Skull clamp with load distribution indicators

• US 20040097985A1
• Filed: 10/17/2003
• Published: 05/20/2004
• Est. Priority Date: 04/17/2001
• Status: Active Grant

• Current Assignee: Integra Lifesciences Corporation (Integra LifeSciences Holdings Corporation)
• Original Assignee: Ohio Medical Instrument Co., Inc.
• Inventors: Lincoln, Donald A., Day, James L.
• Granted Patent: US 7,229,451 B2
• Time in Patent Office: Days
• US Class Current: 606/151
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: A61B 90/14 Fixators for body parts, e.g. skull clamps; Constructional details of fixators, e.g. pins

Abstract

A three-pin skull clamp [10] includes a C-shaped frame [12] which partially encircles the head [15] of the patient, with a spring-loaded single skull pin assembly [22] located at one end of the frame [12] and adapted to engage the head [15] of the patient with a desired engagement force, and two spaced skull pins [30] mounted to a rocker arm [44] located at an opposite end of the frame [12]. Each of the rocker arm skull pins [30] resides in operative contact with an indicator cap [66] held by a spring-loaded pin carrier assembly [50], the indicator cap [66] being movable relative to the rest of the pin carrier assembly [50] in response to the engagement force applied to the corresponding skull pin [30] by the head [15] of the patient. By visibly comparing the positions of the indicator caps [66] relative to their respective pin carrier assemblies [50], one can readily determine whether the engagement forces are equally distributed between the two rocker arm skull pins [30]. If the indicator caps [66] show significantly unequal load distribution, the rocker arm [44] can be pivotally adjusted to produce a rocker arm orientation which results in a more equal load distribution on the two spaced rocker arm skull pins [30].

Claims

1. A skull clamp for holding the head of a patient comprising:

a C-shaped frame have first and second legs adapted to reside on opposite sides of the head;

a single side skull pin and a single pin assembly held by the first leg, on a first side of the head;

a rocker arm assembly held by the second leg, on a second side of the head, the rocker arm assembly supporting a pair of rocker arm skull pins in spaced relation; and

a pair of skull pin carrier assemblies held to the rocker arm assembly in spaced relation, each supporting a rocker arm skull pin, the single side skull pin and said pair of rocker arm skull pins adapted to securely hold the head of the patient, each skull pin carrier assembly further including an indicator cap operatively contacting the respective rocker arm skull pin, each indicator cap being movable relative to the rest of the carrier assembly in response to head engagement force applied to the corresponding rocker arm skull pin, thereby to provide a comparative indication of load distribution to said pair of rocker arm skull pins.

2. The skull clamp of claim 1 wherein each skull pin carrier assembly further comprises:

a hollow adjustment screw removably received within one end of the rocker arm assembly; and

the indicator cap movable relative to the adjustment screw to provide a visible indication of the engagement force applied to the respective skull pin by the head of the patient.

3. The shill clamp of claim 2 where each pin carrier assembly further comprises:

a piston residing within the hollow adjustment screw, the piston having at a first end thereof an enlarged head residing in contact with the respective rocker arm skull pin, the indicator cap held to a second opposite end of the piston.

4. The skull clamp of claim 3 wherein each of the pin carrier assemblies further comprises:

a spring operatively associated with the adjustment screw and the piston, the spring biased so as to hold the indicator cap in a desired position relative to the outer end of the pin carrier assembly.

5. The skull clamp of claim 4 wherein each spring holds the respective indicator cap within a recess.

6. The skull clamp of claim 1 wherein each of the pin carrier assemblies resides within a correspondingly shaped bore formed in an end of the rocker arm assembly.

7. The skull clamp of claim 6 wherein each pin carrier assembly is threadably received within the corresponding complementarily threaded bore in the rocker arm assembly, thereby to permit adjustment of the relative positions of the pin carrier assemblies and their corresponding skull pins relative to the rocker arm assembly.

8. A skull clamp for rigidly holding the skull of the patient during surgery comprising:

a C-shaped frame to partially encircle the head of the patient, the frame having first and second ends adapted to be located on opposite sides of the skull of the patient;

a threaded pin assembly located at a first end of the frame, said assembly including a single skull pin and being adjustable relative to the first end of the frame to enable an operator to selectively determine the force applied to the skull of the patient by the corresponding single skull pin; and

a pair of spaced skull pins adapted to engage and hold the skull of the patient opposite the single skull pin, said pair of spaced skull pins located at a second end of the frame, each of said pair of spaced skull pins operatively contacting an indicator, each of the indicators being movable relative to the second end of the frame in response to the engagement force applied by the skull of the patient to the respective skull pin, thereby to provide an indication of the load distribution of the engagement forces on said pair of spaced skull pins.

9. The skull clamp of claim 8 wherein said pair of skull pins are mounted in spaced relation on a rocker arm located at the second end of the frame, the first and second ends of the frame aligned along an axis which bisects the skull of the patient, the rocker arm being rotatable relative to the axis to facilitate placement of said pair of skull pins in desired positions relative to the skull of the patient.

10. The skull clamp of claim 9 wherein each of said pair of skull pins resides within a bore located at an end of the rocker arm, and further comprising:

a pair of pin carrier assemblies, each pin carrier assembly held within the bore and holding the respective indicator in operative contact with the respective skull pin.

11. The skull clamp of claim 10 wherein each of the two pin carrier assemblies further comprises:

a spring biasing, the respective indicator in a desired position relative to the frame, so that the indicator moves relative to the frame in response to force on the skull pin only after the force of the spring is overcome.

12. The skull clamp of claim 11 wherein each indicator includes markings to facilitate visual detection of the movement of the indicator relative to the frame, thereby to facilitate comparison of the load distribution between said pair of spaced skull pins.