This study evaluates the impact of radii-related differences in posterior cruciate ligament retaining (PCR) primary total knee arthroplasty (TKA) prosthetic designs on knee biomechanics during level walking 1-year after surgery. The multi-radius (MR) design creates at least two instantaneous flexion axes by changing the radius of curvature of the femoral component throughout the arc of knee motion. The femoral component of the single-radius (SR) design has only one radius and therefore a fixed axis. Subjects scheduled for computer-navigated TKA (n = 37: SR n = 20 [9M, 11F], MR n = 17 [8M, 9F]; 69.8 ± 7.1 years, 87.6 ± 20.8 kg, 1.68 ± 0.09 m), and demographic-matched controls without knee pathology n = 23 [13M, 10F], provided informed consent under the Banner IRB (Sun Health panel). All surgical subjects received similar pre-, peri-, and post-operative care under the direction of three surgeons from a single orthopedic practice. Position and force data were collected using 28 reflective markers (modified Helen Hayes [Kadaba et al 1990]) tracked by ten digital IR cameras (120 Hz) (Motion Analysis Corp., Santa Rosa, CA) and four force platforms (1200 Hz) (AMTI, Watertown, MA) embedded in an 8m walkway. Data were recorded and smoothed (Butterworth filter, 6 Hz) using EVaRT 5.0.4 software (Motion Analysis Corp.). Gait cycle parameters were calculated using the ‘Functional Hip Center’ and ‘Original Knee Axis’ models in Orthotrak 6.6.1 (Motion Analysis Corp.). Data from each group were height and weight normalized and ensemble averaged by affected limb (right limb for controls) using custom code written in Labview (National Instruments Corp, Austin, TX). Descriptive statistics for the maximum and minimum knee kinematic, kinetic, and temporal spatial values in the stance and swing phases of the gait cycle were generated for each group. Between-group comparisons were made using an ANOVA with post hoc testing as appropriate (SPSS 14.0 (SPSS Inc, Chicago, IL)).Introduction:
Methods:
Minimally invasive, computer navigated techniques are gaining popularity for total knee replacement (TKA). While these techniques may have the potential to provide improved functional outcomes with more rapid recovery, little quantitative data exists comparing long-term gait function following surgery with different exposure approaches. This study compares functional gait differences between surgical approach groups two year following TKA. Kinetics, kinematics, and temporospatial parameters were assessed to determine if differences exist between groups in long term follow-up. This study was approved by the Banner IRB (Sun Health Panel). 95 subjects volunteered to participate in the study and signed informed consent prior to testing. The subjects were prospectively randomized to one of four surgical approach groups, mini-midvastus (MV), mini-subvastus (SV), mini-parapatellar (MP), and standard parapatellar (SP). These subjects were also compared to 45 age-matched, asymptomatic controls. Surgery was performed by one of two fellowship trained orthopedic surgeons specializing in adult reconstruction. Subjects were assessed in the gait laboratory two years after receiving surgery. Three dimensional kinetic and kinematic data were captured using a ten-camera passive marker system, a modified Helen Hayes marker set (Eagle-4, Motion Analysis, Santa Rosa, CA), and four floor embedded force platforms (AMTI Inc., Watertown, MA). Subjects were instructed to walk at a self selected speed down an 8 meter walkway. Kinetic and kinematic data were post processed using EVaRT and OrthoTrak 6.23 biomechanical software (Motion Analysis, Santa Rosa, CA). Statistical analyses were performed using SPSS (v14.0, SPSS Inc, Chicago, IL) and included a one-way ANOVA and post hoc testing.Introduction
Methods
The current standard of care for postoperative support during ambulation is a walker and accompanying gait belt. The use of a walker necessitates awkward body positioning, adequate upper body strength, and prohibits natural foot over foot progression during gait. Additionally, use of a gait belt necessitates that the therapist remains immediately beside or behind the patient, limiting the view of the patient's gait pattern and placing the therapist and patient at risk should the patient fall. The Secure Tracks™ (Fig 1) is a patient support device which runs in an overhead track and supports the patient in the periaxillary region, providing a more natural body position and foot progression while limiting the risk of falls. This prospective randomized study compares the rate of ambulation and other clinical outcomes measures in a population of total knee replacement recipients postoperatively. A total of 31 unilateral total knee recipients were enrolled in this prospective randomized comparison between the standard of care gait training and the Secure Tracks device. IRB approval was obtained from the relevant oversight board. Patients were permitted to weight-bear as tolerated starting the evening of their surgical procedure. Patients were instructed to walk until they felt fatigued or unsafe and were not encouraged or discouraged to stop. The therapists tracked the distance each patient walked during each of their ambulation sessions and also recorded any incidence of falls or other adverse events. A timed up and go test (TUG) and Visual Analogue Scale for pain (VAS) were also administered at the time of consent, at discharge from the hospital, and at the 2 week clinic followup appointment.Introduction
Methods
When using press-fit stems in revision total knee arthroplasty (TKA), diaphyseal engagement optimizes stability. Attempts to maximize press fit may lead to periprosthetic fracture; however, the literature offers no guidance regarding the prevalence or management of this complication. The purpose of this study is to report the incidence, risk factors, and outcomes of these fractures. 634 Stemmed implants (307 femoral and 327 tibial) from 413 consecutive revision TKAs were reviewed. Immediate and 6 week post-operative radiographs were examined. Patient age, gender, stem length, diameter, and offset were evaluated as potential risk factors for fracture occurrence using a paired t-test for continuous and a chi-square analysis for categorical variables.Introduction
Methods
