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Biomedical subjects

K Y Chiu

Publications and source records attributed to K Y Chiu.

At least 19 recordsLinked to original sources
PubMed2006

Cementless acetabular component inserted without screws - the effect of immediate weight-bearing.

Seventy-four total hip arthroplasties using a cementless acetabular component without holes for supplemental screw fixation were evaluated during a follow-up period of 2-6 years. Immediate full weight-bearing walking was allowed after the operation. A comparison of anteroposterior (AP) radiographs of the pelvis taken in the early postoperative period and when the patient returned for the final follow-up revealed that there was no migration of the acetabular component. Based on the early postoperative radiographs and using the zones described by Martell et al. [J Bone Joint Surg (1993) 75-A:554-571], gaps between the acetabular component and the bone occurred at zone A2 in three hips (4.1%), at zone B1 in 12 hips (16.2%), and at zone B2 in seven hips (9.5%). The final follow-up radiographs, however, revealed only one hip to have a gap of 1.1 mm at zone B2; the majority of the gaps had disappeared. The results suggest that immediate weight-bearing walking did not result in the migration of the cementless acetabular component.

Acetabulum↗
PubMed2006

Interfacial behaviour of strontium-containing hydroxyapatite cement with cancellous and cortical bone.

The bone-bonding behaviors of various biomaterials have been extensively investigated. However, the precise mechanisms of bone bonding have not yet been clarified, and the differences in interfacial behaviors of biomaterial bonding with cancellous bone and cortical bone have not yet been understood. In this study, strontium-containing hydroxyapatite (Sr-HA) cement, in which 10% calcium ions were substituted by strontium, was performed in a rabbit hip replacement model. Six months later, the morphology and chemical composition of interfaces between Sr-HA cement with cancellous bone and cortical bone were evaluated by field emission scanning electron microscopy (FESEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Remarkable differences between these two interfaces were suggested both in morphology and chemical compositions. An apatite layer was found between Sr-HA cement and cancellous bone with a thickness of about 70 microm. However, only a very thin interface (about 1 microm) was formed with cortical bone. As for the cancellous bone/cement interface, high ions intensity of Ca, P, Sr, Na, and O were confirmed by FESEM-EDX and ToF-SIMS. Differences in morphology and chemical component between these two interfaces provided convincing evidences for the proposed dissolution-precipitation coupling mechanism in the formation of biological apatite.

Animals↗
PubMed2006

Strontium-containing hydroxyapatite bioactive bone cement in revision hip arthroplasty.

Clinical outcome of cemented implants to revision total hip replacement (THR) is not as satisfactory as primary THR, due to the loss of bone stock and normal trabecular pattern. This study evaluated a bioactive bone cement, strontium-containing hydroxyapatite (Sr-HA) bone cement, in a goat revision hip hemi-arthroplasty model, and compared outcomes with polymethylmethacrylate (PMMA) bone cement. Nine months after operation, significantly higher bonding strength was found in the Sr-HA group (3.36+/-1.84 MPa) than in the PMMA bone cement group (1.23+/-0.73 MPa). After detached from the femoral component, the surface of PMMA bone cement mantle was shown relatively smooth, whereas the surface of the Sr-HA bioactive bone cement mantle was uneven, by SEM observation. EDX analysis detected little calcium and no phosphorus on the surface of PMMA bone cement mantle, while high content of calcium (14.03%) and phosphorus (10.37%) was found on the surface of the Sr-HA bone cement mantle. Even higher content of calcium (17.37%) and phosphorus (10.84%) were detected in the concave area. Intimate contact between Sr-HA bioactive bone cement and bone was demonstrated by histological and SEM observation. New bone bonded to the surface of Sr-HA cement and grew along its surface. However, fibrous tissue was observed between PMMA bone cement and bone. The results showed good bioactivity of Sr-HA bioactive bone cement in this revision hip replacement model using goats. This in vivo study also suggested that Sr-HA bioactive bone cement was superior to PMMA bone cement in terms of bone-bonding strength. Use of bioactive bone cement may be a possible solution overcoming problems associated with the use of PMMA bone cement in revision hip replacement.

Animals↗
PubMed2006

Strontium-containing hydroxyapatite (Sr-HA) bioactive cement for primary hip replacement: an in vivo study.

The purpose of this study was to evaluate the strontium-containing hydroxyapatite (Sr-HA) cement in primary hip replacement, using a rabbit model, and to investigate the histological findings at the cement-implant and bone-cement interfaces under weight-bearing conditions. Unilateral hip replacement was performed with Sr-HA cement or polymethylmethacrylate (PMMA) cement in rabbits and observations were made after 6 months. Good fixation between the Sr-HA cement and implant was observed. Osseointegration of the Sr-HA cement with cancellous bone was widespread. Many multinucleus cells covered the surface of the cement, and resorbed the superficial layer of the cement. By scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis, high calcium and phosphorus levels were detected at the interface with a thickness of about 10 microm. Intimate contact was also observed between the Sr-HA cement and cortical bone without fibrous layer intervening. The overall affinity index of bone on Sr-HA cement was (85.06 +/- 5.40)%, which is significantly higher than that on PMMA cement (2.77%+/- 0.49%). On the contrary, a fibrous layer was consistently observed between PMMA cement and bone, and PMMA cement evoked an inflammatory response and foreign body reaction in the surrounding bony tissues. Results suggested good bioactivity and bone-bonding ability of the Sr-HA cement under weight-bearing conditions.

Animals↗
PubMed2006

Nano-structural bioactive gradient coating fabricated by computer controlled plasma-spraying technology.

The poor mechanical property of hydroxyapatite was the major problem for load bearing and implant coating in clinical applications. To overcome this weakness, a bioactive gradient coating with a special design composition of hydroxyapatite (HA), ZrO2, Ti, bioglass was developed. This 120 microm coating with an upper layer of 30-50 microm porous HA produced by computer controlled plasma spraying which maintained energy level of the plasma which ensure proper melting of powder. The crystal size of the coating was 18.6-26.2 nm. Transformation of t-ZrO2 to m-ZrO2 reduced the thermal stress that weakened the coating and lowered down interfacial strength of the coating and metal substrate. Thermal stress of sprayed coating was 16.4 MPa which was much smaller than the sample without thermal treatment of 67.1 MPa. Interfacial strength between the coating and metal substrate was 53 MPa which is much higher than conventional Hydroxyapatite coating. Based on XRD analysis crystallinity of HA approached 98%. Therefore, high temperature treatment improved long term stability of the coating through improved crystallinity of hydroxyapatite and reduced other impure calcium phosphate phase.

Aluminum Oxide↗
PubMed2006

Assessment of the proximal femoral morphology using plain radiograph-can it predict the bone quality?

We evaluated the relationship between the radiological indices that assessed the proximal femoral morphology and the degree of osteoporosis in 45 Chinese cadaveric femora. Canal-calcar ratio, canal flare index, morphological cortical index, and canal bone ratio were determined in the plain anteroposterior radiographs. Canal bone ratio is the ratio between the endosteal and outer diameters of the proximal femur at 10 cm below the lesser trochanter. Bone mineral density of the proximal femora was measured with dual-energy x-ray absorptiometry, and T score that depicted the degree of osteoporosis was determined. Canal bone ratio showed a strong correlation with the T score (r = -0.71, P < .001) and the best overall performance in diagnosing osteoporosis with receiver operating characteristic curve analysis. The proximal femur was likely to be osteoporotic if the canal bone ratio was 0.49 or higher.

Absorptiometry, Photon↗
PubMed2005

Nano-mechanics of bone and bioactive bone cement interfaces in a load-bearing model.

Many bioactive bone cements were developed for total hip replacement and found to bond with bone directly. However, the mechanical properties at the bone/bone cement interface under load bearing are not fully understood. In this study, a bioactive bone cement, which consists of strontium-containing hydroxyapatite (Sr-HA) powder and bisphenol-alpha-glycidyl dimethacrylate (Bis-GMA)-based resin, was evaluated in rabbit hip replacement for 6 months, and the mechanical properties of interfaces of cancellous bone/Sr-HA cement and cortical bone/Sr-HA cement were investigated by nanoindentation. The results showed that Young's modulus (17.6+/-4.2 GPa) and hardness (987.6+/-329.2 MPa) at interface between cancellous bone and Sr-HA cement were significantly higher than those at the cancellous bone (12.7+/-1.7 GPa; 632.7+/-108.4 MPa) and Sr-HA cement (5.2+/-0.5 GPa; 265.5+/-39.2 MPa); whereas Young's modulus (6.3+/-2.8 GPa) and hardness (417.4+/-164.5 MPa) at interface between cortical bone and Sr-HA cement were significantly lower than those at cortical bone (12.9+/-2.2 GPa; 887.9+/-162.0 MPa), but significantly higher than Sr-HA cement (3.6+/-0.3 GPa; 239.1+/-30.4 MPa). The results of the mechanical properties of the interfaces were supported by the histological observation and chemical composition. Osseointegration of Sr-HA cement with cancellous bone was observed. An apatite layer with high content of calcium and phosphorus was found between cancellous bone and Sr-HA cement. However, no such apatite layer was observed at the interface between cortical bone and Sr-HA cement. And the contents of calcium and phosphorus of the interface were lower than those of cortical bone. The mechanical properties indicated that these two interfaces were diffused interfaces, and cancellous bone or cortical bone was grown into Sr-HA cement 6 months after the implantation.

Animals↗
PubMed2005

Residual posterior femoral condyle osteophyte affects the flexion range after total knee replacement.

We followed up 92 patients with total knee replacement and a pre-operative knee flexion of at least 90 degrees . The patients were followed up regularly at 3 months, 6 months and 1 year. The outcome measured was the amount of maximum passive knee flexion at the end of 1 year after replacement. The potential factors affecting the final flexion range were investigated. After regression analysis, apart from pre-operative knee flexion (p<0.001), the most significant independent surgical factors that predict the amount of post-operative flexion were presence of residual posterior femoral condyle osteophyte (p=0.046) and overstuffing the patella by more than 2 mm during resurfacing of the patella (p<0.001).

Aged↗
PubMed2005

Evolution of surface roughness of some metallic materials in cavitation erosion.

The evolution of surface roughness of three common metallic materials (316L stainless steel, CP titanium, and brass) in ultrasonic vibratory cavitation tests was monitored using profilometric measurements. Three stages of roughness change, based on the rate of change of the mean surface roughness d(Ra)/dt, may be identified. In stage I (initial stage), Ra increases almost linearly with the test time; in stage II (transition stage), the rate decreases until stage III (steady-state stage) is reached, in which Ra remains unchanged. Concurrent measurements of mass loss in the ultrasonic cavitation test indicated that stage I approximately coincides with the incubation stage, stage II approximately coincides with the acceleration stage, and stage III approximately coincides with the maximum erosion rate stage as defined by ASTM Standard G 32. Compared with conventional mass loss measurements in assessing material degradation in cavitation erosion, surface roughness measurements provide an alternative and convenient method which possesses several advantages. In the first place, change in surface roughness provides information of material response before mass loss is detected. Secondly, there is no restriction of the size of the component, while weighing is suitable for small samples only. Thirdly, mass loss reflects erosion of the whole surface under cavitation attack, and the mean depth of penetration or erosion only gives an average loss, while in roughness measurement, damage in specific locations may be studied. The present study indicates that roughness measurement may constitute a practical method for monitoring damage in industrial ultrasonic cleaners.

Chemical Phenomena↗
PubMed2005

Intraobserver errors in obtaining visually selected anatomic landmarks during registration process in nonimage-based navigation-assisted total knee arthroplasty: a cadaveric experiment.

This study investigated the intraobserver errors in obtaining visually selected anatomic landmarks that were used in registration process in a nonimage-based computer-assisted total knee replacement (TKR) system. The landmarks studied were center of distal femur, medial and lateral femoral epicondyle, center of proximal tibia, medial malleolus, and lateral malleolus. Repeated registration in the above sequence was done for 100 times by a single surgeon. The maximum combined errors in the mechanical axis of the lower limb were only 1.32 degrees (varus/valgus) in the coronal plane and 4.17 degrees (flexion/extension) in the sagittal plane. The maximum error in transepicondylar axis was 8.2 degrees. The errors using the visual selection of anatomic landmarks for the registration technique of bony landmarks in nonimage-based navigated TKR did not introduce significant error in the mechanical axis of the lower limb in the coronal plane. However, the error in the transepicondylar axis was significant in the "worst-case scenario."

Arthroplasty, Replacement, Knee↗
PubMed2005

Sagittal bowing of the distal femur in Chinese patients who require total knee arthroplasty.

PURPOSES: The importance of the femoral sagittal bowing on total knee arthroplasty is under-recognized. The bowing could lead to potential errors in positioning of the femoral component if it is ignored. We aimed to document the femoral sagittal bowing at different segments of the Chinese femur and to discuss the implications of this sagittal bowing on total knee arthroplasty. METHODS: One hundred lateral radiographs of the entire lower limbs of 85 Chinese patients admitted for total knee arthroplasty were digitized. The radii of curvature of the intramedullary canal of the proximal, middle and distal one-third of the femora were measured. RESULTS: The average age of the patients was 67.3 years. The radii of curvature of the proximal, middle and distal one-third of the femora were 1081.6, 926.2 and 715.1 mm, respectively. The distal one-third of the femora was significantly more bowed than the other parts of the femora (p<0.001). The distal femoral bowing was more profound in rheumatoid patients and in those with a short femur. CONCLUSIONS: The lateral contour of the Chinese femur is like a hockey stick. This exaggerated sagittal bowing in the Chinese femur can affect the final sagittal position of the femoral component and has implications for the choice of implant design. In revision setting, a long and straight press-fit stem might either endanger the anterior cortex or deflect the femoral component to an abnormally extended position.

Adult↗
PubMed2005

A novel artificial prosthetic replacement for the proximal interphalangeal joint of the hand--from concept to prototype.

This article describes the development of a proximal interphalangeal (PIP) joint prosthesis based on the principles of replicating anatomical surface components, the use of macrolocking intramedullary stem and the use of a cobalt-chrome alloy material. The design features are intended to obtain an optimal range of motion while retaining stability and longevity. The final prototype, for which a patent has been filed, is described.

Chromium Alloys↗
PubMed2005

Cemented or uncemented femoral component in primary total hip replacement? A review from a clinical and radiological perspective.

Controversy exists regarding the optimal method of fixation for primary total hip replacement, particularly the femoral component. We performed a systematic literature review to explore whether cemented total hip replacement can achieve better clinical and radiological outcomes. A total of 29 publications were selected using computer-aided and manual searches. A qualitative comparison of results in clinical and radiological changes was then conducted. Most of the literature showed that better short-term clinical and functional outcomes could be obtained from cemented femoral fixation than from uncemented femoral fixation. Results were less clear for the mid-term clinical outcome, though in general, cemented fixation still appeared to show a superior clinical outcome. Radiographic differences are variable and do not seem to correlate with clinical findings. For the short- and mid-term, cemented femoral component is recommended. However, a long-term randomised trial combined with a large cohort study or registry is needed.

Arthroplasty, Replacement, Hip↗
PubMed2004

Translation and validation of Arthritis Impact Measurement Scales 2 into Chinese: CAIMS2.

OBJECTIVE: To evaluate the validity, reliability, and cultural relevance of the Arthritis Impact Measurement Scales 2 (AIMS2) as a health assessment tool for Chinese-speaking patients with arthritis. METHODS: The cultural relevance, language equivalency, and content validity of the AIMS2, Chinese version (CAIMS2) were evaluated by an expert panel. Measurement performance was tested on 240 subjects (rheumatoid arthritis = 81, osteoarthritis = 77, healthy = 82). Subjects (n = 175) were retested within 2 weeks for testing of reliability. RESULTS: Three items were modified and 2 items were added, as suggested by the expert panel. Interitem reliability was satisfactory (intraclass correlation coefficient 0.8552-0.9594). Test-retest reliability of the CAIMS2 subscales ranged from 0.770 to 0.952 in subjects in whom the CAIMS2 was self administered. Significant score differences between patients with arthritis and healthy subjects were found in all 12 subscales, except for the support from family and friends and tension subscales. CAIMS2 subscale scores correlated with clinical and laboratory measures of disease activity and patients' perceived quality of life as measured using the Chinese version of the World Health Organization Quality of Life instrument. CONCLUSION: Empirical data support CAIMS2 is a valid and reliable health status measure for Chinese speaking patients with arthritis.

Activities of Daily Living↗
PubMed2004

Posterior cruciate ligament-substituting total knee arthroplasty in young rheumatoid patients with advanced knee involvement.

The integrity and strength of the posterior cruciate ligament (PCL) in the rheumatoid knee are known to be suboptimal. However, the results of PCL-substituting total knee arthroplasty in rheumatoid patients are not well documented. We reviewed 86 PCL-substituting total knee arthroplasties in 52 rheumatoid patients with grade IV or V radiographic disease. The mean age at surgery was 41.9 years. All patients underwent follow-up evaluation for an average of 7.8 years. Revision was performed for 1 knee because of aseptic loosening of the tibial component, and for 3 knees because of deep infection. An isolated insert exchange was performed on one knee. Using revision of any component for aseptic loosening or radiographic loosening as the end point, the mean 10-year survival rate was 94.0%.

Actuarial Analysis↗
PubMed2004

Distal rotational alignment of the Chinese femur and its relevance in total knee arthroplasty.

The rotational alignments of the distal femur in southern Chinese subjects were investigated. Chinese femurs are significantly more externally rotated. This is new evidence to suggest a racial difference in the distal femoral geometry. During total knee arthroplasty, a common recommendation is to allow 4 degrees of external rotation. The clinical significance of our study is that this need to be modified to 6 degrees for Chinese women and 5 degrees for Chinese men. This racial difference can be incorporated into a new concept of "a mountain and a molehill." This concept is presented in this report.

Adolescent↗
PubMed2004

Critical radiological analysis after Austin Moore hemiarthroplasty.

The aim of this study is to investigate the causes of prosthesis loosening in patients treated with Austin Moore hemiarthroplasty (AMA). The clinical and radiological outcomes were documented in a quantitative manner after 7 years follow-up of 144 patients. At the time of final follow-up, 52 patients had died and 48 patients were lost to follow-up, leaving a total of 44 patients for analysis. Immediate post-operative X-rays were studied for the initial alignment of prosthesis, the fit of the prosthesis and the degree of osteoporosis. X-rays on latest follow-up were studied for evidence of loosening. All patients were assessed clinically with the hip score of hospital for special surgery. It was found that hip pain was significantly related to subsidence and pivoting of the prosthesis (P = 0.014 and 0.035, respectively). Significant increase in subsidence was noted if the stem of prosthesis was not fitting well within the shaft of femur (P = 0.006). When the patient was younger than 73 years old at the time of operation, there was more subsidence of the prosthesis at the final follow-up (P = 0.001). It was concluded that the fill of AMA within the shaft of femur should be greater than 70% to avoid early loosening. Relatively younger patients with acute fracture of the neck of femur should be treated by methods other than cementless AMA.

Age Factors↗