PubMed · 11003085
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F G Alvine. 2000. Modified operating table for knee surgery.. https://doi.org/10.3928/0147-7447-20000901-10
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trans-Vinylene unsaturations generated in ultrahigh-molecular-weight polyethylene (UHMWPE) after radiation treatment scales linearly with the absorbed dose level, and can serve as an internal dosimeter for determining the radiation dose level for sterilizing or crosslinking UHMWPE. We measured the trans-vinylene concentration using infrared spectroscopy and generated calibration curves for ultrahigh-molecular-weight polyethylene (ram-extruded GUR 1050) after cold e-beam, cold gamma, and warm e-beam irradiations. The trans-vinylene content increased linearly with the absorbed dose level in all cases except with cold gamma irradiation at dose levels higher than approximately 70 kGy. At that dose level the trans-vinylene content of the warm irradiated samples was higher than those of the cold irradiated samples. Following postirradiation melting, the trans-vinylene content of the gamma irradiated samples increased. Such trans-vinylene quantification can be an internal dosimeter for crosslinked UHMWPE when radiation is used for improving its wear resistance or sterilizing the device made thereof. It can also be utilized to assess the spatial uniformity of the absorbed radiation dose level.
We performed a systematic review of the literature to compare the clinical outcomes of the management of three and four part fractures of the proximal humerus by conservative regimes, internal and external fixations and arthroplasty. We identified 147 reports of comparative trials and case series between 1969 and 1999. We selected only studies dealing exclusively with three and four part fractures of the proximal humerus, with at least 15 patients, treated within 48 h of injury by one of the three modalities studied, in which at least one of the outcomes of interest (pain, range of motion, infection and restoration of anatomy) was described. Also, to be included, studies had to have a follow-up period of at least 6 months, in which a minimum of 85% of patients were followed-up. Twenty four reports met our eligibility criteria. Conservatively managed patients had more pain and a poorer range of motion than those managed by either fixation or arthroplasty. Better restoration of anatomy was delivered in the fixation group. There was no significant difference in the functional range of motion between the arthroplasty and fixation groups, but there were very few studies available to compare infection rates in these two management modalities. The results from the present systematic review suggest that the data from the published literature are inadequate for evidence-based decision making with regards to the treatment of complex proximal humeral fractures.
OBJECTIVE: The objective of the present study was to analyze the mechanical effect of some of the surgical variables encountered during shoulder arthroplasty using the finite element method. The effect of one eccentric load case, cement thickness and conformity has been investigated. DESIGN: A 3D finite element model of a healthy cadaveric scapula implanted with an anatomically shaped glenoid has been developed from computed tomography (CT) images. BACKGROUND: Glenoid component fixation can present the most difficult problem in total shoulder arthroplasty, loosening of this component remains one of the main complications. METHODS: The 3D finite element model was first validated by comparison with experimental measurements and by fitting of the mechanical properties of the cortical bone. Then the articular pressure location, the surface contact geometry and the cement thickness have been analyzed to observe their effect on stresses and displacements at the interfaces and within the scapular bone. RESULTS: The antero-posterior bending of the scapula was a notable feature and this was accentuated when an eccentric load was applied. The gleno-humeral contact area had a major role on the stress level in the supporting structures though but not on the global displacements. Varying the cement mantle modified stresses according to the load case and it essentially changed the latero-medial displacement of the cement relatively to the bone. CONCLUSIONS: This analysis provided an insight into the mechanical effects of an implanted scapula according to different parameters related to implantation technique. RELEVANCE: Results emphasized the role of some of the parameters a clinician may face. They demonstrated the importance of the humeral head centering in the horizontal plane. Conformity decreasing may involve drastic increase of stresses within structures and a thick cement mantle is not necessarily advantageous relatively to the stresses at the cement/bone interface.