ENGAGING'. ANCHOR PT

BACKGROUND

[0001 ] The present invention relates to soft tissue retractor blades for u e in surger and more particularly relates to a retractor blade have a distal end formation which is capable of reieasahle engagement with a bone anchor and which thereby moves with the anchor while engaged in retraction and contributes to resist unwanted withdrawal. More particularly, the invention relates to a retracting Made having a distal end geometry which engages a pin anchor locatable in vertebral bone during retraction of soft tissues to enable safer, more convenient, and efficient retraction of those tissues. The invention further provides a retraction blade having a fonriatioii at a distal end which at least partially engages a anchor pin via a recess which receives and retains the retractor. The invention farther provides a. retractor blad in which the distal end formation, allows retraction of veins and arteries and other soft tissues during spinal surgery while in engagement with a bone pin. Although the invention is to be described below in relation to spinal vertebra the principles and geometry embodied in the retractor blade have applications wherever bone pin anchors or the like ar e used.

PRIOR ART

[0002] Ther are in existence retractor blades which retract soil tissue during spinal surgery. Such retractor blades ar e maintained at a setting to allow a surgeon access to a spinal disc space and vertebrae in procedures such as cervical and lumbar spinal disc surgery. Retractors are also used in operations requiring distraction of spinal vertebra _* The process of axial separating spinal vertebr is termed distraction. This involves insertion of a spreading type instrument into an excised disc space which engages the upper and lower vertebral bodies and when applied separates them. This is known as intervertebral distraction. [0003] Alternatively, in the cervical spine, a procedure known as non - intervertebral distraction may be used in which long screws are inserted into the upper and lower vertebral bodies. Surroundin soft tissues must be held apart by retrac tors. Once retracted, there is a natural elasticity of the stretched tissues tending to wound closure, so it is essential to employ retractors which effectively restrain soft tissues to allo clear access to a surgical site.

[0004] It is important to reduce trauma to soft tissues which may occur from contact with parts of retractor blades so that the surgical procedure is as minimally invasive as possible and thus minimally interferes wi th and minimally traumatizes the organs, tissues and vasculature being displaced to allow access to the vertebral region being treated. Various known retractor blades each have a. different geometry but similar purpose and fundamental form. Each are typified in having means at first end for engaging a support assembly or being manually held during an operation, a return body portion and a distal or second end which is capable of engaging bone or soft tissue, thereby providing a point of leverage and contributing to retraction and support of the blade during retraction. The design objective with retraction blades are _. primarily, optimal stability and safe and efficient retraction of soft tissue.

[000S] Whatever level of surgery is being performed, there is an initial approach requiring some degree of vascular dissection. The approach and surgery generally requires the use of at least handheld retractors, at least initially, which may then be replaced with fixed retractors to maintain retraction for the rest of die procedure.

[0006] Fixed retractors require eithe internal fixation to spinal vertebra or external fixation using a table mounted system. Retractors are usually positioned to hold tissues away from the surgical field both laterally (side to side) and longitudinally (up and down) relative to a spine. Existing retractors may be internally or externally fixed. Internal fixation of retractors is utilized to hold the left common iliac vein or other ti ssues in a retracted position . Due to the di fficulty and dangers of moving and keeping the blood vessels retracted during some surgeries such as anterior lumbar surgery, stability of the retractors is particularly important. There is a danger that veins may be punctured or squeezed.

[0007] The most stable retractors are those embedded in the bone e.g. Steinman pins and Hohttiarm retractors. Hohmann retractors are conventional retractor blades with a carved pointed end which can be impacted into the bone for stability. Steinman pins are long pins impacted into the bone. Some limited movement of the Hohmarm blade is possible by bending. Also known are standard retractor blades that have a channel that allow separate introduction of sharp pins through the channel into the vertebral bod thus securing the blade to the spine.

[0008] internally fixed retractors have limitations. Although very stable once in place they are not adjustable and insertion does produce bone injury. Insertion and removal can also be hazardous to vessels or other soft tissues.

[0009] There are table based systems, that offer a variety of retractor blades for holding back the tissues connected to a table mounted ring or suppor frame. Various shapes of blade are available. In order to improve on these and in particular to improve stability of these non internally fixed blades a new shape of retractor blade, called The Brau Blade, was developed. This blade is described in US patent number 6,416,465 which is incorporated by reference herein.

[0 10] The Brau device is characterised in having a forward directed lip of tire di stal tip of the blade that curves forward away from the plane of the blade in an opposite direction to that of the handle, i.e towards tire spine. This has a gently curved point or blunt lip that contacts the side of the spine and provides more stability than alternative blades during insertion of the retractor and possibly maintenance of retraction. It also has ridges hi the Hp to increase purchase with the side of the vertebral body or disc.

[0011] The lip of the Bran blades and all other conventional blades when used for lateral retraction are in contact with the ^' bone along the side of the body i.e. in contact with the spine along a superior inferior plane. T remain stable they rel on a solid immobile connectio to the operating table through various linkages and ^' if in contact with the bone, a force directed along the edge of the bl ade (the lip) parallel to this radius of the body. This stability is easily achieved when held in the hand, but not when attached to an external frame because of the moment arm from the end of the blade to the fixed anchorage at the side of the table: (see assembly of Figure I below).

[0012] Man conventional blades sit beside the bone with a lip curving away from the bone. Contact with the bone provides an additional point of stability. There are disadvantages with retractors which rely on support frames and those that rely on a sharp end or some other ermina ion which engages bone, if a constant force is applied from the frame along the line of the blade, pushing the blade against the spine helps stability, but this can easily lead to the blade slipping or sliding posteriorly and causing tissue injury whe the spine moves. Inadvertent downward pressure by surgeons or their assistants on these blades also is a problem as it lead to posterior displacement., because there is litt le or "no su pport for the blad e from the bone relying as it dies essentially o friction grip. Thi can lead to soft tissue injury in the regio in which th surgery i performed.

[0013] When retracting longitudinally using retractor blades, the edge of the blades can be pushed down onto the of the vertebral bodies where they are lying across the spine. This gives them much greater relative stability: One of the limitations of existing retraction system is the tendency for the vessels, to bulge around the retractor, which can expose the vein to injury and impede the surgeon. Excessive retraction can lead to direct vessel injury, bleeding or thrombosis, and irregular retraction. It is desirable to minimiz the amount of retraction used and to use smooth retraction over an area, particularly when retracting blood vessel in order to reduce turbulence and thereby the potential for thrombosis within the vessel.

[0014] Numerous retractor blades exist for use in. surgery of various shapes and geometry. For example one a hand held retractor blade is known with, two surfaces at right angles to each other over the length of the blade. The end is shaped for bone contact.

[0015] There are other blade assemblies in. the prior art such as that disclosed in US patent number 6,692,434 which discloses a method and device tor retractor for microsurgical intermuscular lumbar arthrodesis. Qne blade is bent at an end portion thereof in a direction awa from the handle portion. The other blade has first and second blade faces, with the second face having at least two toothed structures located thereon.

[0016] A combined distracter and retractor instrument for use during a spinal surgery procedure is disclosed in US patent application No. 20050154395. The surgical instrument disclosed is configured to distract two adjacent vertebral elements and retract the nerve root to provide access to the distracted site. The instrument includes a elongated blade member having a wing located on an edge of the blade member, and a handle. This instrument is primarily for use in posterior access to the spine. The instrument has some soft tissue retracting capacity but is restricted in its use as it must be held by such persons as assistants and once located .between vertebra must be rotated to procure any retraction.

[0017] Although there are a variety of retractor blades currently in use, in view of the disadvantages inherent in those blades, there remains room for improvement in the geometr of the blades with the objective of providing a blade which is easy to use, efficiently maintains retraction of soft tissue and does not obstruct the surgeons path to the operating site and does not compromise retraction in the event of un anted loading such as inadvertent bumping during surgery.

i VENTlO [0018] The present invention provides an alternative to the known retractors seeks to improve- the disadvantages of the prior art by providing a retractor blade including a distal end profile which detaehably engages an anchor pin.

[0019] Outlined broadly below are embodiments and features of the invention to enable the invention to be better understood, and in order -that the present contribution, to and improvement over the current the art may be better appreciated. There has thus been outlined, rather broadly, the mor important features of the invention in order that the detailed description thereof that follows may not only be better understood, but in order that the present contribution to the art may be better appreciated. There are, of course, addi tional features of the invention that will be described hereinafter and which will, form the subject matter of the claims appended hereto.

[0020] In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth i the following description or illustrated i the drawings. The invention is capable of othe embodiments and of being practiced and carried out in various ways in various rescue circumstances. Also, it i to. be understood that the phraseolog and terminology employe herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis tor the designing of other variations on the assembly, structures, methods and systems for carrying out the purposes of the present invention,

[0021] It is therefore an object of the present invention to provide a new and improved device which removes the practical disadvantages encountered using current devices and techniques. In this respect, before explaining at least one embodiment of the invention in detail , it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the followin description or illustrated in the drawings-- The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

[0022] The term retraction when used throughout this description can be taken to mean, displacement and retention of soft tissues which occurs during surgery to assist access to an anatomical region. Throughout the specification, a reference to a retractor blade will include a reference to a device, member, am , plate, rod, restraint or the like which is engaged in the retraction of soft tissues in an anatomical structure of a human or animal.

1 23} This retractor according to the raveution seeks to improve the stability of retractor blades durin spinal surgery by distal end engagement with bone anchor pins. The invention provides an alternative distal end blade shape that improves retraction and resists more effectively any distal end bi directional displacement daring surgery which would otherwise result in less efficient retraction compared to existing retractor blades. The formation has the appearance of a toe or tab extending from a location adjacent or near the distal end of the retractor.

[0024] hi its broadest form the present invention comprises: a retractor blade comprising a blade body having first and second ends, the first end including means to allow connection of the blade body to a support member or allow manual gripping, the second end comprising at least one formaiion which allows releasable engagement with a vertebral bone anchor pin, the second end formation including a recess which receives and retains therein said bone anchor pin such that the retractor is able to move as said anchor pins move during distraction. [0025] According to a preferred embodiment the second end is distal and comprises a first part disposed in a first orientation and a second part disposed normally to the first part, the second part including an opening which defines an internal space which receives and retains said anchor pin,

[0026] In another broad form the present invention comprises:

a surgical retractor blade for refraction of soft tissue during spinal surgery, the blade comprising: a generally elongated planar blade body having first and secon d ends, the first end providing means for connection of th b lade body to a support member or which enables manual gripping by a user, the second end being a distal end comprising at least, one formation which extends from the distal end of the blade and which each include a recess which C operativeiy engage an anchor pin fixed i a spinal vertebrae; wherein the engagement between the pin and formation allows the retractor to move with the anchor pins during distraction of spinal vertebrae and to resist unwanted displacement of the retractor blade during retraction or distraction,

[0027] In another broad form the present invention comprises: retractor blade for retracting soft tissues during spinal surgery, the retractor comprising;, a blade body having first and second ends, the first end providing a free non working end and the second end comprising a first part disposed in a first and a second part disposed normally to the first part and including at least one hook like formati n which at least partially extends about a vertebra! anchor pin sufficient to said orientation allow the retractor to move in co operation with the anchor pin during retraction of vertebral bone.

[0028] According to a preferred embodiment the formation includes a side opening which receives the anchor pin and a return which surrounds the pin sufficient to avoid separation between the formation and pin during distrac tion. [0029] The first part in the first orientation is a transverse distal edge which is part of th blade body. The second part engages the first pail via a connection whic is preferably integral wit the blade body. Preferably, the formation which engages the anchor pins is defined relative to X, Y and Z axes, wherein the X &Y axes are normal to each other and to the Y axis. According to one embodiment, the formation is disposed at or near a outside edge of the blade with the formation extending normally and outwards from a plane of the blade along a Y axis and forms- a eaiitilevef. According to one embodiment, the formation engages the retractor blade at a location offset from the longitudinal axis and at a junction between a side and distal edge of the blade. The formation may extend from the blade for a distance within the range of 5mm - 25mm and an opening to the recess faces in a direction away from the longitudinal axis. Preferably the fomiation is integral with the blade body. The retractor blade recess has long dimension along the Y axis normal to a plane of the blade and which is within the range of 5~25mm. The recess has short dimension normal to the long dimension and which is within the range of 5mm to 13mm. The formation preferably has a thickness within the range of 1mm - 8mm.

[0030] In a alternative embodiment the retractor blade body has one or more angled sections which determine the blade body contour and allows the blade to fit soft tissu anatomy. The blade body may assum alternative shapes for strength or orientation as required for a particular anatomy. In a further embodiment the formation which engages the anchor pins comprises a generally L shaped termination at the distal end which is integral with the blade body. This may be formed by an abbreviation of the length of the blade for par t of the blade body width, The engaging profile may be pressed from a plane of the blade body to form a tab which is bent to an angle to suit the particular circumstance of pin engagement. Recessed ma be pressed into the tab prior to bending. [0031 In another broad form the present invention comprises: a retractor blade for retracting soft tissues during spinal surgery, the retractor comprising: a blade body having first and second ends, the first end providing means to allow connection of the blade body to a support member or to allow manual gripping, the second end comprising a canrilevered formation extending away from the blade body and including at least one recess which is capable of receiving and. retaining a bone anchor pin such that the formation co operates with the pin to restrai unwanted withdrawal of th retractor and allowing the retractor to move in unison with anchor pins during distraction of Spinal vertebra.

[0032] According to an alternative embodiment., the formation at. the working end of the retractor blade is formed i and is integral with the body of the blade and formed by a return portion at the distal end of the blade, in another embodiment, the formation is releasabl connected to the blade allowing an operator to select working formations according to surgical requirements. Preferably, the body of the blade is manufactured from a substantially planar plate which is angled or curved to accommodate anatomy in particular surgical site.

[0033] The present: invention provides an alternative to the known prior art and the shortcomings identified. The foregoing and other objects and advantages will appear from the description to follow. In the description reference is made to the accompanying representations, which forms a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the. accompanying illustrations, like reference characters designate tire same or similar parts

1.0 throughout the several views. The following detailed description is, therefore, not to be take in a limiting sense, and the scope of the present invention is best defined by the appended claims. It will be convenient to hereinafter describe the invention in relation to metal blade i the present exemplary application, but it is to be appreciated that the invention may be manufactured from other materials or combination of materi als.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will now be described in more detail according to a preferred embodiment but noti limiting embodiment and with reference to the accompanying illustrations , wherein :.

Figure 1 shows a perspective view of ¾ retractor blade according to a preferred embodiment in a first orientation.

Figure 2 shows a perspective view of a retractor blade according to a preferred embodiment; in a second orientation.

Figur 3 shows a front elevation view of a retractor blade engaging an anchor pin in a spinal vertebrae.

Figure 4 shows a perspective view of a retractor blade accordin to an alternative embodiment.

Figure S shows a side elevation view of the retractor of figure 4.

Figure 6 shows plan vie of the retractor of figure 4.

Figure ? shows a front v iew of the retractor blade of figure 4.

Figure 8 shows an enlarged but abbreviated side elevation view of the distal end of the blade of figure 4.

Figure 9 shows a perspective view of a retractor blade according- to an alternative embodiment.

1.1 Figure 10 shows a plan view of the retractor blade of figure 9.

Figure 11 shows an enlarged view of the distal end formation ( circled A in figure 10) according to a preferred embodiment.

Figure 12 shows a cross sectional elevation through a spine having pins connected in vertebra and opposing retractors.

Figure 13 shows a plan view of the arrangement of figure 12 showing a connection regime for two retractors according to one embodiment

Figure 14 a,b,c show a schematic view of various angulations which may be applied to retractors described herein to accommodate various anatomical structures

DETAILED DESCRIPTION

[0035] Referring to Figure 1 there is shown a perspective view of a retractor blade 1 according to a preferred embodiment in a first orientation. Retractor blade 1. comprises a generally elongated blade body 2 having a first tree end 3 and second working end 4. First end 3 either provides means for connection to a support ( not shown) or is simply adapted for manrial operation. Second end 4 comprises a first part 5 oriented in a first directio and a second part 6 connected to the first part and disposed preferably normally to the first part, in a general sense the second part 6 is preferably normal to the orientation of the first part 5 but alternative embodiments are feasible. For instance the second part 6 may be disposed at an angle relative to either a horizontal or vertical angle to the first part S, The first part 5 terminates i an edge 7 and at or adjacent to edge 7 is at least part of edge 7 which incorporates a connection 8 to formation 9 at working end 4. Formation 9 mcludes a female recess 10 defined by a hook like profile 1 1 which receives and retains therein an anchor pin ( see figure 3 below).

[0036] Formation 9 in figure 1 is shown connected to part of edge 7. This may be formed in manufacture b a continuation o first part 5 by pressing and

1.2 forming of the required profile in formation followed by bending to a suitable angle as dictated by the anatomical environment in which the blade is used, i is preferred that formation 9 is integral with part 5 but it will be appreciated by persons skilled in the art that other forms of connection are feasible, m an alternative embodiment,, formation 9 may be detachable from part 5 and a vari ety of sizes and configurations- are envisaged

[0037] Edge 7 is when blade 1 is in use. disposed in an orientation which is essentially parallel to a longitudinal axis of a spine - see figures 3. The formation 9 extends from first part 5 and may be configured to suit a particular geometry according to the relationship between the edge 7 of blade 1 and the angulation required to enable formation 9 to engage an anchor pin. For example the angle of repose between the formation 9 and the blade body 2 may be a acut Or obtuse angle or normal to the blade i . The angle of repose of ^' formation 9 relative to end 4 dictates the approach angle to the anchor pins. Although one recess is preferred,, formation. -9 may comprise more than one recess which allow a user to select positioning of the retractor to align wit different slots with a position of an anchor pin to which it will be connected.

[0038 Figure 2 shows with corresponding numbering a perspective view of a retractor blade according to a preferred embodiment in a second ori en tation .

[0039] Figure 3 shows with corresponding numbering a tront elevation view of the retractor blade I engaging an anchor pin 21 in a spinal vertebrae 20. Formation 9 allows pin 21 to engage recess 10. it wil l be appreciated by persons skilled in the art that formation 9 may have alternate geometry to allows alternative means for engagement with pins 21 and 22. Fo instance, the location and a recess or recesses in formation 9 can be arranged to alter the approach direction from which the retractor blade may engage the pin 21. This may be achieved according to one embodiment by al teration of the position of the recesses in the formation 9. In one embodiment the recess can be formed by bifurcated -anas extending from the blade body.

[0040} An advantage of the blade according to the present invention is that the co operation between the anchor pins and the distal end formation 9 of the blade 3 prevents unwanted slippage or withdrawal of the retractor blade. Since the risk of unwanted displacement or slippage of the retractor is removed, there is less risk of soft tissue injury due to blade displacement during retraction, of vertebral distraction,

I (x 1 J The distal end formations described herein according to various embodiments may be adapted to known retractor blades or manufactured such that the formation is integral with the blade body. The size and geometry of the blade and profile of the fonnations is variable according to surgical requirements. For instance smaller sized retractor would be used for smaller patients and larger proportionate sizes for larger patients.

[0042} Figure 4 shows a perspective view of a retractor blade 30 according to an alternative embodiment Retractor blade 30 comprises a generally elongated but arcuate blade body 31 havin a proximal free end 32 and distal working end 33. Proximal end 32 either provides means for connection to a support ( not shown) or is simply adapted for manual operation. Distal end 33 comprises a first part 34 oriented in a First direction and a Second part 35 integral with the first part and forming a radiused curve which is intended to accommodate contours of patient anatomy. Third part 36 is flattened out and is disposed at 90 degrees to the first, part 34. This geometry is illustrative and is not to be taken as limiting of the various geometries which ma be selected to accommodate patient anatomies.

[0043] The Fust part 33 terminates in an edge 37 and at or adjacent to edge 37 alone, at least part of edge 37 is a hook formation 38 which includes a female recess 39 which receives and retains therein an anchor pin £ see figure 3). Fonaiation 38 is shown integrally connected at one side of retractor blade 30 to part of edge 37. This arrangement may be formed in manufacture by a continuation of first part 3.3 by pressing and forming of the require profile in formation 38 followed by bending to a suitable angle as dictated by the anatomical environment in which the blade is used. It is preferred that formation 38 is integral with first part 33 but it will be appreciated by persons skilled in the art that other forms of connection are feasible, lit an alternati ve embodiment, formation 38 may be detachable from edge 37 and a variety of sizes and configurations are envisaged.

[0044] Edge 37 is when blade 30 1 is in. use, disposed in a orientation which is essentially parallel to a longitudinal axis of a spine - see figures 3. The formation 38 is catnilevered from first part- 33 and may be configured to suit a particular geometry according to the relationship between the edge 37 of blade

30 and the angulation required to enable formation 38 to engage an anchor pin. For example the angle of repose between the formation. 38 and the blade body

31 may be an acute or obtuse angle or normal to the first part 33 of blade 30. The angle of repose of formation 3.8 relative to the plane of first part 33 dictates the approach angle to the anchor pins, in use when the blade 30 is retracting soft tissue, a distraction force is applied in the direction of arrow 40 to vertebrae ^■ via anchor pins, blade 30 is urged in the same direction.

[0045] Figure 5 shows with corresponding numbering a side elevation view of the retractor of figure 4. Figure 6 shows with corresponding numbering a plan view of the retractor of figure 4. Figure 7 shows wi th corresponding numberin g a iront view of the retractor blade of figure 4. Figure 8 shows with corresponding numbering an enlarged but abbreviated side elevation view of the distal end of the blade of figure 4.

[0046] Figure 9 shows a perspective view of a retractor blade according to an alternative embodiment. Retractor blade 50 is largely the same as retractor blade 30 and comprises a generally elongated: ^' but arcuate blade body 51 having proximal free end 52 and distal working end 53. Proximal end 52 either provides means for connection to a suppor ( not shown) or is simply adapted for many a 1 operation. Distal end 53 comprises a first part 54 oriented in a first direction and a second part 55 integral with the first part and forming a radiused curve which is intended to accommodate contours of patient anatomy. Third part 56 is flattene out and is disposed at 90 degrees to the first part 54, His geometry is illustrative and is not to be taken as limiting of the various geometries which may be selected to accommodate patient anatomies. The first part 53 terminates in an edge 57 and at or adjacent to edge 57 along a least part of edge 57 is a hook formation 58 which includes a female recess 59 which receives and retains therein an. anchor pin ( see figure 3). Formation 38 is shown integrall connected to an opposite side of part of edge 57. [0047] Thus a retractor blade having the hook formation 38 on retractor 30 is a side by side mirror image of the hook formation 58 of the retractor blade 50, This opposite geometry of each formation allows two retracto blades to work side by side and move in opposite direction (awa from each other) during distraction of spinal vertebra. Distraction force are transmi tted via anchor pins to th retractor blades causing the blades to -move apart ensuring a clear" field of view and access for the surgeon. Alternatively, opposing blades may operate an opposite side of st wound

[0048] Edge 57 is when blade 50 is in rise., disposed in an orientatio which is essentially parallel to a longitudinal axis of a spine ^■■■■ see figure 1 below. The formation 5.8 is eanti levered from first part 53 and may be configured to suit a particular geometr according to the relationship between the edge 57 of blade

50 and the angulation required to enable formation 58 to engage an anchor pin, For example the angle of repose betwee the formation 58 and the blade body

51 may be an acute or obtuse angle or normal to the ^' first part 53 of blade 50. The angle of repose of formation 58 relative to the plane of first part 53 dictates the approach angle to the anchor pins. Such angles are best shown in schematic fi ure 14a below.

[0049] Figure 10 shows a plan view of the retractor blade of figure 9. Figure 11 shows an enlarged view of circled area A of figure 10 comprising the distal end formation according to a preferred embodiment

[0050] Figure 12 shows a cross sectional elevation through a spine 60 having pins 61 and 62 connected in separate vertebra 63 and 64 ( obscured) and opposing retractors 65 and 66. Retractor 65 engages pin 62 via formation 67. Angled retractor 65 has a different profile from curved retractor 66 to accommodate different anatomy. Retractor 66 engages pin 61 via formation.68. It will be appreciated that the side profile of the retractor can be adjusted as required for particular anatomy. Figure 13 shows with corresponding numbering a plan view of the arrangement of figure 12.

[0051] From this view its can be seen that formation 67 engages pin 62 and foraratton 68 engages pin 61. Retractor blade 65 has a long axis 72 and a short transverse axis 7L Likewise retractor 66 has a long axis 70 and transverse axis 69Pms 61 and 62 apl distraction forces in the directions of arrows 75 and 76. This -allows access to disc space 77. As pins 61 and 62 distract, retractor blades 65 and 66 can displace along with the pins. Figure 13 shows one possible geometry for each formation 67 and 68. It will be appreciated that the geometry may be changed and the shape of the formation may also change from that depleted as long as the formations allow the retractors to move with the anchor pins 61 and 62.

[0052] Figure 14 a,b,c show a schematic view o various angulations which may be applied to retractors described herein to accommodate various anatomical .structures. Figure 14 a is a view through body looking from the head end to the foot end and shows a retractor SO adjacent the left carotid artery 81 and engaging at its distal end 82 a spinal bone 83. Retractor 84 has an alternative shape and in this case abuts the trachea 85 and Oesophagus 86. Eac end of the retractor blades 80 and 84 engages respective pins which are not shown inserted into spine 83. Figure 14b shows retractor 84 isolated from its in situ position show in figure 14a.

[0053] Angulation is to minimize the retraction and to optimize the vision for a surgeon which on one side is less than 90 degrees and on the other side more than 90 degrees currently one side 85 degrees and other side 140 degrees. Preferably the range is between 20-170 degrees. In figure 1.4c Part A and part B are .identified. Pan .8.length depends on the depth of th field. The curve at the end is to facilitate handling. The width of the part B is to optimise the width, of the operating field. Expose the disc space and min mize the force to rotate the retractor (the wider the -retractor the higher the force by esophagus muscles to rotate the retractor around the pin the range of part B is around 5- 50 mil! wide .

[0054] Part A length should minimize the retraction optimize the width of the disc exposure enough for discectomy and disc replacement ( cages, artificial discs) the range of part A is 5 - 30 mm; there is a potential to be used for other spinal levels like thoracic, lumbar, other animals). Part A may be attached to part B at different paints longitudinally (0-5Qram). Part A may be curved or s traight wi th the width of part A configured to fit an anchor pip, provide enough strength and- maximize the operating field. Part: A maybe inverted (opening inside rather than outside and should be on the either end to -ma mize the useable width of the retractor. j _. 0055] Various materials may be used for the retracto including metals and plastics and malleable and radiolucent materials. Various sizes and shapes and configurations of a distal end are envisaged which are each able to engage an

1.8 anchor pi so that the retractor is able to move longtftidinali relative to spinal axis >

[0056] Variations in the retractor may be made to accommodate different variation in engagement to vertebrae. For instance the length, widt and relative heights of horizontal and vertical sections, may var to accommodate, different locations in the spine and different types of procedures.

[0057] ft will be further recognised by persons skilled in. the art that numerous variations- and modifications may be made to the invention without departing from the overall spirit and scope of the invention broadly described herein. Such modifications would allow adaptation of key concepts to provide locking of distraction devices for use in anterior or posterior spinal surgery throughout the length of a spine or in orthopaedics or other surgical disciplines where bony fixatio is available.