INTRODUCTION

Total Knee Arthroplasty (TKA) is a durable procedure which allows most patients to achieve a satisfactory functional level, but there can be instability under stressful conditions. Instability is one cause of early revision, often due to misalignment or inadequate ligament balancing. Persistent instability may cause elevated polyethylene wear. Lower levels of instability may cause patient discomfort with certain stressful activities. Hence quantifying instability may have an important role in the functional evaluation of TKA. Several previous studies showed that accelerometers have advantages in kinematic studies including low cost, ease of application, and application to any activity. The aim of this study was to demonstrate the use of an accelerometer attached to the anterior of the tibia, as an evaluation of knee stability of TKA patients. It was postulated that accelerations between TKAs and normal controls will be different, which could indicate abnormal TKA kinematics involving instability, especially for high intensity activities.

It has been suggested that the wear of ultra-high molecular weight polyethylene (UHMWPE) in total hip replacement is substantially reduced when the femoral head is ceramic rather than metal. However, studies of alumina and zirconia ceramic femoral heads on the penetration of an UHMWPE liner in vivo have given conflicting results.

The purpose of this study was to examine the surface characteristics of 30 alumina and 24 zirconia ceramic femoral heads and to identify any phase transformation in the zirconia heads. We also studied the penetration rate of alumina and zirconia heads into contemporary UHMWPE liners. The alumina heads had been implanted for a mean of 11.3 years (8.1 to 16.2) and zirconia heads for a mean of 9.8 years (7.5 to 15).

The mean surface roughness values of the explanted alumina heads (Ra 40.12 nm and Rpm 578.34 nm) were similar to those for the explanted zirconia heads (Ra 36.21 nm and Rpm 607.34 nm). The mean value of the monoclinic phase of two control zirconia heads was 1% (0.8% to 1.5%) and 1.2% (0.9% to 1.3%), respectively. The mean value of the monoclinic phase of 24 explanted zirconia heads was 7.3% (1% to 26%).

In the alumina group, the mean linear penetration rate of the UMWPE liner was 0.10 mm/yr (0.09 to 0.12) in hips with low Ra and Rpm values (13.22 nm and 85.91 nm, respectively). The mean linear penetration rate of the UHMWPE liner was 0.13 mm/yr (0.07 to 0.23) in hips with high Ra and Rpm values (198.72 nm and 1329 nm, respectively). This difference was significant (p = 0.041).

In the zirconia head group, the mean linear penetration rate of the UHMWPE liner was 0.09 mm/yr (0.07 to 0.14) in hips with low Ra and Rpm values (12.78 nm and 92.99 nm, respectively). The mean linear penetration rate of the UHMWPE liner was 0.12 mm/yr (0.08 to 0.22) in hips with high Ra and Rpm values (199.21 nm and 1381 nm, respectively). This difference was significant (p = 0.039).

The explanted zirconia heads which had a minimal phase transformation had similar surface roughness and a similar penetration rate of UHMWPE liner as the explanted alumina head.

Although total knee arthroplasty (TKA) has been a reliable procedure providing durable pain relief, polyethylene (PE) wear remains a major limitation of the long-term success of TKA. One potential method of lowering PE wear in TKA is to use oxidized zirconium (OxZr)-bearing surface. Although wear simulating testing of an OxZr counter surface of femoral component produced less PE wear and fewer particles than did cobalt-chrome (Co-Cr) counter surface of femoral component [1–4], this finding has not been demonstrated in vivo to our knowledge.

We measured in vivo PE wear by isolating and analyzing PE wear particles in synovial fluid from wellfunctioning TKA [5]. The purpose of the current study was to determine the size, shape, and amount of PE wear particles isolated from synovial fluid of patients who underwent a bilateral simultaneous TKA prosthesis, but different materials of femoral components.

We performed a bilateral simultaneous TKA in 100 patients (200 knees) who received an OxZr femoral component in one knee and a Co-Cr femoral component in the other. Mean age was 55.6 (44–60) years. Synovial fluid was obtained from 28 patients (56 knees) who had undergone a simultaneous bilateral TKA under completely sterile conditions at one or two years after the operation. Randomization to an OxZr or Co-Cr femoral component was accomplished with use of a sealed study number envelope, which was opened in the operating room before the skin incision had been made. After the opening the randomization envelope, the first knee received prosthesis indicated by the envelope (OxZr or Co-Cr component) and the contralateral (second TKA) knee received the other prosthesis (OxZr or Co-Cr component).

All operations were performed by one surgeon using the same design of total knee prosthesis: Genesis II (Smith and Nephew, Memphis, Tennessee). Only the material of the femoral component differed between two groups. The preoperative diagnosis was osteoarthritis in all patients. Preoperative and post operative KS and HSS knee scores, KS functional scores and UCLA activity scores were evaluated.

The amount of polyethylene wear particles in the aspirated synovial fluid sample was analyzed by thermogravimetic analysis (TGA) using a TGA instrument (TGA/SDTA 84le model, Mettler Toledo CO., Greifensee, Switzerland). The weight of the sample solution was measured before and after removing the organic content by heating the sample solution. The sample solution was casted onto petri dishes. The petri dish was covered and kept in a dry oven at 60°C for 2 days. While the sample solution was kept in a dry oven for 2 days, a small hole was made on the cover of the petri dish to allow water to evaporate slowly for 2 days. After this procedure, the cover of petri dish was removed and TGA sample was dried at 60°C for another 2 days. After the sample was completely dried out, the dried sample was measured using analytical balance.

TGA was used to determine the weight change profiles of polyethylene subject to heating under a nitrogen atmosphere. The nitrogen flow rate was kept constant at 50mL per minute. TGA data were taken at heating rate as 5°C per minute in the temperature range of 20° to 1000°C. The weight loss data were recorded as a function of time and temperature using special software in computer. When the temperature reached to the point of decomposition of the sample, the sample started to lose weight. By calculating the weight of the sample around the temperature which led to start to decomposition, real amount of polyethylene in the sample was measured. The size and shape of PE particles were examined using scanning electron microscopy (JSH-6360A model, Jeol Co., Tokyo, Japan). The samples were coated using a platinum sputtering machine for 20 sec.

ANOVA, nonparametric chi square test, nonpaired t-test and Mann-Whitney U-test were used for statistical analyses. Differences of P< 0.05 were considered statistically significant.

Mean preoperative KS (27.5 vs 27.2 points) scores, HSS (51.1 vs 51.2 points) knee scores, KS functional scores (55.4 vs 55.4 points) and UCLA activity scores (2.8 vs 2.8 point) were not significantly different between two groups. Mean postoperative KS (93 vs 92 points), HSS knee scores (90 vs 89 points), KS functional scores (78 vs 78 points), and UCLA activity scores (7.8 vs 7.8) were not significantly different. Mean weight of the polyethylene particles was 0.0219 g (SD, 0.0058) in the Co-Cr femoral component groups and it was 0.0214 g (SD, 0.005) in the OxZr group. This difference was not significant (P=0.711139, paired t-test). The size of particles was not different between the two groups. Also, shape of particles was not different between the two groups.

Under the condition and the duration of this study in this specific group of patients, TKA with OxZr or Co-CR femoral knee component had excellent clinical and radiographic outcomes with no osteolysis. While the wear simulator test in vitro demonstrated significant decrease in PE particles in the knees with an OxZr femoral component, our study in vivo revealed that total particle weight, size, and shape of PE wear particles were similar in the knees with an OxZr femoral component and in those with a Co-Cr femoral component.

We aimed to analyze the clinical results of the patients according to joint line change who underwent navigation assisted cruciate ligament retention type mobile bearing total knee arthroplasty.

From September 2004 to January 2006, cruciate ligament retention type mobile bearing total knee arthroplasties using navigation system(Orthopilot^®, Aesculap) were performed for 50 knees in 45 patients (2 men, 43 women). The mean follow up period was 46(39~55) months and the mean age was 65. There was one case with rheumatoid arthritis and all other were degenerative arthritic cases. All surgeries were performed using navigation system. Proximal tibia resection was performed at the sclerotic level of medial tibial plateau. The distance from the lowest point of lateral tibial plateau (registered point) to the proximal resection plane was measured. Clinical outcome were compared between joint line elevation with more than 3 mm(20cases) and less than 3mm (30cases).

The mean joint line elevation was 1.93 mm (range −1~5mm). There were no significant difference in the clinical results according to the joint line change (p> 0.05). It may be suggested that the change of joint line in the range of −1 to 5mm in cruciate ligament retention type mobile bearing total knee arthroplasty result in satisfactory clinical outcome.

As the proximal femoral bone is generally compromised in failed hip arthroplasty, achievement of solid fixation with a new component can be technically demanding. Recent studies have demonstrated good short-term clinical results after revision total hip arthroplasty using modular distal fixation stems, but, to our knowledge, none have included clinical follow-up of greater than 5 years. The purpose of this study was to report the clinical and radiographic outcomes assessed 5 to 10 years following revision total hip arthroplasty with a modular tapered distal fixation stem.

We retrospectively evaluated 50 revision total hip arthroplasties performed using a modular tapered distal fixation stem Between December 1998 and November 2003. There were 15 men (16 hips) and 34 women (34 hips) with a mean age of 59 years (range, 36 to 80 years). The index operation was the first femoral revision for 46 hips, the second for 3 hips, and the fifth for 1 hip. According to the Paprosky classification, 5 femoral defects were Type II, 31 were Type IIIA, and 14 were Type IIIB. An extended trochanteric osteotomy was carried out in 24 (48%) of the 50 hips. Patients were followed both clinically and radiographically for a mean of 7.2 years.

The mean Harris hip score improved from 54 points preoperatively to 94 points at the time of the latest follow-up. The mean stem subsidence was 1.5mm. Three stems subsided more than 5 mm, but all have stabilized in their new positions. During follow-up, a total of 4 hips required additional surgery. One hip had two-stage re-revision due to deep infection, one had liner and head exchange for alumina ceramic head fracture, and the other two underwent isolated cup re-revision because of aseptic cup loosening and recurrent dislocation, respectively. No repeat revision was performed due to aseptic loosening of the femoral component. Complications included 6% intraoperative fractures, 4% cortical perforations, and 4% dislocations. There were no stem fractures at the modular junction.

The medium-term clinical results and mechanical stability obtained with this modular tapered distal fixation stem were excellent in these challenging revision situations with femoral bone defects.

Background: Metal on metal articulation is known to reduce wear and subsequent development of osteolysis. However, long-term results of THA using metal on metal articulation is not well validated, especially in young patients.

Methods: Ninety-three THA were performed in 78 patients who were younger than 50 years of age at index surgery. The mean age of the patients was 37 years old. One patient (1 hip) had had a resection arthroplasty due to deep infection, 1 patient (1 hip) had performed stem revision because of periprosthetic fracture and 2 patients died before ten years follow-up and were excluded. Five patients (5 hips) were lost to follow-up before 10 years. Sixty-nine patients (84 hips) were available for complete clinical and radiographic analysis after minimum 10 years follow-up(range, 10 – 14 years).

Results: The mean preoperative Harris hip score of 49 points improved to 92 points at the time of last follow-up. Twenty hips(21.5%) showed variable degrees of osteolysis. Three patients underwent revision surgery because of focal pelvic osteolysis in one, aseptic loosening with extensive pelvic osteolysis of acetabular component in two. Three subsidence of femoral stem in other patients were identified.

Conclusions: At a minimum 10 years after THA using metal-on-metal articulation, it showed good results with regard to aseptic loosening in this group of young patients. However, relatively high rate of osteolysis in this articulation remains problematic and needs further investigation.

Background: Although many of the contemporary fixed- and mobile bearing total knee systems have been using extensively world wide, there is limited information available regarding the incidence of osteolysis of the well functioning total knee arthroplasties. We performed this study to evaluate the clinical and radiographic outcomes, the incidence of osteolysis, the revision rates and implant survivorship of the fixed- and mobile-bearing total knee arthroplasties at ten to seventeen years follow-up.

Methods: We compared 488 patients (894 knees) who received a fixed-bearing total knee replacement and 445 patients (816 knees) who received a mobile-bearing total knee replacement. There were 187 men and 301 women (mean age, 58.6 years) in the fixed-bearing group and 167 men and 278 women (mean age, 55.7 years) in the mobile-bearing group. The mean follow-up was 12.6 years (range, ten to seventeen years) in the fixed-bearing group and 14.1 years (range, twelve to seventeen years) in the mobile-bearing group.

Results: The mean postoperative Knee Society knee and functional scores were 92.9 points and 83.5 points, respectively in the fixed-bearing group. The mean postoperative Knee Society knee and functional scores were 90.7 points and 83.8 points, respectively. Incidence of osteolysis was 1.6% (fourteen of 894 knees) in the fixed-bearing group and it was 2.2% (eighteen of 816 knees) in the mobile-bearing group at the final review. Revision rate was 3.7% (thirty-three of 894 knees) in the fixed-bearing group and it was 2.7% (twenty-two of 816 knees) in the mobile-bearing group. Kaplan-Meier survivorship of the fixed-bearing group was 96.3% (95% confidence interval, 0.87–1.0) at 13 years follow-up and it was 97% (95% confidence interval, 0.90–1.0) of the mobile-bearing group at 14 years follow-up.

Conclusions: The present study demonstrates that the clinical and radiographic outcomes, the incidence of osteolysis, the rate of revision and the implant survivorship were similar between the fixed-bearing and mobile-bearing total knee arthroplasties.

Background: Alumina ceramic-on-highly cross-linked polyethylene (Al-on-X-linked PE) is attractive because of the potential for reduced wear, osteolysis and loosening of the component. The purpose of this study was to evaluate the clinical and radiographic outcomes of cement-less total hip arthroplasties (THAs) using Al-on-X-linked PE bearing and to determine the rates of osteolysis using radiographs and computer tomographic (CT) scans in young patients with osteonecrosis of femoral head.

Methods: Consecutive primary cementless THAs using Al-on-X-linked PE bearing were performed in 71 patients (73 hips) who were younger than 50 years of age with osteonecrosis of the femoral head. There were 48 men (51 hips) and 23 women (23 hips). The average age at the time of the index arthroplasty was 45.5 years (range, 20 to 50 years). Osteolysis was evaluated using radiographs and CT scanning. The average follow-up was 10.5 years (range, 10 to 13 years).

Results: The mean preoperative Harris hip score was 50.6 points (range, 27 to 55 points), which was improved to 96 points (range, 85 to 100 points) at the final follow-up. Preoperative functional activity was improved significantly (p=0.001) at the latest follow-up. All acetabular and femoral components were fixed by bone ingrown. The mean polyethylene linear penetration was 0.05±0.02 mm per year (range, 0.02 mm to 0.08 mm per year). Radiographic and CT scans demonstrated that no acetabular or femoral osteolysis was detected in any hip at the latest follow-up.

Conclusions: The current generation of anatomic tapered cementless femoral component with Al-on-X-linked PE bearing is functioning well with no osteolysis at a 10-year minimum and average of 10.5-year follow-up in this series of young patients with osteonecrosis of the femoral head.

Background: Whether total knee arthroplasty using computer-assisted surgical navigation can improve the limb and component alignment is a matter of debate. We hypothesized that total knee arthroplasty using computer-assisted surgical navigation is superior to the conventional total knee arthroplasty with regard to the precision of implant positioning.

Methods: Sequential simultaneous bilateral total knee arthroplasties were carried out in 160 patients (320 knees). One knee was replaced using a computer-assisted surgical navigation system and the other conventionally without using computer-assisted surgical navigation. The two methods were compared for accuracy of orientation and alignment of the components determined by radiographs and computed tomographs. The mean follow-up was 3.4 years.

Results: The mean preoperative Knee Society score was 26 points in the computer-assisted total knee arthroplasty group, which was improved to 92 points postoperatively and it was 25 points, which improved to 93 points post-opertively in the conventional total knee arthroplasty group. Ranges of motion of the knees were similar in both groups. The operating and tourniquet times were significantly longer in the computer-assisted total knee arthroplasty group than in the conventional total knee arthroplasty group (P< 0.001). Accuracy and the number of outliers of component position between the two groups were not significantly different (P> 0.05).

Conclusions: Our data demonstrated that total knee arthroplasty using computer-assisted surgical navigation did not result in more accurate implant positioning than that achieved in conventional total knee arthroplasty, determined by both radiographs and computed tomographs.

Background: The main goals of total knee arthroplasty are pain relief and improvement of function and range of motion. To ascertain whether posterior cruciate-retaining-flex total knee prosthesis would improve pain, function and range of motion, we asked whether knee and pain scores, ranges of motion, WOMAC score, patient satisfaction, and radiographic results would be better in the knees with a high-flexion posterior cruciate-retaining prosthesis than in the knees with a standard posterior cruciate-retaining prosthesis.

Methods: Fifty-four patients (mean age, 69.7 years) received a standard posterior cruciate-retaining knee prosthesis in one knee and a high-flexion posterior cruciate-retaining knee prosthesis in the contralateral knee. Five patients were men, and forty-nine were women. The minimum follow-up was three years (mean 3.1 years). At each follow-up, the WOMAC score and range of knee motion were evaluated and patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and The Hospital for Special Surgery.

Results: The mean postoperative Knee Society and Hospital for Special Surgery knee scores were 93.7 and 89 points, respectively in the knees with a standard posterior cruciate-retaining prosthesis and those were 93.9 and 90 points, respectively in the knees with a high-flexion posterior cruciate-retaining prosthesis. The mean postoperative WOMAC score was 22 points. Postoperatively, the mean non-weight and weight bearing ranges of motion were 131° (range, 90° to 150°) and 115° (range, 75 to 145°), respectively in the knees with a standard prosthesis and those were 133° (range, 90° to 150°) and 118° (range, 75 to 145°), respectively in the knees with a highflexion prosthesis. Patients satisfaction and radiographic results were similar in both groups. No knee had aseptic loosening, revision, or osteolysis.

Conclusions: After a minimum follow-up of three years, we found no significant differences between the two groups with regard to range of knee motion or clinical and radiographic results.

Hyaluronic acid (Hyalunan, HA), β-1,4-linked D-glucuronic acid and β-1,3 N-acetyl-D-glucosamine polysaccharide, is a nonsulfated glycosaminoglycan(GAG) conserved in the extracellular matrix (ECM). Due to its biocompatibility, biodegradable properties, HA is widely applied for tissue engineering. However, HA also has defects for tissue engineering such as mechanical properties, difficulty of handling. Thus, it is various modified by chemical reaction to produce HA derivative. HA plays an important role in tissue morphogenesis, proliferation and cell differentiation. Ascorbic acid (AA) has an effect on collagen synthesis and bone mineralization. Ascorbate levels also have a significant effect on osteoblast proliferation and alkaline phosphatase (ALP) expression. However AA is weak to heat and light, thus it is easily degradable. Consequently, we conjugated HA with AA in order to make it more stable and effective. In this study, we prepared HA-AA conjugate and evaluated activity of products in pre-osteoblast.

To produce more effective conjugation, we synthesised HA derivative, HA-N-hydroxysuccinimide, an activated ester of the glucuronic acid moiety. This HA-active ester intermediate is a precursor for drug-polymer conjugates. The degree of substitution was calculated by NMR analysis. The modified HA was dialysed and lyophilised. The yield of conjugation is calculated by Gel Permeation Chromatography (GPC). After the process, HA was conjugated with AA once again as previously mentioned. In this study, the resultant HA-AA conjugate was tested on MC3T3-E1, murine pre-osteoblast cells. We examined cellular viability (cytotoxicity), proliferation and gene expression. The expression of Type 1 collagen was examined by RT-PCR and western blot. Osteocalcin (OCN), osteopontin (OPN) and bone sialoprotein (BSP), bone proliferation and differentiation marker were detected by RT-PCR. Alkaline phosphatase assay was also performed. For confirmation on bone mineralization, alizarin red staining and von Kossa staining was performed.

In conclusion, the in vitro data demonstrate that HA-AA conjugate has an important role in bone formation, as it can increase proliferation and osteogenic differentiation of MC3T3-E1 cells. These observations further support the use of in vivo system for tissue engineering applications.

We have analyzed the long-term clinical and radiological results of 169 total knee replacements(TKRs) for rheumatoid arthritis over 10 years. The average follow up period was 12.8(10–17.6) years.

The flexion contracture was improved from average 25.0 to 2.9 degrees. But the angle of great flexion had decreased from average 128.0 to 114.7 degrees. At the final follow up, the American Knee Society knee score was 87.5 and function score 76.5 in average. The revision arthroplasty was performed in 20 cases, but only 4 cases were done before 10 years after the primary TKRs. The survival rate of the implant was 97.9% at 10 years and 85.3% at 14 years in Kaplan-Meier survivorship analysis. But just after 10 years, problems such as osteolysis and periprosthetic fractures started to occur increasingly. 10-year follow up results is just the 10-year results only, not the long-term or final results of TKRs for rheumatoid arthritis.

The purpose of this study was to evaluate the effect of decreasing tibial slope on extention gap during posterior stabilized total knee arthroplasty. 110 posterior stabilized total knee arthroplasties were studied for 2 groups;

having flexion contractures(n=35),

In each group, we measured the decrease of tibial slope and frequency of additional distal femoral resecions that were done due to insufficient extension gap in comparison with flexion gap during posterior stabilized total knee arthroplasty. We also compared frequencies of additional distal femoral resections between 2 parts having more and less slope decrease in each groups.

In each group, tibial slope decrease were 8.7 degrees, 7.4 degrees(p=0.145) and frequencies of additional resection were 51.4%, 24%(p=0.005) in average. In 2 parts having more and less slope decrease in each group, frequencies of additional resection were 44.4% vs 58.8%(p=0.505), 13.2% vs 35.1%(p=0.032). Results suggested that more decrease of tibial slope reduced frequency of additional distal femoral resection during posterior stabilized total knee arthroplasty in group having no flexion contracture.

Decreasing tibial slope can be considered as a factor influencing on extension gap during posterior stabilized total knee arthroplasty. The estimation of predictable tibia slope decrease through preoperative radiologic findings can be beneficial in performing succeful posterior stabilized total knee arthroplasty.

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.

To know how to succeed and survive for his or her whole life after the primary TKA by studying the causes of aseptic failure of the cruciate retaining type primary TKA. One hundred and seventy nine cases of revision of the TKA were analyzed concerning the causes of failure. The longest follow-up period was 25 years. All cases of the immediate postoperative and pre-revision weight bearing x-rays were reviewed. The operative findings of the revision surgery were compared with the pre-revision x-rays and physical findings.

The results of this study were:

The incidence of wear of the tibial polyethylene insert was predominant.

All aseptic failures occurred in high flexion knees. The causes of failures could be classified into four, the implant design, the bone cutting and the soft tissue balance and fixation. Long time survival could be achieved if those factors are perfect.

The purpose of this study is to analyze clinical and radiological results of total hip arthroplasty using the 3rd generation ceramic on ceramic articular surface.

Between July 1999 and May 2005, 339 hips of 250 patients had primary cementless total hip arthroplasty with the 3rd generation ceramic on ceramic bearing implants. And 325 hips of 236 patients were followed up over 3 years. Male were 168 patients(237 hips) and female were 68 patients(88 hips). The mean age at the time of operation was 47.3(range, 25~76) years old and the mean follow up period was 62.4(range, 36~107.6) months. The preoperative diagnoses were osteonecrosis of the femoral head (ONFH) in 250 hips, secondary osteoarthritis in 55 hips(dysplasia in 35, infection sequalae in 12, LCP in 2, CDH in 2), hemophilic arthropathy in 9 hips, ankylosing spondylitis in 7 hips etc.

We used Bicontact system(Aesculap, Germany) in 65 hips, Secur-FitTM(Stryker Howmedica Osteonics, USA) in 206 hips, Trilogy ABTM (Zimmer, USA) in 54 hips. Clinically, Harris Hip Score, thigh pain, squeaking and other complications were evaluated. Radiologically, the serial radiographs were analyzed.

Clinically, the Harris hip score was improved from preoperative 66.0(19~91) to 96.2(58~100) at the last follow-up. Radiologically, there was no loosening of implants and visible wear and osteolysis. Heterotopic ossifications were noted in 5 cases. In complications, there was dislocation in one case, periprosthetic fracture in 2 cases and thigh pain in 9 cases. Intermittent squeaking sound has occurred in 8 cases(2.5%). Among these, one case of loud squeaking which happened after fall down had revision surgery. There was no infection and fracture of ceramic implant.

Our midterm results of THA with the 3rd generation ceramic bearing system were very satisfactory and demonstrated that the 3rd generation ceramic bearings remain as an excellent bearing choice because of their superior wear characteristics. However, the results of this study suggests that the squeaking would be one of strong potential risk factors for failure of ceramic on ceramic total hip arthroplasty and we must be very cautious to prevent squeaking.

To investigate the amount and the factors of changes of the thickness of tibial polyethylene insert in revisional TKA compared to original thickness of primary TKA. We analyzed one hundred and twenty cases of wear, loosening and instability were included in this study. Infection cases were excluded. The period between the primary TKA and revision TKA was 88.5 months in average (range 1 to 17 year 3 months). The amount of increase of the tibial polyethylene thickness according to the main cause of failure and the wear site was analyzed.

The results of this study were: 1: The increased thickness was 6.7 mm in average. 2: The amount of increase in case of wear of anterior portion only was 2.3 mm, which was below the average. 3: The loosening cases showed 8.2 mm increase in average which was significantly greater than the average. 4: The cases of greater wear of medial side than lateral side showed 8.5 mm increase of the thickness which was significantly greater than the average. 5: The cases of only medial side wear showed 5.5 mm increase of the thickness, which was below the average. 6: The cases of the other causes such as patellar component wear, generalized wear, wear of posterior portion only, early wear less than 5 years after primary TKA because of flat polyethylene surface showed comparable amount of wear to the average.

The thickness of tibial polyethylene insert in revisional TKA compare to original thickness of primary TKA showed that it increased 6.7mm in average and was variable according to the cause of failure.

The purpose of this study was to examine surface characteristics of 30 alumina and 24 zirconia ceramic femoral heads and to identify phase transformation in zirconia heads. We also studied penetration rate of alumina and zirconia heads into UHMWPE liner. The alumina heads had been implanted for a mean of 11.3 years (8.1 to 16.2) and zirconia heads for a mean of 9.8 years (7.5 to 15).

The mean surface roughness values of explanted alumina heads (Ra 40.12 nm and Rpm 578.34 nm) were similar to those for the explanted zirconia heads (Ra 36.12 nm and Rpm 607.34 nm). The mean value of monoclinic phase of two control non-implanted zirconia heads was 1% (0.8–1.5) and 1.2% (0.9–1.3), respectively. The mean value of monoclinic phase of 24 explanted zirconia heads was 7.3% (1% to 26%).

In the alumina head group, mean linear penetration rate of UHMWPE liner was 0.10 mm/yr (0.09 to 0.12) in hips with low Ra and Rpm values (13.22 nm and 85.91 nm, respectively). The mean linear penetration rate of UHMWPE liner was 0.13 mm/yr (0.17 to 0.23) in the hips with high Ra and Rpm values (198.72 nm and 1329 nm, respectively). This differences was significant (P=0.041)

In the zirconia head group, the mean linear penetration rate of UHMWPE liner was 0.09 mm/yr (0.07 to 0.14) in hips with low Ra and Rpm values (12.78 nm and 92.99 nm, respectively). The mean linear penetration rate of UHMWPE liner was 0.12 mm/yr (0.08 to 0.22) in hips with high Ra and Rpm values (199.21 nm and 1381 nm, respectively). This difference was significant (P=0.039).

The explanted zirconia heads which had a minimal phase transformation had similar surface roughness and a similar penetration rate of UHMWPE liner as the explanted alumina head.

Architectural changes in occurring in the proximal femur (resorption) after total hip arthroplasty (due to stress shielding) continues to be a problem. In an attempt to reduce these bony changes the concept of short and femoral neck sparing stem designs have been advocated. The purpose of this study was to evaluate the early clinical and radiological results, especially stem fixation and bone remodeling of proximal femur after total hip arthroplasty.

A total of forty-five patients (fifty-four hips) were included in the study. There were twenty men and twenty-five women. The mean age at the time of operation was 53.9 years (range, twenty-six to seventy-five years). Clinical and radiological evaluation were performed at each follow-up. Bone densitometry was carried out on all patients one week after operation and at the final follow-up examination. The mean follow-up was 1.3 years (range, one to two years).

The mean preoperative Harris hip score was 45 points (range, 15 to 48 points), which improved to a mean of 96 points (range, 85 to 100 points) at the final follow-up. No patient complained of thigh pain at any stage. No acetabular or femoral osteolysis was observed and no hip required revision for aseptic loosening of either component. One hip (2%) required open reduction and fixation with a cable for calcar femorale fracture. Bone mineral densitometry revealed a minimal bone remodeling in the acetbulum and proximal femur.

The geometry of this ultra-short anatomic neck sparing cementless femoral stem has proved to provide effective initial stability even without the diaphyseal portion of the stem. We believe that femoral neck preservation and lateral flare of the stem provide an axial and torsional stability and more natural loading of the proximal femur.

Purpose: We have performed this study to compare the postoperative maximal flexion angle(MFA) of high-flex implants with that of conventional implants in PCL-substituted total knee arthroplasty(TKA).

Materials and Methods: The staged sequential bilateral TKAs were performed in Group 1, 35 patients(70 knees) with osteoarthritis of both knee. The conventional implant and the high-flex implant were both used in each patient by randomized method. The postoperative MFA of both type of implants was measured and analyzed at 1 year after surgery. To evaluate unidentified factors that might influence the results, such as the differences derived from personal characteristics during postoperative rehabilitation process achieving the range of motion of knee, we also analyzed the other patient groups, which were composed of Group 2(10 patients, 20 knees) bilaterally operated with conventional implants, Group 3(7 patients, 14 knees) bilaterally with high-flex implants, Group 4(13 patients, 13 knees) unilaterally with conventional implants and Group 5(17 patients, 17 knees) unilaterally with high-flex implant.

Results: In Group 1, the average postoperative MFA of high-flex implant and that of conventional implant showed no significant difference.(131.7 and 131.9 degree each) The average postoperative MFA in Group 1,2,3,4 and 5 showed no significant difference either.

Conclusion: This study indicates that the high-flex implant alone does not seem to improve the MFA as compared to the conventional implant. The status of the contralateral knee and the personal characteristics during rehabilitation seem to be more important factors in increasing the maximal flexion.