Aims

To evaluate mid-to long-term patient-reported outcome measures (PROMs) of endoprosthetic reconstruction after resection of malignant tumours arising around the knee, and to investigate the risk factors for unfavourable PROMs.

Accurate cup placement in total hip arthroplasty (THA) for the patients with developmental dysplasia of the hip (DDH) is one of the challenges due to distinctive bone deformity. Robotic-arm assisted system have been developed to improve the accuracy of implant placement. This study aimed to compare the accuracy of robotic-arm assisted (Robo-THA), CT-based navigated (Navi-THA), and manual (M-THA) cup position and orientation in THA for DDH.

A total of 285 patients (335 hips) including 202 M-THAs, 45 Navi-THAs, and 88 Robo-THA were analyzed. The choice of procedure followed the patient's preferences. Horizontal and vertical center of rotation (HCOR and VCOR) were measured for cup position, and radiographic inclination (RI) and anteversion (RA) were measured for cup orientation. The propensity score-matching was performed among three groups to compare the absolute error from the preoperative target position and angle.

Navi-THA showed significantly smaller absolute errors than M-THA in RI (3.6° and 5.4°) and RA (3.8° and 6.0°), however, there were no significant differences between them in HCOR (2.5 mm and 3.0 mm) or VCOR (2.2 mm and 2.6 mm). In contrast, Robo-THA showed significantly smaller absolute errors of cup position than both M-THA and Navi-THA (HCOR: 1.7 mm and 2.9 mm, vs. M-THA, 1.6 mm and 2.5 mm vs. Navi-THA, VCOR:1.7 mm and 2.4 mm, vs. M-THA, 1.4 mm and 2.2 mm vs. Navi-THA). Robo-THA also showed significantly smaller absolute errors of cup orientation than both M-THA and Navi-THA (RI: 1.4° and 5.7°, vs. M-THA, 1.5° and 3.6°, vs. Navi-THA, RA: 1.9° and 5.8° vs. M-THA, 2.1° and 3.8° vs. Navi-THA).

Robotic-arm assisted system showed more accurate cup position and orientation compared to manual and CT-based navigation in THA for DDH. CT-based navigation increased the accuracy of cup orientation compared to manual procedures, but not cup position.

Aims

Although periacetabular osteotomies are widely used for the treatment of symptomatic dysplastic hips, long-term surgical outcomes and patient-reported outcome measures (PROMs) are still unclear. Accordingly, we assessed hip survival and PROMs at 20 years after transpositional osteotomy of the acetabulum (TOA).

Although periacetabular osteotomies are widely used for the treatment of symptomatic acetabular dysplasia, the surgical outcomes after long term follow-up are still limited. Thus, we assessed hip survival and patient-reported outcomes (PROMs) at 20 years after the transposition osteotomy of acetabulum (TOA).

Among 260 hips in 238 patients treated with TOA, 172 hips in 160 patients were evaluated at average 20.8 years, excluding patients who died or lost to follow-up. Kaplan-Meier analysis was used to assess survivorship with an end-point of THA. PROMs were evaluated using the VAS satisfaction, VAS pain, Oxford hip score (OHS), and Forgotten joint score (FJS). The thresholds of favorable outcomes of FJS and OHS were obtained using the receiver-operating characteristic curve with VAS satisfaction ≥ 50 and VAS pain < 20 as anchors.

Thirty-three hips (19.2%) underwent THA at average 13.3 years after TOA. Kaplan-Meier analysis revealed hip survival rate at 20 years was 79.7%. Multivariate analysis showed the preoperative Tönnis grade significantly influenced hip survival. Survival rates with Tönnis grade 0, grade 1, and grade 2 were 93.3%, 86.7%, and 54.8% at 20 years, respectively. More than 60% of the patients showed favorable PROMs (VAS satisfaction ≥ 50, VAS pain < 20, OHS ≥ 42, FJS ≥ 51). Advanced Tönnis grade at the latest follow-up and higher BMI were significantly associated with unfavorable OHS, but not with other PROMs.

This study demonstrated the durability of TOA for hips with Tönnis grade 0–1 and favorable satisfaction in majority of the patients at 20 years after surgery. Current presence of advanced osteoarthritis is associated with the lower hip function (OHS), but not necessarily associated with subjective pain and satisfaction. Higher BMI also showed a negative impact on postoperative function.

Aims

This study aims to investigate the effects of posterior tibial slope (PTS) on knee kinematics involved in the post-cam mechanism in bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) using computer simulation.

Aims

Appropriate acetabular component placement has been proposed for prevention of postoperative dislocation in total hip arthroplasty (THA). Manual placements often cause outliers in spite of attempts to insert the component within the intended safe zone; therefore, some surgeons routinely evaluate intraoperative pelvic radiographs to exclude excessive acetabular component malposition. However, their evaluation is often ambiguous in case of the tilted or rotated pelvic position. The purpose of this study was to develop the computational analysis to digitalize the acetabular component orientation regardless of the pelvic tilt or rotation.

Regaining the walking ability is one of the main purposes of total knee arthroplasty (TKA). Improving the activities of daily living is a key of patient satisfaction after TKA. However, some patients do not gain enough improvement of ADL as they preoperatively expected, and thus are not satisfied with the surgery. The purpose of this study is to clarify the relationship between preoperative and postoperative physical functional status and whether preoperative scoring can predict the postoperative walking ability. Consecutive 136 patients who underwent total knee arthroplasty for osteoarthritis were prospectively assessed. The average age (±SD) was 74±7.7 and 74% of the patients was female. Berg Balance Scale (BBS) was assessed preoperatively and one year after the surgery. The time needed for 10m walking, muscle power for knee extension and flexion, visual analog scale (VAS) for pain in walking, and necessity of canes in walking were also assessed at one year after the surgery. Multivariate correlation analysis was performed for each parameter. Speaman rank correlation coefficient revealed that preoperative BBS was significantly correlated with the time needed for 10m walking (ρ=0.66, p<0.001). Logistic regression analysis also revealed that preoperative BBS is also correlated with the necessity for canes in walking one year after the surgery. The cut-off value of preoperative BBS for the necessity of canes in walking by ROC curve analysis was 48 points with 79% in sensitivity and 80% in specificity. The muscle powers were also weakly correlated with the walking ability at one year after the surgery, but VAS for pain was not. The study indicated that preoperative physical balance could predict the ability of walking one year after TKA regardless of the reduction of pain. It is suggested that surgery should be recommended before the physical balance function deteriorates to achieve the better walking ability after the TKA

Similar to the radiological findings in rapidly destructive arthrosis of the hip joint (RDA), subchondral insufficiency fracture of the femoral head (SIF) can result in progressive femoral head collapse of unknown etiology. We thus examined the osteoclast activity in hip joint fluid in SIF with progressive collapse in comparison to that in RDA. Twenty-nine hip joint fluid samples were obtained intraoperatively with whole femoral heads from 12 SIF patients and 17 RDA patients. SIF cases were classified into subgroups based on the presence of ≥2mm collapse on preoperative radiographs: SIF with progressive collapse (n=5) and SIF without progressive collapse (n=7). The levels of tartrate-resistant acid phosphatase (TRACP)-5b, interleukin-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 were measured. Numbers of multinuclear giant cells at the subchondral region were assessed histopathologically using mid-coronal slices of each femoral head specimen. Median levels of all markers and median numbers of multinuclear giant cells in SIF with progressive collapse were significantly higher than those in SIF without progressive collapse, while there were no significant differences in SIF with progressive collapse versus RDA. Regression analysis showed that the number of multinuclear giant cells correlated positively with the level of TRACP-5b in joint fluid. This study suggests an association of increased osteoclast activity with the existing condition of progressive collapse in SIF, which was quite similar to the findings in RDA. Therefore, high activation of osteoclast cell may reflect the condition of progressive collapse in SIF as well as RDA.

Osteonecrosis of the femoral head (ONFH) is an ischemic disorder that causes bone and bone marrow necrosis. In spite of many studies, the primary cause of ischemia is still unknown. The purpose of this study is to identify the susceptibility genes in ONFH.

We performed a genome-wide association study (GWAS) in 1,602 ONFH cases and 60,000 controls. Stratified GWASs based on the 3 subgroups of ONFH (corticosteroids, alcohol, idiopathic) were also performed. We then evaluated the candidate gene in silico using public databases.

Two loci in 12q24.11–12 and 20q12 showed significant association with ONFH. A stratified analysis suggested that the 12q24 locus was associated with ONFH through the drinking capacity. In the 20q12 locus, LINC01370 was the only gene, which functions were related to the plausible biological pathway for the development of ONFH.

A novel ONFH locus was identified at chromosome 20q12, and LINC01370 was the best candidate gene in this locus.

Introduction

CT-based navigation system in total hip arthroplasty (THA) is widely used to achieve accurate implant placement. Now, we developed our own CT-based navigation system originally, and since then we have been conducting various analysis in order to use the system more effectively. We compared the accuracy of registration with this navigation system and land mark matching type navigation system. In this study, we evaluated the influence of the surgical approach to the accuracy of registration.

Objectives

Osteophytes are products of active endochondral and intramembranous ossification, and therefore could theoretically provide significant efficacy as bone grafts. In this study, we compared the bone mineralisation effectiveness of osteophytes and cancellous bone, including their effects on secretion of growth factors and anabolic effects on osteoblasts.

Object

CT-based navigation system in total hip arthroplasty(THA) is widely used to achieve accurate implant placement. However, its internal structure was a trade secret. Therefore, it was hard to analyze optimal reference points. Now, we developed our own CT-based navigation system originally, and since then we have been conducting various analyses in order to use the system more effectively. The purpose of this study was to analyze the optimal area and the number of registration points, which enables to move initial errors into the acceptable range.

INTRODUCTION

Golf is considered low-impact sport, but concerns exist about whether golf swing can be performed in safe manner after THA. The purpose of this study was to clarify dynamic hip kinematics during golf swing after THA using image-matching techniques.

Introduction

Total knee arthroplasty (TKA) has achieved excellent clinical outcomes and functional performances. However, there is a need for greater implant longevity and higher flexion by younger and Asian patients. We determined the relationship between mobility and stability of TKA product because they are essential for much further functional upgrading. This research evaluated the geometry characteristics of femorotibial surfaces quantitatively by measuring their force of constraint by computer simulation and mechanical test.

Background

CT-based navigation system in total hip arthroplasty(THA) is widely used to achieve accurate implant placement. The purpose of this study was to evaluate the influence of initial error correction according to the differences in the shape of the acetabulum, and correction accuracy associated with operation approach after localization of registration points at anterior or posterior area of the acetabulum.

Bone remodeling effects is a significant issue in predicting long term stability of hip arthroplasty. It has been frequently observed around the femoral components especially with the implantation of prosthesis stem. Presence of the stiffer materials into the femur has altering the stress distribution and induces changes in the architecture of the bone. Phenomenon of bone resorption and bone thickening are the common reaction in total hip arthroplasty (THA) which leading to stem loosening and instability. The objectives of this study are (i) to develop inhomogeneous model of lower limbs with hip osteoarthritis and THA and (ii) to predict the bone resorption behavior of lower limbs for both cases.

Biomechanical evaluations of lower limbs are established using the finite element method in predicting bone remodeling process. Lower limbs CT-based data of 79 years old female with hip osteoarthritis (OA) are used in constructing three dimensional inhomogenous models. The FE model of lower limbs was consisted of sacrum, left and right ilium and both femur shaft. Bond between cartilage, acetabulum and femoral head, sacrum and ilium were assumed to be rigidly connected. The inhomogeneous material properties of the bone are determined from the Hounsfield unit of the CT image using commercial biomedical software. A load case of 60kg body weight was considered and fixed at the distal cut of femoral shaft. For THA lower limbs model, the left femur which suffering for hip OA was cut off and implanted with prosthesis stem. THA implant is designed to be Titanium alloy and Alumina for stem and femoral ball, respectively.

Distribution of young modulus of cross-sectional inhomogeneous model is presented in Fig. 2 while model of THA lower limbs also shown in Fig. 2. Higher values of young modulus at the outer part indicate hard or cortical bone. Prediction of bone resorption is discussed with the respect of bone mineral density (BMD). Changes in BMD at initial age to 5 years projection were simulated for hip OA and THA lower limbs models.

The results show different pattern of stress distribution and bone mineral density between hip OA lower limbs and THA lower limbs. Stress is defined to be dominant at prosthesis stem while femur experienced less stress and leading to bone resorption. Projection for 5 years follow up shows that the density around the greater tronchanter appears to decrease significantly.

Today's aging society is seeing an increase of patients with rheumatoid arthritis and osteoarthritis, as well as an increase in joint replacement surgery. The artificial joints used in this surgery frequently uses ultra-high molecular weight polyethylene (UHMWPE) as a bearing material. However, UHMWPE wear particles are considered to be a major factor in long-term osteolysis, and implant loosening. Many researchers have reported that the volume and size of particles are critical factors in macrophage activation, with particles in the size range of 0.1 – 1.0 μm being the most biologically active. The micro slurry-jet erosion (MSE) apparatus was introduced to minimize the amount of wear, and increase the size of UHMWPE wear particles by texturing the surfaces of Co-Cr-Mo alloy implants. The MSE apparatus uses a slurry of alumina particles (WA#8000: average diameter 1.2 μm) mixed with water. The slurry and compressed air are mixed within an injection nozzle, which is then applied to the Co-Cr-Mo alloy at high speed to achieve a desired nano-textured surface. In this study, four Co-Cr-Mo alloy surface profiles were prepared. The MSE injection nozzle was fed 40.0 mm in alternating directions across each surface with an orthogonal step of 0.5 mm. The surface M-1 was processed with an injection nozzle feed rate of 1.0 mm/s, and obtained a surface roughness of 5.7 nm. M-2 was processed with a feed rate of 2.0 mm/s, and had a surface roughness of 2.3 nm. The M-4 surface used a 40.0 mm alternating directions surface feed, but with a 1.0 mm orthogonal step, and an injection nozzle feed rate of 0.5 mm/s. It obtained a surface roughness of 4.0 nm. The G-1 surface, with a roughness of 10.0 nm, was processed with the typical lapping method, which is used in conventional artificial joints [Fig. 1]. A pin-on-disk wear tester, capable of multidirectional motion, was used to assess which surface was the most appropriate for artificial joints. The UHMWPE pins were flat ended cylinders, 12.0 mm in diameter, and were placed on the disk with a contact pressure of 6.0 MPa. Tests were carried out in 25% (v/v) fetal calf serum with sodium azide to retard bacterial growth. A sliding speed of 12.1 mm/s, and a total sliding distance of 15.0 km were applied. The wear weight of the MSE textured surface M-1 was significantly lower than the wear weight of the conventional surface. Moreover, the percentages of various wear particle sizes obtained from MSE surface texturing was significantly different from those obtained from the traditional surface.

Effectiveness and long term stability of hip resurfacing and total hip arthroplasty for osteoarthritis patients are still debated nowadays. Several clinical and biomechanical issues have to be considered, including pain relief, return to function, femoral neck fractures, impingement and prosthesis loosening. Normally, patients with hip arthroplasties are facing gait adaptation and at risk of fall. Sudden impact loading and twisting during sideway falls may lead to femoral fractures and joint failures. The purposes of this study are (i) to investigate the stress behavior of hip resurfacing and total hip arthroplasty, and (ii) to predict pattern of femoral fractures during sideway falls and twisting configurations.

Computed tomography (CT) based images of a 54-year old male were used in developing a 3D femoral model. The femur model was designed to be inhomogeneous material as defined by Hounsfield Unit of the CT images. CAD data of hip arthroplasties were imported and aligned to represent RHA and THA femur modelas shown in Fig.1. Prosthesis stem is modeled as Ti-6Al-4V material while femoral ball as Alumina properties. Meanwhile, RHA implant is assigned as Co-Cr-Mo material. Four types of loading and boundary conditions were assigned to demonstrate different falling (FC) and twisting (TC) configurations (see Fig.2). Finite element analysis combined with a damage mechanics model was then performed to predict bone fractures in both arthroplasty models. Different loading magnitudes up to 4BW were applied to extrapolate the fracture patterns.

Prediction of femoral fracture for RHA and THA femurs are discussed in corresponding to maximum principal stress and damage formation criterion. The load bearing strain was set to 3000micron, the physiological bone loading that leads to bone formation. The test strength was wet to 80% of the yield strength determined from the CT images. Different locations of fracture are predicted in each configuration due to different loading direction and boundary conditions as shown in Fig.3. For falling configurations, fractures were projected at trochanteric region for intact and RHA femur, while THA femurs experience fracture at inner proximal region of bone. Differs to twisting configurations, both arthroplasties were predicted to fracture at the distal end of femurs.

Introduction

3D-to-2D model registration technique has been used for evaluating 3D kinematics from 3D surface models of the prostheses or bones and radiographic image sequences. However, no studies have employed these techniques to evaluate in vivo hip kinematics under dynamic weight-bearing conditions. The purposes of this study were to evaluate kinematics of healthy hips and also hips with osteoarthritis (OA) prior to total hip arthroplasty (THA) during four different weight-bearing activities using 3D-to-2D model-to-image registration technique.

This study presents the use of precision surface machining on artificial joint bearing surfaces in order to inhibit macrophage activation. Ultra-high molecular weight polyethylene (UHMWPE) is widely used as a bearing material in polymer-on-hard joint prostheses. However, UHMWPE wear particles are considered to be a major factor in long-term osteolysis and implant loosening. Several studies report that wear particle size is a critical factor in macrophage activation, with particles in the size range of 0.1 – 1.0 μm being the most biological active. The surface for a conventional Co-Cr-Mo alloy joint implant generally has a 10.0 – 20.0 nm roughness. After precision machining, the Co-Cr-Mo alloy surface had a 1.0 – 2.0 nm roughness with scattered concave shapes up to 50 nm in depth. This precision surface machining method used a typical lapping method, but the relationship between the slurry and the machining surface was strictly controlled in order to emphasize the micro-erosion mechanism. A pin-on-disc wear tester capable of multidirectional motion was used to verify that the new surface was the most appropriate for joints. Tests were carried out in 25% (v/v) fetal calf serum with sodium azide to retard bacterial growth. UHMWPE pins, 12.0 mm in diameter with a mean molecular weight of 6.0 million, were placed on the Co-Cr-Mo alloy disc at a contact pressure of 6.0 MPa. A sliding speed of 12.1 mm/s, and a total sliding distance of 15.0 km were applied. The new surface reduced the amount of UHMWPE wear, which would ensure the long-term durability of joints. The new surface also enlarged the size of UHMWPE particles, but did not change their morphological aspect. Primary human peripheral blood mononuclear phagocytes were cultured with the particles. The wear particles generated on the new surface inhibited the production of IL-6, which indicates a reduction of induced tissue reaction and joint loosening.

Background:

Total knee arthroplasty (TKA) has achieved excellent clinical outcomes and functional performances. However, younger and Asian patients require even greater implant longevity and higher flexion. It is necessary for much further functional upgrading to design TKA with mobility and stability. Therefore, we determined the relationship between mobility and stability of TKA.

Introduction

The objective of this study was to verify the long-term outcome of transtrochanteric anterior rotational osteotomy (ARO) for osteonecrosis of the femoral head (ONFH) in young patients with systemic lupus erythematosus (SLE).

Introduction

Transtrochanteric curved varus osteotomy is one of the effective joint-preserving operations for osteonecrosis (ON) of the femoral head. We correlated various factors with the radiological outcome of this procedure.

Introduction

Subchondral insufficiency fracture of the femoral head (SIF) is a recently proposed concept. It is generally seen in elderly people, however, some young adults have also been reported to suffer from this fracture. The purpose of this study was to investigate the clinical results of a transtrochanteric anterior rotational osteotomy (ARO) performed in young adults with SIF.

Introduction

Subchondral insufficiency fracture of the femoral head (SIF) often occurs in osteoporotic elderly patients. Patients usually suffer from acute hip pain without any obvious antecedent trauma. Radiologically, a subchondral fracture is seen mainly in the superolateral portion of the femoral head. The T1-weighted magnetic resonance (MR) images show a low-intensity band in the subchondral area of the femoral head, which tends to be irregular, disconnected, and convex to the articular surface. This low-intensity band in SIF was histologically proven to correspond to the fracture line with associated repair tissue. Some cases of SIF resolve after conservative treatment, while others progress until collapse, thereby requiring surgical treatment. The prognosis of SIF remains unclear. This study investigated the risk factors that influence the prognosis of SIF based on the progression of the collapse.

Introduction

Subchondral insufficiency fracture (SIF) needs to be differentiated from osteonecrosis. The purpose of this study was to evaluate the imaging and histopathological findings of patients 60 years or older with radiological evidence of subchondral collapse of the femoral head.

Background

In Japan, idiopathic osteonecrosis of the femoral head (ONFH) is designated as a specified rare and intractable disease in patients for whom medical care is subsidized through the Specified Disease Treatment Research Program. Each patient is approved for the subsidy based upon a prefectural governmental review after filing an application together with a clinical research form documenting the patient's medical history, laboratory/clinical findings, and treatment. The purpose of this study was to conduct a fact-finding study of ONFH patients in the Fukuoka Prefecture based on clinical research forms of the Specified Disease Treatment Research Program.

Transposition osteotomy of the acetabulum (TOA) was the first periacetabular osteotomy for the osteoarthritis hips due to acetabular dysplasia, in which the acetabulum was transposed with articular cartilage. TOA improves coverage of the femoral head to restore congruity and stability, and also prevent further osteoarthritis deterioration and induce regeneration of the joint. Many good clinical outcomes have been reported for such periacetabular osteotomies for osteoarthritis of the hips at an early stage. In contrast, the clinical outcome is controversial for those hips at an advanced stage, in which the joint space has partly disappeared. The purpose of this study was to investigate whether TOA is an appropriate option for treatment of osteoarthritis of the hips at the advanced stage by comparing with matched control hips at the early stage.

Between 1998 and 2001, TOA was performed in 104 hips of 98 patients.

Sixteen of 17 hips (94%) with osteoarthritis at the advanced stage were examined and compared with 37 matched control hips at the early stage. The mean age at the operation was 48(38–56) and the mean follow-up period was 88 (65–107) months. TOA corrected the acetabular dysplasia and significantly improved containment of the femoral head.

No hips had secondary operations including THA. Clinical scores were also significantly improved in both of the groups. In the advanced osteoarthritis cases, there was a tendency for abduction congruity before transposition osteotomy of the acetabulum to reflect the clinical outcome.

TOA is a promising treatment option for the advanced osteoarthritis of the hips as well as for those patients at the early stage when preoperative radiographs show good congruity or containment of the joint.

ROBODOC is a well known tool for a computer assisted arthroplasty. However, the incision tends to enlarge with the system because of the restriction of range of motion. We have developed the robot system for minimally invasive arthroplasty. This report shows the accuracy of our system composed of original planning software, navigation and bone cutting robot.

We took the DICOM data of cadaver knees from computed tomography. The data were transferred to the workstation for planning. Matching points for registration and cutting planes were determined on the planning software. Cutting tool was the 6th robot which was able to recognize the locations of its apex and the cadaver knee with navigation system. We made five planes for TKA and two planes for UKA on femur. Then we made one plane on tibia. We evaluated the accuracy by measurement the location of cutting plane under navigation system and by CT data.

The registration errors of femur and tibia were less than 1.0mm about cadaver knees. The errors of cutting planes were 1.3 mm about the distal end of femur and 0.5 mm about the proximal end of tibia. The accuracies of the angles of cutting planes were 1.9 degrees and 0.8 degrees compared to the mechanical axis.

The errors of anterior and posterior plane of femur were increased compared to the distal plane. It was because the accuracy of registration were correct in axial direction but was not satisfied in rotational direction. The error was considered by the location of points which decided the rotation alignment. We will make effort to minimize the errors of registration and put it into practical use as soon as possible.

In order to clarify how intra-articular lesions influence the survival of a periacetabular osteotomy in patients with dysplasia of the hip, we performed an observational study of 121 patients (121 hips) who underwent a transposition osteotomy of the acetabulum combined with an arthroscopy. Their mean age was 40.2 years (13 to 64) and the mean follow-up was 9.9 years (2 to 18). Labral and cartilage degeneration tended to originate from the anterosuperior part of the acetabulum, followed by the femoral side. In all, eight hips (6.6%) had post-operative progression to Kellgren–Lawrence grade 4 changes, and these hips were associated with the following factors: moderate osteoarthritis, decreased width of the joint space, joint incongruity, and advanced intra-articular lesions (subchondral bone exposure in the cartilage and a full-thickness labral tear). Multivariate analysis indicated subchondral bone exposure on the femoral head as an independent risk factor for progression of osteoarthritis (p = 0.003). In hips with early stage osteoarthritis, femoral subchondral bone exposure was a risk factor for progression of the grade of osteoarthritis.

Although the outcome of transposition osteotomy of the acetabulum was satisfactory, post-operative progression of osteoarthritis occurred at a high rate in hips with advanced intra-articular lesions, particularly in those where the degenerative process had reached the point of femoral subchondral bone exposure.

The transfer of part of the ulnar nerve to the musculocutaneous nerve, first described by Oberlin, can restore flexion of the elbow following brachial plexus injury. In this study we evaluated the additional benefits and effectiveness of quantitative electrodiagnosis to select a donor fascicle. Eight patients who had undergone transfer of a simple fascicle of the ulnar nerve to the motor branch of the musculocutaneous nerve were evaluated. In two early patients electrodiagnosis had not been used. In the remaining six patients, however, all fascicles of the ulnar nerve were separated and electrodiagnosis was performed after stimulation with a commercially available electromyographic system. In these procedures, recording electrodes were placed in flexor carpi ulnaris and the first dorsal interosseous. A single fascicle in the flexor carpi ulnaris in which a high amplitude had been recorded was selected as a donor and transferred to the musculocutaneous nerve. In the two patients who had not undergone electrodiagnosis, the recovery of biceps proved insufficient for normal use. Conversely, in the six patients in whom quantitative electrodiagnosis was used, elbow flexion recovered to an M4 level.

Quantitative intra-operative electrodiagnosis is an effective method of selecting a favourable donor fascicle during the Oberlin procedure. Moreover, fascicles showing a high-amplitude in reading flexor carpi ulnaris are donor nerves that can restore normal elbow flexion without intrinsic loss.

In order to investigate the mechanisms of collapse in osteonecrosis of the femoral head, we examined which part of the femoral head was the key point of a collapse and whether a collapsed region was associated with the size of the necrotic lesion. Using 30 consecutive surgically removed femoral heads we retrospectively analysed whole serial cut sections, specimen photographs, specimen radiographs and histological sections.

In all of the femoral heads, collapse consistently involved a fracture at the lateral boundary of the necrotic lesion. Histologically, the fractures occurred at the junction between the thickened trabeculae of the reparative zone and the necrotic bone trabeculae. When the medial boundary of the necrotic lesion was located lateral to the fovea of the femoral head, 18 of 19 femoral heads collapsed in the subchondral region. By contrast, when the medial boundary was located medial to the fovea, collapse in the subchondral region was observed in four of 11 femoral heads (p = 0.0011). We found that collapse began at the lateral boundary of the necrotic lesion and that the size of the necrotic lesion seemed to contribute to its distribution.

We investigated the factors related to the radiological outcome of a transtrochanteric curved varus osteotomy in patients with osteonecrosis of the hip. We reviewed 73 hips in 62 patients with a mean follow-up of 12.4 years (5 to 31.1). There were 28 men and 34 women, with a mean age of 33.3 years (15 to 68) at the time of surgery. The 73 hips were divided into two groups according to their radiological findings: group 1 showed progression of collapse and/or joint-space narrowing; group 2 had neither progressive collapse nor joint-space narrowing. Both of these factors and the radiological outcomes were analysed by a stepwise discriminant analysis. A total of 12 hips were categorised as group 1 and 61 as group 2. Both the post-operative intact ratio and the localisation of the necrotic lesion correlated with the radiological outcome. The cut-off point of the postoperative intact ratio to prevent the progression of collapse was 33.6%, and the cut-off point to prevent both the progression of collapse and joint-space narrowing was 41.9%.

The results of this study indicate that a post-operative intact ratio of 33.0% is necessary if a satisfactory outcome is to be achieved after this varus osteotomy.

Combined anteversion (CA) is defined as the sum of the anteversions of acetabular and femoral components. In this study, we determined the appropriate CA in a variety of femoral versions using a total hip arthroplasty model. In addition, we also examined the usefulness of a changeable neck to improve range of hip motion in these cases.

Using a THA model, the range of motion (ROM) was tested in various CA values obtained by changing the anteversion of a cup in six increments after setting the femoral anteversion to 20° or 60° anteversion and 20° retroversion. The angle of the changeable neck was changed in 11 increments of 5°. To evaluate stability, the range of internal rotation at 90° flexion, the external rotation at 0° extension, and the range flexion was measured when any impingement occurred prior to dislocation. We defined the required ROM that met 40° internal rotation, 30° external rotation, and 110° flexion.

In normal 20° anteversion group, the required ROM was achieved with CA between 30° and 50° without using any changeable necks. In excessive anteversion 60° group, the range of external rotation was less than 10° even when the acetabular component was set 10° retroverted, because of the bone impingement between the greater trochanter and the posterior acetabulum. When 25° retroverted changeable neck was used, ROM improved to 30° external rotation and satisfied the required ROM. In 20° retroversion group, the internal rotation angle was 31° even when the acetabular component was opened 35° anteverted, because of anterior neck-liner impingement. When 25° anteverted changeable neck was used, ROM improved to 39° internal rotation and 130° flexion.

In cases with normal anteversions, the required ROM can be achived by adjusting CA. In cases with excessive anteversion or retroversion, there was a limitation of the CA adjustment. The use of changeable necks allows for further improvement of ROM by compensating femoral anteversions.

Treating Crowe type 3 or 4 of hips tends to be technically difficult when performing total hip arthroplasty (THA) due to the severely dysplastic acetabulum and proximal femur in addition to a high dislocation of the hip. Since the socket is limited to being placed at the original hip center, a femoral shortening osteotomy is often required in order to prevent neurovascular problems. This osteotomy will need the stability of the femoral stem with both the proximal and the distal femoral bones. We used the modular S-ROM stem, which has a valuable proximal structure and a distal flute structure to stabilize the stem with the proximal and distal femoral fragments. The purpose of this study was to report the clinical and radiographic results of the primary THA with a shortening osteotomy while also using the S-ROM prosthesis.

Between 1994 and 2004, primary THA using the S-ROM prosthesis was performed on 7 hips in 6 cases (1 male, 5 females). Crowe type 3 or 4 was observed in one and 6 hips, respectively. The mean age at operation was 56 years old (range 51~60). The mean follow-up period was 41 months (range 24~56 months). Four hips had previously undergone a subtrochanteric valgus osteotomy. All hips underwent a step-cut femoral osteotomy at the proximal metaphysis for the shortening and/or correction of angulations with on-lay chip bone grafts. All of the used stems were straight type. The clinical outcome was evaluated using the clinical scoring system of hip joints established by the Japanese Orthopaedic Association (JOA). According to a 100 point scale, pain was determined to be 40, ROM was 20, gait was 20 and ADL was 20.

No hips had undergone any revision surgery as of the most recent follow-up. Union was achieved at the osteotomy site in all hips. Neither osteolysis nor a loosening of the implant was radiographically observed. The mean JOA score before THA and at the last follow-up was 41 (31–48) and 81 (62–91) points, respectively. The mean postoperative days to start full weight bearing was 53 days (range 49~70). In two cases (28%), a procedure using circular wiring was performed to treat a crack in the proximal femur.

The S-ROM prosthesis was thus found to be useful for primary THA with a shortening metaphyseal femoral osteotomy for hips in patients with Crowe type 3 or 4 developmental dysplasia.

Transtrochanteric curved varus osteotomy was designed to avoid some of the disadvantages of varus wedge osteotomy, such as post-operative leg-length discrepancy. In this retrospective study we investigated the leg-length discrepancy and clinical outcome after transtrochanteric curved varus osteotomy undertaken in patients with osteonecrosis of the femoral head. Between January 1993 and March 2004, this osteotomy was performed in 42 hips of 36 patients with osteonecrosis of the femoral head. There were 15 males and 21 females with a mean age at surgery of 34 years (15 to 68). The mean follow-up was 5.9 years (2.0 to 12.5). The mean pre-operative Harris hip score was 64.0 (43 to 85) points, which improved to a mean of 88.7 (58 to 100) points at final follow-up. The mean varus angulation post-operatively was 25° (12° to 38°) and the post-operative mean leg-length discrepancy was 13 mm (4 to 25). The post-operative leg-length discrepancy showed a strong correlation with varus angulation (Pearson’s correlation coefficient; r = 0.9530, p < 0.0001), which may be useful for predicting the leg-length discrepancy which can occur even after transtrochanteric curved varus osteotomy.

Purpose: Osseointegration is crucial for favorable outcomes after total hip arthroplasty (THA) using cement-less femoral components. Osseointegration is recognized on radiographs as the endosteal spot weld, which is the bony bridge between the implant and surrounding bone (Engh et al, CORR, 1989). The purpose of this study is to evaluate the clinical and radiographic results for patients who had hydroxyapatite (HA)-coated rough surfaced implants compared with those who had identical implants without HA-coating at three-year minimum follow-up.

Methods: Ninety-one patients, one hundred and two hips who had primary THA with titanium arc sprayed rough surfaced femoral implants were retrospectively studied. Sixty-four hips had received HA-coated implants (HA) and 38 hips had an identical component but without HA (Non-HA). Radiographical parameters analyzed included 1) endosteal spot welds, 2) radiolucent lines, 3) calcar responses, 4) pedestal formation, 5) implant loosening, 6) endosteal osteolysis.

Results: At a minimum follow up of 3 years after operation (mean, 5.5 years), the mean Harris hip score was 89.4 points in the HA group and 89.0 points in the Non-HA group. The radiographic analysis did show the significantly earlier appearance of the endosteal spot welds in HA group. The spot welds at 1 and 2 year after operation were present in 48% and 70% of HA group, while 13% and 42% of Non-HA group. There was no significance at 3 years (71% vs 66%). More than 80% of the spot welds were seen at Gruen zone 6 in the both groups. No differences were noted regarding the radiolucent lines, calcar response, pedestal formation between the groups. There were no implant loosening and osteolysis in both groups.

Conclusions: These results suggest that the use of HA-coating does provide improved fixation in the early periods and the possibility of improved durability.

Introduction: When osteonecrosis is located in the medial portion of the femoral head, transtrochanteric curved varus osteotomy (varus), in which the lateral intact area is transposed to the weight-bearing portion, is indicated. The purpose of this study was to evaluate the clinical outcomes of this procedure.

Materials and Methods: Cases consisted of 60 hips in 52 patients with osteonecrosis of the femoral head who had a varus osteotomy from 1981 to 1998. Fifty-five hips out of 60 were followed (follow-up rate: 92%; 5 hips dropped out). The underlying associated factors were alcohol (5), trauma (2), and corticosteroids (40); 8 hips were from patients without a known factor (idiopathic). Nineteen were male and 36 were female. The average age was 34 years at the time of surgery. Forty-three hips were classified as ARCO Stage III-A, 11 in Stage III-B, and 1 in Stage IV.

Results: The average follow-up was 8.1 years (range, 0.8 to 20 years). The average preoperative Harris Hip Score of 51 points improved to an average of 81 at the latest follow-up. Radiographically, osteonecrosis in 46 hips (84%) healed or had no progression of collapse. Nine hips (16%) showed osteoarthritic changes, including progression of collapse, in which 4 cases had undergone conversion to THA. The post-operative intact area ratio in these 4 cases was 16%, while that in the other 51 cases was 70% (p< 0.005).

Discussion: When the intact area remains at the lateral portion of the femoral head, varus osteotomy is useful not only for healing of the necrotic lesion but also for the prevention of osteoarthritis. If the intact area ratio is over 34 % with hip abduction, varus osteotomy is indicated.

We have studied the effect of hydroxyapatite (HA) coating in 15 ovariectomised and 15 normal rats which had had a sham procedure. Twenty-four weeks after operation, HA-coated implants were inserted into the intramedullary canal of the right femur and uncoated implants into the left femur. The prostheses were removed four weeks after implantation. Twelve specimens in each group had mechanical push-out tests. Sagittal sections of the other three were evaluated by SEM.

The bone mineral density (BMD) of the dissected left tibia was measured by dual-energy x-ray absorptiometry. The difference in BMD between the control and ovariectomised tibiae was 35.01 mg/cm² (95% CI, 26.60 to 43.42). The push-out strength of the HA-coated implants was higher than that of the uncoated implants in both groups (p < 0.0001), but the HA-coated implants of the ovariectomised group had a reduction in push-out strength of 40.3% compared with the control group (p < 0.0001).

Our findings suggest that HA-coated implants may improve the fixation of a cementless total hip prosthesis but that the presence of osteoporosis may limit the magnitude of this benefit.

Particulate wear debris is associated with periprosthetic inflammation and loosening in total joint arthroplasty. We tested the effects of titanium alloy (Ti-alloy) and PMMA particles on monocyte/macrophage expression of the C-C chemokines, monocyte chemoattractant protein-1 (MCP-1), monocyte inflammatory protein-1 alpha (MIP-1α), and regulated upon activation normal T expressed and secreted protein (RANTES). Periprosthetic granulomatous tissue was analysed for expression of macrophage chemokines by immunohistochemistry. Chemokine expression in human monocytes/macrophages exposed to Ti-alloy and PMMA particles in vitro was determined by RT-PCR, ELISA and monocyte migration.

We observed MCP-1 and MIP-1α expression in all tissue samples from failed arthroplasties. Ti-alloy and PMMA particles increased expression of MCP-1 and MIP-1α in macrophages in vitro in a dose- and time-dependent manner whereas RANTES was not detected. mRNA signal levels for MCP-1 and MIP-1α were also observed in cells after exposure to particles. Monocyte migration was stimulated by culture medium collected from macrophages exposed to Ti-alloy and PMMA particles. Antibodies to MCP-1 and MIP-1α inhibited chemotactic activity of the culture medium samples.

Release of C-C chemokines by macrophages in response to wear particles may contribute to chronic inflammation at the bone-implant interface in total joint arthroplasty.

We exposed human macrophages isolated from the peripheral blood of healthy donors to metal and bone-cement particles from 0.2 to 10 μm in size.

Zymography showed that macrophages exposed to titanium alloy and polymethylmethacrylate (PMMA) particles released a 92- and 72-kDa gelatinase in a dose- and time-dependent manner. Western immunoblotting confirmed that the 92- and 72-kDa gelatinolytic activities corresponded to matrix metalloproteinase-9 and matrix metalloproteinase-2 (MMP-9, MMP-2), respectively. Western immunoblotting also indicated that titanium alloy and PMMA particles increased the release of MMP-1. Northern blotting showed elevated mRNA signal levels for MMP-1, MMP-2, and MMP-9 after exposure to both types of particle. Collagenolytic activity also increased in the macrophage culture medium in response to both types of particle.

Our findings support the hypothesis that macrophages release MMPs in proportion to the amount of particulate debris within periprosthetic tissues.