The epidemiology of re-revision total hip arthroplasty (THA) is not well understood. The purpose of this study is to investigate the epidemiology of re-revision THA, and identify risk factors that are associated with failure of re-revision THA. A retrospective analysis was performed on 288 patients who underwent revision THA at a single institution between 1/2012 and 12/2013. Patients who underwent revision hip arthroplasty two or more times were included. Patients were excluded if their indication for their first revision was due to periprosthetic joint infection (PJI). Patient demographics, surgical indications, revision details, and available follow-up information were collected through the electronic medical record. Re-revision failure was defined as the need for any additional return to the operating room, regardless of indication. A logistic regression analysis was performed to assess for significant predictors of re-revision failure.Introduction
Methods
Total knee arthroplasty (TKA) surgical techniques attempt to achieve equal flexion and extension gaps to produce a well-balanced knee. Anterior knee pain, which is not addressed by flexion-extension balancing, is one of the more common complaints for TKA patients. The variation in patellofemoral balance resulting from the techniques to achieve equal flexion and extension gaps has not been widely studied. The purpose of the study is to determine the effects on cruciate retaining (CR) TKA patellofemoral balance when equal flexion and extension gaps are maintained while changing femur implant size and/or adjusting the femur and tibia implant proximal -distal and femur anterior-posterior positions.Background
Purpose of study
Spinal deformity has a known deleterious effect upon the outcomes of total hip arthroplasty and acetabular component positioning. This study sought to evaluate the relationship between severity of spinal deformity parameters and acetabular cup position, rate of dislocation, and rate of revision among patients with total hip arthroplasties and concomitant spinal deformity. A prospectively collected database of patients with spinal deformity was reviewed and patients with total hip arthroplasty were identified. The full body standing stereoradiographic images (EOS) were reviewed for each patient. From these images, spinal deformity parameters and acetabular cup anteversion and inclination were measured. A chart review was performed on all patients to determine dislocation and revision arthroplasty events. Statistical analysis was performed to determine correlation of deformity with acetabular cup position. Subgroup analysis was performed for patients with spinal fusion, dislocation events, and revision THA.Background
Methods
Achieving proper ligament tension in knee flexion within cruciate retaining (CR) total knee arthroplasty (TKA) has long been associated with clinical success. The distal femoral joint line (DFJL) is routinely used as a variable to assist in achieving proper flexion-extension gap balancing. No prior study has observed the possible effects of properly restoring the DFJL may have on ligament tension in flexion. The purpose of this computational analysis was to determine what effect the DFJL may have on ligament strains and tibiofemoral kinematics of CR knee designs in flexion. A computational analysis was performed utilizing a musculoskeletal modeling system with ligaments modeled as non-linear elastic. Tibiofemoral kinematics, contact points estimated from the femoral condyle low points, and ligament strain, change in length relative to the unloaded length, were measured at 90° knee flexion during a deep knee bend activity. Two different knee implants, a High Flexion CR (HFCR) and a Guided Motion CR (GMCR) design were used. Simulations were completed for changes in superior-inferior (SI) positioning of the femoral implant relative to the femur bone, in 2mm increments to simulate over and under resection of the DFJL.Introduction
Methods
Achieving proper ligament tension in knee flexion within posterior cruciate retaining (CR) total knee arthroplasty (TKA) has long been associated with clinical success. Ligament balance has been achieved through specific surgical technique steps. No prior study evaluated the possible effects of varying levels of posterior cruciate ligament (PCL) release on femorotibial contact location and PCL ligament strain. The purpose of this computational analysis was to determine what effect-varying levels of PCL release may have on the tibiofemoral kinematics and PCL strain. A computational analysis was performed utilizing a musculoskeletal modeling system with ligaments modeled as non-linear elastic structures and ligament insertions. A single CR knee system with two different tibial insert designs was tested, a Guided Motion (GM) and an ultra-congruent, Deep Dished (DD) design. Varying levels of PCL release were simulated by setting the stiffness of both bundles of the PCL to a percentage, ranging from 0–100% in 25% increments. Tibiofemoral kinematics was evaluated by measuring the contact points estimated from the femoral condyle low points, and ligament strain of the anterior-lateral (AL) and posterior-medial (PM) bundles. The maximum PCL strain was determined for each bundle to evaluate the risk of PCL rupture based on the PCL failure strain.Introduction
Methods
Total knee arthroplasty (TKA) is a very successful procedure with good clinical outcomes. However, the effects of obesity on TKA outcomes remain controversial and inconclusive. The objective of this study was to quantify the biomechanical effects of simulated obesity on Cruciate Retaining (CR) and Posterior Stabilized (PS) TKA in human cadaveric knees. We hypothesized that biomechanical characteristics of CR TKA will be less dependent on simulated obesity compared to PS TKA. Eight cadaveric knees (4 male, 4 female) average age 68.4 years (range, 40–86 years) underwent TKA and were tested using a custom knee testing system. Specifically, Cruciate Retaining (CR) and Posterior Stabilized (PS) Lospa Knee System (Corentec Inc.) were implanted and tested sequentially using internal control experimental design. The muscle loading was determined based on the physiological cross-sectional area ratio of the quadriceps and hamstring muscles. The ratios were then applied to CDC data representing the average male height and used to simulate a BMI of 25, 30, and 35 at knee flexion angles (KFA) of 15, 30, 45, 60, 75, and 90 degrees. Patellofemoral and tibiofemoral joint contact areas and pressures were measured using the K-scan sensor system (Tekscan Inc, South Boston, MA). Contact area, force, pressure and peak contact pressure were obtained and analyzed for each specimen. Knee kinematics were quantified using a Microscribe 3DLX digitizer (Revware Inc, Raleigh, North Carolina). Repeated measure analysis of variance with a Tukey post hoc test was used to compare loading conditions. Comparisons between the CR and PS TKA groups were made with a paired INTRODUCTION
METHODS
The analysis of hip joint vibrations (phonoarthrography, vibration arthrometry, vibroarthrography, hip auscultation) has been explored as a means to assess joint pathologies, disease status and recently, incipient prosthesis failure. Frequencies <
100Hz have been used to diagnose gross pathology and wear in knee prostheses, frequencies from 1k to 10k Hz for progression of osteoarthritis, and frequencies >
10k Hz for loosening of cemented hip prostheses. It is possible that detailed analysis of higher frequencies could detect and quantify the smaller geometric changes (asperities) that develop in articular prosthetic wear. We examined the ultrasound emission generated by various types of hip prostheses and native hips of 98 patients. The ultrasonic transducer was attached to the skin over the greater trochanter with a hypoallergenic, transparent dressing using a standard acoustic coupling gel layer on the microphone face to improve skin contact. The transducer was attached by a 2m cord to a battery operated, data recorder/logger. The patients were asked to sit in a chair, rise, sit again and then rise and take 5 steps while recording the acoustic data from these two movements of sitting and walking. This procedure was repeated for the opposite hip in each patient as well. Acoustic emission analysis examined frequency distributions and power spectrums of the recorded signals and their relations to prosthesis type and implantation time. Review of x-rays of prosthetic and native hips was carried out with OA grading and prosthetic wear quantification. We have obtained data on 79 metal-polyethylene (average duration of 8.5 years; 0.1–28), 20 ceramic-ceramic (average duration of 8.5 years; 0.5–10), 17 metal-metal (average duration of 1.2 years; 0.1–5.5) and 15 ceramic-polyethylene (average duration of 0.6 years; 0.1–1) hip arthroplasties as well as 75 native hips. Analysis of the data enabled us to tell the difference between patients whose native hips did not cause them any discomfort and those patients with painful osteoarthritis (initial findings indicate that OA severity can be quantified as well). The measurements of wear of the metal-polyethylene prostheses obtained from patients’ x-rays were compared to an analysis of the ultrasonic emissions, a homogeneity showed no significant differences (all p’s >
0.24) between the curve type and amount of wear of the prosthesis polyethylene. Our data suggests that we are capable of assessing the status of OA by acoustic emission. Further analysis of wear data coupled to ultrasonic emission is needed for accurate quantification of THA wear.
