Tension meter for orthopedic surgery

• US 5,213,112 A
• Filed: 01/29/1992
• Issued: 05/25/1993
• Est. Priority Date: 01/29/1992
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Pfizer Hospital Products Group, Inc. (Pfizer Inc.)
• Inventors: Sakakibara, Mineo, Niwa, Shigeo
• Primary Examiner(s): Hindenburg, Max
• Assistant Examiner(s): Tucker, Guy V.
• Application Number:
  US07/827,308
• Time in Patent Office: 482 Days
• Field of Search: 128/774, 128/782, 128/781, 606/53, 606/57, 606/58, 606/61, 606/60, 606/90, 606/99, 606/102, 606/105, 606/88, 73/862.23, 73/862.21, 73/862.42
• US Class Current: 600/587
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 2017/0268 for the knee
• CPC Class Codes: A61B 2090/031 torque limiting
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61B 90/06 Measuring instruments not otherwise provided for
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension

Abstract

A tension meter for measuring the degree of tension between bones has a grip portion, a tension meter body mounted to the grip portion, and a torque setting device rotatably connected through a torque shaft to the tension meter body. The tension meter body includes a body portion, a fixed arm extending from one end of the body portion, and a movable arm mounted on the body portion so as to be movable away therefrom. The movable arm is located in opposed relationship to the fixed arm. The movable arm is provided with a gear portion meshing the torque shaft. The torque setting device is provided with a torque limiter for limiting relative displacement of the movable arm in relation to the fixed arm according to a force to be applied between the fixed arm and the movable arm. Use of the tension meter produces quantitative data which makes it possible to carry out surgical operations with reproducible results because they do not rely only upon the surgeon'"'"'s senses.

Claims

1. A tension meter for orthopedic surgery for expanding openings between bones and measuring a degree of tension between said bones before implanting a prosthetic device bone between the bones, the tension meter comprising:

a grip portion, a tension meter body mounted to said grip portion, a torque shaft operatively coupled to said body, said torque shaft having gear teeth formed therein, and a torque setting device rotatably connected through said torque shaft to said tension meter body, said torque setting device including means for measuring torque and limiting the torque to a predetermined value;

said tension meter body comprising a body portion, a fixed arm extending from one end of said body portion and a movable arm mounted on an upper surface of said body portion so as to be movable away therefrom, said movable arm being located above said fixed arm in opposed relationship thereto, said movable arm being provided with a gear portion for meshing with the gear teeth on said torque shaft;

said torque setting device including a means on said torque shaft for limiting torque by limiting relative displacement of said movable arm away from said fixed arm and therefore the force applied to the bone between said fixed arm and said movable arm is limited by said predetermined torque value.

2. The tension meter as set forth in claim 1 wherein said gear portion on said movable arm is in the form of a rack and said gear teeth on said torque shaft are in the form of a pinion.

3. The tension meter as set forth in claim 1 wherein, a second removable arm is mounted on said upper surface of said body portion.

4. The tension meter as set forth in claim 1 wherein said torque setting device includes means for measuring and displaying the torque generated by the force applied between said fixed arm and said movable arm.

5. A tensioning device for setting the tension of ligaments extending between two bones during orthopedic surgery comprising:

a body portion having a first arm extending therefrom for engaging the first of the bones and a second arm for engaging the second of the bones moveable with respect to said first arm and extending generally parallel thereto, said second arm having a drive portion extending through said body, said drive portion having gear teeth formed thereon;

a torque shaft extending through said body, said torque shaft having gear teeth formed thereon in meshing engagement with said gear teeth on said drive portion; and

means for pre-setting the tension of the ligaments including means mounted on said torque shaft for pre-setting the torque generated thereon, said means for pre-setting further including a means for limiting the movement of said first and second arms away from one another against the tension in the ligaments to a predetermined distance.

6. The tension meter as set forth in claim 5 wherein said drive portion on said movable arm is in the form of a rack and said gear teeth on said torque shaft are in the form of a pinion.

7. The tension meter as set forth in claim 5 wherein said second arm comprises a pair of arms mounted on said body portion.

8. The tension meter as set forth in claim 5 wherein said torque setting device includes means for measuring and displaying the torque generated by the force applied between said fixed arm and said movable arm.