Abstract:
An apparatus includes a distractor assembly adapted to couple to a leg and capable of providing a distraction load on the leg in both supine and lateral positions of the leg. The assembly is coupled to a surgical table by a ball joint or a universal joint. A method includes coupling a leg to a distractor assembly, positioning the leg in one of a distraction mode and a femoral acetabular impingement mode, and repositioning the leg in the other of the modes without the need for accessing a draped pelvis/thigh region.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to hip distraction.  
       BACKGROUND  
       [0002]     To gain access to the hip joint to perform hip arthroscopy, the femoral head (ball) is pulled out of the acetabulum (socket) in the pelvis. Hospitals typically use a fracture table to put the hip joint under traction while the patient is in a supine position. Hip distractors are known that attach to a standard operating table, and that are dedicated to use with the patient in either a supine position or a lateral position.  
         [0003]     Two methods for hip distraction are Distraction Mode, in which the lower extremity is put in tension via traction between the foot and pelvis, and Femoral Acetabular Impingement (FAI) Mode, in which there is no traction on the lower extremity and there is a larger range of motion than the distraction mode. In the FAI Mode, the hip is flexed up between 30 to 90 degrees and the knee is flexed approximately 45 degrees. The scrub nurse holds the knee from falling laterally. Both methods can be performed using a fracture table with the patient in the supine position. To move a patient between the two modes, and to move the hip joint through its range of motion to check for impingement between the femoral neck and the acetabular rim, the circulator nurse reaches under the draped foot area to unlock the table.  
       SUMMARY  
       [0004]     According to one aspect, an apparatus includes a distractor assembly adapted to couple to a leg and capable of providing a distraction load on the leg in both supine and lateral positions of the leg.  
         [0005]     Embodiments of this aspect may include one or more of the following features. The distractor assembly includes a joint, for example, a ball joint or universal joint, configured to couple the distractor assembly to a surgical table. The joint is lockable and the mechanism for locking the joint is located remote from the joint. The apparatus is configured such that with a patient positioned on the surgical table and coupled to the distractor, the joint is offset from the patient&#39;s hip joint. The apparatus is entirely supported by a surgical table.  
         [0006]     In an illustrated embodiment, the distractor assembly includes a distractor member and a leg mount, for example, a foot mount, coupled to the distractor member for movement relative to the distractor member by both sliding and threaded engagement. The leg mount is coupled to the distractor member by a ball joint. The apparatus includes a foot holder mountable to the distractor assembly and including a support bar that supports the lower leg in the lateral and supine positions.  
         [0007]     The apparatus further includes a support configured to be fastened to a surgical table, and the distractor assembly includes a joint, for example, a ball joint or a universal joint, coupling the assembly to the support. The support includes two mounts for coupling to the joint and the distractor assembly is arranged for use with a patient in a supine position with the joint coupled to a first of the mounts for surgery on a right leg, or to a second of the mounts for surgery on the left leg.  
         [0008]     According to another aspect, a method includes coupling a leg to a distractor assembly, positioning the leg in one of a distraction mode and a femoral acetabular impingement mode, and repositioning the leg in the other of the modes without the need for accessing a draped pelvis/thigh region.  
         [0009]     According to another aspect, an apparatus includes a distractor member configured for coupling to patient table, and a leg mount coupled to the distractor for movement relative to the table by both sliding and threaded engagement.  
         [0010]     According to another aspect, an apparatus includes a distractor member configured for coupling to patient table, a ball joint, and a leg mount coupled to the distractor member by the ball joint. The apparatus is configured such that relative movement between the foot mount and the table applies a distraction load to a patient. Embodiments of this aspect may include that the apparatus is configured to be entirely supported by a surgical table.  
         [0011]     According to another aspect, an apparatus includes a distractor assembly configured to apply a distraction load to a patient including a ball joint or a universal joint for coupling the assembly to a surgical table.  
         [0012]     Embodiments of this aspect may include that the joint is lockable, and that the apparatus is configured such that with a patient positioned on the surgical table and coupled to the distractor assembly, the joint is offset from the patient&#39;s hip joint.  
         [0013]     According to another aspect, an apparatus includes a foot holder for use during surgery having a support bar configured and arranged to support a patient&#39;s lower leg.  
         [0014]     According to another aspect, an apparatus includes a distractor member, a support configured to be fastened to a surgical table, and a joint coupling the distractor member to the support. The support includes at least two mounts for coupling to the joint.  
         [0015]     According to another aspect, a method includes coupling a distractor member to a patient&#39;s leg, and dislocating the patient&#39;s hip by applying an adduction force to the patient&#39;s leg.  
         [0016]     According to another aspect, a method includes coupling a distractor member to a patient&#39;s leg, and applying a distraction force with the distractor member to the patient&#39;s leg through a bent knee.  
         [0017]     According to another aspect, an apparatus includes means for providing a distraction load on a leg in both supine and lateral positions of the leg.  
         [0018]     According to another aspect, an apparatus includes means for repositioning a leg between a distraction mode and a femoral acetabular impingement mode without the need for accessing a draped pelvis/thigh region.  
         [0019]     Advantages of the apparatus and method may include ease of positioning throughout the large range of motion required in FAI Mode, ease of repositioning between Distraction and FAI Modes, a single system that allows for both supine and lateral positioning, freeing the scrub nurse from holding the knee from falling laterally in FAI Mode, and less expensive than a fracture table.  
         [0020]     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0021]      FIG. 1  illustrates a distraction assembly arranged for use in a Distraction Mode with the patient in a supine position.  
         [0022]      FIG. 2  illustrates the distraction assembly arranged for use in a Distraction Mode with the patient in a lateral position.  
         [0023]      FIG. 3  illustrates the distraction assembly arranged for use in a FAI Mode with the patient in a supine position.  
         [0024]      FIG. 4  illustrates the distraction assembly arranged for use in a FAI Mode with the patient in a lateral position.  
         [0025]      FIG. 5  is an isometric view of the distraction assembly and a foot holder attached to the distraction assembly.  
         [0026]      FIG. 6  is an isometric view of a ball joint of the distraction assembly.  
         [0027]      FIG. 7  is an isometric view of a slider and foot mount of the distraction assembly.  
         [0028]      FIG. 8  shows the foot holder attached to the slider.  
         [0029]      FIG. 9  is an illustration of a boot of the foot holder.  
         [0030]      FIGS. 10A and 10B  are isometric views of a table extension for mounting the distraction assembly to an operating room table with the patient in a supine position.  
         [0031]      FIG. 11  is a top view of the distraction assembly also illustrating a non-operative leg holder for the supine position.  
         [0032]      FIG. 12  is an isometric view of a lateral positioning table extension and pad.  
         [0033]      FIG. 13  is a top view of the distraction assembly arranged for lateral positioning.  
         [0034]      FIG. 14  illustrates an alternative embodiment of a hip distractor.  
         [0035]      FIG. 15  illustrates another alternative embodiment of a hip distractor. 
     
    
     DETAILED DESCRIPTION  
       [0036]     Hip distraction is performed in either the Distraction Mode ( FIGS. 1 and 2 ) or Femoral Acetabular Impingement (FAI) Mode ( FIGS. 3 and 4 ) using a system  10  that can be attached to a standard operating table  12 , such as found in hospitals and surgery centers, and that can accommodate both supine ( FIGS. 1 and 3 ) and lateral ( FIGS. 2 and 4 ) positioning of the patient. The system permits operating room personnel to reposition the patient between Distraction Mode and FAI Mode without needing to access the draped pelvis/thigh region.  
         [0037]     Referring to  FIG. 5 , a distractor assembly  100  includes a distraction member, for example, a longitudinal spar  102  having a D-shaped cross-section, a lockable ball joint  104  (available from Allen Medical of Acton, Mass. and as seen in Allen Medical&#39;s Ultrafin stirrup products) attached to the proximal (pelvis) end  106  of the spar, a coupler  108  attached to the ball joint  104  for coupling the distractor assembly  100  to an operating room table, a slider  110  slidably mounted on the spar  102 , and a leg mount, for example, foot mount  112 , attached to slider  110  via a lockable ball joint  114  and a rigid, stationary arm  116 . The ball joint  104  can be locked and unlocked by actuating a knob  118  located at the distal (foot) end  120  of the spar  102 , thus allowing for the assembly to be unlocked and repositioned without need to access the draped pelvis/thigh region.  
         [0038]     The ball joint  104  and the coupler  108 , as shown in  FIG. 6 , allows for a large range of hip motion, providing a full range of motion about the horizontal axis, and about 80 degrees of motion in the horizontal plane. The coupler  108  includes a yoke  130  that receives horizontally extending side arms  132  of the ball joint  104 .  
         [0039]     Referring to  FIGS. 5 and 7 , the slider  110  defines a D-shaped longitudinal through bore  150  that slidably and non-rotationally receives the spar  102 , and a threaded, lateral through bore  152  that receives a locking bolt (not shown), that is tightened to lock the slider  110  to the spar  102 . The slider  110  includes handles  154   a,    154   b  that are used by the operating room personnel to slide the slider relative to the spar to provide gross distraction of the leg. For fine distraction, the slider  110  includes a base  156  supporting a threaded rod  158  attached to a turn handle  160 . The base  156  also slidably supports a yoke  162  defining a threaded bore  164  through which the threaded rod  158  is received. By turning the handle  160 , the yoke  162 , and therefore the foot mount  112  attached to the yoke by the ball joint  114  and arm  116 , can be moved back and forth relative to the base  156  to apply a desired amount of traction, for example, 25-150 pounds of force, to the leg.  
         [0040]     Attached to the foot mount  112  of the assembly  100  is a foot holder  122  ( FIGS. 5 and 8 ). The foot holder  122  includes a boot  180 , a shin support  182 , and a support bar  184  that holds the upper tibia aligned with the foot. The support bar is particularly advantageous during FAI to stabilize the knee from falling laterally thus freeing the scrub nurse from having to hold the patient&#39;s leg in position. Referring also to  FIG. 9 , boot  180  includes a foot housing  186  with a tightening clasp  188 , a sole  190 , a U-coupling  192  that receives the foot mount  112 , and straps  194  for securing the boot to the foot mount. The foot housing  186  has three straps, not shown, that go over the patient&#39;s forefoot and close the foot housing onto the foot.  
         [0041]     The support bar  184  has two legs  202   a,    202   b,  the ends of which are respectively received within openings  204   a,    204   b  of foot mount couplers  206   a,    206   b  ( FIG. 7 ). The shin support  182  is attached to support bar  184  via shin mounts  208 . The ball joint  114  and arm  116  permit the patient&#39;s leg to be finely positioned.  
         [0042]     To support the patient&#39;s buttocks when the patient is in a supine position and to attach the distractor assembly  100  to the operating room table, a table extension  220  ( FIGS. 1 and 10 A) is employed. The table extension  220  includes a frame  222  with a cross bar  224 , an angled strut  226 , a Y-yoke  228 , a vertical strut  230 , and a platform  232 . Extending from the cross bar  224  are two arms  234   a,    234   b  that are used to attach the table extension to the operating room table  12  using rail clamps  14 . The coupler  108  of the distractor assembly  100  plugs into one of a pair of female sockets  236   a,    236   b  defined in Y-yoke  228  and is secured in place by a threaded locking knob (not shown). Since the ball joint  104  does not provide a large enough range of motion in the horizontal plane to accommodate surgery on both the right and left hips, socket  236   a  is used for surgery on the right hip, and socket  236   b  is used for surgery on the left hip, with the ball joint  104  providing the additional range of motion in the horizontal plane required for fine position of the leg.  
         [0043]     The platform  232  is x-ray translucent and defines through holes  240   a,    240   b  for receiving a post  242  ( FIG. 1 ). The post  242  is received over a respective plug  244   a,    244   b  of Y-yoke  228 , and a peroneal pad  244  ( FIG. 1 ) slips over the post  242 . The post and pad provide the restraining force against the pelvis when the distraction force is applied to the leg. Through hole  240   a  is used for surgery on the right hip, and through hole  240   b  is used for surgery on the left hip. As shown in  FIG. 10B , a pad  246  is attached to the platform  232 . The pad defines a cut-out  248  permitting access to holes  240   a,    240   b.    
         [0044]     Referring to  FIGS. 10A and 11 , a non-operative leg holder assembly  260  is secured within the respective opposite socket  236   a,    236   b  from that in which distractor assembly  100  is secured. Assembly  260  includes a spar  262  to which a foot mount  264  is slidably attached via a lockable slider  266  ( FIG. 1 ). Attached to foot mount  264  is a boot  268  through which mild traction, for example, about 20 pounds can be applied to the non-operative leg.  
         [0045]     To position the patient in the supine position for the Distraction Mode ( FIG. 1 ), operating room personnel lower the operating room table&#39;s foot section  16  to the vertical position, clamp the table extension  220  to the side rails  18  of the table, and connect the distractor assembly  100  and leg holder  260  to the table extension. A patient transfer board (not shown) can be attached to the table extension to provide interim support to the legs while the feet are strapped into the boots  180 ,  268 .  
         [0046]     The operating room personnel then place the patient on the table, anaesthetize the patient, and attach the peroneal post and pad to the table extension. The patient is then brought down the table firmly against the peroneal pad, and the feet are wrapped in disposable foam booties (not shown) and strapped into the boots. The well leg is put under mild traction and the foot allowed to pivot into it&#39;s neutral position. The operating room personnel remove the patient transfer board and put the operative leg under initial traction by sliding the carriage  110  along the spar  102  until mild traction, for example, about 20 to 50 pounds, is achieved. The sliding carriage is then clamped to the spar. Further traction is achieved via the mechanical advantage of the threaded screw  158  between the carriage and boot. This distracts the hip via traction through the ankle and knee joints. The foot can be locked in any orientation (flexion or rotation) via the ball joint  114  between the boot and the threaded screw.  
         [0047]     The surgeon then checks the distraction with fluoroscopy, places a drape over the patient, including covering the pelvis/thigh region of the patient, and places portals through the patient&#39;s skin leading to the hip joint under fluoroscopy control. As soon as the first portal is created the vacuum seal between the femoral head and acetabulum is broken and the joint distracts further. This can be aided by injecting fluid into the joint.  
         [0048]     To move the patient from Distraction Mode to FAI Mode ( FIG. 3 ), the operating room personnel reduce the traction force by turning the threaded screw  158  until no force is on the joint, unlock the ball joint  104 , and lift the femur into flexion by raising the spar  102 . Since the center of rotation of the spar, i.e., the ball joint  104 , is located below the hip joint of the patient, the knee flexes as the spar is raised. The natural tendency of the knee to fall laterally is limited by the boot&#39;s lateral support bar  202   a,    202   b  thus freeing the scrub nurse to help the surgeon.  
         [0049]     Referring to  FIGS. 12 and 13 , for lateral positioning of the patient, the system  10  includes a “U” shaped peroneal bar  280  supporting a pad  282 . The bar  280  has a socket  284  for receiving the coupler  108  ( FIG. 5 ) of the distractor assembly  100 , and the pad  282  defines a cut-out  286  for accessing socket  284 . Bar  280  is attached to the side rails  18  of the operating room table  12  using clamps  14 .  
         [0050]     To position the patient in the lateral position for the Distraction Mode ( FIG. 2 ), with the operating room table&#39;s foot section  16  up, the anaesthetized patient is rolled onto their side, the operating room personnel clamp the bar  280  to the side rails  18  with the pad  282  positioned between the patient&#39;s legs. To obtain lateral distraction, the operating room personnel raise the bar  280  by rotating the bar within the clamps  14  and lock the clamps. The distractor assembly  100  is then attached to the bar  280  and the operative leg wrapped in a disposable foam bootie (not shown) and strapped into the boot. As discussed above, gross distraction is achieved by moving the carriage  110  followed by fine distraction using the threaded screw  158 . The boot can be positioned in any combination of flexion or rotation. There is no need for a non-operative leg holder as the non-operative leg is supported by the table&#39;s foot section  16 .  
         [0051]     To move between the Distraction Mode ( FIG. 2 ) and FAI Mode ( FIG. 4 ), the spar  102  is pivoted laterally about the ball joint  104 . Since the center of rotation of the spar  102 , i.e., the ball joint  104 , is located distal to the hip joint of the patient, the knee flexes as the spar is moved laterally. The natural tendency of the knee to fall towards the floor is limited by the boot&#39;s lateral support bar  202   a,    202   b,  thus freeing the scrub nurse to help the surgeon.  
         [0052]     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, the distractor assembly can include a tensiometer to provide the surgeon with the distraction force. The slide and spar can be other than D-shaped, though preferably the slide and spar are configured such that the slide can slide along the spar without rotating. The ball joint  104  can be replaced with a two axis universal joint  104   a  ( FIG. 13 ). Rather than locating screw thread  158  at slider  110 , fine adjustment can be provided by a screw thread located, for example, between the ball  104  and the spar  102 .  
         [0053]     In an alternative configuration shown in  FIG. 14 , hip distraction is achieved via a pivoting action. Rather than using only axial force to dislocate the hip joint, a lever that pivots along the thigh translate a small foot adduction (movement towards the body centerline) into a large lateral hip distraction force. With a pivot  301  closer to the hip joint than to the foot end of a spar  310 , a simple lever is created. The operative foot is held to the spar  310  by a boot assembly  320 . Thus, when a small adduction force F 1  is applied to the spar  310  near the foot region, the mechanical advantage provided by the lever creates a larger lateral force at the hip joint. A peroneal pad  344  pushes laterally against the upper femur moving the femoral head of the hip joint. In addition to this lateral force, an axial force F 2  is imparted on the hip joint via traction through the boot assembly  320 . This force can be achieved though turning of a crank  360  which is rotationally connected to a threaded rod  380 . The boot assembly  320  is threaded to rod  380  but is limited from rotating by spar  310 , thus boot assembly  320  moves axially when the crank  360  is turned. The peroneal pad  344  also provides a reaction force against the pelvis.  
         [0054]     Referring to  FIG. 15 , distraction can be achieved through a bent knee providing a more compact distractor. With the operative leg bent approximately 90 degrees at the knee, the distraction force can be exerted at the knee. In addition, the reactive force that is borne through the non-operative leg can be reacted at the knee rather than through the ankle. Bent knee distraction of the operative leg is carried out by transmitting a distraction force to the upper tibia via a strap  430 . The distraction force is transmitted through the knee to the femoral head. A peroneal pad  444  is connected to the surgical table and reacts the distraction force by pushing against the pelvis. A telescoping spar assembly  400  includes a bar  420 , which is connected to a tube  410  by a slidable, lockable mechanism, such as a one-way ratchetting pawl.  
         [0055]     When distraction is pulled on the operative leg, the pelvis tends to rotate around a vertical axis “Z” created by the peroneal pad. In order to minimize this pelvic rotation, a bent knee counter traction force is imparted upon the non-operative leg by a support  440 . This force can be transmitted to the upper tibia via surface  450  which is then transmitted through the knee to the femoral head and pelvis. The support  440  can be fixed to the surgical table or it can telescope like spar assembly  400 . If support  440  is fixed then the patient is moved proximally to create the counter traction force.  
         [0056]     Accordingly, other embodiments are within the scope of the following claims.