Surgical instruments and use thereof

Abstract

The present invention relates to a system for partial or total joint replacement involving two or more bones connected at a joint. The invention includes a measuring jig for accurately marking bone-resection points and a soft-tissue tensioner for assessing and balancing soft tissue around the knee during surgery. The system enables precise intra-operative evaluation of soft-tissue tension and ligament balance, ensuring optimal bone cuts for prosthesis placement. By facilitating accurate alignment and stabilization, the invention enhances joint function and improves post-surgical outcomes, providing both stability and an optimal range of motion for the replaced joint.

Description

[0001] SURGICAL INSTRUMENTS AND USE THEREOF

[0002] FIELD OF INVENTION

[0003] The invention relates to surgical instruments that aid in joint replacement, especially knee replacement procedure - rendering them more accurate and precise. In particular, the invention relates to a system for performing partial or total joint replacement on two or more bones connected at a joint. The present invention also relates to measuring jig to mark bone-resection points and tensioner device for assessing and balancing of soft tissue around the knee. The invention further relates to a method to perform surgery of the knee joint using the aforesaid tools.

[0004] BACKGROUND

[0005] Total Knee Replacement (TKR) is a widely undertaken procedure for degenerative conditions of the knee joint. A recent report suggests that 2,50,000 total knee replacements are undertaken annually in India alone and the numbers are expected to increase. As per rating on the difference made to patients’ ‘quality affected life years’ (QALY), total knee replacement ranks number 3 amongst all types of planned surgical procedures. However, overall 80% of patients achieve full satisfaction with this surgery as compared to over 90% with total hip replacement and cataract surgery that rank numbers 1 and 2 respectively. This is due to a variety of reasons that can be attributed to both surgeon and patient. Apart from issues like correct patient selection for surgery, a major technical development has focused on sub-optimal mechanical alignment of the prosthetic components achieved through surgery. Failure analyses of knee replacements however show that mal- alignment contributes to only a small proportion of failures, that too in the longer term i.e., after 10 years. The majority of cases that require re-do surgery are related to patients experiencing instability or stiffness, which in turn occur due to sub- optimal soft tissue handling during the knee replacements.

[0006] Joint replacement surgery is known in the field and comprises use of artificial joints made of metals, ceramic and / or plastic materials to be secured to the present bones. The knee arthroplasty is well-known surgery to replace a damaged or diseased knee joint with a prosthetic knee joint. Several patent documents relates to inventions directed to devices, tools, methods, software and equipment for joint replacement surgery or particularly knee arthroplasty. The patent document EP2731522B 1 relates to partial knee prosthesis and discloses devices for knee joint replacement with anterior cruciate ligament substitution. Patent No. CA3158786A1 relates to methods and devices for knee surgery with inertial sensors and provides a surgical equipment kit for a knee replacement or revision procedure. Patent Publication No. US20080119938A1 describes knee joint prosthesis for bi-compartmental knee replacement and surgical devices thereof. PCT International Publication No. WO2014209916A1 describes devices, systems and methods for monitoring knee replacements. Another PCT International Publication No. WO2010138854A2 discloses to methods and apparatus for performing knee arthroplasty, such as bicruciate retaining knee arthroplasty.

[0007] Balancing of the soft-tissues and ligaments of the joint during surgery has been given due importance in literature but there has not been instrumentation developed to enable precise objective measurement. The natural knee joint movement is itself quite complex with only six degrees of freedom. Different prostheses have been developed historically in an attempt to naturalise prosthetic knee kinematics but none of them have achieved it. In this scenario, to achieve an optimal result, one must aim not only to achieve perfect alignment but also amalgamate that with proper balancing of the tension in the ligaments and soft tissue in order to restore proper joint stability and range of motion to the knee, post-surgery.

[0008] Methods have been used to map the tibio-femoral axis using CAT scans and tracking of the axis using pins surgically inserted into the bones and using IR cameras or electromagnetic field. The weakest point in this method however remains the surgeon’s skill in marking the bony points on the knee. Driving pins into the bone also leaves them vulnerable to chipping and fracture at a subsequent stage.

[0009] Surgeons have used CT scans and X-rays to pre-operatively obtain the topography of the joint and then super-impose them on the patient’s knee for intra-operative simulation and to accurately make bone cuts as well. When this method of combining image data processed through computer assisted software (CAS) is used in robotic surgery, the accuracy is improved. However, the costs of the equipment and infrastructure makes CAS -guided robotic surgery prohibitively expensive to be adopted widely and thus its benefits are denied to the majority of deserving patients. While the healthcare sector has been touting the benefits of CAS -assisted robotic surgery, in its over-enthusiasm to popularise, it had to resort to cost-cutting measures and basic infection-control often becomes the first casualty. This does not translate to healthy outcomes for the patients.

[0010] The first-generation devices (imageless computer assisted navigation) made for accurate placement of cutting jigs, were prone to errors made by the surgeon in marking the bony points and also to errors in bone-cutting contributed by the play in the cutting instruments. Introduction of image- based intra- operative correlation and robotic-cutting arm for the bones in the second-generation devices has negated both the above errors, though at a significantly higher cost. Soft tissue balancing ability is provided in both the above techniques, but tension measurement as a guide for cutting the bones is not the norm, in sync with prosthesis- specific guides. It is thus imperative that better devices and intervention strategies that are cheaper, yet with comparable efficiencies, need to be developed.

[0011] SUMMARY OF THE INVENTION

[0012] The inventors of the instant invention have, in an attempt to address all the drawbacks of the currently available articular surgical options, developed new implements that provide the surgeon greater accuracy in resecting the joint so as to adapt it for receiving suitable prosthesis components. They also provide the surgeon means for assessing and adjusting the tension of ligaments and soft tissues of the joint during surgery, for better outcomes in terms of stability and greater range of movement.

[0013] The invention comprises a system for partial or total joint replacement performed on two or more bones connected at a joint. The invention also comprises a measuring jig to mark bone-resection points and a tensioner for intra-surgery assessment and adjustment of the soft-tissue tension of an articular joint so that the surgeon is able to obtain functionally better movement for the patient using the prosthesis. The mechanical axis is mapped using both CT scan and MRI readings.

[0014] Conventionally either one of CT scan and MRI readings has been used. The reason for this is that in the arthritic knee at surgery, there are parts where bone is exposed and other parts still covered with cartilage. Since no robotic arm is used, the bone needs to be marked from the surface point in order to place the cutting jig accurately. The mechanical axis is mapped using CT scan and MRI readings as a departure from prevailing practise on the ability to correlate with the bone surface as found intraoperatively. The jig helps the surgeon cut the proximal tibia bone accurately. However, emphasis is laid on soft- tissue tension being optimal for functionally better results for the patient. This is achieved by means of the tensioner device which incorporates means for both sensing intraarticular forces and the relative movements between the opposing bone surfaces. Furthermore it allows for adjustments in the tension so as to equalise the tension on either side of the joint and can work in conjunction with computer software that guides on surgical steps to manipulate the tissues and make further bone cuts to achieve perfect balance. The intra- articular forces can be assessed in real-time during surgery using the tensioner while the mechanical axis is concurrently monitored.

[0015] Based on the type of prosthesis selected and the read-out provided by the tensioner for different positions of the prosthesis, an optimal position wherein the soft-tissue tension is balanced, is chosen and markings for the femoral cuts using the jig is made. The system ensures that these adjustments can be made intra -operatively itself and the patient therefore benefits from a more stable joint fitting with a wider range of movement.

[0016] The invention provides a system for partial or total joint replacement performed on two or more bones connected at a joint. The invention provides two instruments. One instrument is a measuring jig that helps mark the bones where they are to be cut. The second instrument is a 'tissue tensioner” (also referred as “tension measurement device” interchangeably throughout the disclosure) that measures joint gap and soft-tissue tension intra-operatively and provides digital readout for a surgeon to correct bone alignment in real-time and position a suitable prosthesis for that joint.

[0017] The invention integrates measuring and tracking devices with navigation software to enhance surgical precision. It also provides a method for tracking knee alignment and orientation through the joint space during surgery.

[0018] In one of the embodiments, the invention provides a system for performing partial or total joint replacement on two or more bones connected at a joint, wherein the system comprises: a) at least one measuring j ig; b) at least one surgical tool; and c) at least one tension measurement device.

[0019] In another embodiment the invention provides that the system for partial or total joint replacement further comprises at least one navigation system.

[0020] In another embodiment the invention provides that the system for partial or total joint replacement further comprises at least one robotic system.

[0021] In one of the embodiments, the invention provides a measuring jig to mark boneresection points comprising: i) at least one first elongated holding member; ii) at least one second elongated holding member; iii) at least one gripping knob; iv) at least one stop tab; and v) at least one marking tool.

[0022] In an embodiment the invention provides that the first elongated holding member in the measuring jig comprises a proximal end, a distal end and at least one guideway to receive the second elongated holding member.

[0023] In another embodiment the invention provides that the gripping knob in the measuring jig is positioned at proximal end of the first elongated holding member and the stop tab is positioned at distal end of the first elongated holding member.

[0024] In another embodiment the invention provides that the gripping knob in the measuring jig comprises at least one opening for the first elongated holding member and comprises at least one opening for the second elongated holding member.

[0025] In yet another embodiment the invention provides that the first elongated holding member comprises at least one opening adjacent to the stop tab to receive the marking tool.

[0026] In still another embodiment the invention provides that the second elongated holding member comprises at least one opening adjacent to a scale to receive the marking tool.

[0027] In one of the embodiments, the invention provides a measuring jig to mark boneresection points comprising: i) at least one first elongated holding member capable of moving along longitudinal axis and rotating about its perpendicular axis, comprising a proximal end, a distal end and at least one guideway disposed along length of said first elongated holding member to slidably receive at least one second elongated holding member; ii) at least one second elongated holding member capable of slidably traverse in linear direction along the guideway of at least first elongated holding member, comprising a proximal end and a distal end; iii) at least one gripping knob capable of accommodating at least one first elongated holding member and at least one second elongated holding member in a manner such that second elongated holding member is capable of slidably traversing along the guideway of at least first elongated holding member; iv) at least one stop tab comprising scale markings and positioned at distal end of at least one first elongated holding member to guide surgeon for placement of the measuring jig; and v) at least one marking tool positioned at distal end of at least one first elongated holding member and at distal end of at least one second elongated holding member.

[0028] In one of the embodiments, the invention provides a tension measurement device for intra-operative assessment and adjustment of soft-tissue tension and gap of a joint, wherein the device comprises: a. at least one actuator; and b. at least one tiltable stage designed in a manner to tilt an object across one or multiple axes within a limited angular range.

[0029] In one of the embodiments the tension measurement device further comprises at least one knob to control movement of at least one actuator.

[0030] In a further embodiment of the invention the tension measurement device further comprises at least one sensor.

[0031] In a further embodiment of the invention the tension measurement device comprises at least one communication link.

[0032] In a further embodiment the invention provides that in the tension measurement device, the tiltable stage and the actuator of the tension measurement device are positioned over a housing.

[0033] In a still further embodiment of the invention the tension measurement device further comprises at least one window.

[0034] In an embodiment the invention provides a tension measurement device for intraoperative assessment and adjustment of soft-tissue tension and gap of a joint, wherein the device comprises: a) at least one first shaft capable of making movement in one planer direction; and b) at least one second shaft capable of making movement in a direction at an angle to the direction of the first shaft and linked to the first shaft.

[0035] In a further embodiment of the invention the first shaft comprise multiple groves or suitable means for vertical motion.

[0036] In a still further embodiment of the invention the second shaft is further linked to at least one probe or sensor.

[0037] In a yet another embodiment of the invention the first shaft and the second shaft are connected in a rack and pinion arrangement for motion in planes different than plane of motion of first shaft. In an embodiment the invention provides a method for intra-operative tracking and achieving bone alignment and orientation at a joint, wherein the method comprises: i) placing at least one sensor to assess distance between two or more bones and / or force exerted in real time; ii) inserting a tension measurement device of the invention at joint space; iii) conducting horizontal and / or vertical movement of at least one stage or at least one shaft of the tension measurement device; iv) marking bones for cutting by measuring jig of the invention; and v) optionally executing bone cutting followed by placement of prosthesis.

[0038] In an embodiment the invention provides a method of making precise soft-tissue tension and ligament balance in a joint to ensure optimal bone cuts for prosthesis placement, said method comprising: i) inserting at least one probe comprising at least one sensor into joint space, ii) adjusting distance between two or more bones and soft-tissue tension by calibrating a tension measurement device of the invention; iii) marking bones for cutting at the calibrated tension measurement device by measuring jig of the invention; iv) setting factoring the requirements of the make of the prosthesis; and v) cutting bones at the markings to ensure bone alignment and orientation and placement of the prosthesis.

[0039] In another embodiment the invention provides a method for intra-operative monitoring of tissue tension and / or joint-space at a joint to guide bone cutting and prosthesis placement, wherein the method comprises: a) measuring tissue tension and / or alignment in a joint by the tension measuring device of the invention to obtain data in real-time; and b) integrating the data obtained in step a) with at least one navigation system and / or at least one robotic system.

[0040] In an embodiment the invention provides a navigation system for integrating measurements obtained by at least one sensor to provide real-time guidance to surgeon for bone alignment and / or prosthesis placement by the tension measuring device of the invention, wherein the system ensures balanced ligament tension and / or optimal prosthesis alignment throughout range of motion. In an embodiment the invention provides an artificial Intelligence component that provides information during surgery, based on real-time data from the tension measurement device of the invention.

[0041] In an embodiment the invention provides a computer software system for guiding partial or total knee replacement surgery comprising an algorithm that analyses data from a tension measurement device asdescribed herein; and provides real-time information on optimal bone cuts and prosthesis placement based on both kinematic and mechanical alignment principles.

[0042] In an embodiment the invention provides a surgical equipment kit for partial or total joint replacement performed on two or more bones connected at a joint comprising: a) at least one measuring jig; b) at least one surgical tool; and c) at least one tension measurement device.

[0043] In still another embodiment the invention provides method of partial or total joint replacement performed on two or more bones connected at a joint in a subject in need thereof, wherein the method comprises use of at least one of a measuring jig; a tension measurement device; a navigation system; an artificial Intelligence component; and a computer software system and a kit of the present invention.

[0044] In yet another embodiment the invention provides use of a system, a measuring jig; a tension measurement device; a navigation system; an artificial Intelligence component; a computer software system and a kit, in one or more steps of partial or total joint replacement in a subject.

[0045] OBJECTS OF THE INVENTION

[0046] An object of the present invention is to provide devices that are portable and ensure higher accuracy in knee replacement operations.

[0047] Another objective of the invention is to provide cost-efficient devices for articular surgery without compromising on accuracy.

[0048] Another object of the invention is to provide for implements that enable accurate cutting of bones of the knee so as to functionally accommodate prosthesis components.

[0049] Yet another object of the instant invention is to enable dynamic tracking of the articular joint intra-operatively.

[0050] Another object of the invention is to dynamically track and align the tibio-femoral axis pre and post-operatively while avoiding the use of pins on to those bones. Yet another objective is to reorient the registration process to be done after the tibial cut.

[0051] Yet another objective of the invention is to provide a tensioner capable of measuring the gap within the articular joint

[0052] Yet another objective of the invention is to provide dynamic read-out of the forces within the joint.

[0053] Another objective is to provide surgical tools that enable customization of the articular joint to accommodate any prosthesis from a range of prosthetic models and thus cut out surgeon -bi as.

[0054] Another object of the present invention is to enable optimising soft-tissue tension for different prosthesis or for facilitating a range of movement of the knee.

[0055] Yet another objective of the invention is to stage the learning of a surgeon in terms of proficiency in the usage of the surgical devices.

[0056] Another objective of the invention is to assess bone defect and help the surgeon plan for defect-management using the measuring jig software which would provide four- point measurements to make the proximal tibia bone cut.

[0057] Yet another objective is to provide for all three-dimensional accuracy of the tibial cut (in the sagital and axial planes too) by giving a measurement of the tibial slope, so as to enable the surgeon to vary the slope in order to suit different prosthesis designs.

[0058] Another objective is to be able to use the tensioner for revision cases to help plan bone defect management as well as plan constrained or normal polyethylene spacers.

[0059] Yet another objective is to use the tensioner in cases of partial joint replacement (uni-compartmental)

[0060] Yet another objective is to use the software that calibrates from the CT scan in cases of revision surgery where sizes of implant metal augments / cones / sleeves as well as diameters of stems used in complex cases can be planned.

[0061] These and other objectives of the invention will be easily discerned by a person of ordinary skills in the art and will become clearer when reading the detailed description that follows

[0062] BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG. l shows the schematic and diagrammatic representation of the measuring jig.

[0064] FIG 2 shows the deconstructed measuring jig with the First member having a guide along its body. FIG. 3 shows the second member component of the measuring jig.

[0065] FIG. 4 shows the holding knob used to affix the sliding second member into position.

[0066] FIG. 5 shows the C bracket which affixes the measuring jig onto the tibial rod (conventional bone cutting instrument jig).

[0067] FIG. 6 shows the stylus, the pointed tip of which is used to make markings on the bone to be cut.

[0068] FIG. 7 shows the Tensioner with its twin stages mounted on actuators regulated by control knobs.

[0069] FIG. 8 shows front, side, top and isometric views of the Tensioner.

[0070] Fig. 9 shows the front, side, top and isometric views of the support stages of the Tensioner. Fig. 10 shows the front, side and top views of an actuator of the Tensioner.

[0071] Fig. 11 shows side view for Tensioner according to another embodiment of the invention. Fig. 11 A shows supporting stage (I), rack and pinion arrangement for horizontal motion (II) and groves for vertical motion (III). Fig. 11B shows horizontal movement (IV), vertical movement (V) and motor arrangement for vertical motion (VI).

[0072] Fig. 12 shows side view of Tensioner wherein a probe is inserted on both lateral and medial position on knee between joint and distance between bones well as force exerted is digitally read out. Horizontal movement (IV) and vertical movement (V) of the Tensioner are also shown.

[0073] Fig. 13 shows schematic top view to illustrate difference in horizontal movement on the lateral; left side (hl) and medial side; of left side (hl) and right side (h2) of tension provide rotation.

[0074] Fig. 14 shows isometric view of Tensioner to show horizontal movement and vertical movement.

[0075] DETAILED DESCRIPTION

[0076] The invention provides systems, devises, tools, kit and methods for performing partial or total joint replacement on two or more bones connected at joint.

[0077] The system for performing partial or total joint replacement on two or more bones connected at joint comprises at least one measuring jig; at least one surgical tool; and at least one tension measurement device.

[0078] In the system of the present invention, at least one surgical tool may be present for aiding in partial or total joint replacement performed on two or more bones. A person skilled in the art is aware of various surgical tools to be employed for the partial or total joint replacement. Some of the non-limiting examples include surgical pins, surgical knives, surgical saw, surgical drill, retractors, extractors, surgical curettes and osteotomes, rongeurs and graspers along with other useful tools.

[0079] The tibia and femur are hinged together at the tibiofemoral joint, known as the knee joint. The knee joint is held together by numerous ligaments, muscles and tendons. The ligament structure helps control the stability and alignment of the knee. Total knee arthroplasty (“TKA”), involves surgically replacing the ends of the femur and tibia with prosthetic femoral and tibial implants. The surgeon typically affixes two prosthetic components to the patient's bone structure: one prosthetic component to the patient's femur and one prosthetic component to the patient's tibia.

[0080] A total knee arthroplasty (TKA) basic construct consists of a metallic femoral component, a tibial base plate component, an ultra-high-molecular-weight polyethylene (UHMWPE) plastic spacer, and a patellar component. Failure mechanisms in TKA include infection and implant-associated factors, including polyethylene wear, loosening, mal- alignment, and instability. With improvements in polyethylene manufacture, polyethylene wear is no longer a leading cause of failure. Nevertheless, there is a need of improving implant designs and surgical techniques to further ensure longevity of the prosthesis and to avoid technical errors.

[0081] The surgeon may balance the ligament structure across the knee during the surgical procedure to help achieve an efficacious clinical outcome and ensure survival of the knee replacement, e.g., by promoting symmetrical loading forces across the knee. The surgeon may balance with an objective of achieving a balanced flexion — extension gap without medio-lateral laxity or tightness. Accurate soft tissue balancing can contribute to patello-femoral stability, joint alignment, and resulting patient satisfaction. Ligament balancing typically involves placement and sizing of the femoral and tibial components and balancing procedures for the ligaments after cutting the bones.

[0082] The current precision instrumentation in knee replacement surgery is mainly at two levels:

[0083] Computer navigation (imageless): is one of the significant advancements in instrumentation for total knee replacement. It provides surgeons with a precision tool for carrying out the surgery, with the possibility of intraoperative simulation and objective control over various anatomical and surgical parameters and references. Computer Navigation Sensors are implanted on the bone during the operation and dynamically tracked by infra- red cameras or electromagnetic field. The surgeon marks various points on the bones and the system software thereby computes the axis of alignment. Their accuracy is limited by the surgeon’s marking of the bony points on the knee. However, they have the advantage of dynamic tracking that enables assessment of tissue balance during the operation.

[0084] TKR assisted by Robotics (image- based): uses a robotic arm and computerized software to assist the surgeon during the surgery. It provides potential advantages for improvements in radiographic outcomes, reducing the incidence of mechanical axis misalignment of the lower extremity. A pre- operative CT scan derives information about the bone and joint and is correlated with surface marking during the operation so as to enhance the accuracy. Furthermore, there is a robotic arm that makes the cuts on the bone very precisely. Successive systems have been made with the surgeon having greater ability to modulate individual features and also add dynamic testing during movement. However, the infrastructural and maintenance cost puts this technology beyond the reach of most of the deserving patients. Similarly, soft tissue balancing techniques are not improvised using this technology as compared to the previous one.

[0085] The system, devices, tools, methods and / or kit of the present invention can work with equal or improved efficiency with at least one robotic system known in the field. The robotic systems can assist physicians or surgeons in performing medical procedures. Several medical procedures involve localization of a three-dimensional position of a medical instrument within a patient's body in order to provide diagnosis and / or treatment. Articulated robotic arms can be operated under the control of a physician or surgeon, partially autonomously, or completely autonomously to position the medical instrument at the correct location. Due to use of robotic systems, the system, devices, methods and / or kit of the invention may be performed with greater precision providing one or more of the non-limiting advantages of smaller incisions, decreased blood loss and quicker healing time.

[0086] In general, this disclosure is directed to devices and systems for facilitating joint replacement and associated joint replacement techniques. The devices, systems, and techniques of the present disclosure can be used in any partial or total joint replacement procedure performed on two or more bones connected at a joint, including hip replacement surgery, knee replacement surgery, shoulder replacement surgery, elbow replacement surgery, wrist joint replacement, ankle replacement, finger joint replacement, and knuckle joint replacement. In some specific applications, the disclosed devices and techniques are utilized in a total knee replacement surgery. Inventors of the present invention have developed surgical instruments to address the short-comings of the existing interventional approaches. The first instrument is a measuring jig. This can be used together with any standard instrument jig made by any prosthesis-manufacturer and is thus agnostic to design constraints imposed by a given prosthesis. The surgeon obtains image-guided scanning which will include an MRI and CT scan for pre-operative planning. MRI checks the thickness of cartilage but does not give information on the bone anatomy and mechanical alignment. Therefore, the use of both MRI and CT scans goes towards improving the surgeon’s impression of the topography of the joint(s) he has to operate upon. MRI reports and CT scan data is processed by the software to provide measurements to the surgeon for a precise undertaking of bone cuts. The surgeon can then use the measuring jig to mark the positions where cuts are to be made precisely on the tibial plate. This marking system may be used at any given point in the surgical process, e.g., prior to resecting either the tibia or the femur, after resecting one but not both bones, and / or after resecting both bones and installing a prosthetic component on one but not the other bone. The clinician can then insert the resulting assembly in the joint space to make a force measurement at this point in a surgical process.

[0087] The invention combines kinematic and mechanical alignment principles to optimize prosthesis placement, ensuring balanced ligament tension throughout the range of motion.

[0088] The system and devices of the invention monitor tissue tension and joint space during surgery, guiding the surgeon in bone cutting and prosthesis placement.

[0089] This invention provides a precise solution for managing tissue tension and alignment. Tension measurements are taken dynamically during surgery, with the data integrated into navigation software to plan and execute cuts based on real-time soft tissue tension and joint space measurements.

[0090] The advantage of the system and devices resides in enabling intraoperative adjustments, improving surgical outcomes through a more personalized and adaptive approach.

[0091] A tension measurement device, as described in the invention, is designed to measure soft tissue tension and joint-space gap during surgery.

[0092] The invention also provides a navigation system that integrates measurements from at least one sensor to offer real-time guidance to a surgeon for bone cutting and prosthesis placement. The system ensures balanced ligament tension and optimal prosthesis alignment throughout the range of motion.

[0093] The tension measurement device provides digital readings in Newtons and millimeters, allowing for fine calibration and customization for individual patients. It also enables precise control of the knee joint using a tensioner that accommodates additional control surfaces and smaller force increments for more refined manipulation.

[0094] The navigation system is programmed to adapt to different prosthesis designs based on their respective kinematic principles and dimensions, thereby optimizing prosthesis selection and placement. Its adaptability to various prosthetic designs enhances its versatility.

[0095] The present invention also incorporates an Artificial Intelligence (Al) component that provides real-time recommendations to the surgeon for adjustments during surgery, based on data from the tension measurement device.

[0096] Additionally, the invention includes a computer software system for guiding total knee replacement surgery. This system comprises an algorithm that analyzes data from the tension measurement device and provides real-time guidance on optimal bone cuts and prosthesis placement, integrating both kinematic and mechanical alignment principles.

[0097] The computer software system dynamically adjusts the proposed cuts and prosthesis placement based on real-time measurements of soft tissue tension and jointspace gap throughout the surgical procedure.

[0098] The invention, for the first time, introduces a paradigm shift by (i) tracking knee alignment and (ii) determining orientation to knee alignment through the joint space. This provides a much-needed solution to existing systems and devices by offering an optimal combination of kinematic and mechanical alignment concepts in knee replacement / arthroplasty (TKR / TKA).

[0099] Various tensioners have been developed in the field; however, existing trackers are not based on tension measurements. Current advancements, including robotics, involve high setup costs and are primarily based on mechanical alignment.

[0100] Even a basic analysis of knee joint kinematics reveals a complex interplay of multiple factors across three planes.

[0101] A person skilled in the art would recognize that normal knee kinematics vary significantly, meaning that a single pattern of movement cannot define all normal knees. Furthermore, arthritis further alters knee movement, making it challenging to determine the kinematic patterns of arthritic knees and restore them to a single, predefined normal kinematic state.

[0102] The system of the present invention comprises three components:

[0103] (A) Software - for image processing.

[0104] (B) Instrument - for measured alignment cuts.

[0105] (C) Balancer instrument - placed in the joint for tension equalization.

[0106] INSTRUMENT 1 : Measuring Jig

[0107] The measuring jig enhances the accuracy of bone cuts by providing predetermined marking points that are easy for the surgeon to identify during surgery. It eliminates the need for pin tracker insertion into bones, saving time and reducing complications.

[0108] INSTRUMENT 2: Tensioner

[0109] A significant number of knee replacement failures have been attributed to poor soft tissue balance, leading to compromised prosthetic kinematics.

[0110] Traditionally, total knee replacement (TKR) failure or dissatisfaction was thought to result from malalignment. However, advancements in technology have failed to significantly improve clinical outcomes. Among the 20% of TKR patients who remain dissatisfied, various hypotheses have been proposed, often leading to uncertainty and frustration.

[0111] To enhance technical precision, the invention addresses the following unmet needs:

[0112] (a) Shifting soft tissue balance assessment from a subjective to an objective and precise method;

[0113] (b) Enabling intraoperative kinematic evaluation and ensuring optimal kinematics at the completion of the TKR;

[0114] (c) Allowing for variations in TKR procedures to customize the implant placement based on the individual kinematic pattern of the arthritic knee.

[0115] The Tensioner of the invention addresses the three issues mentioned above. Intraoperative evaluation is crucial in significantly improving surgical outcomes, as it allows for real-time adjustments during the procedure.

[0116] The system and Tensioner evaluate the following parameters (with separate arms for the medial and lateral knee compartments; the software correlates data from each arm):

[0117] (a) The extent to which the joint space expands.

[0118] (b) The tension in the individual sides of the knee. (c) The variation in the above two parameters as the knee moves from extension to flexion.

[0119] (d) Sliding motion during knee flexion, which provides insights into femoral rollback.

[0120] (e) Relative movement analysis and correlation, which help determine knee rotation during flexion.

[0121] The construct of the measuring jig is described below:

[0122] Example 1: Measuring jig

[0123] The measuring jig (Fig.1 to Fig. 6) comprises a first elongated holding member (1) having a proximal end and a distal end and a guideway disposed along the length of said first member’s body to slidably receive a second member (2). The proximal end of the first member accommodates a gripping knob (3) and the distal end has a stop tab with scale -markings in millimeters (4). The gripping knob has openings for the second member to slidably traverse in one linear direction. The gripping knob is releasably fastened over a C bracket (5) by means of an interlocking mechanism. This bracket allows for attachment to different types of tibia cutting bone jigs. It further has threaded opening to allow passage of a screw (6) that can run through and extend beyond the body so as to lock the sliding second member in place. Immediately before the stop tab of the first member, is an opening that can firmly receive a stylus for marking (7). The second member too has an elongated body, which can slidably traverse along the guideway of the first member and has proximal and distal ends. The second member has at its distal end an opening adjacent to a scale (8) to firmly receive a stylus (9). The tabs of the first and the second member can be extended to and fixed at different depths as guided by the data from the CT scan. The first holding member can move along the longitudinal axis and rotate about the perpendicular axis. Two of such jigs are attached to each side (medial and lateral aspects of any shin alignment rod respectively). This measuring jig is easily assembled to mark the positions with precision where the bone cuts are to be made. Thus total 4 points of measurement is provided as compared to a single point in the conventional instrument jigs; maximising accuracy using the same standard instrument jigs from the respective prosthesis manufacturer. This instrument is designed to fit into the cutting slots of any of the standard tibia cutting jigs available with the instrument sets provided by the manufacturers of all prosthesis makes. Example 2: Tensioner

[0124] The second surgical-assist device is a tensioner incorporating a soft-tissue and ligament tensioner. The tensioner is able to dynamically assess and adjust the balance of the soft-tissue associated with the operated knee. The tensioner generally has three components, namely, sensors that provide feedback in real-time; actuators that by coordinated movement along their longitudinal axis, can raise or lower sections of the stage which support the joint during surgery and thereby manipulates the tension of the soft tissue; and a communication link that can continuously relay gap distance and tissue tension of the joint in real-time to the surgeon. This is achieved in the form of antenna(e) and sensors communicably-linked to at least one camera and computer monitor. Thus, knee movements, bone alignment, ligament tension and gap dimensions can all be dynamically tracked on the computer screen.

[0125] The tensioner (Fig. 7 to Fig. 10) comprises a sealed housing (10) having sides, a base and a top and a plurality of tiltable stages (11) each having a top surface and a bottom, said stages supported respectively by a plurality of actuators (12) over said housing. There is optionally provided a window (13) on the housing to display the tensile read-out of the soft-tissue. Each actuator has a proximal and a distal end, said each actuator is connected at its proximal end to the top of the housing and at the distal end to the base of the stage. The actuators can elongate and shorten in response to the signal cues. These signal cues may be regulated mechanically through knobs (14) provided on the tensioner, wherein each knob communicates with its actuator or preferably using an external controller which electronically communicates with each actuator independently. The actuator responds to the signal by telescopically shortening or lengthening. The Tensioner has at least one tiltable stage, with its movements controlled by at least one actuator. FIG. 7 shows arrangement of twin-stages in the illustrated tension measuring device. A person skilled in the art would appreciate that a tension measuring device with one or more than two stages would be within the scope of the invention.

[0126] A person skilled in the art would appreciate that the tiltable stage is designed to tilt an object across one or multiple axes within a limited angular range. Thus, the structure, shape, and dimensions of the tiltable stage may vary and can be easily optimized based on the intended joint where at least one bone needs to be aligned and / or at least one prosthesis needs to be placed. In the illustrated tensioner, the tiltable stages roughly contour to the distal femur bone when the device is inserted into the joint gap following the initial tibial bone cut during surgery.

[0127] Load sensors and displacement sensors help monitor the fine movements the joint is subjected to while mounted on the stage. Based on the feedback on the soft -tissue tension, the femur bone cuts are planned in different dimensions - to match with bone alignment (based on the CT and MRI data) as well as tissue release, to be made in conjunction with the bone cutting and avoiding overt focus on either parameter. Specific prosthesis features are also factored in by the software using information such as the thickness of the metal prosthesis etc. to calibrate the bone-resection points. Once the tensioner stages are adjusted for an optimal tonal reading from the soft-tissues, the surgeon can employ the measuring jig to mark the bones for precise cutting. The assembled standard bone cutting jig from the manufacturer can then be used to accomplish femur bone cutting.

[0128] The Tensioner illustrated in Fig. 7 to 10 includes at least one tiltable stage, with movements controlled along both horizontal and vertical axes by at least one actuator. The at least one actuator in turn is controlled by at least one knob. The Tensioner comprise additional components viz. at least one housing and at least on window, a person skilled in the art would appreciate that the window in the Tensioner is for read-out and if the device is wirelessly linked, the display window may not form part of the Tensioner device.

[0129] The present invention also provides another embodiment of the Tensioner (Figs. 11 to 13), in which a probe is inserted between the joint to measure the distance between the bones (femur and tibia in this case) and the force exerted. This measurement can be digitally read, assisting the surgeon in optimally positioning the bones for alignment and achieving soft-tissue balance during the operation. The Tensioner illustrated in Fig. 11 to 14 shows that horizontal movement of one shaft is facilitated by a rack and pinion arrangement, while the movement of the other shaft is driven by a motorized mechanism. In one embodiment, the vertical movement in the Tensioner is rack and pinion; the horizontal movement (measuring roll back of the femur) in the Tensioner is measured while it occurs passively during flexion of the knee, enabled by the forward backward sliding slot in the tilted component of the tensioner.

[0130] The first stage of bone cuts taken will be accurately in the mechanical axis as desired. Unlike the current instrumentation which takes the surgeon through a customized registration process at the start of the operation, the software to compute the resection of the knee joint is designed to do registration at the second stage i.e. after the initial bone cuts and verify the initial bone cut at that time. This would avoid use of bone pins for implantable sensors that additionally reduces the risk of intra-operative fractures (as well as cause thermal injury to the skin when inserted percutaneously thereby leading to wound healing risks and infection along with additional incisions) and also decreases incision length. Thus, by employing the two surgical implements, the surgeon’s precision in cutting the femoral condyle and tibial plate so as to ensure the right-fit for a given prosthesis in the joint as well as allowing for a wider range of movement of the operated knee is enabled. These devices will aid in obtaining better results in articular surgery, especially in total knee replacement surgery.

[0131] The first stage of bone cuts taken will be accurately in the mechanical axis as desired. Unlike the current instrumentation which takes the surgeon through a customized registration process at the start of the operation, the software to compute the resection of the knee joint is designed to do registration at the second stage i.e. after the initial bone cuts and verify the initial bone cut at that time. This would avoid use of bone pins for implantable sensors that additionally reduces the risk of intra-operative fractures (as well as cause thermal injury to the skin when inserted percutaneously thereby leading to wound healing risks and infection along with additional incisions) and also decreases incision length. Thus, by employing the two surgical implements, the surgeon’s precision in cutting the femoral condyle and tibial plate so as to ensure the right-fit for a given prosthesis in the joint as well as allowing for a wider range of movement of the operated knee is enabled. These devices will aid in obtaining better results in articular surgery, especially in total knee replacement surgery.

[0132] The system and devices of the present invention provide the following nonlimiting advantages:

[0133] • Enable precise space and tension measurement, allowing planning based on a combination of mechanical and kinematic alignment.

[0134] • Facilitate planning and execution to achieve optimal kinematics of the resultant prosthesis while adhering to the mechanical axis limitations.

[0135] • Measure both gap (in millimeters) and tension, enabling the navigation software to plan and execute cuts based on the type of prosthesis used.

[0136] • Allow for the selection and use of different prostheses for a specific type of knee, depending on the principle applied to match the respective kinematic pattern. While arthritic pattern classifications exist in literature, precise evaluation methods have been lacking.

[0137] • Pave the way for future knee prostheses with modularity in the desired kinematic aspect.

[0138] • Enable the application of the same principles to other knee procedures, including partial joint replacement.

[0139] • Simplify complex and revision knee replacements by integrating defect and reconstruction planning with real-time computer image simulation for the surgeon.

[0140] • Extend applicability to other joints such as the hip, ankle, and elbow. While the tissue tensions and kinematics differ for these joints, the principles of the invention can be adapted to improve execution in these procedures as well.

[0141] The foregoing provides a description of the preferred embodiments of the present disclosure and the applied technical principles. However, those skilled in the art will appreciate that the protective scope of the present disclosure is not limited to the specific combinations of the technical features described above. The protective scope also extends to other technical solutions formed by any combinations of the above technical features or their equivalents, provided they do not depart from the concept of the present disclosure. This includes, but is not limited to, technical solutions formed by replacing the disclosed features. . .

[0142] Although the subject matter has been described herein with reference to certain embodiments thereof, other embodiments within the scope of the present invention are possible. It will be obvious to those skilled in the art to make various changes, modifications and alterations to the invention described herein. To the extent that these various changes, modifications and alteration do not depart from scope of the present invention, they are intended to be encompassed therein.

Claims

We claim:

1. A system for performing total or partial joint replacement on two or more bones connected at joint, wherein the system comprises: a) at least one measuring jig; b) at least one surgical tool; and c) at least one tension measurement device.

2. The system as claimed in claim 1, further comprising at least one navigation system.

3. The system as claimed in claim 1 or 2, further comprising at least one robotic system.

4. A measuring jig to mark bone -re section points comprising: i) at least one first elongated holding member capable of moving along longitudinal axis and rotating about its perpendicular axis, comprising a proximal end, a distal end and at least one guideway disposed along length of said first elongated holding member to slidably receive at least one second elongated holding member; ii) at least one second elongated holding member capable of slidably traversing in linear direction along the guideway of at least first elongated holding member, comprising a proximal end and a distal end; iii) at least one gripping knob capable of accommodating at least one first elongated holding member and at least one second elongated holding member such that second elongated holding member is capable of slidably traversing along the guideway of at least first elongated holding member; iv) at least one stop tab comprising scale markings and positioned at distal end of at least one first elongated holding member to guide surgeon for placement of the measuring jig; and v) at least one marking tool positioned at distal end of at least one first elongated holding member and at distal end of at least one second elongated holding member.

5. A tension measurement device for intra-operative assessment and adjustment of soft- tissue tension and gap of a joint, wherein the device comprises: a. at least one actuator; and b. at least one tiltable stage designed to tilt an object across one or multiple axes within a limited angular range.

6. The tension measurement device as claimed in claim 5, further comprising at least one knob to control movement of at least one actuator.

7. The tension measurement device as claimed in claim 5 or 6, further comprising at least one sensor.

8. The tension measurement device as claimed in claim 5 to 7, further comprising at least one communication link.

9. The tension measurement device as claimed in any one of claim 5 to 8, wherein the tiltable stage and the actuator are positioned over a housing.

10. The tension measurement device as claimed in any one of claim 5 to 9, further comprising at least one window.

11. A tension measurement device for intra-operative assessment and adjustment of soft- tissue tension and gap of a joint, wherein the device comprises: a) at least one first shaft capable of movement in one planer direction; and b) at least one second shaft capable of movement in a direction at an angle to the direction of the first shaft and linked to the first shaft.

12. The tension measurement device as claimed in claim 11, wherein the first shaft comprises multiple groves or suitable means for vertical motion.

13. The tension measurement device as claimed in claim 11 or 12, wherein the second shaft is further linked to at least one probe or sensor.

14. The tension measurement device as claimed in claim 11 to 13, wherein the first shaft and the second shaft are connected in a rack and pinion arrangement for motion in planes different than plane of motion of first shaft.

15. A method for intra-operative tracking and achieving bone alignment and orientation at a joint, wherein the method comprises: i) placing at least one sensor to assess distance between two or more bones and / or force exerted in real time; ii) inserting a tension measurement device of claims 5 to 14 at joint space;iii) conducting horizontal and / or vertical movement of at least one stage or at least one shaft of the tension measurement device; iv) marking bones for cutting by measuring jig as claimed in claim 4; and v) optionally executing bone cutting followed by placement of prosthesis.

16. A method of making precise soft-tissue tension and ligament balance in a joint to achieve optimal bone cuts for prosthesis placement, said method comprising: i) inserting at least one probe comprising at least one sensor into joint space, ii) adjusting distance between two or more bones and soft-tissue tension by calibrating a tension measurement device as claimed in claims 5 to 14; iii) marking bones for cutting at the calibrated tension measurement device by measuring jig as claimed in claim 4; iv) setting and factoring in the requirements of the make of the prosthesis; and v) cutting bones at the markings to achieve bone alignment and orientation and placement of the prosthesis.

17. A method for intra-operative monitoring of tissue tension and / or joint-space at a joint to guide bone cutting and prosthesis placement, wherein the method comprises: a. measuring tissue tension and / or alignment in a joint by tension measurement device of claims 5 to 14 to obtain data in real-time; and b. integrating the data obtained in step a) with at least one navigation system and / or at least one robotic system.

18. A navigation system for integrating measurements obtained by at least one sensor to provide real-time guidance to surgeon for bone alignment and / or prosthesis placement by tension measurement device of claims 5 to 14, wherein the system ensures balanced ligament tension and / or optimal prosthesis alignment throughout range of motion.

19. An Artificial Intelligence component that provides information intra-operative, based on real-time data from the tension measurement device as claimed in claims 5 to 14.

20. A computer software system for guiding partial or total knee replacement surgery comprising an algorithm that analyses data from a tension measurement device as claimed in claims 5 to 14; and provides real-time information on optimal bone cuts and prosthesis placement based on both kinematic and mechanical alignment principles.

21. A surgical equipment kit for partial or total j oint replacement performed on two or more bones connected at a joint comprising: a) at least one measuring jig; b) at least one surgical tool; and c) at least one tension measurement device.

22. A method of performing partial or total joint replacement on two or more bones connected at a joint in a subject in need thereof, wherein the method comprises use of at least one of a measuring jig as claimed in claim 4; a tension measurement device as claimed in claims 5 to 14; a navigation system as claimed in claim 18; an artificial Intelligence component as claimed in claim 19; and a computer software system as claimed in claim 20 and a kit as claimed in claim 21.

23. Use of a system as claimed claims 1 to 3, a measuring jig as claimed in claim 4; and a tension measurement device as claimed in claims 5 to 14; a navigation system as claimed in claim 18; an artificial Intelligence component as claimed in claim 19; a computer software system as claimed in claim 20 and a kit as claimed in claim 21, in one or more steps of partial or total joint replacement in a subject.

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