Cementless fixation in total knee arthroplasty has been proposed to offer advantages long-term once osteointegration has occurred as there is no substrate between the implant and the bone to fail. Radiostereometric analysis (RSA) is a useful tool to study fixation, but typically focused on early migration in the first two post-operative years. Few studies have looked at 10-year RSA migration in cementless fixation and those that have contain small numbers of subjects. The objective of this study was to compare implant migration and inducible displacement between cemented and cementless TKA at 10 years and to compare the 10-year migration to the 2-year data in an effort to validate the predictive modelling of RSA. Subjects who had previously participated in RSA migration studies with 2-year follow-up were recruited to return for a long-term follow-up exam, at least 10 years from their surgery. The implants under study included two cemented designs from two manufacturers and one porous metal monoblock cementless design. At the 10-year visit, subjects had supine RSA exams to determine long-term migration as well as a loaded exam (single leg stance) to determine inducible displacement. Differences between cemented and cementless groups were evaluated with the Mann Whitney U test and Spearman's rank correlation coefficients were calculated for early and late migrations. Significance was set at p < 0.05.Introduction
Methods
Uncemented highly porous titanium implants have been shown to promote osseointegration, and may result in a durable construct for total knee arthroplasty (TKA). Given the mixed results of uncemented TKA, it is important to evaluate the early stability for this product. The objective of the following study was to use radiostereometric analysis (RSA) to assess early fixation of a highly porous tibial baseplate and metal backed patella. Twenty-seven patients (mean age 64 years, 30% female) undergoing primary TKA consented to participate in this prospective cohort study. All patients received a highly porous tibial baseplate, a metal backed patella and tantalum RSA bone markers. Implant migration was assessed using model-based RSA at 1.5, 3, 6, 12 and 24 months post-operative. Patient reported outcome measures were captured using the same follow-up schedule, and compared to pre-operative measures.Introduction
Methods
Polyethylene wear and osteolysis remain a concern with the use of modular, fixed bearing total knee arthroplasty (TKA). A variety of highly cross-linked polyethylenes (XLPs) have been introduced to address this problem, but there are few data on the results and complications of this polyethylene in posterior-stabilized knee prosthesis. We have previously reported an interim analysis of a study comparing polyethylene tibial liners. This is a prospective randomized study of one modular posterior-stabilized total knee arthroplasty by a single surgeon. 265 patients (329 knees) were randomized to receive a standard compression molded liner (SP) or a highly cross-linked (6.5 CGy electron-beam irradiated and remelted) polyethylene liner (XLP). Patients were evaluated clinically using the classic Knee Society scores, LEAS score, presence of a knee effusion, and by standard radiographs for radiolucent lines and osteolytic lesions. The analysis was performed at a mean of 6 years (range, 2–11 years).Introduction
Methods
Modern implant systems offer a variety of options to address the posterior cruciate ligament (PCL) and afford stability in primary total knee arthroplasty (TKA). One system has three bearing options for cruciate retaining (CR) TKA: standard CR bearing (CR-S) with 3° posterior slope and no posterior lip; CR lipped bearing (CR-L) with no slope and small posterior lip, and deep-dished anterior stabilized bearing (CR-AS) with large anterior build-up to compensates for deficient or lax PCL. We previously reported on 1940 patients (2449 CR-TKA) at early follow-up comparing these three CR bearings and found CR-AS bearings had greater improvement in ROM and lower rate of manipulation despite their use in patients with greater preoperative deformity and lower ROM. The purpose of this study was to review a broader series by a single surgeon-designer with minimum 2-year follow-up to determine if there were differences between bearing types in terms of clinical outcomes and survival. From 2003 to 2014, 3348 patients (4500 knees) underwent primary CR-TKA and were available for review with minimum 2-year follow-up. An algorithmic approach to constraint was employed, choosing the least amount necessary to afford stability. Bearings used were 3883 CR-S (86%), 256 CR-L (6%), and 361 CR-AS (8%). CR-S bearings were used in patients with less preoperative tibiofemoral deformity (p=0.0316), less flexion contracture (p<0.0001), and better ROM (p<0.0001), but more mediolateral instability (p<0.0001) than CR-AS bearings.Introduction
Methods
First generation cephalosporins remain the gold standard perioperative antibiotic for total hip and knee arthroplasty (THA, TKA). However, some patients have documented or self-reported allergies to antibiotics, most commonly penicillin, that result in changes to perioperative antibiotic coverage. Furthermore, patients testing positive for methicillin resistant staphylococcus aureus (MRSA) represent another group where an alternative to cefazolin, typically vancomycin, is often chosen for perioperative prophylaxis. The aims of this study were to 1) characterize the antibiotic choices for perioperative prophylaxis at the time of primary TKA and THA, 2) assess the efficacy of a preoperative antibiotic allergy testing program, and 3) determine rates of periprosthetic joint infection (PJI) based on perioperative antibiotic regimen. We evaluated all patients undergoing primary TKA or THA at a single academic institution from January 2004-May 2017, yielding a cohort of 29,695 patients. A series of institutional databases were combined to determine which patients underwent antibiotic allergy testing prior to surgery, outcomes from the allergy consultation, perioperative antibiotic management strategy, and survivorship free of infection until final follow-up.Introduction
Methods
Antibiotic-impregnated bone cement (AIBC) has been used for decades to treat and prevent post-operative infections in joint arthroplasty. Local delivery of antibiotics may theoretically have a bactericidal effect, however evidence supporting this is controversial and literature suggests its prophylactic use in primary total knee arthroplasty (TKA) is seldom justified. With evolving standards of care, historical data is no longer relevant in addressing the efficacy of AIBC in the contemporary TKA. The purpose of this study was to evaluate outcomes following primary TKA using AIBC and regular non-AIBC by comparing rates of surgical site infection (SSI) and prosthetic joint infection (PJI). A retrospective review was conducted of all cemented primary TKA procedures from a large institutional database between January 1, 2015 and December 31st, 2016. This identified 6,073 cases, n=2,613 in which AIBC was used and n=3,460 cases using bone cement without antibiotics. Patients were stratified into low risk and high-risk groups based on age (>65 years), BMI (>40), and Charlson Comorbidity Index (CCI; >3). Medical records were reviewed for diagnoses of SSI (skin and superficial wound infections) and PJI (deep joint infections requiring surgery) over a 2-year postoperative period. Univariate analysis and multivariate regression models were used to ascertain the effects of cement type, patient factors (age, gender, BMI, CCI), operative time, and length of stay on infection rates. Additionally, mixed models (adjusted for gender, age, race, BMI, and CCI) were built to account for surgeon variability.Introduction
Methods
Periprosthetic joinTt infection (PJI) remains an uncommon, yet devastating complication of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Debridement with antibiotics and implant retention (DAIR) provides an alternative to staged revision. Chronic infection is considered to be a contraindication to DAIR, however, outcomes stratified by chronicity have not been documented. We performed a retrospective review of all DAIR cases performed at our institution between 2008–2015. Timeframe to treatment was categorized as acute (< 6 weeks since surgery), chronic (>6 weeks since surgery) or acute hematogenous (previously well-functioning prosthesis). Treatment failure was defined as reoperation during the first 90-days following DAIR. Univariate analysis (Mann-Whitney U and Chi-square; p<0.05) and generalized estimating equations (GEE) were used with multiple comparison adjustment by Tukey-Kramer method (α = 0.05).Introduction
Methods
Whether anterior referencing (AR) or posterior referencing (PR) are optimal to position and size the femoral component in Total Knee Arthroplasty (TKA) remains controversial. This controversy stems, in part, from a lack of understanding of whether one technique more consistently balances the medial/lateral collateral ligaments (MCL & LCL) in flexion and extension. Therefore, our goal was to compare AR and PR in terms of: (1) maximum MCL and LCL forces in passive flexion, and (2) medial and lateral gaps at full extension and 90‖ of flexion. In addition, we identified geometric landmarks that could help predict the ligament forces during flexion. Computational models of six knees were virtually implanted with TKAs based on our previously-developed framework. AR and PR were simulated in each of the six models. A Posterior Stabilized implant was utilized. Standard AR and PR cuts and component positioning were simulated with the femoral component aligned parallel to the transepicondylar axis. In both AR and PR models, the distal femoral cut and the proximal tibial cut were perpendicular to the femoral and tibial mechanical axis, respectively. The amount of posterior bone resected with AR knees ranged from 4.2 to 10.8 mm, and with PR knees ranged from 4.2 to 8 mm. Ligament properties were standardized to reflect a balanced knee at full extension. Passive flexion under 500 N of compression was applied and the MCL and LCL forces were predicted. A new measure, the MCL ratio, that incorporated the femoral insertion of the anterior fiber of MCL relative to the posterior and distal femoral cuts was estimated (Fig. 1). A varus/valgus moment of 6 Nm was applied at full extension and 90‖ of flexion, and the corresponding lateral and medial gaps were measured.Introduction
Methods
Opioid abuse is a national epidemic. Traditional pain management after total knee arthroplasty (TKA) relied heavily on opioids. The evidence that in-hospital multimodal pain management (MMPM) is more effective than opioid-only analgesia is overwhelming. There has been little focus on post-discharge pain management. The purpose of this study was to determine whether MMPM after TKA could reduce opioid consumption in the 30-day period after hospital discharge. This was a prospective, two-arm, comparative study with a provider cross-over design. The first arm utilized a standard opioid-only (OO) prn regimen. The second arm utilized a 30-day MMPM regimen (standing doses of acetaminophen, metaxalone, meloxicam, gabapentin) and opioid medications prn. Surgeons crossed over protocols every four weeks. The primary outcome measure was VAS pain score. Secondary outcome measures included morphine milligram equivalents (MME) consumed, failure of the protocol, and manipulation under anesthesia (MUA). A pre-hoc power analysis was performed for the primary outcome measure and an intent-to-treat analysis was done utilizing a longitudinal mixed model.Introduction
Methods
Poor osseointegration of cementless implants is the leading clinical cause of implant loosening, subsidence, and replacement failure, which require costly and technically challenging revision surgery. The mechanism of osseointegration requires further elucidation. We have recently developed a novel titanium implant for the mouse tibia that maintains in vivo knee joint function and allows us to study osseointegration in an intra-articular, load-bearing environment. Vascular endothelial growth factor (VEGF) is one of the most important growth factors for regulation of vascular development and angiogenesis. It also plays critical roles in skeletal development and bone repair and regeneration. A specialized subset of vascular endothelium, CD31hiEMCNhi cells displaying high cell surface expression of CD31 and Endomucin, has been reported to promote osteoblast maturation and may be responsible for bone formation during development and fracture healing. Because of their potential role in osseointegration, the aim of this study was to use our mouse implant model to investigate the role of VEGF and CD31hiEMCNhi endothelium in osseointegration. Under an IACUC-approved protocol, the implant was inserted into the right tibia of 16-week-old female C57BL/6 mice (N = 38). The mice were then randomized into 2 groups: Control group (N=19) and Anti-VEGFR group (N=19). A cocktail of VEGFR-1 antibody (25mg/kg) and VEGFR-2 antibody (25mg/kg) was given to the mice in the Anti-VEGFR group by intraperitoneal injection every third day starting immediately after surgery until euthanasia. An equivalent amount of an isotype control antibody was given to the control group. Flow cytometric (N = 4/group) and immunofluorescencent (N = 3/group) analyses were performed at 2 weeks post-implantation to detect the distribution and density of CD31hiEMCNhi endothelium in the peri-implant bone. Pull-out testing was used at 4 weeks post-implantation to determine the strength of the bone-implant interface.Introduction
Methods
Although we know that smoking damages health, we do not know impact of smoking on a patient's outcome following primary knee arthroplasty (KA). In the UK, clinical commissioning groups (CCGs) have the authority (& funds) to commission healthcare services for their communities. Over the past decade, an increasing number of CCGs are using smoking as a contraindication for patients with end-stage symptomatic knee arthritis being referred to a specialist for due consideration of KA without any clear evidence of the associated risks & benefits. The overall objective of this study is to compare clinical outcomes after knee arthroplasty surgery in smokers, ex-smokers & non-smokers. We obtained data from the UK Clinical Research Practice Datalink (CPRD) that contains information on over 11 million patients (7% of the UK population) registered at over 600 general practices. CPRD data was linked to Hospital Episode Statistics, hospital admissions & Patient Reported Outcome Measures (PROMs) data. We collected data on all KAs (n=64,071) performed over a 21-year period (1995 to 2016). Outcomes assessed included: local & systemic complications (at 6-months post-surgery): infections (wound, respiratory, urinary), heart attack, stroke & transient ischaemic attack, venous thromboembolism, hospital readmissions & GP visits (1-year), analgesic use (1-year), surgical revision (up to 20-years), mortality (90-days and 1-year), & 6-month change from pre-operative scores in Oxford Knee Score (OKS). Regression modelling is used to describe the association of smoking on outcomes, adjusting for confounding factors.Introduction
Methods
In the lower extremity, lymphedema is characterized by fluid buildup and swelling which can lead to fibrosis of the skin and recurring soft-tissue infections. Risk factors include obesity, older age, lower extremity surgery, and radiotherapy. There is currently a paucity of data examining the impact of lymphedema in primary total knee arthroplasty (TKA). The purpose of this study was to review outcomes following primary TKA performed in patients with lymphedema compared to a matched cohort with primary osteoarthritis. Over a 19-year period (1998–2016), 144 patients underwent primary TKA with a preceding diagnosis of ipsilateral lymphedema (Table 1). There were 114 (79%) females, a mean age of 69 years, and mean BMI of 37.1 kg/m2. Mean follow-up was 7-years (range 2–17 years). A blinded analyst completed a 1:2 match of patients with lymphedema to a group of patients without lymphedema undergoing primary TKA for osteoarthritis during the same period. Matching criteria included sex, age, date of surgery, and BMI. Matched controls included 228 (79%) females along with a mean age and BMI of 69 and 36.4 kg/m2. The mean follow-up for the comparison cohort was 8 years (range 2–18 years). There were no significant differences between groups on the evaluated baseline parameters. Results: Patients with a history of lymphedema were at a significantly increased risk of revision TKA (HR 7.60, P<0.001), reoperation for any cause (HR 2.87, P<0.001), and postoperative infection (HR 6.19, P<0.001). Patients with lymphedema were also at increased risk for periprosthetic fracture (p=0.04) and tibial component loosening (p=0.01). Morbid obesity increased the risk of reoperation (HR 2.11, p=0.02) and trended toward increased risk of revision TKA (HR 2.29, p=0.059) and infection (HR 2.37, p=0.06). Discussion: Patients with lymphedema are at significantly increased risk of revision, reoperation, and infection following primary TKA. This data highlights the need for appropriate patient counseling in this population and optimization of lymphedema management before and after TKA.Introduction
Methods
In major orthopaedic departments, typically several total knee systems are used. Each system requires several sets of instruments, each set with many trays of complicated and expensive parts. The logistics and costs of maintainance are considerable. Our overall goal is to investigate the feasibility of autoclavable single-use 3D printed instruments made from a polymeric material, used for any type of total knee design. The procedure will be standardized and adjustments easy to implement. Each set will be packaged individually, and used for a single case. There are many aspects to this study; in this part, the aims are to identify suitable materials for autoclavability and strength, and then to compare the accuracy of a novel design of 3D printed tibial cutting guide with a current metallic guide. Test samples were designed to simulate shapes in current instruments, such as mating pegs and holes, threaded screws, and slotted blocks. Each set was produced in biocompatible materials, ABS-M30i, VeroClear (MED610), Ultem1010, and Nylon 12. Each part was laser scanned, and then imaged virtually using a reverse engineering software (GeoMagic). Manual measurements of key dimensions were also made using calipers. The parts were autoclaved using a standardized protocol, 30 minutes at 250° F. All parts were re-scanned and measured to determine any changes in dimensions. To test for strength and abrasion resistance, the slotted blocks were pinned to sawbones model tibias, and an oscillating saw used to cut through the slot. A compact 3D printed tibial cutting guide was then designed which fitted to the proximal tibia and allowed varus-valgus, tibial slope and height adjustments. A small laser attached to the guide projected to a target at the ankle. Tests were made on 20 sawbones, and compared with 20 with a standard metal cutting guide. Digitization was used to measure the angles of the cuts.Introduction
Methods
The aim of this study was to evaluate the surface damage, the density of crosslinking, and oxidation in retrieved antioxidant-stabilized highly crosslinked polyethylene (A-XLPE) tibial inserts from total knee arthroplasty (TKA), and to compare the results with a matched cohort of standard remelted highly crosslinked polyethylene (XLPE) inserts. A total of 19 A-XLPE tibial inserts were retrieved during revision TKA and matched to 18 retrieved XLPE inserts according to the demographics of the patients, with a mean length of implantation of 15 months (1 to 42). The percentage areas of PE damage on the articular surfaces and the modes of damage were measured. The density of crosslinking of the PE and oxidation were measured at loaded and unloaded regions on these surfaces.Aims
Materials and Methods
The use of stem cell and platelet-rich plasma (PRP) injections for knee osteoarthritis (OA) is extremely controversial and at best experimental. These treatments are being given to patients across the nation for “cash only payments”. Our objectives were (1) to determine the proportion of board certified orthopedic surgeons who offer stem cell or PRP treatment for knee OA, (2) how much the practices charge for those treatments and (3) if members of the knee society use these therapies. Board certified orthopedic surgeons’ offices in our county were identified by their AAOS active membership. Knee society membership roll was also utilized. Offices were contacted by telephone and presented with a hypothetical patient with end stage knee osteoarthritis searching for specific treatment (stem cells or PRP injections). T-test was used to compare the Dade county board certified orthopedists to knee society members.Introduction
Methods
Dialysis has been associated with increased complication rates following total knee arthroplasty (TKA). However, the current literature on this topic is limited and does not distinguish between hemodialysis (HD) and peritoneal dialysis (PD). It is unknown if the type of dialysis influences the risks of adverse outcome. The purpose of this study was to determine if infection and complication rates after TKA differ based on the mode of dialysis. Patients undergoing primary TKA from 2005 to 2014 were identified in the Medicare database. Patients with PD were matched 1:1 to patients with HD and 1:3 with patients who were not receiving either form of dialysis. Multivariate regression analysis was performed to examine several adverse events including the incidence of infection at 1 year and readmission to the hospital at 30 days.Introduction
Methods
The effectiveness of patient specific instrumentation (PSI) to perform total knee arthroplasty (TKA) remains controversial. Multiple studies have been published that reveal conflicting results on the effectiveness of PSI, but no study has analyzed the contact kinematics within knee joints replaced with the use of PSI. Since a departure from normal kinematics can lead to eccentric loading, premature wear, and component loosening, studying the kinematics in patients who have undergone TKA with PSI can provide valuable insight on the ability of PSI to improve functionality and increase longevity. The goal of the present study was to compare femoral and tibial component migration (predictive of long-term loosening and revision) and contact kinematics following TKA using conventional instruments (CI) and PSI based surgical techniques. The study was designed as a prospective, randomized controlled trial of 50 patients, with 25 patients each in the PSI and CI groups, powered for radiostereometric analysis (RSA). Patients in the PSI group received an MRI and standing 3-foot x-rays to construct patient-specific cut-through surgical guides for the femur and tibia with a mechanical limb alignment. All patients received the same posterior-stabilized implant with marker beads inserted in the bone around the implants to enable RSA imaging. Patients underwent supine RSA exams at multiple time points (two and six weeks, three and six months, and one and two years). At 2 years post-op, a series of RSA radiographs were acquired at different knee flexion angles, ranging in 20° increments from 0° to 120°, to measure the tibiofemoral contact kinematics. Migrations of the femoral and tibial components were calculated using model-based RSA software. Kinematics were measured for each condyle for magnitude of excursion, contact location, and stability.Introduction
Methods
Clinical observations suggest mid-flexion instability may occur more commonly with rotating platform (RP) total knee arthroplasty (TKA), including increased revision rates and patient-reported instability and pain. We propose that increased gap laxity leads to liftoff of the lateral femoral condyle with decreased conformity between the femoral component and polyethylene (PE) insert surface leading to PE subluxation or dislocation. The objectives of this study were to define “at risk” loading conditions that predispose patients to PE insert subluxation or spinout, and to quantify the margin of error for flexion/extension gap laxity in preventing these adverse events under physiologic loading conditions. Biomechanical testing was performed on six fresh frozen cadaveric knees implanted with a posterior stabilized RP TKA using a gap balancing technique. Rotational displacement and torque were measured over time, while stiffness, yield torque, max torque and displacement were calculated using a post-processing, custom MatLab code. Revision with varying size femoral components (size 3–6) and PE insert thicknesses (10–15mm), by downsizing one step, were used to create a spectrum of flexion/extension gap mismatch. Each configuration was subjected to three loaded testing conditions (0°, 30° and 60° flexion) in balanced and eccentric varus loading, known to represent daily clinical function and “at risk” circumstances.Introduction
Methods
The prescription of opioids has increased in the last two decades. Recently, several states have developed online Prescription Drug Monitoring Programs aimed at preventing overprescribing of controlled substances. Unicompartmental knee arthroplasty (UKA) has been shown to provide improved early functional outcomes, faster recovery, and less postoperative morbidity and pain than total knee arthroplasty (TKA). The aim of this study is to evaluate differences in opioid prescription requirements between patients undergoing TKA and UKA. We retrospectively reviewed consecutive series of primary TKA from January 2017 to July 2017 and primary UKA from January 2016 to July 2017 using standardized perioperative pain protocols. All patients that underwent any other procedure 6 months prior to and after index surgery were excluded, resulting in 740 TKA and 241 UKA. Demographic and comorbidity information was collected for all patients. Opioid prescriptions, morphine milligram equivalents (MME), sedatives, benzodiazepines, and stimulants were collected from State Controlled Substance Monitoring website 6 months prior and after index procedures. Univariate and multivariate analysis were performed for patients that had a second prescription and continued use (defined as more than 6 months postoperatively).Introduction
Methods
There is little published evidence regarding cannabis or cannabinoid use among orthopedic patients, yet there is increasing public attention on its possible role in treating various medical conditions including pain. California passed legislation legalizing cannabis for medical treatment in 2003 and recreational use in 2018. All patients undergoing total joint arthroplasty (TJA) at our institution are screened preoperatively with a urine toxicology (UTox) screen. Though a positive test for other substances triggers surgery cancellation, a positive screen for cannabis and/or opiates does not impact whether surgery is performed. We sought to quantify the prevalence of cannabinoid and opioid use among patients with chronic pain from end-stage hip and knee osteoarthritis who underwent arthroplasty at our institution in 2012 and 2017. Institutional Review Board approval was obtained. A retrospective chart review was performed for all patients with severe arthritis who underwent total hip and knee arthroplasty (THA and TKA) at our institution during the calendar years 2012 and 2017. Patients were excluded if TJA was performed for acute trauma or if no pre-operative UTox screen was obtained. The UTox screen was used to determine preoperative cannabis and opioid use. Chi-squared testing was performed, and significance was defined as p<=0.05.Introduction
Methods
Recovery after total knee arthroplasty (TKA) may take longer than patients expect. Furthermore, there are a subset of patients who still experience pain and dissatisfaction despite normal physical examination, radiographs, and laboratory analysis. Corticosteroid injection (CSI) is commonly used nonsurgical treatment for painful knee arthritis. However, the efficacy of CSI in patients with a painful TKA remains unknown. A retrospective charge review was performed to identify a cohort of patients who had a primary TKA performed between 2015 and 2016 and later received a CSI. All TKAs and CSIs were performed by a fellowship-trained arthroplasty surgeon. Patients receiving a CSI underwent a clinical exam, laboratory analysis to rule out infection, and radiographic evaluation prior to injection. Patient variables were recorded and a survey assessed the efficacy of the injection. The survey response rate was 63.6%.Introduction
Methods
The aim of this study was to evaluate the effects of posterior tibial slope (PTS) and posterior condylar offset (PCO) on patient-reported pain and function one year after TKA. A total of 500 patients from 11 clinics in 6 countries were enrolled into a prospective, multicenter study. All patients were indicated for primary TKA for OA and received components from a single manufacturer. All liners were made from vitamin-E stabilized, highly crosslinked (95 kGy) polyethylene; 54.7% were posterior stabilized (PS) and the remaining were cruciate-retaining. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was administered at the one-year follow-up visit. The KOOS pain and activities in daily life (ADL) sub-scores were dichotomized and served as the primary outcomes. Dichotomization was done with the patient acceptable symptom state (PASS), defined by previous studies as the value of the PROM above which patients deem their state as acceptable (84.5 points for KOOS pain and 83.0 points for KOOS ADL). Plain lateral radiographs were taken and assessed for PTS (Figure 1) and PCO (Figure 2). PTS was categorized as above (excessive flexion), within (ideal), or below (extension) the safe zone of 0° − 7° of flexion. PCO increases or decreases of greater than 3mm were compared against no change (≤ 3mm). Each of the two sagittal positioning metrics was tested against the KOOS pain and ADL PASS at one year.Introduction
Methods
The modern modular implants allow surgeons to combine different combinations of components within the same brand of which some may have completely different design. During 1999–2012 the same cemented femur component was used together with a cemented stemmed tibia baseplate and also against a cemented pegged tibia baseplate. We decided to compare the revision rate of total knee arthroplasties (TKAs) using these two tibia baseplates. This is a register study. During 1999–2012, 32,429 cemented, CR TKA's of a specific brand were reported to the Swedish Knee Arthroplasty Register (SKAR). The part numbers for the femur, tibia and insert (in modular implants) were available in 99.2% of cases. The most common combination used the cemented CR femur against a cemented stemmed baseplate in 50.3% of cases while the same CR femur was used against a cemented pegged baseplate in 8.3% of cases, mainly at two hospitals. In order to make the material more comparable, only patients having osteoarthritis (OA) were included and only TKAs using two types of regular constraint inserts and in which the patella had been left un-resurfaced. Chi-Square test was used to investigate gender distribution in the groups and t-test for the mean age at surgery. Kaplan Meier analysis and the log-rank test were used to evaluate the risk of revision until the end of 2016. A p-value <0.05 was considered statistically significant.Background
Methods
The success of total knee replacement (TKR) surgery can be attributed to improvements in TKR design, instrumentation, and surgical technique. Over a decade ago oxidized zirconium (OxZr) femoral components were introduced as an alternative bearing surface to cobalt-chromium (CoCr), based on strong in-vitro evidence, to improve the longevity of TKR implants. Early reports have demonstrated the clinical success of this material however no long-term comparative studies have demonstrated the superiority of OxZr implants compared to a more traditional CoCr implant. This study aims to compare long-term survivorship and outcomes in OxZr and CoCr femoral components in a single total knee design. We reviewed our institutional database to identify all patients whom underwent a TKA with a posterior stabilized OxZr femoral component with a minimum of 10 years of follow-up. These were then matched to patients whom underwent a TKA with the identical design posterior stabilized CoCr femoral component during the same time period by gender, age and BMI. All patients had their patella resurfaced. All patients were prospectively evaluated preoperatively and postoperatively at 6 weeks, 3 months, 12 months, 2 years and every 1 to 2 years thereafter. Prospectively collected clinical outcome measures included, Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Short-Form 12 (SF-12) and Knee Society clinical rating scores (KSCRS). Charts and radiographs were reviewed to determine the revision rates and survivorship (both all cause and aseptic) at 10 years allowing comparison between the two cohorts. Paired analysis was performed to determine if differences existed in patient reported outcomes.Purpose
Methods
The management of early OA in young patients with joint preservation techniques utilizing cartilage repair remains challenging and a suitable treatment remains unclear. The management of bipolar chondral lesions in the patello-femoral (PF) and in the tibio-femoral (TF) compartment with cartilage repair is especially troublesome. The purpose of this study was to evaluate the clinical outcomes and survivorship after ACI for the treatment of bipolar chondral lesions in the PF and TF compartment. This was an IRB approved, prospectively collected case series, level 4 study. We evaluated 115 patients. 58 patients who had ACI for the treatment of symptomatic bipolar chondral lesions in the PF compartment and 57 in the TF compartment with a minimum 2-year follow up. A single surgeon performed all the surgeries between October 1995 and June 2014. In the PF group, all 58 patients (60 knees; mean age, 36.6 years) were included, and for the TF group one patient did not return for follow-up, 56 patients (58 knees) were included. For the PF group, an average size of the patella and trochlea lesions were 5.6 ± 2.7 cm2 and 4.2 ± 2.8 cm2, respectively. For the TF group, an average of 3.1 lesions per knee were treated, representing a total surface area of 16.1 cm2 (range, 3.2 – 44.5 cm2) per knee. Patients were evaluated with the modified Cincinnati Knee Rating Scale, Visual Analogue Scale, Western Ontario and McMaster Universities Osteoarthritis Index, and the Short Form 36. Patients also answered questions regarding self-rated knee function and satisfaction with the procedure. Standard radiographs were evaluated for progression of OA.Introduction
Methods
Cemented total knee arthroplasty (TKA) remains the gold standard with survivorship above 90% at greater than 10 years postoperatively. However, with younger, heavier, more active patients undergoing TKA at an increasing rate, cementless implants have the appeal of potential for improved implant fixation longevity and decreased rates of aseptic loosening. The cementless implants are more expensive than their cemented counterparts such that implant costs may create a barrier to utilization. However, such comparisons fail to consider the unavoidable additional costs of cementing, including the cost of operating room time, cement and cementing accessories. The purpose of this study is to compare the actual cost of cemented and cementless TKA. The TKA cost calculation included the cost of operative time, implants, cement and cementing accessories. The difference in operative time between cemented and cementless TKA was determined from a previously published study of 100 TKAs performed using a cemented (55) or press fit (45) implant of the same design performed at a single institution by four fellowship trained arthroplasty surgeons. The decision to use cemented or cementless design in these patients was made based on patient bone quality intraoperatively. Operative time was compared between groups using a Student's two-tailed T-test. The cost of operating room time was based on estimates in the recent literature. The cost of cement and cementing accessories was estimated based on publically available market data. The cost of implants was estimated from institutional data for multiple companies.Introduction
Methods
Bilateral total knee arthroplasty (TKA) can be performed under a single-anesthetic (SA) or staged under a two-anesthetic (TA) technique. Recently, our institution began piloting a two-surgeon team SA method for bilateral TKA. The purpose of this study was to compare the inpatient costs and clinical outcomes in the first 90 days after surgery between the team SA, single-surgeon SA, and single-surgeon TA approaches for bilateral TKA. All primary TKA performed from 2007–2017 by the two participating surgeons for each of the 3 groups of interest were identified: team SA (N=42 patients; 84 knees), single-surgeon SA (N=146 patients; 292 knees), single-surgeon TA (N=242 patients; 484 knees). No patients were lost to follow-up.Introduction
Methods
Expanded indications and patient demand have significantly increased the number of TKA performed in young and active patients under age 55. While improved materials have decreased the likelihood of early catastrophic wear, concerns remain with the performance and survivorship of TKA implants in this patient population. Therefore, the purpose this study is to evaluate the clinical outcomes, complications, and implant survivorship of TKAs performed in patients under age 55. We retrospectively reviewed 1194 primary TKA performed for the diagnosis of primary knee osteoarthritis performed at our institution between 2013–2016. There were 291 TKA performed in patients under age 55. Patients were excluded if they had 1) prior history of fracture, 2) renal disease, 3) inflammatory joint disease, and 4) required therapeutic anticoagulation. The primary outcome of interest was rate of revision at 30 days, 1, 2, and 5-year time points. Secondary outcomes included postoperative transfusion rate, calculated blood loss, length of stay(LOS), rate of DVT/PE, readmission and reoperation.Introduction
Materials and Methods
Recent studies of novel healthcare episode payment models, such as the Bundled Payments for Care Improvement (BPCI) initiative, have demonstrated pathways for improving value. However, these models may not provide appropriate payments for patients with significant medical comorbidities or complications. The objective of this study was to identify risk factors for exceeding our institution's target payment, the so-called “bundle busters.” After receiving an exemption from the Institutional Review Board, we queried our institutional data warehouse for all patients (n=412) that underwent total joint arthroplasty (TJA) of the hip (n=192), knee (n=207), or ankle (n=13), and qualified for our institution's bundled payments model during the study time period (July 2015 – May 2017). Patients with medical conditions that were not well controlled or were potentially optimizable were all sent for preoperative medical optimization prior to surgery. For each 90-day episode, patient characteristics, medical comorbidities, perioperative data, and payments from the Centers for Medicare and Medicaid Services (CMS) were obtained. Episodes where Medicare payments exceeded the target payment were considered “busters”. The busters were older, and had higher comorbidity scores (all, p<0.01). Variables were summarized using descriptive statistics and risk ratios were calculated using a modified Poisson regression analysis.Introduction
Methods
Morbid obesity (BMI>40) is a significant risk factor for complications following total joint arthroplasty (TJA). As such many have a restrictive practice of withholding elective primary TJA in the morbidly obese. The purpose of this study was to observe the implications of this practice. From 2012 to 2014, 289 patients with morbid obesity and end-stage OA of the hip or knee were prospectively followed. At initial visit, patients were given a packet on risks of TJA in the morbidly obese and referral information to a weight loss clinic. Patients were contacted at 6, 12, 18 and 24 months from initial visit for PROs, and BMI changes. The average age of patients was 56 (26.7–79.1) there were 218 females and 71 males.Introduction
Methods
Unicompartmental knee arthroplasty (UKA) offers significant advantages over total knee arthroplasty (TKA) but is reported to have higher revision rates in joint registries. In both the New Zealand and the UK national registry the revision rate of cementless UKR is less than cementless. It is not clear whether this is because the cementless is better or because more experienced surgeons, who tend to get better results are using cementless. We aim to use registry data to compare cemented and cementless UKA outcomes, matching for surgical experience and other factors. We performed a retrospective observational study using National Joint Registry (NJR) data on 10,836 propensity matched Oxford UKAs (5418 cemented and 5418 cementless) between 2004 and 2015. Logistic regression was utilized to calculate propensity scores to match the cemented and cementless groups for multiple confounders using a one to one ratio. Standardised mean differences were used before and after matching to assess for any covariate imbalances. The outcomes studied were implant survival, reasons for revision and patient survival. The endpoint for implant survival was revision surgery (any component removal or exchange). Cumulative patient and implant survival rates were determined using the Kaplan-Meier method. Patients not undergoing revision or death were censored on the study end date. The study endpoints implant and patient survival were compared between cemented and cementless groups using Cox regression models with a robust variance estimator.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 the reliability of robotic assisted UKA over manual UKA in component placement and executing a soft-tissue tensioning plan. The purpose of this multicenter study was to determine the correlation between 3D component positioning and soft-tissue tensioning with short-term clinical results following robotic assisted medial UKA. Between 2013 and 2016, 349 patients (381 knees) underwent robotic assisted fixed bearing metal backed medial UKAs at two centres. Follow-up was performed at 12 months minimum. Pre- and post-operatively, patients were administered Knee Injury and Osteoarthritis Score (KOOS), Forgotten Joint Score 12 (FJS), and Short-Form summary scale (SF-12) surveys. Clinical results for every score were stratified as ‘excellent’, ‘mild’ and ‘insufficient’. Post-operative complications were recorded. Failure mechanisms, reoperations and post-operative knee pain were also assessed. Intra-operative robotic data relative to femoral and tibial component placement in the coronal, sagittal and horizontal plane, as well as femoro-tibial gaps at different knee flexion angles were also collected.Introduction
Methods
Existing studies report more accurate implant placement with robotic-assisted unicompartmental knee arthroplasty (UKA); however, surgeon experience has not always been accounted for. The purpose of this study was to compare the accuracy of an experienced, high-volume surgeon to published data on robotic-assisted UKA tibial component alignment. One hundred thirty-one consecutive manual UKAs performed by a single surgeon using a cemented, fixed bearing implant were radiographically reviewed by an independent reviewer to avoid surgeon bias. Native and tibial implant slope and coronal alignment were measured on pre- and postoperative lateral and anteroposterior radiographs, respectively. Manual targets were set within 2° of native tibial slope and 0 to 2° varus tibial component alignment. Deviations from target were calculated as root mean square (RMS) errors and were compared to robotic-assisted UKA data.Introduction
Methods
Over the past few decades, opioid abuse has become a major threat to public health. In 2013 alone, enough opioid prescriptions were written in the United States for every American adult to have their own bottle of pills. Since then, opioid prescribing rates and opioid related deaths have continued to grow, with over 46 people dying on average each day from prescription opioid overdoses in 2016. Orthopaedic surgeons are among the top 5 specialties in the number of opioid prescriptions written. For many common surgeries, such as total knee arthroplasty (TKA), post-discharge prescriptions are based on prescriber habits and opinion. There exists limited data-driven protocols to guide post-operative opioid prescribing practices. The purpose of this prospective study was to determine the average postoperative opioid consumption in patients undergoing primary TKA using a novel mobile text messaging platform. We hypothesized that majority of patients undergoing TKA do not properly dispose of left over pills after surgery. 95 patients undergoing primary unilateral TKA with one of nine arthroplasty surgeons at a single orthopaedic specialty hospital were prospectively enrolled. Daily pain levels and opioid consumption, and quantity and disposal patterns for left over medications were collected for six weeks following surgery using a novel mobile phone text messaging system. This system automatically queried patients twice a day, storing responses on a secure third-party host that investigators monitored and used to generate data reports in real-time.Introduction
Methods
Lateral partial knee replacement is indicated as an alternative to total knee replacement for isolated end stage lateral compartment degenerative joint disease. The purpose of this study is to report the surgical technique and clinical results of a large series of lateral partial knee replacements from two institutions. A retrospective review identified 205 lateral unicompartmental arthroplasty procedures performed in two practices over a six-year period (Aug 2011 – June 2017). Patients indicated for surgery met specific preoperative clinical and radiographic criteria confirming lateral compartment arthritic disease with a correctable deformity, intact full-thickness medial cartilage, competent anterior cruciate ligament, and minimal disease in the patellofemoral compartment. A single cemented fixed bearing tibial component design was used in all cases specifically designed for lateral compartment anatomy.Intro/Purpose
Methods
Postoperative pain is a concern for patients undergoing Total Knee Arthroplasty (TKA) and plays an important role in opioid consumption, length of stay, and postoperative function. The purpose of this study was to compare outcomes in patients who underwent primary TKA comparing femoral and sciatic (F+S) combination motor nerve block versus an adductor canal and the interspace between the popliteal artery and the capsule of the posterior knee (ACB+IPACK) combination sensory nerve block. 100 consecutive primary TKA cases performed by a single surgeon using the same surgical approach and implant design were reviewed. The first 50 patients received F+S nerve blocks and the second 50 received ACB+IPACK blocks preoperatively. Both groups also received total intravenous anesthesia (TIVA). Differences in opioid requirements, length of stay (LOS), distance walked, Western Ontario & McMasters University Osteoarthritis Index (WOMAC), Knee Society (KSS) function scores, Visual Analog Scores (VAS) for pain at rest and with activity, and postoperative complications were analyzed. There were no differences in the groups with respect to age, sex or BMI.Introduction
Methods
In recent years, online patient portals have been developed to offer the potential of an enhanced recovery experience. By offering videos, communication tools and patient-reported outcomes collection, online portals encourage patient's engagement in their care. In the total joint arthroplasty population, portals may also offer online physical therapy, allowing TJA patients to reach functional goals while reducing costs. Although technology may offer the potential of an enhanced recovery experience, disparities may exist between the comfort level of use and communication preferences of different patient populations. Our study aimed to analyze the utilization of an internet based patient portal, and quantify the impact of usage on patient reported outcome measures. 4,458 patients who underwent TJA across 8 major academic centers within one healthcare system were analyzed. Patients who scheduled surgery were registered for the online portal by the surgical coordinator. Upon registration, patients opt-in by signing a license agreement, and data is collected on their utilization of the portal including logins, exercise and educational videos watched, messages sent and PROs completed. Age was compared to utilization, opt-in rates, total videos watched, and messages sent. Two separate patient cohorts were identified to distinguish between active and non-active users. Anyone who opted-in and viewed over 5 preoperative videos or had at least 5 preoperative logins were considered active users. Patients’ postoperative KOOS-JR and HOOS-JR score improvements from baseline were compared between the active vs. non-active groups.Introduction
Methods
Closed suction intraarticular drain (CSD) use after total knee arthroplasty (TKA) has been studied with regards to wound healing and range of motion, however, no data exist on how CSD use impacts knee joint effusion and quadriceps strength. The primary purpose of this study was to determine whether CSD use influences recovery of quadriceps strength. Secondary outcomes examined effects of CSD on intraarticular effusion, lower limb swelling, knee range of motion (ROM), pain and wound healing complications. Twenty-nine patients undergoing same-day bilateral TKA were enrolled in a prospective, randomized blinded study. Subjects were randomized to receive a CSD on one lower extremity while the contralateral limb had the use of a subcutaneous drain (SCDRN) without the use of suction. Isometric quadriceps strength was collected as the primary outcome. Secondary outcomes consisted of quadriceps muscle activation, intraarticular effusion measured via ultrasound, lower extremity swelling measured with bioelectrical impendence, lower extremity girth, ROM, and pain. Outcomes were assessed preoperatively and postoperatively at day 2, 2 and 6 weeks and 3 months. Differences in limbs were determined using paired t-tests or Wilcoxon signed rank tests.Introduction
Methods
Total Knee Arthroplasty (TKA) in high risk patients may result in numerous post-operative complications that may ultimately lead to above knee amputation (AKA). There is a paucity of literature regarding AKA in patients with prior TKA. We sought to characterize the factors leading to AKA, as well as patient functional and clinical outcomes post-operatively, with the hypothesis that minimal activity would be achieved. This is a multicenter retrospective review for patient identification, with prospective telephone survey completion for assessment of functional status. All patients from January 2001 to December 2015 with AKA and prior TKA at two academic centers were included for possible survey enrollment. Demographic information and medical comorbidities were collected, in addition to perioperative and post-operative mortality data. A 23-item survey was provided to all available patients and analyzed for patient functional status.Introduction
Methods
At a time when many surgeons are reluctant to perform a unilateral TKA in the obese patient, little is written on the safety and efficacy of bilateral simultaneous TKA in this same patient population. While these potential benefits are attractive to patients, surgeons may be hesitant to perform bilateral TKA due to the greater physical demand placed on the patient, and a potential increase in postoperative complication. The primary aim of this study was to analyze the impact of obesity on clinical outcomes and complication rates of patients undergoing bilateral TKA under one anesthetic. The clinical outcomes of 133 patients (266 knees) who underwent bilateral TKA between 2013 and 2016 were reviewed. The procedures were performed by three separate surgeons across three major academic institutions. ASA scores, tourniquet time, operative time, blood loss, length of stay, readmission, and postoperative complications were compared between different BMI categories of less than 30 kg/ m2, 30–34.99 kg/ m2, 35–39.99 kg/ m2and above 40 kg/ m2Introduction
Materials and Methods
With the rising utilization of total joint arthroplasty, the role of simultaneous-bilateral surgery has expanding impact. The purpose of this study is to examine the risk of perioperative complications for this approach in total knee arthroplasty to inform shared decision making. We used nation-wide linked discharge data from the Hospital Cost and Utilization Project from 2005–2014 comparing outcomes of simultaneous-bilateral and staged-bilateral total knee arthroplasties (TKAs). Hierarchical logistic regression analysis was used to compare mortality within 30 days, 90 days and 1 year, perioperative risks within 30–60 days, and infection and mechanical complications within 1 year.Introduction
Methods
Robotic-arm total knee arthroplasty (RTKA) was developed to potentially improve accuracy of bone cuts, component alignment, soft tissue balance, and patient outcomes. There is a paucity of data demonstrating that RTKA is superior to conventional total knee arthroplasty (CTKA) in terms of any of these metrics. This prospective comparative multicenter study was designed with these purposes in mind. Patients were enrolled between June 1st, 2016 and March 31st, 2018 in a prospective, non-randomized, open-label, multicenter, consecutive comparative cohort study comparing RTKA and CTKA. Only patients who satisfied the following inclusion criteria were included: body mass index (BMI) ≤ 40kg/m2, primary unilateral TKA procedure, at least 18 years of age, and no joint infection. The following data were collected for analysis:
Preoperative data on component size prediction from CT scans Intraoperative data on bone resection levels and joint line maintenance Functional activity scores, patient-reported symptoms, satisfaction and expectation scores using The New Knee Society Scoring System Radiographic results, specifically coronal alignmentIntroduction
Methods
The utilization of lymphocyte transformation testing (LTT) has increased for diagnosing metal sensitivity associated with TKA, but its validity for the diagnosis of TKA failure due to an immune reaction has not been established. We performed a retrospective study of 27 well-fixed, aseptic primary TKAs with persistent pain and/or stiffness, revised by a single, experienced surgeon for suspected metal allergy to nickel based on a positive LTT. Periprosthetic tissue samples obtained at the time of revision surgery were scored using the aseptic lymphocytic vasculitis-associated lesion (ALVAL) scoring system.Introduction
Methods
There is no literature regarding the risk of a patient developing PJI after primary TKA if the patient has previously experienced PJI of a TKA or THA in another joint. The goal of this study was to compare the risk of PJI of primary TKA in this patient population compared to matched controls. We retrospectively reviewed 95 patients (102 primary TKAs) from 2000–2014 with a history of a TKA or THA PJI in another joint. Mean age was 69 years; mean BMI was 36 kg/m2. 27% high-risk patients were on chronic antibiotic suppression. Mean follow-up was 6 years. We 1:3 matched (to age, sex, BMI, and surgical year) these to 306 primary TKAs performed in patients with a THA or TKA of another joint without a subsequent PJI. Competing risk with death was used for statistical analysis. Multivariate analysis was utilized to evaluate risk factors for PJI in the study cohort.Introduction
Methods
Despite several preventive strategies, periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) is still a devastating complication. Early diagnosis and appropriate treatment are crucial to achieve successful infection control, but challenging since there is no test with 100% sensitivity and 100%. Therefore, several national and international guidelines include synovial analysis of joint aspirates as important diagnostic criteria, but cut-off levels for synovial cell count (CC) and polymorphonuclear (granulocyte) percentage (PMN%) are still debatable. The current investigation was performed to analyze the overall accuracy and optimal cut-off of synovial CC and PMN% following total knee (TKA) and total hip arthroplasty (THA). Between October 2012 and June 2017, all patients with painful TKA or THA, who underwent joint aspiration before revision arthroplasty were included in this retrospective study. From aspirated synovial fluid, leukocyte esterase activity, leukocyte CC and PMN% were determined, and specimens were sent for bacterial culture. A total of 524 preoperative joint aspirations (255 hips, 269 knees) were enrolled for final analysis. For 337 patients, the synovial CC and PMN% could be measured by the laboratory. From those patients, 203 patients were scheduled for aseptic revision, and 134 patients for septic revision arthroplasty according to the MSIS criteria for PJI. Specificity (SP), sensitivity (SE), positive predictive value (PPV), negative predictive and overall accuracy were measured for CC and PMN%. The optimum cut-off value was calculated by the ROC and the value giving the AUC, achieving the best possible level of sensitivity and specificity.Introduction
Methods
Implant malalignment is an important predictor of prosthetic failure following total knee arthroplasty (TKA). The purpose of this study was to determine the incidence of outliers for common alignment targets and the impact of surgeon volume and experience on the accuracy of implant alignment with current generation manual instrumentation. This study was a retrospective, multi-center, radiographic analysis of 1675 consecutive primary uncomplicated TKAs from seven surgeons at three academic and state-funded centers in the US and UK. Surgeons were categorized as “high-volume” (≥50 TKAs/year) and “high-experience” (≥5 years post-fellowship). Femorotibial, tibial varus/valgus, and posterior tibial slope angles were digitally measured using postoperative radiographs. Femorotibial (<2° or >8° valgus), tibial (> ±3° deviation from the neutral axis), and tibial slope (<0° or >7° of flexion for cruciate retaining, <0° or >5° of flexion for posterior stabilized) angle outliers were identified. The proportion of outliers among surgeons in each subgroup was compared.Introduction
Methods
Tibial tuberosity and trochlear groove (TT-TG) distance has been investigated for the patients with primary patellofemoral subluxation/dislocation. To date, TT-TG distance after TKA has not been evaluated, and the effect of postoperative TT-TG distance on patellar tracking is unknown. The purpose of the current study was to investigate the effect of TT-TG distance and rotational position of the femoral and tibial components on patellar tilt after TKA. Consecutive 115 knees for the diagnosis of osteoarthritis were included in the current study. TKA was performed using posterior cruciate ligament sacrificed prosthesis. A total of 17 men and 96 women with an average age of 75.3 years were included at the time of the surgery. Computed tomography (CT) was taken after TKA in full extension. Postoperative TT-TG distance was measured as a reference of surgical epicondylar axis (SEA) of the femur. Patellar tilt was defined as the angle of the patellar component relative to SEA. Femoral and tibial component rotation was measured as the angle relative to SEA and tibial antero-posterior (AP) axis. Tibial AP axis was defined as the line connecting medial one-third of the tibial tuberosity and center of medial-lateral width. Pearson correlation coefficients were calculated to determine the correlations between patellar tilt and TT-TG distance and between patellar tilt and femoral and tibial component rotation.Introduction
Methods
Tibial component malrotation is associated with pain, stiffness and altered patellofemoral kinematics in total knee arthroplasty (TKA). However, accurately measuring tibial component rotation following TKA is difficult. Proposed protocols utilizing computed tomography (CT) are not well validated and can be time consuming. This study aimed to; 1) Validate and compare the reproducibility of the Berger (2D-CT) and Mayo (3D-CT) protocols; 2) Validate a simple, and potentially rapid screening measurement using an anatomical distance on 2D axial CT- the Centre of Tibial Tray to Tibial Tubercle (CTTT) distance. Rotational alignment of 70 TKA patients were evaluated by 3 independent observers using the Berger, and Mayo protocols, which have been previously described, and a new CTTT protocol (Figure 1). The inter and intra-rater interclass correlation coefficients (ICC's), mean difference between measurements and the mean measurement times were calculated. Linear regression analysis was performed to give a coefficient of determination (R2).Introduction
Methods
This study compares the PFC total knee arthroplasty (TKA) system in a prospective randomized control trial (RCT) of the mobile-bearing rotating-platform (RP) TKA against the fixed-bearing (FB) TKA. This is the largest RCT with the longest follow-up where cruciate-retaining PFC total knee arthroplasties are compared in a non-bilateral TKA study. A total of 167 patients (190 knees with 23 bilateral cases), were recruited prospectively and randomly assigned, with 91 knees receiving the RP and 99 knees receiving FB. The mean age was 65.5 years (48 to 82), the mean body mass index (BMI) was 29.7 kg/m2 (20 to 52) and 73 patients were female. The Knee Society Score (KSS), Knee Society Functional Score (KSFS), Oxford Knee Score (OKS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), and 12-Item Short-Form Health Survey Physical and Mental Component Scores (SF-12 PCS, SF-12 MCS) were gathered and recorded preoperatively, at five-years’ follow-up, and at ten years’ follow-up. Additionally, Knee Injury and Osteoarthritis Outcome Scores (KOOS) were collected at five- and ten-year follow-ups. The prevalence of radiolucent lines (RL) on radiographs and implant survival were recorded at five- and ten-year follow-ups.Aims
Patients and Methods
Despite the demonstrated success of total knee arthroplasty (TKA) and higher rates of arthritis and disability from arthritis among minorities, these populations utilize TKA at lower rates than non-Hispanic white patients in the United States. In addition, women present for TKA with more advanced disease prior to TKA than their male counterparts. In order to explore potential reasons for this, we examined the relationship between race, gender, and pre-operative expectations on postoperative outcomes among patients undergoing TKA. 134 patients scheduled for primary unilateral TKA secondary to moderate to severe osteoarthritis were enrolled in this two-institution prospective study. All patient demographics were collected and recorded in an electronic data registry. In addition, patient reported outcome (PRO) questionnaires, including the Knee Injury and Osteoarthritis Outcome Score (KOOS), HSS Patient Expectation Questionnaire, Social Support Survey, Pain Catastrophizing Scale, Visual Analogue Pain Scale (VAS), Geriatric Depression Scale and European Quality (EQ) of Life 5-Dimensions with EQ VAS were prospectively collected at 4 time points (baseline, 4–8 weeks, 9–14 months, 20–26 months postoperative). Statistical analysis was then conducted among patients of different gender and ethnic background to assess for the effect of these demographic variables on patient expectations and outcomes.Introduction
Methods
This study was designed to evaluate the effect of discharge timing on 30-day major and minor complications in patients undergoing total knee arthroplasty (TKA) while adjusting for other variables. Patients 18 years and older undergoing TKA between the years of 2005 and 2016 were identified from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP). Patients whose length of stay (LOS) was >4 days were excluded. Patient demographics, anesthesia type, length of operation and hospital stay, as well as 30-day major and minor complications were collected from the database. Chi square tests were utilized to compare the unadjusted rates of complications between patients whose LOS was 0, 1, 2, and 3–4 days. Multivariable regression was utilized to evaluate the effect of LOS on complication rates, while adjusting for age, American Society of Anesthesiologist (ASA) class, type of anaesthesia, functional status, comorbidities, sex, steroid/immunosuppressant use, body mass index (BMI), diabetes, length of operation and smoking status.Introduction
Methods
The causes of revision total knee replacement are varied. There is a subset of these revision cases (poly wear and some cases of instability for example) where the ability to retain the metal femoral and tibial components and replacing just the polyethylene is an appealing option. We report on a series of RTKR where only the poly insert was replaced and the patients were followed for a minimum of ten years. Our study group consisted of 64 consecutive non infected RTKR patients who underwent a revision of the polyethylene alone between 1998 and 2006. All patients had been treated originally with the same cemented, CR, patella resurfaced primary TKR. Reasons for revision were 51 poly wear and/or osteolysis, 7 instability, and 6 other. The average time from the primary to the revision surgery was 9.1 years (range 2.2 to 16.1 years). All patients had an isolated poly liner change. No femurs or tibial trays were revised. Average age of the cohort at revision was 72.2 (range 48 to 88). Average BMI was 31.9 (range 23.6 to 43.9). There were 36 female patients. Of the group, 42 were ASA 1 or 2 and 22 were ASA 3. Pre-op alignment averaged 6.0 (range 2 varus to 8 valgus). Patients were followed for a minimum of 10 years (range 10 to 19 years).Introduction
Materials and Methods
Successful total knee arthroplasty (TKA) is predicated on accurate bony resection, mechanical alignment and component positioning. An active robotic TKA system is designed to achieve reliable and accurate bony resection based upon a preoperatively developed surgical plan. Surgical resections are executed intra-operatively according to this pre-operative plan. The goal of this study was to determine the accuracy of final implant positioning and alignment using this active robotic device, as well as its early clinical outcomes. An FDA prospective study under investigational device exemption was conducted from 2017–2018. Pre-operative CT scans were used to create a pre-operative plan using the TSolution One? Surgical System (THINK Surgical, Inc). TKA was performed using a standard approach, with planned and robotically executed femoral and tibial resections. Subjects completed 3-month follow-up with post-operative CT scans. A validated method was used to compare pre- and post-operative CT scans to determine differences between planned and achieved implant position. Femoral and tibial component sizing, and mean differences in implant position and alignment were compared. Short Form 12 Physical (PCS) and Mental Component Summary (MCS) scores as well as Knee Society (Objective and Functional) scores at 12 weeks post-operatively were compared with pre-operative scores. Paired-sample t-tests were used for comparisons.Objectives
Materials and Methods
The success of total knee arthroplasty (TKA) necessitates precise osteotomies and soft tissue balancing to realign the lower extremity to a neutral mechanical axis. While technological advances have facilitated precise osteotomies, soft tissue balancing has traditionally relied mostly on surgeons’ subjective and variable tactile feedback. As soft tissue imbalance accounts for 35% of early TKA revisions in North America, we aimed to compare outcomes when TKA was balanced free-hand versus a sensor-guided balancing device (VERASENSE, OrthoSensor, Inc (Dania, FL)). In a randomized-controlled fashion, patients underwent primary TKA soft tissue balancing either free-hand or with VERASENSE (Orthosensor Inc, Dania FL) at our institution beginning January 2018. With VERASENSE, soft-tissue balancing is considered when the pressure difference between the medial and lateral knee compartments was less than 15 pounds. Data regarding patient-reported outcomes, knee range of motion (ROM), pain level, opioid consumption, inpatient ambulation distance, length of stay (LOS), and incidence of arthrofibrosis was collected and analyzed in a two-year minimum follow-up and target patient goal of 120 patients.Introduction
Methods
Cementless total knees were historically associated with early failure. These failures, likely associated with implant design, made cemented total knee arthroplasty (TKA) the “gold standard”. Manufacturers have introduced newer uncemented technologies that provide good initial stability and utilize a highly-porous substrates for bony in-growth. Outcome data on these implants has been limited. In addition, these implants typically have a price premium which makes them difficult to use in the setting of cost containment and in at risk 90-day bundles. Our purpose was to compare 90-day outcomes of a new uncemented implant with those of a comparable cemented implant from the same manufacturer. We hypothesized that the implants would have equivalent 90-day clinical and economic outcomes. Ninety-day clinical and economic outcomes for 252 patients with prospectively collected data from the Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI) database were reviewed. Ninety-day outcomes were compared between uncemented knees and an age-matched group of cemented knees (Triathlon cemented vs uncemented Triathalon-tritanium, Stryker Orthopedics, Mahwah, NJ, USA). Both cruciate retaining and posterior stabilized designs were included. MARCQI data: demographics, co-morbidities, length of stay, complications, emergency department visits, discharge disposition, and readmissions were reviewed. Financial data provided by the hospital's finance department was used for economic comparisons. Fischer's test was done to assess categorical data and a student's t-test was used to compare numerical data.Introduction
Methods
Hip and knee replacements are being performed at increasing rates and currently account for one of the largest procedure expenditures in the Medicare budget. Outcomes of total knee replacement (TKR) depend on surgeon, patient and implant factors. The impact that the specific implants might have on patient-reported outcomes is unknown. The primary purpose of this study was to evaluate the patient-reported functional outcomes and satisfaction after primary total knee arthroplasty in patients with osteoarthritis who underwent TKR using five different brands of posterior-stabilized implants. Specifically, the aim was to evaluate for any difference in patient-reported outcomes based on implant brand used. The hypothesis was that there would be no difference in functional outcome that could be attributed to the implant used in primary TKR. Using our institution's total joint arthroplasty registry, we identified 4,135 patients who underwent total knee replacement (TKR) using one of the five most common implant brands used at our institution. These included Biomet Vanguard (N=211 patients), Depuy/Johnson&Johnson Sigma (N=221), Exactech OptetrakLogic (N=1,507), Smith & Nephew Genesis II (N=1,414), and Zimmer NexGen (N=779). Only posterior-stabilized primary TKRs in patients with osteoarthritis were included. Patients were evaluated preoperatively using the Knee Osteoarthritis Outcomes Score (KOOS), Lower Extremity Activity Scale (LEAS), and Short Form-12 (SF-12). Demographics including age, body mass index (BMI), Charleston Comorbidity Index (CCI), ASA physical status classification, sex, and smoking status were collected. Postoperatively, 2-year KOOS, LEAS, SF-12, and satisfaction scores were compared between implant groups.Introduction
Methods
Multimodal pain management strategies are now commonplace in perioperative management of total knee arthroplasty (TKA), although controversy remains regarding the role of adductor canal blocks (ACB) in this algorithm. Proposed benefits include theoretical decreased role of perioperative narcotic pain medication, improved function with physical therapy postoperatively, shorter duration of hospital stay and improved patient satisfaction. Those opposed cite increased cost and risk of complications including inadvertent motor blockade. The purpose of this study was to independently evaluate the effect of adductor canal block on short-term post-operative outcomes including (1) length of stay (LOS), (2) post-operative narcotic utilization, and (3) function with physical therapy in the era of modern TKA. Our institutional database was utilized to retrospectively identify a cohort of consecutive patients from January 2014-January 2018 who had undergone unilateral primary TKA with a single surgeon utilizing a preoperative single-shot ACB in addition to a standardized multimodal pain regimen versus those that only received the same multimodal pain regimen (no-ACB). The primary reason that a patient did not receive a preoperative block was lack of availability of the block team The time period of interest was selected based on the implementation of our current pain protocols. The multimodal pain regimen consists of: preoperative Tylenol, a periarticular injection intraoperatively including 0.5% Marcaine and Toradol, IV Toradol postoperatively, Percocet, Celebrex and IV narcotic medication for breakthrough pain. These 2 groups were compared utilizing independent sample T-tests with primary endpoints of interest being LOS (in total hours and as %day 1 discharges (%POD1)), distance ambulated with inpatient therapy on postoperative day 1, and inpatient narcotic use as measured in morphine equivalents per hour. A sub-cohort of patients with adductor canal block was then selected based on time of surgery to control for time of discharge and hours in the hospital to isolate the effect of the block.Introduction
Methods
Extraction of implants due to periprosthetic infection (PJI) following complex revision total knee arthroplasty (rTKA) with extensive hardware can be a daunting undertaking for surgeon and patient alike. We question whether irrigation and debridement (I&D) has a role in this difficult situation with respect to infection control, reoperation, and function. rTKAs for PJI from 2005–2016 were reviewed. Extensive hardware was defined as: metaphyseal cone/sleeve fixation, distal femoral replacement, periprosthetic fracture hardware, or stems >75mm. Cases were categorized by treatment (I&D or 2-stage exchange).Introduction
Methods
Robotic assisted Total Knee Arthroplasty (rTKA), provides surgeons with preoperative planning and real-time data allowing for continuous assessment of ligamentous tension and range-of-motion. Using this technology, soft tissue protection, reduced early post-operative pain and improved patient satisfaction have been shown. These advances have the potential to enhance surgical outcomes and may also reduce episode-of-care (EOC) costs for patients, payers, and hospitals. The purpose of this study was to compare robotic assisted vs. manual total knee arthroplasty: 1) 90-day episode-of-care (EOC) costs; 2) index costs; 3) lengths-of-stay (LOS); 4) discharge disposition; and 5) readmission rates. TKA procedures were identified using the Medicare 100% Standard Analytic Files including; Inpatient, Outpatient, Skilled Nursing (SNF) and Home Health. Members included patients with rTKA or manual TKA (mTKA) between 1/1/2016-3/31/2017. To account for potential baseline differences, propensity score matching (PSM) was performed in a 1-to-5 ratio, robotic to manual based on age, sex, race, geographic division, and comorbidities. After PSM, 519 rTKA and 2,595 mTKA were identified and included for analysis. Ninety-day episode-of-care cost, index cost, LOS, discharge disposition and readmission rates were assessed.Introduction
Methods
Pressure to control health care costs may limit the ability of new implants to enter the market. Customized individually made (CIM) knee implants are produced from CT scans of each patient and may result in improved clinical outcomes based on early data showing less blood loss, reduced bone resection, and better implant function and alignment. Limited economic evidence suggests that the use of CIM technology may result in cost savings, particularly when post-discharge expenses are included. The purpose of this study was to evaluate real-world cost data to determine episode spending in a Medicare population receiving either CIM or off-the-shelf (OTS) implants. The Yale Center for Musculoskeletal Care and Baker Tilly Healthcare Management reviewed episode expenditures among Medicare beneficiaries who received CIM and OTS implants for TKA between 01/01/2015 and 12/31/2015. Episode costs included the pre-operative CT scan, index TKA procedure, and 12-month post-index spending for inpatient (IP), outpatient (OP), emergency room (ER), skilled nursing facility (SNF), and home health (HH) services. CIM patients were identified through a matching process utilizing de-identified patient demographic and procedural information and the presence of a CT scan 28–365 days before index. OTS patients included those without a CT scan within one year of index. CIM and OTS cohorts were propensity matched to produce comparable cohorts at a one-to-five ratio based on age range, gender, race, geographical location, and comorbidities. Average expenditure was used to calculate one-year costs of care differences between the CIM and the OTS technologies. A Generalized Linear Model (GLM) and two-part model (logistics and GLM) were used to test statistical significance.Introduction
Methods
Pseudotumor or high grade ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) development around total hip replacements secondary to local metal debris generation – especially in the setting of metal-on-metal bearings – is a well-recognised histopathologic phenomenon. Recent work has suggested a strong genetic correlation with an individual's risk of such lesion development following metal exposure. Emerging data have highlighted a similar potential concern around total knee replacements (TKRs), particularly with increasing construct modularity. To date, the body-of-knowledge pertaining to TKR-associated ALVALs has largely been limited to individual case reports or small retrospective case series’, with no large-scale investigation looking at this potential complication. This study sought to establish the preliminary prevalence of pseudotumor or high grade ALVAL formation seen at the revision of primary TKRs and to establish the correlation between histologic ALVAL grade and patient-reported functional outcomes. Findings of 1263 consecutive patients undergoing revision knee surgery, at a high-volume referral center, were reviewed. 161 cases of active infection were excluded. Complete histopathology reports were subsequently available for 321 (29.1%) non-infective cases. Each case was independently histologically-classified using a previously validated scoring system reflecting ALVAL grade. Post-operative patient-reported outcomes measures (PROMs) were available for 134 patients (41.7%), allowing direct correlation between functional performance and the established histopathology results.Background
Methods
The demands placed upon joint surgeons are perhaps greatest when treating the revision arthroplasty patient, who present with complications demanding skill in diagnosis and evaluation, interpersonal communication and the technical aspects of the revision procedure. However, little information exists identifying which specific tasks in revision arthroplasty are most difficult for surgeons to master, and whether the greatest challenges arise from clinical, cognitive or technical facets of patient treatment. This study was undertaken to identify which tasks associated with revision total knee replacement (TKR) are perceived as most challenging to young surgeons and trainees to guide future efforts in surgical training and curriculum development. We developed an online survey instrument consisting of 69 items encompassing pre-operative, intraoperative, and post-operative tasks that preliminary studies identified as the essential components of revision TKR. These tasks encompassed 4 domains: clinical decision-making skills (n=9), interpersonal assessment and communication (n=7), surgical decision-making (n=35) and procedural surgical tasks (n=18). Respondents rated the difficulty of each item on a 5-level Likert scale, with an ordinal score ranging from 1 (“very easy”) to 5 (“very difficult”. The survey instrument was administered to a cohort of 109 US surgeons: 31 trainees enrolled in a joint fellowship program (Fellows) and 78 surgeons who had graduated from a joint fellowship program within the previous 10 years (Joint Surgeons). Using appropriate parametric and non-parametric tests, the responses were analyzed to examine the variation of reported difficulty of each of the 69 items, in addition to the nature of the task (cognitive, surgical, clinical and interpersonal), and differences between Fellows and Surgeons.Introduction
Methods
Total knee arthroplasty (TKA) is a successful treatment for degenerative end stage knee arthritis. Younger patients who undergo TKA may face multiple revisions during their lifetime due to aseptic loosening, infection, and instability. The purpose of this study was to compare the early complication rates and revision free survivorship between age groups undergoing TKA in a nationwide database. The PearlDiver national insurance database was queried from 2007–2015 for all patients who underwent primary TKA. Kaplan-Meier Curve survival analysis and log rank test were performed to evaluate revision rates between age groups (<40, 40–49, 50–59, 60–69, 70–79, 80–89, and ≥90 years). Complication rates were compared to rates in the age 60–79 group using multiple logistic regressions controlling for baseline demographics and comorbidities.Introduction
Methods
Infection remains as one of the major challenges of total joint surgery. One-stage irrigation, debridement and reimplantation or two-stage revision surgery with a temporary implantation of antibiotic eluting bone cement spacer followed by reimplantation are two methods often used to treat infected patients with mixed outcomes. Like bone cement, ultra-high molecular weight polyethylene (UHMWPE) can also be used as a carrier for antibiotics. Recently, we demonstrated that vancomycin and rifampin can be successfully delivered from UHMWPE implants at therapeutic levels to eradicate Staphylococcus aureus biofilm in a lupine animal model. There are regulatory challenges in translating these types of combination devices in to clinical use. One approach is to follow a stepwise strategy, with the first step of seeking clearance for a temporary UHMWPE spacer containing gentamicin sulfate. In this study, we explored the effect of gentamicin sulfate (GS) content in UHMWPE on GS elution rate and antimicrobial activity against methicillin-sensitive S. aureus(MSSA). We also assessed the effect of spacer fabrication on the activity of gentamicin sulfate. We prepared and consolidated UHMWPE/GS blends in varying concentrations. After consolidation, we fabricated test samples with surface area (350mm2) to volume (300mm3) ratio of 1.2 for elution in 1.5ml phosphate buffered saline at body temperature for up to six months and quantified eluted GS content using liquid chromatography – mass spectrometry (LCMS). We assessed the antibacterial activity of the obtained samples in vitro against various concentrations of MSSA (103–106 CFU/ml). Furthermore, we quantified the probability of bacterial colonization of UHMWPE impregnated with GS compared to GS containing bone cement. We assessed any detectable changes in activity of eluted GS caused by spacer fabrication by screening m/z peaks of GS isomers in mass spectra obtained from LC-MS. Gentamicin sulfate activity was not compromised by the elevated temperature and pressure used during spacer fabrication. Elution rate of GS increased with increasing GS content in the blends studied. At comparable elution rates, the GS-loaded UHMWPE was either equivalent or better in terms of antibacterial and anticolonization properties when compared with gentamicin containing bone cement. GS-impregnated UHMWPE is a promising material for temporary spacers.
Patient reported outcome measures (PROMs) are recognized as crucial in evaluating the outcome of total knee arthroplasty (TKA). New Knee Society Score (NKSS), introduced in 2011, is reported to be an effective, such outcome measure. Forgotten Joint score (FJS), introduced in 2012, has been validated but has only a few studies in literature reporting upon it. In a normal population without arthritis, the FJS is reported to be between 50–95, a higher score representing better status. Our aim was to determine 1) the FJS at 1-year post TKA, distributing patients in 2 groups of FJS less than/more than 50; assessing its ceiling and floor effect 2) the influence of age, sex, BMI, diabetes, thyroid, type of deformity, pre/post-operative flexion and 3) to compare and correlate FJS with NKSS and its sub-scores - Objective knee score(OKS) and Subjective knee score(SKS). We enrolled 181 patients (222 knees), who had primary TKA performed by the same surgeon at Lilavati Hospital & Research Centre, Mumbai, between June 2016 to February 2017. NKSS was administered to each patient preoperatively. At 1 year, they were prospectively called for review and NKSS and FJS were administered. 151 patients attended the review clinic and 17 patients completed the forms with the help of their physiotherapist and sent them via email. 13 patients who could not do either, were excluded from the study. Thus, we had 168 patients (207 knees) whose complete data was analyzed. Of 168 patients, 37 were males and 131 were females, with an average age of 67 years (37–85). Patients were divided into two groups based on their FJS score - Group A (FJS<50) and Group B (FJS≥50). The demographics and NKSS in both groups were compared. The study was approved by our Institutional Review Board. Statistical analysis was done using SPSS software. Raw data statistics for FJS was determined and unpaired t-test used to compare all parameters in Groups A and B. Correlation of NKSS to FJS was analyzed using Pearson's correlation test.Introduction
Methods
Patient-reported outcome (PRO) data are variably collected before and after total hip/knee arthroplasty (THA/TKA). We assessed the generalizability of incentivized, prospectively collected PRO data for THA/TKA patient-reported outcome performance measure (PRO-PM) development. The Centers for Medicare & Medicaid Services (CMS) received PRO data voluntarily submitted by hospitals in a bundled payment model for THA/TKA procedures. Participating hospitals who collected and successfully submitted these data received an increase in their overall quality score, possibly resulting in a positive impact on model reconciliation payments. PRO data were collected from Medicare Fee-For-Service beneficiaries >= 65 years undergoing elective primary THA/TKA procedures from July 1 to August 31, 2016 at hospitals participating in the model. Pre-operative PRO and risk variable data were collected 0 – 90 days prior to surgery, while post-operative PRO data were collected 270 – 365 days following elective THA/TKA. PRO pre-op and post-op data were matched to Medicare claims data for determination of clinically eligible procedures and clinical comorbidities. We compared the characteristics of patients submitting PRO data to other elective primary THA/TKA recipients in the US.Introduction
Methods
New implants for total knee arthroplasty (TKA) are frequently introduced with the promise of improved performance. Infrequently there is accompanying data to document relative performance. The goal of this study was to evaluate the outcomes of an implant widely used for decades (Existing TKA), compared to a new implant (New TKA) from the same manufacturer. From October 2011-March 2015, 19 sites prospectively enrolled and implanted 752 Subjects with Existing TKA. Between November 2012 and May 2015, 23 sites (18 sites had enrolled Existing TKAs), implanted 1131 Subjects with the New TKA. Demographics were similar between groups. Subjects were seen preoperatively, <1-year, 1-year, and 2-years to collect patient reported outcome measures (PROMs), radiographs and any complications. PROMs consisted of Knee Injury and Osteoarthritis Outcome Score (KOOS) (permits WOMAC scoring), Oxford Knee Score (OKS), Patient's Knee Implant Performance (PKIP) and EQ5D-3L and a p-value of 0.01 was established for statistical significance for PROMs comparisons. Kaplan-Meier (KM) implant survivorship (revision of any component for any reason) estimates were calculated.Introduction
Methods
Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There is limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) to a matched cohort of patients undergoing TKA with no history of PKLR. All patients with history of ACL or MLK reconstruction who underwent TKA between 2007–2018 were identified in a single institution registry. A matched cohort was identified based on patient age, body mass index (BMI), sex, and year of surgery. The primary outcome measure was utilization of constrained implants. Secondary outcomes included rates of deep vein thrombosis (DVT), pulmonary embolism (PE), infection, postoperative transfusion, postoperative knee range of motion (ROM), revision surgery, and patient reported outcomes (Knee Injury and Osteoarthritis Outcome Score for joint replacement (KOOS, JR).Introduction
Methods
The revision rate of unicompartmental knee replacement (UKR) in national joint registries is much higher than that of total knee replacements and that of UKR in cohort studies from multiple high-volume centres. The reasons for this are unclear but may be due to incorrect patient selection, inadequate surgical technique, and inappropriate indications for revision. Meniscal bearing UKR has well defined evidence based indications based on preoperative radiographs, the surgical technique can be assessed from post-operative radiographs and the reason for revision from pre-revision radiographs. However, for an accurate assessment aligned radiographs are required. The aim of the study was to determine why the revision rate of UKR in registries is so high by undertaking a radiographic review of revised UKR identified by the United Kingdom's (UK) National Joint Registry (NJR). A novel cross-sectional study was designed. Revised medial meniscal bearing UKR with primary operation registered with the NJR between 2006 and 2010 were identified. Participating centres from all over the country provided blinded pre-operative, post-operative, and pre-revision radiographs. Two observers reviewed the radiographs.Introduction
Methods
Despite adoption of robust clinical pathways, narcotic administration within the inpatient setting is highly variable and may benefit from the implementation of standardized multi-modal pain management protocols. Total knee arthroplasty (TKA) candidates have historically received high doses of opioids within the perioperative period for the management of surgical pain. Healthcare systems have responded by improving opioid prescribing documentation and implementing narcotic-sparing pain protocols into TKA integrated care pathways (ICP). Despite these efforts, there are few technological platforms specifically designed to measure the narcotic burden immediately postoperatively. Here we present an early iteration of an inpatient narcotic administration-reporting tool, which normalizes patient narcotic consumption as an average daily morphine-milligram-equivalence (MME) per surgical encounter (MME/day/encounter) among total knee arthroplasty (TKA) recipients. This information may help orthopaedic surgeons visualize their individual granular inpatient narcotic prescribing habits individually and compared to other surgeons, while taking into consideration patient and procedure specific variables in order to optimize use and curtail unnecessary narcotic prescriptions.Summary
Introduction
Hypoalbuminemia has previously been identified as an independent predictor of postoperative complications following total knee arthroplasty (TKA). Given the morbidity and financial burden associated with TKA complications, significant effort has gone into identifying patients at increased risk for perioperative complications. The American Society of Anesthesiologists (ASA) physical status score has been utilized for risk stratification of surgical patients for many years and is a measure of overall health. However, it is unclear how measures like albumin compare to the prognostic ability of this type of global health measure. This study aims to elucidate the utility of preoperative albumin compared with that of the ASA score in predicting complications following TKA. Patients undergoing TKA between 2005 and 2015 were identified using the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were stratified based on preoperative hypoalbuminemia (<3.5 g/dL) and ASA score (≤ 2 vs. > 2). Multivariable regression analysis adjusted for age, sex, BMI, and smoking status was utilized to determine predictive potential of hypoalbuminemia and ASA score on each postoperative complication.Introduction
Methods
The statements contained in this document are solely those of the authors and do not necessarily reflect the views or policies of CMS. The authors assume responsibility for the accuracy and completeness of the information contained in this document. The Bundled Payments for Care Improvement (BPCI) initiative was introduced to reduce healthcare costs while maintaining quality. We examined data from a healthcare system comprised of five hospitals that elected to participate in the BPCI Major Joint Replacement of the Lower Extremity Model 2 initiative beginning July 1, 2015. We compared one hospital that did 507 BPCI knee cases to the four other hospitals that did 566 cases. Stratifying the data by hospital volume, we sought to determine if costs decreased during the BPCI period, how the savings were achieved, and if savings resulted in financial rewards for participation. The Medicare data included the target cost for each episode (based on historical data from 2009–2012 for each hospital that was adjusted quarterly) and actual Part A and Part B spending for 90 days. Using 1,836 primary knee replacements, we analyzed the costs associated with the anchor hospitalization, inpatient rehabilitation, skilled nursing facilities, home health, outpatient physical therapy and readmission to compare the 1,073 knees done during the 16-month BPCI initiative period with the 763 knees done during the 1-year period preceding BPCI participation. Owing to the nonparametric distribution of the cost data, a Mann-Whitney U test was used to compare the higher volume hospital with the four lower volume hospitals.Background
Methods
Patient expectations of total knee arthroplasty (TKA) can be managed through education. E-learning is the application of information technology to education. Providing information to patients at the place and time of their choosing, e-learning has the potential to broaden the reach of existing services for patients. This study evaluated whether an e-learning tool could affect whether patients felt their expectations were met and whether they were satisfied with surgery one year following primary TKA. We recruited consecutive patients with osteoarthritis and randomized them to either standard patient education (n=207), or to our standard patient education plus a new e-learning tool (n=209). Preoperative measures were completed following the patients’ Pre-Admission clinic (PAC) visit and prior to accessing the e-learning tool. Postoperative patient reported outcome measures (PROMs) were completed at six weeks, three months and one year after TKA. We used the Postoperative Expectation Questionnaire to measure the degree to which patient expectations had been met and the Patient Acceptable Symptom State (PASS) question to measure patient satisfaction at one year postoperative. We collected several PROMs for descriptive purposes including: new Knee Society Knee Scoring System (KSS); (Pre-Op and Post-Op versions), Knee injury and Osteoarthritis Outcome Score (KOOS), the Medical Outcomes Study 12-Item Short Form Health Survey, version 2 (SF-12), Hospital Anxiety and Depression Scale (HADS), Pain Catastrophizing Scale (PCS), University of California at Los Angeles (UCLA) Activity Score, and the Social Role Participation Questionnaire (SRPQ).Purpose
Method
Overwhelming evidence has established obesity as a risk factor for osteoarthritis (OA) of the knee. Randomized clinical trials such as the Look AHEAD study have shown long term successful intentional weight loss with an intensive lifestyle intervention (ILI) in overweight and obese type 2 diabetics. Weight loss can also decrease knee pain in persons who have OA, but it is unknown if intentional weight loss can reduce the risk of TKR. To answer this question, data from the Look AHEAD study were examined to determine if intentional weight loss could reduce the risk of TKR. Look AHEAD is a multicenter, randomized trial which began in August 2001 and follow-up continued for a median of 11.3 years at 16 academic centers. 5145 persons aged 45–76 with diabetes were randomized to either an ILI with reduced calorie consumption and increased physical activity designed or to diabetes support and education intervention (DSE). TKR events were ascertained every 6 months. Retrospective data of reported knee pain was assessed using the WOMAC knee pain questionnaire. Participants with partial TKR or revisions were excluded. Cox proportional hazard models were used to relate baseline BMI category (obese, Class I, Class II, or Class III obesity), baseline knee pain, and treatment group with TKR. Weight change category (lost<=5%, stable, gained>=2%) from baseline to year 1 follow-up by treatment assignment was also examined as a predictor of TKR after excluding TKR occurring prior to year 1.Introduction
Methods
Tranexamic acid (TXA) is proven to reduce blood loss following total knee arthroplasty (TKA), but there are limited data on the impact of similar dosing regimens in revision TKA that is associated with greater blood loss. The purpose of this multi-center randomized trial was to determine the optimal regimen to maximize the blood-sparing properties of TXA in revision TKA. 233 Septic and aseptic revision TKA from six-centers were randomized to either receive 1g pre-incision intravenous (IV) TXA, 1g pre- and post-incision IV TXA, 1g pre-incision IV and 1g intra-operative topical TXA, or three doses of 1950mg oral TXA given 2 hours pre-operatively, 6 hours post-operatively, and the morning of postoperative day 1. Randomization was performed based on type of revision to ensure equivalent distribution among groups. The primary outcome was reduction in hemoglobin. Power analysis determined 40 patients per group were necessary to identify a 1g/dL difference with an alpha of 0.05 and beta of 0.80. Per-protocol analysis involved regression analysis and two one-sided t-tests for equivalence.Introduction
Methods
This study explores whether subjects with bicruciate retaining TKRs (BiCR) have more normal knee biomechanics during level walking and stair ascent than subjects with posterior cruciate retaining TKRs (PCR). Due to anterior cruciate ligament (ACL) preservation, we expect BiCR subjects will not show the reduced flexion and altered muscle activation patterns characteristic of persons with TKRs. Motion and electromyography (EMG) data were collected during level walking and stair climbing for 16 BiCR subjects (4/12 m/f, 65±3 years, 30.7±7.0 BMI, 8/8 R/L), 17 PCR subjects (2/15 m/f, 65±7 years, 30.4±5.1 BMI, 7/10 R/L), and 17 elderly healthy control subjects (8/9 m/f, 55±10 years, 25.8±4.0 BMI, 10/7 R/L), using the point cluster marker set. Surface EMG electrodes were placed on the vastus medialis obliquus (VMO), rectus femoris (RF), biceps femoris (BF), and semitendinosus (ST) muscles. EMG data are reported as percent relative voluntary contraction (%RVC), normalized to the average peak EMG signals during level walking. Statistical nonparametric mapping was used for waveform analysis.Introduction
Methods
This study reports on the medium- to long-term implant survivorship
and patient-reported outcomes for the Avon patellofemoral joint
(PFJ) arthroplasty. A total of 558 Avon PFJ arthroplasties in 431 patients, with
minimum two-year follow-up, were identified from a prospective database.
Patient-reported outcomes and implant survivorship were analyzed,
with follow-up of up to 18 years.Aims
Patients and Methods
It has been hypothesized that patellofemoral pain, a common knee condition in adolescents and young adults, may be a precursor of degenerative joint changes and may ultimately lead to patellofemoral osteoarthritis. Since both conditions share several mechanical disease characteristics, such as altered contact area between the femur and patella and increased joint stress, we investigated whether these conditions share similar and different shape characteristics of the patella compared with normal controls. This cross-sectional study compared three different study populations: 32 patellofemoral pain subjects (mean age, 32 years (22 to 45); 72% female); 56 isolated radiological patellofemoral osteoarthritis subjects (mean age, 54 years (44 to 58); 89% female); and 80 healthy control subjects (mean age, 52 years (44 to 58); 74% female). Measurements included questionnaires, and lateral and skyline radiographs of the knee. Two separate 30-point 2D statistical shape models of the patella were created from the lateral and skyline radiographs. A general linear model was used to test for differences in standardized shape modes (a specific shape variant of the patella) between patellofemoral osteoarthritis, patellofemoral pain, and controls, using Bonferroni correction and adjustment for body mass index and gender.Objectives
Methods
The aim of this study was to identify the most effective regimen
of multiple doses of oral tranexamic acid (TXA) in achieving maximum
reduction of blood loss in total knee arthroplasty (TKA). In this randomized controlled trial, 200 patients were randomized
to receive a single dose of 2.0 g of TXA orally two hours preoperatively
(group A), a single dose of TXA followed by 1.0 g orally three hours
postoperatively (group B), a single dose of TXA followed by 1.0 g
three and nine hours postoperatively (group C), or a single dose
of TXA followed by 1.0 g orally three, nine, and 15 hours postoperatively
(group D). All patients followed a routine enhanced-recovery protocol.
The primary outcome measure was the total blood loss. Secondary
outcome measures were hidden blood loss (HBL), reduction in the
level of haemoglobin, the rate of transfusion and adverse events.Aims
Patients and Methods
The primary aim of this study was to determine the surgical team’s
learning curve for introducing robotic-arm assisted unicompartmental
knee arthroplasty (UKA) into routine surgical practice. The secondary
objective was to compare accuracy of implant positioning in conventional
jig-based UKA versus robotic-arm assisted UKA. This prospective single-surgeon cohort study included 60 consecutive
conventional jig-based UKAs compared with 60 consecutive robotic-arm
assisted UKAs for medial compartment knee osteoarthritis. Patients
undergoing conventional UKA and robotic-arm assisted UKA were well-matched
for baseline characteristics including a mean age of 65.5 years
(Aims
Patients and Methods
It has been suggested that mobile-bearing total knee arthroplasty
(TKA) might lead to better outcomes by accommodating some femorotibial
rotational mismatch, thereby reducing contact stresses and polyethylene
wear. The aim of this study was to determine whether there is a
difference between fixed- and mobile-bearing versions of a contemporary
TKA with respect to durability, range of movement (ROM) and function,
ten years postoperatively. A total of 240 patients who were enrolled in this randomized
controlled trial (RCT) underwent a primary cemented TKA with one
of three tibial components (all-polyethylene fixed-bearing, modular
metal-backed fixed-bearing and mobile-bearing). Patients were reviewed
at a median follow-up of ten years (IQR 9.2 to 10.4).Aims
Patients and Methods
The objective of this study was to compare early postoperative
functional outcomes and time to hospital discharge between conventional
jig-based total knee arthroplasty (TKA) and robotic-arm assisted
TKA. This prospective cohort study included 40 consecutive patients
undergoing conventional jig-based TKA followed by 40 consecutive
patients receiving robotic-arm assisted TKA. All surgical procedures
were performed by a single surgeon using the medial parapatellar
approach with identical implant designs and standardized postoperative inpatient
rehabilitation. Inpatient functional outcomes and time to hospital
discharge were collected in all study patients.Aims
Patients and Methods
Researchers continue to seek easier ways to evaluate the quality of bone and screen for osteoporosis and osteopenia. Until recently, radiographic images of various parts of the body, except the distal femur, have been reappraised in the light of dual-energy X-ray absorptiometry (DXA) findings. The incidence of osteoporotic fractures around the knee joint in the elderly continues to increase. The aim of this study was to propose two new radiographic parameters of the distal femur for the assessment of bone quality. Anteroposterior radiographs of the knee and bone mineral density (BMD) and T-scores from DXA scans of 361 healthy patients were prospectively analyzed. The mean cortical bone thickness (CBTavg) and the distal femoral cortex index (DFCI) were the two parameters that were proposed and measured. Intra- and interobserver reliabilities were assessed. Correlations between the BMD and T-score and these parameters were investigated and their value in the diagnosis of osteoporosis and osteopenia was evaluated.Objectives
Methods
The primary aim of this study was to assess the rate of patient
satisfaction one year after total knee arthroplasty (TKA) according
to the focus of the question asked. The secondary aims were to identify
independent predictors of patient satisfaction according to the
focus of the question. A retrospective cohort of 2521 patients undergoing a primary
unilateral TKA were identified from an established regional arthroplasty
database. Patient demographics, comorbidities, Western Ontario and
McMaster Universities Osteoarthritis Index (WOMAC) and 12-Item Short-Form
Health Survey (SF-12) scores were collected preoperatively and one
year postoperatively. Patient satisfaction was assessed using four
questions, which focused on overall outcome, activity, work, and
pain. Logistic regression analysis was used to identify independent
preoperative predictors of increased stiffness when adjusting for
confounding variables.Aims
Patients and Methods
To compare the effect of femoral bone tunnel configuration on tendon-bone healing in an anterior cruciate ligament (ACL) reconstruction animal model. Anterior cruciate ligament reconstruction using the plantaris tendon as graft material was performed on both knees of 24 rabbits (48 knees) to mimic ACL reconstruction by two different suspensory fixation devices for graft fixation. For the adjustable fixation device model (Socket group; group S), a 5 mm deep socket was created in the lateral femoral condyle (LFC) of the right knee. For the fixed-loop model (Tunnel group; group T), a femoral tunnel penetrating the LFC was created in the left knee. Animals were sacrificed at four and eight weeks after surgery for histological evaluation and biomechanical testing.Objectives
Methods
This study investigated the influence of body mass index (BMI)
on patients’ function and quality of life ten years after total
knee arthroplasty (TKA). A total of 126 patients who underwent unilateral TKA in 2006
were prospectively included in this retrospective study. They were
categorized into two groups based on BMI: < 30 kg/m2 (control)
and ≥ 30 kg/m2 (obese). Functional outcome was assessed
using the Knee Society Function Score (KSFS), Knee Society Knee
Score (KSKS), and Oxford Knee Score (OKS). Quality of life was assessed
using the Physical (PCS) and Mental Component Scores (MCS) of the 36-Item
Short-Form Health Survey.Aims
Patients and Methods
Primary (or spontaneous) and secondary osteonecrosis of the knee
can lead to severe joint degeneration, for which either total or
unicompartmental arthroplasty may be considered. However, there
are limited studies analyzing outcomes of unicompartmental knee arthroplasties
(UKAs) for osteonecrosis involving an isolated compartment of the
knee. The aims of this study were to analyze outcomes of UKAs for
osteonecrosis with specific focus on 1) survivorship free of any
revision or reoperation, 2) risk factors for failure, 3) clinical outcomes,
and 4) complications. A total of 45 patients underwent 46 UKAs for knee osteonecrosis
between 2002 and 2014 at our institution (The Mayo Clinic, Rochester,
Minnesota). Twenty patients (44%) were female; the mean age of the
patients was 66 years, and mean body mass index (BMI) was 31 kg/m2. Of
the 46 UKAs, 44 (96%) were medial UKAs, and 35 (76%) were fixed-bearing
design. Mean mechanical axis postoperatively was 1.5° varus (0°
to 5° varus); 41 UKAs (89%) were performed for primary osteonecrosis.
Mean follow-up was five years (2 to 12)Aims
Patients and Methods
To investigate the risk factors for progression of articular
cartilage damage after anatomical anterior cruciate ligament (ACL)
reconstruction. A total of 174 patients who underwent second-look arthroscopic
evaluation after anatomical ACL reconstruction were enrolled in
this study. The graded condition of the articular cartilage at the
time of ACL reconstruction was compared with that at second-look
arthroscopy. Age, gender, body mass index (BMI), ACL reconstruction
technique, meniscal conditions, and other variables were assessed
by regression analysis as risk factors for progression of damage
to the articular cartilage.Aims
Patients and Methods
The primary stability of the cementless Oxford Unicompartmental Knee Replacement (OUKR) relies on interference fit (or press fit). Insufficient interference may cause implant loosening, whilst excessive interference could cause bone damage and fracture. The aim of this study was to identify the optimal interference fit by measuring the force required to seat the tibial component of the cementless OUKR (push-in force) and the force required to remove the component (pull-out force). Six cementless OUKR tibial components were implanted in 12 new slots prepared on blocks of solid polyurethane foam (20 pounds per cubic foot (PCF), Sawbones, Malmo, Sweden) with a range of interference of 0.1 mm to 1.9 mm using a Dartec materials testing machine HC10 (Zwick Ltd, Herefordshire, United Kingdom) . The experiment was repeated with cellular polyurethane foam (15 PCF), which is a more porous analogue for trabecular bone.Objectives
Materials and Methods
The aim of this study was to evaluate the long-term inducible
displacement of cemented tibial components ten years after total
knee arthroplasty (TKA). A total of 15 patients from a previously reported prospective
trial of fixation using radiostereometric analysis (RSA) were examined
at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine
RSA examinations were acquired at one week, one year, and two years
postoperatively and at final follow-up. Weight-bearing RSA examinations
were also undertaken with the operated lower limb in neutral and
in maximum internal rotation positions. Maximum total point motion
(MTPM) was calculated for the longitudinal and inducible displacement examinations
(supine Aims
Patients and Methods
The aims of this study were to compare the efficacy and safety
of intra-articular and intravenous (IV) tranexamic acid (TXA) in
controlling perioperative blood loss in total knee arthroplasty
(TKA) using a randomized, double-blinded equivalence trial. A total of 182 patients aged between 45 and 75 years undergoing
unilateral TKA at a tertiary centre were randomized to receive TXA,
either 1.5 g intra-articularly after closure of the wound (n = 91)
or two doses of 10 mg/kg IV (n = 91). The primary outcome measure
was the reduction in the level of haemoglobin (Hb) in the blood
on the fifth postoperative day. Secondary outcome measures were
the total, visible, and hidden blood losses (TBL, VBL, HBL). We
assumed equivalence of the primary outcome in both routes with a
margin of ± 0.35gm/dl. Block randomization using computer-generated
random numbers was used. The patients and the assessor of outcome were
blinded.Aims
Patients and Methods
It has been suggested that the use of a pilot-hole may reduce the risk of fracture to the lateral cortex. Therefore the purpose of this study was to determine the effect of a pilot hole on the strains and occurrence of fractures at the lateral cortex during the opening of a high tibial osteotomy (HTO) and post-surgery loading. A total of 14 cadaveric tibias were randomized to either a pilot hole (n = 7) or a no-hole (n = 7) condition. Lateral cortex strains were measured while the osteotomy was opened 9 mm and secured in place with a locking plate. The tibias were then subjected to an initial 800 N load that increased by 200 N every 5000 cycles, until failure or a maximum load of 2500 N.Aim
Materials and Methods
The primary aim of this study was to assess whether patient satisfaction
one year after total knee arthroplasty (TKA) changed with longer
follow-up. The secondary aims were to identify predictors of satisfaction
at one year, persistence of patient dissatisfaction, and late onset
dissatisfaction in patients that were originally satisfied at one year. A retrospective cohort consisting of 1369 patients undergoing
a primary TKA for osteoarthritis that had not undergone revision
were identified from an established arthroplasty database. Patient
demographics, comorbidities, Western Ontario and McMaster Universities
Osteoarthritis Index (WOMAC) scores, and Short Form 12 (SF-12) questionnaire
scores were collected preoperatively, and one and five years postoperatively.
In addition, patient satisfaction was assessed at one and five years
postoperatively. Logistic regression analysis was used to identify
independent predictors of satisfaction at one and five years.Aims
Patients and Methods
Meniscal allograft transplantation is undertaken to improve pain
and function in patients with a symptomatic meniscal deficient knee
compartment. While case series have shown improvements in patient
reported outcome measures (PROMs), its efficacy has not been rigorously
evaluated. This study aimed to compare PROMs in patients having
meniscal transplantation with those having personalized physiotherapy
at 12 months. A single-centre assessor-blinded, comprehensive cohort study,
incorporating a pilot randomized controlled trial (RCT) was performed
on patients with a symptomatic compartment of the knee in which
a (sub)total meniscectomy had previously been performed. They were
randomized to be treated either with a meniscal allograft transplantation
or personalized physiotherapy, and stratified for malalignment of
the limb. They entered the preference groups if they were not willing
to be randomized. The Knee injury and Osteoarthritis Outcome Score (KOOS),
International Knee Documentation Committee (IKDC) score and Lysholm
score and complications were collected at baseline and at four,
eight and 12 months following the interventions.Aims
Patients and Methods
The aims of this study were to compare the efficacy of two agents,
aspirin and warfarin, for the prevention of venous thromboembolism
(VTE) after simultaneous bilateral total knee arthroplasty (SBTKA),
and to elucidate the risk of VTE conferred by this procedure compared
with unilateral TKA (UTKA). A retrospective, multi-institutional study was conducted on 18
951 patients, 3685 who underwent SBTKA and 15 266 who underwent
UTKA, using aspirin or warfarin as VTE prophylaxis. Each patient
was assigned an individualised baseline VTE risk score based on
a system using the Nationwide Inpatient Sample. Symptomatic VTE,
including pulmonary embolism (PE) and deep vein thrombosis (DVT),
were identified in the first 90 days post-operatively. Statistical
analyses were performed with logistic regression accounting for
baseline VTE risk.Aims
Patients and Methods
Patient-specific (PS) implantation surgical technology has been introduced in recent years and a gradual increase in the associated number of surgical cases has been observed. PS technology uses a patient’s own geometry in designing a medical device to provide minimal bone resection with improvement in the prosthetic bone coverage. However, whether PS unicompartmental knee arthroplasty (UKA) provides a better biomechanical effect than standard off-the-shelf prostheses for UKA has not yet been determined, and still remains controversial in both biomechanical and clinical fields. Therefore, the aim of this study was to compare the biomechanical effect between PS and standard off-the-shelf prostheses for UKA. The contact stresses on the polyethylene (PE) insert, articular cartilage and lateral meniscus were evaluated in PS and standard off-the-shelf prostheses for UKA using a validated finite element model. Gait cycle loading was applied to evaluate the biomechanical effect in the PS and standard UKAs.Objectives
Methods
The aim of this independent multicentre study was to assess the
mid-term results of mobile bearing unicondylar knee arthroplasty
(UKA) for isolated lateral osteoarthritis of the knee joint. We retrospectively evaluated 363 consecutive, lateral UKAs (346
patients) performed using the Oxford domed lateral prosthesis undertaken
in three high-volume knee arthroplasty centres between 2006 and
2014. Mean age of the patients at surgery was 65 years (36 to 88)
with a mean final follow-up of 37 months (12 to 93)Aims
Patients and Methods
The purpose of this study was to evaluate trends in opioid use
after unicompartmental knee arthroplasty (UKA), to identify predictors
of prolonged use and to compare the rates of opioid use after UKA,
total knee arthroplasty (TKA) and total hip arthroplasty (THA). We identified 4205 patients who had undergone UKA between 2007
and 2015 from the Humana Inc. administrative claims database. Post-operative
opioid use for one year post-operatively was assessed using the
rates of monthly repeat prescription. These were then compared between
patients with and without a specific variable of interest and with
those of patients who had undergone TKA and THA.Aims
Materials and Methods
Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA. We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions.Objectives
Methods
In Asia and the Middle-East, people often flex their knees deeply
in order to perform activities of daily living. The purpose of this
study was to investigate the 3D kinematics of normal knees during
high-flexion activities. Our hypothesis was that the femorotibial
rotation, varus-valgus angle, translations, and kinematic pathway
of normal knees during high-flexion activities, varied according
to activity. We investigated the Aims
Materials and Methods