WO2021072546A1

WO2021072546A1 - Force measurement device

Info

Publication number: WO2021072546A1
Application number: PCT/CA2020/051388
Authority: WO
Inventors: Linda McLean; Ana Bryn BRENNAN
Original assignee: University Of Ottawa
Priority date: 2019-10-17
Filing date: 2020-10-16
Publication date: 2021-04-22

Abstract

A force measurement device has a moveable probe collet that can receive a probe, such as a cotton swab. When a force is applied to the cotton swab in the moveable probe collet, the moveable probe collet is forced against a spring element which in turn applies a force to a force sensor. The force applied to the force sensor can be displayed, or otherwise captured to allow a doctor, researcher, clinician, etc. to evaluate a patient's pressure pain threshold. Alternatively by using a tuned spring, the device can limit the force applied to the patient such that this force can be standardized among patients or between trials. The force measurement device is made from material that can be sterilized in autoclave.

Description

FORCE MEASUREMENT DEVICE

RELATED APPLICATIONS

[0001] The current application claims priority under the Paris convention to US provisional application number 62/916,349 Filed October 17, 2019, the entire contents of which are incorporated herein by reference for all purposes.

TECHNICAL FIELD

[0002] The current disclosure relates to a medical device for applying a force to an area on a body, and in particular to a sterilizable device with a disposable tip capable of measuring the applied force.

BACKGROUND

[0003] Various medical tests or examinations include evaluating a patient’s pain level, which may include using a finger or probe to apply pressure to an area being examined. While such tests may provide useful information, the inability to consistently apply a known force to the area being probed makes the reproducibility of the tests difficult and so can limit their usefulness.

[0004] Devices such as algometers can measure an amount of force applied to a patient’s skin that causes the patient to report pain. The force applied by the algometer varies according to the force applied by the physician or other healthcare professional carrying out the test.

[0005] In an attempt to improve the ability of a physician or healthcare professional to repeatedly apply the same force to the patient, or possibly different patients, a number of different cylindrical hand-held devices can be provided, with each device having a spring of a different compression rate. By compressing the spring by a specific amount, a known force will be applied at the tip of the device.

[0006] While there are various devices that can measure a pressure or force applied to an area of individual’s body, it would be advantageous to have an additional, alternative and/or improved device capable of measuring a pressure or force applied to an area of an individual’s body. SUMMARY

[0007] In accordance with the present disclosure there is provided a sterilizable force measurement device comprising: an outer housing; a force sensor secured within the outer housing; a moveable probe collet for securing a replaceable probe within the force measurement device; and a spring element within the outer housing located between the moveable probe collet and the force sensor and biasing the moveable probe collet away from the force sensor.

[0008] In a further embodiment of the force measurement device, the moveable probe collet comprises: a moveable plunger secured within the outer housing; and a collet connected to the moveable plunger.

[0009] In a further embodiment of the force measurement device, the moveable probe collet is secured at least partially within the outer housing by a removable top cap.

[0010] In a further embodiment of the force measurement device, the removable top cap is secured to the outer housing by a threaded connection.

[0011] In a further embodiment, the force measurement device further comprises a force transfer plate connected between the spring element and the force sensor.

[0012] In a further embodiment, the force measurement device further comprises a force limiting element for limiting a maximum force applied to the force sensor by the force transfer plate.

[0013] In a further embodiment, the force measurement device further comprises a force sensor holder for removably receiving the force sensor.

[0014] In a further embodiment, the force measurement device further comprises an electrical connector providing an electrical connection to the force sensor.

[0015] In a further embodiment, the force measurement device further comprises a feedback mechanism providing feedback to a user about an applied force measured by the force sensor. [0016] In a further embodiment of the force measurement device, the feedback mechanism comprises one or more of: a display; a light emitting diode (LED); a speaker; and a haptic feedback device.

[0017] In a further embodiment, the force measurement device further comprises a wireless communication radio.

[0018] In a further embodiment, the force measurement device further comprises a travel sensor for measuring a displacement distance of the moveable probe collet.

[0019] In a further embodiment of the force measurement device, the outer housing, moveable probe collet and spring element are formed from surgical stainless steel or anodized aluminum.

[0020] In accordance with the present disclosure there is further provided a force measurement system comprising: a force measurement device according to any one of claims 1 to 13; and a feedback device for receiving force measurements from the force measurement device.

[0021] In a further embodiment of the force measurement system, the force measurement device and the feedback device communicate wirelessly.

[0022] In a further embodiment of the force measurement system, the force measurement device and the feedback device communicate over a wired connection.

[0023] In a further embodiment of the force measurement system, the feedback device is configured to present a user interface to a patient to allow the patient to indicate when an applied force crosses a pain threshold.

[0024] In a further embodiment, the force measurement system further comprises a patient feedback device communicatively coupled to the feedback device to allow the patient to indicate when an applied force crosses a pain threshold.

[0025] In accordance with the present disclosure there is further provided a use of a force measurement device according to any one of claims 1 to 13 in evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity. [0026] In accordance with the present disclosure there is further provided a use of a force measurement system according to any one of claims 14 to 18 in evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity.

[0027] In accordance with the present disclosure there is further provided a method of evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity comprising: applying a force to an area of the patient using a force measurement device as described above; receiving an indication from the patient of the patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity; and recording an indication of a force applied to the area by the force measurement device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Features, aspects and advantages of the present disclosure will become better understood with regard to the following description and accompanying drawings in which:

[0029] FIG. 1 depicts an assembled sterilizable force measurement device;

[0030] FIG. 2A depicts a front perspective exploded view of the sterilizable force measurement device of FIG. 1 ;

[0031] FIG. 2B depicts a rear perspective exploded view of the sterilizable force measurement device of FIG. 1 ;

[0032]

[0033] FIG. 3 depicts a cross sectional view of the sterilizable force measurement device of FIG. 1;

[0034] FIG. 4 depicts a cross sectional view of a further sterilizable force measurement device;

[0035] FIG. 5 depicts a force vs time measurement using a sterilizable force measurement device;

[0036] FIG. 6 depicts a further force vs time measurement using a sterilizable force measurement device; [0037] FIG. 7 depicts a sterilizable force measurement device incorporating a feedback device;

[0038] FIG. 8 depicts a sterilizable force measurement device incorporating a patient feedback device;

[0039] FIG. 9 depicts a sterilizable force measurement device incorporating a further patient feedback device;

[0040] FIG. 10 depicts a force graph of the force applied in determining the PPT for a participant; and

[0041] FIG. 11 depicts a force graph of the force applied in determining the TS for a participant.

DETAILED DESCRIPTION

[0042] The sterilizable force measurement device described further herein may be used in administering a cotton-swab test. The cotton-swab test is a standard diagnostic test for vulvovaginal pain disorders, and it is typically conducted when patients present with provoked introital pain. The cotton-swab test consists of the palpation of several genital regions, in particular, the vulvar vestibule, with a cotton-tipped applicator. Clinically, the cotton-swab test is quick to administer and it is highly useful for diagnostic purposes. Flowever, different healthcare professionals apply different amounts of force during the cotton-swab test, and even the same professional may vary in terms of their applied force. This approach has proven useful for research studies, and although the cotton-swab test is useful for confirming an initial diagnosis, it is not a highly standardized method of assessment; therefore, it has limitations in terms of its clinical applicability to monitor changes over time or to evaluate changes in pain processing such as those which occur in chronic pain conditions.

[0043] In an effort to standardize a version of the cotton-swab test for research purposes, Pukall et al. (2004, 2007) developed a pressure-pain threshold device (i.e. , a vulvalgesiometer) that exerts predetermined force levels via a spring-based system, primarily consisting of a series of syringes which house springs of different constants, and removable and disposable cotton-swabs. In the initial validation study, women with PVD reported experiencing pain at the posterior portion of the vestibule at, on average, 16.4 grams (versus 285.7 grams in the control group). A few years later, Pukall et al. simplified the design of the vulvalgesiometer and increased the number of pressure levels to 26 (versus 24 with the original set) (Pukall et al., 2007). Results indicated high inter-rater reliability between two testers, and a significant between-group (PVD and pain-free control women) difference.

These vulvalgesiometers have been used in a variety of studies by Pukall and her collaborators, to examine treatment outcomes. Although valuable in a research setting, Pukall’s vulvalgesiometers are too cumbersome for use in a clinical practice since the user has to switch among separate devices to apply different pressures. Further, Pukall’s vulvalgesiometer is problematic in terms of cleaning. While the cotton-swab tip is replaced between patients to limit the transmission of infection, because of the proximity with which the device is held to the perineum, and the need for the user to manipulate the device location during use, which often requires touching the patients genitals, it is important to ensure that the device can be disinfected between uses as viruses such as herpes, MRSA, Hepatitis B, HPV etc. may otherwise be transmitted from one patient to the next.

[0044] The sterilizable force measurement device described further herein allows healthcare professionals such as a doctor, technician, researcher or clinician to apply a known force to an area on an individual’s body. The device comprises a moveable probe collet that allows a removable probe such as a cotton swab to be fixed within the collet. When a force is applied to the cotton swab, the moveable probe collet moves within an outer housing. The moveable probe collet compresses a spring against a force sensor that measures the force applied by the probe. The force measurement device can be sterilized in an autoclave, allowing the measurement device to be effectively used in medical applications.

[0045] A single compact measurement device can be used to apply a full range of forces, determined through the combination of the spring constant and the force sensor range, so the user does not have to switch among different devices to increase the force delivered in order to determine a pressure-pain threshold. The measurement device provides an objective measure of the force applied in order to determine pain threshold or tolerance and the force can be digitally displayed to the user in real time. Alternatively the measurement device can deliver a pre-set force in order to standardize clinical assessment using a cotton swab test, or to ensure the force delivered remains constant when evaluating changes in pain processing such as the temporal summation of pain. Further, the measurement device may be easily disinfected using high level disinfection, including for example autoclaving or gas sterilization after the disposable tip is disposed of.

[0046] As described further herein, the measurement device provides a simple design that can be easily sterilized between uses. The measurement device is compact and may use a single force sensor to evaluate pain using a wide range of applied forces. The devices may be used by doctors, nurses, researchers, clinicians, physiotherapists, dentists, dental hygienists, etc. The device may be of use to gynecologists and physiotherapists working in the area of gynecology. Further, the device may be of use to dentists and dental surgeons as well as other medical fields.

[0047] An embodiment of a sterilizable force measurement device is described in further detail below with particular reference to FIGs. 1 - 3. FIG. 1 depicts an assembled force measurement device. FIG. 2A depicts an exploded view of the force measurement device of FIG. 1. FIG. 2B depicts a further exploded view of the force measurement device of FIG. 1 , although the electrical connectors have been omitted for clarity. FIG. 3 depicts a cross sectional view of the force measurement device of FIG. 1.

[0048] The force measurement device 100 comprises an outer housing 102. The outer housing 102 may be generally cylindrical in shape as depicted, although other shapes are possible. A top cap 104 may be used to secure a moveable probe collet 106 at least partially within the outer housing 102. The moveable probe collet 106 can receive a probe 108 such as a cotton swab or other disposable tip. A rear cap 110 can be secured to the rear of the housing to enclose the components. An electrical connector 112 can be connected to the device, which may allow the device to be connected to other computing devices. The electrical connector 112 may provide a wired connection as depicted or may provide a wireless connection for transmitting the measurement information to other devices.

[0049] The force measurement device 100 comprises a spring element 114 that is located between the moveable probe collect 106 and a force sensor 116 for measuring the force applied by the probe tip 108. The force sensor may be a miniature load cell such as an S410 Miniature Load Cell provided by SMD (Strain Measurement Devices), although other force sensors may be used. The moveable probe collet 106 moves within the housing 102 and compresses the spring element 114 against the force sensor, applying a corresponding force on the force sensor 116. The force sensor 116 may be removably received within a force sensor holder plate 118 that has a recess for receiving the force sensor. Although force sensors exist that can be autoclaved, typically they are only able to withstand a certain number of cycles through the autoclave and as such by removing the force sensor 116 before autoclaving the other components of the device 100 the life of the sensor may be extended. When the device 100 is assembled, the force sensor holder plate 118 can be seated against a bottom sensor plate 120. Part of an electrical connector 122 can be received at least partially within the bottom sensor plate. The electrical connector 122 may be for example a mini DIN 6 pin female sensor.

[0050] As described above, the moveable probe collet 106 receives a probe and is moveable within the housing 102. The moveable probe collet 106 may be provided by a single element or by multiple elements. As depicted, the moveable probe collet 106 may comprise a probe collet 106a that receives the probe 108, and a moveable plunger 106b that holds the probe collet 106a. When a force is applied to the probe 108, the moveable probe collet 106 slides within the housing and causes the spring element 114 to compress and exert a force on the force sensor 118. The spring element 114 may be connected to a force transfer plate 124 to allow the spring force to be transferred to the force sensor 116. In order to prevent overloading of the force sensor 116, an overload protection element 126 can be used to prevent movement of the moveable probe collet 106 past a safe point at which the exerted force by the compressed spring does not exceed the maximum limit of the force sensor. For example, the overload protection element 126 may comprise a projection or profile that prevents the moveable probe collet 106 from moving further than a maximum displacement amount. Although the overload protection element 126 may prevent the force applied to the force sensor 116 from exceeding a maximum value, it does not limit the force applied by the probe 108 on the patient’s skin.

[0051] As described above, the force measurement device 100 may comprise a cotton swab or other tip 108 that is sterile and/or disposable which can be inserted into a moveable collet 106 at the distal end of the device 100. When the tip of the cotton swab is pressed against the patient, forces are measured by the force sensor 116 which can be fixed within a holder 118 located inside the device casing 102. The force sensor holder 118 ensures that the force sensor 116 does not rotate inside the device possibly putting stress on the connectors. The force sensor 116 may be fixed between two force sensor plates 124, 120 within the device casing with caps on the top 104 and the bottom 110. [0052] When in use, the motion of the cotton swab 108 passing through the hole in the top cap 104 of the device presses the plunger 106b, which in turn, compresses the spring 114 within the casing 102. Different springs may be provided within the device to provide different forces. One option, used to determine patient’s pressure-pain threshold, is to use a spring with parameters that result in applied forces ranging over a defined range such as from ON to 100N. Alternatively, a different spring may be used that is tuned to provide noticeable deflection of the probe 108, of for example 2 mm, at a required or desired force, such as 5N. When the desired force is met the user may be alerted by a feedback mechanism such as a display, LED, sound, or haptic feedback. Additionally, if the device is connected to another computing device, such as a computer, laptop, smart phone, tablet etc., feedback may be displayed to the user on the computing device.

[0053] In prototypes of the force measurement device, two such springs were used, one that delivers 0.245N and one that delivers 3.69 N of force. These specifications allow the clinician to apply a repeatable force when evaluating pressure pain thresholds, levels or sensitivities reported by patients during repeated examinations in order to evaluate differences in pain between locations or changes in pain over time, for example, after some intervention.

[0054] Other features of the design include overload protection 126 built into the housing, between the spring 114 and the force sensor 116, which may be a hard limit on the amount of compression that the spring can undergo. This protects the sensor from damage. Further, the spring, housed within the casing, and between the top spring holder 128 and the force sensor plate 124 cannot buckle or rotate which would cause damage during repeated use.

[0055] As depicted in FIGs. 1 - 3, the force sensor is interfaced with a 6-pin mini din (female) which may connect the device via hard wire (male) to a PC in order to stream data. In addition to, or as an alternative to, the wired connection, the device may include a wireless radio, such as a Bluetooth radio, for wirelessly connecting the device to other devices such as a tablet or phone. Additionally, or alternatively, the device may have an LED display that indicates the maximum force applied during each trial right on the device itself, and which would be reset between trials.

[0056] FIG. 4 depicts a cross sectional view of a further sterilizable force measurement device. The force measurement device 400 is similar to the force measurement device 10 described above with regard to FIGs. 1 - 3 but is a wireless device. The device 400 comprises an outer housing 402 and top cap 104 that secures a moveable collet comprising a probe collet 106a and moveable plunger 106b to the outer housing 402. A swab or probe 108 can be secured within the probe collet 106 and extends out of the device 400. A spring 114 is located within the outer housing 402 between the moveable plunger 106b and a force sensor 116. The outer housing 402 may be extended in order to provide housing for electronics 404 and a battery 406. The electronics 404 may be connected to both the force sensor 116 for capturing the data from the force sensor and can provide an interface to external devices for accessing the collected data, possibly in real time for visualization on an external display, or for downloading after a test. The electronics may include a controller, microcontroller, processor or similar computing device 408 that can be configured, for example by executing instructions stored in memory (not depicted), to provide functionality such as measurement, display or feedback as well as interfacing with other devices. The electronics may further include one or more communication radios 410 providing a wireless interface for connecting with other devices. The wireless communication may be provided by, for example, a Wi-Fi ™ interface, a Bluetooth ™ interface, a ZigBee ™ interface, a cellular interface, or other suitable wireless communication interface. The electronics may further include charging circuitry 412 for charging the battery. Additionally, the device 400 may include one or more output devices, depicted as three LEDs 414 located at an end of the device that may be used to provide user feedback, such as when the device 400 is on, a set force is applied, a maximum force is applied, etc. Although depicted as individual LEDs other output devices include a display, speaker, or haptic feedback device may be used. As will be appreciated, the device 400 may function in a similar manner as the device described above with reference to FIG.s 1 - 3, however the functionality may use a wireless interface for providing the measured force information to other connected devices.

[0057] The device components may be suitable for sterilizing by an autoclave. For example the components, other than the force sensor and the electrical connector or electronics, may be cast in surgical stainless steel or anodized aluminum such that it can be autoclaved or otherwise sterilized. An SMD S410 force sensor itself is rated to be autoclaved up to 100 times without damage, however in normal use, the device can be disassembled and the force sensor, and other electronics and/or batteries, removed prior to autoclaving so that the sensor can last much longer, according to manufacturer’s specifications. Accidentally forgetting to remove the sensor from the device would not cause a problem unless this is done more than the rated value of 100 times.

[0058] Although not depicted in FIGs. 1 - 4, the device may include an additional sensor for measuring a distance travelled by the probe. The additional displacement sensor may be used to provide additional functionality such as testing the stiffness of the skin or underlying tissues by measuring a deflection amount resulting from the force applied.

[0059] FIG. 5 depicts a force vs time measurement using a force measurement device. The graph 500 shows a gradual increase in force being applied through the sensor that would be used to determine a patient’s pressure pain threshold, tolerance, and or sensitivity. The user applied force manually at a fairly constant, increasing rate between 2s and 8s. There is a gradual increase 502 in the force applied through the cotton swab (and measured by the sensor) up to the force limit 504 of the device (here the maximum force of the sensor is not reached). In clinical use, an LED display or a display on a smartphone or tablet, which may be connected via Bluetooth, could show the highest force reached before the user stops applying force (i.e. the point at which the patient first reports pain (pressure pain threshold) or, in some applications, the point at which the patient can no longer tolerate increases in force (pressure pain tolerance).

[0060] FIG. 6 depicts a further force vs time measurement using a force measurement device. The graph 600 shows an initial force (220g) being applied at point 602. At point 604, the user began applying increasing force at a constant rate between about 2s and 3.8s. There is a gradual increase in the force applied through the cotton swab (and measured by the sensor) up to the force limit of the device at point 606, which in the test was tuned to 356g. While the user continues to apply more force through the device, after the limit of 356g is reached, there is no increase in the force being applied through the cotton swab tip as it is being limited to 356g until the spring is fully compressed. Accordingly at section 608, the applied force is generally constant. Although generally constant, the force signal may be filtered to filter out slight changes. Once the spring is fully compressed, the applied force may increase as shown at point 610 as the spring no longer dampens the applied force. The user can feel when the spring is no longer damping the force once the spring is fully compressed (i.e. 3.8s) but in clinic, the user would not continue to increase the force applied once the plateau is reached. In clinical use, an LED light would indicate to the user that the pre-determ ined force level has been reached and the user would stop applying force at that point.

[0061] FIG. 7 depicts a force measurement system incorporating a feedback device. The system 700 comprises a device 702, which may be a force measuring device as described above. A doctor or other user 704 may use the device to apply a force to the patient 706. As depicted, the measuring device 702 may be connected, either wirelessly or by wired connection, to a feedback device 708 depicted as a tablet. The feedback device may be configured to display a user interface 710 presenting the measured forces to the doctor 704.

It will be appreciated that the user interface may provide additional functionality to the user such as entering additional patient information such as a described pain level as well as presenting force information.

[0062] FIG. 8 depicts a force measurement system incorporating a feedback device. The system 800 is similar to the system 700 and as such only the differences will be described. The system 800 provides a patient feedback device 808 which provides a user interface 810 to the patient for providing an indication when the applied pressure crosses a pain threshold. When the patient indicates that the applied force should be stopped, the patient feedback device 808 can determine the force that was being applied and record it for presentation to the patient and or doctor 904. The patient feedback device 808 can be synchronized with the force measurements of the measurement device so that the force that was being applied when the user indicates the pain crossing a threshold by operating the patient feedback device, can be determined, even if the doctor or operator subsequently exceeds the applied force.

[0063] FIG. 9 depicts a force measurement system incorporating a further patient feedback device. The system 900 is similar to the systems 700 and 800 described above. However, rather than combining the feedback device 708 with a patient feedback device 808, the system 900 includes both a feedback device as described with reference to FIG. 7 as well as a separate patient feedback device 912 for providing an indication when the test should be stopped. The patient feedback device 912 may be a simple switch or button that the patient holds and operates when it is desired to stop the test, for example as a result of the pressure applied crossing the patient’s pain threshold. The patient feedback device 912 may be connected to the feedback device 708 by a wired or wireless connection. Additionally or alternatively, the patient feedback device 912 may connect directly to the force measurement device 602 either by a wired or wireless connection.

[0064] The force measurement devices described above may be used in various tests including, for example in cotton swab tests used in assessing pain thresholds in Provoked vestibulodynia (PVD). Advantageously, the current device can provide repeatable and reliable measurements. The force measurement device was used to determine between-day test- retest reliability of pressure pain threshold (PPT) and temporal summation of pain (TS) measured at the vulvar vestibule in subject with and without symptoms consistent with PVD.

[0065] PVD is a chronic pain condition characterized by severe sharp and/or burning pain at the vulvar vestibule when pressure is applied to this area. Although it affects roughly one in five women, and has a negative impact on quality of life for approximately half of them, PVD remains poorly understood. The literature suggests that women with PVD have enhanced pain sensitivity, likely due, at least in part, to changes in central nervous system (CNS)- mediated pain processing, leading to allodynia (pain is perceived in response to a normally non-painful stimulus) and hyperalgesia (lower thresholds for pain sensitivity and tolerance). Indeed, there are limited standards for the evaluation of CNS-mediated sensitization in general, which has implications for conditions such as PVD. The cotton swab test is recommended as a standard assessment of pain sensitivity in women with PVD. Yet this test is poorly controlled, with methods varying based on clinician preference and experience: some use lubrication while others don’t, and variable amounts of pressure are applied. In the literature, pressure pain threshold (PPT) and temporal summation of pain (TS) are two quantitative methods to evaluate allodynia and hyperalgesia.

[0066] In determining the between-day test-retest reliability of PPT and TS measured at the vulvar vestibule using a force measurement device as described above, females over 18 years of age, both with and without symptoms consistent with PVD, were recruited from the local community. Exclusion criteria were pregnancy, menopause, and diagnosed gynecologic conditions (e.g., pelvic organ prolapse, urinary incontinence, vaginal infection). Participants attended two laboratory-based assessments within one week following the start of their menstrual cycle. At each of the two assessments, PPT and TS were determined using the force measurement device. The force measurement device engages a cotton swab into a collet. When the tip of the cotton swab is pressed, it compresses a spring interfaced with a force sensor which is displayed, allowing the user to see, in real time, the force being applied during testing. Using this force measurement device, PPT was defined as the force (in grams) at which women first reported pain when the cotton-swab was applied at the 6 o’clock position of the vestibule. For TS, the force determined as the PPT was applied at the same location ten times (approximately one per second). Participants rated their pain on the first and last application of this force on a 0 (no pain at all) to 10 (worst pain ever) scale. TS was defined as the difference in pain rating between the last and first application.

[0067] FIG. 10 depicts a force graph of the force applied in determining the PPT for a participant. As depicted, the pressure at which the patient first reported pain, labelled as PPT in FIG. 10, was measured at 365.31 g.

[0068] FIG. 11 depicts a force graph of the force applied in determining the TS for a participant. As depicted three repetitions of the PPT force delivered at the vulvar vestibule were applied during assessment of TS for the same participant. The horizontal line indicates the target force of 365g.

[0069] Table 1 shows the outcome of the test. Twenty-four women participated; 14 reported no history of vulvar pain, while 10 reported symptoms of vulvar pain including PVD and deep dyspareunia. As can be seen from Table 1, PPT measurement demonstrated good reproducibility and TS demonstrated acceptable reproducibility using the force measurement device described herein. In Table 1 , SD is for standard deviation, ICC is for intra-class correlation coefficient, Cl is for confidence interval, SEM is for standard error of measurement and MDC is for minimal detectable change.

Table 1. Main outcome measures

[0070] Embodiments of a sterilizable force measurement device with disposable tips has been described above that uses a spring element within the outer housing to bias a moveable collet for holding a disposable collet away from a force sensor. The spring element above is depicted as a traditional wound spring, however the spring element may be provided by any suitable element that is resiliently deformable. The spring element can help in providing a set force level. The force applied does not need to be limited by the spring element. The force applied may be controlled by the user in coordination with real time feedback from, for example, an output of the force measured by the sensor, and/or directly from the patient. The resistance to movement of the collet provide by the spring element may give users feedback as to the force being applied. It is possible to eliminate the spring element and have the collet for the disposable probe tip contact the force sensor directly. A feedback device may provide feedback to the user on the force applied as determined by the force sensor. The feedback device may take various forms including for example the spring element described above providing tactile feedback, a buzzer or speaker, LEDs, a display, an eccentric rotating mass actuator, or an interface to external devices for providing the feedback such as on a display of an external computer.

[0071] It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention. Although specific embodiments are described herein, it will be appreciated that modifications may be made to the embodiments without departing from the scope of the current teachings. Accordingly, the scope of the invention should not be limited by the specific embodiments set forth, but should be given the broadest interpretation consistent with the teachings of the description as a whole.

Claims

WHAT IS CLAIMED IS:

1. A sterilizable force measurement device comprising: an outer housing; a force sensor secured within the outer housing; a moveable probe collet for securing a replaceable probe within the force measurement device; and a spring element within the outer housing located between the moveable probe collet and the force sensor and biasing the moveable probe collet away from the force sensor.

2. The force measurement device of claim 1 , wherein the moveable probe collet comprises: a moveable plunger secured within the outer housing; and a collet connected to the moveable plunger.

3. The force measurement device of claim 1 or 2, wherein the moveable probe collet is secured at least partially within the outer housing by a removable top cap.

4. The force measurement device of claim 3, wherein the removable top cap is secured to the outer housing by a threaded connection.

5. The force measurement device of any one of claims 1 to 4, further comprising a force transfer plate connected between the spring element and the force sensor.

6. The force measurement device of claim 5, further comprising a force limiting element for limiting a maximum force applied to the force sensor by the force transfer plate.

7. The force measurement device of any one of claims 1 to 6, further comprising a force sensor holder for removably receiving the force sensor.

8. The force measurement device of any one of claims 1 to 7, further comprising an electrical connector providing an electrical connection to the force sensor.

9. The force measurement device of any one of claims 1 to 8, further comprising a feedback mechanism providing feedback to a user about an applied force measured by the force sensor.

10. The force measurement device of claim 9, wherein the feedback mechanism comprises one or more of: a display; a light emitting diode (LED); a speaker; and a haptic feedback device.

11. The force measurement device of any one of claims 1 to 10, further comprising a wireless communication radio.

12. The force measurement device of any one of claims 1 to 11 , further comprising a travel sensor for measuring a displacement distance of the moveable probe collet.

13. The force measurement device of any one of claims 1 to 12, wherein the outer housing, moveable probe collet and spring element are formed from surgical stainless steel or anodized aluminum.

14. A force measurement system comprising: a force measurement device according to any one of claims 1 to 13; and a feedback device for receiving pressure measurements from the force measurement device.

15. The force measurement system of claim 14, wherein the force measurement device and the feedback device communicate wirelessly.

16. The force measurement system of claim 14 wherein the force measurement device and the feedback device communicate over a wired connection.

17. The force measurement system of any one of claims 14 to 16, wherein the feedback device is configured to present a user interface to a patient to allow the patient to indicate when an applied force crosses a pain threshold.

18. The force measurement system of any one of claims 14 to 17, further comprising a patient feedback device communicatively coupled to the feedback device to allow the patient to indicate when an applied force crosses a pain threshold.

19. Use of a force measurement device according to any one of claims 1 to 13 in evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity.

20. Use of a force measurement system according to any one of claims 14 to 18 in evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity.

21. A method of evaluating a patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity comprising: applying a force to an area of the patient using a force measurement device according to any one of claims 1 to 13; receiving an indication from the patient of the patient’s pressure pain threshold, pressure pain tolerance, or pressure pain sensitivity; and recording an indication of a force applied to the area by the force measurement device.