Abstract: To address technical problems facing knee arthroplasty resection validation, the present subject matter provides a tracked knee arthroplasty instrument for objective measurement of resection depth. By performing a precise comparison between the location of the tracked knee arthroplasty instrument and a reference location, the knee arthroplasty instrument measures and validates each tibial and femoral resection. To address technical problems facing validation of joint laxity following knee arthroplasty, the tracked knee arthroplasty instrument is shaped to validate the flexion gap and extension gap. When the tracked knee arthroplasty instrument is inserted between the resected tibial plateau and femoral head, the instrument shape validates whether the desired flexion gap and extension gap have been achieved.