The influence of the strength of bone on the deformation of acetabular shells: a laboratory experiment in cadavers.

Concerns have been raised that deformation of acetabular shells may disrupt the assembly process of modular prostheses. In this study we aimed to examine the effect that the strength of bone has on the amount of deformation of the acetabular shell. The hypothesis was that stronger bone would result in greater deformation. A total of 17 acetabular shells were inserted into the acetabula of eight cadavers, and deformation was measured using an optical measuring system. Cores of bone from the femoral head were taken from each cadaver and compressed using a materials testing machine. The highest peak modulus and yield stress for each cadaver were used to represent the strength of the bone and compared with the values for the deformation and the surgeon's subjective assessment of the hardness of the bone. The mean deformation of the shell was 129 µm (3 to 340). No correlation was found between deformation and either the maximum peak modulus (r² = 0.011, t = 0.426, p = 0.676) or the yield stress (r² = 0.024, t = 0.614, p = 0.549) of the bone. Although no correlation was found between the strength of the bone and deformation, the values for the deformation observed could be sufficient to disrupt the assembly process of modular acetabular components.

Analysis of failed Van Straten LPM proximal interphalangeal prostheses.

The two-piece Van Straten Leuwen Poeschmann Metal (LPM) prosthesis was intended for the proximal interphalangeal joints. However, revision rates of 29% after 19 months were reported, as well as massive osteolysis. Five failed LPM titanium-niobium coated cobalt chromium components were obtained, three distal and two proximal, and subjected to a forensic retrieval analysis. Components were analyzed using a Talysurf contacting profilometer, ZYGO noncontacting profilometer, and environmental-scanning electron microscope. All components were heavily worn. In some regions the titanium-niobium coating had been scratched and penetrated. Elsewhere this coating had been removed where there was minimal scratching, which may have been due to corrosion between the coating and substrate. The osteolysis reported clinically was likely to be linked to the wear debris from the failed titanium-niobium coating and substrate.

Combined chemotherapy and radiotherapy for esophageal carcinoma in a hemodialyzed patient. Long-term survival.

The use of antimitotic chemotherapy in hemodialysis patients is not yet well codified, and each individual decision remains difficult. We report the case of a 68-year-old hemodialyzed man who developed a squamous cell carcinoma of the upper third of the esophagus. Necessarily disabling surgery was rejected, and three courses of combined radio- and chemotherapy with 5-fluorouracil and cis-platinum were performed without decreasing standard doses. The percentage of drugs removed during hemodialysis sessions was low; peak and residual platinum plasma concentrations were only slightly above those observed in normal renal function patients. The treatment was perfectly well tolerated, and tumor response was satisfactory without any relapse for 3 years. This observation suggests that hemodialysis patients could benefit from such 'full therapies', if necessary, without major adverse effects.

Results of endocavitary irradiation of early rectal tumors.

At the C. G. F. Leclerc, Dijon, 91 early rectal tumors were treated with intracavitary contact radiotherapy alone or in combination with interstitial brachytherapy. The median age of the patients was 70 years. Most of them were referred because of poor surgical risk. Preservation of the sphincter was obtained in 85% (77/91). The actuarial local relapse-free survival rate at 5 years was 74% (67/91). No significant difference was seen between the 72 adenocarcinomas and 19 villous adenomas (p = 0.12). For the middle rectum the rate was 94% compared to 54% for the upper and 77% for the lower rectum. Anterior primaries fared better than posterior and lateral tumors (100%, 63%, and 67% respectively). After salvage therapy the local control rate raised to 91% (83/91). The clinical and endoscopic staging system of Dijon was of prognostic significance: T1A adenocarcinomas (purely exophytic tumors of less than 3 cm) had a better 5-year local relapse-free survival rate (97%) than T2A, T1B or T2B (p less than 0.01).

Dental preservation in patients irradiated for head and neck tumours: A 10-year experience with topical fluoride and a randomized trial between two fluoridation methods.

Since 1972, the dentures of 935 patients irradiated for head and neck carcinoma have been preserved after careful selection and according to well-defined criteria, using a prospective programme of daily applications of topical sodium fluoride gel. The results of 1-10 years follow-up are given. Four percent of the patients developed a diffuse dental decay and 1% a bone necrosis which can be related to the dental preservation. None of these complications occurred with careful patient selections nor when programme compliance was maintained. Post-irradiation dental extractions were performed in 29 cases with subsequent healing in all cases but one. The surgical technique of such extractions is described. In March 1980, a randomized protocol was activated to compare the use of the sodium fluoride gel to high content fluoride toothpaste (1350 ppm F-). Two hundred and twenty patients were entered. At 12-36 months follow-up, dental caries were observed in 3% of the patients receiving the fluoride gel as compared to 11% receiving the toothpaste (p = 0.1). However, none of the patients adhering to the programme instructions failed in either arm. Currently, it seems reasonable to state that preservation of teeth in irradiated patients should be the rule and not the exception, given good dental condition prior to treatment and patient cooperation. The 5 min daily application of fluoride gel is the most reliable method for prevention of post-irradiation dental caries. The twice daily use of high content fluoride toothpaste is a good alternative provided its limitations are well understood by the clinician and patient.