ABSTRACT
Metallurgical investigation methods were used to determine the cause of failure in a broken and explanted lock pin. Material analysis revealed that the implant material consists of a stainless steel. The fractographic investigation indicated a fatigue fracture with its typical characteristics. Macroscopic damage of the outer surface of the implant caused the fatigue fracture in the bone fracture region. Once the lock pin had failed, further crack propagation of the fatigue fracture was largely dependent on stress intensity and/or overloading of the implant in the bone fracture region as well as on the number of stress cycles. The following items should be observed by the physician applying implant materials: 1. A material showing only very small surface scratches in the order of magnitude of thousands of millimeters should not be implanted at all, because even the smallest surface roughness may cause fractures of the material. 2. Implant materials from low-cost manufacturers should never be applied. Such materials often show construction faults (in the present case an unnecessary weld in the upper part of the lock pin) or the material itself is not well conditioned (in the present case an insufficient annealing treatment).
Subject(s)
Bone Nails/standards , Femoral Fractures/surgery , Hardness Tests , Humans , Male , Metallurgy/methods , Microscopy, Electron, Scanning , Prosthesis Failure , Stress, MechanicalABSTRACT
Cryptosporidiosis species were demonstrated in stool of 1.9% of 1600 unselected patients with enteritis (practically evenly divided between children and adults). Further investigations revealed seven cases of enteritis among family members. In eight patients there was a double infection with Cryptosporidium plus another enteritis pathogen. The most frequent clinical symptoms were diarrhea, vomiting, cramp-like abdominal pain, fever and headache. The mean period of parasite excretion was 14 days. Spontaneous cure occurred in all patients. Since cryptosporidiosis is relatively common not only in those with lowered resistance but also those who are immune-competent, search for Cryptosporidium should be included in all tests for etiologically uncertain cases of enteritis.
