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
An equal knee joint height during flexion and extension is of critical importance in optimizing soft-tissue balancing following total knee arthroplasty (TKA). However, there is a paucity of data regarding the in-vivo knee joint height behavior. This study evaluated in-vivo heights and anterior-posterior (AP) translations of the medial and lateral femoral condyles before and after a cruciate-retaining (CR)-TKA using two flexion axes: surgical transepicondylar axis (sTEA) and geometric center axis (GCA). Eleven patient with advanced medial knee osteoarthritis (age: 51–73 years) who scheduled for a CR TKA and 9 knees from 8 healthy subjects (age: 23–49 years) were recruited. 3D models of the tibia and femur were created from their MR images. Dual fluoroscopic images of each knee were acquired during a weight-bearing single leg lunge. The OA knee was imaged again one year after surgery using the fluoroscopy during the same weight-bearing single leg lunge. The in vivo positions of the knee along the flexion path were determined using a 2D/3D matching technique. The GCA and sTEA were determined based on existing methods. Besides the anterior-posterior translation, the femoral condyle heights were determined using the distances from the medial and lateral epicondyle centers on the sTEA and GCA to the tibial plateau surface in coronal plane (Fig. 1). The paired t-test was applied to compare the medial and lateral condyle motion within each group (Healthy, OA, and CR-TKA). Two-way ANOVA followed post hoc Newman–Keuls test was adopted to detect significant differences among the groups. p<0.05 was considered significant.Introduction
Methods
Locking plates can provide greater stability than conventional plates; however, reports revealed that fractures had a high incidence of failure without medial column support; the mechanical support of medial column could play a significant role in humeral fractures. Recent studies have demonstrated the importance of intramedullary strut in proximal humeral fracture fixation, the relationship to mechanical stability and supporting position of the strut remain unclear. The purpose of this study was to evaluate the influence of position of the intramedullary strut on the stability of proximal humeral fractures using a locking plate. Ten humeral sawbone (Synbone) and locked plates (Synthes, cloverleaf plate), with and without augmented intramedullary strut (five in each group) for proximal humerus fractures, were tested using material testing machine to validate the finite element model. A 10 mm osteotomy was performed at surgical neck and a strut graft (10 cm in length) was inserted into the fracture region to lift the head superiorly. Each specimen was statically tested at a rate of 5 mm/min until failure. To build the finite element (FE) model, 64-slices CT images were converted to create a 3D solid model. The material properties of screws and plates were modeled as isotropic and linear elastic, with an elastic modulus of 110 GPa, (Poisson's ratio, n=0.3). The Young's moduli of cortical and cancellous bones were 17 GPa and 500 MPa (n=0.4), respectively. Three alter shifting toward far cortex by 1, 2, and 3 mm in humeral canal were installed in the simulating model.Introduction
Materials and methods
Distal femur fracture is a critical issue in orthopedic trauma, because it is difficult to manage especially in cases with intra-articular fracture. Osteoporosis may cause instability of implant and increase complications. Few studies investigate on the stability of distal femur osteoporotic fracture and the behaviors under cycling. Our hypothesis was that the stiffness of construct would decrease as cycling in osteoporotic bone. Seven cadaver specimens were used in this study. Relative bone density for each specimen was evaluated using CT scanning by three known calibration phantoms scanned simultaneously with the specimen. All cadaver specimens were divided normal (group 1) and osteoporosis (group 2) in accordance with the bone density. The titanium distal femur locking plates with 6 screws placed in distal femur condyle and 4 in shaft. A 10 mm gap with 65 mm proximal to the center of articular surface and a vertical fractural line between intra-articular were created to simulate AO C2 type fracture. Each specimen was cyclically loaded in two-phase at a frequency of 2 Hz. Phase 1 was set at 1000 N for 10000 cycles. In phase 2, the load was set at 2000 N for 10000 cycles. Then, the specimen was loaded up to failure at a rate of 5 mm/min. Stiffness was evaluated from the linear portion of load-displacement curve at 2000 cycle interval.Introduction
Materials and Methods
Combined acetabular and femoral anteversion (CA) of the hip following total hip arthroplasty (THA) is critical to the hip function and longevity of the components. However, no study has been reported on the accuracy in restoration of CA of the hip after operation using robotic assistance and conventional free-hand techniques. The purpose of this study was to evaluate if using robotic assistance in THA can better restore native CA than a free-hand technique. Twenty three unilateral THA patients participated in this study. Twelve of them underwent a robotic-arm assisted THA (RIO® Robotic Arm Interactive Orthopedic System, Stryker Mako., Fort Lauderdale, FL, USA) and eleven received a free-hand THA. Subject specific 3D models of both implanted and non-implanted hips were reconstructed using post-operative CT scans. The anteversion and inclination of the native acetabulum and implanted cup were measured and compared. To determine the differences of the femoral anteversion between sides, the non-implanted native femur was mirrored and aligned with the remaining femur of the implanted side using an iterative closest point algorithm. The angle between the native femoral neck axis and the prosthesis neck axis in transverse plane was measured as the change in femoral anteversion following THA. The sum of the changes of the acetabular and femoral anteversion was defined as the change of CA after THA. A Wilcoxon signed rank test was performed to test if the anteversion of the navigation and free-hand THAs were different from the contralateral native hips (α = 0.05). The acetabular anteversion were 22.0°±7.4°, 35.9°±6.5° and 32.6°±22.6° for the native hips, robotic assisted THAs and free-hand THAs, respectively, and the corresponding values of the acetabular inclinations were 52.0°±2.9°, 35.4°±4.4° and 43.1°±7.1°. The acetabular anteversion was increased by 12.2°±11.1° (p=0.005) and 12.5°±20.0° (p=0.102) for the robotic assisted and the free-hand THAs. The femoral anteversion was increased by 6.3°±10.5° (p=0.077) and 11.0°±13.4° (p=0.014) for the robotic assisted and free-hand THAs, respectively. The CA were significantly increased by 18.5°±11.7° (p<0.001) and 23.5°±26.5° (p=0.019) for the robotic assisted and the free-hand THAs. The changes of the CA of the free-hand THAs varied in a larger range than those of the robotic assisted THAs. This study is the first to evaluate the changes in acetabular and femoral anteversions of the hips after robotic assisted and free-hand THAs using the contralateral native hip as a control. The results demonstrate that both the navigation and free-hand THAs significantly increased the CA compared to the contralateral native hips, but the changes of the robotic assisted THAs (18.5°±11.7°) were smaller and varied less than those of the free-hand THAs (23.5°±26.5°). These data suggest that the robotic assisted THA can better restore the native hip CAs with higher repeatability than the free-hand technique. Further studies are needed to investigate the effects of the hip anteversion changes on the
Hip arthroplasty is very successful in order to alleviate pain and improve health-related quality of life. Health-care costs are constantly growing and the burden of patients with hip disease has increased dramatically. Careful consideration of the patients'need and expectations include not only the proper indication for surgery but also choice of method. Hip resurfacing (HRA) has been popularized during the last decade, being bone conservative, capable to restore the anatomical hip center and lower the risk of dislocation. Some HRA-designs have proven good long-term survival rate while others have shown an unacceptable high amount of loosening and been recalled. Yet, for a selected group of patients HRA may be advantageous to THA regarding health-related quality of life. A fundamental prerequisite understanding today's and tomorrow's request on hip arthroplasty is to measure outcomes from patients' perspectives. In this pilot study we compared the patient-reported outcome measures after hip resurfacing with THA using validated general and hip disease specific instruments. A questionnaire was sent to 108 randomly selected patients (72% male) of a cohort of 259 patients (Charnley A+B) who had had uni- or bilateral (two stages) HRA for a period of at least six months. Maximal follow-up time was 7 years. Mean age was 50.2 years (males) and 46.2 years (females) respectively. Patients were reporting EQ-5D and self assessed health-quality (0–100%). In addition, a minor group randomly selected, reported their activity that was graded according to UCLA-activity score. As preoperative EQ-5D baseline, a matched group of 40 patients from the hospital's database scheduled for HRA served.Background:
Methods:
The emerging of non-fusion surgery is aimed to solve the long-term complication of fusion surgery that may bring the adjacent disc degeneration. Among several kinds of artificial discs developed in these years, the majority in the market is Prodisc-L (Synthes Inc.) which is designed with the purpose to restore the motions including anteroposterior translation, lateral bending, and axial rotation. These is also one artificial disc called Physio-L (Nexgen Spine) which were hyper-elastic material (Polycarbonate Polyurethanes) and is designed to restore the motions maintioned above plus axial loading. The concept of using hyper-elastic material as disc is to mimic the material properties of intervetebral discs so that this disc both absorb the axial loading and also restore the physiological range of motion. Few studies focused on the biomechanical behavior of hyper-elastic artificial discs have yet been reported. Therefore, the purpose of this study is to compare the biomechanical behavior between Prodisc-L and Physio-L. A validated three-dimensional finite element model of the L1-L5 lumbar intact spine was used in this study with ANSYS software [Fig.1]. Total disc replacement surgery, partial discectomy, total nuclectomy and removal of the anterior longitudinal ligament were performed at the L3/L4 segment of this intact model, and the Prodisc-L and Physio-L was implanted into L3/L4 segment, respectively. In addition, hyper-elastic materials adopted by Physio-L are usually categorized by their hardness into soft and hard [Fig.2]. Therefore, two kinds of Physio-L were studied. A 400 N follower load and a 10 N-m moment were applied to the intact model to obtain four physiological motions as comparison baseline. The implanted models were subjected to 400 N follower load and specific moments in accordance with the hybrid test method. For the Prodisc-L model in the surgical segment, the range of motion (ROM) varied by -26%, +17%, -0.01%, and -0.04% in flexion, extension, lateral bending, and axial rotation, respectively, as compared to intact model [Fig.3]. For the Physio-L (soft) model, ROM varied by +10%, +8%, +3%, and +19% in four physiological motions, respectively. For the physio-L (hard) model, ROM varied by +1%, +8%, +1%, and +11% in four physiological motions, respectively. For the Prodisc-L model in the adjacent segments, ROM varied by +4% ∼ +10%, -2% ∼ -5%, -1% ∼ -4%, and +1% ∼ -2% in four physiological motions, respectively. For the Physio-L (soft) model, ROM varied by 0% ∼ -5%, -2% ∼ -5%, -0% ∼ -5%, and -9% ∼ -11% in four physiological motions, respectively. For the physio-L (hard) model, ROM varied by +4% ∼ -2%, +8% ∼ -5%, +1 ∼ -5%, and +11% ∼ -6% in four physiological motions, respectively. As seemed in the simulation, the behavior of Physio-L (both soft and hard) is similar to that of intact model under flexion and extension, but not in axial rotation. In addition, Physio-L (hard) model is more similar to intact model as compared to Physio-L (soft) model.
