Early discharge after total joint arthroplasty has started to gain acceptance in select academic centers. The purpose of this study was to compare the risk of readmission of Medicare patients discharged one day after total knee arthroplasty (TKA), versus those discharged two or three days after surgery. Our hypothesis was that patients with length of stay (LOS) of one day would not have a higher risk of readmission in a community setting. A hospital impatient database was queried for all unilateral, primary total knee replacements performed on patients 65 years or older from January 1, 2013 to December 31, 2014. A total of 1,117 patients discharged the day after TKA (reduced LOS) were compared with 947 patients discharged POD #2 or 3 (traditional LOS). All cases were performed at a community-based joint replacement center with rapid recovery protocols. Discharge timing and disposition were based on established functional benchmarks judged by physical therapy. The main outcome measure was all-cause 30-day readmissions. Multivariate logistic regression was used to calculate odds ratio for all cause 30-day readmission for reduced versus traditional LOS while controlling for age, gender, race, diabetes mellitus, ASA score (less than 3 versus 3 or greater), discharge disposition (home versus rehab).INTRODUCTION
METHODS
Rapid recovery protocols after joint replacement have been implemented widely to decrease hospital length of stay (LOS). Minimally-invasive total knee arthroplasty (MIS-TKA) may facilitate rapid recovery for patients. Increased complications and LOS have been documented in morbidly obese TKA patients. The objective of the current study was to retrospectively evaluate the impact of morbid obesity on MIS-TKA patients. We conducted a retrospective chart review on patients that underwent MISTKA at a high volume orthopedic center between August 2012 and September 2015 (N = 4173). All surgeries were performed by one of six fellowship trained surgeons utilizing the same implant. MISTKA was performed utilizing a mid-vastus approach under tourniquet. All patients experienced rapid recovery protocols utilizing multi-modal pain management pathways, same day physical therapy, and absence of CPM machines. We evaluated patient age, gender, operative time, LOS, and 90-day readmission for morbidly obese (BMI≥40; n = 597), and non-morbidly obese (BMI<40; n = 3576) patients. Statistical analysis was conducted using Minitab 16 Statistical Software.Introduction
Methods
Liposomal bupivacaine has been shown to be effective in managing post-operative pain in hallux valgus and hemorrhoid surgery. However, non-industry-supported and well-powered randomized studies evaluating its efficacy in Total Knee Arthroplasty (TKA) are lacking. Our hypothesis was that liposomal bupivacaine would not decrease post-operative visual analog pain scores (VAS) or narcotic consumption in the acute post-operative period. Two hundred seven consecutive patients were enrolled into a single-blinded prospective randomized study. We included patients undergoing unilateral TKA by five fellowship-trained surgeons with a diagnosis of osteoarthritis, rheumatoid arthritis, or post-traumatic arthritis. Patients were excluded for any other diagnosis necessitating TKA, allergy to the medications, or pre-operative opiate use. Participants received standardized pain management, anesthesia, and physical therapy. Patients were randomized intra-operatively to one of three groups: an intra-articular (IA) injection of bupivacaine and morphine at the conclusion of the procedure, a peri-articular (PA) injection of a bupivacaine and morphine, or a PA injection of liposomal bupivacaine. Post-operative pain VAS and mean morphine equivalents (MME) consumed were recorded and compared utilizing analysis of variance (ANOVA). A power analysis demonstrated that 159 patients were needed for 80% power to detect a 25% difference in VAS or MME.Introduction
Methodology
Rapid recovery protocols (RRP) for joint replacements have been shown to improve efficiency, reduce costs, and minimize adverse outcomes in academic health systems. The purpose of this study is to evaluate if RRP can be safely implemented in a community health system for total knee arthroplasty. This study used a retrospective cohort of 3,608 patients who underwent primary unilateral total knee arthroplasty from January 1, 2013 to December 31, 2014. 60 Patients were excluded because data or surgery could not be verified: BMI less than 18.5 or greater than 60 kg/m∘2 or if the surgical time was less than 45 seconds or greater than 180 minutes, and bilateral surgery. Data was obtained from querying the health system's inpatient database containing information for all joint replacements within the system. Patients were compared in two groups: those who received a RRP after surgery versus those who received traditional post-op care. The main outcome measure was all-cause 30-day readmissions. Multivariate logistic regression was used to calculate the odds for all-cause 30-day readmission for patients who received RRP versus traditional care when controlling for age, gender, race, insurance status (Medicare versus no Medicare), obesity, diabetes, renal disease, tobacco use, and ASA score (less than 3 versus 3 or greater).Introduction
Methods
The aim of this study was to quantify mid-flexion laxity in a total knee arthroplasty with an elevated joint line, as compared to a native knee and a TKA with joint line maintained. Our hypothesis was joint line elevation of 4mm would increase coronal plane laxity throughout mid-flexion in a pattern distinct from the preoperative knee or in a TKA with native joint line. Six fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilised implant (APEX PS, OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, the flexion and extension gaps were balanced using navigation, and a 4mm recut was made in the distal femur. The remaining femoral cuts were made, the femoral component was downsized by resecting an additional 4mm of bone off the posterior condyles, and the polyethylene was increased by 4mm to create a situation of a well-balanced knee with an elevated joint line. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90(of flexion, when applying a standardised varus/valgus load of 9.8Nm across the knee using a 4kg spring-load located at 25cm distal to the knee joint line. Laxity was also measured in the native knee, as well as the native knee after a standard approach during TKA which included a medial release. Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardised varus and valgus stress at 0, 30, 45, 60 and 90(.Introduction
Methods
The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs in a well-balanced knee with an elevated joint line of 4 mm. In the setting an elevated joint line, we hypothesized that we would observe an increased varus and/or valgus laxity throughout mid flexion. After obtaining IRB approval, nine fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS, OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, the flexion and extension gaps were balanced using navigation, and a 4 mm recut was made in the distal femur. The remaining femoral cuts were made, the femoral component was downsized by resecting an additional 4 mm of bone off the posterior condyles, and the polyethylene was increased by 4 mm to create a situation of a well-balanced knee with an elevated joint line. Real implants were used in the study to eliminate any inherent error or laxity in the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times. Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm joint line elevation with an otherwise well balanced knee.Introduction
Methods
The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs with a loose extension gap in TKA. In the setting of a loose extension gap, we hypothesized that although full extension is achieved, a loose extension gap will ultimately lead to increased varus and/or valgus laxity throughout mid flexion. After obtaining IRB approval, six fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, and the flexion and extension gaps were balanced using navigation, a 4 mm distal recut was made in the distal femur to create a loose extension gap (using the same thickness of polyethylene as the well-balanced case). Real implants were used in the study to eliminate error in any laxity inherent to the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line. (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times. Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm recut in the distal femur creating a loose extension gap.Introduction
Methods
Ceramic femoral heads have superior scratch resistant with better wettability and improved wear characteristics compared to metal heads in the laboratory setting. The objective of this study was to compare long-term in vivo wear rates of ceramic and metal femoral heads against conventional polyethylene articulation with cementless stems in young, active patients. Thirty-one matched pair of alumina and metal (Cr-Co) femoral heads against conventional polyethylene in young patients (between 45 and 65 years old) were analyzed for wear and failures for mechanical reasons. The match was based on gender and age at the time of surgery. All procedures were performed between June 1989 and May 1992 by a single surgeon via posterolateral approach, using cementless RB (Ranawat-Bernstein) stems, HG II (Harris-Galante) cups, 4150 conventional polyethylene and 28 mm femoral heads. Hospital for Special Surgery (HSS) hip score was used for clinical analysis. Wear measurements were performed between the initial anteroposterior standing pelvis radiographs, at a minimum of one year after the index procedure to eliminate the effect of bedding-in period, and the latest follow-up. Two independent observers analyzed polyethylene wear rates using the computer-assisted Roman 1.70 software. In revision cases, the wear rates were calculated from radiographs prior to revision surgery. A pair student t test was performed to analyze the statistical difference. Two-tailed ρ values less than 0.05 were considered statistically significant.Introduction
Materials and Methods
Ceramic femoral heads have proven to be more scratch resistant with better wettability and improved wear characteristics compared to metal heads in the laboratory setting. The objective of this study was to compare long-term survivorship and in vivo wear rates of ceramic and metal femoral heads against conventional polyethylene articulation in young patients. Thirty-one matched pair of alumina and metal femoral heads against conventional polyethylene in young patients (≤ 65 years) were analyzed for wear and failures for mechanical reasons. The match was based on gender and age at the time of surgery. All procedures were performed between June 1989 and May 1992 by a single surgeon via posterolateral approach, using non-cemented RB (Ranawat-Bernstein) stems, HG II (Harris-Galante) cups, 4150 conventional polyethylene and 28mm femoral heads. Hospital for Special Surgery (HSS) hip score was used for clinical analysis. Wear measurements were performed between the initial anteroposterior standing pelvis radiographs, at a minimum of one year after the index procedure to eliminate the effect of bedding-in period, and the latest follow-up. Two independent observers analyzed polyethylene wear rates using the computer-assisted Roman 1.70 software. In revision cases, the wear rates were calculated from radiographs prior to revision surgery. A pair student t test was performed to analyze the statistical difference. Two-tailed ρ values less than 0.05 were considered statistically significant.Introduction
Materials and Methods
The optimal goal for cup positioning in hip arthroplasty in individual patients is affected by many factors including surgical exposure, femoral anteversion, and pelvic tilt. Some navigation systems ignore pelvic tilt and are based strictly on the anterior pelvic plane while others incorporate pelvic tilt, as measured in the supine position on the operating table. Neither approach incorporates knowledge of preoperative spino-pelvic flexibility or predictions of the change in spino-pelvic attitude or flexibility following surgery. While prior studies have shown little change in pelvic tilt postoperatively, one recent study based on gait analysis, suggested that changes in pelvic tilt are not predictable. The current study aims to assess changes in pelvic tilt following surgery. 24 patients, 12 male and 12 female, underwent THA using CT-based navigation. Each patient had supine and standing AP pelvis radiographs both pre-operatively and at a minimum of 1 year post-operatively. Pelvic tilt on each radiograph was measured using a noncommercial two-dimensional/three-dimensional matching application. (HipMatch; Institut for Surgical Technology and Biomechanics, Bern, Switzerland). This software application uses a fully auto- mated registration procedure that can match the three- dimensional model of the preoperative CT with the projected pelvis on a postoperative radiograph. This method has been validated and for measurement of cup position for example showed a mean accuracy of 1.7° +/− 1.7° (rang-4.6° to 5.5°) in the coronal plane and 0.9° +/− 2.8° (rang-5.2° to 5.7°) in the sagittal plane compared with postoperative CT measurements. The software showed a good consistency with an intraclass correlation coefficient (ICC) for inclination of 0.96 (95% confidence interval [CI]: 0.93 to 0.98) and for anteversion of 0.95 (95% CI: 0.91 to 0.98). A good reproducibility and reliability for both inclination and anteversion was found with an ICC ranging from 0.95 to 0.99. No systematic errors in accuracy were detected with the Bland- Altman analysis. Using the HipMatch 2D/3D application, changes in pelvic tilt before and after surgery were assess in both the supine and standing positions.Introduction
Methods
