Recently, the combination of press-fit acetabular cup with ceramic articulation is a widely used for implanting cementless acetabular components and has been shown to provide good initial stability. However, these methods may lead to elevating stresses, changing in the bearing geometries, and increasing wear due to deformation of the cup and insert. In addition, there is a potential for failure of ceramic inserts when a large ball head was used because it should be assembled with shallow thickness of the acetabular cup. For risk reduction of it, we applied direct metal tooling (DMT) based on 3D printing for porous coating on the cup. Due to its capability of mechanical strength, DMT coated cup could be feasible to provide better stability than conventional coating. Therefore, we constructed laboratory models for deformation test simulating an press-fit situation with large ceramic ball head to evaluate stability of the DMT coated cup compared with conventional coated cup. The deformation test was performed according to the test setup described by Z. M. Jin et al. The under reaming of the cavity in a two-point pinching cavity models of polyurethane (PU) foam block (SAWBONES, Pacific Research Laboratories, USA) with a grade 30 were constructed. Titanium plasma spray (TPS) and direct metal tooling (DMT) coated acetabular cups (BENCOX Mirabo and Z Mirabo Cup, Corentec Co. Ltd., KOREA) with a 52 mm size (n=3, respectively) were used for the test. These cups were implanted into the PU foam blocks, and followed by impaction of the inserts (BIOLOX delta, Ceramtec, GE) with a 36/44 size (n=6) into the acetabupar cups as shown in Fig. 1. Roundness and inner diameter of the acetabular cups and inserts were measured using a coordinate measuring machine (BHN 305, Mitutoyo Neuss, GE) in three levels; E2, E3, and E4 (3, 5, and 7 mm below the front face, respectively). Also, these parameters of the acetabular cup were measured in two level; E1 and E5 (5 and 11 mm below the front face) as shown in Fig. 2. Changes in roundness and inner diameter of the cup and insert were measured to evaluate deformation in relation to porous coating on the acetabular cups.Introduction
Materials and Methods
The Rotational alignment is an important factor for survival total knee Arthroplasty. Rotational malalignment causes knee pain, global instability, and wear of the polyethylene inlay. Also, the anterior cortex line was reported that more reliable and more easily identifiable landmark for correct tibial component alignment. The aims of the current study is to identify effect of inserting the tibial baseplate of using anterior cortex line landmark of TKA on stress/strain distributions within cortical bone and bone cement. Through the current study, final aim is to suggest an alternative position of tibia baseplate for reduction of TKA failures with surgical convenience. A three-dimensional tibia FE model with TKA was generated based on a traditional TKA surgical guideline. Here, a commercialized TKA (LOSPA, Corentc, Korea) was considered corresponded to a patient specific tibia morphology. Tibia baseplate was positioned at anterior cortex line. Alternative two positions were also considered based on tibia tuberosity 1/3 line and tibia tuberosity end line known as a gold standard Introduction
Materials and Method
Revision total knee arthroplasy (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone resorption beneath metal block augmentation has been still reported and little information about the reasons of the occurrence of bone resorption is available. The aim of the current study is to identify a possibility of the potential occurrence of bone resorption beneath metal block augmentation, through evaluation of strain distribution beneath metal block augmentation in revision TKA with metal block augmentation, during high deep flexion. LOSPA, revision TKA with a metal block augmentation (Baseplate size #5, Spacer size #5, Stem size Φ9, L30, Augment #5 T5) was considered in this study. For the test, the tibia component of LOSPA was implanted to the tibia sawbone (left, #3401, Sawbones EuropeAB, Malmö, Sweden), which was corresponded to a traditional TKR surgical guideline. The femoral component of LOSPA was mounted to a customized jig attached to the Instron 8872 (Instron, Norwood, MA, USA), which was designed specially to represent the angles ranged from 0° to 140° with consideration of a rollback of knee joint (Figure. 1). Here, a compressive load of 1,600N (10N/s) was applied for each angle. Strain distribution was then measured from rossete strain gauge (Half Bridge type, CAS, Seoul, Korea) together (Figure 1).Introduction
Materials and Method
Cementless arthroplasty has been widely used for younger patients with osteoarthritis and other joint pathology. Cementless arthroplasty will be required to porous surface which is to similar to the trabecular bone for bone ingrowth. Titanium Plasma Spray (TPS) has been worldwide used for the porous coating method on arthroplasty. However, TPS coating is limited that would not to establish optimal porosity for bone ingrowth due to arbitary position of melted powder by plasma gas on substrate. Therefore, it is reported coating detached from its substrate (i.e. arthroplasty) is induced implant loosening. Thus, a novel Laser-aided Direct Metal Tooling (DMT) based on Additive Manufacturing (AM) was developed to overcome these limitations. In this study, we were done to assess stereological analysis, static tensile, shear, abrasion test, and physical analysis for evaluation of the efficacy of DMT which was newly-developed coating technology. Then, mechanical characteristics of DMT coating were compared to commercial TPS coating's. First, porosity of the DMT coating was evaluated using Microphotography and Scanning Electron Microscopy (SEM), as described in Figure 1. Static tensile and shear test for assessment of mechanical characteristic in relation to the DMT and TPS coating specimens were conducted on the basis of ASTM F1147 and F1044 using universal testing machine (Endolab®, Servohydraulic Test Frame, DE). Maximum tensile strength and maximum shear strength were evaluated for each specimen (n=5). Abrasion test was performed based on ASTM F1978 using Taber® Rotary Platform Abraser Model 5135 (TABER®Industries, USA). Abrasion losses for each specimen (n=6) were measured at 2, 5, 10, and 100 cycles, respectively.Introduction
Materials and Methods
Revision total knee arthroplasty (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone defects are frequently detected in revision TKA used with metal block augmentation. This study focused on identification of a potential possibility of the bone defect occurrence through the evaluation of the strain distribution on the cortical bone of the tibia implanted revision TKA with metal block augmentation, during high deep flexion. Composite tibia finite element (FE) model was developed and revision TKA FE model with a metal block augmentation (Baseplate size #5 44AP/67ML, Spacer size #5 44AP/67ML, Stem size Φ9, L30, Augment #5 44AP/67ML thickness 5mm) was integrated with the composite tibia FE model. 0°, 30° 60°, 90°, 120° and 140° flexion positions were then considered with femoral rollback phenomenon [Introduction
Materials and Methods
