Search tips
Search criteria

Results 1-3 (3)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Quantifying subtle but persistent peri-spine inflammation in vivo to submicron cobalt–chromium alloy particles 
European Spine Journal  2012;21(12):2649-2658.
We evaluated the consequences of cobalt–chromium alloy (CoCr) wear debris challenge in the peri-spine region to determine the inflammation and toxicity associated with submicron particulates of CoCr-alloy and nickel on the peri-spine.
The lumbar epidural spaces of (n = 50) New Zealand white rabbits were challenged with: 2.5 mg CoCr, 5.0 mg CoCr, 10.0 mg CoCr, a positive control (20.0 mg of nickel) and a negative control (ISOVUE-M-300). The CoCr-alloy and Ni particles had a mean diameter of 0.2 and 0.6 μm, respectively. Five rabbits per dose group were studied at 12 and 24 weeks. Local and distant tissues were analyzed histologically and quantitatively analyzed immunohistochemically (TNF-α and IL-6).
Histologically, wear particles were observed in all animals. There was no evidence of toxicity or local irritation noted during macroscopic observations in any CoCr-dosed animals. However, Ni-treated control animals experienced bilateral hind leg paralysis and were euthanized at Day 2. Histopathology of the Ni particle-treated group revealed severe neuropathy. Quantitative immunohistochemistry demonstrated a CoCr-alloy dose-dependent increase in cytokines (IL-6, TNF-α, p < 0.05) at 12 and 24 weeks.
Subtle peri-spine inflammation associated with CoCr-alloy implant particles was dose dependent and persistent. Neuropathy can be induced by highly reactive Ni particles. This suggests peri-spine challenge with CoCr-alloy implant debris (e.g., TDA) is consistent with past reports using titanium alloy particles, i.e., mild persistent inflammation.
PMCID: PMC3508226  PMID: 22407269
Spine; Osteolysis; Particles; Implant debris; Total disc arthroplasty; Cobalt–chromium alloy; Cytokines; Biological response
2.  Comparison of in vivo and simulator-retrieved metal-on-metal cervical disc replacements 
Cervical disc arthroplasty is regarded as a promising treatment for myelopathy and radiculopathy as an alternative to cervical spine fusion. On the basis of 2-year clinical data for the PRESTIGE® Cervical Disc (Medtronic, Memphis, Tennessee), the Food and Drug Administration recommended conditional approval in September 2006 and final approval in July 2007; however, relatively little is known about its wear and damage modes in vivo. The main objective was to analyze the tribological findings of the PRESTIGE® Cervical Disc. This study characterized the in vivo wear patterns of retrieved cervical discs and tested the hypothesis that the total disc replacements exhibited similar surface morphology and wear patterns in vitro as in vivo.
Ten explanted total disc replacements (PRESTIGE®, PRESTIGE® I, and PRESTIGE® II) from 10 patients retrieved after a mean of 1.8 years (range, 0.3–4.1 years) were analyzed. Wear testing included coupled lateral bending ( ±4.7°) and axial rotation ( ±3.8°) with a 49 N axial load for 5 million cycles followed by 10 million cycles of flexion-extension ( ±9.7°) with 148 N. Implant surfaces were characterized by the use of white-light interferometry, scanning electron microscopy, and energy dispersive spectroscopy.
The explants generally exhibited a slightly discolored, elliptic wear region of varying dimension centered in the bearing center, with the long axis oriented in the medial-lateral direction. Abrasive wear was the dominant in vivo wear mechanism, with microscopic scratches generally oriented in the medial-lateral direction. Wear testing resulted in severe abrasive wear in a curvilinear fashion oriented primarily in the medial-lateral direction. All retrievals showed evidence of an abrasive wear mechanism.
This study documented important similarity between the wear mechanisms of components tested in vitro and explanted PRESTIGE® Cervical Discs; however, the severity of wear was much greater during the in vitro test compared with the retrievals.
PMCID: PMC4300870
Cervical arthroplasty; Total disc replacement; Biomechanics; Retrieval analysis
3.  Public perception on the role of community pharmacists in self-medication and self-care in Hong Kong 
The choices for self-medication in Hong Kong are much diversified, including western and Chinese medicines and food supplements. This study was to examine Hong Kong public knowledge, attitudes and behaviours regarding self-medication, self-care and the role of pharmacists in self-care.
A cross-sectional phone survey was conducted, inviting people aged 18 or older to complete a 37-item questionnaire that was developed based on the Thematic Household surveys in Hong Kong, findings of the health prorfessional focus group discussions on pharmacist-led patient self management and literature. Telephone numbers were randomly selected from residential phone directories. Trained interviewers invited eligible persons to participate using the "last birthday method". Associations of demographic characteristics with knowledge, attitudes and beliefs on self-medication, self-care and role of pharmacists, and spending on over-the-counter (OTC) products were analysed statistically.
A total of 1, 560 phone calls were successfully made and 1, 104 respondents completed the survey which indicated a response rate of 70.8%. 63.1% had adequate knowledge on using OTC products. Those who had no formal education/had attended primary education (OR = 3.19, 95%CI 1.78-5.72; p < 0.001), had attended secondary education (OR = 1.50, 95%CI 1.03-2.19; p = 0.035), and aged ≥60 years (OR = 1.82, 95% CI 1.02-3.26; p = 0.042) were more likely to have inadequate knowledge on self-medication. People with chronic disease also tended to spend more than HKD100 on western (OR = 3.58, 95%CI 1.58-8.09; p = 0.002) and Chinese OTC products (OR = 2.94, 95%CI 1.08-7.95; p = 0.034). 94.6% believed that patients with chronic illnesses should self-manage their diseases. 68% agreed that they would consult a pharmacist before using OTC product but only 45% agreed that pharmacists could play a leading role in self-care. Most common reasons against pharmacist consultation on self-medication and self-care were uncertainty over the role of pharmacists and low acceptance level of pharmacists.
The majority of respondents supported patients with chronic illness to self-manage their diseases but less than half agreed to use a pharmacist-led approach in self-care. The government should consider developing doctors-pharmacists partnership programs in the community, enhancing the role of pharmacists in primary care and providing education to patients to improve their awareness on the role of pharmacists in self-medication and self-care.
PMCID: PMC3252282  PMID: 22118309

Results 1-3 (3)