Devices, assemblies and methods for inserting surgical implants - Patents.com

Abstract

A device for inserting a surgical implant into a bone (4) by impaction includes a percussion tool or impactor (10) for exerting a force on the surgical implant, at least one sensor (12) associated with the impactor (10), and a processing unit (30) connected to the sensor (12). The sensor (12) is configured to measure deformation of the impactor (10) and provide a measurement signal representative of the change in deformation over time during impact. The processing unit (30) calculates an index representative of the level of contact between the surgical implant and the bone (4) based on the change in deformation over time of the impactor (10) during impact. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present invention relates to a device, assembly and method for inserting a surgical implant into bone by impaction. The device comprises a percussion tool or impactor for applying a percussive force (directly or indirectly) to the surgical implant in order to insert the surgical implant into the bone. [Background technology]

[0002] The concept of surgical implant in the present disclosure is not limited to the implant itself, but also includes medical devices that are temporarily inserted into bone, in particular, all orthopaedic prostheses that replace damaged joints (especially prostheses for artificial hips, knees, shoulders, elbows, spines or ankles) and the attachments used for the bones that receive such prostheses.

[0003] The forceful insertion of a surgical implant into bone often involves impaction using an impactor (typically a hammer), sometimes with an auxiliary tool, i.e. the surgeon using the impactor strikes the auxiliary tool and the impaction force is transmitted to the implant by the auxiliary tool.

[0004] As the number of impacts increases, the graft material becomes embedded in the bone. The level of contact between the graft material and the surrounding bone depends on this embedment. This level of contact is generally characterized by the BIC ratio, which represents the contact ratio of the graft surface with the bone. The BIC ratio is the percentage of the graft surface that is in contact with the bone. The more the graft material is embedded in the bone, the higher the BIC ratio.

[0005] Generally, the physician will want to monitor the embedding of the graft into the bone and determine the moment when the level of graft-to-bone contact is optimal (or at least satisfactory). The physician will also want to verify the primary stability of this graft. The success of the graft insertion procedure depends simultaneously on a sufficient level of graft-to-bone contact, a level of primary stability, and the absence of damage, including, among other things, the absence of fractures or microcracks of the bone during insertion. If the graft is not fully embedded in the bone and / or is not sufficiently stable, the graft will micromigrate and require further surgical procedures.

[0006] Therefore, a compromise must be made between having a high enough number of impacts to obtain a satisfactory level of bone-implant contact, and having a low enough number of impacts to prevent bone damage. However, it is difficult for the physician to assess the impact number with a high degree of confidence, especially when the physician should know exactly when to stop striking the impactor.

[0007] In this context, one of the aims of the present invention is to provide a device that is able to provide reliable information about the level of contact between the implant material and the bone during surgery, thereby enabling the surgeon to know when to stop applying the impactor blow.

[0008] French Patent No. 3019031 discloses a device for assisting the installation of orthopedic implants. The device comprises an impactor for applying a striking force to an impact surface coupled to the implant, thereby exerting a striking force on the implant. The impactor comprises a striking surface for applying a striking force to the impact surface. A force sensor is attached to the striking surface, converting the temporal variation of the applied striking force into a usable electrical signal. Summary of the Invention [Problem to be solved by the invention]

[0009] Although generally useful, the device of FR 3019031 has drawbacks in that the force sensor must fulfil several requirements. Firstly, the force sensor must have sufficient mechanical strength to withstand the mechanical stresses caused by the applied impact force. Also, the force sensor must be heat resistant, since the impactor and its sensor must be sterilised before the operation. The impactor and its sensor are typically subjected to high temperatures during sterilisation (e.g. in an autoclave at a pressure of 2 bar and a temperature of 134°C for 18 minutes). These requirements regarding mechanical strength and heat resistance significantly limit the choice from commercially available sensors. Moreover, sensors that fulfil these requirements are generally expensive.

[0010] There is therefore a need for a new type of device that is able to overcome (or minimize) the aforementioned drawbacks while still achieving the general objectives of the present invention. [Means for solving the problem]

[0011] The present invention relates to a device for inserting a surgical implant into a bone by impaction, the device comprising an impactor for applying a striking force to an impact surface coupled to the surgical implant, the impactor exerting a striking force on the implant.

[0012] The impactor is associated with at least one sensor configured to measure the deformation of the impactor and to provide a measurement signal representative of the change in this deformation over time during the impact.

[0013] The sensor (i.e., the at least one sensor as described above) is connected to a processing unit configured to calculate an index representative of a contact level between the surgical implant and the bone based on the change in deformation of the impactor over time during the impact. The electrical connection between the sensor and the processing unit may be wired or non-wired.

[0014] The proposed solution is based on the implementation of one or more deformation sensors coupled to the impactor and the acquisition, recording and analysis of measurement signals, which allow to determine an index representative of the level of contact between the surgical implant and the bone. If several sensors are used, the signals acquired by these sensors may be averaged or combined respectively to obtain a measurement signal on which the index is calculated.

[0015] In contrast to the force sensors used in the prior art, deformation sensors do not convert the impact force applied by the impactor into a usable signal, but rather the deformation of the impactor into a usable signal. Therefore, deformation sensors do not have to directly withstand the mechanical stress resulting from the applied impact force, and the requirements on the sensor in terms of mechanical strength are lower. Therefore, the choice of commercially available sensors is wider. And suitable sensors are generally less expensive than the force sensors used in the prior art.

[0016] The proposed device allows the surgeon to be informed in real time of the level of contact between the surgical implant and the bone during the surgical implant insertion procedure. In addition to reducing costs, the device has the advantage of being easy to use. In particular, the surgeon can use the device with the same movements as before, i.e., the surgeon does not need to learn new movements but can use the skills he has acquired when using conventional devices.

[0017] In addition to the aforementioned features, the proposed device may comprise one or more of the following features, which may be considered independent of each other or may be combined: the processing unit comprises a low-pass filter for attenuating frequency components in the measurement signal that are above a threshold value that is between 20% and 100% of the resonant frequency of the impactor; the processing unit comprises a low-pass filter for attenuating frequency components in the measurement signal that are higher than a threshold value lying between 1 kHz and 35 kHz, in particular between 5 kHz and 20 kHz The impactor has a striking surface for striking the impact element, an opposite surface opposite the striking surface, and a side surface extending between the striking surface and the opposite surface, and at least one sensor is arranged on the side surface or the opposite surface. The impactor has a front surface with a projection formed thereon, the front surface of the projection forming the striking surface of the impactor, and the sensor is mounted on a side surface of said projection.

[0018] In some embodiments, the proposed index corresponds to an average of the deformations calculated in a time window of programmable duration positioned in the measurement signal.

[0019] The start time of said time window may correspond to the time when the intensity of the measurement signal reaches a maximum value. The duration of this time window may then be between 0.1 ms and 5 ms, in particular between 0.1 ms and 0.5 ms or even 0.25 ms. Alternatively, the start of the time window may be defined by a certain delay (for example between 0 ms and 5 ms) from the time when the intensity of the measurement signal reaches a maximum value.

[0020] For example, the index (IN1) is calculated as follows:

number

[0021] Alternatively, the indicator is defined in the processing unit as the duration of the impact measured based on the measurement signal (i.e. the change in deformation over time during the impact). This duration corresponds to the time (ti2-ti1) between a time ti1 corresponding to the start of the impact and a time ti2 corresponding to the end of the impact. For example, the end time ti2 of the impact may be the instant at which the magnitude of the deformation becomes smaller than a predefined limit value.

[0022] In another embodiment, the index may correspond to the duration of a time window, where the start time of the time window is defined as the time corresponding to the first peak of the local maximum of the measured signal, and the end time of the time window is defined as the time corresponding to the second peak of the local maximum of the measured signal.

[0023] All these indicators represent the level of contact between the surgical implant material and the bone and constitute reliable indicators.

[0024] As a general rule, as the number of impacts increases, the contact level between the surgical implant and the bone tends to first increase and then stabilize. Once the surgical implant-bone contact level stabilizes, it is generally considered to be sufficient. The proposed indicator (indicating the contact level) also shows the same behavior and tendency: as the number of impacts increases, the indicator increases / decreases and then stabilizes around a stable value (above / below a threshold value). The value of the indicator in the above example decreases with the number of impacts and then reaches a nearly flat stable value.

[0025] From the behavior of the indicators, conditions for issuing an alarm (e.g. light, sound, vibration, etc.) can then be derived. The physician then knows when to stop striking the surgical implant, i.e. when the contact level between the surgical implant and the bone is optimal (possibly sufficient). Thus, the device in some embodiments further comprises an alarm system connected to the processing unit. This alarm system interacts with the processing unit to issue an alarm signal when said indicators converge to a satisfactory value during striking or when said indicators exceed a predefined threshold. This threshold may be empirically determined during tests or calculated. The tests may be performed, for example, on a cadaver, and the threshold is defined as the value at which the contact level between the surgical implant and the bone of the cadaver is deemed sufficient.

[0026] In some embodiments, the impactor is a hammer with a gripping shaft with a striking head on top. In particular, the impactor may have substantially the same shape and weight as impactors used in daily life, so that a skilled physician can handle it correctly. The sensor is attached to the striking head such that deformation of the striking head causes deformation of the sensor.

[0027] It is noted that the impact surface may be directly coupled to the surgical implant, in the sense that it may be a surface of the surgical implant. Alternatively, the impact surface may be indirectly coupled to the surgical implant, in the sense that it may be a surface of an instrument or auxiliary tool, which is in direct contact with the surgical implant. In the latter case, the impactor applies the impact force to the impact surface of the surgical implant via the auxiliary tool. In other words, the impact force is applied to the auxiliary tool and transmitted to the surgical implant by the auxiliary tool.

[0028] In some embodiments, the device further comprises an auxiliary tool having a rear end forming an impact surface and a front end for cooperating with the surgical implant, the impactor applying a striking force to the surgical implant via the auxiliary tool.

[0029] The front end of the auxiliary tool may cooperate with the surgical implant in simple contact. Alternatively, the front end of the auxiliary tool may be mechanically fixed to the orthopaedic implant in a removable manner (e.g. by a screw). Fixing the auxiliary tool to the surgical implant generally results in a better measurement signal. Once the surgical implant is correctly positioned, the auxiliary tool is easily removed.

[0030] The present disclosure also relates to an assembly comprising the aforementioned device and a surgical implant, in particular a femoral stem or an acetabular cup.

[0031] The present invention also relates to a method for inserting a surgical implant into a bone by means of impaction, the method comprising: The method includes providing the aforementioned device and a surgical implant. To insert the surgical implant, a striking force is applied to the surgical implant by using an impactor to strike an impact surface coupled to the surgical implant. An index is calculated which gives the level of contact between the surgical implant and the bone.

[0032] In some embodiments, the index may be calculated one or more times at the end of insertion of the surgical implant to ensure proper implantation.

[0033] Alternatively, the indicator may be calculated during successive strikes, with strikes on the impact surface being stopped once the indicator converges to a stable value or exceeds a predefined threshold.

[0034] The surgical implant may be, but is not limited to, an acetabular cup, where the cup is struck with an impactor to forcefully insert the cup into the cavity in the ilium, and an index may be calculated at the end of insertion to ensure the cup is properly implanted.

[0035] The advantages of such a method come from the advantages of the devices used.

[0036] The aforementioned features and advantages, as well as others, will become apparent upon reading the following detailed description of exemplary embodiments of the proposed device, which makes reference to the attached drawings, in which: [Brief description of the drawings]

[0037] The following drawings are schematic and not to scale, the main purpose of which is to explain the principles of the invention. [Figure 1] FIG. 1 is a schematic diagram of a device for inserting a surgical implant with an impactor having a deformation sensor. [Diagram 2] 2 is a graph showing an example of a signal obtained by the deformation sensor of FIG. 1; [Diagram 3] FIG. 13 is a schematic diagram of another example of an impactor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In FIG. 1, an example of a device 1 for inserting a surgical implant into a bone by impaction is shown. In this example, the implant is a prosthesis, in particular a prosthesis for an artificial hip joint. The majority of artificial hip joints generally comprise a first part attached to the femur and a second part attached to the pelvis. The first part comprises a femoral stem that is inserted into the medullary canal of the femur and an artificial head consisting of a spherical element. The artificial head is attached to the femoral stem and replaces the neck of the femur. The second part comprises an artificial acetabulum that is inserted into an acetabular cavity that is placed on the side of the ilium of the pelvis as a replacement for the acetabulum of the pelvis. The artificial acetabulum may comprise an acetabular cup. The acetabular cup is a generally metallic, approximately hemispherical element that is inserted into the cavity of the acetabulum. In the acetabulum an insert is placed with which the artificial head is articulated.

[0039] The implant material in FIG. 1 is an acetabular cup 2. This cup 2 is gradually inserted by impaction into a cavity 3 of the acetabulum of the ilium 4 of the patient's pelvis. The cavity 3 is prepared in advance by the physician to receive the cup 2. The cup 2 is inserted into the cavity 3 by impaction using an impactor 10 (typically a hammer). An auxiliary tool 20 may be used at this time. In this case, the physician strikes the auxiliary tool 20 with the impactor 10. The auxiliary tool 20 transmits the force of the impact to the cup 2. With an increasing number of impacts, the cup 2 is embedded in the cavity 3.

[0040] The auxiliary tool 20 is formed by a rigid rod 21. A knob with a domed surface is firmly fixed to the rear end of the rigid rod 21, forming an impact surface 22. Along its length, from the rear end to the front end, the rod 21 comprises the aforementioned knob, a portion forming a handle 24, a front portion, and a head 26 for gripping the cup 2. Front and rear in this case are defined as the directions in which the auxiliary tool 20 advances during insertion.

[0041] The device 1 also comprises a percussion tool or impactor 10, such as a hammer, with a gripping shaft 13 having a striking head 11 at the top. The head 11 has a striking surface 11a for striking an impact surface 22 of the auxiliary tool 20, an opposite surface 11b opposite the striking surface 11a, and a side surface 11c extending between the striking surface 11a and the opposite surface 11b. When the surgeon wishes to embed the cup 2 in the bone 4, he holds the handle 24 of the auxiliary tool 20 with one hand and the gripping shaft 13 of the impactor 10 with the other hand. The surgeon then strikes the impact surface 22 of the auxiliary tool 20 with the striking surface 11a of the impactor 10. The striking force generated by the impactor 10 is transmitted to the cup 2 via the auxiliary tool 20.

[0042] According to the invention, the impactor 10 is equipped with one or more sensors 12. This (or these) sensor(s) are intended to detect the deformation of the impactor 10 (more precisely the striking head 11) during each impact and to convert this deformation into a usable electrical signal.

[0043] In the example of FIG. 1, the impactor 10 comprises a deformation sensor 12 arranged on one of the side faces 11c of the striking head 11. In this case, the sensor 12 is arranged on the side face 11c that extends substantially parallel to the axial direction of the gripping shaft 13. More specifically, as can be seen from the side (see FIG. 1), the sensor 12 is mounted in front of the side face 11c, between the striking face 11a and the axis of the gripping shaft 13. This special arrangement of the sensor 12 on the striking head 11 allows to optimize the measurement of the deformation, which in turn conveys more useful information and allows to obtain a measurement signal that is more easily usable. In general, however, the deformation sensor or sensors 12 may be arranged on any face of the impactor 10 other than the striking face 11a (i.e. on the side face 11c or on the opposite face 11b).

[0044] Alternatively, as shown in Fig. 3, the impactor 10 has a front surface 11e on which a protrusion 9 is formed. The front surface 9a of this protrusion 9 forms the striking face 11a of the impactor 10. The sensor 12 is attached to the side of the protrusion 9 (i.e. the face of the protrusion 9 extending between the striking face 11a and the front surface 11e). The special positioning of this sensor 12 on the striking head 11 allows to optimize the measurement of the deformation and at least partially avoid resonances specific to the impactor 10, thereby obtaining a measurement signal that conveys more useful information and is more easily exploitable.

[0045] The deformation sensor 12 is attached to the striking head 11, for example by means of adhesive or other suitable fastening means, so that the deformation of the striking head 11 causes a deformation of the sensor 12. The sensor 12 is for example a gauge sensor with an elastic measuring element. The deformation of the elastic measuring element is first converted into a change in electrical resistance, which then generates an output electrical signal. Alternatively, the sensor 12 may be a piezoelectric sensor based on the piezoelectric properties of a material (for example quartz or artificial ceramics), which generates an electric charge with deformation. The sensor 12 is attached to the striking head 11, for example by means of adhesive or other suitable fastening means, so that the deformation of the striking head 11 causes a deformation of the sensor 12. By way of example, the deformation sensor 12 may be a sensor of the brand PI® (reference number PI255), measuring an area of ​​12x12 mm. It may be glued to the impactor 10 with an epoxy adhesive so as to withstand the temperatures in an autoclave.

[0046] The device 1 also includes a processing unit 30 connected to the sensor 12. The processing unit 30 is configured to evaluate the degree of insertion of the cup 2 into the bone 4 based on the measurement signals received from the sensor 12. The processing unit 30 comprises, for example, a microcontroller 34. The microcontroller 34 may be housed in an external housing 32. Alternatively, the processing unit 30 may be integrated with the impactor 10. Further alternatively (not shown), the processing unit 30 may be formed of a separate device, such as a microcomputer connected to a data acquisition module (which itself is connected to the sensor 12).

[0047] 1, the connection between the sensor 12 and the processing unit 30 is a wired connection using a cable 15. Alternatively, the measurement signal provided by the sensor 12 may be transmitted using a wireless connection, in which case the sensor 12 is equipped with an antenna or the like.

[0048] During each impact made by the surgeon with the impactor 10 and via the auxiliary tool 20 on the cup 2, the sensor 12 measures the deformation of the striking head 11 of the impactor 10 and gives a measurement signal representative of the time evolution of this deformation during the impact. The impact is considered to start at the moment of contact between the impactor 10 and the implant material (directly or indirectly via the auxiliary tool) and to last for a certain period of time from this moment onwards, in any case shorter than 50 ms. An example of a signal given by the sensor 12 is shown in figure 2 and explained below.

[0049] The inventors have analysed these measurement signals and found that they convey information about the contact level between the cup 2 and the bone 4. In particular, the inventors have succeeded in determining an index representative of the contact level between the cup 2 and the bone 4 based on the collected measurement signals, as will be explained below.

[0050] In the following, the link between the collected measurement signals and the bone-implant contact level is explained. The impactor 10 transmits a striking force to the cup 2 via the auxiliary tool 20. With regard to the system consisting of the impactor 10, the auxiliary tool 20, the cup 2 and the bone 4, when all these components are connected during the striking, the striking force is the source of vibration modes in this whole system. These vibration modes are essentially independent of the vibration modes of the bone-implant system (i.e. the bone-cup system). Essentially, the greater the bone-implant contact level, the stiffer the bone-implant system is and the higher the resonant frequency of the vibration modes.

[0051] In some embodiments, the processing unit 30 comprises a low-pass filter for attenuating frequency components in the measurement signal that are higher than a predefined threshold. In particular, this threshold is chosen to reduce the effect of the resonance of the impactor itself in the signal. The resonance frequency of the impactor is constant for a given impactor and is significantly higher than the frequency of the signal carrying information about the bone-implant material system. In particular, for the insertion of the cup 2 of FIG. 1, the impactor 10 has a resonance frequency of about 20 kHz or higher, whereas the frequency of the useful signal provided by the sensor 12 is below 5 kHz. The threshold may therefore be chosen between 5 kHz and 20 kHz.

[0052] The low-pass filter thus allows attenuating frequencies in the measurement signal that are close to (or higher than) the resonance frequency of the impactor 10, which is characteristic of the mode of vibration of the impactor 10 and does not convey information about the level of contact between the implant material and the bone, while retaining lower frequencies that are characteristic of the mode of vibration of the entire system made up of the impactor 10, the auxiliary tool 20, the cup 2 and the bone 4 and that convey information about the level of bone-cup contact. The quality of the measurement signal in terms of useful information is thus improved and the signal is easier to use.

[0053] FIG. 2 is a graph showing an example of signals obtained with the deformation sensor 12 for different bone-implant contact levels. These signals were obtained during four tests aimed at elucidating the correlation between the proposed indicators and the level of implant-bone contact. These four tests were carried out with four samples of bovine bone purchased at a butcher's shop. For each sample, a cavity was made under the same conditions and with the same instruments as in the surgical procedure. A cup 2 was then placed in the cavity and the same impact force as in the clinic was applied. For each sample, the cup 2 was pressed until it was completely embedded in the bone. Once the cup was completely embedded, the cup 2 was gently struck with the impactor 10 of FIG. 1. This gentle strike was not aimed at changing the position of the cup 2 in the bone, but at calculating an indicator based on the measurement signals transmitted by the deformation sensor 12. Once the indicators were calculated, the cup 2 was removed from the bone by applying a tensile force along the axis of the cup 2 to the cup 2. This tensile or tearing force reflects the contact level between the implant and the bone. That is, the greater the level of bone-implant contact, the more difficult it is to pull the implant from the bone and the greater the tear force.

[0054] In the graph of Figure 2, time t in milliseconds (ms) is plotted on the x-axis, and the normalized voltage u of the electrical signal provided by the sensor 12 during the four aforementioned tests is plotted on the y-axis. This voltage is directly proportional to the deformation of the striking head 11 measured by the sensor 12. These four signals are labeled S1 to S4. These signals have been normalized and filtered.

[0055] For each signal, the index IN1 was calculated as follows:

number

[0056] In this example, times t1 and t2 are identified in FIG. 2 and were determined by running an optimization process.

[0057] The table below gives the calculated index value and the measured tear force (in Newtons) for each signal S1 to S4. [Table 1]

[0058] These results indicate that a correlation exists between the proposed index and the tear force (and therefore between the proposed index and bone-implant material), and therefore the index can be used to evaluate the bone-implant material contact level.

[0059] With reference to FIG. 1, the device 1 may include a warning system 33 for issuing a warning signal (e.g., an audio, visual and / or tactile signal). The warning system 33 is connected to the processing unit 30. The warning system 33 interacts with the processing unit to warn the physician when the contact level between the cup 2 and the bone is considered sufficient based on the indicator IN1 (e.g., as soon as the indicator IN1 falls below the threshold value S1 or when this indicator IN1 becomes stable). As a result, the physician has reliable information in real time that indicates that a sufficient level of bone-implant contact has been reached. This allows the physician to decide to stop striking the cup 2. This reduces the risk of damage to the bone 4, in particular the risk of fractures and microcracks of the bone.

[0060] The above example of inserting the cup 2 into the ilium 4 is given as a non-limiting explanation. A person skilled in the art can easily use the indicators proposed by the inventors for other types of implants without departing from the scope of the present invention. In other words, the cup 2 and the bone 4 are only examples of a surgical implant and a bone, respectively, in the sense of the present invention.

[0061] In particular, the proposed device may be used for implants for hip joint prostheses other than acetabular cups (e.g. femoral stems), knees, shoulders, spines, ankles, etc., and more generally for any type of surgical implant that requires forcible insertion into the bone by impaction. It may also be used for the temporary insertion of a surgical instrument into the patient's bone, for example a surgical file, such as a femoral file for a hip joint prosthesis. In order for the medullary canal to be able to receive a femoral stem, the femoral file is designed to be inserted into the medullary canal by impaction. These files are struck directly by the impactor, with or without the intermediation of an auxiliary tool. When no auxiliary tool is used, the impact surface is constituted by a surface arranged at the rear end of the grip of the file.

[0062] Finally, the various features of the above-mentioned embodiments may be independent of each other or may be combined. When they are combined, these features may be as described above or may be different. The present invention is not limited to the specific combinations described above. Unless otherwise specified or there is no technical contradiction, the above-mentioned embodiments or examples can be applied in the same manner to other embodiments or examples.

Claims

1. A device for inserting a surgical implant into a bone (4) by impaction, comprising: an impactor (10) for exerting a force on the surgical implant; at least one sensor (12) associated with the impactor (10); a processing unit (30) connected to said sensor (12); an auxiliary tool (20) having a rear end forming an impact surface and a front end cooperating with said surgical implant; Equipped with the sensor (12) is configured to measure a deformation of the impactor (10) and to provide a measurement signal representative of the change in said deformation over time during impact; the processing unit (30) calculates an index representative of a contact level between the surgical implant and the bone (4) based on the time-dependent change in deformation of the impactor (10) during impact; The impactor (10) applies a striking force to the surgical implant via the auxiliary tool (20); The impactor (10) has a striking surface (11a) for striking an impact surface (22), an opposite surface (11b) opposite to the striking surface (11a), and a side surface (11c) extending between the striking surface (11a) and the opposite surface (11b), The at least one sensor (12) is disposed on a side extending between the striking surface (11a) and the opposite surface (11b); The device is characterized in that deformation of the striking surface (11a) and the opposing surface (11b) thereby causes deformation of the sensor (12).

2. 2. The device according to claim 1, characterized in that the processing unit (30) comprises a low pass filter for attenuating frequency components in the measurement signal that are higher than a threshold value that is greater than or equal to 20% and less than or equal to 100% of the resonant frequency of the impactor (10).

3. 3. The device according to claim 1 or 2, characterized in that the processing unit (30) comprises a low-pass filter for attenuating frequency components in the measurement signal that are higher than a threshold value between 1 kHz and 35 kHz, in particular a threshold value between 5 kHz and 20 kHz.

4. The impactor (10) has a front surface (11e) on which a protrusion (9) is formed, 3. A device according to claim 1 or 2, characterized in that the front surface (9a) of the projection (9) forms the striking surface (11a) of the impactor (10), and the sensor (12) is attached to the side surface of the projection (9).

5. A device as described in claim 1 or 2, characterized in that the index is an index (IN1) corresponding to the average of the deformation calculated in a time window of programmable duration positioned in the measurement signal.

6. The index (IN1) is calculated as follows: [0010] A(t) corresponds to the intensity of the measured signal at time t; A1 corresponds to the maximum intensity of the measurement signal, t1 and t2 correspond to the start and end times of the time window, respectively.

6. The device according to claim 5 .

7. The indicator corresponds to a duration of a time window; the start time of the time window is defined as the time corresponding to a first maximum of the measurement signal, 3. The device according to claim 1, wherein the end time of the time window is defined as the time corresponding to a second peak of a maximum of the measurement signal.

8. a warning system (33) connected to said processing unit (30); The device according to claim 1 or 2, characterized in that the warning system (33) interacts with the processing unit (30) to issue a warning signal when the indicator converges to a satisfactory value during a strike or when the indicator exceeds a predetermined threshold value.

9. The impactor (10) is a hammer with a gripping shaft (13) having a striking head (11) at the top, 3. A device according to claim 1 or 2, characterized in that the sensor (12) is attached to the striking head (11) in such a way that a deformation of the striking head (11) causes a deformation of the sensor (12).

10. The striking head (11) has the striking surface (11a), the opposite surface (11b), and the side surface (11c), The side surface (11c) extends substantially parallel to the axial direction of the gripping shaft (13); 10. A device according to claim 9, characterized in that the sensor (12) is arranged in front of one of the lateral sides (11c), between the striking face (11a) and the axis of the gripping shaft (13).

11. Assembly comprising a device according to claim 1 or 2 and a surgical implant, in particular a femoral stem or an acetabular cup (2).

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