Device for Inserting a Surgical Pin

Damaged and diseased joints which are no longer functional can be replaced by prosthetic joints, such as a knee joint during an arthroplasty. In order to prepare an area of a joint to receive a prosthetic joint component, angled cuts are made in a bone to resection it. The cuts must be accurate in order for the prosthetic joint components to be properly secured to the bone and for the joint to function without discomfort to the recipient and abnormal wear of the joint.

Various orthopaedic instruments, such as cutting guides, are often used to obtain accurate cuts in a bone. Typically, such a guide is secured to an end of a bone, such as a tibia, with surgical pins prior to resection. In many instances force must be applied to the surgical pins, typically with a surgical mallet, to insert the pins into bone. This task becomes complicated when a pin must be inserted at an awkward angle or where space constraints provide only limited access to the pin. Such complications increase the risk of inaccurate insertion of the pin and could compromise success of the surgery.

Another obstacle to effective pin insertion is that the pins, which are normally positioned and held in place during hammering, can become coated with bodily fluids and thus become quite slippery during a surgical procedure. This condition can cause pin handling and manipulation to become quite difficult. Furthermore, retractable pins associated with a cutting instrument, for example, may be difficult to access directly with a mallet. It will be appreciated that the above problems impart inefficiencies and extra time to a surgical procedure thereby increasing the risk to a patient.

The present invention provides a device useful to manipulate and insert surgical pins, such as Steinman pins. The pin insertion device has a mechanism for releasably retaining an end of the pin, and it also provides a means of imparting an accurate impact force to the pin.

The device for inserting a surgical pin includes a body portion having a first end defining a bore and a retainer disposed within the bore for releasably engaging a portion of the pin. The bore includes a surgical pin insertion limitation surface for limiting the depth to which the pin can be inserted into the device and a wall portion extending from the surgical pin insertion limitation surface to a first aperture which defines an entry into the bore. A recess within the wall portion is located at a point between the surgical pin insertion limitation surface and the first aperture. The retainer for releasably engaging a portion of the pin is at least partially disposed within the recess.

In one embodiment, the retainer is an elastically deformable O-ring which has an inner diameter less than a diameter of the pin. Upon insertion of the pin into the bore, portions of the O-ring in contact with the pin deform and frictionally engage the pin.

In a further feature of the invention, the body includes a second end defining an impact surface for receiving an impact. The force of the impact on the impact surface is transferred to a surgical pin engaged by the device at the pin insertion limitation surface. The impact surface enhances the ability of a surgeon to accurately apply a force to the surgical pin to insert the pin in a bone. An ergonomically contoured handle region can be provided intermediate the first and second ends of the device.

The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a surgical pin insertion device in accordance with the present invention;

FIG. 2 is a cross sectional view of the surgical pin insertion device of FIG. 1;

FIGS. 3A-3B are cross sectional views of alternative embodiments of the surgical insertion device of FIG. 1;

FIGS. 4A-4B are cross sectional views of further embodiments of the surgical pin insertion device of FIG. 1;

FIG. 5 is a perspective view of the surgical pin insertion device of FIG. 1 shown in conjunction with a conventional tibial cutting block orthopaedic instrument; and

FIG. 6 is a perspective view of the surgical pin insertion device of FIG. 1 shown in conjunction with a conventional femoral locating orthopaedic instrument.

Referring now to FIGS. 1 and 2, a surgical pin insertion device 10 includes a body portion 12 having a first end 14 defining a bore 16. The bore 16 includes a surgical pin insertion limitation surface 18 and a wall portion 20 extending from the surgical pin limitation surface to a first aperture 22 which defines an entry into the bore 16. A recess 24 within the wall portion 20 is located between the pin insertion limitation surface 18 and the first aperture 22. A retainer 26 is disposed within the recess 24 for releasably engaging a portion of a surgical pin 27.

In the exemplary embodiment of FIG. 2, the retainer 26 is an elastically deformable O-ring disposed within the recess 24. The O-ring 26 defines an inner diameter less than a diameter of the surgical pin 27 at a portion of the pin insertable within the bore 16. The O-ring is formed from rubber in an illustrative embodiment, but other conventional elastomeric materials can also be used. In another embodiment shown in FIG. 3A, the retainer 26' comprises at least one biased retaining member or spring. In a further embodiment shown in FIG. 3B, the retainer 26" includes a magnetic element for engaging a pin.

The device 10 includes an optional second aperture 28 extending through the wall portion 20 into the bore 16 for providing a visual indication that the pin 27 is engaged in the bore. In other embodiments, the device includes further apertures having other shapes and sizes than that described herein.

In an exemplary embodiment, the device 10 has a frusto-conical lip 30 which defines the first aperture 22 and guides an end of the pin 27 into the bore 16. A first section 32 of the wall portion adjacent the first aperture 22 defines a first diameter greater than a second diameter defined by a second section 34 of the wall portion. The larger diameter of the first section 32 enhances the ease of insertion of a pin 27 into the bore 16 while the smaller diameter of the second section 34 approximates a diameter of the pin 27 so that an elongate portion of the pin protruding from the bore rigidly extends from the device for precise positioning of the pin 27. As shown in the exemplary embodiment, the wall portion 20 of the bore 16 is smooth and cylindrical to accommodate a cylindrical surgical pin. In other embodiments, the wall portion is fluted or otherwise textured, while still maintaining the pin and bore in substantially concentric relation. Furthermore, the bore is not limited to a cylindrical shape, as other embodiments include a square or triangular bore.

In a further feature of the invention, the body 12 has a contoured external surface 36 for allowing a user to comfortably handle and precisely manipulate the device in a surgical environment. It will be appreciated by one skilled in the art that the dangerously sharp surgical pins often become wet and slippery during a surgical procedure and therefore are difficult to handle. Also, the pins are small as compared with the device and thus are less easily perceived by a user. The contoured body provides a way to efficiently and accurately position a pin. The contour of the device is not to be limited to that disclosed herein.

In an illustrative embodiment, the device 10 includes a second end 38 mushrooming into a flat, or slightly rounded, impact surface 40 for providing an increased surface area which can be struck with a surgical mallet, for example. The impact surface 40 is easily seen by a surgeon as compared with an end of a surgical pin. In addition, the significant surface area of the impact surface 40 reduces or eliminates occurrences of a surgeon missing the target and inadvertently striking an instrument or patient with the mallet.

An exemplary surgical pin 27 is a Steinman pin having a standard 0.125 inch diameter. The pin 27 includes an elongate portion 42 terminating in a sharpened insertion end 44 and a head portion 46. In an illustrative embodiment, the head portion 46 includes a plurality of beveled surfaces 48 which define a triangular cross section allowing the pin to be easily inserted into the bore 16.

In the exemplary embodiment of FIG. 2, the pin insertion limitation surface 18 is a continuous surface terminating the bore 16. In another embodiment shown in FIG. 4A, a bore 16' progressively narrows to a point wherein a cross sectional area of the bore is less than that of the pin, thereby forming a pin insertion limitation surface 18'. In a further embodiment shown in FIG. 4B, a bore 16" continues beyond the pin insertion limitation surface 18" which is defined by a member 19 disposed across the bore. Other embodiments known to one of ordinary skill in the art to limit insertion of a pin are possible and within the scope of the present invention.

In operation, the head portion 46 of the pin 27 is inserted into the bore 16 until the head portion contacts the pin insertion limitation surface 18. The O-ring 26 is compressed at portions which contact the pin 27 thereby frictionally engaging the pin.

In an exemplary embodiment, upon reaching the maximum insertion depth, the O-ring 26 contacts a portion of the cylindrical, elongate portion 42 of the pin just beyond the triangular head portion 46 of the pin. This minimizes the force required to insert the pin 27 up to complete insertion and maximizes the force required to remove the pin by increasing the contact surface area, and therefore the friction, between the O-ring 26 and the pin at the point of complete insertion. Other embodiments of the device include differing bore depths and geometries adapted for pins of other shapes and sizes.

In an exemplary embodiment, a pin 27 engaged in the bore 16 is retained in any spatial orientation of the device and in the presence of movement of the device and significant inertial forces. The pin 27 is removed from the device with relative ease by applying a force aligned with a longitudinal axis of the pin, for example by pulling the device away from the pin after the pin has been inserted in a bone. It will be appreciated that the amount of force required to remove the pin from the device can be varied considerably depending upon the desired application. Selection of an O-ring inner diameter, coefficient of friction, and elasticity establish a predetermined disengagement force.

The surgical pin insertion device of the present invention is well suited for securing orthopaedic instruments to a bone of a patient. FIG. 5 shows the device 10 for inserting a surgical pin used in conjunction with a tibial cutting block 100. As will be appreciated by one of ordinary skill in the art, the cutting block 100 must be positioned and accurately secured to the bone in order to properly resect a tibia of a patient. To secure the cutting block 100, a series of surgical pins 27 are individually engaged by the device 10 and inserted into a bone through selected apertures 45 in the cutting block. The pin insertion device 10 releasably engages the head portion 46 of the surgical pin wherein the insertion end 44 of the pin is placed in a desired aperture 45. The impact surface 40 is hammered with a surgical mallet to insert the pin 27 to a desired depth. Thus, the device 10 provides a way for a surgeon to quickly and accurately secure the cutting block with the surgical pins.

FIG. 6 shows the device 10 for inserting a surgical pin used in conjunction with a femoral locating device 200 which is secured with retractable pins 27'. Retractable pins 27' associated with an instrument are often difficult to access directly with a mallet or other impact means. The first end 14 of the device can be placed in contact with an end of the retractable pin 27' and the impact surface 40 of the device can be struck to insert the retractable pin into a bone of patient.

One skilled in that art will realize further features and advantages of the invention from the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.