A novel rapid prototyping and finite element method-based development of the patient-specific temporomandibular joint implant.

OBJECTIVE: The objective of this study was to fabricate a successful implant for temporomandibular joint (TMJ) disorder patients who could not be treated through conventional surgeries. METHODS: A custom-made implant was fabricated using rapid prototyping (RP) for the TMJ surgery. The stability of the metallic implant was validated using a finite element analysis. RESULTS: The results of finite elements were stable and the design of the TMJ implant was suitable as per the patient's need. The customised implant was made using a fused deposition modelling method of RP and a vertical machining centre. The implant has provided normal jaw function for over 2 years since surgery. CONCLUSIONS: The approach utilised will be helpful in providing successful treatment to the deformed mandible and the mandible joints. This method allows to customise and to accurately fabricatie the implant. Advantages of this approach are that the physical model of the implant was tested for stability before the implantation, the surgeon can plan and rehearse the surgery in advance, it is a less invasive and less time-consuming surgical procedure.

Design and manufacturing of customised femoral stems for the Indian population using rapid manufacturing: a finite element approach.

Joint replacement surgeries in India primarily involve the use of conventional implants, also referred to as 'standard implants'. There has been a little awareness about the possibility of using customised implants for such surgeries. Although standard implants from various biomedical companies are easily available in the Indian market, they are expensive and rarely conform to patient's anatomy. Studies in the past have shown that there are anatomical variations in the hip joint for different ethnic backgrounds and geographical locations. This article evaluates the feasibility of using custom-manufactured hip implants and presents a comparison between the former and standard implant from stress reduction point of view. Two CAD models of femoral stems - one from standard sized hip implant available in the market and other from customised hip implant designed as per parameters from a radiograph (specific to the patient's anatomy) - are used for evaluation. Finite element analysis was carried out for a double-legged stance. The comparative study indicated lesser stresses in head and neck region of the customised femoral stems than the standard implant. The study suggests design feasibility of customised implants for the Indian population owing to reduction in stresses in the implant.

Preplanning and simulation of surgery using rapid modelling.

Rapid prototyping (RP) is increasingly being used for solution of many problems associated with biomedical engineering. RP quickly delivers prototypes that are constructed in an additive, layer-by-layer process driven by three-dimensional computer aided design (CAD) data. The aim of this work was to demonstrate that surgery for acetabulum fracture can be significantly facilitated through the use of a method based on advanced imaging techniques and the RP technique. A case of complex acetabulum fracture was reported, and application of computed tomography (CT) images, CAD and RP were explored. Modelling of the fractured part helped in preplanning and simulating the surgery and saved surgery time. The method allowed feedback action at most steps of the surgery process, thus permitting an important time saving during surgery.

Evaluation of human (genotype 1) and swine (genotype 4)-ORF2-based ELISAs for anti-HEV IgM and IgG detection in an endemic country and search for type 4 human HEV infections.

Open reading frame 2 proteins (ORF2) from swine (genotype 4, S-ORF2) and human (genotype 1, H-ORF2) hepatitis E virus (HEV) having 91.4% identity at amino acid level were expressed using baculovirus expression system. Comparison of ELISAs based on the two proteins yielded identical results when sequential serum samples from monkeys and pigs experimentally infected with genotypes 1 and 4 HEV, respectively, were tested. Samples from patients (n = 258) suffering from non-A, non-B hepatitis during outbreaks of the disease and 180 sera from apparently healthy children were screened by H-ORF2-, S-ORF2-based ELISAs and Genelabs ELISA, a widely used commercial test for HEV diagnosis. Specificity of all three tests in detecting IgM and IgG antibodies in healthy children was comparable. Excellent correlation was noted in detecting both IgM (98.7% concordance) and IgG (97.7% concordance) anti-HEV antibodies when H-ORF2 and S-ORF2 ELISAs were compared. When compared with Genelabs ELISA, both H-ORF2 and S-ORF2 ELISAs identified 34 and 18 additional positives, respectively, in IgM and IgG anti-HEV tests showing comparatively less sensitivity of the commercial assay. The concordance of Genelabs ELISA in IgM detection was 86.4% and 85.6%, respectively, with H-ORF2 and S-ORF2 ELISAs. The concordance between Genelabs ELISA and H-ORF2 decreased further to 73.6% when 129 human samples from recent HEV epidemics (2002-2004) were tested for IgM. Similar results were obtained when sequential samples from 11 hepatitis E patients were examined. Screening of serum samples from 137 sporadic non-A, non-B hepatitis cases further confirmed the superiority of the H-ORF2 and S-ORF2 ELISAs. All 36/137 HEV-RNA-positive samples from sporadic cases belonged to genotype 1 confirming absence/rarity of type 4 human infections. H-ORF2 and S-ORF2 antigens were swappable in ELISAs for detecting both genotypes 1 and 4 HEV infections.

Hepatitis G virus infection in India: prevalence and phylogenetic analysis based on 5' non-coding region.

OBJECTIVES: To determine the prevalence of hepatitis G virus (HGV) infection in western India and to carry out phylogenetic analysis of HGV isolates. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) assay was used to detect HGV RNA in serum samples obtained from paid plasma donors, patients with hemophilia and voluntary blood donors. Nine Indian and one Kenyan HGV RNA-positive samples were sequenced in the 5' non-coding region (5'-NCR). Phylogenetic analysis based on the comparison of a 101 nucleotide fragment from a large number of HGV isolates from 22 countries (including Indian and Kenyan sequences obtained during the present study) was carried out. RESULTS: HGV RNA positivity rates among paid plasma donors from a commercial plasmapheresis unit (7/43, 16.3%) and patients with hemophilia (5/44, 11.4%) were significantly higher than that in voluntary blood donors (0/51; p=0.003 and 0.019, respectively). Among patients with acute non-A to E hepatitis and fulminant hepatic failure, 1 of 50 and 1 of 28 were HGV RNA-positive, whereas 6 of 49 (12%) patients with chronic liver disease had circulating HGV RNA. All Indian isolates belonged to genotype 2, whereas the Kenyan isolate formed a distinct branch within genotype 1 consisting of African isolates. CONCLUSION: Our results suggest existence of parenteral transmission of HGV in the Indian population. HGV was not an important cause of acute non-A to E hepatitis or fulminant hepatic failure among the patients investigated. Genotype 2 seems to be the most prevalent genotype in western India.

Prevalence and phylogenetic analysis of TT virus DNA in Western India.

In western India, TT virus (TTV) DNA positivity varied from 6.7% (5 of 75) in chronic hepatitis patients to 24.4% (10 of 41) in hemophiliacs; 7.4% (4 of 54) of voluntary blood donors had circulating TTV DNA. Phylogenetic analysis revealed a predominance of genotype 1a. In India, TTV is transmitted mainly by nonparenteral routes and is not an important cause of chronic liver diseases.