Introduction

Aseptic loosening has been reported to be the most common, contemporary mode of total knee arthroplasty failure. It has been suggested that the etiology of revision due to loosening can be attributed, in part, to joint imbalance and the variability inherent in standard surgical techniques. Due to the high prevalence of revision, the purpose of this study was to quantify the change in kinetic loading of the knee joint before versus after the application of the final cement-component complex.

Methods

Ninety-two consecutive, cruciate-retaining TKAs were performed, between March 2014 and June 2014, by two collaborating surgeons. Two different knee systems were used, each with a different viscosity cement type (either medium viscosity or high viscosity). All knees were initially balanced using a microelectronic tibial insert, which provides real-time feedback of femoral contact points and joint kinetics. After the post-balance loads were captured, and the surgeon was satisfied with joint balance, the final components were cemented into place, and the sensor was re-inserted to capture any change in loading due to cementing technique.

Introduction

Instability after total knee arthroplasty (TKA) represents, in excess of, 7% of reasons for implant failure. This mode of failure is correlated with soft-tissue imbalance, and has continued to be problematic despite advances in implant technology. Thus, understanding the options available to execute safe and effective soft-tissue release is critical to mitigating future complications due to instability. This study aimed to use intraoperative sensors to evaluate a multiple needle puncturing technique (MNPT), in comparison with traditional transection-based release, to determine its biomechanical and clinical efficacy.

Methods

Seventy-five consecutive, cruciate-retaining TKAs were performed, as part of an 8-site multicenter study. All procedures were performed with the use of an intraoperative sensor to ensure quantitative balance, as per previously reported literature. Of the 75-patient cohort, 50 patients were balanced with the MNPT; 20 patients were balanced with traditional transection. All patients were followed out to 1-year, and administered KSS, WOMAC, and satisfaction. Alignment and ROM was captured for all patients, pre-operatively and at the 1-year follow-up interval.

Introduction

The rate of technological innovation in procedural total knee arthroplasty has left little time for critical evaluation of a new technology before the adoption of even newer modalities. With more drastic financial restrictions being placed on operating room spending, orthopaedic surgeons are now required to provide excellent results on a budget.

It is integral that both clinical efficacy and cost-effectiveness of these intraoperative technologies be fully understood in order to provide patients with effectual, economically conscious care. The purpose of this qualitative analysis of literature was to evaluate clinical and economic efficacy of the three most prominent technologies currently used in TKA: computer navigation, patient-specific instrumentation, and kinetic sensors.

Methods

Three hundred and ninety one publications were collected; 100 were included in final qualitative analysis. Criteria for inclusion in the analysis was defined only insofar as that each piece assessed one of the above listed aspects of the three technologies Literature included in the final evaluation contained background information on each respective technology, clinical outcomes, revision rates, and/or cost analyses. All comparisons were conducted in a strictly qualitative manner, and no attempts were made to conduct interstudy statistical analyses due to the high level of variability in methodology and data collected.

Introduction

Posterior glenoid wear is common with glenohumeral osteoarthritis. To correct posterior wear, surgeons may eccentrically ream the anterior glenoid to restore version. However, eccentric reaming undermines prosthesis support by removing unworn anterior glenoid bone, compromises cement fixation by increasing the likelihood of peg perforation, and medializes the joint line which has implications on joint stability. To conserve bone and preserve the joint line when correcting glenoid version, manufacturers have developed posterior augment glenoids for aTSA and rTSA applications. This clinical study quantifies outcomes achieved using posteriorly augmented aTSA/rTSA glenoid implants in patients with severe posterior glenoid wear at 2 years minimum follow-up.

Methods

47 patients (mean age: 68.7yrs) with 2 years minimum follow-up were treated by 5 fellowship trained orthopaedic surgeons using either 8° posteriorly augmented aTSA/rTSA glenoid components in patients with severe posterior glenoid wear. 24 aTSA patients received posteriorly augmented glenoids (65.8 yrs; 7F/17M) for OA and 23 rTSA patients received posteriorly augmented glenoids (71.8 yrs; 9F/14M) for treatment of CTA and OA. Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and external rotation were also measured to quantify function. Average follow-up was 27.5 months (aTSA 29.4; rTSA 25.5). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements.

Introduction

Achieving prosthesis fixation in patients with glenoid defects can be challenging, particularly when the bony defects are large. To that end, this study quantifies the impact of 2 different sizes of large anterior glenoid defects on reverse shoulder glenoid fixation in a composite scapula model using the recently approved ASTM F 2028–14 reverse shoulder glenoid loosening test method.

Methods

This rTSA glenoid loosening test was conducted according to ASTM F 2028–14; we quantified glenoid fixation of a 38mm reverse shoulder (Equinoxe, Exactech, Inc) in composite/dual density scapulae (Pacific Research, Inc) before and after cyclic testing of 750N for 10k cycles. Anterior defects of 8.5mm (31% of glenoid width and 21% of glenoid height; n=7) and 12.5mm (46% of glenoid width and 30% of glenoid height; n=7) were milled into the composite scapula along the S/I glenoid axis with the aid of a custom jig. The baseplate fixation in scapula with anterior glenoid defects was compared to that of scapula without an anterior glenoid defect (n = 7). For the non-defect scapula, initial fixation of the glenoid baseplates were achieved using 4, 4.5×30mm diameter poly-axial locking compression screws. To simulate a worst case condition in each anterior defect scapulae, no 4.5×30mm compression screw were used anteriorly, instead fixation was achieved with only 3 screws (one superior, one inferior, and one posterior). A one-tailed unpaired student's t-test (p < 0.05) compared prosthesis displacements relative to each scapula (anterior defect vs no-anterior defect).

Introduction

Recent advances in 3D printing enable the use of custom patient-specific instruments to place drill guides and cutting slots for knee replacement surgery. However, such techniques limit the ability to intra-operatively adjust an implant plan based on soft-tissue tension and/or joint pathology observed in the operating room, e.g. cruciate ligament integrity. It is hypothesized that given the opportunity, a skilled surgeon will make intra-operative adjustments based on intra-operative information not captured by the hard tissue anatomy reconstructed from a pre-operative CT scan or standing x-ray. For example, tibiofemoral implant gaps measured intra-operatively are an indication of soft-tissue tension in the patient's knee, and may influence a surgeon to adjust implant position, orientation or size. This study investigates the frequency and magnitude of intra-operative adjustments from a single orthopedic surgeon during 38 unicondylar knee arthroplasty (UKA) cases.

Methods

For each patient, a pre-operative plan was created based on the bony anatomy reconstructed from the pre-operative CT. This plan is analogous to a plan created with patient-specific cutting blocks or customized implants. With robotic technology that utilizes pre-operative imaging, intra-operative navigation and robotic execution, this “anatomic” plan can be fine-tuned and adjusted based on the soft tissue envelop measured intra-operatively. The relative positions of the femur and the tibia are measured intra-operatively under a valgus load (for medial UKA, varus load for lateral UKA) for each patient from extension to deep knee flexion and used to compute the predicted space between the implants (gaps) throughout flexion. The planned position, orientation and size of the components can then be adjusted to achieve an optimal dynamic ligament balance prior to any bony cuts. This is the plan that is then executed under robotic guidance. Intra-operative adjustments are defined as any size, position or orientation changes occurring intra-operatively to the pre-operative anatomic plan.

Introduction

A better understanding of the rate of improvement associated with aTSA and rTSA is critical to establish accurate patient expectations for treatment to reduce pain and restore function; more realistic patient expectations pre-operatively may lead to greater patient satisfaction post-operatively. To this end, this study quantifies the rate of improvement in outcomes of aTSA and rTSA using 5 different scoring metrics for 1641 patients with one platform shoulder arthroplasty system.

Methods

1641 patients (mean age: 69.3yrs) were treated by 14 orthopaedic surgeons using one platform shoulder system (Exactech, Inc). 729 patients received aTSA (65.3yrs; 384F/345M) for treatment of degenerative arthritis and 912 patients received rTSA (72.5yrs; 593F/319M) for treatment of CTA/RCT/OA. Each patient was scored pre-operatively and at various follow-up intervals (3 months, 6months, annually, etc) using the SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, active forward flexion, and active/passive external rotation were also measured. 4439 total follow-up reports were analyzed (1851 and 2588 rTSA). Improvements in outcome using each metric score were calculated and normalized on a 100 point scale. The rate of improvement was analyzed using a 40 point moving filter treadline and with a 3rd order polynomial treadline over the entire range of follow-up.

Introduction

The clinical impact of scapular notching is controversial. Some reports suggest it has no impact while others have demonstrated it does negatively impact clinical outcomes. The goal of this clinical study is to analyze the pre- and post-operative outcomes of 415 patients who received rTSA with one specific prosthesis (Equinoxe; Exactech, Inc).

Methods

415 patients (mean age: 72.2yrs) with 2 years minimum follow-up were treated with rTSA for CTA, RCT, and OA by 8 fellowship trained orthopaedic surgeons. 363 patients were deemed to not have a scapular notch by the implanting surgeon at latest follow-up (72.1 yrs; 221F/131M) whereas 52 patients were deemed to have a scapular notch at latest follow-up (73.3 yrs; 33F/19M). Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and internal/external rotation were also measured to quantify function. Average follow-up was 38.1 months (No Notch: 37.2; Notch: 44.4). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements.

Introduction

Due to the predictability of outcomes achieved with reverse shoulder arthroplasty (rTSA), rTSA is increasingly being used in patients where glenoid fixation is compromised due to presence of glenoid wear. There are various methods to achieve glenoid fixation in patients with glenoid wear, including the use of bone grafting behind the glenoid baseplate or the use of augmented glenoid baseplates. This clinical study quantifies clinical outcomes achieved using both techniques in patients with severe glenoid wear at 2 years minimum follow-up.

Methods

80 patients (mean age: 71.6yrs) with 2 years minimum follow-up were treated by 7 fellowship trained orthopaedic surgeons using rTSA with bone graft behind the baseplate or rTSA with an augmented glenoid baseplate in patients with severe posterior glenoid wear. 39 rTSA patients (14 female, avg: 73.1 yrs; 25 male, avg: 71.5 yrs) received an augmented glenoid (cohort composed of 24 patients with an 8° posterior augment baseplate and 15 patients with a 10° superior augment baseplate) for treatment of CTA, RCT, and OA with a medially eroded scapula. 41 rTSA patients (27 female, avg: 73.0 yrs; 14 male, avg: 66.9 yrs) received glenoid bone graft (cohort composed of 5 patients with allograft and 36 patients with autograft) for treatment of CTA, RCT, and OA with a medially eroded scapula. Outcomes were scored using SST, UCLA, ASES, Constant, and SPADI metrics; active abduction, forward flexion, and internal/external rotation were also measured to quantify function. Average follow-up was 31.2 months (augment 28.3; graft 34.1). A two-tailed, unpaired t-test identified differences (p<0.05) in pre-operative, post-operative, and pre-to-post improvements.

Introduction

Total joint arthroplasty is frequently necessary when a traumatic or degenerative disease leads to develop osteoarthritis (OA). Nowadays, the main reason for long term prosthesis failure is due to osteolysys and aseptic loosening of the implant itself, that are related to UHMWPE wear debris [1–3]. Different solutions to overcome this issue have been proposed, including different couplings like metal-on-metal and ceramic-on-ceramic. Our hypothesis was that a hard ceramic thin film realized on the plastic component (i.e. UHMWPE) could improve the friction and wear performance in a prosthetic coupling. The purpose of the presented study was therefore to characterize from the point of view of structure and mechanical performance of this ceramic-coated plastic component. The thin films were specifically realized by means of the novel Pulsed Plasma Deposition (PPD) technique [4].

Materials and methods

PPD technique was used to deposit Yttria-stabilized zirconia (YSZ at 3%) films on medical-grade UHMWPE substrates [4]. The morphology and micro-structure were characterized by Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). By means of nanoindentation and scratch tests mechanical properties were investigated. Ball-on-disk tribological tests were carried out in air, deionized water and physiological solution against alumina balls (6 mm diameter, grade 200) used as counterpart; friction evaluation of the proposed approach and the corresponding worn track were analyzed by SEM-EDS.

Introduction

Protective hard coatings are appealing for several technological applications and even for orthopaedic implants and prosthetic devices. For what concerns the application to prosthetic components, coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1, 2]; at the same time, concerning use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) ceramic material has shown high strength, fracture toughness, elasticity, hardness, and wear resistance [3, 4]. The purpose of this study was to directly deposit ZTA coatings by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [5]. Preliminary characterization of realized coatings from the point of view of morphology, wettability, adhesion and friction coefficients was performed.

Materials and methods

PPD technique was used to deposit ZTA coatings; this technique is able to maintain the stoichiometry of the starting target. In this study we started from a cylindrical ZTA target (30 mm diameter × 5 mm thickness, 75% alumina / 25% zirconia) and followed the procedure described by Bianchi et al [5]. Characterization of morphology, micro-structure and chemistry of deposited coatings was performed by Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) and Atomic Force Microscope (AFM). Coating-substrate interface quality were investigated by micro-scratch tests. Measurement of the contact angle between a drop of 1 ml of ultrapure water and the surface of the sample was performed to estimate the degree of wetting. A ZTA-coated stainless steel ball (AISI 420, 3 mm radius) was coupled against medical grade UHMWPE to evaluate the friction of the proposed coupling in preliminary ball-on-disk tribological tests.

Background

A challenge to obtaining proper glenoid placement in total shoulder arthroplasty is eccentric posterior bone loss and associated glenoid retroversion. This bone loss can lead to poor stability and perforation of the glenoid during arthroplasty. The purpose of this study was to evaluate the three dimensional morphology of the glenoid with associated bone loss for a spectrum of osteoarthritis patients using 3-D computed tomography imaging and simulation software.

Methods

This study included 29 patients with advanced glenohumeral osteoarthritis treated with shoulder arthroplasty. Three-dimensional (3D) reconstruction of preoperative CT images was performed using image analysis software. Glenoid bone loss was measured at ten, vertically equidistant axial planes along the glenoid surface at four distinct anterior-posterior points on each plane for a total of 40 measurements per glenoid. The glenoid images were also fitted with a modeled pegged glenoid implant to predict glenoid perforation.

Introduction

Reverse Shoulder Arthroplasty (RSA) improves the mechanics of rotator cuff deficient shoulders. To optimize functional outcomes and minimize failures of the RSA manufacturers have recently made innovative design modifications with lateralized components. However, these innovations have their own set of biomechanical trade-offs, such as increased shear forces along the glenoid bone interface. The objective of this study was to develop an efficient musculoskeletal model to evaluate and compare both the muscle forces and joint reactive force of a normal shoulder to those implanted with varied RSA implant designs. We believe these findings will provide valuable insight into possible advantages or shortcomings of this new RSA design.

Methods

A kinematic model of a normal shoulder joint was adapted from publically available musculoskeletal modeling software. Static optimizations then allowed for calculation of the individual muscle forces, moment arms and joint reactive forces relative to net joint moments. An accurate 3D computer models of humeral lateralized design (HLD) (Equinoxe, Exactech, Gainesville FL, USA), glenoid lateral design (GLD) (Encore, DJO Global, Vista CA, USA), and Grammont design (GD) (Aequalis, Tornier, Amsterdam, NV) reverse shoulder prostheses was also developed and parametric studies were performed based on the numerical simulation platform.

Introduction

Most Japanese patients who receive total hip arthroplasty (THA) are osteoarthritic and 70% have development dysplasia of the hip. Their stature is shorter than average and their sizes (acetabular cup and femoral stem) are smaller. The Taperloc Microplasty (BIOMET) is a short femoral stem. It was launched on July 2012 in Japan (extended on January 2013). It is essentially a shortened version of the Taperloc stem (35mm shorter than the standard stem).

Objectives

We aimed to evaluate the outcomes of minimally invasive anterolateral THA using a short stem.

Introduction

In recent years, an increasing number of reports related to adverse reactions to metal debris (ARMD) following metal-on-metal (MOM) total hip arthroplasty (THA) have been published. Some patients who experience ARMD require revision surgery.

Objectives

In this study, we aimed to evaluate the mid-term results of MOM THA.

Methods

We prospectively investigated 51 patients who underwent primary TKA at the hospital from July 2013 to December 2013. All were of Japanese ethnicity. The mean age at the surgery was 74.9 years and average BMI was 26.0. There were 45 (88.2%) cases of osteoarthritis and 5 (9.8%) of rheumatoid arthritis. A single knee surgery team performed all operations with cemented type prostheses by utilizing pneumatic tourniquet. There were 21 cases of one-staged bilateral TKA and 30 of unilateral TKA. All patients were applied intermittent pneumatic compression (IPC) until 24 hours and graduated compression stockings for 3[高木1] weeks after the operation. Beginning from the day after the surgery, the patients were allowed walking with walker, along with the gradual range of motion exercise for physical thromboprophylaxis. Low-dose unfractionated heparin (LDUH) as a chemical thromboprophylaxis was administered subcutaneously for 3 days after the surgery. Informed consent was obtained regarding this thromboprophylaxis protocol. CE-CT and venous US were performed at the 4th day after surgery and images were read by a single senior radiologist team. The patients without DVT/PE by examination, they did not take additional chemical thromboprophylaxis. In cases of existence of DVT, continuous heparin administration and oral warfarin were applied and adjusted in appropriate dose for treatment. Warfarin was continued to be applied for at least three months until the patients had no symptoms and normal D-dimer level. In cases of PE, additional ultrasonic echocardiography (UCG) was performed, and then we consulted cardiologist to treat for PE.

Results

CE-CT was performed in 42 patients (82.3%), otherwise nine patients (17.7%) could not take the examination because of exclusion criteria. There was no side-effect regard to contrast medium. The incidence of DVT and/or PE was 32 patients (62.7%), including two PE (3.9%), 21 DVT (41.1%) and nine both PE and DVT (17.6%). Six-teen patients were used LDUH routinely for 3 days after surgery. Five patients were used continuous heparin administration and oral warfarin instead of using LDUH because of medical co-morbidities. Additional continuous heparin administration and oral warfarin after LDUH use was needed in 26 patients. Three patients who had duodenal ulcer with chronic pancreatitis, massive PE with right heart strain and multiple DVT/PE with HIT antibody were needed another treatment.

INTRODUCTION

Soft-tissue balancing of the knee is fundamental to the success of total knee arthroplasty(TKA). Preparing rectangular extension and flexion joint gaps in the most important goal in TKA, because it facilitates functional stability of the knee. In gap balancing technique, we decided the femoral component rotation according to the ligament balance in flexion. Component and limb alignment are important considerations during TKA. Three-dimensional positioning of TKA implants and exact mechanical axis has an effect on implant loosening, polyethylene stresses, and gait. According to the recent reports, the navigation system made it possible to achieve aligned implants more than conventional TKA. Hybrid Navigation technique which is our procedure is combination of navigation system and modified gap technique. In other words, exact mechanical axis is gained by navigation system, stable stability of knee joint is gained by modified gap technique.

PURPOSE

The purpose of this study is to carry out clinical evaluation and image assenssment using computed tomography (CT) of the patients who underwent hybrid navigation technique TKA.

INTRODUCTION

Important surgical requirements for optimal function are accurate bone cut alignments and soft tissue balancing. From an unbalanced state, balancing can be achieved by Surgical Corrections including soft tissue releases, bone cut modifications, and changing tibial insert thickness. Surgical balancing can now be quantified using an instrumented tibial trial, but the procedures and results need further investigation. Our major purpose was to determine the initial balancing after making the bone cuts, and the final accuracy of balancing after Surgical Corrections. A related purpose was to determine the number and effectiveness of different Corrections in achieving balancing.

METHODS

During 101 surgeries of a PCL-retaining TKA, screen capture software recorded the video feed of surgery, angular data from the navigation system, and lateral and medial contact forces from the instrumented tibial trial. Initial bone cuts were made using navigation based on measured resection. The instrumented tibial trial measured the magnitudes and locations of the contact forces on the lateral and medial sides throughout flexion. The Heel Push Test (Walker 2014) determined the initial balancing, defined as a ratio of the medial/total force at 0, 30, 60 and 90 degrees flexion. A balanced knee with equal lateral and medial forces would show a value of 0.5. Surgical Corrections were then performed with the goal of achieving balancing. The most common Corrections were soft tissue releases (total 63 incidences), including MCL, postero-lateral corner, postero-medial corner; and increasing/decreasing tibial insert thicknesses (34 incidences).

Introduction

Clinically relevant attributes of an orthopedic bearing material include its strength, oxidative stability, and wear resistance. Recent reductions in bearing wear and oxidation have been realized by crosslinking (HXLPE), and through the incorporation of α-tocopherol (VE). VE infusion has improved the oxidative stability of HXLPE in vitro [1] and in vivo (as evidenced by retrievals) [2]. However, concern has been raised that adding VE may increase the frictional torque of bearings, potentially increasing the risk of trunnionosis [3]. This study compares the 3D frictional torques of HXLPE vs Vitamin-E HXPLE, against 28 mm and 36 mm metal and ceramic heads.

Methods

Samples were made from prints for commercially available Ringloc liners (Biomet, IN). The HXLPE group was made from ArCom XL, and the VE-HXLPE was made from E1 HXLPE (Biomet, IN). Femoral heads were of cobalt chrome (ASTM F1537), or ceramic (Biolox Delta™). Testing was performed at EndoLab®, Germany. An ISO 14242–1 compliant six-station simulator and 3D gait cycle was utilized. During the cycle, the abduction/adduction range was −4°/+7°, the flexion/extension was +25°/-18°, and the external/internal rotation was −10°/+2°. Testing was performed at 37±2 °C, at 1 Hz, and with a maximum dynamic load of 3.0 kN. Lubrication medium was calf serum, EDTA, and antibiotics diluted in DI water (30 g/l of protein). Measurements were averaged across 5 cycles after 120 completed cycles of motion, and after 200 cycles. Analysis was performed using Minitab with multiple 2-way ANOVAs, with a p=0.05 significance threshold.

Introduction

Achieving proper ligament tension in knee flexion within posterior cruciate retaining (CR) total knee arthroplasty (TKA) has long been associated with clinical success. Ligament balance has been achieved through specific surgical technique steps. No prior study evaluated the possible effects of varying levels of posterior cruciate ligament (PCL) release on femorotibial contact location and PCL ligament strain. The purpose of this computational analysis was to determine what effect-varying levels of PCL release may have on the tibiofemoral kinematics and PCL strain.

Methods

A computational analysis was performed utilizing a musculoskeletal modeling system with ligaments modeled as non-linear elastic structures and ligament insertions. A single CR knee system with two different tibial insert designs was tested, a Guided Motion (GM) and an ultra-congruent, Deep Dished (DD) design. Varying levels of PCL release were simulated by setting the stiffness of both bundles of the PCL to a percentage, ranging from 0–100% in 25% increments. Tibiofemoral kinematics was evaluated by measuring the contact points estimated from the femoral condyle low points, and ligament strain of the anterior-lateral (AL) and posterior-medial (PM) bundles. The maximum PCL strain was determined for each bundle to evaluate the risk of PCL rupture based on the PCL failure strain.

Introduction

Achieving proper ligament tension in knee flexion within cruciate retaining (CR) total knee arthroplasty (TKA) has long been associated with clinical success. The distal femoral joint line (DFJL) is routinely used as a variable to assist in achieving proper flexion-extension gap balancing. No prior study has observed the possible effects of properly restoring the DFJL may have on ligament tension in flexion. The purpose of this computational analysis was to determine what effect the DFJL may have on ligament strains and tibiofemoral kinematics of CR knee designs in flexion.

Methods

A computational analysis was performed utilizing a musculoskeletal modeling system with ligaments modeled as non-linear elastic. Tibiofemoral kinematics, contact points estimated from the femoral condyle low points, and ligament strain, change in length relative to the unloaded length, were measured at 90° knee flexion during a deep knee bend activity. Two different knee implants, a High Flexion CR (HFCR) and a Guided Motion CR (GMCR) design were used. Simulations were completed for changes in superior-inferior (SI) positioning of the femoral implant relative to the femur bone, in 2mm increments to simulate over and under resection of the DFJL.

Introduction

Knee joint should be aligned for reconstruction of the function in Total Knee Replacement(TKR). Although a surgeon try to correct the alignment of a knee joint, sometimes varus/valgus alignment has been tried in order to reconstruct function of knee joint. As a result, the varus or valgus alignment affects to ligaments and soft tissue, and the contact condition is changed between femoral component and tibial insert. One of important factor, wear characteristics of an implant can be changed due to the contact condition. In this study, we performed static contact tests from extension to flexion in varus and valgus to define the effect to contact condition when the alignment is varus or valgus.

Methods

LOSPA TKR femoral component #6 and Tibial insert #5 manufactured by Corentec Co., Ltd. were used as test specimens. The tests have performed with adapting ASTM F2777–10 ‘Standard Test Method for Evaluating Knee Bearing (Tibial Insert) Endurance and Deformation under High Flexion’. The test set like as Fig. 1. The load is applied at 7:3 ratio of lateral-medial by adapting gait analysis. The 5° of jig is used to compare the result in neutral, varus and valgus. The fuji films were used in tests were scanned, and the results were analyzed the compressed area and contact stress as angles of flexion in neutral stance and varus/valgus from scanning. The tests were performed 5 times per each for a reliability.

Introduction

Dislocation is one of the leading causes of revision after primary total hip arthroplasty (THA). Polyethylene wear is one of the risk factors for late dislocations (>2 years). It can induce an inflammatory response resulting in distension and thinning of the pseudocapsule, predisposing the hip to dislocation. Alternatively, eccentric seating of the femoral head in a worn out socket may result in an asymmetric excursion arc predisposing the hip to impingement, levering out and dislocation. Highly cross linked polyethylene has a significantly lower wear rate as compared to conventional polyethylene. Incidence of late dislocations has been shown to be significantly greater with conventional polyethylene bearings as compared to ceramic bearings. However, there is no literature comparing the risk of dislocation between ceramic- on- ceramic (CoC) bearings with metal/ceramic- on- cross linked polyethylene (M/CoP) bearings and this was the aim our study

Methods

Data regarding revision for dislocation after primary THA for osteoarthritis (OA) between September 1999 and December 2013 was obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOA NJRR). Revision risk for dislocation was compared between CoC, CoP, and MoP bearings. Only those THAs with 28 mm, 32 mm, or 36 mm heads were included in the study.

Objective

To investigate the biomechanical mechanism and report preliminary clinical efficacy of eccentric rotational acetabular osteotomy (ERAO) when conduct treatment for developmental dysplasia of the hip (DDH).

Methods

Biomechanical model of the hip joint was established on six female cadaveric hips embalmed by formalin and stimulate ERAO was then performed on the model. Vertical force was loaded on the cadaveric spine from 0 N to 500 N and strain value on femoral head was measured preoperatively and postoperatively when loading force on spine reached the point of 100, 200, 300, 400 and 500 N. Stress value were then calculated base on the measurements. Besides, we reported postoperative follow up cases which were underwent ERAO to treat DDH in our hospital from July 2007 to October 2014. A total of 25 patients (26 hips) were reported, including 6 males and 19 females. Age varies from 11 to 57 years old, and the average age was 31 years old. Postoperative hip function was evaluated by Harris hip score and anteroposterior X⁃ray of pelvic was taken preoperatively and postoperatively to measure the Acetabular⁃head index (AHI), CE angle and Sharp angle.

Introduction

The pathogenesis of primary knee osteoarthritis is due to excess mechanical loading of the articular cartilage. Previous studies have assessed the impact of muscle forces on tibiofemoral kinematics and force distribution. A cadaveric study was performed to evaluate the effect of altering the moment arm of the iliotibial band (ITB) on knee biomechanics.

Method

A robotic system consisting of a 6-DOF manipulator capable of measuring forces on the medial and lateral condyle of a cadaveric knee at various flexion angles and muscle forces was utilized [1]. The system measured the compartment forces at flexion angles between 0° and 30° under 3 simulated loading conditions (300N quadriceps, 100N hamstrings and: i. 0N ITB; ii. 50N ITB; iii. 100N ITB).

Eight fresh frozen human cadaver knee specimens (4 males, 4 females); age range 36 – 50 years; weight range 49 – 90 kg; height range 154 – 190 cm were used in the study.

The ITB and associated lateral soft tissue structures were laterally displaced from the lateral femoral condyle by fixing a metal implant (like in Figure 1) to the distal lateral femur. Mechanical loads on the medial and lateral compartments (with and without the implant) were measured using piezoelectric pressure sensors.

Purpose

It is generally accepted that the cement mantle surrounding the femoral component of a cemented total hip arthroplasty (THA) should be complete without any defects, and of at least 2 mm in thickness. Radiographic evaluation is the basis for assessment of the cement mantle. The adequacy of radiographic interpretation is subject to debate. Poor interobserver and intraobserver reproducibility of radiographic cement mantle assessment has been reported. In this study, 3D template software was used that allow anatomical measurements and analysis of three-dimensional digital femura geometry based on CT scans. The purpose of this study is to analyze the three-dimensional cement mantle thickness of cemented hip stem.

Materials and Methods

52 hips that underwent THA with Exeter stem (Stryker Orthopaedics, Mahwah, NJ) were enrolled in this study. All surgeries were performed by a single surgeon. There were 49 hips in 49 women and 3 hips in 3 men. The average age at surgery was 73 years (range, 60–88 years). The etiology of the hip lesions were osteoarthrosis in 49, rheumatoid arthritis in 3, and osteonecrosis of the femoral head in 1.

For preoperative and postoperative evaluation, a CT scan of the pelvis and knee joint was obtained and was transferred to 3D template software (Zed hip, Lexi, Tokyo, Japan). We evaluated the alignment for stem anteversion/valgus/anterior tilt angles and the contact of the cortical bone with the cement mantle was evaluated.

Background

Cementless short stems have the advantages of easy insertion, reduced thigh pain and being suitable for minimally-invasive surgery, therefore cementless short stem implants have been becoming more widely used. The revelation microMAX stem is a cementless short stem with a lateral flare design that allows for proximal physiological load transmission and more stable initial fixation. Images acquired with T-smart tomosynthesis using a new image reconstruction algorithm offer reduced artifacts near metal objects and clearer visualization of peri-implant trabeculae. Therefore, these images are useful for confirming implant fixation status after total hip arthroplasty (THA). We believe that T-smart tomosynthesis is useful for estimating the condition of microMAX stem fixation and will hereby report on observation of the postoperative course of microMAX stem.

Materials and Methods

Subjects comprised 19 patients (20 hips) who underwent THA using micro MAXstem between July 2012 and November 2014 (males: 7, females: 12, mean age: 67 years, ranging from 38 to 83 years). Four patients had femoral head necrosis and 15 patients had osteoarthritis of the hip. All patients continuously underwent anterior-posterior and lateral view X-ray examination and an anterior-posterior T-smart tomosynthesis scan after the operations.

OBJECTIVE OF THE STUDY

The objective of this study is to establish the medium-term clinical and radiological results with the cementless three-dimensional Vektor-Titan stem compared with conventional cementless stem, such as PerFix stem. The latter stem has a double-wedge design with a rounded distal portion for canal filling (Fig. 1).

MATERIALS AND METHODS

From July, 2004, to May, 2010, fifty seven Vektor-Titan stems and 150 PerFix stems were implanted for the patients with osteoarthritis, avascular necrosis, femoral neck fracture, and rheumatoid arthritis in our hospital. The results were evaluated clinically using Japanese Orthopedic Association (JOA) scores and the Merle d’Aubigne and Postel (M&P) scores. Radiographs were analyzed retrospectively. The criteria used for determining loosening were migration or a total radiolucent zone between the prosthesis/bone cement and host bone, wherein the width increased progressively or change of position, i.e., migration or subsidence of the prosthesis. Migration of the socket seen on the radiograph was defined as either the presence of a ≥2-mm position change or rotation. Position changes of the stem seen on the radiograph were defined as the presence of a progressive subsidence of ≥2 mm or change of position, e.g., varus or valgus. The follow-up period was 9.2 ± 2.6 (range, 5.0–14.0) years.

Introduction

When total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) was indicated for the patient, it is important to perform the exact preoperative planning. Conventionally we created the plan based on the Xp films and transparent acetate sheets. Recntly, the digital radiographs and templating systems were introduced in hospitals and utilized for the preoperative planning. The purpose of this study is to investigate the accuracy of the digital templating by comparing the size of the implants between those chosen by the planning and those actually selected during the operation.

Materials and methods

We investigated the plans of 715 knees with TKAs and 238 knees with UKAs between 2010 and 2014. There were 89 men and 438 women with average age of 72.1. There were 867 osteoarthritis, 46 rheumatoid arthritis, 39 osteonecrosis and 1 revision TKA. We created the preoperative planning using Electronic Picture and Communication system (PACS) and templating system (Advanced Case Plan 2.2 / Stryker). [Fig. 1] During the operation we have checked the actual femoral and tibial sizes of the implants, and compared them with preoperative plannings.

Introduction

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.

Materials and Methods

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

The purpose of this study was to identify the factors contributing to the development and progression of periacetabular osteolytic lesions and to identify which of these lesions can progress at an early stage following THA using repeated computed tomography scans. We also evaluated the accuracy of radiographs in assessing periacetabular osteolysis after THA with uncemented acetabular components and compared it with results of CT analysis.

Methods

CT scans were done in ninety-seven patients (118 hips) who had undergone primary THA between 1996 and 2004 at our hospital at a minimum of two-years postoperatively, from April to August 2006. All the CT images were acquired using high resolution multi-detector row CT (MDCT). The mean age of the patients at the time of surgery was 46.2 years (range, 21–65 years). The mean follow-up at the time of obtaining CT scan was 82.1 months (range, 18–234 months). The second CT scans were obtained in sixty three hips of 49 patients (36 males and 13 females) in 2009. The mean of patient's age was 52.7 years (range, 30 to 76 years). At the time of initial CT scan, the mean duration of implantation was 76.9 months (range, 17–156 months). The volume of periacetabular osteolysis was measured using Rapidia 3D software version. Linear wear of the PE was measured in digitalized radiographs obtained within 3 months of the surgery.

Background

The aim of the study was to analyze effectiveness and safety of packing the medullary canal of the tibia and femur with Herafill (Heraeus Medical GmbH, Wehrheim, Germany), a void filler and antibiotic carrier, during second stage revision total knee arthroplasty(TKA) for periprosthetic joint infection (PJI). We used hybrid cementation technique for the fixation of TKA components with antibiotic-loaded bone cement for femoral and tibial component and cementless stem extensions.

Methods

Two groups of 27 consecutive patients each were matched for gender and age. The study group received Herafill, while the control group did not. Otherwise, the treatment protocol remained the same for both groups. The average follow-up was 48 months (minimum of 34 months).

Introduction

To reduce several disadvantages many surgeons are not using tourniquet in TKA. Here we compared functional outcome along with pain and blood loss in sixty patients.

Material and Method

60 patients who underwent TKA wererandomized into a tourniquet group (n2 = 30) and a non-tourniquet group (n1 = 30). All operations were performed by the samesurgeon and follow-up was for 6 month. Primary outcomes werefunctional and clinical outcomes, as evaluated by KSS and postoperative pain. Secondary outcomes were blood loss, surgical time and visibility, extensor lag and Knee ROM, DVT and radiolucency.

Introduction

Total ankle replacements (TAR) are a much debated alternative to ankle fusion for treatment of end stage arthritis. Compared with hip and knee replacements these are implanted in small numbers with less than 500 per year recorded by the joint registry for England and Wales. The small numbers are a likely result of typically low mid-term survival rates, as well as extensive contra-indications for surgery. There have been multiple generations of TARs consisting of both constrained and unconstrained designs but due to device classification pre-clinical testing has been minimal.

Method

Five Zenith (Corin Group PLC), Titanium Nitride (TiN) coated, unconstrained TARs with conventional polyethylene inserts (Figure 1) were tested in an adapted knee simulator (Simulator Solutions, UK) for six million cycles (MC). The input parameters (Figure 2) were taken from available literature as there is no recognised ISO standard in place. A parametric study with three conditions was conducted to understand the impact of kinematic inputs on the polyethylene wear rate. These conditions aimed to understand the effect of both linear wear with isolated flexion, then multidirectional motion by implementing a rotational input with and without anterior/posterior (AP) displacement. Each condition was run for two MC.

Stage One: Flexion and Load

Stage Two: Flexion, Load, Rotation and Displacement

Stage Three: Flexion, Load and Displacement

A lubricant of 25% bovine serum, 0.03% Sodium Azide solution was used to replicate the protein content of the natural joint capsule. The wear was measured gravimetrically every million cycles and surface measurements taken with a contacting profilometer.

Introduction

Total hip arthroplasty (THA) for a highly dislocated hip can be problematic and technically challenging. Our previous study on cemented THA with subtrochanteric femoral shortening osteotomy revealed a high incidence (20%) of non-union. Therefore, in 2008, we introduced reverse hybrid THA using S-ROM stem for the treatment of a highly dislocated hip. The purpose of this study was to assess the short-term clinical outcomes of this new method.

Patients and methods

Between 2008 and 2014, 13 consecutive reverse hybrid THAs were performed on nine female patients with highly dislocated hips. The average age at the time of operation was 66 years (range, 55–85 years). The acetabular component was fixed in the true acetabulum with bone cement. Transverse osteotomy was performed below the lesser trochanter to shorten the femur and to prevent over-lengthening. The proximal sleeve of the S-ROM stem was then fixed within the proximal fragment, and the distal fin provided rotational stability of the distal fragment. Thus, the two fragments were fixed to each other with the S-ROM stem, and the resected segment was longitudinally cut for grafting at the junction. The postoperative follow-up period was an average of 4 years (range, 1–7 years), and no patients were lost. Preoperative and final Japanese Orthopaedic Association (JOA) hip score, operation time, bleeding amount, intraoperative and postoperative complications, bone healing at the osteotomy site, implant loosening, and revision surgery were retrospectively investigated.

Introduction

Survival rates of recent total ankle replacement (TAR) designs are lower than those of other arthroplasty prostheses. Loosening is the primary indication for TAR revisions [NJR, 2014], leading to a complex arthrodesis often involving both the talocrural and subtalar joints. Loosening is often attributed to early implant micromotion, which impedes osseointegration at the bone-implant interface, thereby hampering fixation [Soballe, 1993]. Micromotion of TAR prostheses has been assessed to evaluate the stability of the bone-implant interface by means of biomechanical testing [McInnes et al., 2014]. The aim of this study was to utilise computational modelling to complement the existing data by providing a detailed model of micromotion at the bone-implant interface for a range of popular implant designs, and investigate the effects of implant misalignment during surgery.

Methods

The geometry of the tibial and talar components of three TAR designs widely used in Europe (BOX®, Mobility® and SALTO®; NJR, 2014) was reverse-engineered, and models of the tibia and talus were generated from CT data. Virtual implantations were performed and verified by a surgeon specialised in ankle surgery. In addition to the aligned case, misalignment was simulated by positioning the talar components in 5° of dorsi- or plantar-flexion, and the tibial components in ± 5° and 10° varus/valgus and 5° and 10° dorsiflexion; tibial dorsiflexed misalignement was combined with 5° posterior gap to simulate this misalignment case. Finite element models were then developed to explore bone-implant micromotion and loads occurring in the bone in the implant vicinity.

Introduction

Patellar resurfacing is performed in more than 90% of primary total knee arthroplasties (TKAs) in the United States, yet far fewer patellae are resurfaced internationally. Multiple randomized controlled trials have shown decreased revision rates in patients with resurfaced patellas (RP) vs. non-resurfaced (NR). However, most of these studies showed no difference in patient satisfaction, anterior knee pain, or knee society scores. (Figure 1) Given uncertain benefits, the purpose of this study was to determine if the rates of patellar resurfacing have changed over the past 10 years worldwide.

Methods

Data was obtained via direct correspondence with registry administrators or abstracted from the annual reports of six national joint registries: Australia, Denmark, England, New Zealand, Norway, and Sweden. Rates of patellar resurfacing between 2003 and 2013 were collected. Where data was available, subgroup analysis was performed to examine revision rates among RP and NR TKAs.

Introduction

The original Charnley-type negative pressure body exhaust suit reduced infection rates in randomized trials of total joint arthroplasty decades ago. Modern positive pressure surgical helmet systems (SHS) have not shown similar benefit, and several recent studies have shown a trend towards increased wound contamination and infection with SHS use. The gown glove interface may be one source of particle contamination.

Objectives

The purpose of this study was to compare particle contamination at the gown glove interface in several modern SHS vs. a conventional gown.

Introduction

The posterior condylar axis of the distal femur is the common reference used to describe femoral anteversion. In the context of Total Hip Arthroplasty (THA), this reference can be used to define the native femoral anteversion, as well as the anteversion of the stem. However, these measurements are fixed to a femoral reference. The authors propose that the functional position of the proximal femur must be considered, as well as the functional relationship between stem and cup (combined anteversion) when considering the clinical implications of stem anteversion. This study investigates the post-operative differences between anatomically-referenced and functionally-referenced stem and combined anteversion in the supine and standing positions.

Method

18 patients undergoing pre-operative analysis with the Trinity OPS® planning (Optimized Ortho, Sydney Australia, a division of Corin, UK) were recruited for post-operative assessment. Anatomic and functional stem anteversion in both the supine and standing positions were determined. The anatomic anteversion was measured from CT and referenced to the posterior condyles. The supine functional anteversion was measured from CT and referenced to the coronal plane. The standing functional anteversion was measured to the coronal plane when standing by performing a 3D/2D registration of the implants to a weight-bearing AP X-ray. Further, functional acetabular anteversion was captured to determine combined functional anteversion in the supine and standing positions.

Introduction

Despite consequent advancement in Total Knee Arthroplasty (TKA) up to 20% of patients are not satisfied after having been operated. Beside correct implantation, the design of the TKA-system is supposed to be a key factor of a successful TKA. Consequently it has been tried to restore natural kinematics by the design of the prosthesis. A medially stabilized design therefore is supposed to allow a lateral translation with a medial pivot.

Objectives

Our study compared posterior stabilized (PS) with medially stabilized (MS) TKA-design in terms of kinematics, femorotibial and patellofemoral contact patterns in vitro.

Introduction

Patients who undergo hip resurfacing, total hip arthroplasty (THA), and total knee arthroplasty (TKA) are frequently assessed post-operatively using objective scoring indices. A small yet significant percentage of these patients report specific unfulfilled functions following surgery, indicating unmet expectations. The purpose of this study was to examine the types of functional deficits reported for each class of surgery, how frequently these limitations occur, and the demographic of patients who experience/report these limitations.

Methods

Four groups of subjects were enrolled in this study: (i) 111 hip resurfacing patients at an average of 14 months after resurfacing, (ii) 170 patients at an average of 16 months post-primary THA, (iii) 61 patients at an average of 12 months post-primary TKA, and (iv) 64 control subjects with no history of hip or knee surgery or pathology. Each participant completed a self-administered Hip Function Questionnaire, Knee Function Questionnaire, or Hip Resurfacing Questionnaire which assessed each subject's overall satisfaction and expectations following surgery. The questionnaires included numerical scores of post-operative function as well as an open-ended question which inquired “Is there anything your knee/hip keeps you from doing?”

Introduction

Patients who undergo hip resurfacing, total hip arthroplasty (THA), and total knee arthroplasty (TKA) are frequently assessed post-operatively using objective scoring indices. A small yet significant percentage of these patients report pain and discomfort related to specific physical activities following surgery. The purpose of this study was to examine the types of activities which prove difficult for patients for each class of surgery, how important these activities are to the individual patients, and the demographic of patients who experience/report these limitations.

Methods

Four groups of subjects were enrolled in this study: (i) 111 hip resurfacing patients at an average of 14 months after resurfacing, (ii) 170 patients at an average of 16 months post-primary THA, (iii) 61 patients at an average of 12 months post-primary TKA, and (iv) 64 control subjects with no history of hip or knee surgery or pathology. Each participant completed a self-administered Hip Function Questionnaire, Knee Function Questionnaire, or Hip Resurfacing Questionnaire which assessed each subject's overall satisfaction and expectations following surgery. The questionnaires included a section with 58 physical activities and asked the patients to rate the activities based on frequency of participation, importance of the activity, and how much their knee or hip bothered them when performing the activity.

Introduction

Given the association of osteoarthritis with obesity, the typical patient requiring total knee arthroplasty (TKA) is often obese. Obesity has been shown to negatively influence outcomes following TKA, as it is associated with increased perioperative complications and poorer clinical and functional outcomes. Achieving proper limb alignment can be more difficult in the obese patient, potentially requiring a longer operation compared to non-obese patients. Patient specific instrumentation (PSI), a technique that utilizes MR- or CT-based customized guides for intraoperative cutting block placement, may offer a more efficient alternative to manual instruments for the obese patient. We hypothesize that the additional information provided by a preoperative MRI or CT may allow surgeons to achieve better alignment in less time compared to manual instrumentation. The purpose of this study was to assess whether PSI offers an improved operation length or limb alignment compared to manual instruments for nonmorbidly and morbidly obese patients.

Methods

In this retrospective cohort study, we evaluated 77 PSI TKA and 25 manual TKA performed in obese patients (BMI≥30) between February 2013 and May 2015. During this period, all patients underwent PSI TKA unless unable to undergo MR scanning. All cases were performed by a single experienced surgeon and utilized a single implant system (Zimmer Persona™). PSI cases were performed using the MR-based Zimmer Patient Specific Instrumentation system. Tourniquet times were recorded to determine length of operation. Long-standing radiographs were obtained preoperatively and 4-weeks postoperatively to evaluate limb alignment. Cases were subdivided by nonmorbid obesity (30≤BMI<40) and morbid obesity (BMI≥40) to assess the effect of increasing obesity on outcomes.

Introduction

Hip modular implants provide real advantages to patients and surgeons: the opportunity to restore the natural anatomy, to correct discrepancy is positioning, etc…

Nevertheless, recent publication showed the weakness of these prostheses. A review of the literature on this phenomenon is carried out, and shows that fretting fatigue and fretting wear is often pointed out to explain these issues.

Objectives

The goal of this project is to optimise these products, carrying out advanced simulations with criterion that allow to compare the behaviour regarding fretting in the modularity.

Introduction

Metal on metal hip resurfacing (MoM HR) is attractive for young active patients. Patients with osteonecrosis of the femoral head (ONFH) are relatively young. HR can be an option of treatment, however, long-term stability of the femoral component is a concern because of the necrotic lesion in the femoral head. There is also a concern of ARMD for MoM implants. The purpose of this study is review a 10 year outcome of a consecutive patients with ONFH who underwent MoM HR.

Methods

The subjects of this study were 30 hips of 26 patients with ONFH who underwent HR between 1998 and 2004. There were 21 hips of 18 males and 9 hips of 8 females. The average age at operation was 40 years (range, 20–63 years). 19 ONFHs were induced by steroid and 11 ONFHs were alcohol related. According to the Japanese Investigation Committee classification, there were 8 hips with Type C1 and 22 hips with Type C2. There were 16 hips in stage 3A, 7 hips in Stage 3B, and 7 hips in Stage 4. Operation was performed through a posterior approach. A fragile necrotic bone was curettage thoroughly and the defect was filled with cement.

Objective

Several researchers have reported that imageless navigation is a reliable technique and results in more precise cup placement compared to conventional freehand techniques, however, few studies have been reported about the accuracy of the femoral stem placement. The primary aim of this study was to evaluate the precision of an imageless navigation system in measuring the limb length change. The secondary aim was to evaluate LLD following imageless navigation THA with modified registration technique in semilateral decubitus position.

Methods

The authors reviewed 66 cases receiving cementless THA with imageless navigation from September 2013 to December 2014. The radiographic limb length change measured from pre-operative and post-operative digital x-ray was compared with the intraoperative calculation by the navigation system. Postoperative LLD in unilateral cases and second operation of staged bilateral cases were also recorded.

Background

The short stem prosthesis showed good results in patients with primary osteoarthritis. However, there were a few studies about the short stem THA in patients with osteonecrosis of the femoral head (ONFH).

Objective

To evaluate the clinical and radiographic results of the short stem THA in patients with ONFH. The authors hypothesized that the short stem THA would be a promising procedure for patients with ONFH.

Backgrounds

It is well accepted that gap balancing is one of the important step for total knee arthroplasty (TKA). In order to evaluate gap balancing during operation, many tension devises have been used and developed. However, during operation, proper load to be applied, ideal gap amount, appropriate angle formed between femoral component and tibial cut surface are not clearly defined. Understanding the relationship between applied load and gap pattern will provide important information. The purpose of this study is to precisely analyze gap amount and inclination in extension and flexion using digital analyzer during TKA and characterize gap pattern.

Methods

We analyzed 39 knees in 39 cases that underwent TKA with Scorpio NRG PS knee prosthesis operated by modified gap balancing technique. A customized digital knee balancer was manufactured applying load cell, angle sensor, and gap sensor in the selected part within offset seesaw type balancer (Fig 1). It can measure three values (gap, angle and force) at the same time and automatically record the values. After bone cut for femur, tibia, and patella, femoral component trial was inserted to the femur. Then gap length and inclination angle between femoral condyle surface and tibial cut surface was analyzed in extension and at 90 degrees knee flexion with gradually increasing opening torque. Inclination was expressed by positive degrees when lateral side opened. Serial data was recorded automatically and analyzed.

Introduction

Total hip arthroplasty (THA) is one of the most common orthopedic surgeries. The procedure is sophisticated and in addition to several factors affecting the outcomes such as patient's status, surgeon's expertise and implant type, using appropriate surgical tools is necessary. Acetabular component implantation necessitates the surgeon to ream the acetabular fossa which is time consuming and devastating. Utilizing currently-used reamers (figure 1), the size of the tool must be changed repeatedly for 5–20 times within a surgery. In every stage, the size of the reamer is increased up to 1–2 mm. This tiring process takes 15–30 minutes and is associated with some injuries to the soft tissue. Furthermore, the risk of mistakes is considerable.

Objectives

Designing a new system which overcomes the limitations and defects with previous systems

Introduction

Large variations in knee kinematics existed after conventional TKA. Different design of TKA showed different intra-operative kinematics with navigation system.

Purpose

The purpose of this study was to compare the kinematics of the three different types of prosthesis in navigation-based in vivo simulation.

(Material and Method) Studies were carried out on 15 osteoarthritis Knees using the CT-free navigation system (Kolibri Knee, Brain LAB). Fourteen patients were female and one patient was male with mean age of 72 years. Five knees were implanted with the CR knee, 5 knees were implanted with the PS knee and 5 knees were implanted with PS mobile knee by navigated measured resection technique (PFC-sigma knee system, DePuy, Warsaw, IN). Intra-operative knee kinematics during passive range of motion from full extension to 130 degrees of knee flexion was measured after implantation while patella reduced and tourniquet released. While supporting the foot with one hand, the surgeon used his opposite hand to gently lift the thigh, flexing the hip and knee. Three types of prosthesis were compared for following factors: Presence of condylar lift-off (the gap difference greater than 1mm between medial gap and lateral gap) and anterior-posterior (AP) displacement of the center of femur relative to the tibia.

Introduction

In cemented total hip arthroplasty (THA), proper cement mantle thickness in the femoral canal is still controversial subject. It is widely accepted that the cement mantle around a femoral stem should be at least 2 mm in thickness. But articles from France reported good long-term result with thin cement mantle. It is so called “The French paradox”. We have already reported that the greater compressive force at the cement-bone interface was seen in collarless polished tapered (CPT, Zimmer, USA) stem with thick cement mantle than that with thin cement mantle. However, the stem with thick cement mantle subsided more than with thin mantle. It may have a possibility to cause an early mechanical failure of cemented THA. We compared to stem and cement subsidence in various cement mantles using tantalum ball into cement in this study.

Methods

A cemented stem model was used for this study with a CPT stem into composite femur.

Three sizes of CPT stems (No. 1, No. 2 and No. 3) and one size composite femur were prepared for this study. We inserted two stems for each size, for a total of six stems. Composite femurs were reamed with a No. 3 rasp, and various size of stem was fixed with cement in each composite femur to make a various thicknesses of cement mantle. Two to three tantalum marker balls were injected into the cement in each femur before cement was hardened. 1-Hz dynamic load applied to the stems for half a-million cycles. Each 16 hours of loading was followed by 8 hours without loading. We used micro-CT before and after loading to measure the movement of the tantalum balls in three dimensions. And we analyzed occupation ratio of stem in the femoral canal by computed reconstructed three dimensional model of bone cement and stem.

Objective

The optimal positioning of the acetabular component is a relevant prognostic factor in total hip arthroplasty (THA). Because of substantial errors of manual technique in cup placement even with experienced surgeon, computer aided navigation system has been developed in recent years. However, existence of the hardware around acetabulum likely deteriorates the accuracy of the navigation system, namely in revision THA case and postoperative status of pelvic fracture. Here we report a case who we successfully performed THA using CT based navigation system although there were multiple hardware around acetabulum due to osteosynthesis for the previous pelvic fracture.

Case presentation

A forty-one years old man presented with intolerable hip pain with severe radiographic osteoarthritic findings in left hip joint. He had sustained left pelvic fracture and posterior hip dislocation due to traffic accident and undergone osteosynthesis using multiple plates and screws when he was forty years old. However, progressive collapsing of femoral head and acetabulum occurred. Then, we indicated THA for his situation and planned to apply the CT based navigation system (Stryker CT based hip Ver.1.1 softwear and Cart II system). Preoperative workup revealed incomplete union of posterior and superior acetabular wall and we had to retain plates and screws for the stable fixation of acetabular cup. The existence of the hardware made it complicated to perform three dimensional planning and templating. Meticulous surface editing of pelvis to exclude the metal artifact and fibrocartilagenous tissue was needed to achieve accurate surface registration. In the operation room, we had to use unusual way of registration to complete two steps of registration. In the first step (roughly matching between patient's physical pelvic surface and edited pelvic surface in work station using corresponding 5 points), we utilized head of screw and hole of the plate which we could easily identify intraoperatively, in addition to ASIS and innominate groove. In the second step (strict matching using more than 30 points of pelvic surface), we had to identify the pelvic bony surface, as excluding the metal surface and fibrocartilagenous tissue such as fracture callus. These efforts enabled us to accomplish substantial accuracy of registration with RMS of 0.5 mm. Final cup orientation at the end of surgery was 41° of inclination and 25° of anteversion. Postoperative CT scan revealed that cup placement angle was 40° of inclination and 25° of anteversion, almost identical with intraoperative value.

Objective

While the short-stem design is not a new concept, interest has risen with increasing utilization of less invasive techniques. Especially, short stems are easier to insert through the direct anterior approach. In the radiographic evaluation of patients who underwent primary uncemented total hip arthroplasty (THA) using a TaperLoc Microplasty femoral component (Biomet, Warsaw, IN, USA), cortical hypertrophy was occasionally detected on three-month postoperative radiographs. The purpose of this study was to evaluate the radiographic changes associated with cortical hypertrophy of the femur three months postoperatively.

Methods

Between May 2010 and September 2014, 645 hips in 519 patients who received the TaperLoc Microplasty stem were evaluated. Six hips in four patients were lost to follow-up. Finally, 639 hips in 515 patients were included in this study; 248 hips underwent bilateral simultaneous THA and 391 hips underwent unilateral THA. There were 103 males and 412 females (average age, 63 ± 10.1 years; average height, 156 ± 8.13 cm; and average weight, 58 ± 12.2 kg). The postoperative radiographs immediately taken after the operation and three months postoperatively were compared. We evaluated cortical hypertrophy around the stem. Cortical hypertrophy >2 mm on anterior-posterior X-ray was defined as “excessive periosteal reaction” (Figure 1).

INTRODUCTION

Several papers have reported the efficacy of an imageless navigation system in acetabular cup orientation during total hip arthroplasty (THA). Also, an imageless navigation system is useful for recovering leg length discrepancy. However, no study has evaluated the accuracy of the stem antetorsion angle (SAA) with an imageless navigation system in THA. The purpose of this study was to evaluate the accuracy of the stem antetorsion angles, which were measured by CT with the CT-free navigation system. Also, we evaluate the factors that affect the inaccuracy.

MATERIALS AND METHODS

CT evaluation was performed in 60 patients (60 joints) who underwent primary THA from December 2011 to March 2014. Fifty-nine patients were female. The mean age at surgery was 67 years. The mean BMI at surgery was 24.0 kg/m2. Fifty-four patients had osteoarthrosis, 5 patients had osteonecrosis, and 1 patient had femoral neck fracture. All surgeries were performed in the supine position with the direct anterior approach. The OrthoPilot imageless navigation system was used during surgery. An Excia stem was used in 47 patients and a Bicontact stem was used in the other 13.

Evaluation of SAA was carried out. Instead of SAA, the navigation indicates the rasp antetorsion angle based on the hip-knee-ankle plane during surgery. SAA based on the posterior condylar plane was measured with CT by using 3D THA plannning software. The accuracy of the imageless navigation system was evaluated by comparison of the navigation values obtained during surgery with the CT measured values. Correlations were analyzed with Pearson correlation analysis.

INTRODUCTION

Corrosion of modular tapers is increasingly recognized as a source of adverse tissue reaction (ALTR) and revision surgery in total hip arthroplasty (THA). The incidence of corrosion and rate of revision for ALTR may differ among different types of implants.

OBJECTIVE

The objective of this study was to determine if a difference exists in rate of THA revision for corrosion and ALTR with tapered broach only stems compared to ream-broach femoral stems.

Introduction

Dual modular femoral stems for total hip arthroplasty were initially introduced to optimize joint biomechanics. These implants have been recalled due to fretting and crevice corrosion at the stem-neck interface, ultimately necessitating revision in a significant number of patients. At our institution we had experience with the Rejuvenate (Stryker, Mahwah, NJ) dual modular stem from 2009 until 2011 before it's recall in 2012. This study identifies complications encountered in patients requiring revision of this prosthesis.

Methods

We retrospectively identified all patients who had one particular dual modular stem using our registry database. All patients’ charts and imaging was reviewed using our electronic medical records and digital imaging programs. Patients’ age, gender, revision date, intraoperative and postoperative complications, need for subsequent surgery were identified.

Introduction

Acetabular osteotomy is considered to be an alternative treatment for acetabular dysplasia, particularly in adolescents and young adults because the long-term results of total hip arthroplasty (THA) in such patients remain controversial. To our knowledge, few reports have described the relationship between the types of osteotomies and surgical difficulty. We compared the operative and clinical results of THA following the 3 main types of acetabular osteotomies, including Chiari osteotomy, rotational periacetabular osteotomy (RAO), and shelf acetabuloplasty.

Methods

Operative records of 13 hips following Chiari osteotomy (Chiari group), 22 hips following RAO (RAO group), and 16 hips following shelf acetabuloplasty (Shelf group) were retrospectively reviewed. Operative records of 2475 primary THAs without previous osteotomies during the same period were reviewed as a control. The direct anterior approach was used for all hips

Background

Pre-operative autologous blood donation is recommended as a means of reducing the need for allogeneic transfusion before simultaneous bilateral total hip arthroplasty (THA). However, there have been few reports on the optimal amount of autologous donation for this procedure. In this study we sought to determine the amount of autologous blood required for patient undergoing simultaneous bilateral THA using the direct anterior approach.

Methods

We retrospectively enrolled 325 consecutive patients (650 hips) underwent simultaneous bilateral primary THA from January 2012 to June 2014. Thirty-three patients were men and 290 patients were women. The patients’ mean age at THA was 59.1 years. All THAs were performed using the direct anterior approach. Intraoperative blood salvage was applied for all patients and postoperative blood salvage was not applied for any patients.

Introduction

IBBC (interfacial bioactive bone cement method, Oonishi) (1) is an excellent technique for augmenting cement-bone fixation in the long term. However, the technique is difficult and there are concerns over some points, such as bleeding control, disturbance of cement intrusion to anchoring holes by granules, difficulty of the uniform granular dispersion to the acetabular bone (Zone 1 in particular). To improve this technique, we have modified IBBC (M-IBBC), and investigated the short-term clinical results and radiographic changes.

Materials and Methods

K-MAX HS-3 THA (Kyocera Medical, Japan), with cemented stem and all polyethylene cemented socket, was used for THA implants. Basically the third generation cementing technique was used for THA using bone cement. The socket fixation was performed with bone cement (Endurance, DePuy) and hydroxyapatite (HA) granules (Ca10(PO4)6(OH)2, Boneceram P; G-2, Olympus, Japan). In original IBBC technique, HA granules were dispersed on reamed acetabulum before cementing. In M-IBBC technique, HA granules were attached to bone cement on plastic plate, then inserted to reamed acetabulum and pressurized. HA granules (G-2) are 0.3–0.6mm in size, with 35–38% porosity and sintered at 1150â��. 51 hip joints (49 cases) were operated between June 2010 and December 2011, and followed. The average follow-up was 3.9 years, and average age at operation was 66.5 years. The clinical results were evaluated by Japan Orthopaedic Association Hip Score (JOA score), and X-p findings were evaluated using antero-posterior radiographs. The locations of radiolucent lines were identified according to the zones described by Delee and Charnley for acetabular components, and Zone 1 was divided into two parts, outer Zone 1a and inner Zone 1b.

Introduction

Post cam is useful to realize the intrinsic stability of a posterior-stabilized (PS) knee prosthesis replaced for a case with the severe degeneration. Some retrieval studies reveal the ultrahigh molecular weight polyethylene (UHMWPE) deformation or severe failure of the tibial post of PS knee. Strength of the tibial post of available design is obviously insufficient to prevent the severe deformation. The large size post might, however, shorten the range of knee motion. Therefore, minimally required size of the post should be clarified for polyethylene inserts. In the present study, we performed finite element (FE) analysis assumed the mechanical conditions of a tibial post in a PS knee and aimed to design criterion of a post of polyethylene insert of a knee prosthesis.

Method

The shape of three commercially available knee prostheses, product A, B, and C was referred as PS knee prosthesis. The contour of the metallic femoral component and the UHMWPE insert were digitized by a computed tomography apparatus. Three dimensional finite elements were generated by modeling software (Simpleware, Ltd. UK) as four-node tetrahedral elements. In FE analysis, we used LS-DYNA ver.971 (Livemore Software Technology Corp. USA) as the software and Endeaver Pro-4500 (EPSON Corp. Japan) as the hardware. These bottoms of the tibial insert were fully constrained. The value of 30MPa was defined as yield stress of UHMWPE. 500N posterior load was applied to each femoral component at 10 degree hyperextension. Then, 1000N anterior load at 120 degree flexion, after tibial insert was located 10 degree internal rotation (Fig. 1). These loads were assumed to realize the two types of tibial post impingement under several kinds of knee motions. The distributed values of von Mises stress and plastic strain on the tibial post were shown as the results of the analysis.

Purpose

Our primary purpose was to study the rate of occurrence and the natural course of pseudotumors in patients who had not required a revision procedure. Our secondary purpose was to see if there is a relationship between serum metal ion analysis and clinical symptoms with metal-on-metal (MOM) hip arthroplasty.

Patients and Methods

We used repeated metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) to screen 17 unrevised hips (mean patient age 63.0 years, 43 to 83 years) with pseudotumors and 26 hips (mean patient age 63.2 years, 47 to 83 years) without pseudotumors. Patients with 17 MOM, 17 ceramic-on-polyethylene (COP) and 7 ceramic on ceramic (COC) who had undergone repeated MARS MRI were evaluated with or without any symptoms. We utilized MARS MRI to score the type of pseudotumors using the Hart method. The mean post-operative time to the first MARS MRI scan was 30.0 months (8 to 96), and the time between the first and the second MARS MRI scan was eleven months (6 to 12). Serum Cr and Co ion measurements were undertaken at the time of both MRIs and analyzed only after MOM total hip arthroplasty.

Background

Implants based on the polyetheretherketon (PEEK) polymer have been developed in the last decade as an alternative to conventional metallic devices. PEEK devices may provide several advantages over the use of conventional orthopedic materials, including the lack of metal allergies, radiolucency, low artifacts on magnetic resonance imaging scans and the possibility of tailoring mechanical properties. The purpose of this study was to evaluate the clinical results at mean 24-month follow-up using a new plate made of carbon-fiber-reinforced polyetheretherketon (CFR-PEEK) for the treatment of distal radius fractures.

Materials and methods

We performed a prospective study including all patients who were treated for unstable distal radius fracture with a CFR-PEEK volar fixed angle plate. We included 70 consecutive fractures of AO types B and C that remained displaced after an initial attempt at reduction. The fractures were classified according to the AO classification: 35 fractures were type C1, 13 were type C2, 6 were type C3, 5 were type B1 and 11 were type B2.

Introduction

Recently, tibial insert design of cruciate-substituting (CS) polyethylene insert is employed. However, in vivo kinematics of using CS polyethylene insert is still unclear. In this study, it is hypothesized that CS polyethylene insert leads to stability of femolo-tibial joint as well as posterior-stabilized (PS) polyethylene insert, even if PCL is sacrificed after TKA. The purpose of this study is an investigation of in vivo kinematics of femolo-tibial joint with use of CS polyethylene insert before and after PCL resction using computer assisted navigation system intra-operatively in TKA.

Materials and Methods

Twenty-four consecutive patients who had knees of osteoarthritis with varus deformity were investigated in this study. All TKAs (Triathlon, Stryker) were performed using computer assisted navigation system. In all patients, difference between extension and flexion gap was under 3mm after bony cut of femur and tibia. During surgery, CS polyethylene tibial trial insert were inserted after trial implantation of femoral and tibial components, before and after resection of PCL, respectively. The kinematic parameters of the soft-tissue balance, and amount of coronal (valgus/varus), sagittal (anterior/posterior) and rotational relative movement between femur and tibia were obtained by interpreting kinematics, which display tables throughout the range of motion (ROM) (Figure1). During record of kinematics, the surgeon gently lifted the experimental thigh three times, flexing the hip and knee. In each ROM (30, 45, 60, 90, max degrees), the data were analyzed with paired t-test, and an ANOVA test, and mean values were compared by the multiple comparison test (Turkey HSD test) (p < 0.05).

Introduction

Acute poliomyelitis is a very rare disease in western countries, however the remnant of the pathology can be find among the adult patients. In poliomyelitis, sensation is normal and patients may suffer from painful etiologies. Total knee arthroplasty (TKA) with non-hinged or semi hinged prosthesis systems may be a good options to relief the pain in poliomyelitic patients, however the knee remains unstable. Using the hinged system implant may be the good option to resolve the late. Although the main concern in case of hinged implant usage is the mechanical stress which is directly transferred to the bone surface in contact with the implant. This may leads to implant mobilization and consequently failure.

Methods and Materials

From 2004 to 2014, 14 TKA were performed in poliomyelitic patients with secondary knee pain. All patients were presented with extensor compartment hyposthenia and reduced antigravity function. In all patients a third generation rotating hinged knees (RHK) implant system (Zimmer, Warsaw, IN, USA) was applied. Bilateral TKA was performed in only one case. The mean age at the time of surgery was 56 years (ranged 48–77). Mean follow-up was 60 months (24–112).

Results Due to post-operative infection, one patient underwent knee arthrodesis and excluded from the study. In one case, patellar fracture occurred 3 month following the surgery and treated non-surgically. Pain relief was observed in all patients following the surgery without any major complication. Mean objective score according to knee society knee scoring system was improved from 28 (16–51) preoperatively to 79 (72–88) postoperatively. Mean functional score was improved from 24 (5–35) preoperatively to 66 (50–70) postoperatively. At last follow up the mean range of motion was 90° (75°−100°). Following radiographic control at last follow-up all implants was stable without any sign of failure such as mobilization, radiolucency line or osteolysis.

INTRODUCTION

Total hip arthroplasty (THA) is a very successful orthopaedic treatment with 15 years implant survival reaching 95%, but decreasing age and increasing life expectancy of THA patients ask for much longer lasting solutions. Shorter and more flexible cementless stems are of high interest as these allow to maintain maximum bone stock and reduce adverse long-term bone remodeling.1 However, decreasing stem length and reducing implant stiffness might compromise the initial stability by excessively increasing interfacial stresses. In general, a good balance between implant stability and reduced stress shielding must be provided to obtain durable THA reconstruction.2

This finite element (FE) study aimed to evaluate primary stability and bone remodeling of a new design of short hip implant with solid and U-shaped cross-section.

MATERIALS AND METHODS

The long tapered Quadra-H stem and the short SMS implants (Medacta International, Castel San Pietro, Switzerland) were compared in this study (Figure 1). A FE model of a femur was based on calibrated CT data of an 81 year-old male (osteopenic bone quality). Both titanium alloy implants were assigned an elastic modulus of 105 GPa and the Poisson's ratios were set to 0.3. Initial stability simulations included the hip joint force and all muscle loads during a full cycle of normal walking as calculated in AnyBody software (Anybody Technology AS, Denmark), whereas the remodeling simulation used the peak loads from normal walking and stair climbing activities. Initial stability results are presented as micromotions on the implant surface with a threshold of 40 µm.3 Bone remodeling outcomes are represented in a form of simulated Dual X-ray Absorptiometry (DEXA) scans and the quantitative bone mineral density (BMD) changes in 7 periprosthetic zones.

Introduction

Migration of the trial femoral head is a rarely occurring complication of total hip arthroplasty (THA) performed using the anterolateral approach (ALA). This migration of the trial femoral head under the rectus femoris is extremely risky because of the anatomical situation. Analyzing the morphological character of a case of migration may help us to avoid this risk.

Objective

We analyzed the three-dimensional bone morphology using computed tomography (CT) scan images to investigate the physiological characteristics of five migration cases.

Background

The main reasons for hip prosthesis failure are aseptic loosening and periprosthetic joint infection (PJI). The real frequency of PJI is probably largely underestimated because of non-standardized definition criteria, diagnostic procedure, treatment algorithm and other confounders. Therefore, data from joint registries are not reflecting the frequency of PJI and can be misleading; particularly low-grade PJI can be frequently misdiagnosed as aseptic failure. Therefore, prospective clinical studies with standardized protocol, comprehensive diagnostic procedure and sufficient follow-up should be performed. Sonication of explanted prosthesis is highly sensitive for detection of biofilms on prosthetic surface and allows quantitative analysis of biofilm formation. We hypothesize that by using sonication, ceramic components (BIOLOX®delta, BIOLOX®forte) will show higher resistance against biofilm adhesion compared to polyethylene (PE) and metal (CoCrMo).

Methods

In this prospective multicentre study (level of evidence: Ia), we included all consecutive adults ≥18 years of age, who underwent explantation of the hip prosthesis for infection or aseptic reason. Excluded were patients in whom part of the prosthetic components were retained. A standardized and comprehensive diagnostic algorithm was applied, including sonication of all removed prosthetic components for qualitative and quantitative microbiological analysis (ultrasound bath 40 kHz, 1 W/cm2, 1 min). Individual components (metal, PE, ceramic) were separately placed in sterile boxes for investigation. All patients were simultaneously included in the European Prosthetic joint infection cohort (EPJIC, www.epjic.org) to ensure long-term follow-up.

Introduction

Presentation of our outcome in implant survival and clinical function using rotating-hinge knee prosthesis in revision total knee arthroplasty.

Method

A retrospective review of 44 revision TKA containing 21 RHK (Biomet) and 23 MRH (Stryker).

The patient population consisted of 27 women and 17 men with an average age of 75 years at the time of the revision. The mean follow-up period was 13 months. The clinical and functional results were evaluated according to the Knee-Society-Score (KSS) after 3, 6, 12, 24 and 36 months together with a x-ray.

Introduction

Total knee arthroplasty (TKA) is the second most common and successful joint replacement in orthopedics. Due to long-term results the problem of aseptic loosening, implant failure and hypersensitivity to metal ions remain. Therefore the introduction of a new TKA with ceramic tibial and femoral components is introduced.

Methods

It is the aim of this prospective study to compare a full delta ceramic unconstrained TKA with its conventional counterpart (Brehm BPK-S). Each group includes 40 patients without demopgraphic differenve. All TKAs are cemented with the same surgical technique using a rotating polyethylene insert. Clinical and radiological evaluation were performed preoperatively, and 3, 12 and 24 months postoperatively using the oxford knee score, the KSS, the VAS and the EQ-5d.

Introduction

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.

Materials and Methods

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 [Fig 1.A]. A compressive load of 1,600N through the femoral component was applied to the composite tibia FE model integrated with the tibia component, sharing by the medial and lateral condyles, simulating a stance phase before toe-off [Fig 1.B].

Patients and methods

In 40 patients an ankle arthrodesis was performed between 1998 and 2012. Group A was formed by 20 consecutive patients treated by spezial trained Foot and Ankle surgeons and group B was formed by 20 patients treted by general orthopaedic surgeons. The average age in group A at the time of surgery was 59,9y (34 to79y) compared to 63,4y (41 to 80y) in group B. The average follow up was 34 months respectively 32 months after surgery. The study included a spezial questionnaire with the AOFAS score and rating of patients dissatisfaction. The successful healing of the arthrodesis was determied by using standardized radiographs, Furthermore a pedobarography, and a videoanalyzis of the walking was incuded.

Results

All procedures in group A were performed using an anterior approach. Neither pseudarthroses, equinus or other malositions were detected in this group.

In group B wurdenin 16 patients an anterior and in 4 patients a lateral approach was used. Complications included 3 pseudarthroses, 4 equinus malpositions, 4 varus malpositions, 4 valgus malpositions and 8 penetrations of the subtalar joint.

The AOFAS score on average was 78 (46–92) points in group A and 75 (34 – 94) in group B.

Introduction

Corrosion at the modular junction of the femoral component in total hip arthroplasty (THA) was considered as a cause of adverse local tissue reaction in recent years. We reported three adverse local tissue reaction cases after total hip arthroplasty using the same modular neck stem in this study.

Materials and Methods

We have been essentially using the same titanium modular neck stem system and the same combination bearing surface of 26mm cobalt chromium (CoCr) head and highly cross linked polyethylene line for primary total hip arthroplasty since November 2009. Three female showed adverse local tissue reaction and had additional surgical treatment after the THA.

INTRODUCTION

To obtain appropriate joint gap and soft tissue balance, and to correct the lower limb alignment are important factor to achieve success of total knee arthroplasty (TKA). A variety of computer-assisted navigation systems have been developed to implant the component accurately during TKA. Although, the effects of the navigation system on the joint gap and soft tissue balance are unclear. The purpose of the present study was to investigate the influence of accelerometer-based portable navigation system on the intraoperative joint gap and soft tissue balance.

METHODS

Between March 2014 and March 2015, 36 consecutive primary TKAs were performed using a mobile-bearing posterior stabilized (PS) TKA (Vanguard RP; Biomet) for varus osteoarthritis. Of the 36 knees, 26 knees using the accelerometer-based portable computer navigation system (KneeAlign2; OrthAlign) (N group), and 10 knees using conventional alignment guide (femur side; intramedullary rod, tibia side; extramedullary guide) (C group). The intraoperative joint gap and soft tissue balance were measured using tensor device throughout a full range of motion (0°, 30°, 45°, 60°, 90°, 120°and full flexion) at 120N of distraction force. The postoperative component coronal alignment was measured with standing anteroposterior hip-to-ankle radiographs.

Introduction

Proper acetabular cup placement is very important factor for successful clinical results in total hip arthroplasty (THA). Malposition of acetabular cup has been linked to increased rates of dislocation, impingement, pelvic osteolysis, cup migration, leg length discrepancy and polyethylene wear. Recently, some authors reported usefulness of navigation systems to set the acetabular cups with correct position. The purpose of this study is to evaluate the accuracy of acetabular cup placement in THA using computed tomography (CT)-based navigation system.

Material and Methods

Subjects were 235 hip joints we performed primary THA using CT based navigation system (Stryker® Navigation System, Stryker Corporation, Kalamazoo, MI, USA) from 2008 to 2014 and could assess the implant position by postoperative CT images. Their average age was 65.1 years (range 35–88). In all cases, non-cemented acetabular cups were implanted. TriAD cups (Stryker®) were used in 31 hips, and Tritanium cups (Stryker®) were used in 15 hips, and Trident cups (Stryker®) were used in 189 hips. Registration in this navigation system used surface matching system. We designed cup implantation using preoperative CT images and 3-dimensional (3-D) templates. The planned position of acetabular cup was in principle 40 degrees of inclination and 20 degrees of anteversion. However, we adjusted the better position of the cups according to pelvic tilt and femoral neck anteversion. When we placed acetabular cups, the position, inclination and anteversion, were measured by navigation system. After surgery, the positions of the cups were measured using postoperative CT images, navigation software and 3-D templates. Postoperative position using CT images were adjusted according to preoperative pelvic plane. The discrepancies between intraoperative navigation data and postoperative CT images data were analyzed as accuracy of navigation system in cup placement.

Introduction

Total Knee Arthroplasty (TKA) is an established procedure for relieving patients of pain and functional degradation associated with end-stage osteoarthritis of the knee. Historically, alignment of components in TKA has focused on a ‘reconstructive’ approach neutral to the mechanical axes of the femur and tibia coupled with ligament balancing to achieve a balanced state. More recently, Howell et al. have proposed an alternate approach to TKA alignment, called kinematic alignment. (Howell, 2012) This approach seeks to position the implants to reproduce underlying, pre-disease state femoral condylar and tibial plateau morphology, and in doing is ‘restorative’ of the patients underlying knee kinematic behaviour rather than ‘reconstructive’. While some promising early clinical results have been reported at the RCT level (Dosset, 2014), in vivo comparisons of the kinematic outcome achieved at patient specific levels with the two alignment techniques remain an impossibility. The aim of this research is to develop and report preliminary findings of a means of simulating both alignment techniques on a number of patients.

Method

In 20 TKR subjects, 3D geometry of the patient was reconstructed from preoperative CT scans, which were then used to define a patient specific soft tissue attachment model. The knees were then modelled passing through a 0 to 140 degree flexion cycle post TKR under each alignment technique. A multi-radius CR knee design has been used to model the TKA under each alignment paradigm. Kinematic measurements of femoral rollback, internal to external rotation, coronal plane joint torque, patella shear force and varus-valgus angulation are reported at 5, 30, 60, 90 and 120 degrees of flexion. Student's paired 2 sample t-tests are used to determine significant differences in means of the kinematic variables.

Introduction

Despite generally excellent patient outcomes for Total Knee Arthroplasty (TKA), there remains a contingent of patients, up to 20%, who are not satisfied with the outcome of their procedure. (Beswick, 2012) There has been a large amount of research into identifying the factors driving these poor patient outcomes, with increasing recognition of the role of non-surgical factors in predicting achieved outcomes. However, most of this research has been based on single database or registry sources and so has inherited the limitations of its source data. The aim of this work is to develop a predictive model that uses expert knowledge modelling in conjunction with data sources to build a predictive model of TKR patient outcomes.

Method

The preliminary Bayesian Belief Network (BBN) developed and presented here uses data from the Osteoarthritis Initiative, a National Institute of Health funded observational study targeting improved diagnosis and monitoring of osteoarthritis. From this data set, a pared down subset of patient outcome relevant preoperative questionnaire sets has been extracted. The BBN structure provides a flexible platform that handles missing data and varying data collection preferences between surgeons, in addition to temporally updating its predictions as the patient progresses through pre and postoperative milestones in their recovery. In addition, data collected using wearable activity monitoring devices has been integrated. An expert knowledge modelling process relying on the experience of the practicing surgical authors has been used to handle missing cross-correlation observations between the two sources of data.

Introduction

Total Knee Replacement (TKR) alignment measured intra-operatively with Navigation has been shown to differ from that observed in long leg radiographs (Deep 2011). Potential explanations for this discrepancy may be the effect of weight bearing or the dynamic contributions of soft tissue loads.

Method

A validated, 3D, dynamic patient specific musculoskeletal model was used to analyse 85 post-operative CT scans using a common implant design. Differences in coronal and axial plane tibio-femoral alignment in three separate scenarios were measured:

Scenario number two illustrates the tibio-femoral alignment when the femoral component sits congruently on the tibia with no soft tissue acting whereas scenario three is progression of scenario number two with weight applied and all ligaments are active. Two tailed paired students t-test were used to determine significant differences in the means of absolute difference of axial and coronal alignments.

Purpose

To assess the reliability of a biomimetic osteochondral scaffold Maioregen (Finceramica Faenza SpA, Faenza, Italt) as a salvage and joint-preserving procedure in the treatment of late stages of osteonecrosis of the knee.

Methods

Nine active patients aged under 65 year presenting with clinical and radiological signs of SPONK were treated with a biomimetic osteochondral scaffold. All patients were clinically evaluated preoperatively and yearly with a minimum follow-up of 2 years. Subjective IKDC and Lysholm Knee Scale were used to assess clinical outcome. Pre-operative and post-operative pain was quantified with VAS scale. Activity level were evaluated pre-operatively and at follow-up according to Tegner Activity Scale.

Purpose

Osteochondral lesions of the knee are relatively common both in young and senior population. The very disabling clinical symptoms, in association to the scarce regenerative capacity of the articular cartilage and the increased risk of developing a secondary osteoarthritis make an effective treatment mandatory.

Methods and Materials

From December 2008 to January 2013, 34 patients (35 knees), 24 males and 10 females (mean age 36.2 years range 14–66) underwent implant of Maioregen® (Finceramica Faenza S.P.A, Italy) biomimetic tri-layer osteochondral scaffold. In 17 cases the osteochondral lesion was cause by an osteochondritis dissecans (acute or sequela), in 13 cases by a spontaneous osteonecrosis and in 4 cases the etiology was traumatic. Patients were evaluated with subjective IKDC and Tegner Lysholm scores, VAS and Tegner Activity Scale before surgery and at regular follow up (mean follow up 38.4 months, range 13 months max 63 months).

Introduction

Hemophilia arthropathy often occurs in the ankle, knee and elbow. In contrast, hemophilic arthropathy in the hip is rare. We report short-term results of total hip arthroplasty (THA) in patients with hemophilia.

Method

Four primary THAs performed in four hemophilic patients from 2007 to 2015 were reviewed retrospectively. Two patients underwent cementless THA, and two patients had cemented THA. All patients had hemophilia A, and clotting factor replacement was performed perioperatively. Blood loss, surgery duration, complications, pre- and post-operative range of motion, and the pre- and post-operative Japanese Orthopedic Association (JOA) score were assessed.

Background

Fractures of the femoral component are well reported complications that present a challenging task in revision total hip arthroplasty. Albeit being uncommon, with an incidence of 0.23–11%, the consequences can be devastating. Its extraction being a demanding undertaking that is potentially detrimental to the remaining host bone. Several techniques have been described to address this complex issue prior to revision: drilling of the exposed part of the femoral stem and attaching a threaded extraction device, surface undercutting with an extraction device wedged in, femoral trephine techniques, creation of a femoral cortical window, an extended femoral osteotomy procedure, as well as extraction by means of retrograde nail impaction. Here we present the modified technique we employed in the revision of a failed cementless extensively porous coated femoral component that had fractured at the neck-stem interface.

Technique

The proximal femoral component was visualized and an orthopedic burr and a femoral osteotome employed surrounding the component. Utilizing a Midas Rex® MR7 drill with its metal cutting attachment, a circular recess was created in the shoulder of the femoral component. This facilitated the application of the distal end of a universal slap hammer. The component was retrieved successfully with no associated bone loss negating the need for a femoral osteotomy.

Introduction

In total hip arthroplasty (THA), it is important to define the coordinate system of the pelvis and femur for standardization in measuring the implant alignment. A coronal plane of the pelvis (functional pelvic coordinates) in supine position has been recommended as the pelvic coordinates for cup orientation and an anatomical plane of the femur (posterior condylar plane: PCP) is widely used as the femoral coordinates to measure stem or femoral anteversion. It has been reported that the pelvic sagittal tilt in supine does not change a lot after THA. However, changes in the axial rotation of the posterior condylar plane after THA have not been well studied. If the horizontal tilt of PCP of the femur in a resting position changes a lot after THA, the combined anteversion theory cannot be functional. Therefore, we evaluated the angulation changes of the posterior condylar plane after THA and analyzed the related factors by using CT images.

Methods

Forty patients (5 men and 35 women, mean age 58 years) with hip osteoarthritis who had undergone THA were the subjects of this study. CT images used for measurements were taken preoperatively (preop-CT) and 3 weeks after THA (postop-CT), and more than 2 years after THA (2nd postop-CT).

Measurements were done on the reconstructed CT images using 3D viewer software. The axial rotation of the femur was measured as the angle between the posterior condylar line (PCL) and a line through the bilateral anterior superior iliac spines. To analyze the factors relating to the rotational change of the femur, change in femoral anteversion, leg length, and leg medialization after THA were also measured. Surgical approach (posterolateral: 32 cases, direct anterior: 8 cases) was also evaluated as a factor relating to the rotational change.

Introduction

The complex process of inflammation and osteolysis due to wear particles still is not understood in detail. So far, Ultra-high-molecular-weight-polyethylene (UHMWPE) is the bearing material of choice in knee arthroplasty and revision knee arthroplasty, but there is a growing demand for alternative bearing materials with improved wear properties. Lately, increasing interest developed in the use of natural and carbon-fiber-reinforced-poly-ether-ether-ketones (CFR-PEEK).

While there is a lack of data concerning the effects of CFR-PEEK particles on human tissue, the effects of such wear debris in vitro and in animal studies is controversially discussed.

The aim of this study was to analyze human tissue containing CFR-PEEK as well as UHMWPE wear debris.

The authors hypothesized no difference between the used biomaterials because of similar size parameters of the wear particles in a prior knee simulator study of this implant.

Methods and Materials

Synovial tissue samples of 10 patients while knee revision surgery of a rotating hinge knee implant design (Enduro®, Aesculap, Germany) were achieved. The tibial inserts of this design were made from UHMWPE (GUR 1020), whereas the bushings and flanges are made of CFR-PEEK containing 30% polyacrylonitrile (PAN) based carbon fibers (PEEK-Optima LT1, Invibio Ltd. Thornton-Cleveleys, UK). In a prior in vitro test most of the released CFR-PEEK particles were in a size range between 0.1 and 2μm. The implant survival until revision surgery was 22 (2.5–48 min.-max.) months. As a control synovial tissue out of a patient also got knee revision surgery without any PEEK components.

The tissue was fixed with 4% paraformaldehyde, embedded in paraffin, sliced into 2 µm thick sections

stained with hematoxylin and eosin in a standard process. A modified panoptical staining (preincubation in propylenglycol; >3h; 35°C) was also done which stained the UHMWPE particles turquoise.

The study was approved by the ethics committee of the local university.

Introduction

Special high-flexion prosthetic designs show a small increase in postoperative flexion compared to standard designs and some papers show increased anterior knee pain with these prosthesis. However, no randomised controlled trails have been published which investigate difference in postoperative complaints of anterior knee pain. To assess difference in passive and active postoperative flexion and anterior knee pain we performed a randomized clinical trial including the two extremes of knee arthroplasty designs, being a high flex posterior stabilized rotating platform prosthesis versus a traditional cruciate retaining fixed bearing prosthesis. We hypothesised that the HF-PS design would allow more flexion, due to increased femoral rollback with less anterior knee pain than the CR design. We specifically assessed the following hypotheses:

Methods

In total 47 patients were randomly allocated to a standard cruciate retaining fixed bearing design (CR) in 23 patients and to a high-flexion posterior stabilized mobile bearing design (HF-PS) in 24 patients. Preoperative and one year postoperative we investigated active and passive maximal flexion. Furthermore, we used the VAS pain score at rest and during exercise and the Feller score to investigate anterior knee pain. A lateral roentgen photograph was used to measure femoral rollback during maximal flexion.

Background

Reasons for revision of metal-on-metal hip resurfacing arthroplasty (MoMHRA) have evolved with improving surgical experience and techniques. Early revisions were often due to fracture of the femoral neck while later revisions are associated with loosening and/or adverse local tissue reactions (ALTR) to wear debris. In some studies, revisions of MoMHRA with ALTR have been complicated by an increased risk of rerevision and poor outcome. The purpose of this study was to investigate the causes of failure and to identify factors that improve outcome following revision of a failed HRA.

Methods

From 2001 to May 2015, 180 consecutive HRA revisions were performed in 172 patients. Ninety-nine primary surgeries were done at a HRA specialist centre (99/4211, revision rate: 2.4%), 81 elsewhere. Eight different HRA designs were revised mainly in females (60%). Components’ orientation was measured from radiographs using EBRA. Ion levels were used as a diagnostic tool since 2006 (n=153). Harris-Hip-Score (HHS) was obtained prerevision and at latest follow-up. The initial experience of the first 42 cases (Initial Group) was compared to cases 43–180 (Later Group). Patients of the Later group were noted to have less soft tissue damage, had significantly bigger THA heads implanted at surgery, were educated of the increased complication risk and some wore an abduction brace for 6 weeks.

Background and aim

Since the market withdrawal of the ASR hip resurfacing in August 2010 because of a higher than expected revision rate as reported in the Australian Joint Replacement Registry (AOAJRR), metal-on-metal hip resurfacing arthroplasty (MoMHRA) has become a controversial procedure for hip replacement. Failures related to destructive adverse local tissue reactions to metal wear debris have further discredited MoMHRA. Longer term series from experienced resurfacing specialists however, demonstrated good outcomes with excellent 10-to-15-year survivorship in young and active men. These results have recently been confirmed for some MoMHRA designs in the AOAJRR. Besides, all hip replacement registries report significantly worse survivorship of total hip arthroplasty (THA) in patients under 50 compared to older ages. The aim of this study was to review MoMHRA survivorship from the national registries reporting on hip resurfacing and determine the risk factors for revision in the different registries.

Methods

The latest annual reports from the AOAJRR, the National Joint Registry of England and Wales (NJR), the Swedish Hip Registry (SHR), the Finnish Arthroplasty Registry, the New Zealand Joint Registry and the Arthroplasty Registry of the Emilia-Romagna Region in Italy (RIPO) were reviewed for 10-year survivorship of MoMHRA in general and specific designs in particular. Other registries did not have enough hip resurfacing data or long term data yet. The survivorship data were compared to conventional THA in comparable age groups and determinants for success/failure such as gender, age, diagnosis, implant design and size and surgical experience were reviewed.

Introduction

A total knee replacement is a proven cost-effective treatment for end-stage osteoarthritis, with a positive effect on pain and function. However, only 80% of the patients are satisfied after surgery. It is known that high preoperative expectations and residual postoperative pain are important determinants of satisfaction, but also malalignment, poor function and disturbed kinematics can be a cause. The purpose of this study was to investigate the correlation between the preoperative function and the postoperative patient reported outcomes PROMs) as well as the influence of the postoperative functional rehabilitation on the PROMs.

Methods

57 patients (mean 62,9j ± 10,6j), who suffer from knee osteoarthritis and who were scheduled for a total knee replacement at our centre, participated in this study. The range of motion of the knee, the muscle strength of the M. Quadriceps and the M. Hamstrings and the functional parameters (‘stair climbing test’ (SCT), ‘Sit to stand’ (STS) and ‘6 minutes walking test’ (6MWT)) were measured the night before surgery, ±6 months and ±1 year after surgery. This happened respectively with the use of a goniometer, HHD 2, stopwatch and the ‘DynaPort Hybrid’. Correlations between pre- and postoperative values were investigated. Secondly, a prediction was made about the influence of the preoperative parameters on on the subjective questionnaires (KOOS, OXFORD and KSS) as well as a linear and logistic regression.

Introduction

Better functional outcomes, lower pain and better stability have been reported with knee designs which restore physiological knee kinematics. Also the ability of the TKA design to properly restore the physiological femoral rollback during knee flexion, has shown to be correlated with better restoration of the flexor/extensor mechanism (appropriate flexor/extensor muscle lever arm, sufficient quadriceps force to extend the knee under load and limited patello-femoral force), which is fundamental to the function of the human knee. The purpose of the study is to compare the kinematics of three different TKA designs, by evaluating knee motion during Activities of Daily Living. The second goal is to see if there is a correlation between the TKA kinematics and the patient reported outcomes.

Methods

Ten patients who are at least 6 months after their Total Knee Replacement are included in this study. Seven satisfied and 3 dissatisfied patients are selected for this design. In this study 5 different movements are being analysed: flexion/extension; Sitting on and rising from a chair, Stair climbing, descending stairs, Flexion and extension open chain and squatting. These movements will be captured with a fluoroscope. The 2D images that are obtained, are matched with the 3D implants. (see figure 1 and 2.) This 3D image is processed with custom-made software to be able to analyse the movement (figure 3.). Tibio-femoral contactpoints of the medial and lateral condyles, tibio-femoral axial rotation, determination of the pivot-point are analysed and described. After this analysis, a correlation between the kinematics and the KOOS and KSS is investigated.

Introduction

Total hip arthroplasty (THA) is a commonly performed surgical procedure for the treatment of hip arthritis. Approximately 50,000 THAs are performed annually in Canada. The costs incurred to the healthcare system are tremendous, amounting to anywhere between 4.3 and 7.3 billion dollars each year. Despite the substantial financial burden of THA to the Canadian healthcare system, few studies have provided accurate cost estimations of this procedure.

Purpose

To determine the impact of surgical approach on costs of THA from a hospital perspective, and provide an updated cost estimation of THA within a publically funded healthcare system.

Conclusion

Significant difference in knee kinematics between squatting and cycling indicates the importance of testing a variety of conditions. Furthermore, this reveals the need to study clinically relevant motion patterns, selected from patient reported outcomes.

Conclusion

Design and evaluation of new knee simulator that allows synchronous studying of the knee kinematics, contact loads and tensile forces, under neutral conditions and extreme varus/valgus moment or internal/external tibial torque.

Introduction

For the evaluation of new orthopaedic implants, cadaveric testing remains an attractive solution. However, prior to cadaveric testing, the performance of an implant can be evaluated using numerical simulations. These simulations can provide insight in the kinematics and contact forces associated with a specific implant design and/or positioning.

Methods

Both a two and three dimensional simulation model have been created using the AnyBody Modelling System (AMS). In the two dimensional model, the knee joint is represented by a hinge. Similarly, the ankle and hip joint are represented by a hinge joint and a variable amplitude quadriceps force is applied to a rigid bar connected to the tibia (Figure 1a). In line with this simulation model, a hinge model was created that could be mounted in the UGent knee simulator to evaluate the performance of the simulated model. The hinge model thereby performs a cyclic motion under varying quadriceps load while recording the ankle reaction forces.

In addition to the two dimensional model, a three dimensional model has been developed (Figure 1b). More specifically, a model is built of a sawbone leg holding a posterior stabilized single radius total knee implant. The physical sawbone model contains simplified medial and lateral collateral ligaments. In line with the boundary conditions of the UGent knee simulator, the simulated hip contains a single rotational degree of freedom and the ankle holds four degrees of freedom (three rotations, single translation). In the simulations, the knee is modelled using the force-dependent kinematics (FDK) method built in the AMS. This leaves the knee with six degrees of freedom that are controlled by the ligament tension in combination with the applied quadriceps load and shape of the implant. The physical sawbone model goes through five cycles in the UGent simulator using while recording the kinematics of the femur and tibia using a set of markers rigidly attached to the femur and tibia bone. The position of the implant with respect to the markers was evaluated by CT-scanning the sawbone model.

INTRODUCTION

Rotator cuff tears are common injuries which often require surgical repair. Unfortunately, repairs often fail [1] and improved repair strength is essential. P2 Porous titanium (DJO Surgical, Austin TX) has been shown to promote osseointegration [2,3] and subdermal integration [4]. However, the ability of P2Porous titanium to aid in supraspinatus tendon-to-bone repair has not been evaluated. Therefore, the purpose of this study was to investigate P2 implants used to augment supraspinatus tendon-to-bone repair in a rat model [5]. We hypothesized that supraspinatus tendon-to-bone repairs with P2 implants would allow for ingrowth and increased repair strength when compared to standard repair alone.

METHODS

Thirty-four adult male Sprague-Dawley rats were used (IACUC approved). Rats received bilateral supraspinatus detachment and repair with one limb receiving P2 implant. Animals were sacrificed at time 0 (n=3), 2 weeks (n=8), 4 weeks (n=9) and 12 weeks (n=14). Limbs were either dissected for histological and SEM analysis or mechanical testing as described previously [5]. Specimens for histology and SEM were embedded in PMMA for tissue-implant interface analysis. Specimens were first viewed in SEM under BSE to detect bony ingrowth, then stained with Sanderson's Rapid Bone Stain and viewed under transmitted and polarized light for tissue ingrowth. Comparisons were made using Student's t-tests with significance at p≤0.05.

Introduction

Hydroxyapatite and poly-L-lactide (HA/PLLA) composites are osteoconductive and biodegradable. They have already been used clinically to treat fractured bones by inducing osteosynthesis and serving as the bone filling material. During revision of total hip arthroplasty, we have grafted bone onto the bone defect and covered it with an HA/PLLA mesh instead of using a metal mesh on the non-load bearing portion of the cup (Figure 1). However, whether the interface between the HA/PLLA and the titanium alloy cup was stable remains unclear.

Objectives

The purpose of this study was to determine and compare the histological osteoconductivity and osteoinductivity of HA/PLLA and titanium alloy.

Introduction

While research has been carried out widely for sagital pelvic tilt, research reports for coronal pelvic obliquity are few. The aim of this study is to evaluate changes of the pelvic obliquity before and after total hip arthroplasty.

Material and Methods

This retrospective study includes 146 cases of hips that were received total hip arthroplasty. There were 20 cases of revision, and 2 cases of re-revision. 17 cases were received bilateral total hip arthroplasty. The standing plain X-ray was used for evaluation of the pelvic obliquity in both before and 1-year after surgery. The correlation of pelvic obliquity was assessed between before and after surgery. 146 cases were classified into 3 groups (A, B, and C) according to the severity of the pelvic obliquity (0º−3º, 3º−6º, and >6º). Among the groups, statistical analysis was evaluated in the leg length discrepancy and the range of motion of the hip (flexion, extension, abduction, adduction, internal and external rotation) before and after surgery with 95% confidence intervals.

Background

Online video is increasingly becoming a key source for people to satisfy their information needs. YouTube is one of the post popular websites used for information exchange, with more than one billion unique visitors every month.

Questions/purposes

In an attempt to participate in personal health decisions related to hip arthritis, patients may access YouTube for further information. As YouTube is a non peer-reviewed platform and little is known about the quality of available videos. We therefore asked the following research questions: (1) What is the information quality of YouTube videos related to the diagnosis of hip arthritis and (2) what information for the treatment of hip arthritis can be found on YouTube?

Background

Though many advantages of reverse total shoulder arthroplasty (RTSA) have been demonstrated, a variety of complications indicate there is much to learn about how RTSA modifies normal shoulder function. This study assesses how RTSA affects deltoid muscle moment arms post-surgery using a subject-specific computational model driven by in vivo kinematic data.

Methods

A subject-specific 12 degree-of-freedom (DOF) musculoskeletal model was used to analyze the shoulders of 26 subjects (14 RTSA, 12 Normal). The model was modified from the work of Holzbaur et al. to directly input 6 DOF humerus and scapula kinematics obtained using fluoroscopy.

PURPOSE

Soft tissue balancing can be achieved by using spacer blocks, by distractors which measure tensile forces, or by instrumented devices which measure the forces on the lateral and medial condyles. However there is no quantitative method for assessment of balancing at clinical follow-up; to address this, we developed a Smart Knee Fixture (SKF) which measured the varus and valgus angles for a moment of 10 Nm. Our purpose was to determine if varus and valgus angles measured at clinical follow-up, was equivalent to the balancing parameters of distraction forces or contact forces measured at surgery. METHODS: The SKF, which measured VV angles using stretch sensors on each side of the knee, was validated by cadaver studies, fluoroscopy, and emg. The balancing parameters were:

A force analysis, and measurements on 101 surgical cases & clinical follow-up in an IRB study, were carried out to determine the relationship between these parameters.

RESULTS

The ratio TL/TM was approx. equal to FL/FM, especially near to a balanced state

The ratio MVAR/MVAL (lift-off moments) was equal to FL/FM

The ratio VAR/VAL was approx. equal to FL/FM only if the collateral stiffnesses were equal;

otherwise the ratio was approx. proportional to the collateral stiffnesses.

In the clinical follow-ups, there was no significant linear relation between VAR/VAL and FL/FM.

INTRODUCTION

The major loss of articular cartilage in medial osteoarthritis occurs in a central band on the distal femur, and in the center of the tibial plateau (Figure). This is consistent with varus deformity due to cartilage loss and meniscal degeneration, together with the sliding regions in walking. Treatment at an early stage such as KL grade 2 or 3, has the advantages of little bone deformity and cruciate preservation, and could be accomplished by resurfacing only the arthritic areas with Early Intervention (EI) components. Such components would need to be geometrically compatible with the surrounding bearing surfaces, to preserve continuity and stability. However because of the relatively small surface area covered, compared with total knees and even unicompartmentals, it is hypothesized that EI components will be an accurate fit on a population of knees with only a small number of sizes, and that accuracy can be maintained without requiring right-left components. We examined this hypothesis using unique design and methodology.

METHODS

Average femur and tibia models, including cartilage, were generated from MRI scans of 20 normal males. The images were imported into Geomagic software. Surface point clouds based on least squares algorithms produced the average models. Averages were also produced from different numbers to determine method validity. Average arthritic models were also generated from 12 KL 1–2 cases, and 13 KL 2–3 cases. The 3 averages were compared by deviation mapping. Using the average from the 20 knees, femoral and tibial implant surfaces were designed using contour matching to fit the arthritic regions, maintaining right-left symmetry. A 5 size system was designed corresponding to large male, average male, small male/large female, average female, small female. For the 20 knees, the components were fitted based on the best possible matching of the contours to the surrounding bearing surfaces. For the femoral component the target was 1 mm projection at the center, matching at the ends. The accuracy of reproducing the cartilage surfaces was then determined by mapping the deviations between the implant surfaces and the cartilage surfaces.

Introduction

The major function of the medial meniscus has been shown to be distribution of the load with reduction of cartilage stresses, while its role in AP stability has been found to be secondary. However several recent studies have shown that cartilage loss in OA occurs in the central region of the tibia while the meniscus is displaced medially. In a lab study (Arno, Hadley 2013) it was confirmed that the AP laxity was greatly reduced with a compressive force across the knee, while the femur shifted posteriorly and the AP laxity was increased after a partial meniscetomy of the posterior horn. It is therefore possible that under load, the compression of the meniscus and the cartilage, 2–3mm in total, allows load transmission on the central tibial plateau, and causes radial expansion and tension of the meniscus providing restraint to femoral displacements. This leads to our hypotheses that the highest loading on the medial meniscus would be at the extremes of motion, rather than in the mid-range, and that the meniscus would provide the majority of the restraint to anterior-posterior femoral displacements throughout flexion when compressive loads were acting.

Methods & Materials

MRI scans were taken of ten knee specimens to verify the absence of pathology and produce computer models. The knees were loaded in combinations of compressive and shear loading over a full flexion range. Tekscan sensors were used to measure the pressure distribution across the joint as the knee was flexed continuously. A digital camera was used to track the motion, from which femoral-tibial contacts were determined by computer modelling. Load transmission was determined from the Tekscan for the anterior horn, central body, posterior horn, and the uncovered cartilage in the center of the meniscus. An analysis was carried out (Fig 2) to determine the net anterior or posterior shear force carried by the meniscus.

PURPOSE

Soft tissue balancing can be achieved by using spacer blocks, by distractors which measure tensile forces, or by instrumented devices which measure the forces on the lateral and medial condyles. However there is no quantitative method for assessment of balancing at clinical follow-up; to address this, we developed a Smart Knee Fixture (SKF) which measured the varus and valgus angles for a moment of 10 Nm. Our purpose was to determine if varus and valgus angles measured at clinical follow-up, was equivalent to the balancing parameters of distraction forces or contact forces measured at surgery.

METHODS

The SKF, which measured VV angles using stretch sensors on each side of the knee, was validated by cadaver studies, fluoroscopy, and emg. The balancing parameters were:

A force analysis, and measurements on 101 surgical cases & clinical follow-up in an IRB study, were carried out to determine the relationship between these parameters.

Background

Scapular notching causes glenoid bone loss after a reverse total shoulder arthroplasty (rTSA). The goal of this study was to assess the influence of prosthesis design on notching.

Methods

Prospective, single surgeon cohort. Two different rTSA designs were consecutively implanted and compared: 25 Delta III rTSAs and 57 Delta Xtend rTSAs in 80 patients. Notching (Nerot 0–4) was assessed at 24 months follow-up. Patient dependent variables, surgical technique and implant geometry were assessed. Multivariate binary logistic regression was used to select the strongest independent predictors of notching.

Introduction

Bone marrow stimulation has been a successful treatment option in cartilage repair and microfracture was the procedure of choice since the late 1980s. Despite its success in young and active patients, microfracture has inherent shortcomings such as shallow channels, wall compression, and non-standardized depth and diameter. This in vitro study assessed bone marrow access comparing microfracture, 1 and 2mm K-Wires, 1mm drill, and a recently introduced standardized subchondral bone needling procedure (Nanofracture) that creates 9mm deep and 1mm wide channels.

Methods

An adult ovine model was used to assess access to bone the marrow spaces as well as effects on bone following microfracture, nanofracture, K-wire, and drilling following ethical clearance. All bone marrow stimulation techniques were conducted on a full thickness articular cartilage defect on the medial femoral condyles by the same surgeon. The same groups were repeated in vitro in 4 paired ovine distal femurs. MicroCT (Inveon Scanner, Siemens, Germany) was performed using 3D reconstruction and 25 micron slice analysis (MIMICS, Materialise, Belgium).

Introduction

Osteloysis following metal-on-UHMW polyethylene Total Hip Arthroplasty (THA) is well reported, as is lack of osteolysis following Ceramic-on-Ceramic (CoC)THA. Early ceramic failures did report some osteolysis, but in flawed implants. As 3rd and now 4th generation ceramic THAs come into mid- and long-term use, the orthopaedic community has begun to see reports of high survival rates and very low incidence of osteolysis in these bearings. Osteolysis reported after 3rd generation CoC THA often included metallosis due to neck rim impingement. In our department we have revised only 2 hips in over 6000 CoC THAs for osteolysis. Both had evidence of metallosis as well as ceramic wear. The technique used by Radiologists for identifying the nature of lesions on CT is the Hounsfield score which will identify the density of the tissue within the lucent area. It is common for radiologist to have no access to previous imaging, especially pre-operative imaging if a long time has elapsed.

With such a low incidence of osteolysis in this patient group, what, then, should a surgeon do on receiving a CT report on a ceramic-on-ceramic THA which states there is osteolysis? Revision of such implants in elderly patients has a high risk of morbidity and mortality.

Objectives

This retrospective review aims to determine the accuracy of CT in identifying true osteolysis in a cohort of long-term third generation ceramic-on-ceramic uncemented hip arthroplasties in our department.

Introduction

There is increasing interest in the functional positions the pelvis assumes with activities of daily living and its effect on acetabular cup orientation. A number of systems are commercially available to assess these movements, and attempt to position the acetabular component of a total hip replacement in a patient specific safe zone.

However, these functional positions are assessed pre operatively when the patient still has the arthritis which may affect the range of movement of the hips, and thus affect the functional position of the pelvis. Obviously the planned acetabular position must take into account any changes in the functional movement of the pelvis as a result of the surgery.

Ishida et al showed that a pelvis with more than a 10° anterior tilt when standing can be expected to correct towards neutral by 12 months post-surgery. However many of Ishida's cases were dysplastic. Hip arthritis in the Caucasian population is far less likely due to dysplasia and this may affect these pelvic tilt changes post-operatively.

Methods

120 patients who underwent total hip replacement by two surgeons through a posterior approach had had their acetabular planning based on functional imaging according to the Optimized Ortho Protocol (Optimized Ortho, Sydney Australia). They were re-assessed at 12 months post-surgery to determine the changes in their functional pelvic tilts. The Optimized Ortho protocol includes lateral radiographs with the patient standing, sitting forward about to lift off a seat, stepping up with the contralateral leg and a limited supine CT. The functional views are designed to display common functional activities.

Purpose

Factors influencing flexion angle of the knee before and after PS-TKA were assessed.

Methods

In 368 PS-TKA cases (71 males and 297 females) by means of modified gap control technique with Stryker NRG system, multi-variance analysis was performed to assess factors influencing flexion angle before TKA and flexion angle 3 weeks after TKA. Their mean age was 74.1 years old. Operative techniques and angle of the components were included as the factors.

Introduction

Porous scaffolds for bone ingrowth have numerous applications, including correcting deformities in the foot and ankle. Various materials and shapes may be selected for bridging an osteotomy in a corrective procedure. This research explores the performance of commercially pure Titanium (CPTi) and Tantalum (Ta) porous scaffold materials for use in foot and ankle applications under simplified compression loading.

Methods

Finite element analysis was performed to evaluate von Mises stress in 3 porous implant designs: 1) a CPTi foot and ankle implant (Fig 1) 2) a similar Ta implant (wedge angle = 5°) and 3) a similar Ta implant with an increased wedge angle of 20°. Properties were assigned per reported material and density specifications. Clinically relevant axial compressive load of 2.5X BW (2154 N) was applied through fixtures which conform to ASTM F2077–11.

Compressive yield and fatigue strength was evaluated per ASTM F2077–11 to compare CPTi performance in design 1 to the Ta performance of design 3.

Introduction

Comprehensive research and retrieval analyses of metal on metal / metal on polyethylene hip fretting and corrosion have been reported. Design choices such as modularity, material couples, geometry and offsets, as well as surgical variability and patient sensitivity have been cited as factors contributing to revision. Findings are informing new designs, surgical techniques and patient testing. However, similar efforts have not been performed on the shoulder. Do reduced joint reaction forces imply lower risk of fretting and corrosion? In this study we designed an accelerated corrosion fatigue (ACF) test specific for the shoulder to allow for evaluation of varying designs, and compared results to a reported shoulder retrieval study [Day ORS 2015].

Methods

Anatomic configuration and reverse shoulder ACF tests were developed with loads and orientations determined from instrumented shoulder data and reported literature. Scaled loads of 1480 N and 962 N were applied to anatomic (Fig 1.A) and reverse (Fig 1.B) prostheses, respectively (n=5 each, with additional assembly control), in potential worse case loading directions (α=25°, β=20°: anatomic; α=0°, β=0°: reverse), at 5 Hz for 3.0 Mc with R=0.1. Test environment included 0.9% NaCl solution at elevated temperature (50° C) and a decreased pH (3.5). Mass, roughness (Ra) and taper damage (modified Goldberg scoring system) measures were taken before and after testing. Taper connections were assembled at impact loads of 3600 N +/− 20% based on cadaveric studies. Goldberg scores for 79 humeral heads and 61 stems from an IRB approved collection served as the comparator.

Introduction

Two principal targets are dominating the spectrum of goals in total knee arthroplasty: first of all the orthopedic surgeon aims at achieving an optimal pain-free postoperative kinematic motion close to the individual physiologic range of the individual patient and secondly he aims for a concurrent high ligament stability within the entire range of movement in order to establish stability for all activities of daily living. This study presents a modified surgical procedure for total knee replacement which is ligament-controlled in order to put both component into the “ligamentous frame” of the patients individual kinematics.

Methods

The posterior femero-condylar index (PFC-I) is defined as being the posterior condylar offset divided by the distal antero-posterior diameter on a lateral radiograph. After careful preoperative planning the positions and orientations of the osteotomies is controlled intraoperatively via ligamentous guidance. Anterior and distal femoral osteotomy are planned on antero-posterior and lateral radiographs considering intramedular and mechanical axes as well as the orientation of the posterior condyles. Osteotomies are carried out in a stepwise fashion, starting with the anterior femoral osteotomy followed by the distal femoral osteotomy as planned. Then the extension gap is finalized by tensioning the ligaments and “top-down” referencing the level of the tibial osteotomy. After rotating the femur into the 90°-flexion position the flexion gap is finalized by referencing the level of the posterior condyle osteotomy in a “bottom-up” fashion to the tibial osteotomy. Hence, this technique determines the size of the femoral component with the last osteotomy. It likewise respects the new, ACL-lacking ligamentous framework and it drives the prosthetic components to fit into the new ligamentous envelope to follow the modified kinematics.

Introduction

Dislocation due to suboptimal cup positioning is a devastating complication in the early phase after total hip arthroplasty. Malpositioning can also result in other mechanical complications like subluxation, edge loading, increased debris, surface damage or squeaking in ceramic-on-ceramic hips. Preventing at least some of these complications in younger and more active patients is of paramount interest for the individual patient and for the society since optimized component orientation is an important determinant to reduce such risks and to further increase longevity of the implant. This study reports on two new surgical instruments that help the orthopedic surgeon to manually place both components within the optimized combined safe-zone (cSafe-Zone).

Material and Methods

More than 900 minimal-invasive total hip arthroplasties (MIS-THA) have been performed between 2007 and 2015 in our institution using the minimal-invasive direct anterior approach (DAA) on an orthopedic table with foot holder. Cups were implanted applying the “stem-first” surgical technique i.e. the prosthetic stem dictates the orientation of the socket depending on the prosthesis design. A system-specific trial head which indicates the prosthesis-specific relative orientation of cup and stem and a modified cup impactor were used to finally seat the definitive acetabular socket manually during trial stem reduction while fully visually controlling the optimal orientation of the cup during impaction. This surgical technique drives both components into their optimal relative positions according to the combined version and the combined safe-zone concept in total hip arthroplasty.

Methods

Forty-five patients undergoing elective primary Total Knee Arthroplasty (TKA) with were randomized into one of three groups in a double blind proof of concept study.

Study arm 1 received local infiltration analgesia ropivacaine intra-operatively, an elastomeric device of ropivacaine for 24 hours post-op.

Study arm 2 received a femoral nerve block of ropivacaine with placebo local infiltration analgesia and placebo intrathecal morphine.

Study arm 3 received intrathecal morphine, placebo femoral nerve block and placebo local infiltration analgesia. All patients received standardized pre-operative, intraoperative and Post-operative analgesic medication.

Participants were mobilized at 4 hrs, 24hrs and 48 hrs post operation. Range of Motion, Visual Analogue Scale (VAS) pain intensity scores and two minute walk test and Timed Up and Go test were performed. Postoperative use of analgesic drugs was recorded. Knee Society Score (KSS), Oxford Knee Score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were completed at preoperative and 6 weeks post op.

Results

Preliminary results of 32 participants convey the positive outcomes after total knee replacement demonstrated by the improvement in Oxford Knee Score and Knee Osteoarthritis Outcome score. There are marked improvements in the 2-minute walk tests at the six week time-point. At day one post-operative only 5 participants were unable to walk. Patient-controlled analgesia was used on 5 occasions on day one, 2 of which continued on day two. Sedation scores were recorded in six participants on day one and 2 on day two. Nausea was reported in 5 cases on day one and 9 on day two. Urinary catheter was needed in 5 cases on day one.

Importantly the study remains blinded, therefore an analysis of the three study arms is not available and is therefore currently difficult to report on the statistical significance. There will be further assessment of the efficacy of analgesia using VAS pain scores, analgesia consumption and side effects collected preoperatively, 0–24hrs and 24–48 hours postoperatively between the three randomized groups. The assessment of functional outcomes will be measured between the three groups by comparing the ability to mobilize the first 4 hrs after surgery, maximal flexion and extension, two minute walk test and timed up-and-go preoperatively, on postoperative day 1 and 2 and 6 weeks.

Introduction

Patients undergoing total knee arthroplasty have expected blood loss during and after surgery. The current literature remains inconclusive in regards to which surgical instrumentation techniques in total knee arthroplasty are effective in minimising peri-operative blood loss. The primary objective of this retrospective review of a prospective randomized cohort study is to compare surgical and patient factors and their influence on blood loss and transfusions rates between one type of Patient Specific Instrumentation (PSI) (SignatureTM), Navigated Computer-Assisted Surgery (CAS) and Conventional Total Knee Arthroplasty (TKA) surgical techniques.

Method

128 matched patients (38 SignatureTM, 44 CAS, 46 Conventional surgeries) were compared. Pre-operative factors were analysed including; age, gender, Body Mass Index (BMI), pre-operative hemoglobin (g/L), International Normalized Ratio (INR), use of anticoagulants and co-morbid bleeding diathesis. Maximal hemoglobin drop were compared on Day 1 to 3, as well as, transfusion requirement. Peri-operative factors were collected including; surgical time, tourniquet time, drain output, insitu drain time, order of tibia or femoral cut and intra-operative loss from suction.

Introduction

Traditional applied loading of the knee joint in experimental testing of RTKR components is usually confined to replicating the tibiofemoral joint alone. The second joint in the knee, the patellofemoral joint, can experience forces of up to 9.7 times body weight during normal daily living activities (Schindler and Scott 2011). It follows that with such high forces being transferred, particularly in high flexion situations such as stair climbing, it may be important to also represent the patellofemoral joint in all knee component testing.

This research aimed to assess the inclusion of the patellofemoral joint during in vitro testing of RTKR components by comparing tibial strain distribution in two experimental rigs. The first rig included the traditional tibiofemoral joint loading design. The second rig incorporated a combination of both joints to more accurately replicate physiological loading. Five implanted tibia specimens were tested on both rigs following the application of strain gauge rosettes to provide cortical strain data through the bone as an indication of the load transfer pattern. This investigation aimed to highlight the importance of the applied loading technique for pre-clinical testing and research of knee replacement components to guide future design and improve patient outcomes.

Methods

Five composite tibias (4th Generation Sawbones) were prepared with strain gauge rosettes (HBM), correctly aligned and potted using guides for repeatability across specimens. The tibias were then implanted with Stryker Triathlon components according to surgical protocol.

The first experimental rig was developed to replicate traditional knee loading conditions through the tibiofemoral joint in isolation. The second experimental rig produced an innovative method of replicating a combination of the tibiofemoral and patellofemoral joint loading scenarios. Both rigs were used to assess the load distribution through the tibia using the same tibia specimens and test parameters for comparison integrity (Figure 1). The cortical strains were recorded under an equivalent 500 N cyclical load applied at 10° of flexion by a hydraulic test machine.

Introduction

Highly crosslinked ultrahigh-molecular-weight polyethylene (XLPE) reduces wear and osteolysis in total hip arthroplasty, but it is unclear if XLPE will provide the same clinical benefit in total knee arthroplasty (TKA). Adhesive and abrasive wear generally dominate in polyethylene acetabular components, whereas fatigue wear is an important wear mechanism in polyethylene TKA tibial inserts. The wear resistance of XLPE depends on the crosslink density of the material, which may decrease during in vivo mechanical loading, leading to more wear and increased oxidation. To examine this possibility, we measured crosslink density and oxidation levels in loaded and unloaded locations of retrieved tibial inserts to evaluate the short-term performance of XLPE material in TKA.

Materials and Methods

Forty retrieved XLPE tibial inserts (23 remelted, 17 annealed) retrieved after a mean time of 18 ± 14 months were visibly inspected to identify loaded (burnished) and unloaded (unburnished) locations on the plateaus of each insert using a previously published damage mapping method. For each insert, four cubes (3 mm3) were cut from loaded and unloaded surface and subsurface locations (Fig. 1). Swell ratio testing was done according to ASTM F2214 to calculate crosslink density of the cubes. With a microtome, 200 μm sections were taken adjacent to the cubes and oxidation was assessed with Fourier transform infrared spectroscopy following ASTM F2102 (Fig. 2). Surface oxidation was measured in the sections adjacent the surface cubes and subsurface oxidation was measured in sections adjacent to the subsurface cubes. The effects of location (surface vs. subsurface in the loaded and unloaded regions) and thermal treatment (annealed vs. remelted) on crosslink density and oxidation were assessed with repeated measures generalized estimating equations (GEEs), with the implant treated as the repeated factor. Results are presented as means and 95% confidence intervals and the level of significance was α=0.05.

Introduction

Medial unicompartmental knee arthroplasty (UKA) restores mechanical alignment and reduces lateral subluxation of the tibia. However, medial compartment translation remains abnormal compared to the native knee in mid-flexion Intra-operative adjustment of implant thickness can modulate ligament tension and may improve knee kinematics. However, the relationship between insert thickness, ligament loads, and knee kinematics is not well understood. Therefore, we used a computational model to assess the sensitivity of knee kinematics, and cruciate and collateral ligament forces to tibial component thickness with fixed bearing medial UKA.

Methods

A computational model of the knee with subject-specific bone geometries, articular cartilage, and menisci was developed using multibody dynamics software (Fig 1a). The ligaments were represented with multiple non-linear, tension-only force elements, and incorporated mean structural properties. The 3D geometries of the femoral and tibial components of the Stryker Triathlon fixed-bearing UKA were captured using a laser scanner. An arthroplasty surgeon aligned the femoral and tibial components to the articular surfaces within the model (Fig 1b). The intact and UKA models were passively flexed from 0 to 90° under a 10 N compressive load. The tibial polyethylene insert was modeled by the orthopaedic surgeon to create a “balanced” knee. The modeled polyethylene insert thickness was then increased by 2 mm and decreased 2mm (in increments of 1mm) to simulate over- and under-stuffing, respectively. Outcomes were anterior-posterior (AP) translation of the femur on the tibia in the medial compartment, and forces seen by the ACL and MCL during mid-flexion (from 30 to 60° flexion). The mean differences between the intact knee model and all other experimental conditions for each outcome were calculated across mid-flexion.

Introduction

We developed original KKS non-cement THA system and used clinically over 10 years. KKS means Keio Kyocera Series. This system was developed co-ordinating with Keio-University and Kyocera Company in Japan. Our concept was to make original THA system suitable for Japanese people. Osteoarthritis of the hip in Japanese people caused mainly from developmental dysplasia of the hip. So the shape of femoral medullary canal is characteristic compared with foreign patients. We analyzed the femoral medullary canal shape in typical Japanese osteoarthritis 50 cases of the hip by the use of CT scan. From the results of these analyses, we determined the optimal shape of KKS non-cement stem for Japanese patients. It has double tapered shape in distal stem shaft. Proximal taper angle of the stem is 4 degree, and distal one is 3 degree. The proximal part of stem has characteristic notch in anterior and posterior and lateral surface to tolerate rotational stability.

Objectives

We evaluated long terms results (over 10 years) of KKS original stem mainly radio graphically and estimate the usefulness.

Purpose

Instability following total hip arthroplasty (THA) is an unfortunately frequent and serious problem that requires through evaluation and preoperative planning before surgical intervention. Prevention through optimal index surgery is of great importance, as the management of an unstable THA is challenging even for an experienced joints surgeon. However, even after well-planned surgery, a significant incidence of recurrent instability still exists. As you know Sir John Charnley is one of the first orthopaedic surgeons to address the issue of soft-tissue tensioning (STT) in the THA. Moreover leg-length discrepancy (LLD) after THA can pose a substantial problem for the orthopaedic surgeon. Such discrepancy has been associated with complications including nerve palsy, low back pain, and abnormal gait. The objective of this study is to assess hip instability of three different FOs in same patient undergoing THA during an operation.

Methods

We performed 70 patients who had undergone unilateral THA using CT based navigation system at a single institution for advanced osteoarthoritis from May 2013 to May 2014. We used postero-lateral approach in all patients. After cup and stem implantation, we assessed soft tissue tensioning in THA during operation. Trial necks were categorized into one of three groups: standard femoral offset (sFO), high femoral offset (hFO, +4mm compared to sFO) and extensive high femoral offset (ehFO, +8 mm compared to sFO). We measured distance of lift-off about each of three femoral necks using CT based navigation system and a force gauge with hip flexed at 0 degrees and 30 degrees under a traction of lower extremity. Traction force was 40% of body weight.

Introduction

As the aging society progresses rapidly, the number of patients underwent total knee arthroplasty (TKA) is increasing especially for the elderly population. In Japan, the average age for TKA is around 75 years old. Japanese Orthopaedic Association indicated a new clinical entity of musculoskeletal ambulation disability symptom complex (MADS) to define the higher risk of fall and ambulatory disability in the elderly population in 2006. The diagnosing criteria for MADS consists of 2 simple performance tests. 3m timed up and go test (TUG) evaluates ambulatory function, and one leg standing time (ST) assesses balancing ability.

Objective

In this study, we analyzed the effect of TKA on the ambulatory function by quantitative measurement using 2 simple performances test: TUG and ST.

Introduction

We have used CT-based navigation system for THA from 2004 (Fig, 1). The purpose is to set acetabular socket in optimal position. We have used two different matching methods in these navigation THA surgeries. The old one is Land-mark matching method (L-method), using conventional paired point matching procedure during surgery. The new one is CT-based fluoroscopy-matching system (F-method), that is new technology of image matching procedure before starting surgery (Fig. 2). We compared the accuracy of socket setting angle with these two systems and discuss the usefulness of navigation system.

Material

Materials were 477 THA patients using these navigation systems. 273 cases were with L method and 204 patients were with F method. The values between verification angle by navigation system during surgery and post-operative measured angle (by X-ray or CT scan) were calculated and compared.

Introduction

Cementless unicondylar knee implants are intended to offer surgeons the potential of a faster and less invasive surgery experience in comparison to cemented procedures. However, initial 8 week fixation with micromotion less than 150µm is crucial to their survivorship1 to avoid loosening2.

Methods

Test methods by Davignon et al3 for micromotion were used to assess fixation of the MAKO UKR Tritanium (MAKO) (Stryker, NJ) and the Oxford Cementless UKR (Biomet, IN). Data was analyzed to determine the activities of daily living (ADL) that generate the highest forces and displacements4, 5. Stair ascent with 3.2BW compressive posterior tibial load was identified to be an ADL which may cause the most micromotion5. Based on previous studies6, 10,000 cycles was set as the run-time. The AP and IE profiles were scaled back to 60% for the Oxford samples to prevent the congruent insert from dislocating. A four-axis test machine (MTS, MN) was used. The largest size UKRs were prepared per manufacturer's surgical technique. Baseplates were inserted into Sawbones (Pacific Research, WA) blocks1. Femoral components were cemented to arbors. The medial compartment was tested, and the lateral implants were attached to balance the loads.

Five tests were conducted for each implant with a new Sawbones and insert for each test per the test method3. The ARAMIS System (GOM, Germany) was used to measure relative motion between the baseplate and the Sawbones at three anteromedial locations (Fig. 1). Peak-Peak (P-P) micromotion was calculated in the compressive and A/P directions.

FEA studies replicating the most extreme static loading positions for MAKO micromotion were conducted to compare with the physical test results using ANSYS14.5 (ANSYS, PA).

Introduction

There have been many attempts to reduce the risk of femoral component loosening.

Using a tapered stem having a highly polished stem surface results in stem stabilization subsequent to debonding and stem-cement taper-lock and is consistent with force-closed fixation design.

Purpose

In this study, we assessed the subsidence of two different polished triple tapered stems and two different cements in primary THA.

Introduction

On the basis of a proposal by Noble, the marrow cavity form can be classified into three categories: normal, champagne-fluted and stovepipe. In the present study, three typical finite element femoral models were created using CT data based on Noble's three categories. The purpose was to identify the relationship of stress distribution of the surrounding areas between femoral bone marrow cavity form and hip stems. The results shed light on whether the distribution of the high-stress area reflects the stem design concept. In order to improve the results of THA, researchers need to consider the instability of a stem design based on the stress distributioin and give feedback on future stem selection.

Methods

As analyzing object, we selected SL-PLUS and BiCONTACT stems. To develop finite element models, two parts (cortical bone and stem) were constructed using four-node tetrahedral elements. The model consisted of about 60,000 elements. The material characteristics were defined by the combination of mass density, elastic coefficient, and Poisson's ratio. Concerning the analysis system, HP Z800 Workstation was used as hardware and LS-DYNA Ver. 971 as software. The distal end of the femur was constrained in all directions. On the basis of ISO 7206 Part 4,8 that specifies a method of endurance testing for joint prostheses, the stem was tilted 10°, and a 1500 N resultant force in the area around the hip joint was applied to the head at an angle of 25° with the long axis. Automatic contact with a consideration of slip was used.

Introduction

Mechanically aligned total knee arthroplasty(TKA) relies on restoring the hip-knee-ankle angle of the limb to neutral or as close to a straight line as possible. This principle is based on studies that suggest limb and knee alignment is related long term survival and wear. For that cause, there has been recent attention concerning computer-assisted TKA and robot is also one of the most helpful instruments for restoring neutral alignment as known. But many reported data have shown that 20% to 25% of patients with mechanically aligned TKA are dissatisfied. Accordingly, kinematically aligned TKA was implemented as an alternative alignment strategy with the goal of reducing prevalence of unexplained pain, stiffness, and instability and improving the rate of recovery, kinematics, and contact forces. So, we want to report our extremely early experience of robot-assisted TKA planned by kinematic method.

Materials and Methods

This study evaluated the very short term results (6 weeks follow up) after robot-assisted TKA aligned kinematically. 50 knees in 36 patients, who could be followed up more than 6 weeks after surgery from December 2014 to January 2015, were evaluated prospectively. The diagnosis was primary osteoarthritis in all cases. The operation was performed with ROBODOC (ISS Inc., CA, USA) along with the ORTHODOC (ISS Inc., CA, USA) planning computer. The cutting plan was made by single radius femoral component concept, each femoral condyles shape-matched method along the transverse axis using multi-channel CT and MRI to place the implant along the patient's premorbid joint line. Radiographic measurements were made from long bone scanograms. Clinical outcomes and motion were measured preoperatively and 6 weeks postoperatively.

Materials and Methods

This study was conducted with forty cases (20 cases of metal bipolar hemiarthroplasty (4 males, 16 females), 20 cases of ceramic bipolar hemiarthroplasty (2 males, 18 females)) from November 2012 to November 2014. Average age was 80.8±7.5 years for the metal bipolar group and 79.3±10.5 years for the ceramic bipolar group. We obtained motion pictures from standing position to maximum abduction in flexion by fluoroscopy then analyzed by 2D–3D image matching method. The motion range of the “Shell angle”, “Stem neck angle” and the “Stem neck and shell angle” has been compared between the metal bipolar group and the ceramic bipolar group (Fig. 1).

Results

Metal bipolar showed greater variability of the Stem neck angle and Shell angle than ceramic bipolar. Six of the twenty cases reached unilateral oscillation angle of 37 degrees in metal bipolar. In other words, 30% of metal bipolar group revealed neck-shell impingement. No case reached oscillation angle of 58 degrees in ceramic bipolar group. There was no significant difference between the metal bipolar group and the ceramic bipolar group with respect to the difference of minimum and maximum angle of Stem neck angle (movement range of the stem neck) and Shell angle (movement range of the bipolar cup). On the other hand, difference of minimum and maximum angle of the Stem neck and shell angle (movement range of the inner head) was significantly greater in the metal bipolar group than the ceramic bipolar group. Movement, range of bipolar shell was significantly greater than that of inner head in both groups (Table 1).

Introduction

Pelvic osteotomy such as Chiari osteotomy and rotational acetabular osteotomy (RAO) have been used successfully in patients with developmental dysplasia of the hip (DDH). However, some patients are forced to undergo total hip arthroplasty (THA) because of the progression of osteoarthritis. THA after pelvic osteotomy is thought to be more difficult because of altered anatomy of the pelvis. We compared six THAs done in dysplastic hips after previous pelvic osteotomy between 2008 and 2015 with a well-matched control group of 20 primary procedures done during the same period.

Materials and methods

Six THAs for DDH after previous Pelvic osteotomy (three Chiari osteotomies and three RAOs) were compared with 20 THAs for DDH without previous surgery. The patients were matched for age, sex, and BMI. Minimum follow-up for both groups of patients was one year (range, 12–79 months and 12–77 months, respectively). The average interval from pelvic osteotomy to total hip arthroplasty was 19.8 years (range 12–26 years). Clinical and Radiological evaluations were performed.

Background

Vancomycin and fosfomycin are antibiotic commonly used in Methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the efficacy of articulating cement spacer implegnated with vancomycin and articulating cement spacer implegnated with fosfomycin to inhibit MRSA.

Methods

Vancomycin implegnated articulating cement spacers and Fosfomycin implegnated articulating cement spacers were immersed in sterile phosphate buffered saline(PBS) and then incubated at 37 C. The samples were collected and change daily. Aliquots were tested for MRSA inhibition by disc diffusion method. The inhibition zones diameters were measured.

Background

Nutrient arteries appear as radiolucent lines (Fig. 1) on account of their topography and may erroneously suggest fracture lines.

Question/purpose

(1) How frequently the nutrient artery canals of the femur are seen after cementless THA and their distribution patterns are; (2) How to distinguish visible nutrient artery canal from fracture lines; and (3) Whether clinical significance of the nutrient artery canals of the femur in patients with primary cementless THA is evident or not.

Introduction

Modern prostheses of the 3rd and 4th generation facilitate a precise adjustment to various humeral anatomies. This provides major advantages regarding soft tissue balancing and the reconstruction of the rotational center. Thus, high expectations are linked to the use of modern shoulder prostheses compared to conventional designs.

Methods

Out of a prospective multicenter study, 108 cases (72 females, 36 males) were reviewed. All patients were treated with the same type of double eccentric shoulder prosthesis. The mean age at surgery was 71.5 years (range, 44.6 to 97.3). The Constant Score (CS), ASES Score, X-rays and complications were evaluated at 3, 6, 12 and 24 months as well as 4, 7 and 10 years follow-up.

Purpose

The success rate of surgical debridement and prostheses retention for acute periprosthetic joint infection (PJI) is controversial. This study aims to report our experience in managing acute PJI following total knee arthroplasty (TKA) with surgical debridement and prostheses retention, and to identify the prognostic factors that may influence the surgical outcomes.

Methods

A retrospective review from our prospective joint replacement register in Queen Mary Hospital, Hong Kong, of patients who were managed with surgical debridement and prosthesis retention for acute PJI after TKA between 1998 and 2013 was performed. The diagnosis of acute PJI was based on the 2011 Musculoskeletal Infection Society (MSIS) PJI diagnostic criteria. Both the early post-operative infections and the late haematogenous infections were included (Tsukayama type 2 and 3). Surgical outcomes were defined as successful if patients’ clinical symptoms had been relieved; inflammatory marker levels including C-Reactive Protein (CRP), Erythrocyte Sedimentation Rate (ESR) and White Blood Cell (WBC) count had returned to normal; X-rays showed no prosthetic loosening; and no lifelong antibiotic suppression was required. Outcomes were defined as failed if patients required any further surgeries (e.g., re-debridement, one or two-stage revision), or needed lifelong antibiotic suppression. All Patients’ perioperative data, i.e., age, primary diagnosis, pre-operative CRP, ESR, WBC, haemoglobin, albumin, glucose level, time lag from symptoms onset to debridement, synovial fluid total cell count and bacteriology were traced and recorded. SPSS 22.0 was used to calculate and compare the statistical differences between surgically successful group and failed group regarding the factors above.

Objective

Failures of internal fixation after intertrochanteric fractures pose great challenge to orthopaedic surgeons. Hip arthroplasty can be a remedy for such failures, however, the selection of femoral stem length is controversial. This study aims to report our experience of managing failed internal fixation after intertrochanteric fractures with standard femoral stem arthroplasty.

Methods

A retrospective review of patients who were managed with hip arthroplasty for failed internal fixation after intertrochanteric fractures in the First Affiliated Hospital of Fujian Medical University, P.R. China between January 2001 to December 2013 was performed. Patients’ age, gender, pre- and postoperative Harris Hip Score (HHS), femoral stem types and surgical outcomes were traced and analyzed.

Objective

Patient-specific instrumentation (PSI) is a novel technique in total knee arthroplasty (TKA) which potentially permits more accurate alignment of the components; however, there is no consensus in literature regarding the accuracy and reliability of PSI as many studies have shown controversial and inconsistent results of various PSI systems. A 24-month follow-up study was carried out to compare perioperative clinical outcomes, radiological limb alignment and component positioning, as well as functional outcomes following TKA between PSI and conventional instrumentation (CI).

Methods

During September 2011 and August 2012, 90 consecutive patients were scheduled to undergo unilateral TKA with either PSI or CI. TruMatch® Personalised Solutions was used in this study, and a senior surgeon performed all operations. Patients were clinically assessed before, 6-month and 24-month after surgery.

Objective

Computer-assisted minimally invasive total knee arthroplasty (CAMI-TKA) has gained increasing interest from orthopaedic surgeons due to its advantages in improving accuracy of component placement combined with benefits in postoperative recovery due to a smaller incision. However, long-term clinical and radiographic outcomes are lacking. The purpose of the present study is to compare the long-term radiographic features and functional outcomes between patients who underwent CAMI-TKA and those who underwent conventional TKA.

Methods

One hundred and eight patients who were randomized to undergo CAMI-TKA or conventional TKA during 2004 and 2005 were contacted by phone for a prospective follow-up review. Patients who have passed away or declined to participate in the study were excluded. Patients were asked to return to the hospital for clinical and functional assessments, long-leg and knee roentgenograms. Baseline characteristics were compared to account for potential confounders and multivariate statistical analysis applied to account for any differences in baseline characteristics.

INTRODUCTION

In native knees anterior cruciate ligament (ACL) and asymmetric shape of the tibial articular surface with a convex lateral plateau are responsible for differential medial and lateral femoral rollback. Contemporary ACL retaining total knee arthroplasty (TKA) improves knee function over ACL sacrificing (CR) TKA; however, these implants do not restore the asymmetric tibial articular geometry. This may explain why ACL retention addresses paradoxical anterior sliding seen in CR TKA, but does not fully restore medial pivot motion. To address this, an ACL retaining biomimetic implant, was designed by moving the femoral component through healthy in vivo kinematics obtained from bi-planar fluoroscopy and sequentially removing material from a tibial template. We hypothesized that the biomimetic articular surface together with ACL preservation would better restore activity dependent kinematics of normal knees, than ACL retention alone.

METHODS

Kinematic performance of the biomimetic BCR design (asymmetric tibia with convex lateral surface), a contemporary BCR implant (symmetric shallow dished tibia) and a contemporary CR implant (symmetric dished tibia) was analyzed using KneeSIM software. Chair-sit, deep knee bend, and walking were analyzed. Components were mounted on an average bone model created from magnetic resonance imaging (MRI) data of 40 normal knees. Soft-tissue insertions were defined on the average knee model based on MRI data, and mechanical properties were obtained from literature. Femoral condyle center motions relative to the tibia were tracked to compare different implant designs.

INTRODUCTION

In native knees the anterior cruciate ligament (ACL) plays a major role in joint stability and kinematics. Sacrificing the ACL in contemporary total knee arthroplasty (TKA) is known to cause abnormal knee motion, and reduced function. Hence, there is growing interest in the development of ACL retaining TKA implants. Accommodation of ACL insertion around the tibial eminence is a challenge with these designs. Therefore, a reproducible and practical test setup is necessary to characterize the strength of the ACL/bone construct in ACL retaining implants. Seminal work showed importance of loading the ACL along its anatomical orientation. However, prior setups designed for this purpose are complex and difficult to incorporate into a standardized test for wide adoption. The goal of this study was to develop a standardized and anatomically relevant test setup for repeatable strength assessment of ACL construct using basic force-displacement testing equipment.

METHODS

Cadaver knees were positioned with the ACL oriented along the loading axis and being the only connection between femur and tibia. 15° knee flexion was selected based on highest ACL tensions reported in literature. Therefore, the fixtures were adjusted accordingly to retain 15° knee flexion when the ACL was tensioned. The test protocol included 10 cycles of preconditioning between 6N and 60N at 1mm/s, followed by continuous distraction at 1mm/s until failure (Fig. 1). Eleven cadaveric knees (4 male, 7 female; 70.9 yrs +/−13.9 yrs) were tested using this setup to characterize a baseline ACL pullout strength (peak load to failure) in native knees.

INTRODUCTION

Mechanical tissue properties of some ligaments and tendons have been described in the literature. However, to our knowledge no data exists describing the tensile properties of the Iliopsoas tendon. The iliopsoas complex is in very close proximity to the hip joint running through the psoas notch from the inner side of the pelvis to the lesser trochanter on the posterior aspect of the proximal femur. The tendon muscle complex wraps around the anterior aspect of the femoral head. Hip joint intervention such as total hip arthroplasty (THA) can interfere with iliopsoas function and contact mechanics, and thereby play a major role in the clinically known condition of anterior hip pain. For computer simulations such as finite element analysis (FEA) precise knowledge of soft-tissue mechanical properties is crucial for accurate models and therefore, the goal of this study was to describe the iliopsoas tensile properties using uniaxial testing equipment.

METHODS

Ten iliopsoas tendons were harvested from five specimens (2 male, 3 female; 82.4 yrs ±7.4 yrs) and then carefully cleaned from any fat and muscle tissue. Two freeze clamps were fixed to each end of the tendon sample. The clamps were submerged in liquid nitrogen for 30 seconds to prevent tendon slip and attached to the test frame and load cell via carabiners allowing the tendon to rotate around its long axis. Width, thickness and initial gauge length of each tendon were measured before testing. The test protocol included 10 cycles of preconditioning between 6 N and 60 N at 0.4 mm/s, followed by continuous distraction at 0.4 mm/s until failure. For each tendon the linear stiffness was determined by fitting a straight line to the liner region on the force-displacement curve (Fig. 1).

Objective

To three-dimensionally reconstruct the proximal femur of DDH (Developmental dysplasia of the hip) and measure the related anatomic parameters, so that we could have a further understanding of the morphological variation of the proximal femur of DDH, which would help in the preoperative planning and prosthesis design specific for DDH.

Methods

From Jan.2012 to Dec.2014, 38 patients (47 hips) of DDH were admitted and 30 volunteers (30 hips) were selected as controls. All hips from both groups were examined by CT scan and radiographs. The Crowe classification method was applied. The CT data were imported into Mimics 17.0. The three-dimensional models of the proximal femur were then reconstructed, and the following parameters were measured: neck-shaft angle, neck length, offset, height of the centre of femoral head, height of the isthmus, height of greater trochanter, the medullary canal diameter of isthmus(Di), the medullary canal diameter 10mm above the apex of the lesser trochanter(DT+10), the medullary canal diameter 20mm below the apex of the lesser trochanter(DT-20), and then DT+10/Di, DT-20/Di and DT+10/DT-20 were calculated.

Introduction

Infection remains a serious complication following primary total hip arthroplasty (THA). Many factors including primary diagnosis, comorbidities and duration of procedure are known to influence the rate of infection. Although the association between patient and surgical factors is increasingly well understood, little is known about the role of the prosthesis. This analysis from the Australian Registry (AOANJRR) was undertaken to determine if revision for infection varied depending on the type of bearing surface used.

Methods

Three different bearing surfaces, ceramic on ceramic (CoC), ceramic on cross-linked polyethylene (CoXP) and metal on cross-linked polyethylene (MoXP) were compared. The study population included all primary THA undertaken for OA using these bearing surfaces and reported to the AOANJRR between 1999 and 2013. Kaplan-Meier survivorship curves were compiled with revision for infection as the end point. Hazard Ratios (HR) from Cox proportional hazards models were used to compare revision rates. Sub analysis examining the effect of age, gender, fixation of the femoral stem and femoral head size. To ensure there was no confounding due to differences in femoral and acetabular component selection a further analysis was undertaken which compared the three different bearings with the same stem and acetabular component combinations.