Method and computer program for creating manufacturing data for the production of an orthopedic device

Abstract

The invention relates to a method for creating manufacturing data for the production of an orthopedic device, which is dedicated to support or replace a body part of a patient, comprising the steps: - providing a predefined functional stiffness of the orthopedic device to be produced to said processing unit, - providing a digital orthopedic model of the orthopedic device to be produced to said data processing unit, which fits the body part of the patient to be supported or replaced, - optimizing the provided digital orthopedic model by modifying at least one parameter, which relates to a functional stiffness property of the orthopedic device to be produced, based on said provided predefined functional stiffness through said data processing unit, so that the orthopedic device to be produced reaches the predefined functional stiffness within a range of tolerance, and - creating the manufacturing data based on the optimized digital orthopedic model through said data processing unit.

Description

[0001] Method and computer program for creating manufacturing data for the production of an orthopedic device

[0002] The invention relates to a method for creating manufacturing data for the production of an orthopedic device, which is dedicated to support or replace a body part of a patient.

[0003] The invention relates also to a computer program thereto.

[0004] Orthopedic products, such as orthosis or prosthesis or even exoskeletons, must be developed and adapted precisely and exactly to the conditions of the handicapped person or the person to be supported in order to provide the best possible care for the body parts of the handicapped person. Even today, a large number of manual and hand-operated steps are necessary to manufacture such an orthopedic device.

[0005] In this context, prosthesis replace limbs that do not exist or no longer exist in terms of form and / or functionality. Prosthesis are used in particular on the upper and lower extremities and include, for example, prosthetic hands or prosthetic feet that are fixed to an amputation stump via one or more joints. In the case of a lower leg that is only partially present, a prosthetic foot is attached, if necessary, with a prosthetic ankle joint and a lower leg tube is fixed to the amputation stump via a lower leg socket. Prosthetic legs with a prosthetic knee joint are attached to a femoral stump via a femoral socket. In the case of upper limb prostheses, the prosthetic component is fastened correspondingly via a forearm socket or an upper arm socket. Sometimes, a blade is used as a prosthetic foot. The blade is attached often directly to the socket to build a foot spring. Here, the stiffness has a great influence on the comfort of the movement and must be taken into account for appropriate applications. To optimize the stiffness of the blade (for adjusting the spring reaction of the prostheses) is an important issue.

[0006] The prosthesis socket to which the other distal prosthesis components are attached are predominantly cup-shaped and have a proximal entry opening into which the amputation stump is inserted. Fixation of the prosthesis socket, which usually has a circumferential socket wall, can be based on different principles. A liner (prosthetic liner) is then often placed between the prosthetic socket and the limb, whereby the liner has an elastomeric material to cushion the limb against the hard wall of the prosthetic socket. In addition, adhesive and sealing properties of the material of the prosthetic liner are exploited to adhere to the skin surface and / or to be able to realize suction socket technology.

[0007] The prosthesis liner, which can be sleeve-shaped and optionally with a closed distal cap, represents the intermediate piece or interface between the limb and the prosthesis socket. Such liners are known in numerous embodiments. They are usually made of an elastic plastic material, such as polyurethane or silicone, and are formed with a wall thickness such that a cushioning effect occurs. Due to their elasticity, the liners are intended to fit closely to the body part to be fitted (e.g. amputation stump) and in this way form a cushioning intermediate layer between the liner and a prosthetic socket to which a prosthesis for an amputated limb can be attached. The system of prosthetic socket and liner thus serves to attach a prosthesis to the limb to be fitted. In a known technique, this attachment can be assisted by creating a negative pressure between the liner and the amputation stump and / or between the liner and the prosthesis socket, by which the respective friction pairing is reinforced.

[0008] In contrast, an orthosis is not intended to replace limbs, but to support the patient's joint, skeleton and / or musculature. For this purpose, the orthosis is attached externally to the body part to be fitted. If joints are supported with the aid of an orthosis, the orthosis must often also have a joint or a certain range of motion so that patient’s joints to be supported remain mobile.

[0009] In practice, to produce an orthotic device, the orthopedic technician must create a negative plaster of the body part to be supported. Then, a positive mold is produced based on the negative plaster, whereby the positive mold is corrected from the orthopedic technician. Using the positive mold, the orthotic device is produced, e.g. using a vacuum thermoforming. Now, this orthotic device is ready for the first fitting with patient. After the first fitting of the orthotic device with the patient, the orthopedic technician usually has to further manipulate the orthotic device in order to best adapt it to the patient's needs. However, this is a very time-consuming process and not comfortable for the patient.

[0010] During the manufacturing of an ankle foot orthotic (AFO), adjusting the trim line is also a common adjustment in the traditional process where the technician creates the AFO typically with too much material at the joint area and then iteratively adjusts the stiffness by removing material. This approach has two major downsides. First, it is not empirical but rather based on feedback from the patient, second, the technician is hesitant to remove too much material, a step which cannot be undone. AFOs generated in the traditional process are thus typically stiffer then actually desired.

[0011] In US 2018 / 0046775 A1 , a method for producing an orthosis based on patient data of the at least one body part and a digital orthosis model is disclosed. The digital orthosis model is generated based on the patient data of the at least one body part so that the digital orthosis model fits the patient data.

[0012] In WO 2019 / 129419 A1 , a method for producing an orthopedic device is disclosed. Based on patient data, a patient model is created. Then, a virtual representation of the orthopedic device is generated based on the patient model, whereby the orthopedic device is physically created based on said virtual representation. In US 8,838,263 B2, a method for producing an orthotic device is disclosed, whereby an orthotic model is generated based on patient scan data and technician expertise. Then, the orthotic device is fabricated using the orthotic model.

[0013] It is an object of the present invention to provide a better method and computer program for creating manufacturing data for the production of an orthopedic device, so that the orthopedic device is best adapted to the patient's needs and boundary conditions.

[0014] This object of the present invention is implemented by means of the method according to claim 1 . Advantageous embodiments are then found in the depended claims.

[0015] According to claim 1 , a method for creating manufacturing data for the production of an orthopedic device, which is dedicated to support or replace a body part of a patient, comprising the steps:

[0016] - providing a predefined functional stiffness of the orthopedic device to be produced to said processing unit,

[0017] - providing a digital orthopedic model of the orthopedic device to be produced to said data processing unit, which fits the body part of the patient to be supported or replaced,

[0018] - optimizing the provided digital orthopedic model by modifying at least one parameter, which relates to a functional stiffness property of the orthopedic device to be produced, based on said provided predefined functional stiffness through said data processing unit, so that the orthopedic device to be produced reaches the predefined functional stiffness within a range of tolerance, and

[0019] - creating the manufacturing data based on the optimized digital orthopedic model through said data processing unit. The provided predefined functional stiffness of the orthopedic device to be produced relates to a functional stiffness parameter, which is a target value of functional stiffness of the orthopedic device to support the patient accordingly. This functional stiffness can be a stiffness of an ankle foot orthotic around the ankle joint. The functional stiffness relates in general to the stiffness of the orthopedic device, which has an influence on the function of the orthopedic device for which the orthopedic device is to be used. The functional stiffness quantifying the resistance against bending, e.g. around a joint of the patient (for example around the ankle joint axis). The functional stiffness can be expressed in Nm (torque around the joint) or in Nm divided by degrees of rotation of the joint.

[0020] Further, a digital orthopedic model of the orthopedic device to be produced is provided to the data processing unit. The digital orthopedic model fits the body part of the patient to be supported or replaced. Hence, for providing the digital orthopedic model, the digital orthopedic model should be generated based on patient data, in particular based on a patient body model. Functional stiffness refers primarily to that stiffness of the orthopedic device to be produced that is intended to support the patient's medical anamnesis (for which the orthopedic device is used) and patient’s pathology.

[0021] The necessary data, the predefined functional stiffness of the orthopedic device to be produced and the digital orthopedic model of the orthopedic device to be produced, then are used to optimize the provided digital orthopedic model in such a way that at least one parameter is modified. The said at least one parameter to be modified relates to a functional stiffness property of the orthopedic device to be produced, e.g. the geometry of the orthopedic device to be produced, the material or a material property of the orthopedic device to be produced, the material thickness of relevant regions of the orthopedic device to be produced or other functional parameters of the orthopedic device to be produced, which have an effect on the stiffness of the device. All this parameters have an influence on the functional stiffness. Further, the provided digital orthopedic model is modified based on the predefined functional stiffness, so that the orthopedic device to be produced reaches the predefined functional stiffness within a range of tolerance. This could be reached by an optimization process which has the predefined functional stiffness as one boundary condition of the optimization process. This optimization process can be iterative, in which the functional stiffness is checked after each modification of at least one parameter of the digital orthopedic model, iterating until the predefined functional stiffness is best approximated.

[0022] If the optimization process is done, the manufacturing data based on the optimized digital orthopedic model is created. The creation of the manufacturing data, furthermore, could be based on a selected manufacturing process. An appropriate manufacturing process can be a 3D printing process, a lamination process or vacuum thermoforming.

[0023] The optimization process and the manufacturing data creating process are executed on the data processing unit automatically.

[0024] The inventive method results in a better compliance between patient’s pathology (i.e. gait parameters) and functionality of the orthopedic device. Further, the first fitting step to adapt the orthopedic device can be eliminated, because the modified model matches the predefined functional stiffness, so that the manufactured device also matches the predefined functional stiffness.

[0025] According to an embodiment, the orthopedic device is an orthosis, a prosthesis or an exoskeleton. In general, the term exoskeleton is used to describe a device that augments the performance of an able-bodied wearer, whereas the term orthosis describes a device that is used to assist a person with a limb pathology. The term prosthesis describes a device that replace or substitute a missing part of the body of the patient. According to an embodiment, the predefined functional stiffness of the orthopedic device concerns to a functional stiffness around a joint axis of the body part of the patient. This joint axis could be an ankle joint axis of an ankle of a foot orthotic device.

[0026] According to an embodiment, the orthopedic device is a foot orthotic device, a wrist brace or a scoliotic brace.

[0027] According to an embodiment, a geometry of the digital orthopedic model as a parameter is modified based on the predefined functional stiffness to alter the functional stiffness of the orthopedic device.

[0028] The geometry is defined, for example, by a trimline of the digital orthopedic model, whereby the trimline defines the outer boundary of the orthopedic device to be produced. In the optimizing process, the trimline can be modified based on the predefined stiffness to alter the functional stiffness of the orthopedic device to be produces. Therefore, the trim line of the orthotic device is a functional parameter to be optimized.

[0029] If the trim line is modified, the functional stiffness of the orthopedic device to be produced is changed. Therefore, the functional stiffness can be adjust exactly to the requirement of the patient.

[0030] According to an embodiment, the geometry is altered between a predefined minimum geometry and a predefined maximum geometry of the digital orthopedic model.

[0031] For example, if the geometry is defined by a trimline as an outer boundary of the orthopedic device to be produced, the trimline is altered between a predefined minimum trimline and a predefined maximum trimline. According to an embodiment, the material thickness in at least one section of the digital orthopedic model as a parameter is modified based on the predefined functional stiffness to alter the functional stiffness of the orthopedic device.

[0032] If the material thickness is changed in such a way that the material in said section is made thinner than before, the functional stiffness is going lower.

[0033] According to an embodiment, the material and / or material characteristic in at least on section of the digital orthopedic model as a parameter is modified based on the predefined functional stiffness to alter the functional stiffness of the orthopedic device.

[0034] According to an embodiment, the digital orthopedic model of the orthopedic device is provided by creating the digital orthopedic model based on a provided digital body model of the body part of the patient’s body through said data processing unit.

[0035] According to an embodiment, after modifying the at least one parameter, the modified orthopedic model is evaluated by a stiffness calculation. The stiffness calculation results a stiffness value or a stiffness value progression of the functional stiffness, if the modified orthopedic model would be used in real.

[0036] Preferably, a digital model of the patient's body part is used here to evaluate the modified model of the digital orthopedic model for functional stiffness. Patient data (patient's medical anamnesis and / or patient’s pathology) can also be included in the calculation to evaluate the digital orthopedic model. The stiffness calculation can be performed by a stiffness simulation (e.g. FE simulation) or an evaluation of a predictive algorithm (e.g. machine learning), which is based on historical manufacturing data and related functional stiffness. According to an embodiment, based on the result of the stiffness calculation, the step of modifying the at least one parameter is repeated further based on the result of the stiffness calculation until the result of the stiffness calculation achieved predefined functional stiffness within the range of tolerance.

[0037] Thus is an iterative process to approximate the predefined functional stiffness.

[0038] According to an embodiment, the stiffness calculation comprises boundary conditions interactions that mimic real-life boundary conditions of the patient.

[0039] It is a further aspect of the present invention to provide a method, whereby an orthopedic device is manufactured based on said created manufacturing data.

[0040] It is a further aspect of the present invention to provide a computer program having program code means adapted to perform the aforementioned method for creating manufacturing data, when the computer program is executed on a data processing unit.

[0041] The invention is described in more detail based on the enclosed drawings:

[0042] Figure 1 showing an ankle foot orthotic;

[0043] Figure 2 showing the overall process of the inventive method;

[0044] Figure 3 showing the optimization process in detail.

[0045] Figure 1 shows an ankle foot orthotic 10, which could be manufactured by using the present invention. For this, manufacturing data are created automatically at first. Then, the created manufacturing data are used to manufacture the ankle foot orthotic 10 by an automatic manufacturing process, e.g. 3D printing.

[0046] Figure 2 shows to overall process of the invention. A digital data processing unit 20 is provided with a predefined functional stiffness 21 from a database or a user input unit and with a digital orthopedic model 22 of the orthopedic device to be produced. Based on these input data 21 , 22, the digital data processing unit 20 creates manufacturing data 23 for the production of an orthopedic device 10.

[0047] Figure 3 shows in detail the optimization process to optimize the digital orthopedic model using the example of an ankle foot orthotic. At first, some target values 30 are provided for the process. These target values 30 includes at least a predefined functional stiffness of the ankle foot orthotic as an orthopedic device to be produced as well as a minimum trimline 31 and a maximum trimline 32. The minimum trim line 31 defines the outer boundary of the ankle foot orthotic to be produced, which has the lowest possible stiffness. The maximum trimline 32 defines the outer boundary of the ankle foot orthotic to be produced, which has the highest possible stiffness. In the example of figure 3, the predefined stiffness relates to a stiffness around the ankle joint axis. The minimum trimline 31 and the maximum trimline 32 are provided on a digital body model 33, which shows the relevant part of the foot of the patient to be supported. This digital body model 33 are also included in the target values 30.

[0048] Further, the target values 30 are inputted into the optimization process 50, which is an iterative search routine to find the optimal orthopedic model. Based on the body model 33 as well as the minimum 31 and maximum trim line 32, a digital orthotic model 41 as a digital orthopedic model is automatically designed in a design step 51 of the process 50. Some further variables (boundary conditions) can be considered by designing the model 41 , e.g. thickness, material(s), at least one material property, orientation and / or type of fibers (if a fiber reinforced composite material is used), laminate stack, etc.

[0049] The designed digital orthotic model 41 is now simulated in a simulation step 52 to obtain the functional stiffness of the orthotic model 41 in the considered axis, here in the ankle joint axis 42.

[0050] The result 53 of the simulation in the simulation step 52 is compared with the predefined functional stiffness provided as a target value before. The result 53 of the simulation shows an angle-force curve in both directions.

[0051] Based on this comparison, the preset values of the target values 30 are adapted and an optimized digital orthotic model 41 is designed to approximate the predefined functional stiffness. This optimized digital orthotic model 41 is also simulated in the simulation step 52 and the iterative process starts again until, the model 41 reaches the predefined functional stiffness within a range of tolerance.

[0052] Then, the optimized digital orthotic model 43, which reaches the predefined functional stiffness within a range of tolerance, is outputted from the optimization process 50. Based on the optimized digital orthotic model 43 outputted from the process 50, the manufacturing data could be created, so that the ankle foot orthotic can be produced directly or indirectly or can be produced automatically or manually.

[0053] Reference sign list

[0054] 10 orthopedic device I foot ankle orthotic

[0055] 20 data processing unit

[0056] 21 predefined functional stiffness

[0057] 22 digital orthopedic model

[0058] 23 manufacturing data

[0059] 30 target values

[0060] 31 minimum trimline

[0061] 32 maximum trimline

[0062] 33 digital body model

[0063] 41 digital foot ankle orthotic model

[0064] 42 ankle joint axis

[0065] 43 optimized digital foot ankle orthotic model

[0066] 50 iterative optimizing process

[0067] 51 design step

[0068] 52 simulation step

[0069] 53 result / comparison step

Claims

Claims1 . Method for creating manufacturing data (23) for the production of an orthopedic device (10), which is dedicated to support or replace a body part of a patient, comprising the steps:- providing a predefined functional stiffness (21 ) of the orthopedic device(10) to be produced to said processing unit,- providing a digital orthopedic model (22) of the orthopedic device (10) to be produced to said data processing unit (20), which fits the body part of the patient to be supported or replaced,- optimizing the provided digital orthopedic model (22) by modifying at least one parameter, which relates to a functional stiffness property of the orthopedic device (10) to be produced, based on said provided predefined functional stiffness (21 ) through said data processing unit (20), so that the orthopedic device (10) to be produced reaches the predefined functional stiffness (21 ) within a range of tolerance, and- creating the manufacturing data (23) based on the optimized digital orthopedic model (22) through said data processing unit (20).

2. Method as claimed in claim 1 , whereby the orthopedic device (10) is an orthosis, a prosthesis or an exoskeleton.

3. Method as claimed in claim 1 or 2, whereby the predefined functional stiffness (21 ) of the orthopedic device (10) concerns to a functional stiffness around a joint axis of the body part of the patient.

4. Method as claimed in one of the preceding claims, whereby the orthopedic device (10) is a foot orthotic device, a wrist brace or a scoliotic brace.

5. Method as claimed in one of the preceding claims, whereby a geometry of the digital orthopedic model (22) as a parameter is modified based on the predefined functional stiffness (21 ) to alter the functional stiffness of the orthopedic device (10).

6. Method as claimed in claim 4, whereby the geometry is altered between a predefined minimum geometry and a predefined maximum geometry of the digital orthopedic model (22).

7. Method as claimed on one of the preceding claims, whereby the material thickness in at least one section of the digital orthopedic model (22) as a parameter is modified based on the predefined functional stiffness (21 ) to alter the functional stiffness of the orthopedic device (10).

8. Method as claimed in one of the preceding claims, whereby the material and / or material characteristic in at least on section of the digital orthopedic model (22) as a parameter is modified based on the predefined functional stiffness (21 ) to alter the functional stiffness of the orthopedic device (10).

9. Method as claimed in one of the preceding claims, whereby the digital orthopedic model (22) of the orthopedic device (10) is provided by creating the digital orthopedic model (22) based on a provided digital body model (33) of the body part of the patient’s body through said data processing unit (20).

10. Method as claimed in one of the preceding claims, whereby after modifying the at least one parameter, the modified orthopedic model is evaluated by a stiffness calculation.11 . Method as claimed in claim 10, whereby based on the result of the stiffness calculation, the step of modifying the at least one parameter is repeated further based on the result of the stiffness calculation until the result of the stiffness calculation achieved predefined functional stiffness (21 ) within the range of tolerance.Method as claimed in claim 10 or 11 , whereby the stiffness calculation comprises boundary conditions interactions that mimic real-life boundary conditions of the patient. Method as claimed in one of the preceding claims, whereby an orthopedic device (10) is manufactured based on said created manufacturing data (23). Computer program having program code means adapted to perform the method of any one of claims 1 to 12, when the computer program is executed on a data processing unit (20).

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