Total hip replacement (THA) is among the most common and highest total spend elective operations in the United States. However, up to 7% of patients have 90-day complications after surgery, most frequently joint dislocation that is related to poor acetabular component positioning. These complications lead to patient morbidity and mortality, as well as significant cost to the health system. As such, surgeons and hospitals value navigation technology, but existing solutions including robotics and optical navigation are costly, time-consuming, and complex to learn, resulting in limited uptake globally. Augmented reality represents a navigation solution that is rapid, accurate, intuitive, easy to learn, and does not require large and costly equipment in the operating room. In addition to providing cutting edge technology to specialty orthopedic centers, augmented reality is a very attractive solution for lower volume and smaller operative settings such as ambulatory surgery centers that cannot justify purchases of large capital equipment navigation systems.Problem
Solution
Although multifunctional delivery systems can potentially improve safety and efficacy of therapeutic protein delivery in the biological treatment of injured tissues, ability to track and manipulate protein delivery systems in vivo to ensure localization at the treatment site is still a concern. We hypothesized that incorporating superparamagnetic iron oxide (SPIO) into calcium phosphate (CaP) coated β-tricalcium phosphate (β-TCP) microparticles would allow for Magnetic Resonance Imaging (MRI) based tracking in vivo and SPIO incorporation would not impact the biological activity of proteins delivered with these microparticles. To address the efficacy and limitations in therapeutic protein delivery, a CaP coated microparticle which incorporates superparamagnetic iron oxide (SPIO-CaP-MP) was created and used in a rat knee medial collateral ligament. The system has trifunctional properties: (1) it is trackable using magnetic resonance imaging (MRI), (2) it can be manipulated with a magnetic field, (3) it can release active proteins in the injury site. SPIO-Ca-MPs were formed on β-tricalcium phosphate cores. Using MRI, SPIO-CaP-MPs were visible in T2 weighted sequences as an area of hypointesive signal. SPIO-CaP-MPs could be visualized and remained localized for at least 15 days after injection into the medial collateral ligament. Recombinant human basic fibroblast growth factor delivered with SPIO-CaP-MPs stimulated the proliferation of human dermal fibroblasts. Finally, SPIO-CaP-MPs could be localized to a bar magnet when suspended in solution. Taken together, these results suggest that SPIO-CaPMPs could be useful for protein delivery applications in the treatment of ligament injury that may benefit from externally controlled localization and MRI-based tracking.
In the United States, the Centers for Medicare and Medicaid Services consider rates of unplanned hospital readmissions to be indicators of provider quality. Understanding the common reasons for readmission following total joint arthroplasty will allow for improved standards of care and better outcomes for patients. The current study seeks to evaluate the rates, reasons, and Medicare costs for readmission after total hip and total knee arthroplasty. This study used the Limited Data Set (LDS) from the Centers for Medicare and Medicaid Services (CMS) to identify all primary, elective Total Knee Arthroplasties (TKA) and Total Hip Arthroplasties (THA) performed from January 2013 through June 2016. The data were limited to Diagnosis-Related Group (DRG) 470, which is comprised of major joint replacements without major complications or comorbidities. Readmissions were classified by corresponding DRG. Readmission rates, causes, and associated Medicare Part A payments were aggregated over a ninety-day post-discharge period for 804,448 TKA and 409,844 THA.INTRODUCTION
METHODS
Patient demand for hip and knee arthroplasty continues to rise. Information sources providing data on the volume and cost of Medicare total joint arthroplasty by hospital are of use to patients and healthcare professionals. Data have demonstrated that higher volume surgeons are associated with lower cost, morbidity, and mortality. The current study assesses if the same is true for hospitals. The Limited Data Set (LDS) from the Centers for Medicare and Medicaid (CMS) were used for this study. All elective, DRG 470 Total Hip Arthroplasties (THA) reported by CMS from the first quarter of 2013 through the second quarter of 2016 were included. Volume and part A Medicare payments over a 90-day period for the 20 highest volume hospitals in the US were analyzed. Cost associated with initial hospital stay and post discharge skilled nursing, home health, long term acute care, inpatient rehabilitation facilities, and readmission was aggregated and analyzed. For each episode, demographic information (age, sex, and race), geographic location, and Elixhauser comorbidities were calculated to control for major confounding factors in the regression.Introduction
Methods
While total hip arthroplasty is considered to be one of the most cost-effective medical interventions, the total cost of care for a population patients treated by THR can present a significant burden on the payer, whether it be an employer, private insurer or government. Data on the true cost of care has rarely been made available to the treating physician. Such lack of information makes comprehensive management difficult. Bundled payment models of care require knowledge of all costs associated with the care of our patients and opens new opportunity for analysis to improve management and outcomes. The current study assess the influence of surgical technique on total cost of care for total hip arthroplasty. Payment data for 341 patients who underwent total hip arthroplasty at a single institution from June 1st, 2011 to October 31st, 2014 were analyzed. Each procedure was performed using either the superior, anterior, or posterior exposure. The superior exposure was performed with femoral head excision and without dislocation of the hip. The data were analyzed for total cost, inpatient cost, inpatient physician cost, readmission cost, skilled nursing facility cost, and home healthcare agency cost among the different approaches.Introduction
Methods
Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago1. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation by comparing the orientation of acetabular components revised due to recurrent instability and to a series of stable hip replacements. Cup orientation in 21 hips revised for recurrent instability was measured using CT. These hips were compared to a group of 115 stable hips measured using the same methods. Femoral anteversion in the stable hips was also measured. Images to assess femoral anteversion in the unstable group were not available. An application specific software modules was developed to measure cup orientation using CT (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). The cup orientation was determined by first identifying Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was calculated according to Murray's definitions of operative anteversion and operative inclination2. Both absolute cup position relative to the APP and tilt-adjusted cup position3 were calculated.Introduction
Methods
Navigation of acetabular component orientation is still not commonly performed despite repeated studies that show that more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned1. The current study uses postoperative CT to assess the accuracy of a smart mechanical navigation instrument system for cup alignment. Thirty seven hip replacements performed using a smart mechanical navigation device (the HipXpert System) had post-operative CT studies available for analysis. These post-operative CT studies were performed for pre-operative planning of the contralateral side, one to three years following the prior surgery. An application specific software module was developed to measure cup orientation using CT (HipXpert Research Application, Surgical Planning Associates Inc., Boston, Massachusetts). The method involves creation of a 3D surface model from the CT data and then determination of an Anterior Pelvic Plane coordinate system. A multiplaner image viewer module is then used to create an image through the CT dataset that is coincident with the opening plane of the acetabular component. Points in this plane are input and then the orientation of the cup is calculated relative to the AP Plane coordinate space according to Murray's definitions of operative anteversion and operative inclination. The actual cup orientation was then compared to the goal of cup orientation recorded when the surgery was performed using the system for acetabular component alignment.Introduction
Patients and Methods
Patients less than 60 years old have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population. For the six year period from May 1999 to March 2005, 278 hip replacements in 244 patients less than 60 yeas of age at the time of surgery were performed using alumina ceramic-ceramic bearings. All hips had uncemented titanium femoral and acetabular components. The ceramic liner was fixed to the shell with an 18-degree flush-mounted taper design. Patients were followed clinically and radiographically. Attempts were made to contact all patients who had not been seen in the prior 3 years. Of the 278 hips, 17 hips (16 patients) remain lost to follow-up, leaving 261 hips (228 patients; 155 hips in men, 106 hips in women) for assessment. Mean age of the patients was 46.2 years at the time of surgery (range 17.8 to 59.9 years). 17% of hips had at least one previous hip surgery. Mean time following surgery was 9.75 years (range 2 to 16.8 years).INTRODUCTION
METHODS
Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. The current study assesses the validity of intraoperative assessment using a specialized software to analyze intraoperative radiographs. Cup orientation as measured on intraoperative radiography using the RadLink Galileo Positioning System was assessed in 10 patients. These radiographs were measured by personnel trained to support the system. The results were compared to cup orientation measured by CT. Cup orientation on CT was measured by first identifying the Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was then calculated. The same definition of cup orientation was used for both methodologies.Introduction
Methods
Evolving payment models create new opportunities for assessment of patient care based on total cost over a defined period of time. These models allow for analyses of economic data that was previously unavailable and well beyond our familiar studies which typically include length of stay, surgical complications, and post-operative clinical and radiographic assessments. In the United States, the new Federal program entitled The total reimbursement for services performed following primary THA for patients insured by Medicare was analyzed for a group of patients at a single institution during the fiscal years of 2013 and 2014. The population included data on 356 patients who had surgery performed by seven surgeons who used the same pre-operative education, OR, PACU, PT, nursing, and case management. A total of 38 “pre-selected” patients underwent THA by an anterior exposure, 219 had surgery performed by a posterior exposure, and 99 had surgery performed by the superior exposure utilizing mechanical surgical navigation (HipXpert System, Surgical Planning Associates, Boston, MA). Reimbursement for all in-patient and out-patient services performed over the initial 90-day period from sugeical admission was compared across surgical techniques. Reimbursement includes the sum of all payments including the hospital, physicians, skilled nursing facilities, home care, out-patient care, and readmission.INTRODUCTION
METHODS
Navigation of acetabular component orientation is still not commonly performed despite repeated studies that show that more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned1. The current study uses postoperative CT to assess the accuracy of a smart mechanical navigation instrument system for cup alignment. Twenty nine hip replacements performed using the HipXpert Navigation System had post-operative CT studies available for analysis. These post-operative CT studies were performed for pre-operative planning of the contralateral side, one to three years following the prior surgery. The patients included 17 men and 11 women. An application specific software module was developed to measure cup orientation using CT (HXR Application 1.3 Surgical Planning Associates Inc., Boston, Massachusetts). The method involves creation of a 3D surface model from the CT data and then determination of an Anterior Pelvic Plane coordinate system. A multiplaner image viewer module is then used to create an image through the CT dataset that is coincident with the opening plane of the acetabular component. Points on this plane are input and then the orientation of the cup is calculated relative to the AP Plane coordinate space according to Murray's definitions of operative anteversion and operative inclination. The actual cup orientation was then compared to the goal of cup orientation recorded when the surgery was performed using the HipXpert navigation system for acetabular component alignment.Introduction
Patients and Methods
Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago1. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation by comparing the orientation of acetabular components revised due to recurrent instability and to a series of stable hip replacements. Cup orientation in 30 hips revisedin 27patients for recurrent instability was measured using CT. These hips were compared to a group of 115 stable hips measured using the same methods. Femoral anteversion in the stable hips was also measured. Images to assess femoral anteversion in the unstable group were not available. An application specific software modules was developed to measure cup orientation using CT (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). The cup orientation was determined by first identifying Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was calculated according to Murray's definitions of operative anteversion and operative inclination2. Both absolute cup position relative to the APP and tilt-adjusted cup position3 were calculated.INTRODUCTION
METHODS
Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation. We assessed the orientation of acetabular components revised due to recurrent instability and compared the results to a series of stable hip replacements.BACKGROUND
PURPOSE
Young patients (< 50 years old) have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population. Between August 1999 and December 2007, 220 total hip arthroplasties in 191 patients under 50 years of age at the time of surgery were performed using alumina ceramic-ceramic bearings as part of a prospective, non-randomized study. All patients received uncemented acetabular components with flush-mounted acetabular liners using an 18 degree taper, and uncemented femoral components. The average patient age at the time of surgery was 42.1 ±7.2 years (range: 17.4 years to 49.9 years), and the average time to follow-up was 10.1 ±2.4 years (range: 4.2 years to 15.2 years). We evaluated implant-related complications and performed Kaplan-Meier analyses to determine survivorship of the THA components with revision for any reason as the endpoint.INTRODUCTION
METHODS
Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. A recent study measuring cup orientation on conventional radiodiographs demonstrated an incidence of cup malpositioning of 50% according to the safe zone that they defined 1,2. A prior study of 105 conventionally placed cups using CT demonstrated a cup malpositioning incidence of 74%3. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT. CT studies of 123 hips in 119 patients with total hip arthroplasties performed using conventional techniques were used for this study. The indications for the CT studies were for CT-based surgical navigation of the contralateral side or for assessment of periprosthetic osteolysis. An application specific software modules was developed to measure cup orientation using CT (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). The cup orientation was determined by first identifying Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was calculated according to Murray's definitions of operative anteversion and operative inclination. Since these studies including images through the femoral condyles, femoral anteversion could be measured on these hips as well (Osirix v5.6, Pixmeo SARL, Bernex, Switzerland).Introduction
Methods
Cup malposition leads to increased incidences of dislocation, impingement, wear, and revision. The HipSextant navigation system is a smart mechanical navigation device designed to indicate correct cup orientation at surgery. The current study assesses the effect of deliberately mis-docking the device on clinical accuracy. Ten patients (5 men and 5 women) presenting for total hip arthroplasty were assessed. Planning for the HipSextant Navigation System (Surgical Planning Associates, Inc., Boston, MA) was performed as usual. This is done by first creating a 3D surface model from CT imaging, establishing an Anterior Pelvic Plane coordinate system, and then creating a patient-specific HipSextant coordinate system. This coordinate system is defined by three points. The first point, called the basepoint, is located just behind the posterior wall of the acetabulum a fixed distance above the infracotyloid notch. The second point is located on the lateral aspect of the anterior superior iliac spine. The third point is located on the surface of the ilium and equally distant from the other two points. These three points define a patient-specific coordinate system that is known relative to the APP. Clinically, the instrument is then docked according to the plan and two protractors on the top of the instrument allow a direction indicator to point in the direction of desired cup orientation. For each of the hips, after the HipSextant plan was created (Figure 1), two additional plans were created: one where the basepoint was docked 5 mm closer to and one 5 mm further from the infracotyloind notch. The effect of the deliberate mis-docking was measured in degrees of operative anteversion and operative inclination.Introduction:
Methods:
Wear, wear-associated osteolysis, and instability are the most common reasons for revision total hip arthroplasty. These failures have been shown to be associated with acetabular component malpositioning. However, optimal acetabular component orientation on a patient-specific basis is currently unknown. The current study uses CT to assess acetabular orientation in a group of unstable hips as compared to a control group of stable hips. Our institutional database of CT studies performed in the region of the hip beginning in February of 1998 (41,975 CT studies) was compared against our institutional database of revision total hip arthroplasties beginning in August of 2003 (2262 Revision THA) to identify CT studies of any hip treated for recurrent instability by revision of the acetabular component. Twenty hips in 20 patients with suitable CT studies were identified for the study group. Our control group consisted of 99 hips in 93 patients who had CT studies either for computer-assisted surgery on the contralateral side or for assessment of osteolysis. Using the CT data, the AP plane (APP) was defined, supine pelvic tilt was measured, and cup orientation was calculated by fitting a best fit plane to 6 points on the rim of the acetabular component. Cup orientation was calculated in degrees of operative anteversion and operative inclination according to the definitions of Murray. Both absolute cup position relative to the APP and tilt-adjusted cup position1 were calculated.Introduction:
Methods:
Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. A recent study measuring cup orientation on conventional radiodiographs demonstrated an incidence of cup malpositioning of 50% according to the safe zone that they defined1,2. A prior study of 105 conventionally placed cups using CT demonstrated a cup malpositioning incidence of 74%3. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT. We have performed CT-based navigation of hip arthroplasty and revision arthroplasty on a routine basis since 2003 and also use CT imaging to quantify periprosthetic osteolysis. In our image database from these, we have identified 98 hips and y patients who had a previously conventionally-placed cup on CT imaging. For each hip, cup orientation was determined in operative anteversion and operative inclination (according to the definitions of Murray) using an application specific software application (HipSextant Research Application 1.0.7, Surgical Planning Associates Inc., Boston, Massachusetts). This application allows for determination of the Anterior Pelvic Plane coordinates from a 3D surface model. A multiplanar reconstruction module allows for creation of a plane parallel with the opening plane of the acetabulum and subsequent calculation of plane orientation in the AP Plane coordinate space.Introduction:
Methods:
While more than ½ of acetabular components placed during hip arthroplasty are significantly malpositioned, traditional surgical navigation and robotoics have not been widely adopted. This may be due to the additional time, expense, and complexity associated with this technology. As an alternative, smart mechanical navigation instruments, adjusted on a patient-specific basis, have been introduced to address the problem of cup malorientation. The current study assesses the accuracy of acetabular component alignment using a mechanical navigation instrument. The acetabular component was aligned in 58 consecutive hips in 58 patients using the HipSextant Mechanical Navigation System (Surgical Planning Associates, Inc. Boston, MA). The technique involves using a patient-specific plan and associated software. In planning for surgery, CT data are used to create a 3D model and to define the anterior pelvic plane (APP). A patient-specific HipSextant docking coordinate system is then determined by three points: one just behind the posterior acetabular rim, a second on the lateral side of the ASIS, and a third on the surface of the ilium (Figure 1). The HipSextant itself has two adjustable orthogonal protractors (in-plane and off-plane angle) and two adjustable arms so that the instrument is adjusted for each patient based on their specific anatomy. The instrument docks directly to the pelvis so the recommended orientation of the acetabular component is based on the actual position of the pelvis at the time of component implantation. A direction indicator points in the direction of the planned cup orientation (Figure 2). Cup alignment was further enhanced with the use of a parallel guide to improve parallel visualization (Figure 3). Postoperative cup orientation was measured using a validated two-dimensional/three-dimensional matching method [3,5].Background:
Patients and Methods:
Conventional methods of aligning the acetabular component during hip arthroplasty and hip resurfacing often rely upon anatomic information available to the surgeon. Such anatomical information includes the transverse acetabular ligament and the locations of the pubis, ischium and ilium. The current study assesses the variation in orientation of the plane defined by the pubis, ischium and ilium on a patient-specific basis as measured by CT. To assess the reliability of anatomical landmarks in surgery, we assessed 54 hips in 51 patients (32 male, 22 female) who presented for CT-based surgical navigation of total hip arthroplasty. The HipSextant Research Application (version 1.0.7, Surgical Planning Associates Inc., Boston, Massachusetts) was used to perform the calculations. This application allows for determination of the Anterior Pelvic Plane coordinates from a 3D surface model. Standardized points on the ilium, ischium, and pubis were entered. These three points defined a plane and the orientation of the plane in the AP Plane coordinate system was calculated in degrees of operative anteversion and operative inclination according to the definitions of Murray1.Introduction:
Methods:
