Quantification and localisation of damage in rat muscles after controlled loading; a new approach to study the aetiology of pressure sores

To obtain more insight in the aetiology of deep pressure sores, an animal model was developed to relate controlled externalloading to local muscle damage. The tibialis anterior muscle (TA) and overlying skin of a rat were compressed between indentorand tibia. Loads of 10, 70 and 250 kPa at skin surface were applied for 2 or 6 h. During half of the 10 and 250 kPa experimentsinterstitial fluid pressure (IFP) in the TA was measured. The TAs were excised 24 h after load application. Both amount and locationof damage were assessed by histological examination using a semi-automated image-processing program. In six of eleven loadedmuscles damage was found. The damage was located from superficial to deep muscle tissue in a zone never exceeding the diameterof the inden! tor. The IFP measurements interfered with the occurrence of damage; application of 10 and 70 kPa loads only causeddamage when combined with IFP measurements, whereas IFP measurements increased damage at 250 kPa loads. The results showedthat the developed animal model can be used to provoke local damage by applying a controlled load and that the amount andlocation of damage can be assessed using the newly developed techniques. .2001 IPEM. Published by Elsevier Science Ltd. Allrights reserved.Keywords: Animal model; Compressive loading; Muscle damage; Pressure ulcers