INTRODUCTION

Short femoral stem use in total hip arthroplasty (THA) has increased due to positive short-term clinical and biomechanical success. A neck preserving femoral stem not only preserves proximal bone volume, but preserves the high quality bone of the medial neck. The short stem design allows for less invasive surgical exposure and less invasive violation of the femoral canal (Figure 1). Additionally, it facilitates future revision THA, if needed, with a conventional primary stem. The objective of this study was to evaluate the early clinical outcomes of the Alteon® Neck Preserving Femoral Stem (Exactech, Inc.).

METHODS

Forty-nine subjects (25 males, 24 females; mean age: 58.3±7.6 years; mean BMI: 29.8±5.6) from 2 sites underwent primary THA with the Alteon Neck Preserving Femoral Stem. All participants signed the informed consent, and both sites received IRB approval prior to conducting the study. Clinical data outcomes for this study included the Harris Hip Score (HHS), the Oxford Hip Score (OHS), revisions, and subsidence at 3-month, 1-year, and 2-year post-operative time points. Subsidence was measured by an independent third party. Student t-tests were used to identify significant mean differences between genders (p<0.05).

Introduction

Satisfaction and survival rates after total knee arthroplasty were high according to literatures. However, around 8% of revision surgeries were still noted and almost half of them were early failures, which were most seen in 2 years after primary surgery. This study aimed to find out the factors lead to early failures after total knee arthroplasty.

Materials and Methods

Data were collected based on the National Health Insurance Research Data Base of Taiwan from 1996 to 2010. Primary total knee arthroplasty surgeries were included. Revisional total knee arthroplasty, removal of total knee implant and arthrotomy surgeries registered after primary total knee surgeries are seen as failures.

Introduction

A majority of the acetabular shells used today are designed to be press-fit into the acetabulum. Adequate initial stability of the press-fit implant is required to achieve biologic fixation, which provides long-term stability for the implant. Amongst other clinical factors, shell seating and initial stability are driven by the interaction between the implant's outer geometry and the prepared bone cavity. The goal of this study was to compare the seating and initial stability of commercially available hemispherical and rim-loading designs.

Materials and Methods

The hemispherical test group (n=6) consisted of 66mm Trident Hemispherical shells (Stryker, Mahwah NJ) and the rim-loading test group (n=6) consisted of 66mm Trident PSL shells (Stryker, Mahwah NJ). The Trident PSL shell outer geometry is hemispherical at the dome and has a series of normalizations near the rim. The Trident Hemispherical shell outer geometry is completely hemispherical. Both shells are clinically successful and feature identical arc-deposited roughened CpTi with HA coatings on their outer geometry.

Hemispherical cavities were machined in 20pcf polyurethane foam blocks (Pacific Research Laboratories, WA) to replicate the press-fit prescribed in each shell's surgical protocol. The cavity for the hemispherical design was machined to 65mm (1mm-under ream) and the cavity for the rim-loading design was machined to 67mm (1mm- over ream). Note that the rim-loading design features ∼2mm build-up of material at the rim when compared to the hemispherical design.

The shells were seated into the foam blocks using a drop tower (Instron Dynatup 9250G, Instron Corporation, Norwood, MA) by applying 7 impacts of 6.58J/ea,. The number and energy of impacts are clinically relevant value obtained from surgeon data collection through a validated measurement technique. Seating height was measured from the shell rim to the cavity hemispherical equator (top surface foam block) using a height gage, thus, a low value indicates a deeply seated shell.

A straight torque out bar was assembled to the threads at the shell dome hole and a linear load was applied with a MTS Mechanical Test Frame (MTS Corporation, Eden Prairie, MN) to create an angular displacement rate of 0.1 degrees/second about the shell center. Yield moment of the shell-cavity interface, representing failure of fixation, was calculated from the output of force, linear, displacement, and time. Two sample T-tests were conducted to determine statistical significance.

INTRODUCTION

Loosening is a major cause for revision in uncemented hip prostheses due to insufficient primary stability. Primary stability after surgery is achieved through press-fit in an undersized cavity. Cavity preparation is performed either by extraction (removing bone) or compaction (crushing bone) broaching. Densification of trabecular bone has been shown to enhance primary stability in human femora; however, the effect of clinically used compaction and extraction broaches on human bone with varying bone mineral density (BMD) has not yet been quantified. The purpose of this study was to determine the influence of the broach design and BMD on the level of densification at the bone-cavity interface, stem seating, the bone-implant contact area and the press-fit achieved.

METHODS

Paired human femora (m/f=11/12, age=60±18 y) were scanned with quantitative computed tomography (QCT, Philips Brilliance 16) before broaching, with the final broach, after its removal and after stem implantation. Compaction broaching (n=4) was compared in an in situ (cadaver) study against extraction broaching with blunt tooth types (n=3); in an ex situ (excised femora) study, compaction broaching was compared against extraction broaching with sharp tooth types (n=8 each). QCT data were resampled to voxel sizes of 1×1×1 mm (in situ) and 0.5×0.5×1 mm (ex situ). Mean trabecular BMD of the proximal femur was determined. The cavity volumes were segmented in the post-broach images (threshold: −250 mgHA/cm3, Avizo 9.2) and a volume of interest (VOI) of one-voxel thickness was added around the cavity to capture the interfacial bone. VOIs were transferred to the pre-broach image and bone densification was calculated within each VOI as the increase from pre- to post-broach image (MATLAB). Detailed surface data sets of broaches and stems were collected with a 3D laser-scanner (Creaform Handyscan 700) and aligned with the segmented components in the CT scans (Fig. 1). Stem seating was defined as the difference between the top edge of the stem coating and the final broach. Distance maps between the stem and cavity surface were generated to determine the bone-implant contact area and press-fit. All parameters were analysed between 5 mm distal to the coating and 1 cm distal to the lesser trochanter and analysed with related-samples Wilcoxon signed rank and Spearman's correlation tests (IBM SPSS Statistics 22).

Introduction

Modern acetabular cups require a convenient bone stock for sufficient cup fixation. Thereby, fixation stability is influenced by the chosen interference fit of the acetabular cup, the cup surface structure, circularity of the reamed acetabulum and by the acetabular bone quality. The ideal implantation situation of the cup is commonly compromised by joint dysplasia and acetabular bone defects. The aim of the present experimental study was to characterise implant fixation of primary acetabular cups in case of definite acetabular cavity defects.

Materials and Methods

For the experimental determination bone substitute blocks (100 × 100 × 50 mm) made of polymethacrylimide (PMI) foam with a density of 7 pcf were used. The created acetabular defect situations were derived from the defect classification according to Paprosky. The defect geometries in the PMI foam blocks were realised by a CNC drilling machine. Thereby the defects are described in the dorso-ventral direction by the angle α and in medio-lateral direction by the angle β (given as angle combination α/β) related to the centre of rotation of the reamed cavity. For the lever-out tests the defect types IIb and IIIa (each with different α and β angles) were considered and compared to the intact fixation situation. Therefore, a macrostructured titanium cup (Allofit, Zimmer GmbH, Wintherthur, Switzerland) with an outer diameter of 56 mm were displacement-controlled (v = 20 mm/min) pushed into the 2 mm diametric under reamed PMI-foam cavities. Three cups were inserted until the cup overhang pursuant to surgical technique was reached. Subsequently the cups were displacement-controlled (v = 20 mm/min) levered out via a rod which was screwed into the implant pole by perpendicular displacement (U_axial) of the rod in direction of the defect aperture. The lever-out moments were calculated by multiplying the first occurring force maximum (F_max) with the effective lever arm length (l_lever), whereby moments caused by the deadweight of the rod were considered. Primary stability was defined by the first maximum lever-out moment.

Introduction

Experimental wear simulation of an all-polymer knee implant has shown an equivalent rate of wear of UHMWPE tibial components against PEEK-OPTIMA™ and cobalt chrome femoral components of a similar initial geometry and surface topography. However, when the patella is resurfaced with an UHMWPE patella button, it is important to also ascertain the wear of the patella. Wear debris from the patella contributes to the total volume of wear debris produced by the implant which should be minimised to reduce the potential for osteolysis and subsequent implant loosening. The aim of this study was to investigate the wear of the patellofemoral joint in an all-polymer knee implant. The wear of UHMWPE patellae articulating against PEEK-OPTIMA™ femoral components was compared to UHMWPE articulating against cobalt chrome femoral components.

Materials and Methods

Six mid-size (size C) PEEK-OPTIMA™ femoral components (Invibio Knee Ltd., UK) and six cobalt chrome femoral components of similar initial surface topography and geometry were coupled with 28mm all-polyethylene GUR1020 patellae (conventional, EO sterile) (Maxx Orthopaedics, USA). The implants were set up in a ProSim 6 station electromechanical knee simulator (Simulation Solutions, UK) which was modified for testing the patellofemoral joint. 3 million cycles (MC) of wear simulation was carried out under kinematics aiming to replicate a gait cycle adapted for an electromechanical simulator from previous work by Maiti et al. The simulator used has six degrees of freedom of which four were controlled; axial force up to 1200N, flexion/extension 22°, superior-inferior (SI) displacement (22mm) and Abduction-adduction (AA) (4°). The SI and AA were displacement controlled and driven through the patella. The medial-lateral displacement and tilt (internal/external rotation) of the patella were passive so the patella button was free to track the trochlear groove. The lubricant used was 25% bovine serum supplemented with 0.03% sodium azide to retard bacterial growth. The wear of patellae was determined gravimetrically with unloaded soak controls used to compensate for the uptake of moisture by the UHMWPE. The mean wear rate ± 95% confidence limits were calculated and statistical analysis was carried out using ANOVA with significance taken at p<0.05.

Introduction

PEEK-OPTIMA™ has been considered as an alternative bearing material to cobalt chrome in the femoral component of total knee replacements. To better understand the tribology of UHMWPE-on-PEEK-OPTIMA™ and to find the most appropriate environmental conditions under which to test this novel bearing material combination, a series of tests under different protein lubricant concentrations at rig (∼24°C) and elevated temperature (∼35°C) were carried out in simple geometry wear and friction rigs. Under all conditions, the wear of UHMWPE-on-PEEK-OPTIMA™ was compared to UHMWPE-on-cobalt chrome (CoCr).

Methods

The pins used were GUR1020 UHMWPE (conventional, non-sterile) and the plate material was either polished CoCr (Ra<0.01µm) or PEEK-OPTIMA (Ra∼0.03µm) provided by Invibio Ltd, UK. The wear simulation was carried out in a six station reciprocating rig. The kinematic conditions were consistent for all tests and reflected the average cross shear and contact pressure (3.2MPa) in a total knee replacement. Tests were carried out at either rig running temperature (∼24°C) or at elevated temperature (∼35°C) and in varying protein lubricant concentrations (0, 2, 5, 25 and 90%). Wear of the UHMWPE pins was determined by gravimetric analysis. The pin-on-plate friction rig study was carried out at rig temperature in 0, 2, 5, 25 and 90% serum and reflected the contact pressure used in the wear tests. Measurements were taken using a piezoelectric sensor and the steady state friction derived. At least 3 repeats were taken for each study, statistical analysis carried out using ANOVA with significance taken at p<0.05.

Purpose

To evaluate the radiographic long-term result of femoral revision hip arthroplasty using impacted cancellous allograft combined with cemented, collarless, polished and tapered stem.

Materials and methods

Among 28 patients with impacted cancellous allograft with a cemented stem, 28 hips from 26 consecutive patients were analyzed retrospectively. The average patient age was 59 years. The follow-up period ranged 9 years 6 months to 14 years 5 months (mean, 12, 5 years). Radiographic parameters analyzed in this study included subsidence of the stem in the cement, subsidence of the cement mantle in the femur, bone remodeling of the femur, radiolucent line, and osteolysis.

Introduction

Optimal implant position is critical to hip stability after total hip arthroplasty (THA). Recent literature points out the importance of the evaluation of pelvic position to optimize cup implantation. The concept of Functional Combined Anteversion (FCA), the sum of acetabular/cup anteversion and femoral/stem neck anteversion in the horizontal plane, can be used to plan and control the setting of a THA in standing position. The main purpose of this preliminary study is to evaluate the difference between the combined anteversion before and after THA in weight-bearing standing position using EOS 3D reconstructions. A simultaneous analysis of the preoperative lumbo pelvic parameters has been performed to investigate their potential influence on the post-operative reciprocal femoro-acetabular adaptation.

Material and Methods

66 patients were enrolled (unilateral primary THAs). The same mini-invasive anterolateral approach was performed in a lateral decubitus for all cases. None of the patients had any postoperative complications. For each case, EOS full-body radiographs were performed in a standing position before and after unilateral THA. A software prototype was used to assess pelvic parameters (sacral slope, pelvic version, pelvic incidence), acetabular / cup anteversion, femoral /stem neck anteversion and combined anteversion in the patient horizontal functional plane (the frontal reference was defined as the vertical plane passing through centers of the acetabula or cups). Sub-analysis was made, grouping the sample by pelvic incidence (<55°, 55°–65°, >65°) and by pre-operative sacral slope in standing position (<35°, 35°–45°, >45°). Paired t-test was used to compare differences between preoperative and postoperative parameters within each subgroup. Statistical significance was set at p < 0.05.

Introduction

Understanding hip-spine relationships and accurate evaluation of the pelvis position are key- points for the optimization of total hip arthroplasty (THA). Hip surgeons know the importance of pelvic parameters and the adaptation mechanisms of pelvic and sub-pelvic areas. Literature about posture after THA remains controversial and adaptations are difficult to predict. One explanation can be the segmental analysis focused on pelvic parameters and local planning.

In a significant number of patients a global analysis may be important as a cascade of compensatory mechanisms is implemented, the hip being only one of the links of this chain reaction.

3 parameters can be measured on full body images:

The objective of this preliminary study is to report the post-operative evolution of posture after THA.

Material and Method

49 patients (28 women, 21 men, mean age 61 years) were enrolled for full-body standing EOS images before and after THA. The sterEOS software was used to measure pelvic parameters (sacral slope SS, pelvic incidence PI) and global postural parameters (TPA, GSA, SVA).

Sub-analysis was made, grouping the sample by TPA (<14°, 14°–22°, >22°), by PI (<55°, 55°–65°, >65°) and by SS (<35°, 35°–45°, >45°). Paired t-test was used to compare differences between preoperative and postoperative parameters within each subgroup. Statistical significance was set at p < 0.05.

Introduction

Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery.

Material and methods

65 THA were performed in 59 patients (34 men, 25 women, mean age 73 years, 55–79). Mean latest follow-up was 8,3 years (4–14). Indications were 42 primary THA (osteoarthrosis) and 21 revisions (11 recurrent dislocation, 6 acetabular PE wear, 4 femoral loosening). Surgical approach was always antero-lateral. All patients were implanted with the same dual mobility cementless cup. The same cementless corail-type stem was used for primary THA cases. All the cemenless implants were hydroxyapatite coated. The disability caused by the disease was classified according to Hoehn and Yahr. (19 stage 1, 21 stage 2,16 stage 3)

BACKGROUND

Stability of the glenoid component is essential to ensure successful long-term outcomes following Total shoulder arthroplasty (TSA), and may be improved through better glenoid component design. As such, this study assessed identical all-polyethylene glenoid components stability, having various fixation types, using component micromotion under simulated joint loading in an osteoarthritic patient cohort.

METHODS

Five all-polyethylene glenoid component designs were compared (Keel, Central-Finned 4-Peg, Peripheral 4-Peg, Cross-Keel, and Inverted-Y). A cement mantle surrounded each fixation type, except the Central-Finned 4-Peg which was surrounded by bone. The humeral component had a non-conforming radius of curvature. Scapular models of six type A1 osteoarthritic male patients (mean: 61 years old, range: 48 to 76 years old) were assigned heterogeneous bone properties based on CT intensity. Each of the 30 scapula models were truncated and fully constrained on the medial scapular border. The bone/cement interface was fully bonded, and the fixation feature/cement interface was frictionally constrained. A ‘worst case’ load magnitude of 125% BW of a 50th percentile male was used. A purely compressive load was applied to the center of the glenoid component, followed by superior, superior-posterior, posterior, inferior-posterior, and inferior loads. Stability of the glenoid component based solely on the fixation type was determined using the mean and maximum normal (liftoff) and tangential (sliding) micromotion in six regions of the glenoid component.

Background

Total Hip Arthroplasty (THA) has long been the standard treatment for cases in which non-surgical alternatives have failed to improve pain and function in hip osteoarthritis (OA) patients. Outcomes from THA have improved over time with better surgical techniques and improved implant designs. While conventional neck-sacrificing implants have been associated with favorable outcomes, there is evidence to suggest biomechanical advantages of newer, femoral neck-preserving short-stem implants, including the Corin MiniHip. However, there is a still a gap of knowledge regarding the potential benefits of the MiniHip stem over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). In this study, we investigated the differences between a neck-sacrificing stem design and neck-preserving short-stem design (MiniHip, Corin Inc.) arthroplasty concerning PROs, and considering the known features of the short stem design, we hypothesized that MiniHip THA would be associated with improved PROs in comparison to a neck-sacrificing implant system. We further sought to investigate gender effects related to MiniHip or conventional stem surgery.

Methods

Neck-sacrificing implant patients (n=90, age 57±7.9 years, female=58, male=32) and a matched (matching criteria: follow-up period, BMI, age) cohort group of MiniHip patients (n=105, age 55.16±9.88 years, female: 25, male: 80) reported both pre-operative and post-operative Hip disability and Osteoarthritis Outcome Scores (HOOS) at a minimum interval of 6 months post-operatively and up to three years postoperatively. We applied MANCOVA analysis to compare patient-reported outcome subscores from each group using follow-up period as a covariate and employing gender as an additional grouping factor to evaluate gender effects. Statistical significance was set at α=0.05 and Bonferroni corrections were applied to account for multiple comparisons.

INTRODUCTION

Accurate knowledge of knee joint kinematics following total knee arthroplasty (TKA) is critical for evaluating the functional performance of specific implant designs. Biplane fluoroscopy is currently the most accurate method for measuring 3D knee joint kinematics in vivo during daily activities such as walking. However, the relatively small imaging field of these systems has limited measurement of knee kinematics to only a portion of the gait cycle. We developed a mobile biplane X-ray (MoBiX) fluoroscopy system that enables concurrent tracking and imaging of the knee joint for multiple cycles of overground gait. The primary aim of the present study was to measure 6-degree-of-freedom (6-DOF) knee joint kinematics for one complete cycle of overground walking. A secondary aim was to quantify the position of the knee joint centre of rotation (COR) in the transverse plane during TKA gait.

METHODS

Ten unilateral posterior-stabilised TKA patients (5 females, 5 males) were recruited to the study. Each subject walked over ground at their self-selected speed (0.93±0.12 m/s). The MoBiX imaging system tracked and recorded biplane X-ray images of the knee, from which tibiofemoral kinematics were calculated using an image processing and pose-estimation pipeline created in MATLAB. Mean 6-DOF tibiofemoral joint kinematics were plotted against the mean knee flexion angle for one complete cycle of overground walking. The joint COR in the transverse plane was calculated as the least squares intersection of the femoral flexion axis projected onto the tibial tray during the stance and swing phases. The femoral and tibial axes and 6-DOF kinematics were defined in accordance with the convention defined by Grood and Suntay in 1983.

Introduction & Background

Clinical outcome after reverse total shoulder arthroplasty (RTSA) can be influenced by technical and implant-related factors, so the purpose of this study was to investigate whether individualizing humeral retroversion and subscapularis repair affect the clinical outcomes after RTSA.

Material & Method

Authors retrospectively analyzed the prospectively collected data from 80 patients who underwent RTSA from January 2007 to January 2015 using same implant (Biomet Comprehensive^® Reverse Shoulder System, Warsaw, Indiana). The mean follow up was 23.3 ± 1.7 (range, 12 ∼ 70) months. The retroversion of humeral component was decided according to native version estimated using shoulder CT in Group I (n=52), and fixed in 20° retroversion in Group II (n=28). Group I was subdivided into Group Ia (n=21, mean 19.3°), less than 20° of retroversion, and Group Ib (n=31, mean 31.9°), more than 20°. Intraoperative tenotomized subscapularis was repaired in 40 patients in Group I, and could not be repaired due to massive tear including subscapularis in remaining 12 patients. Clinical outcomes were evaluated with range of motion (ROM) and several clinical outcome scores.

Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in the human body after total joint replacement causes serious clinical and biomechanical reactions. Therefore, the wear phenomenon of UHMWPE is now recognized as one of the major factors restricting the longevity of artificial joints. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE.

Materials and Methods

In a previous study (Cho et al., 2016), it was found that roundness (out-of-roundness) of the retrieved UHMWPE acetabular cup liner [Figure 1(a)] had a tendency to increase with increasing roundness of the retrieved metal femoral head [Figure 1(b)]. It appears that roundness of the femoral head contributes to increase of wear of the polyethylene liners. We focused on the roundness of femoral head as a factor influencing the wear of polyethylene liner in hip prosthesis. In this study, further roundness measurements for 5 retrieved metal femoral heads were performed by using a coordinate measuring machine. The elasto-plastic contact analyses between femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the influence of femoral head roundness on the mechanical state and wear of polyethylene liner in hip prosthesis.

Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in knee and hip prostheses after total joint replacement is one of the major restriction factors on the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear of UHMWPE. A number of studies have investigated the factors influencing the wear of UHMWPE acetabular cup liner in hip prosthesis. Most of these studies, however, have focused on the main articulating surfaces between the femoral head and the polyethylene liner.

Materials and Methods

In a previous study (Cho et al., 2016), the generations of cold flow into the screw holes in the metal acetabular cup were observed on the backside of the retrieved UHMWPE acetabular cup liners as shown in Figure 1. We focused on the screw holes in the metal acetabular cup (Figure 2) as a factor influencing the wear behavior of polyethylene liner in hip prosthesis. In this study, computer simulations of the generation of cold flow into the screw holes were performed using the finite element method (FEM) in order to investigate the influence of the screw holes in the metal acetabular cup on the mechanical state and wear behavior of polyethylene liner in hip prosthesis.

Introduction

Wear phenomenon of ultra-high molecular weight polyethylene (UHMWPE) in hip and knee prostheses is one of the major restriction factors on the longevity of these implants. In retrieved hip prostheses with screw holes in the metal acetabular cup for fixation to the pelvis, the generation of cold flow into the screw holes is frequently observed on the backside of the UHMWPE acetabular cup liner. In most retrieved cases, the protruded areas of cold flow on the backside were located on the reverse side of the severely worn and deformed surface of the polyethylene liner. It would appear that the cold flow into screw holes contributes to increase of wear and damages of the polyethylene liner in hip prosthesis.

Methods

In a previous study (Cho et al., 2016), we pointed out the generation of cold flow into the screw holes on the backside of the retrieved UHMWPE acetabular cup liner as shown in Figure 1. The primary purpose of this study was to investigate the influence of the cold flow into the screw holes on the wear of the polyethylene liner in hip prosthesis. In this study, computer simulations of the generation of cold flow were performed using the finite element method (FEM) in order to propose the design criteria about the cold flow of the hip prosthesis for improving the wear resistance of the polyethylene liner. We especially focused on the influence of polyethylene thickness and contact surface conformity on the generation of cold flow into the screw hole.

Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE and the polyethylene wear debris generated in the human body after total joint replacement cause serious clinical and biomechanical reactions.

Therefore, the wear phenomenon of UHMWPE in total joint replacement is now recognized as one of the major factors restricting the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE.

Materials and Methods

The wear and/or failure characteristics of 33 retrieved UHMWPE acetabular cup liners of hip prostheses were examined in this study. The retrieved liners had an average in vivo duration of 193.8 months (75 to 290 months). Several examples of the retrieved liners are shown in Figure 1. The elasto-plastic contact analyses between metal femoral neck and polyethylene liner and between metal femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the factors influencing the wear and/or failure mechanism of the polyethylene liner in hip prosthesis.

Introduction

Stiffness post Total Knee Replacement (TKR) is a common, complex and multifactorial problem. Many reports claim that component mal-rotation plays an important role in this problem. Internal mal-rotation of the tibial component is underestimated among surgeons when compared to femoral internal mal-rotation. We believe the internal mal-rotation of the tibial component can negatively affect the full extension of Knee. We performed an in-vivo study of the impact of tibial internal mal-rotation on knee extension in 31 cases.

Method

During TKR, once all bony cuts were completed and flexion/extension gaps balanced, we assessed the degree of knee extension using the trial component in the setting of normal tibial rotation and with varying degrees of internal rotation (13–33°, mean 21.2±4.6°). Intra-operative lateral knee X-ray was done to measure the degree of flexion contracture in both groups. We also compared the degree of flexion contracture between CR and PS spacers.

Introduction

Early complication post total knee replacement reported to be higher in obese patient in general. Also the outcome of cruciate retaining and PS knee has been fully discussed before and there was no major difference in the outcome. However, the purpose of this paper is to find out if early complication postTKR such as fracture and instability is more common in PS implant than in CR knee. This is a retrospective study comparing two groups of obese patients. The first using PS implant and the other using CR implant. These two groups were matched for age, body mass and severity of deformity. We clearly showed that there is significant increase in peri-prosthetic fracture and instability in the group that use PS implant.

Materials & Methods

At our institution we have been using Persona implant which has the option of using PS insert or a CR. The decision to proceed with CR or PS mainly depends on the availability of the implant and also the ability to well balance the knee in patients. In most patients we try to proceed with CR implant. However, the flow of implant sometime sometimes limit us from using CR or the imbalance in the ligament force us to process with PS implant.

We have reviewed a chart of over 200 patients in each group of obese patient they were done within the last three years. All cases had a minimum follow up of 6 months. Those groups were matched for body mass, age and severity of deformity. After matching the groups we documented knee score, blood loss, post – operative pain and complications. All surgeries were performed by the same surgeon.

Introduction

The convincible wisdom is that the release of MCL in severe varus knee should be progressive. This release is usually carried on after resecting the osteophyte and gradually carried on until the MCL is well balanced. However, sometimes, extensive release and releasing the superficial MCL can lead to instability in flexion. On a personal communication with many Asian surgeons they have been doing a careful release of the posteromedial corner in the varus knee and in majority of cases such release is adequate. And even in severe cases of varus knee superficial MCL doesn't need to be released.

20 total knee replacements were performed by the same surgeon using ZimmerPS implant. In the varus deformity ranges from 15–35 degrees. The first bony section was made carefully. All osteophytes were removed and resected. The posterior bone osteophytes were also resected and the intercondylar notches were made along with the posterior release. After doing the bony cut in 18 of those cases the medial compartment was still tight and both flexion and extension

A careful release was carried in the postal medial corner-First using an osteotome around the posteromedial corner to release the soft tissue. After that the thick fibrous tissue that formed like pseudo meniscus was also resected until we were able to reach the posterior capsule. In some cases those scar tissues even extended to the capsule requiring the resecting of the postal medial capsule. We meticulously resected all those scar tissues and in many of those cases were able to visualize the MCL ligament which was well preserved. A tensioning device was used before and after the release. In all of those cases we were able to document an opening ranging from two to seven millimeter after the proper release. In all cases the superficial MCL were still intact and can be operated carefully

Result

This study clearly shows that we did not have to release the superficial MCL and the careful posteromedial release was adequate to obtain a good balance gap immediately and the knee was quite stable. The superficial MCL was maintained and preserved and tensioning device clearly document opening after releasing the postural medial corner

INTRODUCTION

In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface (Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee.

MATERIALS AND METHODS

23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150 degree).

Introduction

3 main challenges encountered in knee revision of Asians:

Therefore we like to alert surgeon apprehending enhanced challenges while indulging in revision of Asian.

Our emiratus author with USA background/qualification/experience has excuted 216 revision in 8yrs with at least 3yrs follow-up.

Material & Method

Between 2003–2010 we performed 216 revision TKR, reviewed all parameters & compared our results with European revision statistics depicting a) intermedullary canal smaller b) metaphysis narrower & more triangular in comparision to Caucasian causing housing mechanism fit impossible, also increase impingment of stem at times.

Bone loss is normally quiet extensive & available implant including the Tantalum cone sometimes is difficult to fit in a tight metaphyseal area, we had satisfactory outcome inspite of owing to intra-operative complication which lead to 3 intramedullary fracture resulting from inadequate avalibity of smaller size, incomplete seating of tibial component, overhang of femoral component.it also leads to more translucent line quoted in 15 cases.

Centre of IM canal in both tibia & femur is positioned more posteriorly especially in smaller size proven by CT anatomical study analysis.

These data we related to anatomic variance rather then surgical technique therefore representing deficit of proper size thereby contributing to inability to surgeon.

Introduction

The volume of intraoperative blood loss is measured and reported by OR nurses in many hospitals and doctors do not usually measure it by themselves. To measure intraoperative blood loss accurately is such a difficult task that many measurement errors occur due to various factors. However, it is important to obtain a more correct measurement for performing a safe operation and stable anesthesia control.

Case report

In total hip arthroplasty (THA) we had experienced massive intraoperative blood loss errors and later identified the two major causes of these errors.

One is the excess volume of infusions for irrigation infusions, and the other is the validity and reliability of the scales on infusion containers.

To accurately measure intraoperative blood loss, we should know these two important factors of intraoperative blood loss errors.

In arthroplasty we use many infusions for irrigation of the operative field. The labeled (nominal) volume of infusion containers do not accurately indicate the volume of infusions in the container. This is even defined by the WHO international pharmacopoeia (pharmaceutical laws), US, EU, and Japanese pharmacopoeia. According to these pharmacopoeia, the actual volume of infusions is (must be) not less than the labeled (nominal) volume. Moreover, the upper limit of excess volume is not regulated so far. This results in all parenteral infusions (i.e., I.V infusion bags, or bottles of saline) having excess volume compared to their respective labeled volumes.

We also have verified the accuracy of volume scales on the infusions bags and bottles and found out some products have inaccuracies that we cannot ignore.

After inquiring the pharmaceutical companies about the information concerning excess volume of infusions, we discovered that the excess volume is 2–5% higher than the labeled (nominal) volume depending on the product and company. (e.g., One product has around 3140ml in the container labeled 3000ml)

Objective

This paper aims to analyze the kinetics of the over-ground wheel-type body weight supporting system (BWS); tendency changes of low extremity joint moment (hip, knee, ankle), 3 axis accelerations of a trunk, cadence and gait velocity as weight bearing level changes.

Method

15 subjects (11 males, 4 females, age:23.63.5, height:170.65.1cm, weight:69.0210.75kg) who had no history of surgery participated. 6 levels (0%, 10%, 20%, 30%, 40% and 50%) of BWS were given to subjects at self-selected gait velocity and kinetic data was calculated using a motion capture system, Vicon^® (Vicon, UK).

Introduction

Bicruciate-retaining (BiCR) total knee replacements (TKRs) were designed to improve implant performance; however, functional advantages during daily activity have yet to be demonstrated. Although level walking is a common way to analyze functionality, it has been shown to be a weak test for identifying gait abnormalities related to ACL pathologies. The goal of this study is to set up a functional motion analysis test that will examine the effects of the ACL in TKR patients by comparing knee kinematics, kinetics, and muscle activation patterns during level and downhill walking for patients with posterior-cruciate retaining (PCR) and BiCR TKRs.

Methods

Motion and electromyography (EMG) data were collected simultaneously for 12 subjects (4/8 m/f, 64±11 years, 31.3±7.3 BMI, 6/6 right/left) with BiCR TKRs and 15 subjects (6/9 m/f, 67±7 years, 30.5±5.1 BMI, 4/11 right/left) with PCR TKRs during level and downhill walking using the point cluster marker set. Surface electrodes were placed on the vastus medialis obliquus (VMO), rectus femoris (RF), biceps femoris (BF), and semitendinosus (ST) muscles. EMG data are reported as percent relative voluntary contraction (%RVC), normalizing the signal during downhill walking to the mean maximum EMG value during level walking.

Background

The reductions of perioperative blood loss and inflammatory response are important in total knee arthroplasty. Tranexamic acid reduced blood loss and the inflammatory response in several studies. However, the effect of epinephrine administration plus tranexamic acid has not been intensively investigated, to our knowledge. In this study, we evaluated whether the combined administration of low-dose epinephrine plus tranexamic acid reduced perioperative blood loss or inflammatory response further compared with tranexamic acid alone.

Methods

This randomized placebo-controlled trial consisted of 179 consecutive patients who underwent primary total knee arthroplasty. Patients were randomized into 3 interventions: Group IV received intravenous low-dose epinephrine plus tranexamic acid, Group TP received topical diluted epinephrine plus tranexamic acid, and Group CT received tranexamic acid alone. The primary outcome was perioperative blood loss on postoperative day 1. Secondary outcomes included perioperative blood loss on postoperative day 3, coagulation and fibrinolysis parameters (measured by thromboelastography), inflammatory cytokine levels, transfusion values (rate and volume), thromboembolic complications, length of hospital stay, wound score, range of motion, and Hospital for Special Surgery (HSS) score.

Purpose

Unicompartmental Knee Arthroplasty (UKA) has been indicated for inactive elderly patients over 60, but for young and active patients less than 60 years old, it has been regarded as a contraindication. The purpose of this study is to evaluate the usefulness of UKA performed on young Asian patients under 60 years of age by analyzing clinical outcomes, complications and survival rate.

Materials and Methods

The subjects were 82 cases, which were followed up for at least 5 years (from 5 to 12 years). Only Oxford phase III® (Biomet Orthopedics, Inc, Warsaw, USA) prosthesis was used for all cases. The clinical evaluation was done by the range of motion, Knee society score (KSS), WOMAC score. The radiographic evaluation was performed on weight bearing long-leg radiographs, AP and lateral view of the knee and skyline view of the patella. The survival rate was estimated by Kaplan-Meier survival analysis.

INTRODUCTION

The results of modified gap balancing and measured resection technique have been still controversial. We compared PS-type TKAs for osteoarthritis performed using the modified gap technique and the measured resection to determine if either technique provides superior clinical results.

METHODS

The modified gap technique was used in 85 knees, and the measured technique using preoperative CT was used in 70 knees. To compare intra-operative soft tissue balance, bone gap and component gap were measured using original two paddle tensor (20,30,40lb) at 0 degree extension and 90 degrees flexion. To assess the post-operative patella congruency and soft tissue balance, we measured patella tilt, condylar twist angle (CTA) and condylar lift-off angle (LOA) in radiographs. Finally, we evaluated postoperative clinical result (1–5 years) KOOS. Statistical analysis was used by StatView.

Introduction and Aims

There are many surgical, implant design and patient factors that should be considered in preclinical testing of hip replacement which are not being considered in current standards. The aim of this study was to develop a preclinical testing method that consider surgical positioning, implant design and patient factors and predict the occurrence and severity of edge loading under the combination of such conditions. Then, assess the safety and reliability of the implant by predicting the wear, deformation and damage of the implant bearings under worst case conditions.

Methods

Ceramic-on-ceramic (CoC, 36mm, BIOLOX^® delta, Pinnacle^®, DePuy Synthes, UK) and metal-on polyethylene (MoP, 36mm, Marathon®, Pinnacle^®, DePuy Synthes, UK) bearings were used for this study on multi-station multi-axis hip joint simulators. Two factors were varied, cup inclination angles (45° and 65°) and translational mismatch between the femoral head and acetabular cup (0, 2, 3 and 4 (mm)). Under each condition for both CoC and MoP bearings, three million cycles of gait cycle testing were completed with wear, deformation and/or damage measurements completed at one million cycle intervals. Other outputs of the study were the level of dynamic separation between the femoral head and acetabular cup during gait, the maximum force at the rim during edge loading when the head was sliding back to the cup confinement. Means and 95% confidence limits were determined and statistical analysis were done using one way ANOVA with significance taken at p<0.05.

Introduction

Frictional behavior and, therefore, the coefficient of friction (CoF) play an important role in the evolution of fretting wear. Several studies investigated fretting at the ball head-taper junction with a remarkable variation in the CoF (0.15 to 0.55). This may be due to different material couplings, surface topographies or macro-geometries. Since the results of Finite Element (FE) models are strongly dependent on the choice of CoF it is crucial to determine the correct CoF for a speci?c system. Therefore, this study aimed to determine the CoF for the interface between ceramic ball heads and metal tapers.

Materials and Methods

Three groups of taper-ball head couplings were investigated (n=18 titanium (Ti), n=18 cobalt chromium (CoCr), n=18 steel tapers (SS)). Line profiles of the taper surfaces were measured and tapers and ball heads were assembled using different loads (2, 4, 6 kN). Tapers were disassembled from ball heads by using liquid nitrogen, surface topography was remeasured and the effective contact area was determined. Another set of measurements was conducted (n=5 tapers per taper material) to measure the contact pressure. Here, pressure sensitive films were placed between tapers and ball heads during assembly. Using the effective contact area and contact pressure the CoF was calculated.

Background

Extensive research has previously been conducted analyzing the biomechanical effects of rotational changes (i.e. version and inclination) of the acetabular cup. Many sources, citing diverse dislocation statistics, encourage surgeons to strive for various “safe zones” during the THA operation. However, minimal research has been conducted, especially under in vivo conditions, to assess the consequences of cup translational shifting (i.e. offsets, medial and superior reaming, etc.). While it is often the practice to medialize the acetabular cup intraoperatively, there is still a lack of information regarding the biomechanical consequences of such cup medializations and medial/superior malpositionings.

Objective

Therefore, the objective of this study is to use a validated forward solution mathematical model to vary cup positioning in both the medial and superior directions to assess simulated in vivo kinematics.

Background

In vivo fluoroscopic studies have proven that femoral head sliding and separation from within the acetabular cup during gait frequently occur for subjects implanted with a total hip arthroplasty. It is hypothesized that these atypical kinematic patterns are due to component malalignments that yield uncharacteristically higher forces on the hip joint that are not present in the native hip. This in vivo joint instability can lead to edge loading, increased stresses, and premature wear on the acetabular component.

Objective

The objective of this study was to use forward solution mathematical modeling to theoretically analyze the causes and effects of hip joint instability and edge loading during both swing and stance phase of gait.

Introduction

Offset femoral broach handles have become more common as the anterior approach in total hip arthroplasty has increased in popularity. The difference in access to the femur compared to a posterior approach necessitates anterior and, in some cases, lateral offsets incorporated into the design of the broach handle to avoid interference with the patient's body and to ensure accessibility of the strike plate.

Using a straight broach handle with a primary stem, impaction force is typically directed along the axis of the femoral broach. However, the addition of one or more offsets to facilitate an anterior approach results in force transmission in the transverse plane, which is unnecessary for eating the femoral broach. The direction of forces transmitted to the broach via strike plate impaction can introduce a large moment. A negative consequence of this moment is the amplification of stresses/strains at the bone/broach interface, which increases the likelihood of femoral fracture during impaction.

It was proposed that optimizing the angle of the strike plate could minimize the moment to reduce the unintended stresses/strains at the bone/broach interface.

Objectives

The objective was to minimize the stresses/strains imparted to the proximal aspect of the bone femur when broaching with a given dual offset broach handle design.

Purpose

Management and outcomes of fungal periprosthetic joint infection (PJI) remain unclear due to its rarity. Although two-stage exchange arthroplasty is considered a treatment of choice for its chronic features, there is no consensus for local use of antifungal agent at the 1st stage surgery. The purpose of this study was to evaluate the efficacy of antifungal-impregnated cement spacer in two-stage exchange arthroplasty against chronic fungal PJIs after total knee arthroplasty (TKA).

Methods

Nine patients who were diagnosed and treated for chronic fungal PJIs after TKA in a single center from January 2001 to December 2016 were enrolled. Two-stage exchange arthroplasty was performed. During the 1st stage resection arthroplasty, amphotericin-impregnated cement spacer was inserted for all patients. Systemic antifungal medication was used during the interval between two stage operations. Patients were followed up for more than 2 years after exchange arthroplasty and their medical records were reviewed.

Introduction

Both measured resection technique and gap balancing technique have been important surgical concepts in total knee arthroplasty (TKA). Modified gap technique has been reported to be beneficial for the intra-operative soft tissue balancing in posterior-stabilizing (PS) -TKA.

On the other hand, we have found joint distraction force changed soft tissue balance measurement and medial knee instability would be more likely with aiming at perfect ligament balance at extension in modified gap technique. The medial knee stability after TKA was reported to essential for post-operative clinical result.

We have developed a new surgical concept named as “medial preserving gap technique” for varus type osteoarthritic (OA) knees to preserve medial knee stability and provide quantitative surgical technique using tensor device.

The purpose of this study was to compare post-operative knee stability between medial preserving gap technique (MPGT) and measured resection technique (MRT) in PS-TKA.

Material & Method

The subjects were 140 patients underwent primary unilateral PS-TKA for varus type OA knees. The surgical technique was MPGT in 70 patients and MRT in 70 patients. There were no significant differences between two groups in the pre-operative clinical features including age, sex, ROM and deformity.

Originally developed off-set type tensor device was used to evaluate both center gap and varus angle with 40 lbs. of joint distraction force. The extension gap preparation was identical in both group. In MPGT group, femoral component size and external rotation angle were adjusted depending on the differences of center gaps and varus angles between extension and flexion before posterior femoral condylar osteotomy.

The knee stabilities at extension and flexion were assessed by stress radiographies; varus-valgus stress test with extension and stress epicondylar view with flexion, at one-month and one-year after TKA. We measured joint opening distance (mm) at medial and lateral compartment at both knee extension and flexion.

Joint opening distances were compared between two groups using unpaired t-test, and the difference between medial and lateral compartment in each group was compared using paired t- test (p<0.05).

Background

Knee osteoarthritis (OA) is a major cause of ambulatory disabilities. Although total knee arthroplasty (TKA) has been reported as the most effective treatment for severe knee OA, quantitative evaluation of ambulatory function have not been well investigated.

We hypothesized that better functional recovery would result in better patient satisfaction. The purpose of this study was to quantitatively evaluate ambulatory functional recovery and assess the influence on patient satisfaction after TKA.

Material and Methods

90 patients (80 females and 10 males) were involved in this study. The mean age at TKA was 75.2 ± 5.8 years. Patients were subjected to 3 meters timed up and go test (TUG) to evaluate ambulatory function. TUG was performed at 6 time periods; before surgery, 2 weeks, 1, 3, 6 months, and 1 year after surgery. We also asked the patients to fill out the questionnaire of patient satisfaction category in the New Knee Society Score at 1 year after TKA.

The sequential changes in TUG were analyzed using repeated measures ANOVA (p<0.05). The influences of each parameter (age, TUGs) on the patient satisfaction score were analyzed with simple regression analysis (p<0.05).

Introduction

Limb length discrepancy (LLD) is one of the major reasons of dissatisfaction after total hip arthroplasty(THR) and limb equalization after THR in unilateral developmental dysplasia of the hip (DDH) is very important. study designed to measure the difference of adult femoral length between normal and dislocated hip in unilateral DDH.

Method

Sixty patients with unilateral high riding DDH (crow type 3,4) who were underwent THR included. All the cases had digital lower limb scanograms. Exclusion criteria was any previous hip or femur surgery, any rheumatoid disease, history of any disease that affect the growth. All the scanograms measured by one fellowship of adult reconstruction and one radiologist specialized in musculoskeletal imaging. Each one repeated the measurements two months later blindly and inter observer and intra observer reliability checked. Each one measured femoral length in both sides from greater trochanter(GT), to the distal surface of the femoral condyles.

Introduction

In situ pinning for classic slipped capital femoral epiphysis(SLIP) is evolving to a more direct and anatomic realignment of proximal femoral epiphysis; but in no study the result of such a treatment in Valgus Slip, an uncommon type of slipped capital femoral epiphysis, has been reported.

Material and methods

Three hips in three patients (one male, two female) with valgus SCFE were treated by sub-capital realignment (two hips) or femoral neck osteotomy (one hip) for anatomic realignment of proximal femoral epiphysis. Extended retinacular flap technique performed through surgical hip dislocation in all hips. They followed clinically by Merle d'Aubigne Scale and visual analog scale for pain and radiographically for AVN, recurrence of SLIP, chondrolysis and osteoarthritis

Objective

To define the common pathology of the hips with irreducible posterior dislocation combined with femoral head fracture and the outcome of surgical treatment using surgical hip dislocation technique.

Design: retrospective observational clinical study

Setting: Level III referral trauma center

Patients/Participants: from January 2011till February 2014 five patients with irreducible posterior hip dislocation and femoral head fracture who underwent operation were included and they followed for at least 18 months.

Intervention

Open reduction and internal fixation of fractured femoral head and labral repair by suture anchors using surgical hip dislocation through trochanteric flip osteotomy approach.

Main Outcome Measures: Clinical and radiographical findings of the irreducible posterior hip dislocation, intraoperative findings, clinical outcomes using Merle d'Aubigné & Postel and Thompson & Epstein scores, and radiological outcome.

Objectives

Although most joint surgeons have reached a consensus that preoperative risk assessment and appropriate medical intervention for elderly patients of primary total hip arthrplasty (PTHA) could significantly reduce postoperative complications and mortality, there is still lack of a detailed and comprehensive approach for risk stratifying and a systematic method for risk allaying. We aimed to explore the risk factors related to the aggravation of preoperative complications and the appearance of complications post-operation of primary total hip arthrplasty (PTHA) in elderly patients for hip fracture.

Patients and methods

We retrospectively reviewed the demographic and clinical data of 156 patients who underwent PTHA for hip fracture from January 2014 to December 2016, of which there were 61 male (39.1%) and 95 female (60.9%) patients; 111 patients aged 60–79 years (71.2%) and 45 patients ≥ 80 years old (28.8%); 125 patients of femoral neck fracture (80.1%) and 31 patients of inter-trochanteric fracture (19.9%); 109 patients of spinal anesthesia (69.9%) and 48 patients of general anesthesia (30.1%); 85 patients undergoing surgery within 3 days (54.5%) and 71 patients operated ≥ 4 days (45.5%) since admission. We evaluated the correlations among gender, age, type of fracture, methods of anesthesia, time of operation since admission, the aggravation of preoperative complications and the appearance of postoperative complications post PTHA using the IBM SPSS Statistics (version 21) and the Exce1 2016.

Objectives

Tranexamic acid (TXA), an inhibitor of fibrinolysis blocking the lysine-binding site of plasminogen to fibrin, has been reported to reduce intraoperative and postoperative blood loss in patients undergoing primary total hip arthroplasty (PTHA) both with and without cement. Both intravenous (IV) and topical (TOP) administration of TXA can effectively reduce blood loss in THA without increasing risk of deep venous thrombosis (DVT). However, there have been few reports investigating the combination of intravenous and topical administration of TXA in bilateral cementless PTHA. We investigated the effects of combined intravenous and topical administration of TXA on postoperative blood loss, drainage volume, and perioperative complications in patients with bilateral simultaneous cementless PTHA for hip osteoarthritis.

Patients and methods

We retrospectively reviewed the demographic and clinical data of 41 patients who underwent bilateral simultaneous cementless PTHA for hip osteoarthritis from May 2015 to January 2017, of which there were 29 male (70.7%) and 12 female (29.3%) patients. Patients in IV group (n= 11) received only TXA (15 mg/kg) 10 min prior to the incision of each side; and patients in IV + TOP group (n=13) received i.v. TXA (15 mg/kg) combined with topical adiministration (1.0 g) of TXA during the each THA procedure; patients in control group (n=17) received the same dosage of normal saline both i.v. and topically. Outcome measures were total blood loss, hemoglobin, hematocrit value (HCT) changes preoperatively, and on the 1st, 3rd postoperative day, the amount of drainage, and perioperative complications.

Introduction

Total knee arthroplasty (TKA) is an excellent treatment for end-stage osteoarthritis of the knee. In Asian countries, the number of TKA performed has rapidly increased, and is expected to continue so with its 4.4 billion population and increasing life expectancy. Asians' knees are known to be kinematically different to Caucasians after TKA. Controversy exists as to whether multi-radius (MR) or the newer single-radius (SR) TKA has superior outcome. Studies regarding this have been largely based on Caucasian data with few small sample Asian data.

Methods

This is a retrospective analysis of prospectively collected institutional registry data between 2004 and 2015. Outcomes of 133 single-radius (SR) (Scorpio NRG, Stryker) and 363 multi-radius (MR) (Nexgen LPS, Zimmer) primary TKA for primary osteoarthritis were compared. All TKA was performed or directly supervised by the senior author. Range of motion (ROM), Oxford Knee Score (OKS), SF-36 physical component score (SF36-PCS), SF-36 mental component score (SF36-MCS), Knee Society Function Score (KS-FS) and Knee Score (KS-KS) were recorded preoperatively and at 2 years post-operation.

Objectives

The purpose of this observational study was to investigate and analyze the nature of the shared content of lower extremity total joint arthroplasty (TJA) patients on Instagram. Specifically, we evaluated: 1) perspective and timing of the social media posts (pre-, peri-, or post-operative); 2) tone of the post (positive or negative); 3) focus of the post (including activities of daily living (ADLs), rehabilitation, return-to-work (RTW)); and 4) compare these findings between hip and knee arthroplasties.

Methods

A search of the public Instagram domain was performed over a 6 month period. Total hip and knee arthroplasty were selected for the analysis using the following terms: “#totalhipreplacement,” “#totalkneereplacement,” and associated terms. A total of 1,287 individual public posts of human subjects were shared during the period. A categorical scoring system was manually applied for media format (photo or video), time (pre-, peri- or post-operative) period, tone (positive or negative), RTW reference, ADLs reference, rehabilitation reference, surgical site reference, radiograph image, satisfaction and dissatisfaction references. The post perspective was recorded.

INTRODUCTION

Avascular necrosis (AVN) of the femoral head (FH) initiates from biological disruptions in the bone and may progress to mechanical failure of the hip. Mechanical and structural properties of AVN bone have not been widely reported, however such understanding is important when designing therapies for AVN. Brown et al.[1] assessed mechanical properties of different regions of AVN FH bone and reported 52% reduction in yield strength and 72% reduction in elastic modulus of necrotic regions when compared to non-necrotic bone. This study aimed to characterise structural and mechanical properties of FH bone with AVN and understand the relationship between lesion volume and associated mechanical properties.

METHODS

Twenty FH specimens from patients undergoing hip arthroplasty for AVN and six non-pathological cadaveric FH controls were collected. Samples were computed tomography scanned and images analysed for percentage lesion volume with respect to FH volume. Samples were further divided for structural and mechanical testing. The mechanical property group were further processed to remove 9mm cylindrical bone plugs from the load bearing and non-load-bearing regions of the FHs. FH and bone plug samples were tested in compression (1mm/min); elastic modulus and yield stress were calculated.

Background

In recent literatures, medial instability after TKA was reported to deteriorate early postoperative pain relief and have negative effects on functional outcome. Furthermore, lateral laxity of the knee is physiological, necessary for medial pivot knee kinematics, and important for postoperative knee flexion angle after cruciate-retaining total knee arthroplasty (CR-TKA). However, the influences of knee stability and laxity on postoperative patient satisfaction after CR-TKA are not clearly described.

We hypothesized that postoperative knee stability and ligament balance affected patient satisfaction after CR-TKA. In this study, we investigated the effect of early postoperative ligament balance at extension on one-year postoperative patient satisfaction and ambulatory function in CR-TKAs.

Materials & Methods

Sixty patients with varus osteoarthritis (OA) of the knee underwent CR-TKAs were included in this study. The mean age was 73.6 years old. Preoperative average varus deformity (HKA angle) was 12.5 degrees with long leg standing radiographs.

The knee stability and laxity at extension were assessed by stress radiographies; varus-valgus stress X-ray at one-month after operation. We measured joint separation distance (mm) at medial compartment with valgus stress as medial joint opening (MJO), and distance at lateral compartment with varus stress as lateral joint opening (LJO) at knee extension position. To analyze ligament balance; relative lateral laxity comparing to the medial, varus angle was calculated.

New Knee Society Score (NKSS) was used to evaluate the patient satisfaction at one-year after TKA.

We measured basic ambulatory functions using 3m timed up and go test (TUG) at one-year after surgery.

The influences of stability and laxity parameters (MJO, LJO and varus angle at extension) on one-year patient satisfaction and ambulatory function (TUG) was analyzed using single linear regression analysis (p<0.01).

Introduction

Geometric variations of the hip joint can give rise to repeated abnormal contact between the femur and acetabular rim, resulting in cartilage and labrum damage. Population-based geometric parameterisation can facilitate the flexible and automated in silico generation of a range of clinically relevant hip geometries, allowing the position and size of cams to be defined precisely in three dimensions. This is advantageous compared to alpha angles, which are unreliable for stratifying populations by cam type. Alpha angles provide an indication of cam size in a single two-dimensional view, and high alpha angles have been observed in asymptomatic individuals.

Parametric geometries can be developed into finite element models to assess the potential effects of morphological variations in bone on soft tissue strains. The aim of this study was to demonstrate the capabilities of our parameterisation research tool by assessing impingement severity resulting from a range of parametrically varied femoral and acetabular geometries.

Methods

Custom made MATLAB (MathWorks) and Python codes^[1] were used to generate bone surfaces, which were developed into finite element models in Abaqus (SIMULIA). Parametric femoral surfaces were defined by a spherical proximal head and ellipse sections through the neck/cam region. This method produced surfaces that were well fitted to bone geometry segmented from CT scans of cam patients and capable of producing trends in results similar to those found using segmented models. A simplified spherical geometry, including the labrum and acetabular cartilage, represented the acetabulum.

Femoral parameters were adjusted to define relevant variations in cam size and position. Two radii (small and large cams) and two positions (anterior and superior cams) were defined resulting in four models. Alpha angles of these parametric femurs were measured in an anterior-posterior view and a cross-table lateral view using ImageJ (NIH). A further model was developed using a femur with a medium cam size and position, and the level of acetabular coverage and labrum length were varied.

Bones were modelled as rigid bodies and soft tissues were modelled as transversely isotropic linearly elastic materials. With the acetabulum fully constrained in all cases, the femurs were constrained in translation and rotated to simulate flexion followed by internal rotation to cause impingement against the labrum.

INTRODUCTION

Interest in tissue-preserving or minimally invasive total hip arthroplasty (THA) is increasing with focus toward decreased hospital stay, enhanced rehabilitation, and quicker recovery for patients. Two tissue-preserving techniques, the anterior and superior approaches to THA, have excellent clinical results, but little is known about their relative impact on soft tissue. The purpose of this study was to evaluate the type and extent of tissue damage after THA with each approach, focusing on abductors, short external rotators, and the hip capsule.

METHODS

Total hip arthroplasty was performed on bilateral hips of eleven fresh-frozen cadavers (22 hips). They were randomized to anterior THA performed on one side and superior THA performed on the other, in the senior authors' standard technique. Two independent examiners graded the location and extent of tissue injury by performing postsurgical dissections. Muscle bellies, tendons, and capsular attachments were graded as intact, split, damaged (insignificant, minimal, moderate, or extensive damage), or detached based on direct visual inspection of each structure. Tissue injury was analyzed with either a chi-squared (≥5 qualifying structures) or Fisher's exact test (<5 qualifying structures). P values <0.05 were significant.

Aims

Joint arthroplasties may be associated with a blood loss, which necessitates transfusion. Especially, hip arthroplasties are highly associate with transfusion to compensate perioperative bleeding. Orthopaedic surgeons and patients have increasing concerns regarding complications of blood transfusions. Although various methods to reduce transfusions have been attempted in TJA, a high percentage of patients require a transfusion during and after the procedures. The purposes of this study were to evaluate the trends of the transfusion(transfusion rates, transfusion amounts, economic burden) in hip arthroplasties, using nationwide data from the National Health Insurance Service (NHIS).

Patients and methods

We used data from nationwide claims database of Health Insurance Review Assessment Service (HIRA). The data managed by the NHIS were used to identify the 161,934 hip arthroplasties by 3 categories including bipolar hemiarthroplasty(BH), total hip arthroplasty(THA), and revision arthroplasty(RA) from 2007 to 2015. These 3 categories were classified using the operation code recorded in the requisition data of NHIS. The transfusion rates, transfusion amounts, proportion of transfusion, cost of each type of operation was investigated and stratified by age, gender, hospital type, and area in hip arthroplasties. The proportion of transfusion about whole blood, red blood cell, fresh frozen plasma, platelet, was also evaluated in hip arthroplasties.

Introduction & Aims

The traditional method of soft-tissue balancing during TKA is subjective in nature, and stiffness and instability are common indications for revision, suggesting that TKA balancing by subjective assessment is suboptimal. This study examines the intraoperative mediolateral loads measured with a nanosensor-enabled tibial insert trial and the sequential balancing steps used to achieve quantitative balance. Data obtained from a prospective multicenter study was assessed to determine the effect of targeted ligament release on intra-articular loading, and to understand which types of releases are necessary to achieve quantified ligament balance.

Methods

A group of 129 patients received sensor-assisted TKA, as part of a prospective multicenter study. Medial and lateral loading data were collected pre-release, during any sequential releases, and post-release. All data were collected at 10, 45, and 90 degrees during range of motion testing. Ligament release type, release technique type, and resultant loading were collected.

Introduction

Ceramic ball heads are well known in hip arthroplasty for their superior tribology performance and high burst strength. To assess the ball head performance and the in-vivo fracture risk Pandorf et al 2008 examined the burst strength of BIOLOX®forte (pure aluminium oxide ceramic, CeramTec GmbH, Plochingen, Germany) ball heads on clean standard test tapers and contaminated test tapers. They found that fat tissue and scratches are reducing the burst strength to 40% and to 20% of the reference burst strength, respectively. The aim of this work is to investigate if BIOLOX®delta (alumina matrix ceramic, CeramTec GmbH, Plochingen, Germany) ball heads show a similar behaviour as BIOLOX®forte ball heads with respect to taper contamination.

Materials and Methods

Each test series consisted of n=5 BIOLOX®delta 28–12/14 L ball heads and n=5 metal test tapers (Ti-6Al-4V, ISO 5832-3). For the reference series the metal tapers remained untouched representing the CeramTec standard test procedure. For the fluid series the ball heads were filled up with tap water or calf blood serum. For the solid series the metal test tapers were contaminated with small particles of bovine bone, commercially available bone cement and porcine fat tissue in the engagement zone. A chisel and a slight hammer tap were used to scratch the proximal region of the metal test taper. The ball heads were then manually attached to the contaminated metal test tapers without further force appliances. An apparatus according to ISO 7206-10 was used for burst testing. The tests were performed at CeramTec in-house test laboratory.

Introduction

A deep squat (DS) is a challenging motion at the level of the hip joint generating substantial reaction forces (HJRF). As a closed chain exercise, it has great value in rehabilitation and muscle strengthening of hip and knee. During DS, the hip flexion angle approximates the functional range of hip motion risking femoroacetabular impingement in some morphologies. In-vivo HJRF measurements have been limited to instrumented implants in a limited number of older patients performing incomplete squats (< 50° hip flexion and < 80° knee flexion). On the other hand, total hip arthroplasty is being increasingly performed in a younger and higher demanding patient population. These patients clearly have a different kinetical profile with hip and knee flexion ranges going well over 100 degrees. Since measurements of HJRF with instrumented prostheses in healthy subjects would be ethically unfeasible, this study aims to report a personalised numerical solution based on inverse dynamics to calculate realistic in-silico HJRF values during DS.

Material and methods

Thirty-five healthy males (18–25 years old) were prospectively recruited for motion and morphological analysis. DS motion capture (MoCap) acquisitions and MRI scans with gait lab marker positions were obtained. The AnyBody Modelling System (v6.1.1) was used to implement a novel personalisation workflow of the AnyMoCap template model. Bone geometries, semi-automatically segmented from MRI, and corresponding markers were incorporated into the template human model by an automated procedure. A state of-the-art TLEM 2.0 dataset, included in the Anybody Managed Model Repository (v2.0), was used in the template model. The subject-specific MoCap trials were processed to compute kinematics of DS, muscle and joint reaction forces in the entire body. Resulting hip joint loads were compared with in-vivo data from OrthoLoad dataset. Additionally, hip and knee joint angles were computed.

Background

Recent clinical studies have suggested that systemic metal ion levels are significantly elevated at midterm follow-up after ceramic-on-metal (COM) bearing. However, it is not clear whether there is a correlation between patient- and surgical-related factors including the lifestyle and elevated levels of serum metal ions following COM total hip arthroplsty (THA).

Material and Methods

Two hundred and one patients (234 hips) including 121 COM patients (140 hips) and 80 non-COM patients (94 hips) were enrolled in accordance with the inclusion criteria. The patients were divided into three groups based on the type of surgical bearings used. The Harris Hip Score (HHS), University of California, Los Angeles (UCLA) activity scale score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score were measured, and radiographs were obtained for the analysis. Serum metal ion levels of cobalt and chromium were measured using a high-resolution inductively coupled plasma mass spectrometry. Patient- and surgical-related factors were analyzed to determine which group of patients is at a high risk of metal ion-related problems.

Background

Polyethylene wear in both cemented and uncemented total hip arthroplasty (THA) lead to generation of particles with their access to the interface which has been responsible for periprosthetic osteolysis and subsequent loosening of cup and stem. Many studies have been published studying the pattern of polyethylene wear and its relation to the type of implant (cemented/ uncemented cup or ceramic/metal head) used. No study in our knowledge has strictly focused on the effect of cemented versus uncemented stem on the polyethylene wear rates. We tried to compare the polyethylene wear rates reckoned with software (Poly Ware REV 7) of ultra high molecular weight polyethylene (UHMWPE) in hybrid and uncemented THA and its effect on complications of total hip replacements.

Method

We retrospectively reviewed pre-matched 56 patients in uncemented group with 112 patients in hybrid group on the basis of polyethylene wear rate, revision rates and clinical issues, with mean follow up of 9.42 and 7.25 years (yrs.) respectively.