Mobile monitoring of fracture healing in external fixators

Abstract

A device for and a method of monitoring the healing status of a fractured bone in a person's limb is disclosed. The external fixation device may include one or more rods or struts that incorporate strain gauges designed to measure the mechanical forces on the strut when force is applied to the fractured bone. The mechanical force data may be collected by an electronic module and transmitted to a computer for statistical analysis. The device may also include a foot insole sensor for measuring the foot plantar force to normalize the data collected by an external fixation device attached to a person's leg. The method of measuring the healing status of a fractured bone includes measuring the changes in mechanical forces exerted on the one or more struts, and based on the measurements, estimating the healing status of the bone.

What is claimed is: 
     
         1 . A method of measuring the healing status of a fractured bone, the method comprising:
 modifying an external fixator apparatus that is attached to a patients limb to include one or more struts comprising one or more gauges configured to measure the strains acting on the strut;   exerting varying amount of pressure on the patient's limb;   measuring data covering the changes in strains acting on the strut as the patient exerts varying amounts of pressure on the strut; and   normalizing the data by including a measured foot plantar force.   
     
     
         2 . The method of  claim 1 , wherein the patient's limb is a leg;
 measuring the foot plantar force as the patient walks on said leg.   
     
     
         3 . The method of  claim 2 , further comprising normalizing the measured changes in mechanical forces acting on the strut as the patient walks based on the foot plantar force that is measured. 
     
     
         4 . The method of  claim 1 , further comprising calculating the mechanical forces acting on the strut and estimating the healing status of a bone fracture based on the mechanical forces. 
     
     
         5 . The method of  claim 1 , further comprising transmitting the measured changes in strains as data to a computer. 
     
     
         6 . The method of  claim 5 , wherein the transmitting step is wireless. 
     
     
         7 . The method of  claim 6 , wherein the wireless transmission is Bluetooth. 
     
     
         8 . The method of  claim 1 , wherein the foot plantar force is measure using portable instrumented shoe insoles. 
     
     
         9 . The method of  claim 8 , further comprising calibrating the portable instrumented shoe insoles using a patient's body weight. 
     
     
         10 . A system for measuring the healing status of injured limb, comprising:
 an external fixator comprising a frame including one or more ring members, a plurality of strut members interconnecting the one or more ring members, and wherein at least one of the plurality of strut members comprises one or more strut gauges configured to measure the strains acting on the at least one of the plurality of strut members; and   a secondary sensor remote of the external fixator to acquire secondary data associated with the force applied by the injured limb;   wherein the secondary data is used to normalize the measured data of the external fixator.   
     
     
         11 . The system of  claim 10 , wherein the secondary sensor comprises a portable instrumented shoe insole. 
     
     
         12 . The system of  claim 11 , wherein the secondary data comprises measured foot plantar forces. 
     
     
         13 . The system of  claim 12 , wherein the portable instrumented shoe insole is calibrated using a weight of a patient having the injured limb. 
     
     
         14 . The system of  claim 11 , further comprising a wireless transmitter for wirelessly transmitting the secondary data, wherein the wireless transmitter is attached to a shoe with the portable instrumented shoe insole. 
     
     
         15 . The system of  claim 14 , wherein the external fixator further comprises a wireless module to transmit measured strain to a computer. 
     
     
         16 . The system of  claim 15 , wherein the computer collects and stores the measured strain data and the secondary data. 
     
     
         17 . A method of measuring the healing status of an injured limb, comprising:
 measuring strain acting on an external fixator connected to the injured limb, the external fixator comprising a frame including one or more ring members, a plurality of strut members interconnecting the one or more ring members, and wherein at least one of the plurality of strut members comprises one or more strut gauges;   measuring secondary data remote of the external fixator with a secondary sensor measuring applied force by the injured limb; and   normalizing the measured strain by the external fixator using, in part, the secondary data acquired by the secondary sensor.   
     
     
         18 . The method of  claim 17 , further comprising transmitting measured strain and the secondary data to a computer, wherein the computer normalizes the measures strain. 
     
     
         19 . The method of  claim 18 , further comprising comparing, at the computer, the normalized strain with a previously stored normalized strain to determine the healing status of the injured limb. 
     
     
         20 . The method of  claim 18 , wherein the step of transmitting the measured strain and the secondary data is done in a wired or wireless manner.