Abstract: A load gauge to measure the forces that must be applied to properly position a spinal fixation assembly to one or more vertebrae. In a preferred embodiment, said load gauge is attached to a bone screw. The bone screw is in turn connected to a rod through a connector. After the bone screw is inserted into a vertebrae, the load gauge measures the force that must be applied to properly position the spinal fixation assembly vis-a-vis the vertebrae. The present invention allows surgeons to have more flexibility on how and how much the deformed spine is corrected.

Abstract: An instrument includes a flexible shaft portion and a hook portion. The flexible shaft portion has a proximal end and a distal end and includes markings along an outer surface of the shaft portion. The hook portion is located at the distal end of the shaft portion. The shaft portion and the hook portion define a lumen that terminates in an opening at the hook portion.

Abstract: In a method for determining the angle of anteversion and/or the angle of inclination of an acetabulum in a pelvic bone, in order to achieve a simplification, a method is proposed, wherein prominent points on the pelvic bone are non-invasively determined, these prominent points are joined by an individual plane, and this individual plane is respectively rotated through predetermined, specific angular magnitudes for the angle of inclination and the angle of anteversion, respectively, and the angle between the rotated individual plane and a main plane of the pelvic bone is determined in order to determine the angle of inclination and the angle of anteversion.

Abstract: The present teachings provide one or more surgical instruments for repairing damaged tissue, such as in the case of a hip or femoral fracture. The present teachings can also provide one or more orthopedic screws that can be inserted in and/or removed from bone using any of a dedicated driver or any of commonly available drivers. The present teachings can further provide a surgical instrument that includes dual reconstructive wires and associated method, among other instruments and methods for repairing a hip or femoral fracture.

Abstract: Methods and apparatus for aligning two or more longitudinally space parts of a body, such as leg bones, prior to and/or during a surgical procedure using a laser light guide assembly are described. The apparatus may have a saddle for attachment to a specific body part, and comprises a first horizontally rotatable structural member pivotably secured to the saddle or other support means, and a second rotatable structural member aligned vertically and perpendicular to the first structural member. A laser light guide which includes a laser is attached to the second structural member, the laser capable of generating a laser light beam of sufficient strength and intensity to allow for alignment of the body parts prior to and during a surgical procedure.

Abstract: A method of assembling an orthopaedic implant includes positioning a first orthopaedic component in contact with a second orthopaedic component and coupling the first orthopaedic component to the second orthopaedic component with a bolt. The method also includes applying an empirically-determined starting torque to the bolt such that the first orthopaedic component is coupled to the second orthopaedic component with a first predetermined clamp load. The bolt is then rotated by an empirically-determined rotation angle such that the first orthopaedic component is coupled to the second orthopaedic component with a second predetermined clamp load.

Abstract: The present disclosure is directed to orthopedic implants and methods of designing orthopedic implants using in vivo data specific to an orthopedic implant or orthopedic trial. Specifically, the instant disclosure utilizes permanent orthopedic implants and orthopedic trials outfitted with pressure sensors to provide feedback regarding the position and magnitude of pressures exerted upon the devices to discern which design is preferable or which designs are preferable.

Abstract: Positioning instruments and related methods are described for implanting an energy absorbing system for treating joints. The positioning instruments and methods allow the energy absorbing system to be positioned at a joint such that the desired motion will occur for the particular design of a particular energy absorbing system which is to be implanted. The positioning instruments include a locating instrument for locating an anatomical feature and a target location for implantation of the energy absorbing system, a verification instrument for verification of the target location, a placement guide for guiding placement of a part of the energy absorbing system, and positioning device for aligning portions of the energy absorbing system.

Abstract: A feeler gauge and alignment device comprises a first outer shim having a first end, a second end, and an alignment aperture disposed between the first end and the second end, a second outer shim having a first end, a second end, and an alignment aperture disposed between the first end and the second end, and one or more inner shims disposed between the first outer shim and the second outer shim, each of the one or more inner shims having a first end, a second end, and an alignment aperture disposed between the first end and the second end. The first outer shim, the second outer shim, and the one or more inner shims are rotatably coupled about the first ends.

Abstract: A trial head and shell for use in trial reduction of hip implants, and particularly bipolar implants, having locking features that prevent the head from dissociating from the shell during trialing, yet which allow the head and shell to be readily assembled and disassembled in the operating room. A cut-out region is formed in an outer bearing surface of the head. The cut-out region allows the head to pass through a trial shell opening and into the shell, yet is oriented such that when the head is associated with a femoral neck, the head cannot disassociate from the shell. Orientation indicators can be provided for use in assembly and disassembly. The trial head and associated shells can be provided in the form of a surgical kit including hip implants. Methods of use are provided.

Abstract: A device and methods for use in determining the trajectory of a patella of a patient during a navigated knee replacement surgical procedure are described. The device includes a first component including a mounting for attachment to a posterior surface of the patient's patella and a second component having an outer surface presenting a formation adapted to engage with a femoral part of the patient's knee. A slider mechanism allows the second component to translate relative to the first component in a substantially medial-lateral direction of the patient when the first component is attached to the patient's patella. The device can be used in a method to help determine the medial-lateral position for a patella implant.

Abstract: Disclosed herein are tools for repairing articular surfaces repair materials and for repairing an articular surface. The surgical tools are designed to be customizable or highly selectable by patient to increase the speed, accuracy and simplicity of performing total or partial arthroplasty.

Abstract: An AMZ tibial tuberosity transfer system and method of treatment of patellofemoral joints. The AMZ system includes 1) a retractor with a better conformation to anatomy and more curve (not just a bend), and also with a larger radius on the front of the retractor to allow for easier insertion; 2) a cutting block that can fully accept a collared pin; 3) a rod preferably formed of stainless steel; 4) a tuberosity pin guide; 5) an exit indicator that engages tightly the cutting block so there is no slope on exit indication; and 6) a horizontal bar provided with markings to measure the medial shift.

Abstract: An instrument assembly for placing a guide pin in a femoral neck of a patient with reference to a medullary guide wire for use in resurfacing a femoral head. The assembly comprises a femoral neck clamp configured to define a femoral neck center. A pin guide attaches to the femoral neck clamp. A pin guide portion of the pin guide is configured to define a pin guide path passing through the neck center. The pin guide portion is linked to pin guide engagement portion of an adjustable goniometer. The goniometer maintains a specific angle between the pin guide engagement portion and the medullary guide wire, and in turn maintains the pin guide path at the specific angle.

Abstract: A depth gauge and method provide for accurate measurement of a socket portion of a bone tunnel in an ACL reconstruction.

Abstract: A surgical instrument for implanting a prosthetic member. The instrument includes an orientation sensor that detects an initial orientation of the prosthetic member and an implanting orientation of the prosthetic member. The instrument further includes a memory module and an input device that receives a user input to transfer the initial orientation detected by the orientation sensor into the memory module for storage. Furthermore, the instrument includes an orientation feedback device that selectively provides an orientation feedback signal to a user. Moreover, the instrument includes a controller that causes the orientation feedback device to provide the orientation feedback signal when the implanting orientation detected by the orientation sensor is substantially equal to the initial orientation stored in the memory module.

Abstract: A sensor system uses positive closed-loop feedback to provide energy waves into a medium. It comprises a transducer (604), a propagating structure (602), and a transducer (606). A parameter is applied to the propagating structure that affects the medium. A sensor is coupled to a propagation tuned oscillator (416) that forms a positive closed-loop feedback path. The propagation tuned oscillator (416) includes a zero-crossing receiver (200) that generates a pulse upon sensing a transition of an energy wave from the propagating structure (602). The zero-crossing receiver (200) is in the feedback path that maintains the emission of energy waves into the propagating structure (602). The zero-crossing receiver (200) comprises a preamplifier (206), a filter (208), an offset adjustment circuit (210), a comparator (212) and a pulse circuit (218). The transit time, phase, or frequency is measured of the propagating energy waves and correlated to the parameter being measured.

Abstract: Disclosed herein are methods and compositions for producing articular repair materials and for repairing an articular surface. In particular, methods for providing articular repair systems. Also provided are articular surface repair systems designed to replace a selected area cartilage, for example, and surgical tools for repairing articular surfaces.

Abstract: An instrument for recording and replicating the spatial orientation of a dialable component of an implant relative to a bone engaging component of the implant includes a base assembly configured to support the trial implant so that the datum is in a predetermined orientation, a fixture supported on said base assembly, said fixture including an alignment tool configured to engage the first dialable component of the trial implant when the trial implant is supported by said base assembly, and a locking assembly configured to record the angular orientation of said alignment tool relative to said fixture with said alignment tool engaged with the first dialable component, and to replicate the recorded angular orientation with the alignment tool and a second dialable component.

Abstract: A femoral gauge for sizing a femoral head implant and locating osteophytes or structural abnormalities comprising a gauge portion, the gauge portion having a concave gauge surface and an opposing back surface, the gauge surface defined by a pair of opposing lengthwise sides and a pair of widthwise sides, the gauge surface having a substantially spherical contour, the spherical contour sized for selection of a correspondingly sized femoral head implant, and a handle portion extending from the gauge portion, the handle portion positioned and configured for use in positioning the gauge surface. A plurality of different sized gauges can be provided. Areas of potential infringement can be located by rotating the femoral gauge around the juncture of the natural or implant femoral head and the natural femoral neck. Areas of impingement are removed until the femoral gauge can be rotated around the juncture without lifting off of the femoral head.

Abstract: A lock indicator gauge is provided to provide an indication as to whether a bone screw construct is in a locked or an unlocked condition when the lock indicator gauge is operatively engaged with the bone screw construct. A plunger longitudinally disposed within a housing of the lock indicator gauge translates within the housing by a distance that corresponds to the relative positions of inner and outer housings of the bone screw construct, wherein the relative positions of the inner and outer housings is dependent on whether the bone screw construct is in a locked or an unlocked condition.

Abstract: The invention relates to a device for determining the mechanical leg axis of a femur. Said device is provided with a shaft (3) that comprises, on one of its ends, a securing device (5) that is connected to the shaft and that can be blocked at various angles, in order to obtain a fastening that can be blocked in an angle stable manner and that fastens the shaft (3) to the knee joint of a femur, and comprises a gripping element (10) on its other end. A force-torque measuring device (14) is arranged between the gripping element (10) and the shaft (3), said device enabling the longitudinal and/or transversal force components of force (Fz) exerted via the shaft (3) upon the knee joint to be measured by means of the gripping element (10) and/or torque produced thereby. The invention also relates to a method for determining the mechanical leg axis of a femur by means of the above mentioned device.

Abstract: A universal targeting apparatus includes a generally U-shaped body having one end configured to be coupled to the proximal end of the intramedullary implant and a mounting portion at an opposite end of said body. An arm is rotatably mounted to the mounting portion of the U-shaped body and includes bores defined at its opposite ends. Each bore is arranged at a different angle to correspond to the angle of a transverse aperture in the intramedullary implant. The arm can be rotated so an appropriate one of the angled bores is aligned with the transverse aperture to serve as a guide for creating targeting holes in the bone.

Abstract: An implant comprising a first, second, and third segment wherein the second and third segments partially overlap the first segment and define a load bearing surface comprising an anterior-posterior (AP) curvature including at least two tangential curves of the portion of the articular surface of the femoral condyle, the tangential curves having different radii of curvature. A drill guide comprises a body portion including a first, second and third bushing spaced along the body portion to establish a first, second and third axes, respectively. Each axis may be substantially normal to the articular surface at three different points along a curvature of the articular surface comprising the two tangential curves. A measuring device comprises a housing defining a longitudinally passageway and an outrigger. A guide pin may be received in the longitudinal passageway and a measuring device determines how far the guide pin is in the passageway.

Abstract: Apparatus and methods for measuring spacing between first and second bone screws engaged with first and second bone structures are provided. An apparatus comprises first and second arms operably engaged with a single pivot pin. The first arm includes a distal end adapted to engage the first bone screw, and a proximal end comprising a graduated scale. The second arm, operably engaged with the first arm via the single pivot pin, includes a distal end adapted to engage the second bone screw, and a proximal end comprising an indicator segment slidably engaged with the graduated scale. A position of the indicator segment relative to the graduated scale is therefore indicative of a spacing between the first and second bone screws.

Abstract: A surgical instrument and instrumentation are suggested, with which expansion of the vertebral canal of vertebrae is possible with less stress for the patient than with operating procedures customary up to now, this instrument having proximally a gripping part and distally two branches which can be moved relative to one another with tool elements held thereon as well as a lever mechanism arranged between the gripping part and the branches, wherein the tool elements are held with the lever mechanism so as to be movable relative to one another from a closed rest position into an open spread position (distraction position).

Abstract: The invention is a surgical instrument for measuring an intervertebral space. On the distal end of a handle of the instrument there are at least two measurement plates, whereby an interval between the measurement plates, and an angle enclosed by the measurement plates, are adjustable.

Abstract: Advances in our understanding of the cellular mechanisms underlying skeletal regeneration have not been effectively translated in vivo treatment because non-invasive monitoring of bone fracture healing is limited to imaging technology (i.e., for example, x-rays) that cannot be quantified and are subjectively interpreted. The method disclosed herein assesses rates of hip fracture healing using a strain gauge device implanted into a standard orthopedic implant. It has been demonstrated that such a device can measure differences between intact and partially osteotomized fracture models (p<0.05) and that the device can distinguish between stable and unstable fracture patterns in completely osteotomized models across a physiologic range of loads. Such devices are compatible with in vivo bone fracture healing methods, wherein the device is placed onto an orthopedic implant and the strain data is transmitted on a real time basis, thereby providing a non-invasive quantification of bone fracture repair rates.

Abstract: A method of determining the pedicle base circumference and the pedicle isthmus to facilitate screw placement in a pedicle of a vertebral body during spinal surgery, comprising providing a series of first lines tangential to the outer cortical surface of the vertebral body in and near the pedicle on a transverse section from a three-dimensional image of the vertebral body, providing a series of second lines extending through the vertebral body in and near the pedicle thereof in perpendicular relation to the series of first lines, identifying the pedicle base circumference as the areas of the outer cortical surface where adjacent second lines are at the greatest angle with respect to one another, and identifying the pedicle isthmus as the areas of the outer cortical surface where the second lines that are opposed to each other are closest to being parallel to one another.

Abstract: An instrument for recording and replicating the spatial orientation of a dialable component of an implant relative to a bone engaging component of the implant includes a base assembly for supporting the bone engaging component and a fixture supported on the base assembly for supporting an alignment tool. The alignment tool is configured to engage a portion of the dialable component when the implant is supported by the base assembly. The fixture includes a locking assembly for locking the spatial position of the alignment tool relative to a pre-determined datum on a trial implant. The same instrument can be used to support a final implant and to replicate the spatial position of the alignment tool relative to the same datum on the final implant. The alignment tool can then be used to align the dialable component of the implant. The alignment tool can also constitute an impacting tool so that it can be used to impact the dialable component into locking engagement with the implant using the same instrument.

Abstract: A device for measuring a degree of bending of an intramedullary nail comprises a probe sized and shaped for insertion into a cannulation of an intramedullary nail. The probe including a first longitudinal element extending along a longitudinal axis from a distal end to a proximal end and a second longitudinal element extending along a longitudinal axis from a distal end to a proximal end, the distal ends of the first and second longitudinal elements attached to one another so that the longitudinal axes of the first and second longitudinal elements extend substantially parallel to each other and define a middle plane. A measuring element measures relative axial displacement of the proximal ends of the first and second longitudinal elements in the middle plane upon bending of the first and second longitudinal elements as the probe is inserted into a cannulation of the intramedullary nail.

Abstract: There is provided a method and system for determining a distal cut thickness and posterior cut thickness for a femur in a knee replacement operation, the method comprising: performing a tibial cut on a tibia; performing soft tissue balancing based on a desired limb alignment; measuring an extension gap between the femur and said tibial cut while in extension; measuring a flexion gap between the femur and the tibial cut while in flexion; calculating a distal cut thickness and a posterior cut thickness for the femur using the extension gap and the flexion gap and taking into account a distal thickness and posterior thickness of a femoral implant; and performing said femoral cut according to the distal cut thickness and posterior cut thickness.

Abstract: The invention relates to a distance measuring instrument for pedicle screws which detects the spacing between two pedicle screws (3, 3?) with the ends (26, 27) of two crossing limbs (11, 12) and displays it on a crossbar (25) fixedly connected to one of the limbs at a scale (22). Since the second limb (12) is divided into a pointer (16a) and into a flexural spring extending parallel to it at which a pronounced thumb grip (21a) is fastened, and since the thumb grip is connected to a scale (24) via which a pre-determined pre-tension can be read off relative to the pointer (16a), a spacing measurement can take place under a controlled pre-tension.

Abstract: An expandable shoulder trial for a reverse shoulder system is described. The trial includes a rotatably adjustable insert housed within a humeral cup. The insert has a proximal end and a distal end, the proximal end having a concave recess therein adapted to receive a glenosphere prosthesis. The distal end of the insert includes a shaft, the shaft having a helical groove disposed on at least a portion thereof. A distal end of the humeral cup is inserted in a humeral stem. The humeral cup has a proximal end including a recess therein, the recess defined by a circular wall. A guide pin protrudes from the circular wall and is adapted to engage the helical groove of the shaft of the insert. The proximal end of the insert may rotate along an axis toward the proximal end of the humeral cup and along the same axis away from the proximal end of the humeral cup.

Abstract: A distractor and measuring device includes a first handle operatively connected to a first paddle and a second handle operatively connected to a second paddle. The first and second handles are pivotally connected to one another such that movement of the handles relative to one another causes the paddles to move relative to each other. At least one transducer is positioned on at least one of the first and second handles for measuring an amount of force applied during distraction. A measurement rod is pivotally connected to the device and is movable in a longitudinal direction relative to the first and second paddles. A potentiometer is operatively connected to the measurement rod to measure the angular orientation of the measurement rod.

Abstract: A prosthetic trial for a joint prosthesis includes a stem having a proximal section and a distal section for implantation in a bone. A body includes a channel receiving at least the proximal section of the stem. A locking mechanism is at least partially disposed within the body. The locking mechanism is biased into a locking position in which the mechanism locks the stem within the first channel of the body. The locking mechanism is accessible outside said body to be pulled into a releasing position to unlock the stem from the body.

Abstract: A distance indicator for indicating the distance that a device has traveled includes an elongate housing with a guidewire connector configured for operative connection to a guidewire to hold the housing stationary with respect thereto. A plunger is operatively connected to the housing for longitudinal motion with respect to the housing. A first plunger end is configured to operatively contact the device. As the guidewire connector is holding the housing stationary with respect to the guidewire, the first plunger end is placed into operative contact with the device with the plunger and housing in a first relative plunger/housing position. The device moves longitudinally. The plunger moves into a second relative plunger/housing position assisted by the operative connection between the first plunger end and the device. The longitudinal difference between the first and second relative plunger/housing positions indicates a distance that the device has moved longitudinally with respect to the guidewire.

Abstract: A method and system for monitoring impaction of a femoral component of a hip prosthesis into a femur in which impaction data generated during the impaction of the femoral component into the femur is received from at least one measurement transducer attached to the femoral component and is normalized by a data acquisition and analysis device. An impaction monitoring metric is calculated based on the normalized impaction data, and femoral component fit and stability data is then generated and output to a user interface based on the impaction monitoring metric.

Abstract: A method for estimating at least one of a fastener-hole depth and a fastener length prior to forming a hole in a bone can include selecting a position on a proximal side of a proximal cortical bone layer for forming the hole, transmitting a transmitted wave into the bone from the selected position, and receiving a reflected wave at the selected position after the transmitted wave has been reflected by a distal cortical bone layer. The method can further include determining a distance from the selected position to the distal cortical bone layer based on times at which the transmitted wave is transmitted and the reflected wave is received, and estimating the at least one of the fastener-hole depth and the fastener length based on the distance to the distal cortical bone layer.

Abstract: Methods for predetermining a contour of a resected bone surface and assessing a fit of a prosthesis on the resected bone surface, for designing prostheses to fit discrete patient populations, and for designing customized prostheses.

Abstract: A method for treating fractures comprises positioning a bone fixation device along a bone and creating a first hole from an outer surface of the bone through a lateral cortex to a central portion thereof, the first hole corresponding to a position at which a first bone fixation element receiving opening is to be located when the bone fixation device is coupled to the bone in a desired orientation in combination with inserting and pushing a probe through the central portion of the bone until a tip of the probe contacts an interior structure of the bone providing resistance to penetration by the probe increased relative to the central portion of the bone and determining a first length of the portion of the probe extending into the bone via the first hole to select a desired length of a first bone fixation element to be inserted therethrough.

Abstract: Methods and instruments for repairing a damaged acetabular labrum. The arc length of a portion of an acetabular rim proximal to the damaged (torn or broken) region of the acetabular labrum is measured, and a graft, such as a meniscal allograft or a gracilis autograft, is trimmed according to the measurement and secured in the damaged region of the acetabular labrum as a replacement. Various instruments, such as a wheel mounted on an arm, a measuring member with spaced tines, or a hollow arm with a graduated wire, can be used to measure the arc length of the damaged region of the acetabular labrum.

Abstract: A patella clamp has a first part including a reference surface engageable with the anterior surface of a patella. The first part includes a stop surface spaced from the reference surface. A second clamping part is provided which is moveable with respect to the first clamping part. A cutting element coupled to the first clamping part is moveable with respect to the first part. The cutting element includes a shaft with an adjustable collar mounted on the shaft for movement with respect to the longitudinal axis of the shaft and cutting element. The adjustable collar on the shaft is engageable with a stop surface on the first part for spacing the cutting element a desired distance from the reference surface. A pair of gages are provided for selectively setting the position of the adjustable collar with respect to either the amount of patella bone being removed or the amount of patella bone remaining.

Abstract: Device for measuring the internal rotation of a hip joint, whereby the following steps are performed: a) Positioning a person to be examined (1) on the seating surface (8) of a chair-like positioning aid (5) in a sitting position; b) Fixating at least one of the upper thighs to be examined (3) of the person (1) on the seating surface (8) against translational motions, so that a rotation of the upper thigh (3) around its longitudinal axis is still possible; c) Moving the corresponding lower thigh (4) across the sagittal plane (20) by using a force K of a constant value Z acting on the lower thigh (4), so that the distal end of the lower thigh (4) is deviated from the sagittal plane; and d) Measuring the angle ? between the sagittal plane (20) and the longitudinal axis of the lower thigh (4).

Abstract: A sizing caliper for determining the optimum size of a femoral component of a knee prosthesis includes a caliper body, a drill guide body, a stylus tower and a graduated stylus slidably coupled to the stylus tower. The caliper body, the drill guide body and the stylus tower are slidably linked to each other by a linkage pin laterally extending there through in a manner thereby when the caliper body and the stylus tower are linearly displaced in opposite directions in reference to the drill guide body, the caliper body and the stylus tower are linearly displaced at an equal rate with respect to the drill guide body.

Abstract: A computer-assisted orthopaedic surgery system includes a device for generating a three dimensional geometrical surface model of a first bone and a database containing three 3 dimensional implant models of a plurality of available implants. The system includes a computer that is configured to permit a user to select from the database a first implant and display on a screen the three dimensional implant model of the first implant. The computer superimposes on the screen the implant model on top of the model of the first bone such that the two models are visually identifiable from one another.

Abstract: The invention relates generally to orthopaedic implants, and more particularly to orthopaedic implants having data acquisition capabilities and their use in monitoring and diagnosing fracture healing. RSA is also disclosed as a method for measuring inter-fragmentary movement in long bone fractures in order to confirm whether the fracture is reduced and for detecting changes in stiffness of the healing callus.

Abstract: A computer aided surgery system, method, surgical method and instrument for guiding the positioning of an acetabular cup in a pelvis are described. The position of the transverse acetabular ligament of the pelvis and the position of the acetabular labrum of the pelvis are determined. The orientation of an acetabular plane including the acetabular labrum and the transverse acetabular ligament is calculated. A planned position for the acetabular cup is determined, in which an inlet plane of the cup is substantially parallel to the acetabular plane. The instrument comprises a mounting for attaching the instrument to a patient, a support, a guide defining a longitudinal axis, and for receiving a further instrument bearing the acetabular cup implant, and an adjustment mechanism. The adjustment mechanism can allow the angular orientation of the guide to be adjusted about at least two different axes to allow the inclination and version or anteversion of the longitudinal axis to be altered.

Abstract: A robotic system that includes a remote controlled robot. The robot may include a camera, a monitor and a holonomic platform all attached to a robot housing. The robot may be controlled by a remote control station that also has a camera and a monitor. The remote control station may be linked to a base station that is wirelessly coupled to the robot. The cameras and monitors allow a care giver at the remote location to monitor and care for a patient through the robot. The holonomic platform allows the robot to move about a home or facility to locate and/or follow a patient.

Abstract: Disclosed is a method of selecting a femoral prosthetic for implantation relative to a femur using a femoral sizing guide. An extension portion of the femoral sizing guide is placed adjacent to a posterior condyle surface of the femur. A stylus is located proximate to an interior condyle surface of the femur. A first actuator disposed between the extension portion and a base portion is moved to rotatably displace the extension portion with respect to the base portion until the stylus is centrally located on top of the interior condyle. A measurement of the femur is identified with the sizing guide based on a relative location of the stylus, the extension portion and the base portion. A femoral prosthesis is selected based on the measurement.