# US 11,298,246 B1 · Apparatus and method for evaluating knee geometry

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- Number: US 11,298,246 B1
- Document ID: US11298246B1
- Status: Granted
- Kind: B1
- Application number: 17/145,326
- Filed: 2021-01-09
- Granted: 2022-04-12
- Earliest claimed: 2020-05-19
- Assignees: Little Engine, LLC
- Applicants: Little Engine, LLC
- Inventors: J. Dean Cole; Franz W. Kellar; Michael D. Bissette; Franz Austen Kellar; Harold L. Crowder
- Web page: https://patentgrep.com/patent/US11298246B1

## CPC

- A61F 2/4657: {Measuring instruments used for implanting artificial joints (for surgical instruments A61B90/06)}
- A61B 5/1036: {Measuring load distribution, e.g. podologic studies}
- A61B 5/4533: {Ligaments}
- A61B 5/4585: {Evaluating the knee}
- A61B 5/686: {Permanently implanted devices, e.g. pacemakers, other stimulators, biochips (A61B5/6861 takes precedence)}
- A61B 17/025: {Joint distractors}
- A61B 34/10: Computer-aided planning, simulation or modelling of surgical operations
- A61B 34/20: Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
- A61F 2/461: {of knees}
- G01L 5/16: for measuring several components of force
- G16H 10/60: for patient-specific data, e.g. for electronic patient records
- G16H 20/40: relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture
- G16H 40/20: for the management or administration of healthcare resources or facilities, e.g. managing hospital staff or surgery rooms
- G16H 40/67: for remote operation
- G16H 50/20: for computer-aided diagnosis, e.g. based on medical expert systems
- A61B 5/6847: {mounted on an invasive device}
- A61B 17/14: Surgical saws ({A61B17/1637 takes precedence;} dental saws for teeth A61C3/12)
- A61B 17/1622: {Drill handpieces (A61B17/1626, A61B17/1628 take precedence)}
- A61B 2017/00398: {using powered actuators, e.g. stepper motors, solenoids}
- A61B 2017/00557: {inflatable (A61B2017/22051 takes precedence)}
- A61B 2017/0268: {for the knee}
- A61B 2034/105: {Modelling of the patient, e.g. for ligaments or bones}
- A61B 2034/2055: {Optical tracking systems}
- A61B 2034/256: {having a database of accessory information, e.g. including context sensitive help or scientific articles}
- A61B 2090/064: {for measuring force, pressure or mechanical tension}
- A61B 2090/065: {for measuring contact or contact pressure}
- A61B 2090/3983: {Reference marker arrangements for use with image guided surgery}
- A61B 2090/502: {Headgear, e.g. helmet, spectacles}
- A61F 2002/3895: {unicompartimental}
- A61F 2002/4633: {for selection of endoprosthetic joints or for pre-operative planning}
- A61F 2002/4666: {for measuring force, pressure or mechanical tension}
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA

## Abstract

A method of evaluating a human knee joint which includes a femur bone, a tibia bone, a patella bone, a patellar tendon, and ligaments, wherein the ligaments and patellar tendon are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method including: inserting into the knee joint a gap balancer that includes a tibial interface surface, an opposed femoral interface surface, and at least one force sensor, the method including: providing an electronic receiving device; moving the knee joint through at least a portion of its range of motion; while moving the knee joint, using the electronic receiving device to collect data from the at least one force sensor; processing the collected data to produce a digital geometric model of at least a portion of the knee joint; and storing the digital geometric model for further use.

## Claims

### Claim 1

A method of evaluating a human knee joint which includes a femur bone, a tibia bone, a patella bone, and ligaments, wherein the ligaments are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method comprising:
inserting into the knee joint a gap balancer that includes a tibial interface surface, an opposed femoral interface surface, an array of tibial force sensors disposed on the tibial interface surface, and an array of femoral force sensors disposed on the femoral interface surface;
providing an electronic receiving device;
moving the knee joint through at least a portion of its range of motion;
while moving the knee joint, using the electronic receiving device to collect data from the at least one force sensor, wherein the data includes information from the array of tibial force sensors and the array of femoral force sensors;
processing the collected data to produce a digital geometric model of at least a portion of the knee joint; and
storing the digital geometric model for further use.

### Claim 2 (depends on 1)

The method of claim 1 wherein each of the arrays of force sensors has at least a two-axis array resolution.

### Claim 3 (depends on 2)

The method of claim 2 wherein each of the two-axis arrays lies on a non-planar surface.

### Claim 4 (depends on 1)

The method of claim 1 wherein the gap balancer includes one or more individual devices, each of the one or more individual devices placed within a single compartment of the knee joint.

### Claim 5 (depends on 1)

The method of claim 1 further comprising:
computing one or more tool paths passing through the knee joint;
coupling at least one tracking marker to the knee joint;
receiving data representing an actual position and orientation of a tool relative to the at least one tracking marker;
moving a tool along the one or more tool paths, with reference to the data, so as to remove bone from the knee joint, thereby forming a machined feature in the knee joint.

### Claim 6 (depends on 1)

The method of claim 1 further including using a force sensor to collect data from the interface surface between the patella and the femur.

### Claim 7 (depends on 6)

The method of claim 6 wherein the force sensor also produces position or displacement data.

### Claim 8 (depends on 7)

The method of claim 7 further comprising force and displacement data being shown graphically to a user.

### Claim 9 (depends on 1)

The method of claim 1 further comprising:
connecting at least one position tracking sensor directly or indirectly to the knee joint;
collecting position data from the position tracking sensor while moving the knee joint; and,
using the position data and the force data to produce the geometric model.

### Claim 10 (depends on 1)

The method of claim 1 wherein the patella remains in its native anatomical position during all steps of the method.

### Claim 11 (depends on 1)

The method of claim 1 further comprising using the gap balancer to distract the knee joint.

### Claim 12 (depends on 11)

The method of claim 11 wherein the distraction is carried out by:
inserting the gap balancer between the tibia and the femur, with the gap balancer in a retracted position; and
moving the gap balancer towards an extended position, so as to urge the tibia and the femur apart and apply tension to ligaments of the knee joint.

### Claim 13 (depends on 1)

The method of claim 1 wherein the data is compiled in a database and learning system.