Periprosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty. While research has focused on developing better tests for disease diagnosis, treatment options have stayed relatively constant over the years with high failure rates ranging from 30%–50% and are due in part to the protective biofilm produced by some bacterial species. Current treatment options are compromised by the presence of biofilm, emphasizing the need for novel treatment strategies to be developed. Our group has developed a novel treatment (PhotothermAA) which has demonstrated Rabbits were fitted with a titanium implant into the tibial plateau and inoculated with 5×106 CFU Xen36 (luminescent Aim
Method
Studies have shown that as many as 1 in 5 patients is dissatisfied following total knee replacement (TKA). There has also been a large reported disparity between surgeon and patient perception of clinical “success”. It has long been shown that surgeon opinion of procedural outcomes is inflated when compared with patient-reported outcomes. Additionally, TKA recipients have consistently reported higher pain levels, greater inhibition of function, and lower satisfaction than total hip replacement (THA) recipients. It is imperative that alternative methods be explored to improve TKA patient satisfaction. Therefore, the purpose of this study was to determine whether or not patients with a balanced TKA, as measured using intraoperative sensors, exhibit better clinical outcomes. 310 patients scheduled for TKA surgery were enrolled in a 6 center, randomized controlled trial, resulting in two patient groups: a sensor-guided TKA group and a surgeon-guided TKA group. Intraoperative load sensors were utilized in all cases, however in one group the surgeon used the feedback to assist in balancing the knee and in the other group the surgeon balanced without load data and the sensor was used to blindly record the joint balance. For this evaluation, the two groups were pooled and categorized as either balanced or unbalanced, as defined by a mediolateral load differential less than 15 lbf (previously described in literature). Clinical outcomes data were collected at 6 weeks, 6 months and 1 year post- operatively, including Knee Society Satisfaction and the Forgotten Joint Score. Using linear mixed models, these outcome measures were compared between the balanced and unbalanced patient groups.Introduction & Aims
Methods
Improper soft-tissue balancing can result in postoperative complications after total knee arthroplasty (TKA) and may lead to early revision. A single-use tibial insert trial with embedded sensor technology (VERASENSE from OrthoSensor Inc., Dania Beach, FL) was designed to provide feedback to the surgeon intraoperatively, with the goal to achieve a “well-balanced” knee throughout the range of motion (Roche et al. 2014). The purpose of this study was to quantify the effects of common soft-tissue releases as they related to sensor measured joint reactions and kinematics. Robotic testing was performed using four fresh-frozen cadaveric knee specimens implanted with appropriately sized instrumented trial implants (geometry based on a currently available TKA system). Sensor outputs included the locations and magnitudes of medial and lateral reaction forces. As a measure of tibiofemoral joint kinematics, medial and lateral reaction locations were resolved to femoral anterior-posterior displacement and internal-external tibial rotation (Fig 1.). Laxity style joint loading included discrete applications of ± 100 N A-P, ± 3 N/m I-E and ± 5 N/m varus-valgus (V-V) loads, each applied at 10, 45, and 90° of flexion. All tests included 20 N of compressive force. Laxity tests were performed before and after a specified series of soft-tissue releases, which included complete transection of the posterior cruciate ligament (PCL), superficial medial collateral ligament (sMCL), and the popliteus ligament (Table 1). Sensor outputs were recorded for each quasi-static test. Statistical results were quantified using regression formulas that related sensor outputs (reaction loads and kinematics) as a function of tissue release across all loading conditions. Significance was set for p-values ≤ 0.05.Introduction
Methods
Patient medical comorbidities are well-established risk modifiers of THA patient outcomes. Patient's mental state preoperatively may influence postoperative functional outcomes though just like any medical comorbidity. This study sought to determine if patient confidence in attaining post-operative functional goals was associated with objective and subjective outcomes following THA. Patients undergoing primary or revision THA at a single institution between 2008 and 2010 were administered a questionnaire consisting of demographics, body mass index, Hip Dysfunction Osteoarthritis and Outcomes Score (HOOS), SF-12 scores, the level of functionality they hoped to gain postoperatively and their confidence in attaining that goal (0–10 scale) preoperatively and postoperatively at last follow-up (minimum 12 months). Measured outcomes included length of stay, 30-day readmission, HOOS, and SF-12 physical component scores. Correlation of patient confidence in attaining treatment goals and the outcomes collected was established using multiple linear and logistic regression models that were adjusted for all variables, including baseline mental and functional scores.Introduction:
Methods:
The prevalence of total hip (THA) and knee arthroplasty (TKA) is growing dramatically, with more than 1 million procedures performed annually in the United States. As the cost of and demand for the newest orthopaedic implants continue to rise, the price paid to medical device companies for implants is a growing concern. Some high-volume healthcare institutions have adopted price capitation strategies to control costs, in which a flat purchase price is negotiated for all implant line items regardless of technology and material. The purpose of this study was to evaluate whether the implementation of price capitation in a large health system affected trends in THA and TKA premium implant selection by surgeons. A secondary objective was to compare selection trends between surgeons with an academic center affiliation and community practice surgeons, within a single health system. All consecutive primary THA and TKA cases six months before (1/1/2011–6/30/2011) and after (8/1/2011–1/31/2012) implementation of a capitated pricing strategy (7/1/2011) were identified. Surgeon education regarding the new pricing policy was conducted for 1-month following implementation, and data during this time were omitted from the study. After exclusions (Figure 1), a total of 481 THA and 674 TKA from the large hospital, and 253 THA and 315 TKA from the two community hospitals comprised the final study cohort. A retrospective review of patient demographics and implant characteristics for each case was performed. Premium THA implants were defined by the existence of one of the following bearing surfaces: second (2G) or third generation (3G) highly cross-linked polyethylene liner with a ceramic or oxidized-zirconium femoral head, ceramic liner with a ceramic femoral head, or mobile-bearing system. Premium TKA implants were defined by the existence of at least one of the following criterion: mobile-bearing design, high-flexion design, oxidized-zirconium femoral component, and/or highly cross-linked polyethylene bearing surface. Pearson's chi-square analyses and Fisher's exact test were used to compare implant usage between pre- and post-capitated pricing time periods.Introduction:
Methods:
Over the last several decades, life expectancy following solid organ transplant (i.e. kidney, liver, heart, lung, and pancreas) has increased significantly, largely due to improvements in surgical technique, immunosuppressive regimens, patient selection, and postoperative care. As this population ages, many of these transplant patients become candidates for total knee arthroplasty (TKA). However, these patients may be at greater risk of complications following TKA due to immunosuppression and metabolic derangements secondary to organ dysfunction. The purpose of this study was to use a large, nationally representative database to compare morbidity, mortality, length of stay (LOS), and charges for TKA patients with and without a history of solid organ transplant. This retrospective study was a review of the Nationwide Inpatient Sample (NIS; the largest all-payer inpatient care United States database representing a 20% stratified sample) from 1998 to 2010. Patients who had a primary TKA (ICD-9-CM 81.54) were included (n = 5,706,675, weighted national frequency). A total of 763,924 cases were excluded for the following: age <18 years, pathologic fracture of lower extremity, malignant neoplasm and/or metastatic cancer, previous and/or bilateral arthroplasty, admission type other than “elective”. The remaining 4,942,751 patients were categorized as transplant (n = 5,245; included only liver, kidney, heart, lung and/or pancreas transplant) or non-transplant group (n = 4,931,017; no history of any transplant including solid organ or tissue). A multivariable regression model was used to identify any association(s) between a history of solid organ transplant and morbidity, mortality, LOS and hospital charges, while adjusting for patient and hospital characteristics.Introduction:
Methods:
Acetabular component malpositioning in total hip arthroplasty increases the risk of dislocations, impingement, and long-term component wear. The purpose of this Sawbones study was to define the efficacy of a novel acetabular imprinting device (AID) with 3D preoperative planning in accurately placing the acetabular component. Four surgeons performed the study on osteoarthritic and dysplastic Sawbone models using 3 different methods for placing the acetabular component (total n = 24). The 3 methods included (1) standard preoperative planning and instrumentation (i.e., standard method), (2) 3D computed tomographic (CT) scan planning and standard instrumentation (i.e., 3D planning method), and (3) 3D CT scan planning combined with an acetabular imprinting device (i.e., AID method). In the AID method, 3D planning software was used to virtually place the acetabular component at 40° of inclination and 22° of anteversion and create a parallel guide pin trajectory. A patient-specific surrogate bone model with a built-in guide pin trajectory was then manufactured as a stereoltihography device (Fig. 1A). The surgeon molded bone cement into the acetabulum imprinting the acetabular features while maintaining the guide pin trajectory (Fig. 1B). Afterward, the AID was removed from the surrogate bone model and placed onto the Sawbone, ensuring a secure fit (Fig. 1C). A guide pin was drilled into the Sawbone along the prescribed trajectory. With the guide pin in place, the surgeon could ream the acetabulum and impact the acetabular component using the guide pin as a visual aid (Fig. 1D). Postoperatively, a CT scan was used to define and compare the actual implant location with the preoperative plan. Statistical analysis was performed as 3 group comparisons using the chi-squared test for categorical data and analysis of variance (ANOVA) for continuous measurements.Background:
Methods:
While indications for total knee (TKA) and hip arthroplasty (THA) have expanded over the last 35 years, implant labeling has largely remained stagnant, with conditions including obesity, developmental dysplasia, and many others (Table 1) still considered as contraindications. Implant labeling has not co-evolved with surgical indications, as most orthopaedic implants are cleared through the 510(k) process, which conserves the labeling of the predicate device. While surgeons can legally use devices for off-label indications, the scrutiny regarding off-label use of orthopaedic implants has intensified. The objective of this study was to determine the incidence of off-label use at our institution, define the risk in terms of revision rate associated with off-label use, and to compare activity level, functional outcomes, and general health outcomes for on- and off-label TKA and THA patients. Patients who underwent primary TKA or THA at a large academic tertiary referral center between January 1, 2010 and June 30, 2010 were considered for the study (n = 705). Of this cohort, a convenience sample of 283 patients were selected for the study based on the presence of baseline outcomes data. Patients were contacted via mail and/or phone to collect details regarding potential revision surgeries, UCLA activity scores, short form-12 (SF-12), Knee Injury and Osteoarthritis Outcome Score (KOOS) or Hip Disability and Osteoarthritis Outcome Score (HOOS). Using labeled contraindications from the product inserts from multiple orthopaedic implant manufacturers, procedures were categorized as on-label or off-label. Outcomes including revision rate, activity score, and SF-12, KOOS, and HOOS scores were adjusted for age, gender, and BMI by fitting a logistic model and analyzed using the Wald chi-square test (SPSS, Chicago, IL).Introduction:
Methods:
Experimental testing reproducing activity specific joint-level loading has the potential to quantify structure-function relationships, evaluate intervention possibilities, perform device analysis, and quantify joint kinematics. Many recent technological advancements have been made in this field and inspire this study's aim to present a framework for the application of activity dependent tibiofemoral loading in a specific custom developed 6 degree of freedom (DOF) robotic test frame. This study demonstrates a pipeline wherein kinetic and kinematic data from subjects were collected in a gait lab, analyzed through musculoskeletal modeling techniques, and applied to cadaveric specimens in the robotic testing system in a real-time manner. This pipeline (Figure 1 blue dotted region) fits into a framework for synergistic development and refinement of arthroplasty techniques and devices. Gait lab kinetic and kinematic data for walking was collected from 5 subjects. Subject-specific musculoskeletal modeling was performed to determine 6 DOF active component joint loading (OpenSim version 2.4, Introduction
Methods
Solid organ transplant patients are living longer than in past decades, largely due to improvements in surgical technique, immunosuppressive regimens, patient selection, and postoperative care. As these patients grow older, many of them present for total hip arthroplasty (THA). However, life-long immunosuppressive therapy, metabolic disorders, and post-transplant medications may place transplant patients at higher risk for complications following THA. The objective of this study was to use a national administrative database to compare morbidity, acute complications, in-hospital mortality, length of stay (LOS), and admission costs for THA patients with and without solid organ transplant history. The Nationwide Inpatient Sample (NIS), the largest all-payer inpatient care database representing a 20% stratified sample of United States hospitals, was retrospectively queried for primary THA (ICD-9-CM 81.51) patients from 1998 to 2009 (n = 2,567,930; weighted national frequency). Cases were excluded (n = 324,837) for the following: age <18 years, pathologic fracture of lower extremity, malignant neoplasm and/or metastatic cancer, primary diagnosis of femoral neck fracture, admission type other than “elective,” previous and/or bilateral arthroplasty. The remaining 2,243,093 THA patients were assigned to transplant (n = 6,319; liver, kidney, heart, lung and/or pancreas transplant history) or non-transplant groups (n = 2,231,446; no history of any transplant including solid organ or tissue). Acute complications included a variety of organ-specific and procedure-related complications (i.e. mechanical implant failure, dislocation, hematoma, infection, pulmonary embolism, venous thrombosis). Multivariable regression and general estimating equations were developed to study the effect of transplant history on outcomes, adjusting for patient/hospital characteristics and comorbidity.Introduction:
Methods:
Primary total knee arthroplasty (TKA) is associated with perioperative bleeding, and some patients will require allogenic blood transfusion during their inpatient admission. While blood safety has improved in the last several decades, blood transfusion still carries significant complications and costs. Transfusion indications and alternative methods of blood conservation are being explored. However, there is limited nationally representative data on allogenic blood product utilization among TKA patients, and its associated outcomes and financial burden. The purpose of this study was to use a national administrative database to investigate the trends in utilization and outcomes (i.e. in-hospital mortality, length of stay, admission costs, acute complications) of allogenic blood transfusion in primary TKA patients. The Nationwide Inpatient Sample (NIS), the largest all-payer inpatient care database representing a 20% stratified sample of United States hospitals, was utilized. Primary TKA (ICD-9-CM 81.54) cases from 2000 to 2009 were retrospectively queried (n = 4,544,999; weighted national frequency). A total of 67,841 admissions were excluded (Figure 1). The remaining 4,477,158 cases were separated into two study cohorts: (1) patients transfused with allogenic blood products (red blood cells, platelets, serum) (n = 540,270) and (2) patients not transfused (n = 3,936,888). Multivariable regression and generalized estimating equations were used to examine the effect of transfusion on outcomes, adjusting for patient/hospital characteristics and comorbidity.Introduction:
Methods:
The acetabular labrum is an essential stabilizer of the hip joint, imparting its greatest effect in extreme joint positions where the femoral head is disposed to subluxation and dislocation. However, its stabilizing value has proved difficult to quantify. The objective of the present study was to assess the contribution of the entire acetabular labrum to mechanical joint stability. We introduce a novel “dislocation potential test” that utilizes a dynamic, cadaveric, robotic model that functions in real-time under load-control parameters to map the joint space for low-displacement determination of stability, and quantify using the “stability index”. Five fresh-frozen human cadaveric hips without labral tears were mounted to a six-degree-of-freedom robotic manipulator and studied in 2 distinct joint positions provocative for either anterior or posterior dislocation. Dislocation potential tests were run in 15° intervals, or sweep planes, about the face of the acetabulum. For each interval, a 100 N force vector was applied medially and swept laterally until dislocation occurred. Three-dimensional kinematic data from conditions with and without labrum were quantified using the stability index, which is the percentage of all directions a constant force can be applied within a given sweep plane while maintaining a stable joint.Background
Methods
Two-stage revision is considered the gold standard for treatment of knee prosthetic joint infections. Current guidelines for selecting the most appropriate procedure to eradicate knee prosthetic joint infections are based upon the duration of symptoms, the condition of the implant and soft tissue evaluated during surgery and the infecting organism. A more robust tool to identify candidates for two-stage revision and who are at high risk for treatment failure might improve preoperative risk assessment and increase a surgeon's index of suspicion, resulting in closer monitoring, optimization of risk factors for failure and more aggressive management of those patients who are predicted to fail. Charts from 3,809 revision total joint arthroplasties were reviewed. Demographic data, clinical data and disease follow-up on 314 patients with infected total knee arthroplasty treated with two-stage revision were collected. Univariate analyses were performed to determine which variables were independently associated with failure of the procedure to eradicate the prosthetic joint infections. Cox regression was used to construct a model predicting the probability of treatment failure and the results were used to generate a nomogram which was internally validated using bootstrapping.Background
Methods
Pain, swelling and inflammation are expected
during the recovery from total knee arthroplasty (TKA) surgery.
The severity of these factors and how a patient copes with them
may determine the ultimate outcome of a TKA. Cryotherapy and compression
are frequently used modalities to mitigate these commonly experienced
sequelae. However, their effect on range of motion, functional testing,
and narcotic consumption has not been well-studied. A prospective, multi-center, randomised trial was conducted to
evaluate the effect of a cryopneumatic device on post-operative
TKA recovery. Patients were randomised to treatment with a cryopneumatic
device or ice with static compression. A total of 280 patients were
enrolled at 11 international sites. Both treatments were initiated
within three hours post-operation and used at least four times per
day for two weeks. The cryopneumatic device was titrated for cooling
and pressure by the patient to their comfort level. Patients were evaluated by physical therapists blinded to the
treatment arm. Range of motion (ROM), knee girth, six minute walk
test (6MWT) and timed up and go test (TUG) were measured pre-operatively,
two- and six-weeks post-operatively. A visual analog pain score
and narcotic consumption was also measured post-operatively. At two weeks post-operatively, both the treatment and control
groups had diminished ROM and function compared to pre-operatively.
Both groups had increased knee girth compared to pre- operatively.
There was no significant difference in ROM, 6MWT, TUG, or knee girth
between the 2 groups. We did find a significantly lower amount of
narcotic consumption (509 mg morphine equivalents) in the treatment
group compared with the control group (680 mg morphine equivalents)
at up to two weeks postop, when the cryopneumatic device was being
used (p <
0.05). Between two and six weeks, there was no difference
in the total amount of narcotics consumed between the two groups.
At six weeks, there was a trend toward a greater distance walked
in the 6MWT in the treatment group (29.4 meters A cryopneumatic device used after TKA appeared to decrease the
need for narcotic medication from hospital discharge to 2 weeks
post-operatively. There was also a trend toward a greater distance
walked in the 6MWT. Patient satisfaction with the cryopneumatic
cooling regimen was significantly higher than with the control treatment.
