System and method for preventing intraoperative fracture in cementless hip arthroplasty

1. A method for monitoring impaction of a femoral component of a hip prosthesis into a femur, comprising:

receiving impaction data generated during the impaction of the femoral component into the femur from at least one accelerometer attached to the femoral component;

normalizing the impaction data into a usable format as normalized impaction data;

calculating a total norm of an acceleration signal including the normalized impaction data based on the following equation:

Norm

Total

=

∑

i

=

1

N

⁢

a

i

2

 where N is a number of points in a time interval to be analyzed and a is an acceleration measurement taken at an i th point by the accelerometer;

calculating an impaction monitoring metric E j for a femoral component impaction hit as a fraction of the total norm of the acceleration signal during the time interval at a j th point based on the following equation:

E

j

=

∑

i

=

1

j

⁢

a

i

2

Norm

Total

determining a time t(j) corresponding to a fractional value E j within a predetermined range indicative of the femoral component being fully seated for each of a plurality of femoral component impaction hits that is equal to a length of time required for E j to reach a predetermined fractional value indicative of femoral component fit and stability after the impaction hit; and

generating an output based on the time t(j) for the femoral component impaction hit, the output being indicative of the femoral component fit and stability.

2. The method of claim 1 , wherein the length of time t(j) required for E j to reach a predetermined fractional value indicative of femoral component fit and stability after the impaction hit corresponds to E j =0.99.

3. The method of claim 1 , wherein the receiving of impaction data comprises receiving output acceleration data generated during the impaction of the femoral component into the femur from a single accelerometer attached to the femoral component.

4. The method of claim 3 , wherein the single accelerometer is oriented in an impaction direction of the femoral component along a relative z axis.

5. The method of claim 1 , wherein the generating an output based on the time t(j) for the femoral component impaction hit comprises generating an output based on the time t(j) corresponding to E j =0.99 for the femoral component impaction hit.

6. A system for monitoring femoral component fit and stability during impaction of a femoral component of a hip prosthesis into a femur, comprising:

a testing component including at least one accelerometer that is attachable to the femoral component, the at least one accelerometer being operable to generate impaction data corresponding to the impaction of the femoral component into the femur;

a data acquisition and analysis device in communication with the at least one accelerometer and configured to receive the impaction data, normalize the impaction data into a usable format as normalized impaction data and calculate an impaction monitoring metric by calculating

(1) a total norm of an acceleration signal including the normalized impaction data as

Norm

Total

=

∑

i

=

1

N

⁢

a

i

2

 where N is a number of points in a time interval to be analyzed and a is an acceleration measurement taken at an i th point by the accelerometer,

(2) a fraction of the total norm of the acceleration signal during the time interval at j th point as

E

j

=

∑

i

=

1

j

⁢

a

i

2

Norm

Total

 and

(3) a time t(j) that is equal to a length of time required for E j to reach a predetermined fractional value indicative of femoral component fit and stability after each of a plurality of femoral component impaction hits; and

a user interface in communication with the data acquisition and analysis device and configured to provide feedback indicative of femoral component fit and stability data based on the impaction monitoring metric.

7. The system of claim 6 , wherein the length of time required for E j to reach a predetermined fractional value indicative of femoral component fit and stability is E j =0.99.

8. The system of claim 6 , wherein the at least one accelerometer comprises an output accelerometer for generating an output acceleration signal including the impaction data generated by impaction of the femoral component.

9. The system of claim 6 , wherein the at least one accelerometer comprises a single accelerometer attached to the femoral component and oriented in an impaction direction of the femoral component along a relative z axis.

10. A system for monitoring femoral component fit and stability during impaction of a femoral component of a hip prosthesis into a femur, comprising:

a testing component including at least one measurement transducer that is attachable to the femoral component, the at least one measurement transducer being operable to generate impaction data corresponding to the impaction of the femoral component into the femur;

a data acquisition and analysis device in communication with the at least one measurement transducer and configured to receive the impaction data, normalize the impaction data into a usable format as normalized impaction data, calculate an impaction monitoring metric, and calculate a time t (j) required for the impaction monitoring metric to reach a predetermined value that is indicative of a femoral component fit and stability for each impaction hit; and

a user interface in communication with the data acquisition and analysis device and configured to provide feedback based on the value of t (j) for each impaction hit;

wherein the data acquisition and analysis device is configured to calculate the impaction monitoring metric based on the normalized impaction data by processing measurement transducer signals including the impaction data to produce an impaction monitoring metric based on at least one of signal frequency, signal time history, signal stationarity, signal interrelation, neural network calculations and/or energy dissipation.

11. A computer readable medium comprising instructions that are executable by a computer, the instructions including a computer implemented method for monitoring impaction of a femoral component of a hip prosthesis into a femur, the instructions for implementing the steps of:

receiving impaction data generated during the impaction of the femoral component into the femur from at least one transducer attached to the femoral component; and

normalizing the impaction data into a usable format as normalized impaction data by calculating a total norm of an acceleration signal including the impaction data as

Norm

Total

=

∑

i

=

1

N

⁢

a

i

2

 where N is a number of points in a time interval to be analyzed and a is an acceleration measurement taken at an i th point by the accelerometer; and

calculating a fraction of the total norm of the impaction signal during the time interval at a j th point as an impaction monitoring metric based on the following formula:

E

j

=

∑

i

=

1

j

⁢

a

i

2

Norm

Total

 and;

where a time, t(j), corresponding to a fractional value E j within a predetermined range indicative of the femoral component being fully seated is determined for calculating a time t(j) that is equal to a length of time required for E j to reach a predetermined fractional value indicative of femoral component fit and stability after each of a plurality of femoral component impaction hits.

12. The computer readable medium of claim 11 , wherein the length of time required for E j to reach a predetermined fractional value indicative of femoral component fit and stability is 0.99.

13. The computer readable medium of claim 11 , wherein the instructions are further for implementing the step of:

generating an output based on the time t(j) for each of the femoral component impaction hits, the output being indicative of femoral component fit and stability.