Patent Application
20050059978
The present invention relates to surgical apparatus and surgical methods and in particular those associated with osteotomological surgery on either humans or animals.
The invention has been developed primarily for use in hip replacement surgery and will be described hereinafter with reference to this application. However, it will be appreciated that the apparatus of the present invention is not limited to this particular field of use, but rather may be adapted for use with any bone structure and in relation to various types of surgery.
Prior art hip replacement surgical techniques typically involve a surgeon firstly making a fairly large initial incision so as to reveal the hip joint. The surgeon then typically manipulates the leg of the patient to dislocate the hip bone. This often requires the application of significant force to effect dislocation. Excessive manipulation and application of force may cause collateral damage to the patient, possibly resulting in post operative pain and/or an extended healing time. The head of the femur is then cut off at the neck. A cavity is reamed into the hip to accept a prosthetic acetabular cup (for example a LINK T.O.P. Acetabular Cup) and a prosthetic stem (for example a LINK C.F.P. Hip Stem) is inserted into the femoral shaft. Typically the surgeon aligns the cutting and reaming tools by eye, possibly resulting in minor misalignments. Hence, once the prosthetics are installed, there may be visually imperceptible misalignments between the prosthetic acetabular cup and the prosthetic femoral head. This may result in problems such as misalignment of the leg, incorrect leg length and/or incorrect soft tissue tension. Additionally, in the long term, misaligned prosthetic components may wear more quickly, giving rise to aseptic loosening of components and potentially necessitating early repetition of the surgery.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
According to a first aspect of the present invention there is provided a surgical jig for application to a bone, said jig including:
According to a second aspect of the invention there is provided a surgical jig for application to a femur during hip replacement surgery, said jig including:
Preferably the at least one lug is a rod disposed on a head of the jig so as to define an end adapted to engage a femoral bone formation and thereby position said one or more slots in a predefined relationship to said femoral bone formation.
Also preferably the jig further includes contours disposed on a base of the head, said contours matching, and being adapted to mate with, a femoral bone formation.
According to a third aspect of the invention there is provided a method of performing hip replacement surgery on a patient, said method including the steps of:
Preferably the first femoral bone formation is a greater trochanter and the second femoral bone formation is a femoral neck.
In the preferred embodiment the method also includes combinations of the following steps:
According to a fourth aspect of the present invention there is provided a method of performing hip replacement surgery on a patient, said method including the steps of:
Preferably said one or more of said spacers include markings adapted to indicate said reference positions. Also for preference, step vii) includes determining a center of said reference positions and using said center as a center of reaming.
According to a fifth aspect of the present invention there is provided a method of performing hip replacement surgery on a patient, said method including the steps of:
F) correlating the number or size of spacers with a required prosthetic component size.
Preferably said required prosthetic component size relates to a neck length of a prosthetic femoral neck and head component. Also for preference, at least some of the spacers have a thickness corresponding to size increments between prosthetic components.
According to a sixth aspect of the present invention there is provided a method of performing hip replacement surgery on a patient, said method including the steps of:
E) applying one or more spacers to the first end of the stem so as to determine a required orientation of the acetabular cup relative to the stem.
According to a seventh aspect of the invention there is provided a spacer for use in hip replacement surgery, said spacer including:
According to an eighth aspect of the invention there is provided an alignment handle for use in hip replacement surgery, said alignment handle including:
Preferably the referential system includes a local gravitational field.
According to a ninth aspect of the invention there is provided an alignment frame adapted for use with an alignment handle as described above, said alignment frame including:
Preferably the planar surface is a side of an operating table.
According to a tenth aspect of the invention there is provided a method for extracting an osteotomitised femoral head from a patient's hip joint, said method including one or both of the following steps:
According to an eleventh aspect of the invention there is provided a method for inserting a prosthetic acetabular cup into a patient's reamed acetabulum during hip replacement surgery, said method including the steps of:
According to another aspect of the invention there is provided a method for ascertaining a size of a prosthetic neck length during hip replacement surgery, said method including the steps of:
Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIGS. 9 to 16 inclusive are depictions of steps involved in a method of performing hip replacement surgery according to the preferred embodiment of the present invention, with
FIGS. 59 to 62 are plan views of screws;
Referring to
The jig 1 includes jig location means 6 adapted to mate with bone formations 3, 4 and 5 so as to locate the jig 1 in a predefined relationship with the bone 2. The jig 1 further includes surgical tool guide means 7 disposed relative to the jig location means 6 such that, when the jig 1 is mated with the bone formations 3, 4 and 5, the surgical tool guide means is adapted to guide a surgical tool, for example a reciprocating blade, towards a predefined site on said bone formation.
The jig 1 includes a body 8. One aspect of the jig location means 6 takes the form of first and second opposed lugs 9 and 10 disposed on the body 8. The lugs 9 and 10 are adapted to mate with the femoral neck 4. Each of the lugs 9 and 10 have an elongate dimension oriented such that, when the jig 1 is mated with the femoral neck 4, the elongate dimension of the lugs 9 and 10 is oriented in substantially the same direction as an elongate dimension of the femoral neck 4. This is best shown in
Another aspect of the jig location means 6 is a surface 13 adapted to receive a bone formation, for example a femoral head 3. In the preferred embodiment the surface 13 defines an inverted V shape, as best shown in
Yet another aspect of the jig location means 6 is a side wall 17 of the body 8 shaped so as to mate with a bone formation. More particularly, the side wall 17 is arcuate with a curvature shaped so as to abut a natural curvature of the greater trochanter 5. The line along which the side wall 17 substantially abuts the natural curvature of the greater trochanter 5 is best depicted by line 18 on
Hence the preferred embodiment of the jig 1 shown in FIGS. 1 to 5 mates with bone formations on the femur 2 via:
These location means combine to ensure that the jig 1 can be accurately placed onto the femur 2 and maintained in position to assist with aligning the osteotomisation of the femoral neck 4. Alternatively, the jig 1 may be oriented the other way around, with the inverted V shaped member 14 against the femoral neck 4 and the lugs 9 and 10 against the femoral head. This maybe further secured by driving one or more fasteners such as pins through body 8 or lugs 9 and 10 into the femoral head 3. Of course, damage to the femoral head 3 resulting from the fasteners is of little concern since the head 3 is to be osteotomised. The pinning of the jig 1 to the femoral head 3 can then be used to assist in removing the femoral head after the cut has been made, as discussed in more detail below.
The surgical tool guide means 7 is disposed intermediate the inverted V shaped member 14 and lugs 9 and 10. This assists in guarding against rotation or displacement of the jig 1 due to forces that may be transferred from the surgical tool to the jig 1. The surgical tool guide means 7 takes the form of one or more slots 20 disposed within the body 8. The preferred embodiment has three slots 20. Each slot is disposed at a different lateral position on the body 8 so as to allow the slots 20 to guide a surgical tool to more than one predefined site on the bone formation. The predefined sites are selected so as to correspond with different sized prosthetics. For example, one type of prosthetic requires the femoral neck 4 to be osteotomised at a position 1.5 cm from the base of the greater trochanter 5 and hence one of the slots 20 is disposed so as to guide the surgical tool toward this position. Each of the slots 20 extend transversely across the body 8 and are adapted to receive and guide a surgical tool, for example a reciprocating blade such as a jig saw. The positioning of the slots 20 once the jig 1 has been mated to the femur 2 is shown by lines 21 on
Although not shown in FIGS. 1 to 4, the preferred embodiment includes a handle disposed on said body 8. The handle has a length sufficient to extend externally of a patient when the jig 1 is mated to the bone formation. This allows the surgeon to manipulate the jig 1 past the flesh of the patient to mate with the femur 2.
The preferred surgical method according to the present invention is particularly suited to hip replacement surgery in the cases of osteoartritis, rheumatoid arthritis and osteonecrosis. However it is generally not recommended in the following circumstances:
During the preferred method of performing hip replacement surgery on a patient a postero-lateral surgical approach is preferred, although other surgical approaches will also suffice. Indeed, other surgical approaches may be necessitated if the postero-lateral surgical approach is contra-indicated, for example due to previous severe sciatic nerve injury.
The preferred method commences with step a)—exposing a greater trochanter 5, and femoral neck 4 of the patient. This entails making an initial incision in a thigh of the patient of between 3 cm and 7 cm, preferably 5 cm, in length. One end of the incision commences approximately 1 cm to 3 cm behind the greater trochanter 5 and curves backwards therefrom. The posterial aspect of the femoral neck 4 is exposed by detaching a tricipital tendon of the patient, which may be tagged for later re-attachment. A capsulectomy is also performed to fully expose the femoral neck 4. It is important to note that the femoral head 3 is not dislocated at this stage. The leg of the patient is maintained in a position approximately 45° from vertical, preferably by a leg holder. It may also be of assistance for the surgeon to make use a head light.
Step b) involves applying a jig 1 having surgical tool guide means 7 to the femur 2 such that the surgical tool guide means 7 is proximal the femoral neck 4, as shown in
Optionally, the surgeon may form a notch 22 in the femoral neck 4 on the femoral head 3 side of the osteomological cut site 26. The notch 22 is preferably formed prior to the osteomological cut. The notch may be formed by briefly impacting a reciprocating jig saw blade against the femoral neck 4 or head 3.
Step c) involves using the surgical tool guide means to guide a cutting tool so as to osteotomise the femoral neck. Typically the blade of a jig saw is fed through one of the slots 20 so as to rest against the femoral neck 4 at the osteotomological site, although other cutting means may be employed. The jig saw is then turned on causing the cutting blade to reciprocate and the jig saw blade is progressively moved transverse to the femoral neck 4 as guided by the slot 20 until the femoral head 3, and part of the femoral neck 4 are osteotomised.
Step d) entails removing a severed femoral head from the patient's hip joint. A number of different techniques may be employed to achieve this. For example a scoop 23 as shown in
An alternative method for removing the femoral head 4 may be employed if the jig has been fixed by pins to the femoral head 3 as mentioned above. In this case force may be applied to the jig 1 which is transferred through the pins to the femoral head 3. In some cases this force alone may suffice to remove the femoral head 3 from the hip joint. In other cases this force may assist other removal means, such as the scoop 23 mentioned above.
It will be appreciated by those skilled in the art that osteotomising the femoral neck 4 prior to removing the severed femoral head 3 advantageously avoids the prior art requirement to firstly dislocate the hip joint, thereby avoiding or minimising the damage this can inflict, and simplifying the surgical procedure. Following removal of the severed femoral head 3, the hip replacement surgery may be completed in accordance with prior art techniques. However a number of further improvements to the known surgical procedure are outlined below.
A prior art method for implanting a prosthetic stem into the femoral shaft involves driving a bone compressor into the femoral canal. An alternative provided by the preferred embodiment of the present invention includes the steps of:
The prior art method for reaming a cavity into the acetabulum involves aligning the reaming tool by eye. In contrast, the step of reaming the acetabulum to accept a prosthetic acetabular cup according to the preferred embodiment of the present invention includes the steps of:
More particularly, examples of the spacers 35 used in step i) are as shown in
The center of the reference points 36 established in step j) provides the starting point for reaming of the acetabulum in step k). This provides a more accurate and consistent alternative to the prior art reaming technique whereby the alignment is performed by eye.
Other example of spacers 100 which may be employed in steps i) and j) are shown in FIGS. 20 to 24. These spacers 100 include an outer circumferential edge 123 having a radius of curvature substantially corresponding to a radius of curvature of a prosthetic acetabular cup 104. In the preferred embodiment the radius of curvature of the outer circumferential edge 123 matches a radius of curvature of the smallest of a range of prosthetic acetabular cups 104. At step j) the surgeon uses the edge 123 as a guide when burning reference points 36 onto the acetabulum prior to the reaming of step k).
The prior art hip replacement surgical method involves the surgeon making an educated estimate as to the required size of prosthetic components, such as prosthetic neck/head length and acetabular cup size. Then the hip joint is temporarily assembled using trial components having the estimated size. If the resultant trial joint is not satisfactory, for example due to incorrect tissue tension, the joint is disassembled and differently sized trial components used. The preferred method of the present invention provides an alternative to this prior art procedure by once again utilising the spacers 35. As best shown in
Other embodiments of spacers 100 adapted to control the anteversion of the prosthetic cetabular cup 103 are shown in FIGS. 20 to 24. The spacer 100 includes a handle 101 defining a first end 102. Alignment means 103 are disposed at, or adjacent to, the first end 102. The alignment means 103 is adapted to mate with a prosthetic acetabular cup 104 such that, in use, the cup 103 is positioned in a predefined relationship with reference to an acetabulum of a patient.
The alignment means 103 defines a plane 105 adapted to abut a corresponding plane 106 of the prosthetic actabular cup 104. The alignment means 103 includes engagement means taking the form of one or more lugs 119 adapted to engage an internal concave surface 120 of the prosthetic acetabular cup 104. The plane 105 is defined by a semi circular surface 107 and is disposed at an acute angle 111 with reference to a plane 112 defined by the handle 101. Hence, the alignment means 103 takes the form of a wedge shaped member 110 disposed at the first end 102. Preferably the angle 111 is within the range of 5° to 25°. More preferably the angle 111 is within the range of 10° to 20° and in the preferred embodiment the angle 111 is approximately 15°. This angle 111 is chosen so as to correspond with a natural angle of inclination of the hip joint.
In the preferred embodiment the geometry of the alignment means with reference to the handle is chosen to be appropriate for a postero-lateral surgical approach to hip surgery. Of course, other surgical approaches may necessitate slightly varied geometries, for example the different handle geometry shown in 23 as compared to
The alignment means 103 includes a slot 108 which is adapted to receive a protruding end 34 of a prosthetic femoral stem 33. Once the end 34 of the stem 33 is placed inside the slot 108, the spacer 100 engages the stem 33 in a similar manner to the way in which spacer 45 engages the stem end 34 in
The angular inclination of the prosthetic acetabular cup relative to the prosthetic stem 33 should mirror the natural geometry of the hip joint as accurately as possible. As the spacer 100 is rotated about an axis of rotation 118, the direction of the 15° angular inclination changes. To provide the surgeon with guidance as to whether the alignment means 103 is positioned in said predefined relationship with reference to an acetabulum of a patient, an orientation guidance means 109 is disposed upon the spacer 100 at or adjacent to second end 113. The orientation guidance means 109 includes a plumb bob 114 rotatably disposed upon the spacer 100 so as to hang substantially vertically under the influence of gravity. The plumb bob 114 is rotatably affixed to a circular member 115 of the spacer 100 by a pin 116. A reference point 117 is disposed on said spacer 100 such that the plumb bob 114 hangs in alignment with the reference point 117 when the alignment means 103 is positioned in said predefined relationship with reference to an acetabulum of a patient. In other words, when the spacer 100 has assumed the required rotational position with regard to axis of rotation 118, the plumb bob 114 hangs in alignment with the reference point 117, as shown in
The surgeon determines in step o) whether a required fit between the trial head 41 and the trial acetabular cup 42 has been obtained by examining factors such as the tissue tension, component alignment, leg length, etc. Once the required size of the prosthetic component has been determined in step n) the trial prosthetic components 41 and 42 (
The instruments illustrated in FIGS. 25 to 65 collectively form a preferred embodiment of a kit for performing the preferred surgical procedure. This preferred surgical procedure commences with positioning the patient in the lateral position with the operative side uppermost as best shown in
Exposure of the operative site commences with an approximately 5 cm long incision along a line 231 which is made approximately 2 cm behind the prominence (shown as line 232 in
The leg is placed in a leg holder and maintained at approximately 45 degrees to the vertical. The surgeon grasps the jig 140 by its handle 141 and manipulates the head 210 of the jig through the patient wound and onto the femoral neck 4, as best illustrated in
The first version of the jig 140, as shown in
Additional jig location means are provided by a surface 212 adapted to receive a bone formation. This surface 212 is provided by contours 146 on the base of the head 210 which are adapted to mate with contours of the femur.
Once the jig has been correctly positioned, fixing means such as pins, 143, as shown in
The slot 143 is oriented at an acute angle to the elongate dimension of the rod 142, with the angle being dependent upon the required angle of cut to suit the particular prosthetic components being used in the surgery. The slot 143 functions as a surgical tool guide means which is positioned by the jig 140 at the correct position for osteotomisation of the neck 4. Advantageously, osteotomisation takes place whilst the femoral head 3 is still disposed within the acetabulum. The surgeon may also perform a secondary proximal wedge osteotomy if deemed necessary.
Subsequent to the osteotomisation of the neck 4, the femoral head 3 is folded forward then removed using one or more of a number of possible options. The drill 147, as shown in
For the next surgical step the leg of the patient is supported perpendicular to the operating table. The proximal femur is prepared in accordance with standard prior art techniques using a trocar awl and a guide. Pointed Hohmanns (that is, retractors) are placed on either side of the femoral neck 4. Alternatively a broad blunt Hohmann may be applied under the neck 4 so as to elevate the neck 4.
A bone compressor is mountable to the punch 153 at the driving surface 154 and is held in place by a pin 156. The bone compressor is driven into the longitudinal axis of the femur using the punch 153 by striking the proximal end 157 with a hammer, mallet or other suitable tool. This process forms a hollow in the femoral canal for subsequent installation of a stem 34 (see below). The driving surface 154 of the punch 153 is laterally displaced from the elongate longitudinal member 155 to allow the surgeon to more easily drive the bone compressor in the correct direction whilst negotiating and manipulating the punch 153 through the patient wound. This assists in minimising the risk that the bone compressor will be driven into the femur at an angle which may cause an outer edge of the femur to crack. A calcar reamer is then used to form a circular plane on the end of the neck 4. The femur is now ready for insertion of a prosthetic stem, which takes place after the insertion of the acetabular cup as described below.
The surgeon next positions the patient's limb in a neutral position on the operating table to prepare for reaming of the acetabulum. A pointed Hohmann is then placed over the anterior margin of the acetabulum. The acetabulum is then reamed in a stepwise manner using increasing diameters.
To insert the prosthetic acetabular cup into the reamed acetabulum, a cup alignment tool 167 is assembled from the following three components: the alignment handle 159 shown in
Either the left or the right cup holder 158, as required, is attached to the alignment handle 159 via attachment means 160 disposed on a proximal end 164 of the cup holder 158. More particularly, the attachment means 160 includes a projection 169 which keys into the connector on the distal end 161 of the alignment handle 159 to ensure correct relative alignment between the two components. Once keyed into each other, the internally threaded collar 163 engages the external thread 224 on the cup holder 158 to secure the two components together.
The handle 213 provides the surgeon with additional leverage when manipulating the cup alignment tool 167. To connect the handle 213 to the cup holder 158, an external thread 163 on the handle 213 threadedly engages an internal thread 162 disposed within the cup holder 158. The resulting cup alignment tool 167 is as illustrated in
The next step is to attach a prosthetic acetabular cup of appropriate size onto the cup alignment tool 167. Depending upon the size of the prosthetic acetabular cup, a spacer 174, 215 or 216 may be required. Spacers of various widths, as illustrated in FIGS. 37 to 42, are engagable with a first end 168 of a boss 176 which is disposed on the distal end 165 of the cup holder 158. More particularly, a projection 166 disposed on the spacer 174 is press fittingly engagable with a corresponding aperture 214 provided in the first end 168 of the boss 170.
The surgeon selects a spacer 174, 215 or 216 having an appropriate width to match the size of the prosthetic cup being inserted into the patient's hip. For the smallest prosthetic acetabular cup no spacer 174 is required. The spacers 174, 215 and 216 are consumable items made from a plastics material which is designed to withstand only a single operative use. The kit of instruments includes four screws 217, 218, 219 and 220 with differing lengths as illustrated in FIGS. 59 to 62 respectively. Hence, this screw and spacer arrangement caters for four sizes of prosthetic acetabular cup respectively corresponding to:
Preferably the screws 217, 218, 219 and 220 feature an allen head socket 221. Each screw has a length which is just sufficient to extend axially through the aperture 214 of the boss 170, with the head 222 of the screw adjacent the second end 171 of the boss 170 and the threaded end 223 emerging just past the first end 168 of the boss 170 and also just past whatever spacer 174, 215 or 216 may be engaged with the first end 168. The emerging tip of the threaded end 223 is threadedly engagable with the prosthetic acetabular cup 104. In this way the prosthetic acetabular cup is mounted onto the cup alignment tool 167. More particularly, the acetabular cup is engaged with the cup holder 158 such that a concave face of the acetabular cup faces towards the second end 171 of the boss 170.
The surgeon then manipulates the cup alignment tool 167 into the wound 234 as shown in
The gauge 172 has a needle 173 which functions as a plumb bob. The needle 173 is rotatably disposed on the alignment handle 159 so as to hang substantially vertically under the influence of the local gravitational field. The gauge allows the surgeon to correctly align the acetabular cup in at least a first plane by positioning the cup alignment tool 167 such that the rotatable needle 173 of the plumb bob 172 is aligned with a reference point in the form of the fixed needle 175.
The alignment frame 176 shown in
Engagement means in the form of a slotted member 181 is disposed on the second end 179 and is aligned so as to project toward the patient's hip. The open-ended slot 225 in the slotted member 181 defines a semi circular surface 226 having an internal radius of curvature which matches an external radius of curvature of the body 182 of the alignment handle 159. In other words, the slot 225 is sized so as to receive and direct the body 182 of the alignment handle 159. The geometry is such that engagement of the alignment handle 159 with the engagement means 181 forces the alignment handle 159 into a predefined orientation with respect to a second plane (different to the first plane associated with the plumb bob 172). This is because the slotted member 181 has a width 227 sufficient to ensure that when the body 182 is engaged with the slotted member 181, the longitudinal axis of the body 182 matches the axis of the slotted member 181. More particularly, when the body 182 is disposed within the slotted member 181, the body 182 is substantially perpendicular to the side of the operating table.
Preferably the hip of the patient is maintained on the operating table in a predefined position relative to the operating table, for example by using a pelvic holder 230 and/or other means for fixing the patient's position on the operating table. When each of the following conditions are met:
At this point the surgeon utilises the punch assembly 183, as illustrated in
The fastener driver 187 is preferably an allen key, as illustrated in
If desired, the acetabular cup can be optionally further affixed into the reamed acetabulum by fixing means such as a screw which is driven through the acetabular cup and into the patient's pelvis. A liner is then inserted into the acetabular cup and a blunt Hohmann may be inserted under the liner to avoid subsequent displacement.
The patient's leg is now held in a vertical position to allow for insertion of the stem 33, for example a C.F.P. stem, into the femoral canal. After insertion, an end 34 of the stem 33 projects from the end of the femur.
It is now necessary to determine the prosthetic neck length required for post operative correct leg length, tissue tension and muscle tension. A short trial head is placed onto the stem and the hip joint is reduced. As best shown in
The spacer member 190 includes a spacer 194 which has a slot 195 adapted to engage an end 34 of the stem 33. This positions the spacer 194 intermediate the trial head and the end 34 of the femur, as shown in
With the spacer 194 in place, the surgeon tests whether the leg length and/or tissue tension and/or muscle tension are sufficient. If not, the surgeon extracts the spacer alignment tool 189 and clips a medium width additional spacer 196 (as illustrated in
In other words, the testing process is repeated with spacers 194, 196 or 197 of different thicknesses (or with a different number of spacers) until the anatomically correct leg length and/or tissue tension and/or muscle tension is achieved. The surgeon then takes note of the spacer thickness (or number of spacers) which gave the best results and correlates this with the required prosthetic neck length in accordance with a predefined correlation scheme. For example, if the correct leg length and/or tissue tension and/or muscle tension is achieved without the need for an additional spacer 196 or 197, then the shortest prosthetic neck length is used. If the correct leg length, etc, is achieved with the use of the medium thickness additional spacer 196, then a medium prosthetic neck length is used. If the correct leg length, etc, is achieved with the use of the thick width additional spacer 197, then the longest prosthetic neck length is used. Of course, other correlation schemes may also be devised for other embodiments of the invention.
This process for ascertaining the prosthetic size required to give the correct leg length, etc, is preferable to the prior art method which involves repeatedly dislocating the hip joint until the correct size of prosthetic components is identified.
The hip is dislocated and the test prosthetic components are now replaced with the actual prosthetic components and the hip is reduced. The surgeon now confirms that the patient's leg has the proper range of motion and double checks that acceptable leg length, tissue tension and muscle tension have been achieved. The surgeon concludes the operation in the standard manner by re-attaching the tricipital tendon and short external rotators and closing in the various layers. The application of a cryocuff to the hip region is recommended to aid post operative rehabilitation.
The pin extractor 199 may be utilised if it is desired to salvage the pins 143 which were previously driven into the femoral head 3 and remain embedded within the femoral head 3 once it has been removed from the patient. Also, it may be necessary to conduct tests on the femoral head 3, in which case removal of the pins 143 may be required. With the tongs 200 and 201 radially separated, a pin 143 may be inserted into aperture 202, past engagement member 203. The tongs are then squeezed radially together such that the engagement member 203 exerts a transverse force onto the notches 228 disposed adjacent the end 229 of the pin 143, thereby causing the pin extractor 199 to grip the pin 143 tightly. A longitudinal force is then exerted upon the pin extractor 199 which is transferred to the pin 143 to assist in extraction of the pin 143 from the severed femoral head 3. The longitudinal force may be supplied by impacting a hammer onto projection 204.
It will be appreciated that the preferred method for hip replacement surgery provides a number of advantages in comparison to the prior art methods. In particular, the hip joint does not require dislocation prior to the oesteotomy, the accuracy and consistency of the reaming of the femoral canal and acetabulum is improved and the process for establishing the required sizing and orientation of prosthetic components generally entails less trial and error. Typically this results in a surgical procedure in which the paiient's ligaments and muscular attachments experience minimal disturbance, allowing for more rapid patient rehabilitation with less postoperative pain. Further advantages typically associated with the preferred embodiment include reduced scarring, reduced blood loss and clotting, reduced risk of infection, shorter hospital admittance and reduced costs.
Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.
| Number | Date | Country | Kind |
|---|---|---|---|
| PR 8657 | Nov 2001 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AU02/01482 | 11/1/2002 | WO |
