Bone Fixation Monitoring System

Abstract

The present invention provides a system for monitoring ossification of an internally fixed bone fracture in a subject, comprising an implantable fixation device and an external wireless reader operable to transmit data regarding the relative load experienced by a bone plate across the fracture to a data server, where a trend in the increased bone support provided by the bone plate can be visualized. The implantable fixation device comprises a primary load sensor and a reference load sensor, wherein the load value from the reference load sensor can be used to normalize the load value from the primary load sensor. The external wireless reader is in wireless communication with the implantable fixation device and operable to receive a signal indicative of the load from each load sensor and to energize each load sensor via inductive charging.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent No. 63 / 054,557, filed on July 21, 2020, which is incorporated by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to systems and methods for monitoring the healing / ossification of fractured bones. Background Art

[0004] Conventional bone fixation system comprises the bone plate with screw hole, and described screw hole receives fixing member, such as screw, and described screw is configured to be attached to following bone, and described following bone comprises at least a pair of bone segments separated by bone gap.Bone gap can be the fracture formed by traumatic event, osteotomy, or can be the result of joint debridement of two discrete bones to be joined in arthrodesis.Therefore, bone plate can be attached to the bone on the opposite side of bone gap via bone screw, to promote the union (for example, the healing of fracture or the ossification of joint) of bone segment.Bone fixation system can also comprise temporary Kirschner wire (temporary Kirschner wires) (K-wire), this temporary Kirschner wire is temporarily inserted in the hole of bone fixation plate and inserts in following bone segment, to determine the appropriate length, rotation and alignment of bone segment before permanent plate fixation.Once bone fixation plate is suitably positioned, then permanent bone screw can be inserted in one or more bone screw holes on the opposite side of bone gap, and attached to following bone. Summary of the Invention

[0005] A system for monitoring ossification of an internally fixed bone fracture in a subject includes an implantable fixation device and an external wireless reader operable to transmit data regarding the relative load experienced by a bone plate across the fracture to a data server, where a trend in the increased bone support provided by the bone plate can be visualized.

[0006] The implantable fixation device includes a main load sensor and a reference load sensor, both of which are in direct physical contact with the bone plate. The main load sensor is disposed at a first position on the bone plate, the first position being operable to be positioned directly adjacent to the fracture. The main load sensor may generally include: a first strain sensor operable to monitor the amount of strain (main strain) at the first position of the bone plate; and a communication circuit operable to transmit a first wireless signal indicating the amount of main strain. The reference load sensor is disposed at a second position on the bone plate spaced apart from the first position. The reference load sensor may include a second strain sensor operable to monitor the amount of strain (reference strain) at a second position in the bone plate; and a communication circuit operable to transmit a second wireless signal indicating the amount of reference strain.

[0007] The external wireless reader may receive the first wireless signal and the second wireless signal via an antenna, determine a relative amount of support provided by the bone plate due to the fracture using the received indication of the principal strain and the received indication of the reference strain, and transmit the determined relative amount of support to a data server via a wireless communication network using a wireless communication radio. In one configuration, the relative amount of support provided by the bone plate due to the fracture may be calculated by dividing the principal strain value by the reference strain value.

[0008] Using these devices, a method for collecting bone ossification data from an implantable smart fixation device placed in a subject's body can begin by energizing an external antenna equipped with an external wireless reader to generate an alternating magnetic field and inductively energizing each of a primary load sensor and a reference load sensor. The external wireless reader can then receive a wireless data signal from each load sensor, indicating the amount of strain experienced by the bone plate at that corresponding location.

[0009] Furthermore, a method for monitoring bone fracture ossification from multiple subjects via a data server may begin by receiving a plurality of ossification data points from the multiple subjects via a wireless communication network. Each data point represents a measurement taken from a smart fixation device fixed to a bone of the subject across the fracture. The measurement represents the amount of load carried by the fixation device across the fracture relative to the amount of load carried by the fixation device in dense bone. The method also includes storing each of the plurality of data points in non-volatile memory in conjunction with the date and time at which the measurement was taken and a patient identifier indicating the source of the measurement. The data server may then provide a physician interface to graphically display the changes in the measurements from each of the plurality of different subjects over time.

[0010] In one configuration, a data server may maintain a machine learning prediction model that generates a predicted patient-specific healing trajectory for each subject. The patient-specific healing trajectory includes a predicted trajectory and a confidence interval that represents the likely healing progression that begins at the time of bone fixation. The method also includes overlaying a plurality of data points or an empirical trend line for the subject on a graphical representation of the predicted patient-specific healing trajectory within a physician interface. The machine learning prediction model is improved using at least a subset of the received plurality of data points and a plurality of secondary factors, the plurality of secondary factors including at least two of the following: the nature and location of the fracture, the subject's height, weight, age, sex, metabolic profile, blood pressure, preexisting conditions, complex risk factors, or comorbidities.

[0011] The data server can also calculate a forward-looking healing trajectory for each subject, extending forward in time from the subject's most recently collected data point. This forward-looking healing trajectory can also be superimposed on a graphical representation of the predicted patient-specific healing trajectory. If either the data point or the forward-looking healing trajectory is outside the confidence interval, the data server can provide a warning via the physician interface.

[0012] As used herein, the terms "a," "an," "the," "at least one," and "one or more" are used interchangeably to indicate that there is at least one of an item; unless the context clearly indicates otherwise, there can be a plurality of such items. All numerical values for parameters (e.g., quantities or conditions) in this specification (including the appended claims) are to be understood as being modified in all instances by the term "about," whether or not "about" actually precedes the numerical value. "About" indicates that the numerical value allows for some slight imprecision (some approach to exactness of the value; approximately or reasonably close to the value; close). If the imprecision provided by "about" is not understood in this ordinary sense in the art, then as used herein, "about" indicates variations that can at least result from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values within the entire range and further divided ranges. Therefore, each value within the range and the endpoints of the range are disclosed as separate embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of a system for monitoring fracture healing.

[0014] Figure 2 is a schematic diagram of an implantable smart fixation device for surgically repairing a fractured bone.

[0015] Figure 3 is a schematic side perspective view of an external wireless reader for wirelessly connecting to an implantable smart fixation device.

[0016] Figure 4 Schematic diagram of a portable computing device that wirelessly communicates with an implantable smart fixation device via an external antenna.

[0017] Figure 5 During the measurement, Figure 3-Figure 4 Schematic diagram of a progression of user interface display screens displayed to a patient by a portable computing device shown in .

[0018] Figure 6 is a schematic diagram of a method for collecting and aggregating patient healing data from an implantable smart fixation device.

[0019] Figure 7 is a schematic representation of a patient-specific trend line plotted through multiple load ratio data points acquired over time.

[0020] Figure 8 is a schematic diagram of a physician interface that can display patient-specific healing trend lines constructed for one or more patients.

[0021] Figure 9 is a schematic side perspective view of an external wireless reader secured to a patient's upper thigh. DETAILED DESCRIPTION

[0022] The present technology as a whole relates to a system and device that enables physicians to better understand the recovery and healing process of internally fixed fractures compared to more traditional forms of treatment. More specifically, the present design provides for regular (even daily) testing of fracture healing progress while providing the convenience of performing the test outside the confines of a clinic or examination room. By using connected hardware and a centralized data management system, orthopedic surgeons can obtain remote access to diagnostic data obtained directly from the internal fixation system. Using this quantitative data, physicians can be better prepared to provide consultations to patients, such as in a virtual, telemedicine-based manner. In this way, the present technology can make remote monitoring a required standard of care for monitoring the healing progress of internally fixed fractures.

[0023] Referring to the drawings, wherein like reference numerals are used to designate similar or identical parts throughout the various views, Figure 1 Schematically illustrated is a system 10 for remotely monitoring ossification / healing of a fracture or other bone joint that is internally fixed (eg, with a bone plate 12 and a plurality of permanent fixation members such as bone screws 14). Figure 2). Generally speaking, the system 10 includes a data server 20 and / or a cloud computing system 22 that is operable to receive patient data 24 from one or more patient monitoring systems 26 over a wireless communication network 28. The data server 20 / cloud computing system 22 can store the received patient data 24 in an associated non-volatile memory / database 30 and can visually present the data to a medical professional 32 via a hosted physician interface 34. The patient monitoring system 26 can be configured to periodically monitor the amount of load carried by the bone plate 12 across the fracture throughout the healing process. This load measurement can be normalized for the load carried by the bone plate 12 away from the fracture and can be periodically transmitted from the patient monitoring system 26 to the data server 20, where it is aggregated with other patient data 24 to highlight trends in fracture healing.

[0024] Continue to see Figure 1 The data server 20 can be implemented as one or more high-speed server computers or large computing devices capable of handling batch data processing and data visualization tasks. On the other hand, the cloud computing system 22 can operate as middleware for IoT (Internet of Things), WoT (Internet of Things), and / or M2M (Machine to Machine) services, thereby connecting a variety of heterogeneous electronic devices to a service-oriented architecture (SOA) via a data network. As an example, the cloud computing system 22 can be implemented as a middleware node to provide different functions for dynamically loading heterogeneous devices, multiplexing data from each of these devices, and routing this data through reconfigurable processing logic for processing and transmission to one or more target applications. The wireless communication network 28 can be any available type of network, including a combination of public distributed computing networks (e.g., the Internet) and secure private networks (e.g., local area networks, wide area networks, virtual private networks). It can also include wireless and wired transmission systems (e.g., satellite, cellular networks, terrestrial networks, etc.). Most, if not all, data transaction functions may be conducted, for example, over a wireless network, such as a wireless local area network (WLAN) or a cellular data network operating, for example, according to a 4G, 5G, LTE, LPWAN, LTE-M, CAT-M1, or NB-IoT protocol.

[0025] like Figure 1As further shown in FIG, the patient monitoring system 26 generally includes an implantable smart fixture 40 and an external (external) wireless reader 42 for connecting to the smart fixture 40. The external wireless reader 42 is configured to wirelessly receive data from the smart fixture 40 through the patient's skin, for example, via a radio frequency (RF) data communication device (such as RFID or NFC). In at least some embodiments, the external wireless reader 42 can also be configured to wirelessly provide a power source to the smart fixture 40, which can enable the fixture 40 to operate without an internal battery.

[0026] See also Figure 2 , the implantable smart fixation device 40 may include a rigid bone plate 12 that is configured to be fixed across and to opposite sides of the fracture 50 using a plurality of permanent fixation members (such as bone screws 14). The bone plate 12 may be formed of any suitable implantable material, such as, but not limited to, a metal (e.g., a titanium alloy) or a polymer, such as polyetheretherketone (PEEK). Although the present disclosure generally discusses the use of remote monitoring technology in conjunction with a bone plate fixation device, the technology may also be used with other rigid fixation members, such as implantable rods, pedicle screws, intervertebral implants, and the like.

[0027] The smart fixation device 40 can generally include at least one primary load sensor 52 operable to sense the load carried by the plate at the fracture 50. As the fracture heals / ossifies, the amount of load carried by the plate 12 at the fracture 50 should decrease (i.e., while the load-bearing capacity of the healing bone correspondingly increases). In many embodiments, the smart fixation device can also include at least one reference load sensor 54 operable to sense the load carried by the plate 12 at a location spaced apart from the fracture. The reference load sensor 54 can generally serve as a baseline for the amount of load carried by the plate 12 adjacent to healthy or unfractured bone.

[0028] In one configuration, each load sensor 52, 54 may include one or more strain gauges 60 having electrical properties that vary in a predetermined manner depending on the amount of strain experienced by the strain gauge / plate at that location. Examples of suitable strain gauges include resistive strain gauges, capacitive strain gauges, piezoelectric materials, electroactive polymer materials, and the like. Each strain gauge 60 may maintain firm, rigid contact with the plate 12 so that the strain gauge also experiences any bending or flexing of the plate. As is well known, strain and load are directly proportional, so measuring strain is one way to monitor the load carried by the plate.

[0029] Continue to see Figure 2The smart fixture 40 also includes a communication circuit 62 electrically coupled to each strain gauge 60 and an antenna 64 in communication with the communication circuit 62. The communication circuit 62 is configured to receive measurements from the strain gauges 60 and provide the measurements to the antenna 64 in a form suitable for wireless transmission. The communication circuit 62 may include a wireless transmitter or transponder that receives the measurements from the strain gauges 60 and prepares the measurements for wireless transmission. For example, the communication circuit 62 may include processing components such as, but not limited to, one or more of the following: (i) a memory configured to store the measurements, (ii) a digital-to-analog converter configured to convert the measurements into an analog format, (iii) a radio frequency (RF) modulator configured to modulate the measurements, (iv) an error correction encoder configured to encode the measurements, and other processing consistent with the wireless technology employed by the system.

[0030] In one example, the communication circuit 62 can be configured as a passive radio frequency identification (RFID) transponder. Alternatively, the communication circuit 62 can be configured using any other wireless communication technology suitable for communicating through the skin, such as (but not limited to) battery-assisted passive RFID, active RFID, Bluetooth, and Wi-Fi. The communication circuit 62 can also include a unique identifier (ID) that can be used to distinguish each load sensor from other sensors. In one example, the unique ID can be the ID of an RFID tag. The antenna 64 is configured to convert the electrical signal corresponding to the measurement value from the communication circuit 62 into radio waves, thereby wirelessly transmitting the measurement value through the patient's skin to an external wireless reader 42 located outside the patient's body.

[0031] like Figure 2 As further shown in FIG, the smart fixture 40 may include a power device 66 configured to supply power to the strain gauge 60 and the communication circuit 62. In at least some examples, the power device 66 may include an energy harvesting device configured to capture energy from a suitable energy source separate from the smart fixture 40. For example, the energy source may be radio waves transmitted from the external wireless reader 42. Alternatively, the power device 66 may capture energy from the patient's body itself or from another external source, such as a source external to the patient's body. More generally, the energy source may include, but is not limited to, sensed kinetic energy, electric fields, magnetic fields, and the like. However, in a preferred embodiment, the power device 40 does not include a typical electrochemical battery.

[0032] In one configuration, each load sensor 52, 54 may have its own dedicated communication circuit 62, antenna 64, and / or power device 66, which is local to the respective load sensor (i.e., as an integrated package). In this configuration, the primary load sensor 52 may transmit a first wireless signal indicating the amount of strain monitored by the primary load sensor 52 (i.e., the primary strain value), while the reference load sensor 54 may simultaneously transmit a second wireless signal indicating the amount of strain monitored by the reference load sensor 54 (i.e., the reference strain value). In other embodiments, the smart fixture 40 may have a common communication circuit 62, antenna 64, and / or power device 66 that may be shared across the entire fixture 40 (i.e., where each load sensor 52, 54 is in electrical communication with the shared communication circuit 62, antenna 64, and / or power device 66). Additional embodiments and disclosure of the smart fixture 40 are provided in US 2019 / 0038214, which is incorporated by reference in its entirety for all purposes.

[0033] As described above, the external wireless reader 42 is configured to wirelessly receive data from the smart fixture 40 through the patient's skin. To facilitate these communications, Figure 3 As shown generally, the external wireless reader 42 typically includes one or more antennas 70, such as radio frequency identification (RFID) antennas, that communicate with a portable computing device 72. The antennas 70 can be configured to attach directly to the patient's body or to an external surface of clothing. Such attachment can be facilitated by the use of one or more straps 73, slings, brackets, adhesive patches, elastic sleeves, hoops, and the like. In one embodiment, the antenna 70 can be disposed within a flexible fabric carrier 74 that can be specifically adapted to conform to the contours of the user's body. The antenna 70 can generally comprise a loop having a length adapted to extend parallel to the bone plate 12 and a width adapted to extend transversely to and / or circumferentially around the bone plate 12. The length controls the amount of plate the antenna can communicate with, while the width affects the depth of tissue through which the antenna can receive a reliable signal. In one configuration, the length of the antenna 70 is greater than the distance between the primary load sensor 52 and the reference load sensor 54. In another configuration, the length of the antenna 70 is at least 10% greater than the distance between the primary load sensor 52 and the reference load sensor 54. In one embodiment, the antenna 70 can have a length between about 20 cm and about 50 cm, or between about 25 cm and about 40 cm. Similarly, the antenna 70 can have a width between about 12 cm and about 20 cm, or between about 14 cm and about 17 cm.

[0034] like Figure 4As shown, the portable computing device 72 may include short-range communication circuitry 76 and / or power transmission circuitry 78 in communication with the antenna 70. The short-range communication circuitry 76 is operable to receive digital information from the smart fixture 40 via the antenna 70. In some embodiments, the short-range communication circuitry 76 may include a digital receiver or transceiver, such as an RFID transceiver or a near-field communication (NFC) transceiver. In one configuration, the antenna 70 may be operable to simultaneously communicate with each load sensor 52, 54, for example, by using different data transmission frequencies or by using different digital identifiers provided with the strain data. The power transmission circuitry 78 may include an inductive charging circuit operable to supply electromagnetic power (i.e., an alternating magnetic field) via the antenna 70 to inductively power the smart fixture 40.

[0035] Continue to see Figure 4 , the portable computing device 72 may also include a processor 80, a wireless communication radio 82, and a user interface 84. The wireless communication radio 82 is operable to communicate with and over the wireless communication network 28 and may include a Bluetooth or Bluetooth low energy chipset, a Wi-Fi radio operable to communicate digitally using a communication protocol according to IEEE 802.11, or a cellular radio operable to communicate according to 4G, 5G, LTE, LPWAN, LTE-M, CAT-M1, NB-IoT protocols, etc. In some embodiments, the portable computing device 72 may also include a subscriber identity module (SIM) card to facilitate communication over a cellular network.

[0036] The processor 80 may be embodied as one or more digital computers, data processing devices, and / or digital signal processors (DSPs), which may have one or more microcontrollers or central processing units (CPUs), read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a high-speed clock, analog-to-digital (A / D) circuitry, digital-to-analog (D / A) circuitry, input / output (I / O) circuitry, and / or signal conditioning and buffering electronics. The processor 80 is configured to implement or perform one or more electronic functions by executing software or firmware code stored in non-volatile memory accessible by the processor 80. For example, the processor 80 may be capable of implementing code that reads one or more strain values from the smart fixture 40, selects an averaged or filtered representative strain value, communicates with a user via the user interface 84, and / or communicates via the wireless communication radio 82 over the wireless communication network 28.

[0037] The portable computing device 72 may communicate with the antenna 70 using a wired communication link or a wireless communication link. In one configuration, such as Figure 3As generally shown in FIG, the portable computing device 72 can be electrically coupled to the antenna 70 using a wired tether 86. Such a design can have the beneficial effect of providing a self-contained diagnostic device that relies only on a single power source. More specifically, in the absence of the wired tether 86, the antenna 70 would require a first power source to communicate with / power both the sensor and the portable computing device 72, while the portable computing device 72 would require a second power source. Coupling the two elements reduces the need for the consumer to maintain sufficient battery power on two separate devices while also reducing device complexity. The wired tether 86 also enables the portable computing device 72 to be kept in a convenient and accessible location during data acquisition without the need for straining to view a screen that may otherwise be out of the patient's field of view. In one configuration, the antenna portion of the device may also include a holster or other securing mechanism for attaching and securing the portable computing device 72 when not in use.

[0038] In another embodiment, the portable computing device 72 can communicate wirelessly with the antenna 70 using a suitable wireless protocol. For example, in one configuration, the portable computing device 72 can be a smartphone or tablet device that communicates wirelessly with the antenna (and / or communication circuitry disposed thereon) using, for example, a Bluetooth protocol.

[0039] like Figure 4 As further shown, the user interface 84 may include a visual display 88 (such as an LCD or OLED display), and one or more input devices 90 such as buttons or a touch screen digitizer. Figure 5 As generally shown in , the display 88 is operable to provide one or more visual cues to the patient, such as indicating the start of a reading (at 92), verifying sensor alignment (at 94), indicating posture for a reference measurement and the occurrence of a reference measurement (at 96), indicating posture for a load bearing measurement and the occurrence of a load bearing measurement (at 98) and / or uploading measurement data to a data server / cloud via the wireless communication network 28 (at 100).

[0040] Figure 6A method 110 for collecting and aggregating patient healing data using the present system 10 is schematically illustrated. The method 110 begins at 112, where the antenna 70 is positioned in contact with or outwardly proximate to the skin surface of the body. In some configurations, such as when using an RFID communication protocol, the antenna 70 can be positioned so that it is approximately centered above / radially outwardly of at least one implantable primary load sensor 52 and at least one implantable reference load sensor 54, each of which is in direct physical communication with the bone plate 12 or other bone fixation device. One or more straps 73 or sleeves can be used to hold the antenna 70 in place during testing, such as by wrapping around a portion of the wearer's body. Once the antenna 70 is in place and secured to the wearer's body at 112, the portable computing device 72 can receive an indication at 114 that the patient / user wishes to begin testing and begin collecting strain data. This indication 114 can be received via the input device 90 and can include, for example, a physical or virtual button press.

[0041] Once the indication to start has been received at 114, the processor 80 may power the antenna 70 via the power transmission circuit 78 (at 116), which in turn may power on and / or activate the sensors 52, 54. Thereafter, the processor 80 may check the presence and / or strength of the data signal returned from each sensor 52, 54 to determine if the device is operational and correctly positioned (at 118). If the signal-to-noise ratio is too low (e.g., Figure 5 If the sensor is working well and returning an adequate signal, the processor 80 may then instruct the user via the display 88 (at 120) on how to position their body. For example, Figure 5 As shown at 96, the display 88 may show a picture of a person sitting to indicate that the patient should be in a sitting position. This position may be automatically confirmed, for example, by the expiration of a countdown timer, the user actuating a button to confirm the position, or by orientation data collected from an accelerometer or inertial measurement unit disposed on the antenna 70.

[0042] Once the user's location has been verified (directly or indirectly), the processor 80 may receive measurement data from the load sensors 52, 54 via the antenna 70 and the communication circuit 76 (at 122). After receipt, the data may optionally be filtered or smoothed (at 124) by the portable computing device 72 to remove communication or measurement noise, erroneous harmonics, etc. Exemplary filtering techniques may employ low-pass or band-pass filtering techniques and / or data averaging techniques to remove noise within the signal. Additional techniques may include various limiting or sampling strategies that are operable to isolate a subset of the total received signal having the smallest mean or total variance (e.g., root mean square (RMS) variance).

[0043] Once any onboard data processing is complete (if any such processing is required), the processor 80 may package the strain data from the load sensors 52, 54 (in raw and / or filtered / clipped form) along with a unique identifier corresponding to at least one of the subject's identity or the identity of the implantable smart fixation device 40 or the strain sensor mounted thereon (at 126). Packaging such data may include generating a digital file in a memory that includes the sensor data in a separated form along with header or metadata information including the date / time of reading, device data, environmental data, and / or subject / device identification data. The packaged data / data file may then be transmitted (at 128) to the data server 20 via the wireless communication network 28, where it may then be aggregated and / or recorded (at 132) in conjunction with the unique patient identifier.

[0044] The system of the present invention can be operably configured to interpret the acquired strain data to determine the relative amount of support provided by the bone plate due to the fracture using the difference in readings between the primary load sensor 52 and the reference load sensor 54 (at 130). In practice, such analysis can be performed using the processor 80 or by the data server 20. If the analysis is performed by the device processor 80, the results of the analysis will be packaged along with the filtered data or raw data and a unique identifier before the information is transmitted.

[0045] In one configuration, the relative amount of support provided by the bone plate can be expressed as the ratio of the strain sensed by the primary load sensor 52 to the strain sensed by the reference load sensor. As the bone heals, this value can be expected to decrease toward 1.0 (to account for different biomechanical dynamics, in which strain may not be uniform along the length of the bone). A ratio greater than 1.0 would indicate that the bone plate is carrying a greater amount of load across the fracture than at points distal to the fracture.

[0046] In some embodiments, the processor 80 may also normalize the measurements or ratios obtained during the load-bearing posture (e.g., the load-bearing ratio) using the measurements or ratios obtained when unloaded (e.g., the unloaded ratio). For example, when monitoring a fracture in the femur, the load-bearing posture may involve the patient standing upright, whereas the unloaded posture may involve the patient being in a sitting position. To accomplish this, the method 110 may repeat the instruction / measurement steps (generally at 120-124) while instructing the patient via the display 88 to position themselves in different body positions (e.g., at Figure 6 120b in and Figure 5 98 in FIG. 1 ). In one configuration, the first suggested body position would be a reference position where there is substantially no load on the fracture. The second position would then be a position where a load is applied to the fracture.

[0047] In one configuration, the normalization mentioned above may simply involve calculating the ratio of the principal strain to the reference strain as the ratio of the strain change. In other words, the system may calculate the delta strain increment at the fracture from the unloaded pose to the loaded pose, and then divide this value by the similarly calculated delta strain increment at the reference position (i.e., from the unloaded pose to the loaded pose). This normalization may remove ratio anomalies that may be caused by different baseline readings between sensors. In one configuration, such as in Figure 5 When a load bearing posture is indicated, the processor 80 may compare the strain from the reference sensor 54 in the load bearing posture to the strain from the sensor in the unloaded posture, as generally shown at 98 in FIG.

[0048] To ensure that sufficient load is applied to the bone to achieve meaningful data points, the processor 80 can monitor the absolute strain and / or delta strain at the fracture to ensure that it is above a predetermined threshold when in the indicated load-bearing posture. If the strain is below the threshold, the processor 80 can instruct the wearer to apply a greater load to the fractured bone (such as Figure 5 If the ratio or difference is above a threshold, the reading can be recorded with confidence that the bone in the load-bearing posture is carrying a sufficient amount of load for the results to be meaningful.

[0049] In other embodiments, the portable computing device 72 may instead instruct the patient (at 120) to engage in some dynamic movement, rather than taking measurements during a static loading condition. For example, the portable computing device 72 may instruct the patient to walk, perform some stretches, or perform other functional activities, such as standing from a seated position, climbing stairs, etc. In this configuration, the processor 80 may examine the strain readings over time to identify peak loads throughout the functional activity, rather than simply filtering and / or averaging the received strain readings to obtain a single static strain value. These peak load values / ratios may then be normalized to the identified minimum load value / ratio, rather than requiring discrete load-bearing and load-free postures.

[0050] Once the support ratio is obtained, the value can be recorded similarly in conjunction with the subject's identifier. In one configuration, each patient can have multiple data points associated with their unique patient identifier. Each data point can represent a test result collected at a different time point. Figure 7 A plurality of patient data points 140 are schematically shown, each data point representing a load ratio 142 acquired over time 144. Figure 7 As shown, from these plurality of data points 140, a trend line 146 may be constructed representing the patient's healing progress over time.

[0051] Upon receiving a request from a user or medical professional 32 ( Figure 6 At 134), the data server 20 may Figure 8 The hosted user interface / physician interface 34 shown in FIG. 1 visually represents aggregated patient data. In one configuration, the physician interface 34 can be a web-based display that graphically illustrates the healing progress of one or more patients 148, for example, by displaying collected data points 140 and / or trend lines 146 over time 142. In one configuration, the physician interface 34 can include, for example, Figure 8 The summary screen shown enables the physician to quickly scan the progress and compliance of multiple patients, each of whom uses the system of the present invention and periodically transmits their respective patient data 24 to the data server 20. Selecting any patient switches the physician interface 34 from the summary screen to a more detailed graphical display of the selected patient's trends, such as Figure 7 shown.

[0052] In one configuration, Figure 7As shown in FIG, the data server 20 can calculate and display a patient-specific trajectory range 150 within which the patient's actual trend line 146 is expected to fall over time. In one configuration, the patient-specific trajectory range 150 can be a statistical assessment based on one or more qualitative and / or quantitative attributes / metrics extracted from the patient's medical records or otherwise input into the data server 20. These characteristics can include factors such as the nature and location of the fracture, the subject's height, weight, age, sex, metabolic profile, blood pressure, preexisting conditions, complex risk factors / comorbidities 152 ( Figure 8 ), or other such factors that may affect healing. In some embodiments, the trajectory range 150 may also be influenced by empirical data obtained from previous patients. For example, the data server 20 may maintain a machine learning model (e.g., a supervised or unsupervised learning model) in which empirical evidence obtained from previous patients is used to improve the predictive accuracy of the model for future patients. The patient-specific trajectory range 150 may include a predicted trajectory 154 along with one or more confidence intervals 156 that diverge over time. In one configuration, the patient-specific trajectory range 150 may be a static trajectory range 150 that is calculated from the day the bone is fixed (i.e., day 0) and is not updated. By not continually improving the model, the medical professional may understand whether the patient is healing as expected or whether there are unforeseen complications that need to be addressed.

[0053] In some embodiments, the data server 20 may further attempt to extrapolate the trajectory at each step (i.e., where the most recent data point is always day 0 and the previous trend line is an additional input into the model). This forward-looking trajectory 158 can provide advance notice to medical professionals if the direction of the curve may cause concern later. For example, Figure 7 The forward-looking trajectory 158 in is predicting a slowdown in healing progress over the next 1-2 weeks, which may be outside the expected boundaries. This prediction can alert the physician that something may be complicating the healing progress and may require further investigation. In addition, in one configuration, if one of the data points or the forward-looking healing trajectory is outside the confidence interval, the data server 20 can provide a warning via the physician interface 34. In this way, the more frequent monitoring provided by the system of the present invention, together with the enhanced data visualization and predictive analysis, can lead to a more complete understanding of how well the patient is healing relative to reasonable expectations. If complications begin to occur, this enhanced understanding can enable the physician to intervene at an earlier stage. Likewise, this data can also be used to provide guidance regarding recommended physical therapy treatments and recommended overall patient activity levels.

[0054] In one configuration, in addition to being displayed to the physician via the hosted interface 34, the recorded patient data points 140, the patient-specific trajectory range 150, the prospective trajectory 158, and / or one or more qualitative summaries can also be displayed to the patient via the display 88. In this case, the healing process can be gamified, for example, by celebrating or providing virtual rewards when certain milestones are reached. Similarly, the portable computing device can automatically or with remote guidance / input from the physician convey prompts or behavioral suggestions to help the patient maintain compliance with the prescribed course of treatment.

[0055] Figure 9 A schematic diagram illustrates one way to attach the external wireless reader 42 and / or antenna 70 to a user's body, and more specifically, to the upper thigh, as would be required for a femoral fracture. In such applications, attachment presents challenges because the thickness of the thigh muscles varies depending on the patient's posture. For example, when a patient transitions from sitting to standing, their thigh circumference decreases significantly. If not accounted for, this decrease in leg circumference could cause the external wireless reader 42 to slide downward from its intended position. To prevent this slippage, in one embodiment, the external wireless reader 42 may include one or more elastic bands 160 configured to be secured around the circumference of the patient's body. These elastic bands 160 are preferably tension-fitted, elastically stretching around the patient's limb while applying a compressive force to the patient's skin. In some embodiments, the external wireless reader 42 may also include one or more braces 162 configured to be secured around the joint of a fractured bone. For example, in a femoral fracture, the external wireless reader 42 may include a knee brace 164 configured to extend around the patient's knee joint. The antenna 70 can then be rigidly positioned relative to the brace 162. This design can be advantageous because the circumference of the joint does not change significantly based on posture, and similarly, the position of the fracture relative to the joint remains constant. This design will not rely solely on a contracting elastic band to maintain positioning, which may prove uncomfortable for some patients. In an alternative embodiment, a hip brace or band can be used instead of the knee brace 162.

[0056] The present technology represents an advancement in the physician's ability to more proactively monitor the progress of healing of internally fixed fractures. Using this increased quantitative monitoring, which is particularly well-suited for remote monitoring / telemedicine, the physician can have a more complete picture of how the bone is ossifying than is available with current practice. With this information, the physician can more proactively tailor physical therapy regimens, advise the patient on acceptable activity levels or diets, or even take proactive intervention steps if necessary. Because the rate of bone healing is generally slow, the present device may not need to be worn continuously. Instead, the external wireless reader 42 may be more like a blood pressure cuff, in that it only needs to be worn during the test (which may only need to be worn a few times per week).

[0057] Other aspects and advantages of the present technology are provided in the following clauses:

[0058] Item 1. A patient monitoring system for monitoring ossification of an internally fixed fracture in a bone of a subject, the system comprising: an implantable fixation device operable to attach to the bone, the fixation device comprising: a bone plate configured to be fixed to the bone on opposite sides of the fracture; a primary load sensor disposed at a first position on the bone plate, the first position operable to be positioned directly adjacent to the fracture, the primary load sensor comprising: a first strain sensor operable to monitor the amount of strain (principal strain) at the first position in the bone plate; and a communication circuit operable to transmit a first wireless signal indicative of the amount of principal strain; a reference load sensor disposed on the bone plate and At a second position spaced apart from the first position, the reference load sensor includes: a second strain sensor, the second strain sensor being operable to monitor the strain amount (reference strain) at the second position in the bone plate; and a communication circuit being operable to transmit a second wireless signal indicating the reference strain amount; an external wireless reader, the external wireless reader including an antenna, a processor and a wireless communication radio device, wherein the processor is configured to: receive the first wireless signal and the second wireless signal via the antenna; and use the wireless communication radio device to transmit a signal to a data server via a wireless communication network, the signal indicating the main strain amount, the reference strain amount, and the system also including a unique identifier corresponding to at least one of the subject or the implantable fixation device.

[0059] Clause 2. The patient monitoring system of clause 1, further comprising the data server in digital communication with the external wireless reader; wherein at least one of the processor or the data server is configured to: determine a relative amount of support provided by the bone plate due to the fracture using the received indication of the principal strain and the received indication of the reference strain; and store the determined relative amount of support in a non-transitory memory in communication with at least one of the processor or the data server.

[0060] Clause 3. The patient monitoring system of Clause 2, wherein the processor or data server is configured to determine the relative amount of support provided by the bone plate by calculating a ratio of the principal strain to the reference strain.

[0061] Item 4. A patient monitoring system according to Item 3, wherein the processor is further configured to: prompt the subject to position the bone in a first unloaded posture and separately position the bone in a second load-bearing posture; determine the principal strain amount in each of the first unloaded posture and the second load-bearing posture; determine the reference strain amount in each of the first unloaded posture and the second load-bearing posture; and wherein at least one of the processor or data server is configured to determine the relative amount of support provided by the bone plate by calculating the ratio of the principal strain difference between the unloaded posture and the load-bearing posture to the reference strain difference between the unloaded posture and the load-bearing posture.

[0062] Clause 5. A patient monitoring system according to clause 4, wherein the external wireless reader further comprises a display, and wherein the processor is configured to prompt the subject via the display to position the bone in the first unloaded posture and separately in the second load-bearing posture.

[0063] Clause 6. A patient monitoring system according to clause 5, wherein the processor is configured to prompt the subject via the display to apply additional load to the bone if the principal strain in the load-bearing posture is less than a predetermined minimum threshold strain amount.

[0064] Clause 7. A patient monitoring system according to any of clauses 4-6, wherein at least one of the processor or data server is configured to determine the relative amount of support provided by the bone plate only when the principal strain in the load-bearing posture exceeds a predetermined minimum threshold strain amount.

[0065] Clause 8. A patient monitoring system according to any of clauses 1-7, wherein the external wireless reader further comprises an inductive charging circuit operable to power each of the primary load sensor and the reference load sensor via a magnetic field emitted from the antenna.

[0066] Clause 9. A patient monitoring system according to clause 8, wherein the external wireless reader comprises a wearable component in wired communication with a display device via a tether; and wherein the wearable component comprises an antenna disposed in a carrier having at least one band configured to extend around a portion of the subject.

[0067] Clause 10. The patient monitoring system of clause 9, wherein the wearable component further comprises the processor.

[0068] Clause 11. The patient monitoring system of any of Clauses 9-10, wherein the fabric carrier is further secured to a brace operable to extend around a joint of the subject.

[0069] Clause 12. The patient monitoring system of any of clauses 1-11, wherein the antenna has a length, and wherein the length of the antenna is greater than a spacing between the first position and the second position.

[0070] Clause 13. A method for monitoring bone fracture ossification from a plurality of subjects, the method comprising: receiving a plurality of data sets from the plurality of subjects via a wireless communication network, each data set representing a plurality of strain measurements obtained from a smart fixation device fixed to a bone of the subject across a bone fracture, the plurality of strain measurements comprising at least a first strain measurement indicating an amount of load carried by the fixation device across the bone fracture (principal strain) and at least a second strain measurement indicating an amount of load carried by the fixation device at dense bone (reference strain); calculating a ratio of the principal strain to the reference strain for each of the plurality of data sets, storing each data set and each calculated ratio in a non-volatile memory in conjunction with a date and time of the strain measurement and a patient identifier indicating the source of the measurement; and providing a physician interface to graphically illustrate changes in the ratio over time for each of a plurality of different subjects.

[0071] Clause 14. The method according to clause 13 further includes maintaining a machine learning prediction model, which generates a predicted patient-specific healing trajectory for each subject, the patient-specific healing trajectory including a predicted trajectory and a confidence interval, the confidence interval representing the possible healing progression process starting at the time of bone fixation, the method also includes superimposing multiple data sets of the subject on a graphical representation of the predicted patient-specific healing trajectory within the physician interface; and wherein at least a subset of the received data sets and multiple secondary factors are used to improve the machine learning prediction model, the multiple secondary factors including at least two of the following: the nature and location of the fracture, the subject's height, weight, age, sex, metabolic characteristics, blood pressure, previous illness, complex risk factors or comorbidities.

[0072] Clause 15. The method of clause 14, further comprising: calculating a prospective healing trajectory for each subject, the trajectory extending forward in time from the subject's most recently acquired data set; and superimposing the prospective healing trajectory on the graphical representation of the predicted patient-specific healing trajectory.

[0073] Clause 16. The method of Clause 15, further comprising providing a warning via the physician interface if one of the data set or the prospective healing trajectory is outside the confidence interval.

[0074] Item 17. A method for collecting ossification data from an implantable intelligent fixation device disposed in a subject's body, the method comprising: energizing an external antenna to generate an alternating magnetic field and energizing a plurality of load sensors inductively, the load sensors being configured to contact a bone plate, the bone plate being fixed to the bone across a fracture; receiving a wireless data signal from each of the plurality of load sensors via the external antenna, the wireless data signal indicating an amount of strain experienced by the bone plate; identifying a representative strain value from each wireless data signal; and determining the relative amount of load borne by the bone plate across the fracture by dividing a first strain value indicating an amount of strain experienced by the bone plate at the fracture by a second strain value indicating an amount of strain experienced by the bone plate away from the fracture.

[0075] Clause 18. The method according to Clause 17 further includes: prompting the subject via an electronic display to position the bone or the subject's body in a first unloaded position; and prompting the subject via the electronic display to position the bone or the subject's body in a second load-bearing position, wherein the bone plate undergoes at least a predetermined minimum amount of strain in the load-bearing position; and wherein each of the first strain value and the second strain value includes a difference between the strain amounts measured in the load-bearing position and the unloaded position.

[0076] Clause 19. The method of Clause 18, further comprising providing a warning to the subject if the amount of strain in the load-bearing posture is less than the predetermined minimum amount of strain.

[0077] Benefits, other advantages, and solutions to problems have been described with respect to specific embodiments. However, benefits, advantages, solutions to problems, and any elements that cause or make apparent any benefit, advantage, or solution are not to be construed as critical, required, or essential features or elements of any or all the claims unless such benefits, advantages, solutions, or elements are expressly recited in such claims.

[0078] Furthermore, the embodiments and limitations disclosed herein are not dedicated to the public under the doctrine of dedication if the embodiments and / or limitations: (1) are not expressly claimed in the claims; and (2) are, under the doctrine of equivalents, equivalents to the express elements and / or limitations in the claims.

[0079] Additional embodiments of external wireless readers are provided in the appendix filed herewith.

Claims

1. A patient monitoring system for monitoring ossification of an internally fixed fracture in a bone of a subject, the system comprising: An implantable fixation device operable to attach to the bone, the fixation device comprising: a bone plate configured to be secured to the bone on opposite sides of the fracture; a primary load sensor disposed at a first location on the bone plate, the first location being operable to be positioned directly adjacent the fracture, the primary load sensor comprising: a first strain sensor operable to monitor a principal strain, the principal strain being the amount of strain at the first location in the bone plate; and a communication circuit operable to transmit a first wireless signal indicative of the amount of principal strain; a reference load sensor disposed at a second location on the bone plate spaced apart from the first location, the reference load sensor comprising: a second strain sensor operable to monitor a reference strain, the reference strain being an amount of strain at the second location in the bone plate; and a communication circuit operable to transmit a second wireless signal indicative of the amount of reference strain; An external wireless reader comprising an antenna, a processor, and a wireless communication radio, wherein the processor is configured to: receiving the first wireless signal and the second wireless signal via the antenna; transmitting a signal to a data server over a wireless communication network using the wireless communication radio, the signal indicating the primary strain amount, the reference strain amount, and also including a unique identifier corresponding to at least one of the subject or the implantable fixation device; The processor is further configured to: prompting the subject to position the bone in a first, unloaded position, and individually positioning the bone in a second, load-bearing position; determining a principal strain amount in each of the first unloaded posture and the second load-bearing posture; determining a reference strain amount in each of the first unloaded posture and the second load-bearing posture; and wherein at least one of the processor or the data server is configured to determine a relative amount of support provided by the bone plate by calculating a ratio of a principal strain difference between the first unloaded posture and the second load-bearing posture to a reference strain difference between the first unloaded posture and the second load-bearing posture.

2. The patient monitoring system of claim 1 , further comprising said data server in digital communication with said external wireless reader; wherein at least one of the processor or the data server is configured to: using the received indication of the principal strain and the received indication of the reference strain to determine a relative amount of support provided by the bone plate due to the fracture; and The determined relative amount of support is stored in a non-transitory memory in communication with at least one of the processor or the data server.

3. The patient monitoring system of claim 2, wherein the processor or data server is configured to determine the relative amount of support provided by the bone plate by calculating a ratio of the principal strain to the reference strain.

4. The patient monitoring system of claim 3 , wherein the external wireless reader further comprises a display, and wherein the processor is configured to prompt the subject via the display to position the bone in the first unloaded posture and separately in the second load-bearing posture.

5. The patient monitoring system of claim 4, wherein the processor is configured to prompt the subject via the display to apply additional load to the bone if the principal strain in the load-bearing posture is less than a predetermined minimum threshold strain amount.

6. The patient monitoring system of claim 1 , wherein at least one of the processor or the data server is configured to determine the relative amount of support provided by the bone plate only when the principal strain in the load-bearing posture exceeds a predetermined minimum threshold strain amount.

7. The patient monitoring system of claim 1 , wherein the external wireless reader further comprises an inductive charging circuit operable to power each of the primary and reference load sensors via a magnetic field emitted from the antenna.

8. The patient monitoring system of claim 7, wherein the external wireless reader comprises a wearable component in wired communication with a display device via a tether; and The wearable component includes an antenna disposed in a carrier having at least one band configured to extend around a portion of the subject.

9. The patient monitoring system of claim 8, wherein the wearable component further comprises the processor.

10. The patient monitoring system of claim 8, wherein the carrier is further secured to a brace operable to extend around a joint of the subject.

11. The patient monitoring system of claim 1 , wherein the antenna has a length, and wherein the length of the antenna is greater than a spacing between the first location and the second location.

12. A method of monitoring fracture ossification from a plurality of subjects, the method comprising: prompting the subject to position a bone in a first, unloaded position, and individually positioning the bone in a second, load-bearing position; receiving, via a wireless communication network, a plurality of data sets from a plurality of subjects, each data set representing a plurality of strain measurements acquired from a smart fixation device fixed to a bone of the subject across a bone fracture, the plurality of strain measurements comprising at least a first strain measurement indicating a principal strain in each of a first unloaded posture and a second load-bearing posture, the principal strain being the amount of load carried by the fixation device across the bone fracture, and at least a second strain measurement indicating a reference strain in each of the first unloaded posture and the second load-bearing posture, the reference strain being the amount of load carried by the fixation device at dense bone; calculating a ratio of a principal strain difference between the first unloaded posture and the second load-bearing posture to a reference strain difference between the first unloaded posture and the second load-bearing posture for each of the plurality of data sets; storing each data set and each calculated ratio in a non-volatile memory in association with the date and time of the strain measurement and with a patient identifier indicating the source of the measurement; as well as A physician interface is provided to graphically show changes in the ratio from each of a plurality of different subjects over time.

13. The method of claim 12, further comprising maintaining a machine learning prediction model that generates a predicted patient-specific healing trajectory for each subject, the patient-specific healing trajectory comprising a predicted trajectory and a confidence interval that represents a likely course of healing progression initiated at the time of bone fixation, the method further comprising overlaying, within the physician interface, a plurality of datasets for the subject on a graphical representation of the predicted patient-specific healing trajectory; and The machine learning prediction model is improved using at least a subset of the received dataset and multiple secondary factors, wherein the multiple secondary factors include at least two of the following: the nature and location of the fracture, the subject's height, weight, age, sex, metabolic characteristics, blood pressure, previous illnesses, complex risk factors or comorbidities.

14. The method according to claim 13, further comprising: calculating a prospective healing trajectory for each subject, the trajectory extending forward in time from the subject's most recently acquired dataset; as well as The prospective healing trajectory is superimposed on the graphical representation of the predicted patient-specific healing trajectory.

15. The method according to claim 14, further comprising: If one of the data set or the prospective healing trajectory is outside the confidence interval, a warning is provided via the physician interface.

16. A method for collecting ossification data from an implantable intelligent fixation device disposed in a subject, the method comprising: energizing an external antenna to generate an alternating magnetic field and inductively energizing a plurality of load sensors disposed in contact with a bone plate secured to the bone across the fracture; receiving a wireless data signal from each of the plurality of load sensors via the external antenna, the wireless data signal indicating an amount of strain experienced by the bone plate; identifying a representative strain value from each wireless data signal; prompting the subject to position the bone in a first, unloaded position, and individually positioning the bone in a second, load-bearing position; determining a principal strain in each of the first unloaded posture and the second load-bearing posture, the principal strain being the amount of strain experienced by the bone plate at the fracture; determining a reference strain in each of the first unloaded posture and the second load-bearing posture, the reference strain being the amount of strain experienced by the bone plate away from the fracture; and The relative amount of support provided by the bone plate is determined by calculating a ratio of a principal strain difference between the first unloaded posture and the second load-bearing posture to a reference strain difference between the first unloaded posture and the second load-bearing posture.

17. The method of claim 16, further comprising providing a warning to the subject if the amount of strain in the load-bearing posture is less than a predetermined minimum amount of strain.

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