A smartphone-based care platform allows a customizable educational and exercise interface with patients, allowing many to recover after surgery without the need for formal physical therapy (PT). Furthermore, advances in wearable technology to monitor physical activity (PA) provides patients and physicians quantifiable metrics of the patient's recovery. The purpose of this study is to determine the feasibility of a smartphone-based exercise educational platform after primary knee arthroplasty as well as identifying factors that may predict the need for formal physical therapy. This study is part of a multi-institution, prospective study of patients after primary total knee arthroplasty (TKA) and partial knee arthroplasty (PKA) enrolled in a smartphone with smartwatch-based episode of care platform that recorded multimodal PA (steps, kcal, stairs). Postoperatively, all patients initially followed the smartphone-based exercise program. At the surgeon's discretion, patients were prescribed therapy if needed. The outcome of this study was the need for PT outside the app-based exercise program as well as time to return to preoperative step count. Variables assessed were preoperative weekly step counts (steps/day), weekly postoperative activity level (weekly step count compared to preoperative level), compliance with the exercise program (>75% completion) and patient demographic data including gender, age, BMI and narcotic use. One hundred eighty-eight patients were included in analysis: 45 PKA (24%) and 143 TKA (76%). Step count data was available on 135 patients and physical therapy data on 174.Introduction
Methods
Maintaining posterior stability in total knee arthroplasty (TKA) may be achieved by using a posterior stabilized TKA, retaining and balancing the posterior cruciate ligament (PCL) using a traditional cruciate-retaining design (CR), or by increasing the sagittal plane conformity of the tibial insert. In the latter case, stability is achieved by the addition of an anterior buildup on the tibial polyethylene creating the so-called “anterior stabilized” (AS) design. We hypothesized that using an AS tibial insert would provide similar function and survivorship as compared to using a more traditional CR bearing when the PCL is either recessed or balanced. Between 2004 and 2016, 1,731 modular CR TKAs were implanted in 1,509 patients using the same CR TKA design. The diagnosis was osteoarthritis in 98%. 58% of patients were female. Average age of 64.9 years. Within this group, 868 TKAs (50.1%) had a standard CR tibial bearing (3-degree posterior slope and no posterior lip) implanted (CR-S). 480 TKAs (27.8%) had a lipped CR modular tibial bearing (2.5 mm elevated posterior lip) implanted (CR-L). Starting in 2013, 383 TKAs (22.1%) were implanted with an AS modular tibial bearing (9–11 mm anterior lip and a 5 mm posterior lip). If the PCL was considered non-functional or absent, an AS bearing was placed. If the PCL was considered functional, a standard bearing or lipped bearing was used. Clinical and radiographic analysis was performed according to the Knee Society (KS) grading system. The most recent clinical and radiographic evaluation was used for post-operative analysis. The average follow-up in the entire cohort of TKAs was 5.5 years (range 2 to 14.3 years). Kaplan-Meier analysis was used to determine prosthesis survivorship with failure defined as aseptic loosening of the prosthesis (with or without revision) or tibial insert exchange.Introduction
Methods
Metaphyseal cones with cemented stems are frequently used in revision total knee arthroplasties (TKAs). However, if the diaphysis has been previously violated (as in revision of a failed stemmed implant), the resultant sclerotic canal can impair cemented stem fixation, which is vital for cone ingrowth and long-term fixation. We report the outcomes of our novel solution to this problem, in which impaction grafting and a cemented stem in the diaphysis was combined with an uncemented metaphyseal cone for revision TKAs with severely compromised bone. A metaphyseal cone was combined with diaphyseal impaction grafting and cemented stems in a novel fashion for 35 revision TKAs. Mean age at revision TKA was 70 years, with 63% being male. Patients had a mean of 4 prior knee arthroplasty procedures. Indications for the revision with this construct were aseptic loosening (80%) and two-stage re-implantation for periprosthetic infection (PJI; 20%). Mean follow-up was 3 years.Introduction
Methods
In 2015, the healthcare system transitioned from International Classification of Diseases, Ninth Revision (ICD-9) coding to the Tenth Revision (ICD-10). Given that administrative claims are used for quality initiatives, risk adjustment models and clinical research, we sought to determine the effect of new, more detailed coding on the incidence of complications following primary total knee arthroplasty (TKA). The Humana administrative claims database was queried from 2-years prior to October 1, 2015 (ICD-9 cohort) and for 1-year after this date (ICD-10 cohort) to identify all primary TKA procedures. Each TKA was then tracked for occurrence of an arthroplasty specific post-operative complication within 6 months of surgery using the respective coding systems. Laterality and joint specific codes were utilized for the ICD-10 cohort to ensure complications occurred on the same side and joint as the index procedure. Incidence of each complication was compared between cohorts using risk ratios (RR) and 95% confidence intervals.Introduction
Methods
Emergency department (ED) visits following primary total knee arthroplasty (TKA) can lead to poor patient satisfaction, potentially unnecessary readmissions, and greater overall healthcare costs. Reasons for post-operative ED visits are often entirely medical in nature and can be independent of the recent operation. Several strategies have been developed to help reduce ED visits. However, one major factor that can play a critical role in addressing potentially avoidable visits is provider and patient education. A major factor that can play a crucial role in addressing potentially avoidable visits is provider and patient education. It follows that a thorough understanding of which patients are visiting the ED and why can help in avoiding the visits. Therefore, the purpose of this study was to investigate: 1) causes and 2) patient-related factors (demographics and comorbidities) associated with ED visits following primary TKA. A national private payer database was queried for primary TKAs performed between 2007 and 2016 using the International Classification of Disease, ninth revision (ICD-9) procedural code 81.54. ED visits were identified using Current Procedural Terminology (CPT) codes 99281 to 99285. Patients with 90-day ED visits were in the study group (n=28,044) whereas those without 90-day ED visits served as controls (n=82,289). Causes for ED visits were divided into cardiopulmonary, gastrointestinal, renal, thromboembolic, leg pain, or wound-related. Patient demographics and risk factors assessed included age, gender, and body mass index (BMI) as well as several comorbidities (Table 1). Pearson's chi-square tests were performed to compare patient demographics and comorbidities between the cohorts. In order to adjust for potential confounders, multivariate binomial logistic regression analysis was performed to further evaluate the associations between patient factors and 90-day ED visits. A p-value less than 0.01 was considered statistically significant.Introduction
Methods
Insufficient pain control following lower extremity surgery can increase length of stay, readmission rates, and impair postoperative outcome. It has been shown that CYP2D6 genotypes predict function of the enzyme responsible for conversion of hydrocodone to hydromorphone (active metabolite) and plasma concentration of hydromorphone best predicted analgesic response. Purpose of this study was to evaluate relationship of CYP2D6 genotypes, drug-drug interactions, and plasma drug concentrations in patients undergoing lower extremity surgery. A prospective cohort of 271 orthopedic patients undergoing lower extremity surgery including TKA, THA and trauma were queried. Patients treated with hydrocodone were enrolled and tested for plasma concentrations of hydrocodone and hydromorphone. CYP2D6 genotyping was performed. Medications co-administered with hydrocodone during perioperative and postoperative periods were queried.Introduction
Methods
One of the more common complaints from patients in their post-operative total knee arthroplasty (TKA) is the perceived feeling of the operative leg feeling longer than the non-operative leg. Studies have shown that the leg length discrepancies may occur in up to 80% of patients following unilateral TKA patients. The purpose of this study was to determine the incidence of leg length discrepancy (LLD) after primary TKA as well as determine the correlation between deformity and incidence of LLD. We retrospectively reviewed 1108 patients who underwent a primary unilateral TKA at a single institution. 97 patients were excluded for lack of imaging, prior total hip replacement or body mass index greater than 40 kg/m2. Hip to ankle biplanar radiographs were obtained pre-operative and 6 weeks postoperatively for all patients. Two independent observers measures leg length, femur length, tibia length, overall alignment and deformity present for all radiographs.Introduction
Methods
Our purpose is to analyze the true costs associated with preoperative CT scans performed for robotic assisted TKA planning and also to determine the value of a formal radiologist reading of these studies. We reviewed 194 CT scans of 176 sequential patients who underwent primary RTKA by a single surgeon at a suburban teaching hospital. CT radiology reports were reviewed for the presence of incidental findings that might result in change of care to the patient. Actual payments for technical and professional components of the CT scans were retrieved for 170 of the 176 patients. Any patient payments for the CT scan were also recorded.Introduction
Methods
Obesity has been shown to be an independent risk factor for aseptic loosening of the tibia and smaller implant size has been correlated with increased risk of failure of tibial components in obese patients [1,2]. Many surgeons have noted that obese patients, especially females, not uncommonly will have small implant sizes. As such, we hypothesized that obesity was not directly correlated with total knee arthroplasty (TKA) implant sizes. The purpose of this study was to determine if increasing body mass index (BMI), height, and/or weight is associated with implant size in primary TKA. The institutional registry of a single academic center was reviewed to identify all primary TKAs performed between 2005 and 2016. Those without minimum 2-year follow-up or with incomplete implant data were excluded. The different manufacturer's implant designs were categorized based on anteroposterior and mediolateral dimensions of the femoral and tibial component sizes and cross sectional area was determined. BMI was categorized by the World Health Organization (WHO) obesity scale (Class I: BMI 30 to <35, Class II: BMI 35 to <40, Class III: BMI 40 kg/m2 or greater). Patient demographics including sex, height, weight, and BMI were analyzed to evaluate correlations with implant size using Pearson correlation coefficients.Background
Methods
Robotic-assisted total knee arthroplasty (TKA) was introduced to improve limb alignment, component positioning, and soft-tissue balance, yet the effect of adoption of this technology has not been established. This study was designed to evaluate whether robotic-assisted TKA leads to improved patient reported outcome measures (PROMs) and patient satisfaction as compared to conventional TKA at 3 and 12 months. This IRB-approved single-surgeon retrospective cohort analysis of prospectively collected data compared 113 conventional TKA patients with 145 imageless robotic-assisted TKA patients (Navio™ Surgical System, Smith&Nephew®, Memphis TN). Basic demographic information, intraoperative and postoperative data, and PROMs (SF-P, SF-M, WOMAC pain, WOMAC stiffness, WOMAC Physical Function, KSS) were collected and recorded preoperatively, at 3 months, and at 12 months following surgery. Range of motion (ROM), blood loss, surgical duration, and complication rates between groups were also collected. Continuous measures such as mean difference in PROMs and ROM were compared using unpaired t-tests. Categorical measures such as the percentage of patients with complications were compared using chi-square analysis.Introduction
Methods
Total knee arthroplasty (TKA) reliably improves pain and function in patients with knee osteoarthritis (OA), though a substantial percentage of patients remain unsatisfied. Reasons include the presence of complications, persistent pain, and unmet expectations. The aim of this study was to determine whether the sequential addition of accelerometer-based navigation of the distal femoral cut and sensor-assisted soft tissue balancing changed complication rates, radiographic alignment, or patient-reported outcomes (PROs) compared to TKA performed with conventional instrumentation. This retrospective cohort study included 371 TKAs in 319 patients. All surgeries were performed by a single surgeon in sequential fashion using a measured resection technique with a goal of mechanical alignment. The historical control group, utilizing intramedullary guides for distal femoral resection and surgeon-guided soft tissue balancing, was compared to group 1 (accelerometer-based navigation for distal femoral resection, surgeon-guided balancing) and group 2 (navigated femoral resection, sensor-guided balancing). Primary outcome measures were PROMIS scores including physical function computerized adaptive test (PF CAT), and the Global 10 health assessment (including physical, mental, and pain scores), and Knee Injury Osteoarthritis and Outcome Score (KOOS), measured preoperatively and at 6 weeks and 12 months postoperatively. Radiographic measurements included component position and overall mechanical alignment of the limb and were made at 6 weeks by a single examiner from hip to ankle standing films. Charts were reviewed for pre- and postoperative ROM at 6 weeks, polyethylene insert morphology, and postoperative hematocrit change. Complications were recorded, including manipulation under anesthesia and reoperation. Our study was powered to detect a difference of 1 standard deviation in PF CAT score with 100 patients. Statistical analysis was performed by a statistician including t-tests, multivariate regression, and time series plot analyses.Introduction
Methods
The purpose of this multi-center, randomized clinical trial was to compare static and articulating spacers in the treatment of PJI complicating total knee arthroplasty TKA. 68 Patients treated with two-stage exchange arthroplasty were randomized to either a static (32 patients) or an articulating (36 patients) spacer. A power analysis determined that 28 patients per group were necessary to detect a 13º difference in range of motion between groups. Six patients were excluded after randomization, six died, and seven were lost to follow-up prior to two years.Background
Methods
In November 2017, the Center for Medicare and Medicaid Services (CMS) finalized the 2018 Medicare Outpatient Prospective Payment System rule that removed total knee arthroplasty (TKA) procedures from the Medicare inpatient-only (IPO) list of procedures. This action had significant and unexpected consequences. For several years, CMS has utilized a rule called the “Two-Midnight Rule” to define outpatient status for all procedures not on the IPO list. CMS made TKA subject to the “Two-Midnight Rule” in conjunction with the decision to move TKA off the IPO list. According to the “Two-Midnight Rule,” a hospital admission should be expected to span at least two midnights in order to be covered as an inpatient procedure. If it can be reliably expected that the patient will not require at least two midnights in the hospital, the “Two-Midnight Rule” suggests that the patient is considered an outpatient and is therefore subject to outpatient payment policies. Under prior guidance related to the “Two-Midnight Rule;” however, CMS also states that Medicare We looked at 3 different levels of the IPO rule impact on TKA for Medicare beneficiaries: a national comparison of fee for service (FFS) inpatient and outpatient classification for 2017 vs 2018; a survey of AAHKS surgeons completed in April of 2019; and an in-depth analysis of a large academic medical center experience. An analysis of change in inpatient classification of TKA patients over time, number of Quality Improvement Organization (QIO) audits, compliance solutions of organizations for the new rule and cost implications of those compliance solutions were evaluated.Introduction
Methods
Bundled reimbursement models for total knee arthroplasty (TKA) by the Center for Medicare and Medicaid Services (CMS) have resulted in an effort to decrease the cost of care. However, these models may incentivize bias in patient selection to avoid excess cost of care. We sought to determine the impact of the Comprehensive Care for Joint Replacement (CJR) model at a single center. This is a retrospective review of primary TKA patients from July 2015-December 2017. Patients were stratified by whether or not their surgery was performed before or after implementation of the CJR bundle. Patient demographic data including age, sex, and BMI were collected in addition to Elixhauser comorbidities and ASA score. In-hospital outcomes were then examined including surgery duration, length of stay, discharge disposition, and direct cost of care.Introduction
Methods
The purpose of bundled payment programs is to reduce cost via risk sharing, while still maintaining quality. If savings are achieved under a historic target price, the orthopedic surgeon will receive a monetary bonus. If costs are higher, a portion is deducted from payment to the orthopedic surgeon. The purpose of this study was to evaluate our experience with the Bundled Payments for Care Improvement Program (BPCI) when run by an orthopedic surgeon group to determine patient safety and who benefited the most financially. This program ran from January 2015 through September 2018. 3,186 Medicare total hip and knee replacements, elective (DRG 470) and for fracture (DRG 469), performed by our group were included. 90 day hospital and all postoperative expenditures were reconciled against our historic cost. All patients were medically optimized with discharge plans established preoperatively. We developed preferred skilled nursing facilities and home health care agencies with synergistic medical providers so that discharges were recommended as soon as appropriate. We hired two full-time case managers to have direct contact with patients pre-and post-operatively. Waiver assistance such as house and pet sitters were used if necessary at our expense. 35% of savings went to the convener, who acted as a liaison between our group and CMS. Expenditures for the 90-day period for all patients were calculated to determine where savings occurred and which entity benefitted financially.Introduction
Methods
Inability to reproduce 6-degrees of freedom (6DOF) kinematics, abnormal “paradoxical” anterior femoral translation and loss of normal medial pivot rotation are challenges associated with contemporary posterior cruciate retaining and posterior stabilized total knee arthroplasty (TKA). The removal of the anterior and/or both cruciate ligaments in CR/PS TKA, leading to significant kinematic alteration of the knee joint, has been suggested as one of the potential contributory factors in patients remaining dissatisfied after TKA. Bi-cruciate retaining (BCR) TKA designs allow preservation of both anterior and posterior cruciate ligaments with the potential to replicate normal knee joint kinematics. Physically demanding tasks such as sit-to-stand (STS), and deep lunging may be more sensitive tools for investigating preserved kinematic abnormalities following TKA. This study aims to compare in-vivo kinematics between the operated and the contralateral non-operated knee in patients with contemporary BCR TKA design. Twenty-nine patients (14 male; 15 female, 65.7±7.7 years) unilaterally implanted with a contemporary BCR TKA design featuring an asymmetric femoral component and independently designed medial and lateral bearings were evaluated. Mean follow-up time after BCR TKA was 12.7±5.1 months. All patients received a computer tomography (CT) scan from the pelvis to the ankles for the creation of 3D surface models of both knees (BCR TKA and non-operated). Patients performed single leg deep lunges and sit-to-stand under a validated dual fluoroscopic imaging system (DFIS) surveillance. Each patient's 2D dynamic fluoroscopic images, corresponding 3D surface bone models (for contralateral non-operated knee) and computer aided design (CAD) implant models (for the BCR TKA implanted knee) were imported into a virtual DFIS environment in MATLAB. An optimization procedure was utilized to perform matching between the 3D surface bone models and the 2D fluoroscopic image outlines. In-vivo 6DOF kinematics of the BCR TKA knees and contralateral non-operated side were quantified and analyzed.Introduction
Methods
Pharmacogenetics evaluates a patient's DNA to determine if a particular drug is expected to have a normal clinical effect, heightened effect, or no effect at all on a patient. It may also predict which patients are most likely to experience side effects from the medications. The purpose of this study was to use pharmacogenetic testing to determine how frequently total knee arthroplasty (TKA) patients have genetic variants to standard postoperative pain medications. We further sought to determine if changing the multimodal program based on these results would improve pain control and reduce side effects. In this prospective, randomized study, buccal cheek swab samples were collected from 31 primary TKA patients. Pharmacogenetics testing was performed on the samples to examine genetic variants in genes OPRM1, CYP1A2, CYP2B6, CYP2C19, CYP3A4, CYP2C9, and CYP2D6. These genes affect the pharmacodynamics and pharmacokinetics of NSAIDs and opioids. We examined the frequency of a genetic variant to one of the multimodal medications we prescribe including celecoxib, hydrocodone, and tramadol. Subjects included 9 men and 22 women. Patients were randomized to one of two groups: the control group received the standard postoperative pain regimen; the study group received a customized regimen based on the pharmacogenetic results. For the first 10 postoperative days patients recorded pain scores, amount of pain medication taken, and any side effects experienced.Introduction
Methods
Vancomycin is a prophylactic antibiotic used to protect against methicillin resistant staph aureus. Recent literature has suggested that using intraosseus (IO) infusions are capable of providing improved local tissue concentrations compared to intravenous (IV) access. The purpose of this study is to evaluate clinical outcomes of patients who received pre-operative IO vancomycin for total knee arthroplasty (TKA). Patients who received IO vancomycin (500mg vancomycin in 200ml NS) as standard of care from September 1, 2018 to March 1, 2019 were retrospectively evaluated. This data was compared to primary and revision TKAs performed immediately prior to the initiation of IO administration. Evaluation included pre and post-op creatinine values, tourniquet time (TT), and knee-related 30 and 90-day complications. Data for primary and revision TKA cases were analyzed independently.Introduction
Methods
The aims of this prospective study were to determine the effect of osteophyte excision on deformity correction and soft-tissue gap balance in varus knees undergoing computer-assisted total knee arthroplasty (TKA). Four-hundred twenty-five consecutive, cemented, cruciate-substituting TKAs were analysed. Pre-operative varus was calculated on long leg weight-bearing HKA film. Limb deformity in coronal (varus) and sagittal (flexion) planes, medial and lateral gap distances in maximum knee extension and 90° knee flexion and maximum knee flexion were recorded before and after excision of medial femoral and tibial osteophytes using computer navigation. Data was extracted and analysed to assess the effect of removal of osteophytes on the correction of deformity and soft tissue balance.Aims
Patients and Methods
The purpose of this study was to evaluate the clinical and radiographic outcomes of the rotating-platform, posterior-stabilized PFC Sigma at fifteen-year follow-up. Between January 2000 and November 2001, two hundred consecutive patients underwent TKA with a rotating-platform, posterior stabilized total knee arthroplasty with cement. All patients have been followed prospectively and all patients with minimum 12 year follow up were included in this analysis. Forty-nine TKAs were available for our final analysis with a mean follow up of 16.0 years.Background
Methods
The commonest causes of revision of Unicompartmental Knee Replacement (UKR) in National Registers are loosening and pain. Cementless UKR was introduced to address loosening and was found, in small randomised studies, to have better radiographic fixation than Cemented UKR. Although non-significant these studies also suggested the clinical outcome was better with cementless. The aim of this larger study was to compare the pain and function of cementless and cemented UKR at five years. 263 Cemented and 266 Cementless UKR of identical design, implanted by four high volume surgeons for the same indications, were reviewed by independent physiotherapists at five years. Revision, re-operation, Oxford Knee Score (OKS), American Knee Society score (AKSS) and EQ-5D were assessed. Two pain specific scores were also used: Pain Detect (PD) and Intermittent and Constant Osteoarthritis Pain (ICOAP). The pain scores were normalised onto a scale of 0 to 100 with 100 being the best. The cemented cohort was mainly implanted before the cementless, although there was considerable overlap. To explore whether differences were due to progressive improvement in surgical practice with time each cohort was divided into early and late subgroups.Introduction
Methods
The number of medial unicompartmental knee replacements (UKR) performed for arthritis has increased and as such, revisions to total knee replacement (TKR) is increasing. Previous studies have investigated survivorship of UKR to TKR revision and functional outcomes compared to TKR to TKR revision, but have failed to detail the surgical considerations involved in these revisions. Our objectives are to investigate the detailed surgical considerations involved in UKR to TKR revisions. This study is a retrospective comparative analysis of a prospectively collected database. From 2005 to 2017, 61 revisions of UKR to TKR were completed at a single center. Our inclusion criteria included: revision of UKR to TKR or TKR to TKR with minimum 1 year follow-up. Our exclusion criteria include: single component and liner revisions and revision for infection. The 61 UKR to TKR revisions were matched 2:1 with respect to age, ASA and BMI to a group of 122 TKR to TKR revisions. The following data was collected: indication for and time to revision, operative skin to skin surgical time, the use of specialized equipment (augment size/location, stem use), intraoperative and postoperative complications, re-operations and outcome scores (WOMAC, Oxford 12, SF 12, satisfaction score).Introduction
Methods
Robotic technology has been applied to unicompartmental knee arthroplasty (UKA) in order to improve surgical precision in prosthetic component placement, restore knee anatomic surfaces, and provide a more physiologic ligament tensioning throughout the knee range of motion. Recent literature has demonstrated high reliability of robotic-arm assisted UKA in component placement and executing a soft-tissue tensioning plan, with excellent short-term survivorship. Few studies have investigated survivorship and patients' satisfaction at longer follow-ups. Therefore, the purpose of the present study was to determine the survivorship, clinical results and patients' satisfaction of robotic-arm assisted UKAs at a mid-term follow-up, with a minimum of 5 years of follow-up. The present retrospective study includes 252 patients (260 knees) who underwent robotic-arm assisted fixed bearing metal backed UKAs at a single centre between April 2011 and July 2013. The mean age at surgery was 66.2 years (SD 8.6). Post-operatively, patients were administered the Forgotten Joint Score-12 (FJS) and asked about their satisfaction level after knee surgery (grade from 1 to 5). Post-operative complications were recorded. Failure mechanisms, revisions and reoperations were also assessed. Kaplan-Meier survival curves were calculated, considering reoperation for all causes and revision as the events of interest.Introduction
Methods
Active robotics for total knee Arthroplasty (TKA) uses a CAD-CAM approach to plan the correct size and placement of implants and to surgically achieve planned limb alignment. The TSolution One Total Knee Application (THINK Surgical Inc., Fremont, CA) is an open-implant platform, CT-based active robotic surgical system. A multi-center, prospective, non-randomized clinical trial was performed to evaluate the safety and effectiveness of robotic-assisted TKA using the TSolution One Total Knee Application. This report details the findings from the IDE. Inclusion criteria for patients receiving robotic TKA were: primary unilateral TKA; Kellgren-Lawrence OA grade 3 or 4; BMI < 40 kg/m2; coronal plane deformity < 20° varus; sagittal flexion contracture < 15°. In addition to monitoring all adverse events (AE), a pre-defined list of relevant major AEs were specifically identified to evaluate safety (Healy et al, 2013): medial collateral ligament injury; extensor mechanism disruption; neural deficit; periprosthetic fracture; patellofemoral dislocation; tibiofemoral dislocation; and vascular injury. Bleeding complications were also assessed. Malalignment rate, defined as the percentage of patients with more than a ± 3° difference in varus-valgus alignment from the preoperative plan, was used to determine accuracy of the active robotic system. Knee Society Scores (KSS) and Short Form 12 (SF-12) Health Surveys were assessed as clinical outcome measures. For each outcome, results were compared to published values associated with manual TKA.Introduction
Methods
Previous studies on Medicare populations have shown improved outcomes and decreased 90-day episode-of-care costs with robotic assisted total knee arthroplasty (rTKA). The purpose of this study was to evaluate the expenditures and utilization following rTKA in the under 65 y/o population. TKA procedures were identified using the OptumInsights Inc. database. A two-year window was studied. The procedures were stratified in two groups: the rTKA or manual (mTKA) cohorts. Propensity score matching (PSM) was performed at 1:5. Utilization and associated costs were analyzed for 90 days following the index procedure. 357 rTKA and 1785 mTKA were included in this analysis.Introduction
Methods
Patients who undergo total joint arthroplasty (TJA) are at a high risk for the development of thromboembolic complications. The rate at which venous thromboembolism occurs following TJA has been reported to be between 1.3–9.4%. As a result, the utilization of prophylactic therapies is considered standard of care in this patient population. The primary purpose of the current study was to 1) evaluate patient satisfaction with the use of intermittent compression devices 2) evaluate the risk of self-reported falls secondary to the use of these devices following TJA. This is a single institution, prospective study on patients who underwent TJA at an urban, academic orthopedic specialty hospital. Patients were surveyed using an electronic patient rehabilitation application regarding their use and satisfaction with their home intermittent compression devices with a battery and power cord attachment that the patient must wear while using the devices. They were also asked if any falls or near-falls they may have experienced. Surveys were administered on postoperative Day 14, and patients were given 10 days to submit their responses. Using our institutions data warehouse, patient demographics were also collected (Table 1).Introduction
Methods
Studies of retrieved total knee replacement (TKR) components demonstrate that Eleven retrieved ultra-high molecular weight polyethylene (UHMWPE) cruciate-retaining tibial liner components from ten separate patients (implantation time = 8.6±5.6 years) had matching gait trials of normal level walking for each knee. Volume loss on retrieved components was calculated using a coordinate measuring machine and autonomous reconstruction.3 Motion analysis of normal level walking gait had been conducted between 1986 and 2005 for various previous studies and stored in a consented Human Mechanics Repository, ranging from pre-operative to long-term post-operative testing. Contact location between the femoral component and the tibial component on the medial and lateral plateaus were calculated throughout stance.4 A previously validated and fine-tuned parametric numerical model was used to calculate TKR contact forces for each gait trial.5 Vertical contact forces and contact paths on the medial and lateral plateaus were input as normal force and sliding distance to a simplified Archard equation for wear with material wear constant = 2.42 × 10−7 mm3/Nm2,6 to compute average wear per gait cycle. Wear rates were calculated using linear regression, and Pearson correlation examined correlations between modeled and measured wear.Introduction
Methods
The relationship between sagittal component alignment on clinical outcomes has not fully evaluated after TKA. This study evaluated the effect of sagittal alignment of the components on patient function and satisfaction as well as kinematics and kinetics. This study included 148 primary TKAs with cruciate-substituting prosthesis for primary OA. With post-operative lateral radiograph, femoral component flexion angle (γ) and tibial component posterior slope angle (90-σ) was measured. The patients was classified into multiple groups by every three degrees. Patient satisfaction in 2011KSS among groups were analyzed using one-way analysis of variance. By representing the component position which showed poor clinical outcomes, computer simulation analysis was performed, in which kinematics and kinetics in squatting activity were investigated.Introduction
Methods
The purpose of this study was to use patient generated digital surveillance PROM's to track outcomes of TKA, Medial PKA, Lateral PKA. From Aug 2018 until June 2019 we performed 873 knee arthroplasties. Of these, 41 were fixed bearing lateral partial knee replacements (5%), 309 medial partial knee replacements (35%), and 523 total knee replacements (60%). The average age was 65 years old and 59% were female. KOOS-Jr scores were recorded preoperatively, and 6, 12 months postoperatively using digital surveillance technology with a greater than 90% response rate.Introduction
Methods
The objective of this study was to assess the effect of PCL resection on flexion-extension gaps, mediolateral soft tissue laxity, fixed flexion deformity (FFD), and limb alignment during posterior-stabilised total knee arthroplasty (TKA). This prospective study included 110 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted posterior-stabilised TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess gaps pre- and post-PCL resection in knee extension and 90 degrees knee flexion. This study included 54 males (49.1%) and 56 females (50.9%) with a mean age of 68 ± 6.2 years at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1 ± 4.4 degrees varus.Introduction
Methods
Unicompartmental knee replacement (UKR) offers advantages over total knee replacement but has higher revision rates particularly for aseptic loosening. Cementless UKR was introduced in an attempt to address this. We used National Joint Registry (NJR) data to compare the 10-year results of cemented and cementless mobile bearing UKR whilst matching for important patient, implant and surgical factors. We also explored the influence of caseload on outcome. We performed a retrospective observational study using NJR data on 30,814 cemented and 9,708 cementless mobile bearing UKR implanted between 2004 and 2016. Logistic regression was utilised to calculate propensity scores allowing for matching of cemented and cementless groups for various patient, implant and surgical confounders, including surgeon's caseload, using a one to one ratio. 14,814 UKRs (7407 cemented and 7407 cementless) were propensity score matched. Outcomes studied were revision, defined as removal, addition or exchange of a component, and reasons for revision. Implant survival was compared using Cox regression models and groups were stratified according to surgeon caseload.Introduction
Methods
Implant loosening is a common cause of a poor outcome and pain after total knee arthroplasty (TKA). Despite the increase in use of expensive techniques like arthrography, the detection of prosthetic loosening is often unclear pre-operatively, leading to diagnostic uncertainty and extensive workup. The objective of this study was to evaluate the ability of a machine learning (ML) algorithm to diagnose prosthetic loosening from pre-operative radiographs, and to observe what model inputs improve the performance of the model. 754 patients underwent a first-time revision of a total joint at our institution from 2012–2018. Pre-operative X-Rays (XR) were collected for each patient. AP and lateral X-Rays, in addition to demographic and comorbidity information, were collected for each patient. Each patient was determined to have either loose or fixed prosthetics based on a manual abstraction of the written findings in their operative report, which is considered the gold standard of diagnosing prosthetic loosening. We trained a series of deep convolution neural network (CNN) models to predict if a prosthesis was found to be loose in the operating room from the pre-operative XR. Each XR was pre-processed to segment the bone, implant, and bone-implant interface. A series of CNN models were built using existing, proven CNN architectures and weights optimized to our dataset. We then integrated our best performing model with historical patient data to create a final model and determine the incremental accuracy provided by additional layers of clinical information fed into the model. The models were evaluated by its accuracy, sensitivity and specificity.Background
Methods
Next generation sequencing (NGS) has been shown to facilitate detection of microbes in a clinical sample, particularly in the setting of culture-negative periprosthetic joint infection (PJI). However, it is unknown whether every microbial DNA signal detected by NGS is clinically relevant. This multi-institutional study was conceived to 1) identify species detected by NGS that may predict PJI, then 2) build a predictive model for PJI in a developmental cohort; and 3) validate the predictive utility of the model in a separate multi-institutional cohort. This multicenter investigation involving 15 academic institutions prospectively collected samples from 194 revision total knee arthroplasties (TKA) and 184 revision hip arthroplasties (THA) between 2017–2019. Patients undergoing reimplantation or spacer exchange procedures were excluded. Synovial fluid, deep tissue and swabs were obtained at the time of surgery and shipped to MicrogenDx (Lubbock, TX) for NGS analysis. Deep tissue specimens were also sent to the institutional labs for culture. All patients were classified per the 2018 Consensus definition of PJI. Microbial DNA analysis of community similarities (ANCOM) was used to identify 17 candidate bacterial species out of 294 (W-value >50) for differentiating infected vs. noninfected cases. Logistic Regression with LASSO model selection and random forest algorithms were then used to build a model for predicting PJI. For this analysis, ICM classification was the response variable (gold standard) and the species identified through ANCOM were the predictor variables. Recruited cases were randomly split in half, with one half designated as the training set, and the other half as the validation set. Using the training set, a model for PJI diagnosis was generated. The optimal resulting model was then tested for prediction ability with the validation set. The entire model-building procedure and validation was iterated 1000 times. From the model set, distributions of overall assignment rate, specificity, sensitivity, positive predictive value (PPV) and negative predicative value (NPV) were assessed.Introduction
Methods
Periprosthetic joint infection (PJI) remains the main cause of failure in primary and revision total knee arthroplasties (TKAs). Local delivery of antibiotics, mainly antibiotic-loaded bone cement (ALBC), is commonly employed to prevent PJI. Over the past decade, tantalum and porous titanium have been successfully utilized as metaphyseal fixation devices to address bone loss and improve biologic fixation during revision TKA. However, no study has examined the antimicrobial properties compared to bone cement. The purpose of this study was to compare the ability of tantalum, 3D porous titanium, antibiotic-loaded bone cement (ALBC) and smooth titanium alloy (STA) to inhibit Staphylococci bacterial agents in an in vitro medium environment, based on the evaluation of the zone of inhibition (ZOI) and the antibacterial activity duration. Our study hypothesis was that we will found no significant difference between groups to inhibit Methicillin-Sensitive or Methicillin-Resistant Staphylococcus aureus (MSSA/MRSA) agents. Thirty beads made of 3 different materials (tantalum/ 3D porous titanium/ STA) were bathed during 1hour inside of a solution made of 1g vancomycin with 20-mL of sterile water for injection (bath concentration: 50 mg/mL). Ten 1cm3 cylinders were also created mixing standard surgical cement with 1g of Vancomycin in standardized sterile molds (ALBC beads). Finally, thirty beads made of tantalum/ 3D porous titanium/ STA were bathed in phosphate buffered saline solution to act as a control group. Cylinders were then placed on agar plates inoculated with MSSA and MRSA. Inhibition zone diameters were measured each day and cylinders were transferred onto a new inoculated plate. Inhibition zones were measured with a manual Vernier caliper and with automated software. The mean inhibition zones between groups were compared using the Wilcoxon Test.Introduction
Methods
Two-stage exchange arthroplasty remains the gold standard for treatment of PJI with reported success rates of 85–90%. Complications that occur during treatment are often not reported or considered in the success rate. The purpose of this study was to analyze complications in patients undergoing two-stage exchange and determine when they occur. We analyzed all patients that underwent two-stage exchange arthroplasty for treatment of chronic PJI of the knee from 2010 to 2018. We categorized complications as medical vs. surgical. The intervals for complications were divided into: interstage, early post re-implant (3 months) and late post re-implant (3 months to minimum 1 year). Minimum follow-up to evaluate complications was one year.Introduction
Methods
Total Knee Arthroplasty (TKA) has been demonstrated to drastically improve a patient's quality of life. The outcomes following TKA are often reported by subjective patient reported outcome measurements (PROMs). However, there are few objective outcome measures following TKA, limiting the amount of information physicians can use to effectively guide a patient's recovery, especially in the first 3 weeks. Newly developed knee sensors have been able to ameliorate this problem by providing the physician with previously unobtainable objective data. Our study aims to evaluate the use of a wearable knee sensor device to measure functional outcomes (range of motion and steps) in real time. 29 patients who underwent primary, unilateral TKA were recruited for this IRB approved study. Patients were instructed how to use the device and associated mobile phone application preoperatively (Figure 1) and provided knee sensors to wear postoperatively (Figure 2). Patients wore the device for 3 weeks postoperatively to allow for data collection. The device recorded range of motion, number of steps, and percentage of physical therapy exercises completed. Patients were grouped by gender, age (<69 or >=70 years old), and BMI (<30 and >=30 kg/m2) for analysis of functional outcome measurements (maximum flexion, minimum extension, and number of steps). Unpaired two-sample t-tests were used to analyze differences between the groups.Introduction
Methods
Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty. The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. We performed a retrospective study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision total knee arthroplasty. Patient demographics, etiology of dislocation, presurgical deformity, intraoperation component position, complications, reoperation and knee society scores were collected.Background
Methods
Metaphyseal fixation during revision total knee arthroplasties (TKAs) is important, but potentially challenging with historical cone designs. Material and manufacturing innovations have improved the size and shape of cones available, and simplified requisite bone preparation. In a very large series, we assessed implant survivorship, radiographic results, and clinical outcomes of new porous 3-D printed titanium metaphyseal cones featuring a reamer-based system. We reviewed 142 revision TKAs using 202 cones (134 tibial and 68 femoral) from 2015 to 2016. Sixty cases involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. Mean age was 66 years, with 54 % females. Mean BMI was 34 kg/m2. Patients had a mean of 2.4 prior surgeries and 48% had a history of periprosthetic infection. Mean follow-up was 2 years.Introduction
Methods
Rates of readmission and reoperation following primary total knee arthroplasty (TKA) are under scrutiny due to new payment models, which penalize these negative outcomes. Many prior studies have demonstrated the risk of perioperative complications among patients with obesity. However, an elevated complication rate among patients with poor nutrition, as measured by hypoalbuminemia, has also been reported. We sought to determine whether controlling for hypoalbuminemia would mitigate the effect that prior authors had identified in patients with obesity. In addition, we hoped to identify an albumin threshold above which risk of readmission and reoperation would be minimized. We reviewed the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database for the period of 2008–2016 to evaluate the rates of perioperative complications among primary TKA patients by obesity category and albumin level. Patients were divided into groups according to World Health Organization obesity category and continuous as well as dichotomous albumin level. The primary outcomes were readmission and reoperation within 30 days of surgery. Patients without BMI or albumin data were excluded, as were patients undergoing surgery for the treatment of fracture or bone tumor. Univariate logistic regression compared predictive value of body mass index and albumin on incidence of these outcomes, using the normal weight and albumin > 3.5 g/dL groups as controls. Multivariate logistic regression modeling controlled for age, gender, and comorbidity status. Receiver operator curves (ROC) were generated to determine if an albumin threshold could be determined, above which risk for these complications would be minimized.Introduction
Materials and Methods
The Centers for Medicare and Medicaid Services (CMS) removed total knee arthroplasty (TKA) from inpatient-only status in 2018. Our goal was to measure the adoption of outpatient TKAs, the impact on re-treatment rates, and the economic implications for hospitals. We utilized 100% national Medicare Part A fee-for-service (FFS) patient-level claims data for 2017–2018. We excluded DRG 469 TKAs since they are unlikely to be outpatient candidates, which left 257,107 primary TKAs in 2017 and 264,393 in 2018. We examined the time trend in monthly case volume and 30-day retreatment rate (defined as percent of patients having a second TKA within 30 days of the first. We calculated the loss in revenue for a hospital by multiplying the decrease in payment rate between inpatient and outpatient by the outpatient and total 2018 TKA volume.Introduction
Methods
We designed this study to compare 30-day complications and length of hospital stay between patients undergoing total knee arthroplasty (TKA) with general anesthesia, to those undergoing TKA with spinal, epidural anesthesia, or Monitored Anesthesia Care (MAC, a combination of local anesthesia with sedation and analgesia provided by an anesthesiologist) with or without regional nerve blocks. We identified patients ≥18 years undergoing TKA between the years of 2006 and 2017 from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP). We collected patient demographics, anesthesia type, 30-day complications, length of operation and hospital stay from the database. We used multivariable regression to compare complications and length of stay (LOS) between anesthesia types, while adjusting for relevant covariablesIntroduction
Methods
Patients with solid organ transplant have been shown to have increased risk of complications following TKA compared to non-transplant patients. The risk of AKI in KTx is reported to be as high as 15.6 % and associated with increased morbidity, and length of stay (LOS). Our aim was to determine the incidence of AKI in KTx undergoing primary and revision TKA and to identify risk factors for its occurrence and its effect on allograft function 1 year postoperatively. Using the orthopedic and transplant databases we designed a case-control study of 82 patients undergoing 101 TKA between 2000 and 2018 at our institution. The average age at surgery was 65 years (range 35–83); 58% male and 98% white. AKI was defined per KIDGO guidelines.Introduction
Methods
In the setting of a “dry” aspiration, saline lavage is commonly used to obtain a sample for analysis. The purpose of this study is to prospectively determine the impact of saline lavage on synovial fluid markers in revision arthroplasty. 79 patients undergoing revision hip (19) and knee (60) arthroplasty were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry-tap (“pre-lavage”) followed by subsequent injection with 20 mL of normal saline and re-aspiration (“post-lavage”). Pre and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared. Statistical analyses utilized the Wilcoxon signed-rank test.Background
Methods
The use of the haptically bounded saw blades in robotic-assisted total knee arthroplasty (RTKA) can potentially help to limit surrounding soft-tissue injuries. However, there are limited data characterizing these injuries for cruciate-retaining (CR) TKA with the use of this technique. The objective of this cadaver study was to compare the extent of soft-tissue damage sustained through a robotic-assisted, haptically guided TKA (RATKA) A total of 12 fresh-frozen pelvis-to-toe cadaver specimens were included. Four surgeons each prepared three RATKA and three MTKA specimens for cruciate-retaining TKAs. A RATKA was performed on one knee and a MTKA on the other. Postoperatively, two additional surgeons assessed and graded damage to 14 key anatomical structures in a blinded manner. Kruskal–Wallis hypothesis tests were performed to assess statistical differences in soft-tissue damage between RATKA and MTKA cases.Objectives
Methods
Optimal perioperative fluid management has not been established in patients undergoing orthopaedic surgical procedures. Our purpose was to investigate the effects of perioperative fluid management on patients experiencing TKA. One hundred thirty patients who met inclusion criteria undergoing primary unilateral TKA were prospectively randomized into traditional (TFG) vs. oral (OFG) perioperative fluid management groups. The TFG had a predetermined (4L) amount of intravenous fluids (IVF) administered in the perioperative period. The OFG began drinking a minimum of three, 20-ounces servings of clear fluids daily for three days prior to surgery. This cohort also drank 10-ounces of clear fluids 4 hours prior to surgery. Perioperative IVF were discontinued when the patient began oral intake or when the total amount of IVF reached 500mL. Outcome measures included: body-weight (BW) fluctuations, knee motion, leg girth, bioelectrical impendence, quadriceps activation, functional outcomes testing, KOOS JR, VR-12, laboratory values, vital signs, patient satisfaction, pain scores, and adverse events.Background
Methods
Low serum Vitamin D (VitD) levels are often found in patients being investigated for Total Knee Arthroplasty (TKA). VitD deficiency is associated with poor pre/post-operative functional scores and higher rate of complications. Studies report VitD as an important modifiable risk factor to improve outcomes post TKA. Aim of our study was 1) To examine the trajectory of VitD in TKA patients over 2 weeks, which included VitD sufficient and deficient patients who were supplemented orally or intramuscularly (IM) for comparision. 2) To compare early (2weeks) functional recovery in VitD sufficient and deficient patients.Introduction
Aim
There is insufficient data on the trends of anticoagulation after total knee arthroplasty (TKA) in the USA, and the efficacy and safety of rivaroxaban, beyond randomized clinical trials and small cohort studies. Using the Truven Health MarketScan database, we retrospectively evaluated new anticoagulation prescriptions after elective TKA from 2010 to 2015. The frequency of deep vein thrombosis (DVT), pulmonary embolism (PE), and adverse events, within 90 days, were then evaluated in 24,856 new users of warfarin and 21,398 new users of rivaroxaban in commercially insured patients (COM), and 15,483 new users of warfarin and 8,997 new users of rivaroxaban in Medicare supplement patients (MED). Data was analyzed by odds ratios using logistic regression models with stabilized inverse probability treatment weighting.Introduction
Patients and Methods
Surgeons performing a total knee replacement (TKR) have two techniques to assist them achieve proper bone resections and ligament tension – gap balancing (GB) and measured resection (MR). GB relies on balancing ligaments prior to bony resections, whereas bony resections are made based on anatomical landmarks in MR. Many studies have been done to compare the implant migration and kinematics between the two techniques, but the results have been varied. However, these studies have not been done on modern anatomically designed prostheses using radiostereometric analysis (RSA). Anatomical designs attempt to mimic the normal knee joint structure to return more natural kinematics to the joint, with emphasis on eliminating both paradoxical anterior motion and reduced posterior femoral rollback. Given the major design differences between anatomical and non-anatomical prostheses, it is important to investigate whether one surgical technique may have advantages another. We hypothesize that there would be no difference between GB and MR techniques in implant migration, but that GB might provide better knee kinematics. Patients were recruited to receive an anatomically designed prosthesis and randomized to groups where the GB or MR technique is used. For all patients in the study, RSA images were acquired at a 2 week baseline, as well as at 6 weeks, 3 months, and 6 months post-operatively. These images were used to collect the maximum total point motion (MTPM) of the tibial and femoral implant components relative to the bone using a model-based RSA software. A series of RSA images were also acquired at 3-months post-operatively at different knee flexion angles, ranging in 20° increments from 0° to 100°. Model-based RSA software was used to obtain the 3D positions and orientations of the femoral and tibial components, which were used to obtain the anterior-posterior (AP) contact locations for each condyle.Introduction
Methods
Patients are often cautioned against a high level of activity following knee arthroplasty. The purpose of this study is to report on implant survivorship and outcomes of high activity patients compared to low activity patients after TKA. We identified 1611 patients (2038 knees) who underwent TKA with 5-year minimum follow-up. Patients were divided in two groups: Low activity (LA) (UCLA ≤5) and high activity (HA) (UCLA ≥ 6). Pre-and postoperative ROM, Knee Society scores, complications and reoperations were evaluated.Introduction
Methods
