Apparatus and method for monitoring bone-fracture union

Claim 1

A non-invasive bone-fracture union-monitoring system comprising a preformed fracture cast sleeve for fitting to a patient's limb containing a bone fracture the union of which is to be monitored, an elastomeric transducer adherent to the external surface of said sleeve at a predetermined location thereon, said transducer being electrically conductive and having an electrical resistance which varies with elastic extension and contraction of the transducer, means for establishing a measure of the mass of the limb containing the bone-fracture, a resistance sensitive electrical network connected to the transducer to measure variations in the electrical resistance of the transducer when a force is applied to the limb to effect lateral bone movement at the fracture site, and data evaluating means connected to said network and arranged to evaluate the extent of said bone movement at measured time intervals during progressive union of the bone and consequentially to predict the time lapse until substantially zero bone movement at the fracture site when bone union is completed.

Claim 13

A method of non-invasively monitoring bone union at a bone-fracture in a patient's limb, said method comprising providing a preformed fracture cast sleeve having an elastomeric transducer adherent at a predetermined location on the external surface of said sleeve the transducer being electrically conductive and having an electrical resistance which varies with elastic extension and contraction thereof, fitting said sleeve to said limb with said transducer adjacent the bone-fracture site, intermittently within the anticipated time scale of the fracture union connecting the transducer to a resistance sensitive network, imposing a force on the bone fracture site during each such connection and measuring the amplitude and duration of the electrical resistance-change signal output by the transducer as monitored by the resistance-sensitive network and indicative of limited lateral bone movement at said site, storing a plurality of such measurement readings together with the dates on which said readings were recorded and a measure of the mass of the limb containing the fracture site, and analyzing the stored readings on a time scale determined by the date data by curve-fitting with a curve predetermined by said mass measure to identify a trend in the readings and thereby predict the time lapse until substantially zero bone movement at the bond-fracture site when bone union is completed.

Claim 14

A method of non-invasively monitoring bone union at a bone-fracture in a patient's limb, said method comprising providing a preformed fracture cast sleeve having an elastomeric transducer adherent at a predetermined location on the external surface of said sleeve the transducer being electrically conductive and having an electrical resistance which varies with elastic extension and contraction thereof, fitting said sleeve to said limb with said transducer adjacent the bone-fracture site, intermittently within the anticipated time scale of the fracture union connecting the transducer to a resistance sensitive network, imposing a force on the bone fracture site during each such connection and measuring the amplitude and duration of the electrical resistance-change signal output by the transducer as monitored by the resistance-sensitive network and indicative of limited lateral bone movement at said site, storing a plurality of such measurement readings together with the dates on which said readings were recorded and a measure of the mass of the limb containing the fracture site, and analyzing the stored readings on a time scale determined by the date data by curve-fitting with a curve predetermined by said mass measure to identify a trend in the readings and thereby predict the time lapse until substantially zero bone movement at the bond-fracture site when bone union is completed.