Instability is a common reason for revision after total knee arthroplasty. A balanced flexion gap is likely to enhance stability throughout the arc of motion. This is achieved differently by the gap balancing and measured resection techniques. Given similar clinical results with the two techniques, one would expect similar rotation of the femoral component in the axial plane. We assessed posterior-stabilized femoral component axial rotation placed with computer navigation and a modified gap balancing technique. We hypothesized that there would be little variation in rotation. 90 surgeons from 8 countries used a modified gap-balancing technique and the same posterior-stabilized implant for this retrospective study. Axial rotation of the femoral component was collected from a navigation system and reported relative to the posterior condylar line. Patients were stratified by their preoperative coronal mechanical alignment (≥ 3° varus, < 3° varus to < 3° valgus, and ≥ 3° valgus).Introduction
Methods
Initial post-operative implant instability leads to impaired osseointegration, one of the most common reasons for aseptic loosening and revision surgery. In this study, we developed a novel murine model of implant instability and demonstrated the anabolic effect of immediate and delayed intermittent Parathyroid Hormone (iPTH) treatment in the setting of instability-induced osseointegration failure. 3D-printed titanium implants were inserted in an oversized drill-hole in the tibia of C57Bl/6 mice (n=54). After implantation, the mice were randomly divided in 3 treatment groups (control: PBS-vehicle; iPTH; delayed iPTH). Radiographic analysis was performed to confirm signs of implant loosening. Peri-implant tissue formation was assessed through histology. Osseointegration was assessed through µCT and biomechanical pullout testing.Introduction
Methods
Secondary osteonecrosis of the knee (SOK) generally occurs in relatively young patients in their working years; at advanced stages of SOK, the only viable surgical option is total knee arthroplasty (TKA). We conducted a retrospective study to investigate implant survivorship, clinical and radiographic outcomes, and complications of cemented TKA with/without patellar resurfacing for SOK. Thirty-eight cemented TKAs in 27 patients with non-traumatic SOK with a mean age 43 years (range 17–65) were retrospectively reviewed. Twenty-one patients (78%) were female. Mean body mass index was 31 kg/m2 (range 20–48); 11 patients (41%) received bilateral TKAs. Twenty patients (74%) had a history of corticosteroid use and 18% had a history of alcohol abuse. Patellar osteonecrosis was coincidentally found in six knees (16%), all of which had no anterior knee pain and had no patellofemoral joint collapse. The mean follow-up was 7 years (range 2–12). Knee Society Score (KSS) and radiographic outcomes were evaluated at 6 weeks, 1 year, then every 2–3 years thereafter.Background
Methods
The evaluation and management of outcomes risk has become an essential element of a modern total joint replacement program. Our multidisciplinary team designed an evidence-based tool to address modifiable risk factors for adverse outcomes after primary hip and knee arthroplasty surgery. Our protocols were designed to identify, intervene, and mitigate risk through evidence-based patient optimization. Nurse navigators screened patients preoperatively, identified and treated risk factors, and followed patients for 90 days postoperatively. We compared patients participating in our optimization program (N=104) to both a historical cohort (N=193) and a contemporary cohort (N=166).Background
Methods
Early mobilization after total joint arthroplasty decreases postoperative complications and optimizes future functional outcomes. The purpose of this study was to evaluate the effectiveness of a supervised patient ambulation program following total joint arthroplasty. In 2014, our institution initiated a mandatory supervised patient ambulation program termed “No One Walks Alone” (NOWA). The program requires that all patients who mobilize are accompanied by a nurse or physical therapist. Gait belts are worn whenever a patient ambulates. Bed and chair alarms are utilized to alert if a patient tries to ambulate alone. If a patient experiences a fall, he or she is immediately evaluated by the nursing staff, and details regarding the fall and any injury sustained are documented. A retrospective review of patients undergoing total knee or hip arthroplasty between 2011–2017 was conducted. Patients who had surgery between 2011–2013, before the program, were included in the pre-implementation group (N= 3,069) and those having surgery between 2016–2017, after the program started, were included in the post-implementation group (N=3,947). The incidence of patient falls, fall-related complications were compared between groups.Background
Methods
Bundled Payments (BP) were a revolutionary new experiment for CMS that tested whether risk sharing for an episode of care would improve quality and reduce costs. The initial success of BP accelerated their growth as evidence by the launch of both mandatory and commercial bundles. Success in BP is dependent on the target price and the opportunity to reduce avoidable costs during the episode of care. There is concern that the aggressive target pricing methodology in the new model (BPCI-Advanced) penalizes high performing groups that already achieved low episode costs through prior experience and investment in BP. We hypothesize that this methodology incorporates unsustainable downward trends on target prices to a point beyond reasonableness for efficient groups to reduce additional costs and will lead to a large percentage of groups opting out of BPCI-A in favor of a return to fee for service (FFS) reimbursement. Using CMS data, we compared the target price factors for hospitals that participated in both BPCI classic (2013 –2018) and BPCI Advanced (beginning 10/2018), referred to as “legacy hospitals”, with hospitals that only participated in BPCI Advanced (beginning 10/2018). With the rebasing of BPCI-A target prices in Jan 2020 and the opportunity for participants to drop out of individual episode types or the program all together, we compared the retention of episode types that hospitals initially enrolled at the onset of BPCI-A with the current enrollment in 2020. Locally, we analyzed the BPCI-A target price factors across hospitals for a large orthopaedic practice that participated in BPCI Classic and the impact it had on the financial incentive/disincentive to remain in the lower extremity joint replacement episode type in 2020.Introduction
Methods
Treatment of prosthetic joint infection (PJI) following total knee arthroplasty (TKA) may guided by PJI classification, taking into account infection duration and potential for biofilm formation. Debridement, antibiotics and implant retention (DAIR) is recommended for ‘post-operative’ and ‘acute’ haematogenous PJI. However, the time cut-off for ‘post-operative’ PJI varies across classification systems. Furthermore, poor DAIR success rates have been reported in acute haematogenous PJIs. This study aimed to determine the success of DAIR in a large cohort of PJIs, and assess the utility of current classification systems for predicting DAIR outcomes. In this multicentre retrospective, cohort study, we identified 230 patients undergoing DAIR for first episode PJI following primary TKA. Patient demographics, disease and surgical factors were identified, and PJI subtype, post-operative antibiotic regime and treatment outcomes were recorded. Statistical analysis was performed to identify factors associated with failed DAIR, and success rates were analysed by multiple classification systems using receiver operating characteristic (ROC) curves.Introduction
Method
Our objective is to describe early and midterm results with the use of a new knee prosthesis as an articulating spacer in planned two-stage management for infected total knee arthroplasty. As a second objective, we compared outcomes between the group with a retained first stage and those with a completed 2-stage revision. Forty-seven patients (48 knees) from January 2012 and November 2017 underwent a 2-stage exchange with an articulating spacer with new implants was used for a chronic knee periprosthetic joint infection with a mean follow-up of 3.7 years (2–6.5 years). The most frequently identified infecting organism was MSSA (31%), MRSA (21%) or MRSE (20%). At the first stage, a new PS femoral component and a new all-polyethylene posterior stabilized (PS) tibial component or a standard PS tibial liner were cemented with antibiotic-cement, typically 3.6 gm tobramycin and vancomycin 1.5 gm. IV antibiotics for six weeks were administered. The planned reimplantation was at 3 months, but ninetteen spacers (14 all poly tibias and 5 tibial liner) were retained for over 12 months. Postoperative assessment included knee range of motion (ROM), quality of life (QOL) scores (SF-12, WOMAC, KOOS, Oxford, and UCLA scores), and a satisfaction scale from 0–100%.Introduction
Methods
Septic arthritis of the native knee often results in irreversible joint damage leading to the need for a total knee arthroplasty (TKA). This study examines the mid-term risk of periprosthetic joint infection (PJI), aseptic revision, any revision, and any reoperation in primary TKAs after septic arthritis of the native knee compared to a control cohort of primary TKAs performed for osteoarthritis (OA). We retrospectively identified 215 primary TKAs performed between 1971 and 2016 at a single institution following septic arthritis of the native knee. Eighty-two percent (177 cases) were treated in a single setting, whereas a two-stage exchange arthroplasty protocol was utilized in 18% (39 cases) for ongoing or suspected active native knee septic arthritis. Each case was matched 1:1 based on age, sex, body mass index (BMI), and surgical year to a primary TKA for OA. Mean age and BMI were 63 years and 30 kg/m2, respectively. Mean follow-up was 9 years.Introduction
Methods
Perioperative optimization efforts have improved outcomes following primary total knee arthroplasty (TKA). However, morbidly obese patients continue to have increased rates of complications. The purpose of this study was to assess if rates of early complications after TKA have similarly improved for both morbidly obese and non-morbidly obese patients. Elective, primary TKA patients from 2011–2018 were identified in the National Surgical Quality Improvement Program database. Patients were stratified by body mass index (BMI) <40 kg/m2 and ≥40 kg/m2. Thirty-day rates of infectious complications, readmissions, and reoperation were assessed. Trends in these endpoints over the study period were compared between BMI groups utilizing odds ratios (OR) and multivariate analyses.Introduction
Methods
The use of intraoperative liposomal bupivacaine (LB) peri-articular injection has been highly debated for total knee arthroplasty (TKA). We evaluated the effect of an institutional-wide discontinuation of intraoperative LB on immediate postoperative pain scores, opioid consumption, and objective functional outcomes. Between July 1, 2019 and November 30, 2019, an institutional policy discontinued use of intraoperative LB, while the volume of non-LB with epinephrine was increased from 40-ml to 60-ml. A historical cohort was derived from patients undergoing TKA between January 1, 2019 and June 30, 2019. All patients received the same opioid sparing protocol, minimizing variability in prescribing habits. No adductor canal blocks/pumps were utilized. Nursing documented verbal rating scale (VRS) pain scores were collected from our electronic data warehouse and averaged per patient per 12-hour interval. Opiate administration events were derived as Morphine Milligram Equivalences (MMEs) per patient per 24-hour interval. To assess immediate postoperative functional status, the validated Activity Measure for Post-Acute Care (AM-PAC) tool was utilized. All time events were calculated relative to TKA completion instant.Introduction
Material and Methods
One of the main considerations in the revision TKR setting is deciding on the level of constraint to be utilized once the bone defects have been reconstructed. There is a fear that employing a maximally constrained insert could compromise long term results. We report on a consecutive series of full tibial and femoral component revisions all treated with a maximally conforming insert and followed for a minimum of 5 years. The study group consisted of 76 consecutive revision TKR in 76 patients where both the femur and the tibia were revised. 4 patients died and 6 were lost to follow up. Final cohort had an average age of 70 years, average BMI of 31 and there were 39 males in the group. Average time to revision was 7 years (range 1–10 years) and the reasons for revision included infection in 28, aseptic loosening 26, osteolysis and poly wear in 9 and 13 other. All were treated with the same revision system and an identical maximally conforming tibial rotating platform insert and followed for an average of 7 years (range 5–14 years).Introduction
Materials and Methods
Revision total knee arthroplasty (rTKA) is a complex procedure with increased risk of blood loss and transfusions. The Musculoskeletal Infection Society has included D-dimer as a serology marker for peri-prosthetic infection. The study's intent is to understand the impact of preoperative D-dimer levels on blood loss and venous thromboembolism in revision TKA. Following IRB approval, rTKA performed by a single surgeon between January 1, 2017 and December 31, 2019 were reviewed. Inclusion criteria consisted of pre-operative D-Dimer, cemented revision TKA of one or both components under tourniquet control. 89 patients met the criteria including 37 males (41.6%) and 52 females (58.4%). Mean ages were 65 for males and 67 for females. The data revealed 54 patients (61%) had an elevated D-dimer (group 1) and 35 patients (39%) had a normal D-dimer (group 2). Sex stratification showed 21 males (57.8%) and 33 females (63.5%) with elevated D-dimer. TXA protocol included 2 grams intravenous (82 patients) or 2 grams intra-articular application (7 patients). Post-operative anticoagulation included Lovenox 40mg daily for 2 weeks followed by aspirin 325 twice daily for 4 weeks. Pre-operative and post-operative hemoglobin, transfusion rates and post-operative VTE within 90 days of surgery were recorded.Background
Methods
Unexpected cancellation of scheduled total joint arthroplasty (TJA) procedures create patient distress and are disruptive to the clinical team. The purpose of this study was to identify the etiology of cancellation for scheduled TJA and to determine the subsequent fate of those patients. A consecutive series of 11670 primary THA and TKA patients at a single institution was reviewed from January 2013 through March 2017. All patients who were scheduled for a primary THA or TKA and subsequently cancelled were identified. The etiology of cancellation and time to rescheduling were recorded. Univariate analysis and cox regression models were performed.Introduction
Methods
There are case series of debonding of the ATTUNE® tibial component introduced in 2013. We studied the early clinical results of this total knee arthroplasty (TKA) and compared it to other designs at one hospital. This is a retrospective study of 223 consecutive, non-randomized, cemented fixed-bearing posterior-stabilized ATTUNE® TKAs at one hospital by 5 surgeons from 2013 through 2017. We excluded 4 knees with early infection and 53 with follow-up less than 6 months. Of 166 TKAs reviewed, the mean patient age was 63.8 years, mean BMI 32, and mean follow-up 25 months. We compared this to a “control” cohort of 511 TKAs of other manufacturers performed at the same hospital. The endpoints were revision performed and revision pending.Background
Methods
Both mobile bearing and fixed bearing unicompartmental knee arthroplasty (UKA) have demonstrated clinical success. However, much debate persists about the superiority of a single design. Currently most clinical data is based on high volume centers data, however to reduce bias, we undertook a through review of retrospective national joint registries. In this study, we aim to investigate UKA implant utilization and survivorship between 2000 and 2018. Ten annual joint registry reports of various nations were reviewed. Due to the variable statistical methods of reporting implant use and survivorship we focused on three registries: Australia (AOANJRR), New Zealand (NZJR), United Kingdom (NJR) for uniformity. We evaluated UKA usage, survivorship, utilization and revision rates for each implant. Implant survivorship was reported in the registries and was compared within nations due to variation in statistical reporting.Introduction
Methods
Lateral Unicompartmental Knee Arthroplasty (UKA) is a recognised treatment option in the management of lateral Osteoarthritis (OA) of the knee. Whilst there is extensive evidence on the indications and contraindcations in Medial UKA there is limited evidence on this topic in Lateral UKA. The aim of this study was to assess our experience of mobile lateral UKR and to look specifically at the effect of Contraindications on the outcome. A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and presence of full- thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated.Background
Method
Unicompartmental knee arthroplasty (UKA) patients with knee partial thickness cartilage loss have inferior functional performance compared to those with full thickness loss. Therefore, the aim of the present study was to investigate on the association between postoperative patients' joint awareness and satisfaction and preoperative radiographic osteoarthritis (OA) Ahlbäck grade in subjects undergoing robotic arm-assisted UKA. This retrospective observational study includes 675 patients (681 knees) undergoing robotic arm-assisted UKA at two centres between January 2014 and May 2019. Pre-operatively, knee radiographs were performed, and Ahlbäck OA grade was measured by two independent observers. Post-operatively, patients were administered the Forgotten-Joint-Score-12 (FJS-12) and 5-Level-Likert-Scale to assess joint awareness and satisfaction. Postoperative complications and revisions were recorded. Correlations were described between FJS-12, satisfaction and OA grade by means of an adjusted multivariate statistical analysis.Background
Methods
Debridement, Antibiotics and Implant Retention (DAIR) remains the norm for the treatment of acute periprosthetic joint infection (PJI) despite less than optimal success rates. Intraosseous (IO) administration of vancomycin has been shown to have significantly increased local bone and tissue concentrations compared to systemic antibiotics, with lower systemic antibiotic levels compared to intravenous. The purpose of this study was to evaluate if the addition of IO regional antibiotics to our protocol at the time of DAIR would improve outcomes. A retrospective review of 35 PJI TKA patients who underwent DAIR combined with IO vancomycin (500mg) was performed with minimum 12-month follow-up. 26 patients were treated for acute perioperative or acute hematogenous infections following primary TKA. Nine were treated for chronic infections with components that were considered unresectable (ie) constructs with ingrown cones, sleeves, or long cemented stems in elderly comorbid patients. Primary outcome was defined by no reoperations for infection nor clinical signs or symptoms of PJI.Introduction
Methods
Management of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is a challenging task. Antibiotic management remains elusive due to differences in epidemiology and resistance between countries and reports. Increasing resistance of bacteria is a concern. The aim of this study was to investigate the development of antibiotic resistance of main causative bacteria in a single center. A retrospective review of all revision TKA between 2006 and 2018 in a tertiary referral center was performed. Included were cases meeting the consensus criteria for PJI with at least two positive cultures. Three chronological groups were created using a two-step cluster analysis.Introduction
Methods
Instability following total knee arthroplasty is a leading cause of failure and is often treated with component revision. The goal of this study was to determine if isolated tibial polyethylene insert exchange (ITPIE) to a higher-level constraint would afford similar outcomes to component revision in the properly selected patient. We retrospectively evaluated 176 consecutive patients between 2016–2017 who were revised for symptomatic instability at a single institution. Demographic information and level of constraint preoperatively and postoperatively were documented. Radiographic parameters were also recorded for patients undergoing ITPIE. Outcome measures included all cause re-revision rates as well as patient reported outcome measures (PROMs) obtained preoperatively and at minimum 1-yr follow up. Descriptive analysis including sample t-test and chi square test were performed with statistical significance set at p <0.05.Introduction
Methods
Total knee arthroplasty (TKA) femoral components are known to wear and roughen with clinical use, and reaction to metal is a well-documented complication of TKA. Ceramic materials are resistant to wear and corrosion, but the surface wear of ceramic femoral components in TKA has not been reported. This study measured the changes in roughness and mass lost from cobalt-chromium (CoCr) femoral components tested in a knee simulator, and compared them to those observed in ceramic components. Six cast CoCr femoral components were tested in a knee simulator bearing against UHMWPE, with high-kinematics/high-load waveforms. Roughness and scratches were measured via optical profilometry. Scratch volume was equated to mass lost from abrasive wear, while nano-particulate wear and corrosion were estimated from the change in the distance of the surface to the depth of the scratches after increasing numbers of cycles. Three magnesia-stabilized zirconia femoral components that had been wear tested to 15 million cycles were compared with the CoCr components.Introduction
Methods
Pitting damage on implants has been reported and attributed to use of electrocautery. This study aimed to distinguish how different TKA bearing surfaces are susceptible to this type of damage and whether surgeons were aware that this damage can occur. A survey was sent to Hip and Knee Society members to determine what percentage of adult reconstructive surgeons use electrocautery after implantation of components. Three bearing surfaces for primary TKA were selected: CoCr, Oxinium, and zirconium nitride (ZrN) to be damaged by electrocautery with a monopolar (MP, Bovie) and bipolar (BP, Aquamantys) electrocautery with three different energy settings. A comparison of surface damage and backscatter elemental analysis using SEM was performed. Average roughness (Ra), maximal peak-to-valley height (Rz,), kurtosis (Rk), and skewness (Rsk) measurements were collected using a profilometer (DektakXT, Bruker, Tucson, AZ) with a 2.5µm radius stylus to assess an area of 3.8mm by 3.2mm in the central portion of the area for each MP and BP energy setting used to impart damage to the bearing surfaces. A similar undamaged area for each bearing surface was also measured for roughness parameter comparison.Introduction
Methods
The purpose of this study was to compare the radiographic outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). Postoperative radiographic outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic center were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiographically measured to identify outliers. Clinical results at 4–6 weeks postoperative were compared to a control cohort of total knee arthroplasty (TKA) patients from our institution.Introduction
Materials & Methods
The COVID-19 pandemic caused an abrupt disruption in fellowship training, with most in-person teaching ceasing in mid-March 2020. An online lecture series was quickly initiated named the Fellows Online COVID-19 AAHKS Learning (FOCAL) initiative. This study will summarize the results of that initiative. Beginning March 31, 2020, an online teaching program was initiated. Adult reconstruction fellows and senior residents with interest in adult reconstruction were invited to participate in the free, live, online education sessions. Faculty from well-respected training institutions from around the country volunteered their time to host the initiative, choosing topics to present, ranging from hip (13 lectures) and knee (9), to practice management/miscellaneous (12). All sessions were recorded and posted on the society website for viewing. Attendee registrations were tracked via the online platform and the maximum number of attendees per session was recorded. A survey was administered to attendees for feedback.Background
Methods
The objective of this study is to assess the use of ultrasound (US) as a radiation free imaging modality to reconstruct three-dimensional knee anatomy. An OEM US system is fitted with an electromagnetic (EM) tracker that is integrated into the US probe, allowing for 3D tracking of probe and femur and tibia. The raw US RF signals are acquired and using real time signal processing, bone boundaries are extracted. Bone boundaries are then combined with the EM sensor information in a 3D point cloud for both femur and tibia. Using a statistical shape model, the patient specific surface is reconstructed by optimizing bone geometry to match the point clouds. An accuracy analysis was then conducted for 11 cadavers by comparing the 3D US models to those created using CT scans.Introduction
Methods
Mechanical axis limb alignment in total knee arthroplasty (TKA) has demonstrated excellent long-term survivorship; however, patient satisfaction continues to demand improvement. Alternative emerging alignment concepts including kinematic and tibial constitutional varus have been introduced but remain controversial. The purpose of this study was to evaluate outcomes and patient satisfaction following TKA with tibial components placed in constitutional varus alignment. This was a retrospective cohort analysis from a total joint registry of 114 patients with preoperative varus deformity who underwent primary TKA with tibial component placed in 1–3 degrees of constitutional varus. The group included 59 males (52%) and 55 (48%) females with a mean age of 67 years (range 43 – 85) and mean BMI of 32.0 kg/m2 (range 21 – 51 kg/m2) with a minimum 1 year follow-up. Patients were stratified into 3 groups based on the preoperative varus alignment: Group A between 1°- 5° varus (43 knees), Group B between 6°- 10° (56 knees), and Group C greater than 10° (16 knees). The target constitutional tibial varus alignment was selected based on the extent of the patient's deformity.Introduction
Methods
Cementless TKA offers the potential for strong fixation through biologic fixation technology as compared to cemented TKA where fixation is achieved through mechanical integration of the cement. Few mid-term results are available for newer cementless TKA designs that have used additive manufacturing (3-D printing) for component design. The purpose of this study is to present minimum 5-year clinical outcomes and implant survivorship of a specific cementless TKA using a novel 3-D printed tibial baseplate. This is a single institution registry review of the prospectively obtained data on 296 cementless TKA using a novel 3-D printed tibial baseplate with minimum 5-year follow-up. Outcomes were determined by comparing pre- and post-operative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) scores and pre- and post-operative 12 item Veterans RAND/Short Form Health Survey (VR/SF-12). Aseptic loosening as well as revision for any reason were the endpoints used to determine survivorship at 5 years.Introduction
Methods
The ideal type of total knee arthroplasty (TKA) prosthesis remains a debatable topic with many different options available. Uncemented TKA has been a viable option due to its decreased operating room (OR) time but also because of its proposed improved long term fixation. Unfortunately, in the past uncemented TKA was associated with increased blood loss. Surgical technique and perioperative treatments have changed since these original studies and tranexamic acid (TXA) has become the gold standard for TKA blood loss management. The objective of this study was to evaluate if there was a difference in hemoglobin and hematocrit change, along with blood loss volume during surgery between cemented and cementless TKA when modern blood loss techniques are utilized We retrospectively reviewed data from TKAs performed by three high volume surgeons between 2016 and 2019. We excluded bilateral TKA, revisions, hardware removal intraoperatively and other indications for TKA than primary OA. Power analysis determined 85 patients in both the cementless and cemented TKA groups. Patients were matched 1:1 for age, sex, BMI and surgeon. Use of TXA, intraoperative blood loss, differences in hemoglobin and hematocrit pre- and postoperatively days one, two, and three were recorded. Continuous variables were analyzed using T-tests and categorical variables were evaluated using Chi-squared tests.Introduction
Methods
Bone mineral density (BMD) is correlated with component migration and aseptic loosening after total knee arthroplasty (TKA). Older implant designs have demonstrated BMD loss up to 23% in the first 6 months after TKA, and continued to BMD decline at an average of 5% per year for as long as 2 years after TKA. The impact of component design and fixation method on BMD loss after TKA in modern implant designs has not been fully elucidated. The purpose of this study is to determine the effect of tibial tray thickness and fixation method (cemented versus cementless) on BMD loss patterns of the proximal tibia in two different modern TKA implant systems A prospective, nonrandomized, single center study of patients undergoing primary TKA by one of two surgeons was performed with four study cohorts: cemented DePuy Attune, cementless DePuy Attune, cemented Stryker Triathlon, cementless Stryker Triathlon. Target sample size was 80, with 20 per cohort based on adhoc power analysis. Exclusion criteria included: age over 75, BMI >40, inflammatory arthritis, previous knee surgery involving the femur, tibia or tibial bone, and diagnosis of osteopenia/osteoporosis. Implant fixation type was based on surgeon intraoperative assessment of patient bone quality. Demographic data was collected preoperatively. Dual Energy X-ray Absorptiometry (DEXA) Bone Density Monitoring was performed at 6 weeks and one year postoperatively. Bone mineral density was calculated from the DEXA scans for 4 zones for the tibia relative to the keel or central peg: anterior, posterior, medial and lateral. Results were reported as BMD at 1 year postoperatively as a percentage of BMD at 6 weeks postoperatively.Introduction
Methods
Manipulation under anesthesia (MUA) remains the gold standard to address restricted range of motion (ROM) within 3–6 months after primary total knee arthroplasty (TKA). However, there is little data on the outcomes of MUA with different types of anesthesia. We sought to compare the outcomes of patients undergoing MUA with intravenous (IV) sedation and neuraxial anesthesia. We identified 548 MUAs after primary TKA (136 IV sedation, 413 neuraxial anesthesia) at a single institution from 2016–2019. Mean age was 62 years and 349 patients (64%) were female. Mean body mass index was 32 kg/m2. The mean time from primary TKA to MUA was 10 weeks. Mean pre-MUA ROM was similar between each group; mean pre-MUA extension was 4.2° (p=0.35) and mean pre-MUA flexion was 77° (p=0.56). Patient demographics were statistically similar between both groups. We compared immediate complications, including fracture, extensor mechanism disruptions, and wound complications, Visual analogue pain scores (VAS), length of stay (LOS), and immediate and 3 month follow-up ROM between these groups.Introduction
Methods
Vancomycin is a commonly used antibiotic for prophylaxis in total joint replacement surgery. Several studies have reported superior local tissue concentration of vancomycin using intraosseous (IO) infusion compared with standard intravenous (IV) administration in total knee arthroplasty (TKA). We reviewed patients undergoing primary TKA who received IO vancomycin to a group receiving IV vancomycin. A retrospective review of 1038 patient who underwent primary TKA at our institution was performed from May 1, 2016 to May 1, 2019. This was a consecutive series of patients before and after we adopted this technique. IO vancomycin administration technique has been previously reported from our institution (500mg vancomycin in 200mL solution). Comparisons included preoperative and postoperative creatinine values, adverse reaction to vancomycin, tourniquet time, re-operation rates, periprosthetic joint infection rate at 1 year.Introduction
Methods
The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors. Data were prospectively collected on all patients who underwent total or unicompartmental knee arthroplasty at a between July 2015 and June 2018. Cohort 1 (n = 5,958) was utilized to develop models for LOS and 90 day readmission. Cohort 2 (n = 2,391, surgery date 2015 to 2017) was utilized to develop models for one-year improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, KOOS function score, and KOOS quality of life (QOL) score. Model accuracies within the imputed data set were assessed through cross-validation with root mean square errors (RMSEs) and mean absolute errors (MAEs) for the LOS and PROMs models, and the index of prediction accuracy (IPA), and area under the curve (AUC) for the readmission models. Model accuracies in new patient data sets were assessed with AUC.Aims
Methods
The primary objective of this study was to compare migration of the cemented ATTUNE fixed bearing cruciate retaining tibial component with the cemented Press-Fit Condylar (PFC)-sigma fixed bearing cruciate retaining tibial component. The secondary objectives included comparing clinical and radiological outcomes and Patient Reported Outcome Measures (PROMs). A single blinded randomized, non-inferiority study was conducted including 74 patients. Radiostereometry examinations were made after weight bearing, but before hospital discharge, and at three, six, 12, and 24 months postoperatively. PROMS were collected preoperatively and at three, six, 12, and 24 months postoperatively. Radiographs for measuring radiolucencies were collected at two weeks and two years postoperatively.Aims
Methods
The James Lind Alliance aims to bring patients, carers, and clinicians together to identify uncertainties regarding care. A Priority Setting Partnership was established by the British Association for Surgery of the Knee in conjunction with the James Lind Alliance to identify research priorities related to the assessment, management, and rehabilitation of patients with persistent symptoms after knee arthroplasty. The project was conducted using the James Lind Alliance protocol. A steering group was convened including patients, surgeons, anaesthetists, nurses, physiotherapists, and researchers. Partner organizations were recruited. A survey was conducted on a national scale through which patients, carers, and healthcare professionals submitted key unanswered questions relating to problematic knee arthroplasties. These were analyzed, aggregated, and synthesized into summary questions and the relevant evidence was checked. After confirming that these were not answered in the current literature, 32 questions were taken forward to an interim prioritization survey. Data from this survey informed a shortlist taken to a final consensus meeting.Aims
Methods
The aim of this prospective multicentre study was to describe trends in length of stay and early complications and readmissions following unicompartmental knee arthroplasty (UKA) performed at eight different centres in Denmark using a fast-track protocol and to compare the length of stay between centres with high and low utilization of UKA. We included data from eight dedicated fast-track centres, all reporting UKAs to the same database, between 2010 and 2018. Complete ( > 99%) data on length of stay, 90-day readmission, and mortality were obtained during the study period. Specific reasons for a length of stay of > two days, length of stay > four days, and 30- and 90-day readmission were recorded. The use of UKA in the different centres was dichotomized into ≥ 20% versus < 20% of arthroplasties which were undertaken being UKAs, and ≥ 52 UKAs versus < 52 UKAs being undertaken annually.Aims
Methods
Unicompartmental knee arthroplasty (UKA) has become a popular method of treating knee localized osteoarthritis (OA). Additionally, the posterior cruciate ligament (PCL) is essential to maintaining the physiological kinematics and functions of the knee joint. Considering these factors, the purpose of this study was to investigate the biomechanical effects on PCL-deficient knees in medial UKA. Computational simulations of five subject-specific models were performed for intact and PCL-deficient UKA with tibial slopes. Anteroposterior (AP) kinematics and contact stresses of the patellofemoral (PF) joint and the articular cartilage were evaluated under the deep-knee-bend condition.Aims
Methods
The anterior cruciate ligament (ACL) is known to have a poor wound healing capacity, whereas other ligaments outside of the knee joint capsule such as the medial collateral ligament (MCL) apparently heal more easily. Plasmin has been identified as a major component in the synovial fluid that varies among patients. The aim of this study was to test whether plasmin, a component of synovial fluid, could be a main factor responsible for the poor wound healing capacity of the ACL. The effects of increasing concentrations of plasmin (0, 0.1, 1, 10, and 50 µg/ml) onto the wound closing speed (WCS) of primary ACL-derived ligamentocytes (ACL-LCs) were tested using wound scratch assay and time-lapse phase-contrast microscopy. Additionally, relative expression changes (quantitative PCR (qPCR)) of major LC-relevant genes and catabolic genes were investigated. The positive controls were 10% fetal calf serum (FCS) and platelet-derived growth factor (PDGF).Aims
Methods
To report mid- to long-term results of Oxford mobile bearing domed lateral unicompartmental knee arthroplasty (UKA), and determine the effect of potential contraindications on outcome. A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and the presence of full-thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated.Aims
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Although bone cement is the primary mode of fixation in total knee arthroplasty (TKA), cementless fixation is gaining interest as it has the potential of achieving lasting biological fixation. By 3D printing an implant, highly porous structures can be manufactured, promoting osseointegration into the implant to prevent aseptic loosening. This study compares the migration of cementless, 3D-printed TKA to cemented TKA of a similar design up to two years of follow-up using radiostereometric analysis (RSA) known for its ability to predict aseptic loosening. A total of 72 patients were randomized to either cementless 3D-printed or a cemented cruciate retaining TKA. RSA and clinical scores were evaluated at baseline and postoperatively at three, 12, and 24 months. A mixed model was used to analyze the repeated measurements.Aims
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This study aims to evaluate a new home medical stretching device called the Self Treatment Assisted Knee (STAK) tool to treat knee arthrofibrosis. 35 patients post-major knee surgery with arthrofibrosis and mean range of movement (ROM) of 68° were recruited. Both the STAK intervention and control group received standard physiotherapy for eight weeks, with the intervention group additionally using the STAK at home. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford Knee Scores (OKS) were collected at all timepoints. An acceptability and home exercise questionnaire capturing adherence was recorded after each of the interventions.Aims
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Proliferation, migration, and differentiation of anterior cruciate ligament (ACL) remnant and surrounding cells are fundamental processes for ACL reconstruction; however, the interaction between ACL remnant and surrounding cells is unclear. We hypothesized that ACL remnant cells preserve the capability to regulate the surrounding cells’ activity, collagen gene expression, and tenogenic differentiation. Moreover, extracorporeal shock wave (ESW) would not only promote activity of ACL remnant cells, but also enhance their paracrine regulation of surrounding cells. Cell viability, proliferation, migration, and expression levels of Collagen-I (COL-I) A1, transforming growth factor beta (TGF-β), and vascular endothelial growth factor (VEGF) were compared between ACL remnant cells untreated and treated with ESW (0.15 mJ/mm2, 1,000 impulses, 4 Hz). To evaluate the subsequent effects on the surrounding cells, bone marrow stromal cells (BMSCs)’ viability, proliferation, migration, and levels of Type I Collagen, Type III Collagen, and tenogenic gene (Aims
Methods
Total knee arthroplasty is an established treatment for knee osteoarthritis with excellent long-term results, but there remains controversy about the role of uncemented prostheses. We present the long-term results of a randomized trial comparing an uncemented tantalum metal tibial component with a conventional cemented component of the same implant design. Patients under the age of 70 years with symptomatic osteoarthritis of the knee were randomized to receive either an uncemented tantalum metal tibial monoblock component or a standard cemented modular component. The mean age at time of recruitment to the study was 63 years (50 to 70), 46 (51.1%) knees were in male patients, and the mean body mass index was 30.4 kg/m2 (21 to 36). The same cruciate retaining total knee system was used in both groups. All patients received an uncemented femoral component and no patients had their patella resurfaced. Patient outcomes were assessed preoperatively and postoperatively using the modified Oxford Knee Score, Knee Society Score, and 12-Item Short-Form Health Survey questionnaire (SF-12) score. Radiographs were analyzed using the American Knee Society Radiograph Evaluation score. Operative complications, reoperations, or revision surgery were recorded. A total of 90 knees were randomized and at last review 77 knees were assessed. In all, 11 patients had died and two were lost to follow-up.Aims
Methods
The Oswestry-Bristol Classification (OBC) was recently described as an MRI-based classification tool for the femoral trochlear. The authors demonstrated better inter- and intraobserver agreement compared to the Dejour classification. As the OBC could potentially provide a very useful MRI-based grading system for trochlear dysplasia, it was the aim to determine the inter- and intraobserver reliability of the classification system from the perspective of the non-founder. Two orthopaedic surgeons independently assessed 50 MRI scans for trochlear dysplasia and classified each according to the OBC. Both observers repeated the assessments after six weeks. The inter- and intraobserver agreement was determined using Cohen’s kappa statistic and S-statistic nominal and linear weights.Aims
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To compare time dependent functional improvement for patients with medial, respectively lateral knee osteoarthritis (OA) after treatment with opening wedge osteotomy relieving the pressure on the osteoarthritic part of the knee. In all, 49 patients (52 knees) with a mean age of 47 years (31 to 64) underwent high tibial osteotomies (HTO), and 24 patients with a mean age of 48 years (31 to 62) low femoral osteotomies (LFO) with opening wedge technique due to medial, respectively lateral knee OA with malalignment. All osteotomies were stabilized with a Puddu plate and bone grafting performed in the same time period (2000 to 2008). The patients were evaluated by the Knee Injury and Osteoarthritis Outcome Score (KOOS) pre-operatively and at six months, and at one, two, five, and ten years postoperatively. The knee OA was graded according to the Ahlbäck and Kellgren-Lawrence radiological scoring systems.Aims
Methods
An algorithm to determine the constitutional alignment of the lower limb once arthritic deformity has occurred would be of value when undertaking kinematically aligned total knee arthroplasty (TKA). The purpose of this study was to determine if the arithmetic hip-knee-ankle angle (aHKA) algorithm could estimate the constitutional alignment of the lower limb following development of significant arthritis. A matched-pairs radiological study was undertaken comparing the aHKA of an osteoarthritic knee (aHKA-OA) with the mechanical HKA of the contralateral normal knee (mHKA-N). Patients with Grade 3 or 4 Kellgren-Lawrence tibiofemoral osteoarthritis in an arthritic knee undergoing TKA and Grade 0 or 1 osteoarthritis in the contralateral normal knee were included. The aHKA algorithm subtracts the lateral distal femoral angle (LDFA) from the medial proximal tibial angle (MPTA) measured on standing long leg radiographs. The primary outcome was the mean of the paired differences in the aHKA-OA and mHKA-N. Secondary outcomes included comparison of sex-based differences and capacity of the aHKA to determine the constitutional alignment based on degree of deformity.Aims
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While patients with psychological distress have poorer short-term outcomes after total knee arthroplasty (TKA), their longer-term function is unknown. We aimed to 1) assess the influence of preoperative mental health status on long-term functional outcomes, quality of life, and patient satisfaction; and 2) analyze the change in mental health after TKA, in a cohort of patients with no history of mental health disorder, with a minimum of ten years’ follow-up. Prospectively collected data of 122 patients undergoing primary unilateral TKA in 2006 were reviewed. Patients were assessed pre- and postoperatively at two and ten years using the Knee Society Knee Score (KSKS) and Function Score (KSFS); Oxford Knee Score (OKS); and the Mental (MCS) and Physical Component Summary (PCS) which were derived from the 36-Item Short-Form Health Survey questionnaire (SF-36). Patients were stratified into those with psychological distress (MCS < 50, n = 51) and those without (MCS ≥ 50, n = 71). Multiple regression was used to control for age, sex, BMI, Charlson Comorbidity Index (CCI), and baseline scores. The rate of expectation fulfilment and satisfaction was compared between patients with low and high MCS.Aims
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Cementless unicompartmental knee arthroplasty (UKA) has advantages over cemented UKA, including improved fixation, but has a higher risk of tibial plateau fracture, particularly in Japanese patients. The aim of this multicentre study was to determine when cementless tibial components could safely be used in Japanese patients based on the size and shape of the tibia. The study involved 212 cementless Oxford UKAs which were undertaken in 174 patients in six hospitals. The medial eminence line (MEL), which is a line parallel to the tibial axis passing through the tip of medial intercondylar eminence, was drawn on preoperative radiographs. Knees were classified as having a very overhanging medial tibial condyle if this line passed medial to the medial tibial cortex. They were also classified as very small if a size A/AA tibial component was used.Aims
Methods
Our objective is to describe our early and mid-term results with the use of a new simple primary knee prosthesis as an articulating spacer in planned two-stage management for infected knee arthroplasty. As a second objective, we compared outcomes between the group with a retained first stage and those with a complete two-stage revision. We included 47 patients (48 knees) with positive criteria for infection, with a minimum two-year follow-up, in which a two-stage approach with an articulating spacer with new implants was used. Patients with infection control, and a stable and functional knee were allowed to retain the initial first-stage components. Outcomes recorded included: infection control rate, reoperations, final range of motion (ROM), and quality of life assessment (QoL) including Western Ontario and McMaster Universities osteoarthritis index, Knee Injury and Osteoarthritis Outcome Score, Oxford Knee Score, 12-Item Short-Form Health Survey questionnaire, and University of California Los Angeles (UCLA) activity score and satisfaction score. These outcomes were evaluated and compared to additional cohorts of patients with retained first-stage interventions and those with a complete two-stage revision. Mean follow-up was 3.7 years (2.0 to 6.5).Aims
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The purpose of this study was to explore the correlation between femoral torsion and morphology of the distal femoral condyle in patients with trochlear dysplasia and lateral patellar instability. A total of 90 patients (64 female, 26 male; mean age 22.1 years (SD 7.2)) with lateral patellar dislocation and trochlear dysplasia who were awaiting surgical treatment between January 2015 and June 2019 were retrospectively analyzed. All patients underwent CT scans of the lower limb to assess the femoral torsion and morphology of the distal femur. The femoral torsion at various levels was assessed using the a) femoral anteversion angle (FAA), b) proximal and distal anteversion angle, c) angle of the proximal femoral axis-anatomical epicondylar axis (PFA-AEA), and d) angle of the AEA–posterior condylar line (AEA-PCL). Representative measurements of distal condylar length were taken and parameters using the ratios of the bianterior condyle, biposterior condyle, bicondyle, anterolateral condyle, and anteromedial condyle were calculated and correlated with reference to the AEA, using the Pearson Correlation coefficient.Aims
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