Total Knee Arthroplasty Cohort Research Articles

Computational tibial bone remodeling over a population after total knee arthroplasty: A comparative study.

Periprosthetic bone loss is an important factor in tibial implant failure mechanisms in total knee arthroplasty (TKA). The purpose of this study was to validate computational postoperative bone response using longitudinal clinical DEXA densities. Computational remodeling outcome over a population was obtained by incorporating the strain‐adaptive remodeling theory in finite element (FE) simulations of 26 different tibiae. Physiological loading conditions were applied, and bone mineral density (BMD) in three different regions of interest (ROIs) was considered over a postoperative time of 15 years. BMD outcome was compared directly to previously reported clinical BMD data of a comparable TKA cohort. Similar trends between computational and clinical bone remodeling over time were observed in the two proximal ROIs, with most rapid bone loss taking place in the initial months after TKA and BMD starting to level in the following years. The extent of absolute proximal BMD change was underestimated in the FE population compared with the clinical subject group, which might be the result of significantly higher initial clinical baseline BMD values. Large differences in remodeling response were found in the distal ROI, in which resorption was measured clinically, but a large BMD increase was predicted by the FE models. Multiple computational limitations, related to the FE mesh, loading conditions, and strain‐adaptive algorithm, likely contributed to the extensive local bone formation. Further research incorporating subject‐specific comparisons using follow‐up CT scans and more extensive physiological knee loading is recommended to optimize bone remodeling more distal to the tibial baseplate.

The incidence of acute myocardial infarction after elective spinal fusions or joint replacement surgery in the United States: a large-scale retrospective observational cohort study in 322,585 patients

BackgroundAcute myocardial infarction (AMI) is an uncommon but fatal complication among patients undergoing elective spinal fusion surgery (SF), total hip arthroplasty (THA), and total knee arthroplasty (TKA). Our objective was to estimate the incidence of AMI among adults undergoing elective SF, THA, and TKA in different post-operative risk windows and characterize high-risk sub-populations in the United States.MethodsA retrospective cohort study was conducted using data from a longitudinal electronic healthcare record (EHR) database from January 1, 2007 to June 30, 2018. ICD codes were used to identify SF, THA, TKA, AMI, and selected clinical characteristics. Incidence proportions (IPs) and 95% confidence intervals were estimated in the following risk windows: index hospitalization, ≤ 30, ≤ 90, ≤ 180, and ≤ 365 days post-operation.ResultsA total of 67,533 SF patients, 87,572 THA patients, and 167,480 TKA patients were eligible for the study. The IP of AMI after SF, THA, and TKA ranged from 0.36, 0.28, and 0.25% during index hospitalization to 1.05, 0.93, and 0.85% ≤ 365 days post-operation, respectively. The IP of AMI was higher among patients who were older, male, with longer hospital stays, had a history of AMI, and had a history of diabetes.ConclusionThe IP of post-operative AMI was generally highest among the SF cohort compared to the THA and TKA cohorts. Additionally, potential high-risk populations were identified. Future studies in this area are warranted to confirm these findings via improved confounder control and to identify effect measure modifiers.

Postoperative Complications in Patients With Hereditary Hemochromatosis Undergoing Total Joint Arthroplasty: A Matched Cohort Analysis.

The purpose of this study is to determine differences in the rates of 90-day postoperative complications and 2- and 5-year surgical outcomes between patients with and without hereditary hemochromatosis (HH) after total joint arthroplasty (TJA). Patients who underwent primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) from 2010 to 2018 were identified in a national database (PearlDiver Technologies) using Current Procedural Terminology and International Classification of Diseases-9/10 codes. Patients with a history of HH were identified within the THA and TKA cohorts and matched with non-HH patients based on age, sex, Charlson Comorbidity Index, smoking status, and obesity (body mass index > 30). Ninety-day medical complications assessed included renal failure, arrhythmia, bleeding complications, blood transfusion, pneumonia, stroke, deep vein thrombosis, liver failure, heart failure, pulmonary embolism, sepsis, surgical site infection, wound dehiscence, readmission rate, and death. Two- and 5-year surgical complications assessed included all-cause revision, prosthetic joint infection, implant loosening, joint stiffness, and manipulation under anesthesia. All complications were analyzed using bivariate analysis and logistic regression, with significance set at P < 0.05. Compared with non-HH patients, patients with HH had higher rates of stiffness at 2 and 5 years after THA (all, P < 0.001), as well as higher rates of aseptic loosening at 5 years after TKA (P = 0.036). However, patients with HH undergoing THA and TKA had no notable difference in 90-day postoperative complications when compared with non-HH patients. Compared with non-HH patients, patients with HH undergoing TJA were shown to have worse 2- and 5-year surgical outcomes, without any increased risk of 90-day medical complications. These findings may be useful for surgical decision making for patients with HH undergoing TJA. This study addresses a paucity in the current literature concerning the complication profile in HH patients with destructive joint arthropathy undergoing joint arthroplasty surgery.

Outpatient total hip and knee arthroplasty exhibit similar early complication rates to inpatient procedures

PurposeThe purpose of this study was to compare early post-operative complications and readmissions between total joint arthroplasty (TJA) patients completed as outpatient versus inpatient procedures. MethodsA review of 2648 primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients between 2015 and 2019 was performed. Patients who underwent same-day discharge were matched to the inpatient cohort using age, gender, body mass index (BMI), and smoking status. American Society of Anesthesiologists (ASA) Scores were calculated for the two cohorts. A total of 234 matched pairs (468 knees) for the TKA cohort and 132 matched pairs (264 hips) for the THA cohort were identified. Data was collected for six months after surgery for 30- and 90-day readmissions, the occurrence of reoperations, revisions, deep vein thrombosis (DVT), pulmonary embolism (PE), falls within 90 days, fractures, infections and dislocations. ResultsThe average age for TJA patients was 60 years, with an average BMI of 32, 58% females, and 51.5% who reported never smoking. Post-operative fall risk was higher in the inpatient TKA cohort compared to the same-day cohort (3.0% vs 0.4%, p = 0.032) as was the risk of 90-day readmission (6.0% vs 2.1%, p = 0.034), respectively. These differences were also observed in the combined THA and TKA cohorts. ConclusionsWe report no increase in reoperations, revisions, 30 or 90-day readmissions, deep vein thrombosis (DVT), pulmonary embolism (PE), fractures, infections or dislocations in the outpatient cohort. Early complications and readmissions of patients who underwent TJA as same-day surgeries compared favorably to a matched cohort of inpatients.

The Effects of Depression and Anxiety on 90-day Readmission Rates After Total Hip and Knee Arthroplasty.

BackgroundPatients undergoing total joint arthroplasty have higher rates of anxiety, depression or anxiety and depression than the general population and higher costs of care, which lead to higher levels of postoperative dissatisfaction and readmission rates. We evaluated the readmission rates of patients undergoing total hip or knee arthroplasty with diagnoses of anxiety, depression, or both.MethodsOur hospital’s prospectively collected data from Michigan’s statewide total joint database were reviewed from 2013 to 2018. Rates of anxiety, depression or anxiety and depression were determined based on preoperative anxiolytic or antidepressant medications using National Drug Codes.ResultsA total of 4107 cases were included. Of which 4.28% had a readmission within the 90-day global period, and 12% had a history of depression or anxiety or both. For the entire cohort, those on anxiolytic medication were 153% more likely to be readmitted than those not on medication (P = .017). When comparing total hip arthroplasty (THA) or total knee arthroplasty (TKA), patients taking anxiolytic medication and undergoing TKA were 120% more likely to undergo readmission within 90 days (P = .021). Patients on depression medication alone were not at increased risk of readmission in the TKA cohort (P = .991). For THA, neither diagnosis appeared a risk factor for readmission (P = .852).ConclusionsPatients with depression, anxiety, or both undergoing TKA were at a statistically significant risk of readmission within 90 days compared with patients without these diagnoses. Anxiety and depression were both risk factors for readmission, but anxiety appeared to have a more significant impact. Patients undergoing THA on the other hand did not appear to share this risk profile.

Patient expectations and satisfaction in robotic-assisted total knee arthroplasty: a prospective two-year outcome study.

The impact of fulfillment of patient expectations throughout recovery on satisfaction in total knee arthroplasty (TKA) is not well understood. Utilizing a standardized TKA method with a robotically assisted (RA) platform, we investigated the impact of expectation fulfillment at 3-month (M) and 6-M on 1-year (Y) and 2-Y satisfaction. We hypothesize that early fulfillment of patient expectations is associated with improved midterm patient satisfaction. We also compare improvements in outcomes with RA-TKA to those of a recent large national TKA cohort study to determine whether RA-TKA meets or exceeds the current standard of care. One hundred six patients were prospectively enrolled and underwent robotic-assisted TKA by a single surgeon using the OMNIBotics system. Patients completed KOOS and New Knee Society Score (KSS) preoperatively and at 3M, 6M, 1Y, and 2Y postoperatively. Expectation fulfillment was subdivided into patients who were below or above the average expectation score pre-operatively, or fulfillment of expectation score at 3M and 6M post TKA. The satisfaction of each group was then compared at 1Y and 2Y post TKA. Study cohort outcomes were compared to contemporary literature from the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) database. Patients with greater than average KSS expectation fulfillment at 3M reported significantly higher KSS satisfaction scores at 1Y (34.9 ± 5.3 vs 30.6 ± 6.7, p = 0.0012), and patients with greater than average 6M expectation fulfillment reported improved satisfaction at 1Y (33.9 ± 5.9 vs 31.1 ± 6.7, p = 0.0330) and 2Y (35.2 ± 4.8 vs 32.4 ± 6.8, p = 0.0323). When compared to the FORCE-TJR database, no significant differences in post-operative KOOS outcomes were observed except for Sports and Recreation, for which the RAS group demonstrated higher scores (65.5 ± 30.0 vs 53.0 ± 27.1 p < 0.0001); however, the study cohort reported significantly greater improvements in KOOS Pain, Symptoms, Sports and Recreation, and Quality of Life at multiple time points up to 2years post TKA. High early-expectation fulfillment was associated with improved satisfaction at 1Y and 2Y, indicating the importance of managing patient-specific post-operative care to ensure patients reach their pre-operative goals. Greater improvements in all KOOS sub-scores and in absolute Sports and Recreation at 1Y and 2Y were observed in this robotic-assisted cohort compared to a large contemporary database, indicating that RAS meets or exceeds current standard of care benchmarks for patient-reported outcomes.

Effect of tibial cut angle in gap balanced LCS total knee replacement on postoperative knee funcion: A retrospective comparison study

Background: Although total knee arthroplasty (TKA) is one of the most successful operations in orthopaedic surgery, still approximately 20% of these patients have chronic unexplained pain which affect their life’s quality and post-operative expectations. The New Jersey low contact stress (LCS) knee system (LCS; DePuy Orthopaedics Inc., Warsaw, IN, USA) is one of the most effective knee designs with a well-known long track record. The surgical technique used is a gap balance technique which references the femoral component rotation to a well-designed tibial cut while maintaining soft tissue balance via appropriate tensioning of collateral ligaments. Aim of this study is to look at any relationship between tibial cut coronal orientation on x-rays and patients satisfaction in relation to pain and function using the validated Oxford Knee Score (OKS). Hypothesis: A varus tibial cut >3? in LCS TKA can result in femoral component internal rotation, patellar maltracking and chronic knee pain with suboptimal functional results. Methods: A single surgeon’s TKA cohort using the LCS system was retrospectively evaluated from March 2017 to March 2020. We identified two cohorts of patients, one with a tibial cut angle on x-rays 3? (41 TKAs). They received LCS TKA for right or left knee symptomatic end stage arthritis. We measured the tibial cut angle on antero-posterior (AP) x-rays and we obtained updated OKS by discussion over telephone (due to COVID-19 restrictions) with patients. We analysed our data for the two patient cohorts to look for any statistically significant functional difference. Results: 100 patients coronal x-rays were finally included in the study. 59 patients were identified to have tibial cut angle 3?. The average age of the patients was 69.45(53-81 years), average time since surgery 19.4 months (7-41months), and average OKS of 45.88. There was statistically significant difference in OKSs with females scoring less than males, with the former avera

Unexpected high rate of revision of a modern cemented fixed bearing modular posterior-stabilized knee arthroplasty.

To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period. This is a retrospective study of 166 (154 patients) consecutive cemented, fixed bearing, posterior-stabilized (PS) TKAs (ATTUNE) at one hospital performed by five surgeons. These were compared with a reference cohort of 511 knees (470 patients) of other designs (seven manufacturers) performed at the same hospital by the same surgeons. There were no significant differences in age, sex, BMI, or follow-up times between the two cohorts. The primary outcome was revision performed or pending. In total, 19 (11.5%) ATTUNE study TKAs have been revised at a mean 30.3 months (SD 15), and loosening of the tibial component was seen in 17 of these (90%). Revision is pending in 12 (7%) knees. There was no difference between the 31 knees revised or with revision pending and the remaining 135 study knees in terms of patient characteristics, type of bone cement (p = 0.988), or individual surgeon (p = 0.550). In the reference cohort, there were significantly fewer knees revised (n = 13, 2.6%) and with revision pending (n = 8, 1.5%) (both p < 0.001), and only two had loosening of the tibial component as the reason for revision. This new TKA design had an unexpectedly high early rate of revision compared with our reference cohort of TKAs. Debonding of the tibial component was the most common reason for failure. Additional longer-term follow-up studies of this specific component and techniques for implantation are warranted. The version of the ATTUNE tibial component implanted in this study has undergone modifications by the manufacturer. Cite this article: Bone Joint J2021;103-B(6 Supple A):137-144.

Early Recovery Following Total and Unicompartmental Knee Arthroplasty Assessed Using Novel Patient-Reported Measures

BackgroundThe early postoperative recovery period following unicompartmental (UKA) and total knee arthroplasty (TKA) is an important area for research with increasingly sensitive metrics and new technologies. This study uses 2 recently developed patient-reported scores to compare the recovery following UKA and TKA. MethodsTwo consecutive cohorts of 37 UKAs and 33 TKAs completed the Oxford Arthroplasty Early Recovery Score (OARS) and the Oxford Arthroplasty Early Change Score (OACS) on days 1, 2, 3, 7, 14, and week 6. The Short Form-36 version 2 was also completed on weeks 1, 2, and 6. Improvements within cohorts and comparisons between cohorts were assessed. ResultsFor both UKA and TKA the speed of recovery was rapid early on and then progressively decreased. At all time points, the UKA cohort reported similar or significantly better scores than the TKA cohort. The overall OARS (P < .001) showed that UKA recovered, shown as improvement on the OARS, 2-3 times faster than TKA. OARS subscales demonstrated that UKA had better Function/Mobility (P = .003) particularly early in the recovery, and better Nausea/Feeling Unwell (P < .001) and Fatigue/Sleep (P = .009) later in the recovery. UKA also had less pain at 2 weeks (P = .03). There was no significant difference between UKA and TKA OACS. UKA had significantly better scores in 3 of the 8 Short Form-36 domains, with the largest difference being in Role-Emotional (P = .003). ConclusionThe OARS is useful for the assessment of postoperative recovery. This study provides direct evidence that recovery following UKA is better and 2-3 times faster than following TKA. All differences may be explained by the less invasive nature of UKA.

Les pertes sanguines sont 1,38 à 2,17 fois plus importantes après reprise de PTG qu’après PTG primaire : analyse rétrospective de 898 cas

BackgroundThere are a number of factors that influence blood loss during and after primary total knee arthroplasty (TKA) and revision TKA (rTKA). The purpose of this study was to provide a factorial assessment that would aid surgeons in managing expected blood loss in rTKA, when compared to TKA. The first question asked was the blood loss and transfusions between TKA and rTKA and the second question were risk factors for blood loss after rTKA. HypothesisBlood loss in any rTKA is higher than in TKA by a factor of 2. Patients and methodsA retrospective single-center consecutive series of rTKA between 2006 and 2018 was performed. Based on the rTKA types identified in joint registries, 4 rTKA cohorts were created: aseptic minor rTKA, aseptic major rTKA, 1st stage, and 2nd stage septic rTKA. A consecutive TKA cohort from the same study period was used to create a propensity score matched cohort with the aseptic major rTKA cohort. ResultA total of 622 rTKA were identified. Aseptic major rTKA had double the median blood loss than TKA. The lowest blood loss was observed in the TKA group followed by aseptic minor rTKA, and the highest in 2nd stage septic rTKA. The median total blood loss was higher in all rTKA by a factor ranging between 1.38 and 2.17. Higher age, female gender, lower preoperative hemoglobin, chronic heart disease and history of myocardial infarction were risk factors for increased blood loss. The type of rTKA performed was not predictive of blood loss in the linear regression analysis. DiscussionBlood loss after rTKA is 1.38- to 2.17-fold higher than after TKA. The blood loss observed in 2nd stage septic rTKA and aseptic major rTKA was the highest. Older, female patients, with a low preoperative hemoglobin were identified to be at the highest risk of blood loss after rTKA. Strategies for further blood loss reductions need to be utilized to the fullest extent for these procedures. Level of evidenceIII; retrospective prognostic study.

The economic impact of periprosthetic infection in total knee arthroplasty.

BackgroundCurrently, the gold standard treatment for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is 2-stage revision, but few studies have looked at the economic impact of PJI on the health care system. The objective of this study was to obtain an accurate estimate of the institutional cost associated with the management of PJI in TKA and to assess the economic impact of PJI after TKA compared to uncomplicated primary TKA.MethodsWe identified consecutive patients in our institutional database who had undergone 2-stage revision TKA for PJI between 2010 and 2014 and matched them on age and body mass index with patients who had undergone uncomplicated primary TKA over the same period. We calculated all costs associated with the 2 procedures and compared mean costs, length of stay, clinical visits and readmission rates between the 2 groups.ResultsThere were 73 patients (mean age 68.8 [range 48–91] yr) in the revision TKA cohort and 73 patients (mean age 65.9 [range 50–86] yr) in the primary TKA cohort. Two-stage revision surgery was associated with a significantly longer hospital stay (mean 22.7 d v. 3.84 d, p < 0.001), more outpatient clinic visits (mean 8 v. 3, p < 0.001), more readmissions (29 v. 0, p < 0.001) and higher overall cost (mean $35 429.97 v. $6809.94, p < 0.001) than primary TKA.ConclusionTreatment for PJI after TKA has an enormous economic impact on the health care system. Our data suggest a fivefold increase in expenditure in the management of this complication compared to uncomplicated primary TKA.

Early Survivorship of Newly Designed Highly Porous Metaphyseal Tibial Cones in Revision Total Knee Arthroplasty.

BackgroundMetaphyseal cones provide durable fixation in revision total knee arthroplasty (TKA). However, there is a paucity of data on the outcomes of a new porous cone design. As such, the goal of this study was to analyze the early survivorship in patients undergoing revision TKA with this cone.MethodsWe retrospectively reviewed 163 revision TKAs with a newly designed porous tibial cone from 2016 to 2018. Mean age was 67 years, and mean body mass index was 33 kg/m2. Minimum follow-up duration was 2 years. Most patients were revised for aseptic loosening (46%), 2-stage periprosthetic joint infection (PJI) reimplantation (28%), or instability (15%). Most were varus-valgus constrained (65%) or hinged (32%) constructs. The majority had hybrid tibial stem fixation (74%). A multivariate Cox regression analysis was used to identify risk factors for reoperation.ResultsSurvivorship free from re-revision for aseptic loosening, any nonmodular revision, and any reoperation was 100%, 96%, and 86% at 2 years, respectively. No patients were revised for aseptic loosening. Six (4%) tibial cones were removed for PJI, one of which was loose. There were 23 reoperations (14%), most commonly for PJI (10%). Multivariate analysis identified PJI reimplantation (hazard ratios [HR] = 4.2, P = .002), males (HR = 2.9, P = .02), and hinged constructs (HR = 2.7, P = .02) as significant risk factors for reoperation.ConclusionsIn a complex revision TKA cohort with a new highly porous tibial cone, in which most patients received hybrid stem fixation and nonlinked and linked constraint, there was 100% survival free from re-revision for aseptic loosening at 2 years. Longer term follow-up is required.

Blood loss after revision knee arthroplasty is 1.38- to 2.17-fold higher than after primary knee arthroplasty: A retrospective analysis of 898 cases

BackgroundThere are a number of factors that influence blood loss during and after primary total knee arthroplasty (TKA) and revision TKA (rTKA). The purpose of this study was to provide a factorial assessment that would aid surgeons in managing expected blood loss in rTKA, when compared to TKA. The first question asked was the blood loss and transfusions between TKA and rTKA and the second question was risk factors for blood loss after rTKA. HypothesisBlood loss in any rTKA is higher than in TKA by a factor of 2. Patients and methodsA retrospective single-centre consecutive series of rTKA between 2006 and 2018 was performed. Based on the rTKA types identified in joint registries, 4 rTKA cohorts were created: aseptic minor rTKA, aseptic major rTKA, 1st stage, and 2nd stage septic rTKA. A consecutive TKA cohort from the same study period was used to create a propensity score matched cohort with the aseptic major rTKA cohort. ResultA total of 622 rTKA were identified. Aseptic major rTKA had double the median blood loss than TKA. The lowest blood loss was observed in the TKA group followed by aseptic minor rTKA, and the highest in 2nd stage septic rTKA. The median total blood loss was higher in all rTKA by a factor ranging between 1.38 and 2.17. Higher age, female gender, lower preoperative hemoglobin, chronic heart disease and history of myocardial infarction were risk factors for increased blood loss. The type of rTKA performed was not predictive of blood loss in the linear regression analysis. DiscussionBlood loss after rTKA is 1.38 to 2.17-fold higher than after TKA. The blood loss observed in 2nd stage septic rTKA and aseptic major rTKA was the highest. Older female patients, with a low preoperative hemoglobin, were identified to be at the highest risk of blood loss after rTKA. Strategies for further blood loss reductions need to be utilised to the fullest extent for these procedures. Level of evidenceIII; retrospective prognostic study.

Is There a Synergistic Effect of Topical Plus Intravenous Tranexamic Acid Versus Intravenous Administration Alone on Blood Loss and Transfusions in Primary Total Hip and Knee Arthroplasties?

BackgroundThe optimal route and dosing regimen of tranexamic acid (TXA) in primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unclear. As such, we sought to analyze if there was a synergistic effect of intravenous (IV) and topical TXA on blood loss and transfusions.MethodsWe retrospectively analyzed 6720 primary TKAs and 6559 THAs performed from February 1, 2016 to December 31, 2019 at a single institution in patients who received a double IV dose (6159 TKAs and 6276 THAs) compared with a combined single IV and topical dose (561 TKAs and 283 THAs) of TXA. Multivariate logistic regression models, adjusting for age, body mass index, American Society of Anesthesiologists class, preoperative hemoglobin, and TXA administration, were performed for significant variables from a univariate analysis.ResultsIn the TKA cohort, the mean total blood loss was statistically similar for double IV (305 mL, 95% confidence interval [CI] = 301-310 mL) TXA compared with combined TXA (310 mL, 95% CI = 299-321 mL) (P = .43). Furthermore, there was no difference in the rate of transfusion (odds ratio = 1.23, 95% CI = 0.57-2.67, P = .598). In the THA cohort, there was statistically higher blood loss with double IV (328 mL, 95% CI = 323-333 mL) TXA than in the combined group (295 mL, 95% CI = 280-310 mL) (P < .001). The rate of transfusion was statistically similar at ~2% (P = .970).ConclusionsA double IV TXA dose and a combined single IV and topical TXA dose were equally effective in minimizing blood transfusions (~2%) at primary TKA and THA. We did not find a synergistic effect when combining a systemic IV TXA with a topical TXA.Level of EvidenceLevel III.

Improved Compartment Balancing Using a Robot-Assisted Total Knee Arthroplasty.

BackgroundRobot-assisted surgery was developed to improve accuracy and outcomes in total knee arthroplasty (TKA). One important determinant of TKA success is a well-balanced knee throughout the range of motion. The purpose of this study is to determine if robot-assisted TKA (RA-TKA) results in improved intracompartmental ligament balance compared with conventional jig-based instrumentation (CM-TKA).MethodsThis retrospective cohort study included 2 cohorts—a CM-TKA (n = 49) vs RA-TKA (n = 37) cohort. Demographic and intraoperative data, including intraoperative compartment loads, were measured after final implant implantation in extension (10°), mid-flexion (45°), and full flexion (90°), using an intraoperative compartment pressure sensor. An a priori power analysis revealed our study exhibited >80% power in detecting a 5-pound (lb) difference in compartment loads in the 2 cohorts.ResultsThere was no difference between medial and lateral compartment loads in extension, mid-flexion, and full flexion for the conventional (15.1 lbs, 15.9 lbs, and 13.4 lbs, respectively) vs RA-TKA (14.2 lbs, 15.1 lbs, and 10.3 lbs, respectively). The percentage of patients with high load compartment pressure in flexion (>40 lbs) by the conclusion of the surgery was significantly greater for the conventional (18%) vs the robotic TKA cohort (3%, P = .025). The percentage of patients with unbalanced knees (>20 lbs differential between medial and lateral compartments) in flexion was significantly greater in the conventional (24%) vs robotic TKA cohort (5%, P = .018).ConclusionsIn this series, RA-TKA resulted in improved intraoperative compartment balancing in flexion with no observed difference in mid-flexion and extension compared with CM-TKA.

Change in Body Mass Index after Simultaneous Bilateral Total Knee Arthroplasty: Risk Factors and Its Influence on Functional Outcomes

BackgroundPrevious studies evaluating weight changes following total knee arthroplasty (TKA) were performed on heterogenous cohorts. However, no study has evaluated weight changes in a cohort of simultaneous-bilateral TKA (SB-TKA) patients. This study aimed to evaluate the prevalence of patients who lost or gained weight, determine if postoperative weight change influences functional outcome, and identify predictors of weight change after SB-TKA. MethodsProspectively collected registry data of 560 patients who underwent SB-TKA were reviewed. Patients were assessed preoperatively, at 6 months, and 2 years using the Knee Society Score, Oxford Knee Score, Short-Form 36, and range of motion. Change in body mass index (BMI) >5% was used to categorize patients into 3 groups: lost, maintained, or gained weight. Analysis of variance, Kruskal-Wallis test, and chi-squared test were used to compare functional outcomes between groups. Multivariable logistic regression evaluated predictors for postoperative weight changes. ResultsAt 2 years, 59% of patients maintained weight, 28% of patients gained weight, and 13% of patients lost weight. All groups experienced similar improvements in functional outcomes, rates of minimal clinically important difference attainment, and patient satisfaction (P > .05). Older patients were more likely to gain weight (P < .05). Patients with higher preoperative BMI were more likely to gain weight (P < .05) and less likely to lose weight (P < .05). Patients with greater preoperative comorbidities were less likely to lose weight (P < .05). ConclusionUp to 41% of patients experience significant weight changes after SB-TKA. Older patients with higher preoperative BMI were more likely to gain weight, while higher preoperative BMI with more comorbidities were less likely to lose weight following SB-TKA; however, postoperative weight changes do not appear to affect functional outcomes. Level of EvidenceIII, therapeutic study.

Incidence and Causes of Tibial Component Loosening Based on Level of Obesity in a Large Consecutive Cohort of Cemented Primary TKAs without Stem Extensions

Background and Hypothesis: Aseptic loosening is one of the most common failure mechanisms of total knee arthroplasty (TKA) requiring revision. The influence of obesity on tibial component aseptic loosening remains unknown. Some surgeons advocate the addition of a tibial stem extension to reduce the risk of loosening. The purpose of this study was to quantify the incidence and causes of revision for tibial component loosening in a large consecutive cohort of cemented primary TKAs without stem extensions based upon level of obesity. &#x0D; &#x0D; Experimental Design or Project Methods: 534 consecutive cemented primary TKAs performed between 2016 and 2018 by one surgeon were retrospectively reviewed. Procedures were performed using consistent surgical, perioperative medical, and pain-control protocols. All tibial implants were tapered thin keeled designs without stem extensions and implanted with low viscosity cement. Medical records were examined and all-cause revisions of the index surgery were documented. &#x0D; &#x0D; Results: After exclusions for confounds, 525 TKAs were analyzed. Mean age and BMI were 67.8 years and 33.9kg/m2 respectively and 72% were female. Mean follow-up was 19.1 (SD 10.5) months and 48% had minimum two-year follow-up. 41.3% of patients had a BMI greater than 35kg/m2 and 21.9% above 40kg/m2. There were 11 revisions in 10 patients, 1.9% out of all TKAs performed. Five TKAs required both-component revision and three involved the femoral component only. No tibial component revisions were performed for aseptic loosening. &#x0D; &#x0D; Conclusion and Potential Impact: None of the standard tibial implants with a keeled design without stem extensions failed in a patient population with greater than 40% obesity. Despite some suggesting tibial stem extensions should be used in obese TKA patients, these findings suggest that tibial component failure in obese patients may be design specific and routinely utilizing stem extensions may not be warranted and could result in deleterious bone loss at revision if required for reasons other than aseptic loosening.

Robotic Total Knee Arthroplasty vs Conventional Total Knee Arthroplasty: A Nationwide Database Study.

BackgroundAs robot-assisted equipment is continuously being used in orthopaedic surgery, the past few decades have seen an increase in the usage of robotics for total knee arthroplasty (TKA). Thus, the purpose of the present study is to investigate the differences between robotic TKA and nonrobotic TKA on perioperative and postoperative complications and opioid consumption.MethodsAn administrative database was queried from 2010 to Q2 of 2017 for primary TKAs performed via robot-assisted surgery vs non–robot-assisted surgery. Systemic and joint complications and average morphine milligram equivalents were collected and compared with statistical analysis.ResultsPatients in the nonrobotic TKA cohort had higher levels of prosthetic revision at 1-year after discharge (P < .05) and higher levels of manipulation under anesthesia at 90 days and 1-year after discharge (P < .05). Furthermore, those in the nonrobotic TKA cohort had increased occurrences of deep vein thrombosis, altered mental status, pulmonary embolism, anemia, acute renal failure, cerebrovascular event, pneumonia, respiratory failure, and urinary tract infection during the inpatient hospital stay (all P < .05) and at 90 days after discharge (all P < .05). All of these categories remained statistically increased at the 90-days postdischarge date, except pneumonia and stroke. Patients in the nonrobotic TKA cohort had higher levels of average morphine milligram equivalents consumption at all time periods measured (P < .001).ConclusionsIn the present study, the use of robotics for TKA found lower revision rates, lower incidences of manipulation under anesthesia, decreased occurrence of systemic complications, and lower opiate consumption for postoperative pain management. Future studies should look to further examine the long-term outcomes for patients undergoing robot-assisted TKA.Level of EvidenceLevel III.

Perioperative steroid administration improves knee function and reduces opioid consumption in bilateral total knee arthroplasty

IntroductionThe benefits of steroid usage have been well described for unilateral total knee arthroplasty (TKA), however it's benefits in bilateral TKA has not been well published in the literature. We describe the impact of perioperative steroid administration in a cohort of bilateral TKAs (74 knees) with regard to immediate postoperative knee function, postoperative knee strength and opioid consumption. Materials and methodsWe report on a single-surgeon consecutive case series of simultaneously-performed bilateral TKAs. Eighteen patients received 2 doses of 8 mg IV dexamethasone in the perioperative setting. There were 19 patients in the control group. Primary outcome measures were day 1 postoperative knee flexion (degrees), knee strength and postoperative analgesic requirements (mg/mcg). Morphine dose equivalents (MDE) were calculated to compare all opioid-based analgesics. Secondary outcomes included post-operative pain according to the VAS (at 24, 48 and 72 h), anti-emetic requirements (mg) and length of stay (days). ResultsThe mean knee flexion achieved day 1 in the steroid group was 70.1°(σ = 17.64, 95% CI 64.1–76.0) compared to 55.8° in the non-steroid group (σ = 19.8, 95% CI 49.2–62.3) (p = 0.0008). Regarding the straight leg raise, 88.9% of the steroid group were able to achieve this compared to only 55.2% of the non-steroid group (p = 0.002). There was a reduction in the MDE requirement per patient across all medications for the ‘steroid’ group. Both Targin® (p = 0.03) (Prolonged-Release Oxycodone) and Fentanyl (p = 0.01) requirements were significantly reduced in the ‘steroid’ group. ConclusionWe recommend the use of perioperative steroids in bilateral TKA to allow accelerated rehabilitation, improved immediate knee function and an overall reduction in the consumption of potentially problematic opioid-based analgesics.

Posterior Cruciate Ligament Resection Does Not Consistently Increase the Flexion Space in Contemporary Total Knee Arthroplasty

IntroductionIt is accepted dogma in total knee arthroplasty (TKA) that resecting the posterior cruciate ligament (PCL) increases the flexion-space by approximately 4mm. Unfortunately, this doctrine is based on historical studies of limited size with variable technique. The aim of this study was to determine the effect of PCL-resection on in vivo tibiofemoral joint space dimensions in a cohort of modern TKAs. MethodsTibiofemoral joint space measurements were made during 129 standardized TKAs by two arthroplasty surgeons. A medial parapatellar approach, computer navigation and provisional bone cuts were performed in all cases with particular attention to preserving PCL integrity. The tibiofemoral gap was measured with a calibrated tension device at extension, 45-degrees, and 90-degrees before and after complete PCL-resection. Results51% of patients were female (66/129) with mean age and BMI of 69.5 years and 34.2 kg/m2, respectively. After PCL-resection, mean change in center joint space dimension increased 0.33mm at extension, 0.95mm at 45-degrees, and 1.71mm at 90-degrees (P < .001). The 90-degree flexion-space opened ≥4mm in only 10% of patients. Dividing the flexion-space change by femoral implant dimension to account for patient size, the flexion-space at 90-degrees significantly increased more in females compared to males (P = .020). ConclusionThe tibiofemoral joint space increased progressively from extension to mid-flexion through deep-flexion after PCL-resection, yet was substantially less than reported in historical studies. However, large variation in flexion-space opening was observed with some patients failing to increase the flexion-space whatsoever with PCL-resection. This runs counter to conventional TKA understanding and should be considered in modern surgical education. Level of EvidenceTherapeutic Level III.