PubMed · 7800600
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M A Ritter. 1994. Cemented all-poly cups.. https://doi.org/10.3928/0147-7447-19940901-14
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Differential scanning calorimetry (DSC) was used to examine thermal and thermooxidative properties of ultrahigh molecular weight polyethylene (UHMW-PE) of five acetabular components of failed orthopedic implants retrieved at revision of total hip arthoplasty. The results were compared with controls (unimplanted acetabular cups, a 20-year-old slab of UHMW-PE, and raw material). Profiles of exothermic peaks indicated increased levels of oxidation in all retrieved cups. In three retrieved cups, DSC revealed an additional peak of endotherm that was not seen in control samples. The additional endotherm peaks were not artifacts due to oxidation during scanning, heat buildup during cutting of the samples, or the sterilization method after retrieval. The additional peak was associated with the bulk of the polymer that was extracted with hexane. It varied in relative area, depending on its original location of the sample in a cup, implicating local variability in the extent of changes in material property. The distribution of the changes suggests that, during implantation, tissue exposure and friction affected the level of oxidation and degree of crystallinity in the UHMW-PE to a greater degree than did loading alone. Overall results showed that DSC may be a useful tool in evaluating changes in the properties of UHMW-PE orthopedic components in vivo.
Fractures of the posterior wall of the acetabulum form a special group in acetabular fractures. This study aims to evaluate the results in the management of such fractures. Thirty-two patients with fractures of posterior wall of acetabulum were reviewed retrospectively. The follow-up period was 7 (range 3-10) years. Twenty-four were associated with initial posterior dislocations. Twenty-seven were managed with open reduction and internal fixation, while the remainder were managed conservatively. Reductions were rated as congruent in 30 cases and as noncongruent in 2. The functional results were excellent in 16 cases, good in 10, fair in 2, and poor in 4. Two early complications were met, namely 1 iatrogenic sciatic nerve injury and 1 superficial wound infection. Sixteen late complications were noted, including 10 heterotopic ossifications, 3 avascular necroses of femoral head, and 3 symptomatic arthritides. The incidence of late complications was high, but the functional results were generally satisfactory. Congruent reduction was the key in obtaining satisfactory results in the management of these fractures.