Nao Shibanuma

Limb positioning is critical for defining patellofemoral alignment and femoral shape

The source of patellofemoral pain is a common orthopaedic complaint that often is difficult to determine because of the lack of correlation between symptoms and specific clinical measurements. Excessive joint contact stresses resulting from patellofemoral malalignment and pathologic femoral shape often are associated with this pain. These measures are likely sensitive to the limb position (orientation and position relative to the imaging system with which they are quantified). Because of this sensitivity, the measures have large variations and do not show correlations with subjective symptoms. The purpose of this study was to determine if varying limb position resulted in significant changes in standard clinical measures of patellofemoral alignment and femoral shape. This dependence was investigated by simulating alterations in limb position through resectioning of three-dimensional magnetic resonance image sets (20 healthy knees) to create axial images with altered orientation (eight images) or location (four images) relative to a fixed reference. By quantifying the variability of the clinical measures across all images, it was determined that simulated alterations in limb position produced greater variability in femoral shape and patellofemoral alignment measures than the variability seen across control subjects. This indicated that a standardized method for establishing limb position relative to the imager is warranted.

Novel Image-matching Software for Postoperative Evaluation After TKA

Although 2-dimensional assessments using postoperative plain radiographs have been used after total knee arthroplasty (TKA) in previous studies, a strong possibility exists that deviation can occur when assessing 3-dimensional (3-D) objects. The purpose of this study was to test the hypothesis that novel 3-D image-matching software could accurately assess the positioning of implants and could be a useful tool in postoperative evaluation after TKA.Total knee arthroplasty was performed in 30 consecutive patients. Intraoperatively, the thickness of each bone cut was measured. Postoperatively, the thickness of each part of the bone cut was measured using Athena Knee (SoftCube Co, Ltd, Osaka, Japan) 3-D image-matching software. The results revealed no significant differences in the medial compartment and significant differences of approximately 1 mm in the lateral compartment. The difference was possibly caused by the remaining cartilage in the lateral compartment. Linear regression analysis revealed a statistically excellent correlation between intra- and postoperative values in all parts of the bone cuts. Although the 3-D image-matching software used in this study was originally developed for preoperative planning in TKA, it is considered accurate enough to assess the positioning of implants with respect to the bone after TKA.

Leg Edema Due to a Mass in the Pelvis After a Large-Diameter Metal-On-Metal Total Hip Arthroplasty

We report the case of a patient with leg edema after large-diameter metal-on-metal total hip arthroplasty. At 1 year and 2 months after primary left large-diameter metal-on-metal total hip arthroplasty, the patient complained of left leg edema. At first, we suspected deep venous thrombosis. However, deep venous thrombosis was not detected by venous ultrasonographic examination. Computed tomography imaging revealed a mass in front of the iliac fossa. The mass compressed the left iliac artery and vein. We therefore believed that this lesion was the cause of the leg edema and performed resection of the mass. The resected mass consisted of necrotic tissue infiltrating inflammation cells, so it was diagnosed as pseudotumor. Unilateral leg edema disappeared gradually after the resection.

Sensitivity of femoral orientation estimates to condylar surface and MR image plane location

To define the femoral anatomic region that provides the most reliable reference for measuring femoral orientation, from which patellofemoral and tibiofemoral orientation can be measured.

Ultrasonography System Aided by Fuzzy Logic for Identifying Implant Position in Bone

We describe a new ultrasonography system, which can identify an implant position in bone. Although conventional X-ray fluoroscopy can visualize implants, it has the serious disadvantage of X-ray exposure. Therefore, we developed a system for orthopedic surgery that involves no X-ray exposure. Barriers to the development of the system were overcome using an ultrasonic instrument and fuzzy logic techniques. We located distal transverse screw holes in an intramedullary nail during surgery for femur fracture. The screw hole positions are identified by calculating two fuzzy degrees of intensity and the variance. Results allow this system to identify the screw hole positions within an error of 1.43 mm, an error ratio adequate for clinical surgical practice.

Analysis of weight-bearing kinematics of posterior-stabilized total knee arthroplasty with novel helical post-cam design.

We developed a new posterior-stabilized total knee arthroplasty (TKA) with a unique post-cam design that induces and accommodates internal tibial rotation with deep knee flexion. To validate the design concept of this system, we conducted an image analysis study employing a computer-aided diagnosis system for 24 TKA-implanted knees. In the analysis, the tibiofemoral relationship in the following 3 postures was evaluated: standing at extension, forward lunge, and kneeling with maximum knee flexion. The results of the image analysis showed achievement of consistent internal rotation of the tibia in deep flexion with a broad contact area at the post-cam interface as intended by the original design concept of this TKA system.

The influence of intraoperative soft tissue balance on patellar pressure in posterior-stabilized total knee arthroplasty

BACKGROUND Appropriate soft tissue balance is essential for the success of total knee arthroplasty (TKA), and assessment with an offset-type tensor provides useful information about the femorotibial (FT) joint. The purpose of the study was to investigate the relationship between intraoperative soft tissue balance and patellar pressure at both medial and lateral sides. METHODS Thirty varus-type osteoarthritis patients who received mobile-bearing posterior-stabilized TKAs were enrolled in the study. Using the tensor, soft tissue balance, including joint component gap and varus ligament balance, was recorded at 0°, 10°, 30°, 60°, 90°, 120°, and 135° with patellofemoral (PF) joint reduction and femoral component placement. Following final prostheses implanted with appropriate insert, the medial and lateral patellar pressures were measured at each flexion angle. A simple regression analysis was performed between each patellar pressure, parameter of soft tissue balance, and postoperative flexion angle. RESULTS Both lateral and medial patellar pressures increased with flexion. The lateral patellar pressure was significantly higher than the medial patellar pressure at 60°, 90°, and 135° of flexion (p<0.05). The lateral patellar pressure inversely correlated with the varus ligament balance at 60° and 90° of flexion (p<0.05). The lateral patellar pressure at 120° and 135° of flexion inversely correlated with the postoperative flexion angle (p<0.05). CONCLUSION Soft tissue balance influenced patellar pressure. In particular, a reduced lateral patellar pressure was found at the lateral laxity at flexion, leading to high postoperative flexion angle. LEVEL OF EVIDENCE III.

Use of Image-Free Navigation in Determination of Acetabular Cup Orientation: Analysis of Factors Affecting Precision

We have been using an image-free total hip arthroplasty (THA) navigation system (OrthoPilot; Aesculap, Tuttlingen, Germany) to ensure accurate and reproducible acetabular cup orientation. In this study, the accuracy of this system in the assessment of acetabular cup orientation was evaluated by comparing the intraoperative inclination and anteversion angles presented by the navigation system and the corresponding postoperative values obtained by computed tomography measurement. In the intraoperative accuracy analysis, we additionally examined the influence of factors such as body mass index and soft tissue thickness on assessment error. Intraoperative and postoperative results obtained from 115 consecutive navigated THAs were compared and analyzed. In both inclination and anteversion angles, good agreement was observed; a discrepancy of more than 5° was observed in 1 and 3 cases, respectively. In the analysis of factors potentially affecting the accuracy of the intraoperative assessment, no correlation between each parameter and the intraoperative and postoperative discrepancy was demonstrated.

Robust Pelvic Coordinate System Determination for Pose Changes in Multidetector-row Computed Tomography Images

For developing navigation system of total hip arthroplasty (THA) and evaluating hip joint kinematics, 3-D pose position of the femur and acetabulum in the pelvic coordinate system has been quantified. The pelvic coordinate system is determined by manually indicating pelvic landmarks in multidetector-row computed tomography (MDCT) images. It includes intra- and inter-observer variability, and may result in a variability of THA operation or diagnosis. To reduce the variability of pelvic coordinate system determination, this paper proposes an automated method in MDCT images. The proposed method determines pelvic coordinate system automatically by detecting pelvic landmarks on anterior pelvic plane (APP) from MDCT images. The method calibrates pelvic pose by using silhouette images to suppress the affect of pelvic pose change. As a result of comparing with manual determination, the proposed method determined the coordinate system with a mean displacement of 2.6 ± 1.6 mm and a mean angle error of 0.78 ± 0.34 deg on 5 THA subjects. For changes of pelvic pose position within 10 deg, standard deviation of displacement was 3.7 mm, and of pose was 1.28 deg. We confirmed the proposed method was robust for pelvic pose changes.

Periarticular multimodal drug injection improves post-operative pain and functional recovery after total knee arthroplasty

BACKGROUND This study retrospectively compared the clinical benefits of periarticular multimodal drug injection (PMDI) and continuous femoral nerve block (CFNB) after total knee arthroplasty (TKA). METHODS From 2010 to 2012, 520 primary TKAs were performed, and patients were treated with CFNB or PMDI after surgery. Patients who underwent simultaneous bilateral TKA were excluded, leaving 185 and 166 patients in the CFNB and PMDI groups, respectively. Numeric rating scale for pain (NRS) scores and analgesic consumption were evaluated to compare the effectiveness of pain control between the groups. Further, range of motion (ROM), extension lag, the time to recovery of functions, and postoperative C-reactive protein (CRP) levels were monitored. Complications such as deep infection were assessed. RESULTS The PMDI group displayed a significantly smaller NRS score on postoperative day (POD) 1 and lower analgesic consumption on PODs 0 and 1. The times to functional recovery were significantly shorter and the extension lag was smaller in the PMDI group. Furthermore, CRP levels were lower in the PMDI group by POD 7. No obvious deep infections were noted. CONCLUSION Our results indicate that PMDI induced earlier functional recovery after TKA than CFNB, partially via its analgesic effect.