Orthopaedic impactor

Abstract

An orthopaedic impactor includes a coil gun with a series of electromagnetic coils arranged along a barrel, and a mover configured to travel along the barrel under the influence of magnetic fields generated by the coils. The mover is monolithically formed from ferromagnetic metal, weighs less than 50 grams, and is shorter than the barrel, with a strike face designed to impact an impact face at the barrel's distal end, transferring energy to an attached orthopaedic implement. A controller interfaces with a firing circuit to sequentially energise the coils according to a firing sequence and is connected to a position sensor to detect the mover's position relative to the barrel. Based on the detected position, the controller dynamically adjusts the timing of the firing sequence, allowing the mover to strike the impact face at a specified target velocity, ensuring precise control over impact force.

Description

Orthopaedic ImpactorField of the Invention

[0001] The invention relates to orthopaedic surgical instruments, and more specifically, to a handheld orthopaedic impactor designed to deliver precisely controlled impact forces during the placement of orthopaedic implants and tools within a patient’s skeletal structure. The invention aims to improve the precision, safety, and efficacy of implant fixation and alignment by incorporating advanced mechanisms for controlling impact energy, enabling the surgeon to achieve reliable and reproducible results during orthopaedic procedures.Background of the Invention

[0002] An orthopaedic impactor is a manual medical instrument used in orthopaedic surgery to precisely drive orthopaedic tools, such as cutters, reamers, or orthopaedic components like femoral or acetabular hip replacement parts, into the patient’s bones. Typically operated by striking with a mallet or similar manual tool, the impactor is designed to deliver controlled force, ensuring proper fixation and alignment of these tools and components during surgery. Achieving a secure and stable attachment of orthopaedic implants is essential for the implants' long-term stability and functionality, and precise positioning within the patient’s anatomy contributes significantly to the surgery's overall success.

[0003] Manual orthopaedic impactors, though widely used, present inherent challenges. Controlling the impact force is difficult, requiring considerable skill and experience to avoid excessive force, which can lead to bone fracturing and other undesired surgical outcomes. Variability in force due to manual striking increases the risk of inadvertently damaging surrounding tissues or causing fractures. As a result, surgeons face a trade-off between delivering sufficient force to secure the implant and avoiding excessive force that might injure the bone or surrounding structures, both of which are critical for the procedure’s success.

[0004] To address these challenges, various automatic impactors have been developed. For instance, US20230240735A1 (Doyle, 2024) discloses an orthopaedicimpactor comprising a strike assembly arranged to impart force to an object, and a winding designed to receive an electric current, thereby generating a magnetic field. The magnetic field interacts with the strike assembly to cause movement, allowing the assembly to impart a controlled force to the object. This design seeks to replace the variability of manual striking with a controlled, consistent force.

[0005] Another arrangement is described in US20220226033A1 (Slocum et aL, 2022), which discloses a linear electric surgical hammer. This impact tool includes a motor that drives a slider along a longitudinal axis in both directions. The motion of the slider in each direction allows it to contact a series of collars, thereby delivering controlled impacts. By enabling bi-directional movement with precise force control, this design aims to reduce reliance on manual strikes and improve the precision of impact force application in orthopaedic surgeries.

[0006] While these advancements aim to address limitations of manual impactors, further improvements are sought to enhance control over impact energy and minimise risks of bone damage.Summary of the Disclosure

[0007] The disclosed orthopaedic impactor comprises a coil gun with a series of electromagnetic coils arranged along a barrel. The system includes a lightweight mover, configured to travel along the barrel under the influence of magnetic fields generated by sequentially energised electromagnetic coils. The mover defines a strike face designed to impact an impact face at the distal end of the barrel, transferring kinetic energy to an orthopaedic implement.

[0008] The impact energy imparted by the mover is determined by the kinetic energy formula: KE = %nw2, where m represents the mass of the mover, and v is the mover’s speed immediately prior to impact. Unlike prior art devices such as those in Doyle and Slocum, which use relatively heavy movers (for example, a 4 kg mover at 1 m / s to deliver 2 J of energy), the present arrangement utilises a substantially lighter mover, weighing less than 50 g, preferably around 30 g, while achieving much higher impact velocities, such as in excess of 6 or even 8 m / s.

[0009] The reduced mass of the mover not only facilitates the impactor’s lightweight design but operating at higher velocities, such as in excess of 6 m / s, allows a greater proportion of kinetic energy to be transmitted directly to the impacting tool. At these higher speeds, the inertia of the impactor's body resists absorbing the kinetic energy generated by the lightweight mover, ensuring that more of the energy is delivered to the orthopaedic tool upon impact. In contrast, at lower velocities, a significant portion of the impact energy is absorbed by the body of the impactor itself, reducing the energy effectively transferred to the tool. This high-velocity operation thus enhances the efficiency of force delivery to the orthopaedic implement, enabling a more precise and controlled impact with minimal energy loss to the impactor structure.

[0010] To meet the technical demands of this configuration, the mover is monolithically formed from ferromagnetic metal to endure high impact forces without incorporating polarised magnets, as required by Lorentz force motors disclosed by Slocum et al. Instead, the present design functions similarly to a Linear Switched Reluctance Motor (LSRM). In this setup, the controller manages a firing circuit to sequentially energise the electromagnetic coils along the barrel according to a precisely timed firing sequence. This creates a travelling magnetic field along the length of the barrel that pulls the mover forward in discrete steps, controlled by the timing and order of coil activation. Each coil is energised momentarily to attract the mover and de-energised just as the mover advances to the subsequent coil, resulting in a controlled, progressive acceleration along the barrel.

[0011] Additionally, the controller interfaces a position sensor to detect the mover’s real-time position within the barrel. Such position detection used to ensure accurate timing for coil activation, enabling smooth and efficient motion of the mover. By detecting the mover’s position along the stator, the controller can activate each coil precisely as the mover reaches it, optimising the magnetic pull and avoiding inefficient motion or stalling.

[0012] Position feedback also enables controlled acceleration and deceleration, allowing the mover to reach a specific target speed or to vary speed as required for to deliver a requisite amount of impact energy. For example, based on this detectedposition, the controller may adjust the timing of the coil activations to maintain the mover’s acceleration profile and achieve the desired target velocity and impact energy for reliable, precise operational control.

[0013] Other aspects of the invention are also disclosed.Brief Description of the Drawings

[0014] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[0015] Figure 1 shows a schematic of an orthopaedic impactor comprising a coil gun with a series of electromagnetic coils arranged along a barrel.

[0016] Figure 2 shows a cross-sectional view of the impactor, where the annular mover travels along a central guide rail.

[0017] Figure 3 shows the adapter interfacing with the orthopaedic implement attached to the impactor.

[0018] Figure 4 illustrates the firing sequence for the sequential energisation of the electromagnetic coils along the barrel, as managed by the controller.

[0019] Figure 5 plots the velocity of the mover against its position along the barrel, indicating target velocities for achieving specific impact energy levels.Description of Embodiments

[0020] Figure 1 shows a schematic of an orthopaedic impactor 100 comprising a coil gun 101 with a series of electromagnetic coils 102 arranged along a barrel 103. The barrel 103 houses a mover 104 configured to travel along the barrel under magnetic fields generated by the electromagnetic coils 102. The mover 104 defines a strike face 105, which impacts an impact face 106 at the distal end of the barrel 103 to transfer energy to an orthopaedic implement 107 attached to the impactor 100, as depicted in Figure 3.

[0021] The mover 104 may also have a proximal strike face 107 designed to impact a proximal impact face 108 for retraction. The impactor 100 includes a controller 109 with a processor 1 10 that interfaces with a memory device 1 1 1 via a system bus 1 12.In operation, the processor 1 10 retrieves computer program code instructions and associated data 1 13 from the memory 1 11 to execute the control functionality described here. The computer program instructions may be divided into various instruction modules 1 14. The processor 1 10 can interface with an I / O interface 1 15, allowing it to control peripherals, including a digital display 1 16 for displaying a user interface 1 17. Additionally, the processor 1 10 may connect to a data interface 1 18 to send and receive data over a local or wide area network 1 19. The controller 109 can receive operational parameters from the network 1 19 and transmit measured parameters back.

[0022] The mover 104 is engineered to be lightweight, operate at high speeds, and withstand significant impact forces. For example, the mover 104 may weigh less than 50 g and, in some designs, weigh approximately 30 g. The mover 104 is less than the length of the barrel 103 and is preferably not longer than an interval between adjacent coils 102.

[0023] The energy delivered upon impact by the mover 104 can be calculated using the kinetic energy formula:1, E = —mv2

[0024] where E is the impact energy, m is the mass of the mover 104, and v is the impact velocity.

[0025] To deliver an impact energy of 1 J with a 50 g (0.05 kg) mover:12E 12 X 1J v = — = L « 6.32 m / s J m I 0.05 kg

[0026] If the mover weighs 30 g (0.03 kg), the velocity required to deliver 1 J of energy|2 x 1 v 8.16 m / sJ 0.03

[0027] The mover 104 is constructed from ferromagnetic material to endure significant forces upon impact with the impact faces 106 and 108 of the barrel 103 and is devoid of permanent polarised magnets or assemblies which could disassemble under high impact force. Preferably, this ferromagnetic material is alloy steel, which may be carburised to enhance surface hardness and wear resistance. Carburising is a heat treatment process where carbon is diffused into the surface layer of the steel, resulting in a hard, wear-resistant surface while maintaining a tough core — ideal for repeated impact applications.

[0028] A suitable alloy for the mover 104 is a chromium -nickel-molybdenum alloy steel such as EN39B. EN39B provides high strength, toughness, and wear resistance after heat treatment, making it well-suited to withstand the repeated high-force impacts encountered by the mover 104.

[0029] The controller 109 manages a firing circuit 120 to sequentially energise the electromagnetic coils 102 along the barrel 108 according to a firing sequence 121 shown in Figure 4. The controller 109 is also connected to a position sensor 122, which detects the real-time position of the mover 104 along the barrel 108.

[0030] To further enhance position detection accuracy, the position sensor 122 preferably comprises a plurality of light beam interrupt sensors 138 positioned along the length of the barrel 108. Each interrupt sensor 138 incorporates a transmitter 139, configured to emit a collimated beam of light 140 across the barrel, which is detected by a precisely aligned optical receiver 141 on the opposite side. As the mover 104 travels along the barrel 108 at high velocities, each light beam interrupt sensor 138 captures discrete positional data in real-time, allowing for a significantly high sampling rate critical for controlling the mover’s precise acceleration and deceleration.

[0031] This light beam interrupt arrangement provides superior temporal resolution and spatial accuracy in detecting the position of the mover 104, particularly given its high operational velocity. Unlike systems that measure inductance variations in the electromagnetic coils 102 to infer position, the optical interrupt sensors 138 offer direct and instantaneous feedback, eliminating the response time lag associated withinductive sensing. When inductance variations are used to detect the mover’s position, a delay arises due to the time-dependent nature of electromagnetic field adjustments within the coils 102, particularly as the mover 104 approaches and then recedes from each coil. This response time delay is inherently caused by the inductive circuit’s reliance on transient electromagnetic fluctuations, which can lag behind the mover’s rapid advancement, resulting in a temporal offset in the position data.

[0032] In contrast, the light beam interrupt sensors 138 provide immediate binary feedback — either the beam is uninterrupted, or it is blocked by the mover 104 — yielding precise and continuous position measurements that align with the mover’s high-speed progression along the barrel. As such, each beam interruption serves as a precise positional marker, allowing the controller 109 to track the mover's position with millimetre or even sub-millimetre accuracy, far exceeding the temporal precision achievable through inductance-based systems.

[0033] Figure 2 shows a cross-sectional view of the impactor 100, where the annular mover 104 travels along a central guide rail 134. The impactor 100 can be powered via an electrical lead 135 or may incorporate an internal rechargeable battery or supercapacitor. It may operate at a safe voltage level but may include step-up converters to increase the voltage to over 400 V and the current needed to generate sufficient magnetic fields to accelerate the mover 104 to the desired speed.

[0034] The impactor 100 may be designed to be compact and handheld, with a body 136 typically less than 7 cm in diameter and approximately 10-15 cm in length. The digital display 1 16 may be adjustably mounted at the distal end of the body 136 for ease of use.

[0035] The distal end of the impactor 101 includes a connector 1 13 that may attach to an adapter 134 (Figure 3) interfacing the orthopaedic implement 107. The energy delivered by the mover 104 upon impact is transmitted through the connector 133 and adapter 134 to drive the orthopaedic implement 137 into bone. Preferably the adapter 134 is light weight so that its inertia doesn’t substantially retard the delivery of kinetic energy to the orthopaedic tool 107.

[0036] The controller 109 is designed to dynamically adjust the timing of the firing sequence 121 based on the detected position of the mover 104, ensuring that it strikes the impact face at the target velocity to deliver a requisite impact energy requirement.

[0037] In the operational overview 123 shown in Figure 4, the controller 109 determines the required energy at step 124, which can be set via the user interface 1 17. For instance, a surgeon can specify that each strike should deliver 1 J of energy. Alternatively, the controller 109 can determine the energy based on parameters specific to the patient or tool, retrieved from a lookup table.

[0038] At step 125, the controller 109 sets the starting position for the mover 104. In some embodiments, the starting position is at the rear end of the barrel 106, where the controller ensures the mover 104 is held in position by controlling the electromagnetic coils 102. Additionally, the controller 109 may adjust the impact energy by altering the travel distance of the mover 104 — a shorter travel distance results in lower energy.

[0039] At step 126, the controller 109 initiates the firing sequence 121 to accelerate the mover 104 along the barrel 106, allowing it to strike the distal impact face 106 and deliver the specified energy to the orthopaedic implement 107.

[0040] The firing sequence includes the use of the position sensor 122 to detect the real-time position of the mover 104 at step 126. Based on this position data, the controller 109 adjusts the timing of the coil activations at step 127 to ensure that the mover 104 reaches the distal impact face 106 at the target velocity, thereby delivering the required energy.

[0041] Figure 5 plots the velocity of the mover 104 against its position along the barrel 106. The plot illustrates the target velocity Vt2 needed to achieve 1 J of impact energy, with plot 133A showing the increase in the mover's velocity as it accelerates towards Vt2.

[0042] The controller 109 uses the position sensor 122 to monitor the mover 104 at sampling positions d1 through d4 along the barrel 103. If the velocity is below the target at a sampling point, the controller 109 can increase the acceleration by adjusting the coil timings. Conversely, if the velocity is above the target, the controllercan reduce acceleration, maintaining the mover's velocity trend towards the target to ensure precise energy delivery.

[0043] The higher target velocity Vt 1 , which corresponds to delivering 2 J of energy, is also shown in Figure 5. The controller 109 would increase the rate of acceleration so that the mover 104 approaches Vt1 for this higher energy delivery.

[0044] The controller 109 can affect the mover's acceleration by adjusting the operation timing between adjacent electromagnetic coils 102. Shorter intervals result in higher acceleration, allowing fine control over the mover's speed.

[0045] In step 128, the controller 109 may also adjust the current applied to the electromagnetic coils 102, modifying the magnetic field strength and thereby altering the mover’s acceleration as needed to meet the desired impact energy.

[0046] In some embodiments, immediately following an impact, the controller 109 is configured to detect the displacement of the orthopaedic implement 107 and dynamically adjust the impact energy delivered. For example, the controller 109 may advance the orthopaedic implement 107 by 1 mm with each impact, setting the mover 104 to strike the distal impact face 106 with an initial impact velocity of 6 m / s. However, if the controller 109 detects that the orthopaedic implement 107 has advanced by only 0.7 mm, it may increase the impact velocity to, for example, 7 m / s.

[0047] In certain embodiments, the impactor 100 includes an accelerometer interfacing with the controller 109, where acceleration measurements are used to calculate displacement of the impactor 100, and thereby the advancement of the orthopaedic implement 107. However, accelerometer readings may be less accurate due to the high-velocity operation of the mover 104. Therefore, in some embodiments, the impactor 100 is designed to measure displacement directly between the orthopaedic implement 107 and the body 136 of the impactor 100. In such cases, a magnet can be applied to the adapter body 134, with a Hall effect sensor located at the distal end of the body 136, configured to detect the magnetic field strength of the magnet. This field strength is affected by the relative offset between the adapter 134 and the body 136. Specifically, under high-velocity impact, the adapter 134 will be displaced forward before the body 136 follows, creating a transition period. Duringthis period, the controller 109 can detect changes in the magnetic field strength from the Hall effect sensor to calculate the displacement of the orthopaedic implement 107 with respect to the impactor 100.

[0048] The controller 109 may also be configured to vary the impact energy delivered by the coil gun according to an impact energy profile. For example, insertion may begin with an impact energy of 1 J, increasing according to a decaying exponential to a maximum of 10 J over 100 impacts or an insertion distance of 7 cm. This allows insertion to conclude with maximum impact force. Various impact energy profiles can be pre-programmed in memory 11 1 for user selection through the interface 1 17.

[0049] In some embodiments, the impact energy profile can be dynamically adjusted based on parameters, including patient-specific factors such as bone density, age, orthopaedic implement type, and similar considerations.

[0050] In cases where the impactor 100 includes a force sensor, this sensor can detect the amount of force applied by the surgeon, enabling the controller 109 to adjust the firing circuit 120 to modulate the delivered impact energy accordingly. For example, if the surgeon exerts greater force on the impactor 100, the controller 109 will adjust the firing circuit 120 in response to the detected position of the mover 104, causing it to strike the distal impact face 106 at a proportionately higher velocity, thereby delivering an impact energy that corresponds to the force applied by the surgeon.

[0051] The controller 109 can also be configured to measure impact resistance. This impact resistance may be inferred from displacement measurements as previously described. For instance, with a constant impact energy setting, a smaller displacement measurement indicates higher impact resistance, while a larger displacement measurement suggests lower impact resistance. During insertion, the controller 109 can ensure that impact resistance remains within upper and lower threshold limits.

[0052] Unexpectedly low impact resistance (i.e., below the lower threshold) during cutting may indicate a bone fracture, while unexpectedly high impact resistance (i.e., above the upper threshold) could suggest that the reamer is stuck in the bone duringextraction. The controller 109 may be configured to automatically halt the operation of the coil gun 101 upon detecting either of these out-of-bounds conditions and can control the user interface 1 17 to display a warning. Additionally, an audible alert may be triggered to notify the surgeon.

[0053] In one embodiment, the orientation of the impactor 100 is fixed relative to the orthopaedic implement 107 by a coupling 1 13, and the impactor may include an orientation sensor that allows the user interface 1 17 to display the measured angular orientation (version) or alignment (varus / valgus). The user interface 1 17 can display a bull’s-eye with a moving target to visually guide the surgeon in achieving the correct angular orientation and alignment.

[0054] Furthermore, the impactor may include a torque sensor to measure the torque applied between the impactor 100 and the orthopaedic implement 107.

[0055] In an alternative embodiment, a universal coupling is used to interface the impactor with the orthopaedic implement 107, allowing the impactor 100 to apply omnidirectional impact forces that are converted to unidirectional force along the longitudinal axis of the orthopaedic implement 107. This universal coupling may include a semispherical bearing with a curved surface designed to receive omnidirectional impact forces.

[0056] The orthopaedic impactor 100, as described herein, is used during orthopaedic procedures to drive implants or tools precisely into a patient’s skeletal structure, minimising the risk of bone damage and ensuring optimal fixation and alignment of orthopaedic components. According to an exemplary method of use, the surgeon begins by attaching the orthopaedic implement 107 to the adapter 134, ensuring it is securely engaged with the impact face 106 of the impactor 100, as illustrated in Figure 3. The controller 109, in communication with the digital display 1 16, allows the surgeon to set a target impact energy level — typically 1 J for initial placement and potentially up to 10 J for final fixation. The display provides feedback on operational parameters, such as the selected impact energy, target velocity, and angular alignment of the impactor.

[0057] Once parameters are set, the surgeon positions the impactor 100 at the designated point of insertion on the patient’s bone. Activating the system initiates the controller’s firing sequence, sequentially energising the electromagnetic coils 102 along the barrel 103 to accelerate the mover 104. The position sensor, illustrated in Figure 4, continually monitors the real-time position of the mover and dynamically adjusts the timing of coil activation to maintain the target velocity.

[0058] As the mover approaches the distal impact face 106, the controller ensures that the target velocity is achieved. Upon impact, the kinetic energy of the mover is transferred through the adapter 134 to drive the implant component into the bone. The high-speed operation, combined with the lightweight mover design, minimises the energy lost to the impactor’s body, resulting in effective energy transfer to the orthopaedic implement.

[0059] The impactor may allow the surgeon to make real-time adjustments. If the controller detects unexpectedly low resistance, indicating excessive implant advancement or possible bone fracture, it will halt operation and alert the surgeon via the user interface. Conversely, higher-than-expected resistance, such as from a lodged implant, prompts the system to increase impact energy gradually until resistance thresholds return to acceptable limits.

[0060] The user interface may offer visual guidance, showing a bull’s-eye alignment display to assist the surgeon in maintaining precise angular orientation during impact. Additionally, the torque sensor measures rotational forces applied to the implement.

[0061] In a final adjustment phase, the surgeon may select a customised impact energy profile to finalise implant positioning. For instance, the controller can adjust the firing circuit to increase energy in a decaying exponential pattern, starting from 1 J and incrementally increasing to a maximum of 10 J over a set number of impacts.

[0062] Following implant placement, the surgeon may verify the stability and alignment of the implant using the impactor’s built-in sensors. If adjustments are needed, the controller allows repeated, precisely controlled impacts until optimal placement is achieved.

[0063] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practise the invention. Thus, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed as obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following claims and their equivalents define the scope of the invention.

Claims

Claims1 . An orthopaedic impactor comprising: a coil gun comprising a series of electromagnetic coils arranged along a barrel; a mover configured to move along the barrel under magnetic fields generated by the electromagnetic coils, wherein the mover is monolithically formed from ferromagnetic metal, is shorter than the barrel, weighs less than 50 g, and defines a strike face to impact an impact face at a distal end of the barrel to impart impact energy to an orthopaedic implement connected to the impactor; a controller interfacing with: a firing circuit to sequentially energise the electromagnetic coils along the barrel according to a firing sequence; and a position sensor configured to detect the position of the mover relative to the barrel, wherein the controller is configured to dynamically adjust the timing of the firing sequence based on the detected position of the mover so that the mover strikes the impact face at a target velocity.

2. The orthopaedic impactor of claim 1 , wherein the controller is configured to accelerate the mover to a velocity in excess of 6 m / s.

3. The orthopaedic impactor of claim 1 , wherein the mover weighs less than 50 g and the controller is configured to accelerate the mover to a velocity in excess of 8 m / s.

4. The orthopaedic impactor of claim 1 , wherein the ferromagnetic metal is alloy steel.

5. The orthopaedic impactor of claim 4, wherein the alloy steel is carburised.

6. The orthopaedic impactor of claim 4, wherein the alloy steel is a chromium-nickel- molybdenum alloy steel.

7. The orthopaedic impactor of claim 6, wherein the alloy steel is EN39B.

8. The orthopaedic impactor of claim 1 , wherein the position sensor comprises a plurality of light beam interrupt sensors arranged along the length of the barrel.

9. The orthopaedic impactor of claim 8, wherein the controller is configured to determine impact displacement and dynamically vary the target velocity quarterly.

10. The orthopaedic impactor of claim 9, further comprising an accelerometer interfacing with the controller, wherein acceleration measurements from the accelerometer are used to calculate the impact displacement.1 1 . The orthopaedic impactor of claim 9, further comprising a Hall effect sensor configured to detect the impact displacement between the orthopaedic implement and the body of the impactor by detecting changes in magnetic field strength due to relative movement of a magnet fixed relative to the orthopaedic implement.

12. The orthopaedic impactor of claim 1 , wherein the controller is configured to vary the impact energy delivered by the coil gun according to an impact energy profile.

13. The orthopaedic impactor of claim 12, wherein the impact energy profile is a decaying exponential.

14. The orthopaedic impactor of claim 1 , further comprising a force sensor configured to detect the force applied by a surgeon to the impactor, wherein the controller adjusts the firing circuit to control the impact energy delivered in response to the detected force.

15. The orthopaedic impactor of claim 1 , wherein the controller is configured to detect impact resistance from displacement measurements, such that a smallerdisplacement measurement indicates higher impact resistance and a larger displacement measurement indicates lower impact resistance.

16. The orthopaedic impactor of claim 15, wherein the controller is configured to halt the operation of the coil gun when the impact resistance falls outside pre-set upper and lower threshold values.

17. The orthopaedic impactor of claim 1 , further comprising an orientation sensor configured to measure the angular orientation of the impactor relative to the orthopaedic implement and display the orientation on a user interface.

18. The orthopaedic impactor of claim 17, wherein the user interface displays a bull’s- eye with a moving target to assist a surgeon in achieving correct angular orientation and alignment.

19. The orthopaedic impactor of claim 1 , further comprising a torque sensor configured to measure the torque applied between the impactor and the orthopaedic implement.

20. The orthopaedic impactor of claim 1 , further comprising a universal coupling interfacing the impactor and the orthopaedic implement to convert omnidirectional impact force applied by the impactor into unidirectional force along a longitudinal axis of the orthopaedic implement.

21. The orthopaedic impactor of claim 20, wherein the universal coupling comprises a semispherical bearing with a curved surface configured to receive omnidirectional impact force.

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