated with non-ideal tunnel position (odds ratio 5.0) and males (odds ratio 3.2). Contralateral ACL rupture occurred in significantly more PT patients (24%) than HT patients (12%) (p=0.03), and was associated with age < 18 years (odds ratio 4.1) and the patellar tendon graft (odds ratio 2.6). Radiologically detectable osteoarthritis at 15 years was associated with the PT graft (odds ratio 2.3). Significant differences have developed in the groups at 15 years after surgery which were not seen at earlier reviews. Compared to the HT Group, the PT group had significantly worse outcomes with respect to radiological osteoarthritis, extension loss and functional tests but no significant difference in laxity was identified. There was a high incidence of ACL injury after reconstruction, to both the reconstructed and the contralateral knee