To compare 24-month patient-reported outcomes after surgical treatment or casting in patients age 60 years of age or older with unstable distal radius fractures (DRF's).

The Wrist and Radius Injury Surgical Trial (WRIST), is the largest randomized, multicenter trial in Hand Surgery, which enrolled 304 adults with isolated, unstable DRF's at 24 institutions. WRIST participants were followed for 24 months- longest follow-up among prospective studies comparing four treatment methods. Patients who agreed to surgical treatment (n=187) were randomized to internal fixation with volar plate (VLPS), external fixation, or percutaneous pinning; patients who preferred conservative management (n=117) received casting. The primary outcome was 24-month Michigan Hand Outcomes Questionnaire (MHQ) Summary score. Secondary outcomes were MHQ Domain scores.

At 24-month assessment, participants' mean MHQ Summary score was 86 (95% CI: 83,88), representing good hand function. Participants reported good return of their Activities of Daily Living (ADLs) with a mean MHQ ADL score of 88 (95% CI: 85,91). Finally, participants were satisfied, with a mean MHQ Satisfaction score of 84 (95% CI: 80,88). There were no significant differences in score by treatment group in any MHQ domain at 24 months. Six weeks after surgery, VLPS participants scored significantly higher than the other three groups on (ADLs) and Satisfaction (both p<0.0001), whereas participants who received external fixation scored significantly lower than the casting and VLPS groups on the same domains. By the 3-month assessment, the gap between VLPS and casting had disappeared but external fixation participants continued to report significantly worse scores. External fixation participants did not report comparable ADL scores to the other three groups until 12 months after surgery.

Participants reported good outcomes 24 months after DRF regardless of treatment. Casting and VLPS are both acceptable treatments for older adults. The decision between the two treatments should be made considering patient goals regarding recovery speed and desire to avoid surgical risks. External fixation should be avoided because of worse outcomes in the year after surgery and the risk of pin site infections.

Aims

Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation.

Aims

Commonly performed unicompartmental knee arthroplasty (UKA) is not designed for the lateral compartment. Additionally, the anatomical medial and lateral tibial plateaus have asymmetrical geometries, with a slightly dished medial plateau and a convex lateral plateau. Therefore, this study aims to investigate the native knee kinematics with respect to the tibial insert design corresponding to the lateral femoral component.

Objectives

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty with isolated medial or lateral compartment osteoarthritis. However, polyethylene wear can significantly reduce the lifespan of UKA. Different bearing designs and materials for UKA have been developed to change the rate of polyethylene wear. Therefore, the objective of this study is to investigate the effect of insert conformity and material on the predicted wear in mobile-bearing UKA using a previously developed computational wear method.

Isolated liner and head exchange procedure has been an established treatment method for polyethylene wear and osteolysis when the acetabular component remains well-fixed. In this study, its mid-term results were evaluated retrospectively in 34 hips.

Among the consecutive patients operated upon from September 1995, 2 patients (3 hips) were excluded because of inadequate follow-up and the results of remaining 34 hips of 34 patients were evaluated. They were 20 men and 14 women with a mean age of 49 years at the time of index surgery. Conventional polyethylene liner was used in 26 cases and highly cross-linked polyethylene liner was used in 8 cases. In 3 cases, liner was cemented in the metal shell because compatible liner could not be used. After a minimum follow-up of 5 years (range, 5∼20.2), re-revision surgery was necessary in 10 cases (29.4%); 8 for wear and osteolysis, 2 for acetabular loosening. In all re-revision cases, conventional polyethylene was used. There was no failure in the cases in which highly cross-linked polyethylene was used. There was no case complicated with dislocation.

The results of this study suggest more promising results with the use of highly cross-linked polyethylene in isolated liner exchange.

Background

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

Purpose

The purpose was to compare the accuracy of the method using 3D printing model with the method using picture archiving and communication system (PACS) images in high tibial osteotomy (HTO).

Objectives

Preservation of both anterior and posterior cruciate ligaments in total knee arthroplasty (TKA) can lead to near-normal post-operative joint mechanics and improved knee function. We hypothesised that a patient-specific bicruciate-retaining prosthesis preserves near-normal kinematics better than standard off-the-shelf posterior cruciate-retaining and bicruciate-retaining prostheses in TKA.

Background

Tissue engineering strategies to heal critical-size bone defects through direct bone formation are limited by incomplete integration of grafts with host bone and incomplete vascularisation. An alternative strategy is the use of cartilage grafts that undergo endochondral ossification. Endochondral cartilages stimulate angiogenesis and are remodeled into bone, but are naturally found in only small quantities. We sought to develop engineered endochondral cartilage grafts using human osteoarthritic (OA) articular chondrocytes.

Although total hip arthroplasty is highly successful for treatment of osteoarthrosis of hip joint, it is skill demanding surgery to perform and even more challenging in case of revision with bone defects. There are many options available for reconstruction of acetabular bony defects. Here, we evaluate the outcome of acetabular bony defect reconstructed with trabecular metal augments in short term.

We performed, 22 revision total hip arthroplasties and 6 primary total hip arthroplasties (total 28 in 28 patients) using trabecular metal augments to reconstruct acetabular defect between 2011 to 2015. Out of these 28 patients, 18 were males and 10 were females. Mean age of these patients was 61.2 years (range: 46 years to 79 years). Pre-operative templating was done for all cases and need for trabecular metal augments was anticipated in all cases. All cases were classified according to Paprosky classification for acetabular bone defects. Out of 28 patients, 3 had type 2B, 1 had type 2C, 18 had type 3A and 6 had type 3B acetabular defects. Post operatively, all patients were followed at regular interval for their clinical and radiological outcome. An average follow up was 20.1 months (range: 6 months to 42.5 months). We assessed clinical outcome in the form of Herris hip score (HHS) and radiological outcomes in form of osteolysis in acetabular zones and osseointegration, according to the criteria of Moore.

The average Harris hip score (HHS) was improved from 58.0 preoperatively to 87.2 postoperatively. The average degree of cup abduction at the final follow up was 44.29. The centre of rotation of the hip joint was corrected from average 38.90mm (range: 22.15mm to 66.35mm) above the inter-teardrop line preoperatively to average 23.85mm (range: 11.82mm to 37.69mm) above the inter-teardrop line postoperatively. Out of 28 patients, 18 patients had three or more signs of osseointegration, according to the criteria of Moore, at the time of final follow up. Rest of patients, had one or two signs of osseointegration (5 patients had one sign and 5 patients had two signs). We had no patient with migration or loosening of acetabular components. No patient has osteolysis of acetabulum in any zone.

Trabecular metal augments provide good initial stability to acetabular cup as well as helpful to bring down the centre of rotation of the hip joint within limit of 35mm above the inter-teardrop line. They also facilitate osseointegration. Our study showed that the results of the trabecular metal augments in reconstruction of acetabular bony defects were successful even in short term. However, long term study is required for better evaluation.

Clinical and radiological results of total hip arthroplasty (THA) using proximally coated single wedge (PSW) cementless stems are generally excellent. The geometry of cementless stems and the morphology of proximal femurs (Dorr types) provide optimal fit for primary stability and secondary biologic fixation. Because the geometry of PSW shape is designed to be engaged at the metaphysis, cementless PSW stem is not traditionally recommended to Dorr type C femurs with concerns of inadequate implant-host bone contact and the risk of femoral fracture. Nevertheless, previous studies on PSW cementless stems have not examined long-term survivorship according to Dorr types of femur. Paucity of a long-term comparative study makes it difficult to know whether the PSW stem plays a role in Dorr type C femurs or not. We postulated that the PSW stem could achieve stable fixation without increased risk of femoral fracture even in Dorr type C femurs, and demonstrate acceptable long-term results. The aim of this study was to investigate differences of clinical and radiological outcomes of THA using PSW stem according to proximal femoral geometry (Dorr types) in more than a 10-year follow-up.

Three hundred and seven primary THA in 247 patients, which was performed with use of a single-designed PSW stem from 1997 to 2003 and was followed up for over 10 years, were included in this retrospective study. According to Dorr's criteria, 89 femora were classified as Type A, 156 as Type B, and 62 as Type C. The patients' mean age at operation was 43.2 years (range, 18.4 – 69.6 years). They were followed-up for an average of 13.2 years (the range, 10.0 – 17.3 years). All of the hips were evaluated clinically and radiologically with special attention to the occurrence of implant loosening and periprosthetic femoral fracture.

The mean preoperative Harris hip score (50.4±20.6 points) improved significantly to 95.6±9.0 points at the final follow-ups. The improvements were observed regardless of Dorr types (p<0.001 in all 3 groups). The incidence of thigh pain (p=0.704) was not significantly different among groups. Implant survivorship was 100% in all 3 groups. None of the stems were loosened or revised. No significant differences were observed in osteolysis (p=0.492), pedestal formation (p=0.323), or cortical hypertrophy (p=0.169) among the groups [Fig. 1]. Radiolucent lines less than 2mm in thickness in Gruen zone 4 were observed more in Dorr type C femora than in Dorr type A or B (p=0.003) [Fig. 2]. Spot weld (p<0.001) and stress shielding (p=0.010) of proximal femur were more pronounced in Dorr C type femora than in type A or B [Fig. 3]. The prevalence of intraoperative (p=0.550) or postoperative (p=0.600) femoral fractures were not significantly different among the groups.

From over a 10-year follow-up, the PSW stem provided excellent stem survivorship regardless of Dorr type with satisfactory outcomes. The remodeling process around the stem was more pronounced in Dorr type C femur. The present study shows that the PSW stem is a recommendable option for Dorr type C femur.

For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Alternative bearing surfaces has been introduced to reduce wear debris-induced osteolysis after total hip arthroplasty (THA) and offered favorable results. Large population-based data for total joint surgery permit timely recognition of adverse results and prediction of events in the future. The purpose of this study was to present the epidemiology and national trends of bearing surface usage in primary total hip arthroplasty (THA) in Korea using nationwide database.

A total of 30,881 THAs were analyzed using the Korean Health Insurance Review and Assessment Service database for 2007 through 2011. Bearing surfaces were sub-grouped according to device code for national health insurance claims and consisted of ceramic-on-ceramic (CoC), metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), and metal-on-metal (MoM). The prevalence of each type of bearing surface was calculated and stratified by age, gender, hospital type, primary payer, and procedure volume of each hospital.

The number of primary THAs increased by 25.2% from 5,484 in 2007 to 6,866 in 2011. The average age of the entire study population was 58.1 years, and 53.5% were male [Table 1]. CoC was the most commonly used bearing surface (76.7%), followed by MoP (11.9%), CoP (7.3%), and MoM (4.1%). The distribution of bearing surfaces was identical to that in the general population regardless of age, gender, hospital type, and primary payer [Table 2]. The mean age of patients that received hard-on-hard bearing surfaces (CoC and MoM) was significantly younger than that of patients receiving hard-on-soft bearing surfaces (CoP and MoP) (56.9 years vs. 62.6 years). During the study period, 55.1% of THAs that used a hard-on-hard bearing surface were performed in males, while 53.0% of THAs that used a hard-on-soft bearing surface were performed in females. The order of prevalence of bearing surfaces was identical in low- and medium-volume hospitals (CoC was first, MoP was second, CoP was third, and MoM was fourth). The mean hospital charges did not differ according to the bearing surface used, with the exception of CoP, which was associated with a lower mean hospital charge. There were no changes in the distribution of bearing surfaces in each year between 2007 and 2011. Overall, the percentage of THAs that used CoC bearing surfaces increased substantially from 71.6% in 2007 to 81.4% in 2011, while the percentage that used CoP, MoP, and MoM decreased significantly [Fig. 1].

One of the reasons for the dominant usage of hard-on-hard bearing surfaces may be that the principal diagnosis of primary THAs and the patient age group distribution in Korea differ from those in other countries. The most common indication for primary THA is osteonecrosis of the femoral head in Korea. In contrast, the majority of primary THAs are performed for osteoarthritis in Western countries. The choice of bearing surface may be affected by many factors, including the nation's medical delivery system, payment type, disease pattern, and age distribution of patients that undergo THA. In future, the results of a large-scale nationwide study on primary THAs using CoC bearing surfaces in Korea will be reported.

For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Background

A cell-based tissue-engineered construct can be employed for treating meniscal lesions occurring in the non-vascularized inner two-thirds. The objective of this study was to test the hypothesis that both pre-differentiation of human bone marrow derived stromal cells (hBMSCs) into chondrogenic lineage before cell seeding and platelet-rich plasma (PRP) pretreatment on a PLGA mesh scaffold enhances the healing capacity of the meniscus with hBMSCs-seeded scaffolds in vivo.

Objectives

We evaluated the accuracy of augmented reality (AR)-based navigation assistance through simulation of bone tumours in a pig femur model.

Few epidemiological studies from Asian countries have addressed this issue and reported that FAI is less prevalent in Asian population. The purpose of this study was to determine the prevalence of radiographic hip abnormalities associated with FAI in asymptomatic Korean volunteers. The authors hypothesized that the prevalence of FAI in Korean population would not be less than that in western population.

Two hundred asymptomatic volunteers with no prior hip surgery or childhood hip problems underwent three-view plain radiography (pelvis anteroposterior (AP) view, Sugioka view, and 45° Dunn view) of both hips. Cam lesions were defined as the presence of the following signs on each views: pistol-grip deformity, osseous bump at the femoral head-neck junction, flattening of the femoral head-neck offset, or alpha angle >50°. Pincer lesions were determined by radiographic signs, including crossover sign, posterior wall deficient sign, or lateral center-edge (CE) angle >40°. Only positive cases agreed by both observers were defined as true FAI-related deformities.

There were 146 male and 254 female hips, with a mean age of 34.7 years. On pelvis AP view, the prevalence of pistol grip deformity, bump, flattening, and alpha angle >50° was 1.3% (male 3.4%, female 0%), 0.8% (male 2.1%, female 0%), 0.8% (male 2.1%, female 0%), and 1.0% (male 2.7%, female 0%), respectively. On Sugioka view, the prevalence of bump, flattening, and alpha angle >50° was 9.8% (male 14.4%, female 7.1%), 13.5% (male 20.5%, female 9.4%), and 14.0% (male 26.7%, female 6.7%), respectively. On 45° Dunn view, the prevalence of bump, flattening, and alpha angle >50° was 8.0% (male 14.4%, female 4.3%), 17.5% (male 27.4%, female 11.8%), and 27.5% (male 44.5%, female 17.7%), respectively. The prevalence of cam lesion which was identified on at least one radiograph was 42.5% (male 62.3%, female 31.1%). The prevalence of cam lesion which was identified on ≥2 radiographs was 19.3% (male 30.8%, female 12.6%). The prevalence of cam type FAI (at least one cam lesion) was 2.0% (male 5.5%, female 0%) on pelvis AP view, 25.8% (male 37.0%, female 19.3%) on Sugioka view, and 35.8% (male 55.5%, female 24.4%) on 45° Dunn view. On pelvis AP view, the prevalence of crossover sign, posterior wall sign, and CE angle >40° was 20.0% (male 23.3%, female 18.1%), 20.8% (male 22.6%, female 19.7%), and 2.0% (male 2.7%, female 1.6%), respectively. The prevalence of pincer type of FAI (at least one pincer lesion) was 23.0% (male 27.4%, female 20.5%).

In asymptomatic Korean volunteers, the prevalence of cam type FAI was low on AP pelvis radiographs, whereas the prevalence of cam type FAI on Sugioka and 45° Dunn view was found to be comparable to that previously reported in Western populations. The prevalence of pincer type FAI in asymptomatic Korean volunteers was also comparable that in Western populations and was similar in both gender. Considering the high prevalence of FAI morphologic features on plain radiographs in asymptomatic Korean populations, it is also important to determine whether FAI is a cause of hip pain when considering surgery in Asian patients.

Introduction

Legg-Calve-Perthes disease (LCPD), a juvenile osteonecrosis of the femoral head (ONFH), can remain sequelae around hip joint, and results in osteoarthritis necessitating total hip arthroplasty (THA) in middle-age. THA for sequelae of LCPD needs specific concerns for anatomical deformity, leg length discrepancy (LLD), and relatively young patient's age. To date, few studies are available for the results of THA for LCPD sequelae. Moreover, there was no study for the result of Alumina-Alumina THA (Al-Al THA) in patient with LCPD sequelae, even excellent long term outcome of Al-Al THA has been documented in relatively young patients. The aim of this retrospective study is to evaluate the clinical and radiological outcome of Al-Al THA for LCPD sequelae, especially in terms of the restoration of LLD and the occurrence of complication. In addition, we compared the results of THA for LCPD sequelae with those for adult onset ONFH, in which THA is necessitated in relatively young age and excellent long term outcome has been proven after Al-Al THA.

Background

Navigation systems that increase alignment accuracies of the lower limbs have been applied widely in total knee arthroplasty and are currently being adopted for minimally invasive UKA (MIS UKA) with good alignment results. There is little debate that when compared with total knee arthroplasty (TKA), UKA is less invasive, causes less morbidity, better reproduces kinematics, and therefore offers quicker recovery, better range of movement and more physiologic function.

However, despite improved alignment accuracies, advantages of use of navigation system in UKA in clinical outcomes and survivals are still debatable. To the best of our knowledge, no reports are available on the long-term results after UKA performing using a navigation system. The purpose of this prospective study was to compare the radiological, clinical, and survival outcomes of UKA that performed using the navigation system and using the conventional technique at average 8 years follows up.

Background

Despite the excellent clinical success of total knee arthroplasty (TAK), controversy remains concerning whether or not to resurface the patella. This has led to a number of randomized controlled trials. Randomized controlled trials constitute the most reliable source of evidence for the evaluation of the efficacy of a potential intervention. But most of these studies include all degree of osteoarthritis of the patellofemoral joint. So we did this prospective study to compare clinical and radiological outcomes after TKA with or without patellar resurfacing in patients with grade IV osteoarthritis on patellofemoral joint.

Background

The most important factors affecting the outcome of a TKA are restoring the normal mechanical axis and achieving optimum soft tissue balance. In the measured resection technique may have accompanying problems in imbalanced patients. Secondly individual variability of the reference points may affect the alignment of the bony cuts and thereby the alignment of the implant. The gap balance technique blends the soft tissue balance with the bony cuts and tries to overcome this problem. However proponents of the measured resection technique argue that no consideration is given to the coronal and rotational alignment of the femoral component in the gap balance technique. The ligament specific navigation assisted gap balance technique, tries to overcome these fallacies. The lateral ligaments and soft tissues act as a reference against which the medial soft tissues are balanced. Thus the reference becomes individualized and any variability is taken care of. Navigation assistance ensures control of the coronal and rotational alignment of the femoral component. The aim of the present study was two fold: - To describe our methodology of ligament specific navigation assisted gap balance technique and analyze the clinico-radiological outcome of our technique over an eight year follow up.

Summary Statement

Obovatol inhibits receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis and prevents inflammatory bone loss in mice

Purpose

The purpose of this study is to evaluate the midterm results of cementless revision total hip arthroplasty (THA) using Wagner Cone Prosthesis.

Purpose:

The purpose of this study was to evaluate the results of two stage reconstruction for infected arthroplasty of hip joint and to know the risk factor for failures.

The distal interphalangeal (DIP) joints of the fingers are prone to functional impotence in some degenerative diseases. In this case, different surgical techniques can be used, from DIP arthrodesis to joint denervation, much more confidential, which aims to preserve an already reduced mobility.

The four fingers (except the thumb) of 6 fresh hands from different cadavers were dissected under optic magnification. Two DIP joints were harvested from fresh dissected hands, in order to follow with the microscope the course of the nerve branchlets up to their articular entry. These two specimens were decalcified, and then embedded in paraffin. The blocks were serially cut in 5μm slices (1 slice each 250μm), which were observed at 25 and x100 magnification, after Masson’s trichrom staining.

A constant proximal articular branch, arising from the proper digital palmar nerve, was exclusively devoted to joint supply. This branch was located medially and arose in average at 7 mm from its entry point in the joint, where it was accompanied by small arterial branches. Before its entry into the inferomedial part of the DIP joint, it ran under the flexor digitorum profun-dus tendon. It then could divide into 2 or 3 branchlets. The proper digital palmar nerve abandoned, along its course, some nerve fibers to the tendinous synovium and neighboring structures. Then, ending its course, it gave off a distal articular branch, hidden among numerous cutaneous branches for the fingertip. The DIP joint nerve supply seems so under the exclusive dependence of the proper digital palmar nerve without any input from the dorsal side. On the histological slices, the nerves were mainly observed in peri- and intracapsular situation.

Could cutting these two articular nerves be sufficient to relieve pain from the DIP? This is what we are investigating through a clinical series; the first results are presented here.

Comminuted subtrochanteric fractures pose a clinical challenge; locking plate technology has been theorized to offer treatment advantages. A comminuted subtrochanteric femoral fracture model was created with a 2 cm gap below the lesser trochanter in fifteen matched pairs of human cadaveric femora confirmed to be non-osteoporotic. The femora were randomized to treatment with a trochanteric femoral nail (TFN), proximal femoral locking plate (PFLP), or 95° angled blade plate (ABP). Each was tested under incrementally increasing cyclic load up to 90,000 cycles to simulate progressive weight bearing during three months.

The TFN was the strongest implant: it withstood significantly more cycles, failed at a significantly higher force, and withstood a significantly greater load than either plate (p< 0.001). Varus collapse was significantly lower in the TFN construct (p< 0.0001). Mode of failure differed among implants, with damage to the femoral head through implant cut-out in five of ten blade plate specimens and two of ten nail specimens, whereas no damage to the femoral head bone was observed in any of the PFLP specimens.

The TFN was biomechanically stronger than the PFLP and this may have clinical relevance during the slow healing of subtrochanteric femoral fractures. The PFLP was biomechanically equivalent to the ABP but failure occurred without significant damage to the femoral head, suggesting that although biomechanically equivalent, the PFLP might have clinically relevant advantages in its mode of failure over the ABP.

Background: Traditionally, it is believed that structural failure of the ischemic epiphysis as well as changes in radiodensity seen in Legg-Calve-Perthes disease are due to repair. Little is known if bone material properties are altered following ischemic necrosis of the juvenile femoral head. Purpose of this study was to determine bone matrix mineralization density, an important determinant of bone quality and strength, in an experimental model of juvenile ischemic osteonecrosis.

Methods: Ten piglets were surgically induced with ischemic osteonecrosis and euthanized at 4- and 8 weeks following surgery. Contralateral, unoperated femoral heads were used as controls. Bone Mineralization Density Distribution (BMDD) parameters were determined using quanitative backscattered electron imaging (qBEI) in the epiphyseal calcified cartilage, subchondral and central trabecular bone region. Histological assessment was also performed.

Results: In necrotic calcified epiphyseal cartilage matrix as well as subchondral bone matrix, a significant increase in the degree (CaMean, Ca Peak) as well as the homogeneity of mineralization (CaWidth reduction) and a significantly reduced amount of low mineralized matrix (CaLow) were observed at 4 and 8 weeks post ischemia induction. In the necrotic central trabecular region a significant increase in the degree and homogeneity of mineralization, as well as a decrease in the amount of low mineralized bone was found at 8 weeks post-ischemia induction, but not at 4-weeks, indicating that changes in necrotic trabecular bone occur more slowly. Changes in the necrotic calcified cartilage region were more dramatic than in necrotic bone.

Discussion: Our findings indicate that the mineralization process continues in the necrotic calcified cartilage and bone following femoral head infarction. This leads to an increased degree and homogeneity of mineralization in calcified cartilage and bone matrices and therefore altered material properties. These alterations in matrix mineralization status would lead to more brittle bone, prone to micro-fractures and may partly explain the weakening of structural properties of necrotic bone. Moreover, an increase in calcified cartilage and bone mineralization may also explain the increased radiodensity seen in the early stage of Perthes disease prior to repair and/or structural failure.

The osseointegration of implants is related to the early interactions between osteoblastic cells and titanium surfaces. The behavior of osteoblast cells was compared on four different titanium surfaces in vitro and in vivo: machined, blasted, plasma spray and micro-arc oxidation.

X-ray diffraction and scanning electron microscope investigations were performed in order to assess the structure and morphology. Biologic and morphologic responses to the osteoblast cell lines (Saos-2) were then examined, using Promega proliferation assay, alkaline phosphatase activity, vβ3 integrin expression and cytoskeleton staining (Rhodamine-Phallodine). The analysis of gene expression for osteocalcin and collagen I was done through RT-PCR. In addition, differential histologic evaluation and interfacial strength at the bone-implant interfaces were then evaluated in the distal femur of four beagle dogs.

In conclusion, micro-arc oxidation of titanium appears to exhibit more favorable osteoblast adhesion and stronger interfacial strength than the compared groups in vitro and in vivo as well.

Uncontained peripheral bone defect in posteromedial tibial plateau is not an infrequent problem even in primary total knee arthroplasty, especially in Korean patients some of those have large angular deformities preoperatively.

We reviewed the clinical and radiological results of primary total knee replacements of 33 osteoarthritic knees in 28 patients with the use of metal block augmentation for uncontained peripheral tibial bone defects more than 5 millimeters in depth and more than a quarter of medial tibial plateau in width. Those defects were encountered in 75 knees (9.6%) during 779 primary total knee arthroplasties performed by single surgeon between January 2002 and December 2004 at our institution. Modular metal block augmentation was reserved for 42 knees, while the other knees were managed with bone-grafting or cement-filling techniques. Clinical and radiological follow-up more than 12 months were available from 33(78.6%) of 42 knees.

At a mean of 32.2 months (range:12~75 months), 31 knees (93.9%) except two cases of failure were evaluated as good or excellent. The average pre-operative American Knee Society Knee and Function scores were 32.5 and 38.6 respectively, which increased to 82.9 and 79.8 respectively at the latest follow-up. There were no radiolucent lines (RLLs) beneath the metallic block or tibial tray, which were progressive or more than 2 millimeters on radiographs, in those knees. Revisions were required for one delayed infection and another aseptic loosening of tibial component.

Non-progressive RLLs less than 2 millimeters at the cement-bone interface beneath the metallic block were noted in 10 (32.3%) of 31 knees. The RLLs appeared in 5 (41.7%) of 12 knees with metallic block augmentation alone and 5 (26.3%) of 19 knees which had been treated with the use of additional intramedullary stem augmentation, although this difference was not statistically significant. Since these radiolucent lines were not progressive or symptomatic at all, their clinical meanings or long-term consequences are not determined yet. All knees managed with the additional intramedullary stem augmentation revealed to have radiopaque lines adjacent to the stem on follow-up radiographs. The sclerotic halo around the tip of stem could be interpreted as evidence of the stem’s function in load sharing and might reflect secure fixation of tibial tray to bony interface.

We concluded that the use of modular metal block augmentation devices for peripheral tibial defects measuring more than 5 millimeters could provide a simple, rapid and dependable technique that provides predictable results. The observation that all knees managed with additional intramedullary stem augmentation would have sclerotic halo adjacent to the stem on follow-up radiographs may reflect an intramedullary stem is an important adjunct to bone defect management.

Biocompatibility of Co-Cr alloy was significantly improved by forming rough TiO2 layer on the surface. The TiO2 layer was formed by coating the Co-Cr alloy with Ti through electron beam deposition followed by micro-arc oxidation (MAO) of the Ti. Biocompatibility of Co-Cr alloy was enhanced by coating with titanium, and it was improved further by micro-arc oxidation treatment. MAO process was dependent on the thickness of coated titanium layer and applied voltage. There were close relationships between the phase, morphology and thickness of TiO2 layer and the applied voltage. Biocompatibility of the specimens coated with Ti and MAO treated after Ti coating were evaluated by in vitro ALP activity tests.

Personalized three-dimensional (3D) femoral geometry is a great aid in the surgical planning. X-ray image is still essential to diagnose and plan surgery in total hip replacement due to its lower cost and lower dose of radiation than computer tomography (CT). The purpose of the current study is to improve 3D reconstruction process using conventional X-ray images incorporating the anatomical parameters for building up the femoral model.

For 3D reconstruction, the personalized femoral appearance and parameters were firstly prepared from X-ray images and the referential CT model with anatomical parameters was modified as follows: the axial scaling, shearing transformation and radial scaling. In this study, the reconstruction algorithm was applied to X-ray images obtained from the 28 years old male.

The current study showed that this 3D reconstruction technique is clinically useful and feasible because this method was based on anatomical parameters and used for whole femur. This result can provide the basic model of individual femur for using finite element method of hip or knee joint, and designing the customized hip and knee implant. In addition, this result can be applied to the visualized 3D model with more effective parameters of individual femur in the surgery navigation system.

We evaluated 3 cases of ceramic-on-ceramic THA in that the evidence of the impingement between the metal neck and the ceramic liner was found.

Between July 2007 and January 2008, impingement between the metal and the ceramic liner was found in 3 cases of ceramic-on-ceramic THA during re-operation. The re-operation was performed 3–6 years after the primary surgery because of ceramic head fracture, deep infection and cup loosening. All patients frequently sat on the floor in tailor fashion but did not have any sound in the hip after THA.

In all cases, V-shaped indented wear scar was found on the postero-superior aspect of the metal neck. Two ceramic liners could be retrieved. Both showed black staining in the postero-superior portion of the rim. The outer edge of the bearing surface of the retrieved acetabular liners was evaluated with SEM. The black stained area of the acetabular liner rim was found to be roughened. A micro-crack propagating into the deep portion of the ceramic liner was observed in one liner.

Our observations suggest that impingement between the ceramic liner and the metal neck can cause crack formation leading to ceramic liner failure in vivo.

Many reports show good results following procedures, such as intervertebral body fusion using cage or total disc replacement, that restore adequate disc height. However, there have been no references regarding the range of normal lumbar disc height in Korean adults which can be used as a standard for the implant size. The purpose of our study is to measure the lumbar disc height on radiographs in normal Korean. 132 subjects (age range 20 to 40 years) who had no previous history of low back pain and no significant finding on physical examination were enrolled. Plain lateral lumbar spine radiograph in supine position were taken. Intervertebral disc heights were measured at anterior, middle and posterior portion of each lumbar disc. The average magnification rate was 115%, and the disc heights were corrected by the magnification rate in each segment.

Lumbar disc height showed cranio-caudal pattern in both male and female groups. L4–5 disc heights were highest at anterior, middle and posterior portion in male. L4–5 disc heights were highest at middle and posterior portion in female. L5-S1 disc height was highest at anterior portion in female, but there was no statistically significant difference between L4–5 and L5-S1 disc height at anterior portion. There was no significant difference in disc height between male and female except anterior portion of L1–2 and L2–3 disc. Statistically significant decrease in disc height was not presented in overweight person at all measured site in male and female except posterior portion of L1–2 disc in male.

This research is meaningful in that it is an attempt to provide a reference value of lumbar disc height in Korean adults, and the measured values may also be useful in manufacturing Korean modeled artificial lumbar disc prosthesis or surgical instruments for lumbar interbody fusion.

Introduction: Alendronate is a well known inhibitor of osteoclastic activity and is used for the treatment of various metabolic bone diseases. Recent studies indicate that alendronate may have additional effect on osteoblastic activity. In this study, we evaluated the effect of alendronate on the osteogenic differentiation of mouse mesenchymal stem cells.

Materials and Methods: D1 cells, known as multipotent mouse mesenchymal stem cells, were cultured in the presence of osteogenic differentiation medium (ODM) for 7 days, then treated with alendronates, and 2 days later the cells were used for testing. The cell proliferation was analyzed using an MTT assay. Alizarin red staining was done for mineralization. Alkaline phosphatase activity was measured using a commercial ELISA kit. Calcification was analyzed using energy dispersive X-ray spectrophometric analysis (EDX). Osteogenic gene expression was analyzed using RT-PCR. The change of CD 44 expression was observed using confocal microscopy and FACS analysis.

Results: The D1 cells, in the presence of ODM, differentiated into osteoblasts. The evidence of osteogenic differentiation was confirmed by the positive stain by Alizarin red S, the increased activity of ALP, the increased mRNA expression of osteocalcin, a calcium peak in the EDX analysis, and by the positive immunofluorescence staining against CD 44 (an antigen detected on osteoblasts). With the addition of alendronate in the ODM medium, the osteogenic differentiation was enhanced. The enhancing effect was confirmed by the increased intensity of the Alizarin red S staining, higher activity of ALP, the higher mRNA expression of osteocalcin, a higher calcium peak in the EDX analysis, and by the increased immunofluorescence staining against CD 44 in the FACS analysis.

Conclusion: We have demonstrated that alendronate enhances osteogenic differentiation when given to mouse mesenchymal stem cells in association with the ODM. Alendronate may increase the bone density not only by inhibiting the osteoclastic activity but also by increasing the osteogenic differentiation of the mesenchymal stem cells.

Introduction: The etiology of transient osteoporosis of the hip (TOH) remains unknown. Recently subchondral bone injury of the femoral head has been proposed as a possible etiology.

Methods: A 28-year-old woman presented with bilateral hip pain that started sequentially during the peripartum period. Diagnosis of TOH was made based on typical findings of plain radiographs and magnetic resonance images. The subchondral trabeculae of the femoral head were evaluated on serially taken coronal multiplanar reformation CT images.

Results: At 4 weeks after pain onset, a marked decrease in the sclerotic density with irregular discontinuation was observed in the primary compression trabeculae. At 12 weeks, a focal area of irregular thickening of trabeculae was observed. At 20 weeks, sclerotic density of trabeculae recovered markedly and the focal area of irregular trabecular thickening disappeared. At 1 year, subchondral trabeculae recovered almost completely.

Conclusion: Evidence of subchondral trabecular injury was observed in the femoral heads of TOH.

Introduction: Osteonecrosis of the femoral head occurs in young patients. The preservation of the hip joint is vitally important because hip replacement arthroplasty is associated with high rates of failure in young and active patients. Curved intertrochanteric varus osteotomy is one of several joint preserving procedures used to treat these patients.

Methods: Between June 2003 and June 2006, 46 patients (49 hips) who had osteonecrosis of the femoral head were treated with curved intertrochanteric varus osteotomy. There were 23 men and 23 women who had a mean age at the time of osteotomy was 33 years (range, 17 to 51 years). The osteotomy was fixed with a 120 degree compression hip screw in the first 34 hips and with a 95 degree dynamic condylar screw in the remaining 15 hips. Clinical evaluation was performed using the scoring system of Merle d’Aubigne et al. Radiological failure of the operation was defined as further collapse of the femoral head by more than 2 mm or progressive narrowing of the joint space compared with the immediate postoperative radiograph.

Results: The mean duration of follow-up was 22 months (range, 12 to 48 months). One patient (one hip) required a total hip arthroplasty due to loss of fixation and penetration of the lag screw into the joint space. In two patients (two hips), the plate fractured at 3 and 4 months after the operation, which was changed to a new plate. Thus, 48 of the 49 hips survived at a mean follow-up 22 months. In these 48 hips, the mean Merle d’Aubigne hip score was 17.2 points at latest evaluation and there was no instance of radiologic failure.

Discussion: Curved intertrochanteric varus osteotomy is a satisfactory joint preserving method to treat osteonecrosis of the femoral head.

Introduction: We evaluated the follow-up results of subchondral fatigue fractures of the femoral head.

Methods: Between July 1999 and August 2005, 10 male patients presented with a collapsed subchondral fatigue fracture of the femoral head. The flattening of the femoral head was mild in 4 cases, moderate in 3 cases and severe in 3 cases. Three cases were misdiagnosed as osteonecrosis and since treated with multiple drillings or bone grafts. One case was treated with impaction bone grafting. The remaining cases were treated non-operatively. All patients were followed more than 2 years after onset of hip pain.

Results: At the latest follow-up, no patient had remarkable pain or disability limiting daily activity. Degenerative changes of Tönnis grade 1 were observed in 5 cases.

Discussion: Unlike collapsed osteonecrosis, collapsed subchondral fracture of the femoral head had a benign clinical course.

Introduction: A hypothesis that combined necrotic angle measurement using MRI scans predicts the subsequent risk of collapse of femoral head osteonecrosis was tested.

Materials and Methods: Thirty-seven hips with early-stage osteonecrosis in 33 consecutive patients were investigated. The arc of the necrosis was measured by the method of Kerboul et al. using mid-coronal and mid-sagittal MRI scans of the femoral head instead of anteroposterior and lateral radiographs, and the two angles were added. Hips were classified into four categories based on the magnitude of the added angle; grade 1 (< 200), grade 2 (200–249), grade 3 (250–299), and grade 4 (≥300). After the initial evaluations, the hips were randomly assigned to a core-decompression group or a non-operatively-treated group. Patients underwent regular follow-up until femoral head collapse or for a minimum of five years.

Results: Seven hips in grade 4 and 16 hips in grade 3 developed femoral head collapse in 36 months; six out of nine hips in grade 2, and none of five hips in grade 1 developed collapse (log rank test, p< 0.01). In a retrospective analysis, none of four hips with combined necrotic angle < 190 (low risk group) collapsed, and all 25 hips with combined necrotic angle > 240 (high risk group) collapsed, and four (50%) of eight hips with combined necrotic angle between 190 and 240 (moderate risk group) collapsed during the study.

Discussion: The Kerboul combined necrotic angle ascertained by MRI scans instead of radiographs is a major predictor of future femoral head collapse.

Introduction: The purpose of this study was to evaluate the effectiveness of free vascularized fibular grafting (VFG) for the treatment of osteonecrosis of the femoral head.

Materials and Methods: We reviewed the results in a consecutive series of 115 hips (88 patients) who had undergone free VFG between July 1991 and February 1999. Among them, 46 hips (32 patients, 28 males and 4 females) were available with periodic follow-up of at least 5 years. The mean follow up period was 7.1 years (range, 5 to 13 years). An average age of patients was 37.6 years at the time of VFG. We performed survival analysis by the Kaplan-Meier method according to the stage, etiology, age of patients, size of involvement, and degree of collapse of the femoral head. We used the Harris hip score for clinical evaluation, and used plain radiographs and MRIs for radiological evaluation.

Results: The survival rates were 85% in Ficat stage 2a, 34.7% in stage 2b, and 76.2% in stage 3. Eleven hips were evaluated as failures of VFG of which 7 hips were converted to a prosthetic joint. Harris Hip Scores were 67.8 points preoperatively, and increased to 80.4 points postoperatively. Good or excellent results were found in 69.5% of hips clinically and 56.5% of the hips radiologically. Age and size of necrosis affected the postoperative Harris Hip Score significantly, but other factors did not.

Discussion: Free VFG for the early osteonecrosis of femoral head revealed satisfactory results with good survival of the joint and improvements in Harris Hip Scores.

In cementless fixation system, surface character becomes important factor. Alkali and heat treatments on titanium metal has been proved to show strong bonding to bone and higher ongrowth rate. In this study we examined the effect of alkali and heat treatments on titanium rod in rabbit femur intramedurally model, in consideration of cementless hip stem. The implant had a 5mm in diameter and 25 mm in length. The implants were and half of them were immersed in 5 mol/L sodium hydroxide solution and heated at 600 åé for one hour (AH implant), and the other half were untreated (CL implant). The implants were implanted into the distal femur of the rabbits, AH implant into left femur and CL implants into right. The bone-implant interfaces were evaluated at 3, 6, and 12 weeks after implantations.

Pull-out tests showed that AH implants significantly higher bonding strength to bone than CL implants at each week after operations. At 12 weeks mean pull-out load of AH implants was 411.7 N and that of CL implants 72.2 N. As postoperative time elapsed, histological examination revealed that new bone form on the surface of the both types of the implants, but significantly more bone contacted directly on the surface of AH implants. At 12 weeks AH implant was covered by the newly formed bone about 56% of the whole surface of the implants and CL implants was about 19%.

In conclusion, alkali- and heat-treated titanium offers strong bone-bonding and high affinity to bone instead of conventional mechanical interlocking mechanism. Alkali and heat treatments on titanium may be applicable to the surface treatment for cementless joint replacement implant.

Introduction: It is very important to evaluate the healing process in the femoral head after free vascularized fibular graft (VFG) in osteonecrosis of the femoral head (ONFH). Bone scintigraphy combined with a pinhole collimator, which is simple and not expensive, is used for very high resolution images of small organs, such as thyroid and certain skeletal regions. The purpose of this study was to assess the changes using pinhole bone scintigraphy in ONFH after VFG.

Materials and Methods: Changes of Tc-99m-HDP pinhole bone scintigraphy were analyzed in 22 cases of ONFH which were treated with VFG and had satisfactory results in patient evaluations at least 2 years after surgery. Harris Hip Scores were 90 points or more; and femoral head collapse was less than 2 mm.

Results: The results were: (1) At 1 week, the pinhole image showed no significant change in cold area but two linear RI uptakes corresponding to the fibular graft were noted. (2) At 3 months, localized hot uptakes just above the tip of the graft were observed in 17 cases (77.2%), and diffuse increased uptake surrounding the cold area were observed. (3) At 6 months, localized hot uptake were increased in size and replaced cold areas and delineated the shape of the superolateral aspect of the femoral head. (4) At 1 year, increased RI uptake of the superolateral aspect of the femoral head expanded medially in all cases. (5) After 2 years, cold areas faded away in 18 cases (81.8%).

Discussion: In conclusion, the authors believe that the Tc-99m-HDP pinhole bone scintigraphy is an excellent method to delineate the healing process in ONFH after VFG.

Introduction: The hypothesis that combined necrotic angle measurements using magnetic resonance imaging (MRI) scans predicts the subsequent risk of collapse of femoral head osteonecrosis was tested.

Materials and Methods: Thirty-seven hips with early-stage osteonecrosis in 33 consecutive patients were investigated. The arc of the necrosis was measured by the method of Kerboul et al using mid-coronal and mid-sagittal MRI scans of the femoral head instead of anteroposterior and lateral radiographs, and the two angles were added. Hips were classified into four categories based on the magnitude of the added angle; grade 1 (< 200°), grade 2 (200°–249°), grade 3 (250°–299°), and grade 4 (≥300°). After the initial evaluations, the hips were randomly assigned to a core-decompression group or conservatively-treated group. Patients underwent regular follow-up until femoral head collapse or for a minimum of five years.

Results: Seven hips in the grade 4 category and 16 hips in the grade 3 category developed femoral head collapse in 36 months; six out of nine hips in the grade 2 category, and none of five hips in the grade 1 category developed collapse (log rank test, p< 0.01). In a retrospective analysis, none of the four hips with a combined necrotic angle < 190° (low risk group) collapsed, whereas all 25 hips with a combined necrotic angle > 240° (high risk group) collapsed, and four (50%) of eight hips with a combined necrotic angle between 190° and 240° (moderate risk group) collapsed during the study.

Discussion: The Kerboul combined necrotic angle ascertained by MRI scans instead of radiographs is a major predictor of future collapse.

Introduction: Avascular necrosis (AVN) of bone is a process that is characterized pathologically by bone marrow ischemia and eventual death of trabecular bone. Following the development of the disease with the remodeling process, the microstructure and corresponding mechanical properties of the trabecular bone changes in different regions with different intensities. Eventually, the lesion leads to collapse of the femoral head and destruction of the hip joint. The most striking finding is the direct relationship between mechanical stress and the progressive collapse of the necrotic region. This study investigated the differences in the mechanical properties from the trabecular bone of the different regions in AVN of the femoral head using microfinite element models.

Materials and Methods: A 20mm cylindrical core sample was obtained from the necrotic zone of the human femoral head with pre-collapse disease throughout the overall head under the fluoroscope and then was scanned using Micro-CT. Region of interest (ROI) was determined in the necrotic, the reactive, and the sub-reactive zone respectively, which were created with the hexahedron mesh model; finite element analysis was performed.

Results: The histomorphology and FE-analysis of three zones revealed that the parameters of Tb. Th, BV/TV, reaction force, ultimated stress, and elastic modulus increase obviously in the reactive zone.

Discussion: The authors conclude that obvious increases of the parameters and the stress concentration in the reactive zone are due to the adaptive remodeling of trabeculae in the boundary zone between the necrotic and the normal zone.

Introduction: Necrotic fatty marrow is yellow, thick, and turbid like pus and the fat cell is counted as white blood cell in automated cell counting. When necrotic fatty marrow leaks into the hip joint through a crack in the cartilage of the osteonecrotic femoral head, a misdiagnosis of pyogenic infection can be made. The authors report cases of osteonecrosis of the femoral head, in which a misdiagnosis of pyogenic infection was made during the operation.

Materials and Methods: Between September 1997 and December 2001, pyogenic arthritis was suspected during the operation in seven patients who were operated on due to advanced osteonecrosis of the femoral head. The markers of infection including white blood cell count, erythrocyte sedimentation rate, and C reactive protein in preoperative laboratory examination were normal in all of the seven patients. Total hip arthroplasty was scheduled for all patients. When the hip joint capsule was incised, joint fluid gushed out in all patients. The appearance, white blood cell count in automated cell counting, microscopic findings, and the results of culture of the joint fluid were evaluated.

Results: The joint fluid was yellow, thick and turbid like pus. A pyogenic arthritis was suspected and the joint fluid was sent to the laboratory for automated blood cell count, smear and culture. The count of white blood cells ranged from 5800 to 18000 in automated cell counting. No microorganism was identified on joint fluid smear. On microscopic cell counting using a hemocytometer, white blood cells were rarely seen and the majority of cells which were counted as white blood cells, were necrotic fat cell. Total hip arthroplasty was performed immediately after microscopic examination of the joint fluid. No microorganism was identified in cultures of the joint fluid. There was no evidence of infection after total hip arthroplasty at a minimum of two-year followup.

Discussion: When necrotic fatty marrow leaks into the hip joint, the joint fluid looks like pus and white blood cell counts of the joint fluid is increased in automated cell counting because fat cells are counted as white blood cells. In this situation, microscopic examination of the joint fluid is necessary. If the white blood cell count is not increased in microscopic cell counting, replacement arthroplasty can be performed without risk of infection.

Introduction: Some patients with collapsed osteonecrosis of the femoral head do not need any specific treatment because of mild symptoms or disability. The general features of this patient population were evaluated.

Materials and Methods: Forty-five cases of collapsed osteonecrosis of the femoral head in 38 patients were included in this study. These patients visited outpatient clinics for the first time from January 1996 to December 2002. In all cases, pain developed at least 3 years before the last follow-up, but no specific treatment was necessary. There were 27 men and 11 women. The mean age at the onset of pain was 41 years (range, 17 to 72 years). The duration from the onset of pain to the last follow-up was 36 to 167 months (mean, 73 months). The general and radiological features were evaluated.

Results: Risk factors included steroid therapy in 18, alcoholism in 16, other in 1 case; 10 cases had no risk factors (idiopathic). In 29 patients, both femoral heads were involved. Extent of the necrosis was 37 to 89 percent (mean, 62 percent). The amount of depression was 0.5 to 17 mm (mean, 2.2 mm).

Discussion: Steroid therapy was the most frequent risk factor in this patient population. In most cases, the amount of depression was less than 3 mm. Most patients remembered that the pain was most severe at its onset and improved over the next several months.

Introduction: Stress fracture of the femoral head is a rare condition and usually occurs in people with poor bone quality as an insufficiency fracture. We evaluated the clinical aspects of subchondral fatigue fractures of the femoral head (SFFFH) that occurred in young healthy people.

Materials and Methods: Between January 1998 and November 2001, 7 cases of SFFFH in 5 patients were treated. The characteristics of this condition were ascertained by assessing the clinical course and findings of radiographs, bone scintigrams, and magnetic resonance (MR) images.

Results: All patients were male military recruits in their early twenties. Pain developed within 6 months after recruitment. On initial radiographs, definite abnormal findings were observed in 3 hips of 2 patients. In 2 of them, the femoral head was markedly collapsed. In the other 4 hips, no definite abnormal findings were noticed. The bone scintigrams showed increased radionuclide uptake in the femoral head. MR images demonstrated localized abnormal signal intensity areas (bone marrow edema pattern) in the femoral head. In all cases, MR crescent signs were observed. In the cases without collapse of the femoral head, the pain decreased gradually and disappeared completely in 6 months with improving findings on follow-up MR images. The collapsed cases needed surgical treatment: total hip arthroplasty or strut iliac bone grafting.

Discussion: When a military recruit or an athlete is complaining of hip pain, a high index of suspicion for SFFFH is necessary to prevent the collapse of the femoral head. Bone scintigrams are of great value as a screening tool. Osteonecrosis of the femoral head can be differentiated by the findings on MR images.

Introduction: Osteonecrosis of the femoral head (ONFH), a disease of unknown pathogenesis usually involves subchondral bone and shows an improper repair process. The temperature of the subchondral bone of the femoral head was found to increase by a maximum of 2.5 °C in a simulation of walking performed in cadavers. A greater increase in the temperature is expected in the necrotic bone in ONFH because there is no heat dissipation by blood flow. The purpose of this study was to confirm the possibility that hyperthermia is a cause of the poor regeneration of the necrotic bone in ONFH.

Materials and Methods: Necrotic and living bone extracts were prepared from the femoral heads of 4 ONFH patients. Human umbilical vein endothelial cells (HUVECs) were cultured with endothelial cell growth media-2 (EGM-2), EGM-2 supplemented with necrotic bone extracts, and EGM-2 supplemented with living bone extracts. HUVECs were also cultured at temperatures of 40, 40.5, 41 and 42 °C, while controls were maintained at 37 °C. Viable cell numbers of HUVECs were determined by MTS assay at days 1, 4, 6, 8, and 11.

Results: The number of viable cells decreased in hyperthermic conditions of 40.5 to 42 °C (p< 0.05). The addition of living bone extracts induced a significant increase in the number of viable cells during the culture periods (p< 0.05). Necrotic bone extracts did not induce such a significant increase.

Discussion: Local subchondral hyperthermia might be a possible cause of the poor regeneration of the necrotic area in ONFH.

Introduction: We have calculated the amount of antero-posterior diameter expansion by tibial intramedullary nails with distal anterior bend which were designed to prevent proximal posterior cortical fracture by the distal tip of a nail on insertion in the surgical treatment of tibial fracture.

Materials and Methods: Russell-Taylor® and AIM™ tibial nails were compared in respect to the amount of anteroposterior diameter expansion by the distal anterior bend of these nails. AIM™ tibial nails have shorter length but larger angle of distal anterior bend than Russell-Taylor® tibial nails. As Fig.1. shows, if we suppose that the length and angle of distal anterior bend of nail be L and _, respectively and the length of distal tapered portion be T, the amount of anteroposterior diameter expansion (E) by the distal anterior bend portion of the nail is [(L-T) _ sin_]. So, intramedullary nail with distal anterior bend passes down the medullary canal with an actual diameter (AD) of the sum of given diameter of the nail (D) and [(L-T) _ sin_] on anteroposterior plane.

Results: The amount of anteroposterior diameter expansion of Russell-Taylor® and AIM™ tibial nail was 2.81 mm and 3.26 mm more than the given nail diameter because the length and angle of distal anterior bend of Russell-Taylor® and AIM™ tibial nails were 64 mm, 3° and 47.5 mm, 5°, respectively and about 10 mm of distal tip of both nails are tapered to facilitate passage in the medullary canal.

Conclusion: On insertion of tibial nails with distal anterior bend, the anteroposterior diameter expansion effect by these nails should be carefully considered to prevent fracture of the isthmus. We think that the nail about 2 to 3 mm smaller than the final reamer used in diameter had better be used when you try to insert an intramedullary nail bent anteriorly at distal portion such as Russell-Taylor® and AIM™ tibial nails.