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Papers by Filip Leszko

Journal of Bone and Joint Surgery-british Volume, Mar 1, 2013

Background Kinematics vary, sometimes in important ways, among the different types of total knee ... more Background Kinematics vary, sometimes in important ways, among the different types of total knee arthroplasty (TKA) designs, yet differences between the in vivo mechanisms of cam-post engagement in rotating-platform posterior-stabilized (PS) TKA, bicruciate-stabilized TKA, and fixed-bearing PS TKA designs remain largely uncharacterized. Questions/purposes The objective of this study was to determine the cam-post mechanism interaction for subjects implanted with three different TKA designs. Methods In vivo, analysis was conducted for patients implanted with nine rotating-platform PS TKAs, five knees with a fixed-bearing PS TKA, and 10 knees with a bicruciate-stabilized TKA while performing a deep knee bend. Three-dimensional kinematics of the implant components were determined by analysis of fluoroscopic images during flexion. The distances between the interacting surfaces were measured throughout flexion and instances and locations of contact were identified. Results Seven of the 10 bicruciate-stabilized knees analyzed had the femoral component engaged with the anterior aspect of the tibial post at full extension. Posterior campost engagement occurred at 34°for the bicruciate-stabilized (range, 17°-68°), 93°for the fixed-bearing PS (range, 88°-100°), and at 97°(range, 90°-104°) for rotating-platform PS TKA. In bicruciate-stabilized and fixed-bearing PS knees, the contact initially occurred on the medial aspect of the posterior surface of the tibial post and then moved centrally and superiorly with increasing flexion. For rotating-platform PS TKA, it was located centrally on the posterior surface of the post at all times. Conclusions This study suggests that mobility of the polyethylene might play an important role in ensuring central cam-post interaction in PS TKA. The polyethylene insert rotates axially in accordance with the rotating femur, One of the authors (RDK) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 100,001 to USD 1,000,000 from DePuy Synthese Inc (Warsaw, IN, USA). One of the authors (FL) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 10,001 to USD 100,000 from DePuy Synthese Inc. One of the authors (DAD) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of more than USD 100,001 from DePuy Synthese Inc. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any drug or device prior to clinical use. Each author certifies that his or her institution approved the human protocols for these previous studies, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation was also obtained.

Orthopaedic Proceedings, Sep 1, 2012

Background Kinematics vary, sometimes in important ways, among the different types of total knee ... more Background Kinematics vary, sometimes in important ways, among the different types of total knee arthroplasty (TKA) designs, yet differences between the in vivo mechanisms of cam-post engagement in rotating-platform posterior-stabilized (PS) TKA, bicruciate-stabilized TKA, and fixed-bearing PS TKA designs remain largely uncharacterized. Questions/purposes The objective of this study was to determine the cam-post mechanism interaction for subjects implanted with three different TKA designs. Methods In vivo, analysis was conducted for patients implanted with nine rotating-platform PS TKAs, five knees with a fixed-bearing PS TKA, and 10 knees with a bicruciate-stabilized TKA while performing a deep knee bend. Three-dimensional kinematics of the implant components were determined by analysis of fluoroscopic images during flexion. The distances between the interacting surfaces were measured throughout flexion and instances and locations of contact were identified. Results Seven of the 10 bicruciate-stabilized knees analyzed had the femoral component engaged with the anterior aspect of the tibial post at full extension. Posterior campost engagement occurred at 34°for the bicruciate-stabilized (range, 17°-68°), 93°for the fixed-bearing PS (range, 88°-100°), and at 97°(range, 90°-104°) for rotating-platform PS TKA. In bicruciate-stabilized and fixed-bearing PS knees, the contact initially occurred on the medial aspect of the posterior surface of the tibial post and then moved centrally and superiorly with increasing flexion. For rotating-platform PS TKA, it was located centrally on the posterior surface of the post at all times. Conclusions This study suggests that mobility of the polyethylene might play an important role in ensuring central cam-post interaction in PS TKA. The polyethylene insert rotates axially in accordance with the rotating femur, One of the authors (RDK) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 100,001 to USD 1,000,000 from DePuy Synthese Inc (Warsaw, IN, USA). One of the authors (FL) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 10,001 to USD 100,000 from DePuy Synthese Inc. One of the authors (DAD) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of more than USD 100,001 from DePuy Synthese Inc. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any drug or device prior to clinical use. Each author certifies that his or her institution approved the human protocols for these previous studies, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation was also obtained.

Previous clinical studies have documented the incidence of squeaking in subjects having a ceramic... more Previous clinical studies have documented the incidence of squeaking in subjects having a ceramic-onceramic (COC) THA. An in vivo sound sensor was recently developed used to capture sound at the THA interface. In this first study, it was determined that subjects having all bearing surface types demonstrated variable sounds. Therefore, in this follow-up study, the overall objective was to simultaneously capture in vivo sound and motion of the femoral head within the acetabular cup during weight-bearing activities for subjects implanted with one of four different ceramic-on-ceramic (COC) THA. Twenty subjects, each implanted with one of four types of Ceramic-on-Ceramic THA (9 Smith and Nephew, 8 Stryker, 2 Wright Medical Technologies and 1 Encore) were analyzed under in vivo, weightbearing conditions using video fluoroscopy and a sound sensor while performing gait on a treadmill. Patients were pre-screened and two groups were defined: a group diagnosed as audible squeakers (9 THAs) and...

Introduction: Audible squeaking of hip replacements is an established and observed phenomenon rep... more Introduction: Audible squeaking of hip replacements is an established and observed phenomenon reported as early as the 1950s. Squeaking is often associated with hard-on-hard bearing surfaces, though some noise of polyethylene bearings has also been previously reported. The causes and the conditions of audible hips are not truly understood yet and no known studies have been able to correctly analyze the measured audible effects. Therefore, need of objective research on hip replacements regarding noise sources has become essential. The study objective was to correlate 3D hip kinematics and subsequent audible effects using a sensor device for subjects having a THA under in vivo conditions and to evaluate if separation might be a reason for the undesired sound. Materials and Methods: Post-operative gait kinematics and the related sound of twenty subjects were analyzed under in vivo, weight-bearing conditions using video-fluoroscopy and sound measurement while performing gait on a treadm...

Previously, Komistek et al have demonstrated anomalous behaviours in total joints such as separat... more Previously, Komistek et al have demonstrated anomalous behaviours in total joints such as separation (sliding) in THAs and condylar lift-off in TKAs. These cases result in reduced contact area, increased contact pressure, polyethylene wear and could induce prosthetic loosening and joint instability. However, here is no known research done on correlating kinematic conditions with acoustic data for the tibio-femoral joint interface. This study deals with the development of a new method to diagnose such conditions using sound and frequency data. The objective of this study was to determine and compare the in vivo, 3D kinematics and sound for younger subjects with a normal knee, to those of older subjects, with an unimplanted and implanted knee joint. Ten older subjects having a Hi-Flex PS MB TKA and a contralateral non implanted knee and five younger subjects (with a normal knee) were analysed under in vivo, weight-bearing conditions using video fluoroscopy and a sound sensor while per...

Bone Joint Journal Orthopaedic Proceedings Supplement, Dec 1, 2013

Introduction: Appropriate transverse rotation of the tibial component is critical to achieving a ... more Introduction: Appropriate transverse rotation of the tibial component is critical to achieving a balance of tibial coverage and proper tibio-femoral kinematics in total knee replacement (TKR), yet no consensus exists on the best anatomic references to determine rotation. Historically, surgeons have aligned the tibial component to the medial third of the tibial tubercle 1 , but recent literature suggests this may externally rotate the tibial component relative to the femoral epicondylar axis (ECA) and that the medial border of the tubercle is more reliable 2 . Meanwhile, some TKR components are designed with asymmetry of the tibial tray assuming that maximizing component coverage of the resected tibia will result in proper alignment. The purpose of this study was to determine how different rotational landmarks and natural variation in osteoarthritic patient anatomy may affect asymmetry of the resected tibial plateau. Methods: Pre-operative computed-tomography scans were collected from 14,791 TKR patients. The tibia and femur were segmented and anatomic landmarks identified: tibial mechanical axis, medial third and medial border of the tibial tubercle, PCL attachment site, and the surgical ECA of the femur. Virtual surgery was performed with an 8-mm resection (referencing the high side) made perpendicular to the tibial mechanical axis in the frontal plane, with 3° posterior slope, and transversely aligned with three different landmarks: the ECA, the medial border, and medial third of the tubercle. In each of these rotational alignments, the relative asymmetry of the medial and lateral plateaus was calculated (Medial AP/Lateral AP) (Fig. 1). Results: Rotational alignment of the tibial component to the ECA, medial border, and medial third of the tubercle resulted in progressive external rotation of the tibial tray on the bone. Alignment to the medial border and medial third of the tubercle resulted in average 0.9° ± 5.7° and 7.8° ± 5.3° external rotations of the tray relative to the ECA, respectively (Fig. 2). Greater external rotation of the tibial implant relative to the bone increased the appearance of tibial asymmetry (Fig. 3). Referencing the medial border and medial third of the tubercle resulted in apparent tibial bone asymmetry of 1.10 ± 0.10 and 1.12 ± 0.10, respectively. Discussion: Assuming the ECA is the appropriate rotational reference to re-establish appropriate kinematics 2 , alignment to the medial border of the tubercle resulted in the most favorable tray alignment. However, there was a great deal of variation between the relative position of the ECA and the tubercle across the patient population. Rotational alignment to either the medial border or medial third of the tubercle resulted in external tray alignment relative to the ECA of greater than 3 degrees for 36% and 84% of patients, respectively. In addition, increased tray asymmetry (broader medial plateau) necessitates relative external rotation of the tray on the bone reducing the flexibility of intra-operative rotational adjustment. Tray asymmetry greater than 1.10 (the asymmetry of the resected tibia when aligned to the ECA) may result in external mal-rotation for a significant portion of the patient population.

Revue de Chirurgie Orthopédique et Traumatologique, 2011

Bone Joint Journal Orthopaedic Proceedings Supplement, Dec 1, 2013

Introduction: Adequate coverage of the resected tibial plateau with the tibial tray is necessary ... more Introduction: Adequate coverage of the resected tibial plateau with the tibial tray is necessary to reduce the theoretical risk of tibial subsidence after primary total knee arthroplasty (TKA). Maximizing tibial coverage is balanced against avoiding excessive overhang of the tray causing soft tissue irritation, and establishing proper tray alignment improving implant longevity and patella function 1 . Implant design factors, including the number of tray sizes, tray shape, and tray asymmetry influence the ability to cover the tibial plateau 2 . Furthermore, rotating platform (RP) tray designs decouple restoring proper tibial rotation from maximizing tibial coverage, which may enhance the ability to maximize coverage. The purpose of the current study was to assess the ability of five modern tray designs (Fig. 1), including symmetric, asymmetric, fixed-bearing, and RP designs, to maximize coverage of the tibial plateau across a large patient population. Methods: Lower limb computed-tomography scans were collected from 14,791 TKA patients and the tibia was segmented. Virtual surgery was performed with an 8-mm tibial resection (referencing the high side) made perpendicular to the tibial mechanical axis in the frontal plane, with 3° posterior slope, and aligned transversely to the medial third of the tibial tubercle. An automated algorithm placed the largest possible tray on the plateau, optimizing the ML and AP placement (and I-E rotation for the RP tray), to minimize overhang. The largest sized tray that fit the plateau with less than 2-mm of tray overhang was identified for each of the five implant systems. The surface area of the tibial tray was divided by the area of the resected plateau and the percentage of patients with greater than 85% plateau coverage was calculated. Results: The percentage of patients with greater than 85% plateau coverage across the tray designs ranged from 17.0% to 61.4% (Fig. 1). The tray with the greatest number of size options (Tray 4, 10 sizes) had the best coverage among the fixed-bearing trays. The RP variant of the same tray had the best overall coverage. Tibial asymmetry did not significantly improve the overall tibial coverage across the patient distribution for both asymmetric designs. Incorporating a broader medial condyle improved fit along the posterior medial corner for Tray 2, but increased the average under-hang along the posterior lateral plateau offsetting any improvement in total coverage. Discussion: This analysis represents the most comprehensive assessment of tray coverage to date across a large TKA-patient population. Large variations exist in the size and shape of the proximal tibia among TKA patients 3 . Developing a tray design which provides robust coverage despite this variation remains challenging. This analysis suggests that tibial asymmetry may not robustly improve coverage. Conversely, incorporating an increased number of tray sizes and utilizing an RP implant to decouple coverage from alignment may provide the most reliable solution for maximizing coverage across the patient population.

Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered... more Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered after a TKA surgery. Specifically the implanted patella experiences significantly less rotation than the natural patella. Also, in early flexion, the patellofemoral contact positions differed significantly between implanted and non-implanted patellae. It was also found that some of TKA subjects experience patellofemoral separation. These kinematical differences may lead to adverse mechanical conditions and increase fatigue or cause loosening of the implant components. This study’s objective was to determine the three-dimensional patellofemoral kinematics and correlate it with the in vivo sound (vibrations) detected using accelerometers for subjects having a TKA and a non-implanted knee under in vivo, weight bearing conditions. The correlation of the knee mechanical conditions with the vibration data may indicate new parameters that may be used to diagnose the condition of the articular ...

In one example, a sensor is configured to be implanted into a patient's body. The sensor has ... more In one example, a sensor is configured to be implanted into a patient's body. The sensor has at least one sensing element, a measurement device in communication with the at least one sensing element, and an internal wireless communicator in communication with the measurement device. The at least one sensing element includes a resistor, and the measurement device includes a capacitor. The measurement device measures a discharge time of the capacitor through the resistor so as to generate a measurement value that is proportional to a value of an anatomical property of the anatomical body, such as strain, that is observed by the sensor. The internal wireless communicator wirelessly communicates the measurement value through skin of the patient to an external wireless communicator situated outside of the patient's body.

Journal of Bone Joint Surgery British Volume, Sep 1, 2012

INTRODUCTION Knee simulators are being used to evaluate wear. The current international standards... more INTRODUCTION Knee simulators are being used to evaluate wear. The current international standards have been developed from clinical investigations of the normal knee [1, 2] or from a single TKA patient [3, 4]. However, the forces and motions in a TKA patient differ from a normal knee and, furthermore, the resulting kinematic outcomes after TKA will depend on the design of the device [5]. Consequently, these standard tests may not recreate in-vivo conditions; therefore, the goal of this study was to perform a novel wear simulation using design-specific inputs that have been derived from fluoroscopic images of a deep knee bend. METHODS A wear simulation was developed using fluoroscopic data from a pool of eighteen TKA patients performing a deep knee bend. All patients had a Sigma CR Fixed Bearing implant (DePuy) and were well functioning (Knee Society Score > 90). A single patient was selected that represented the typical motions, which was characterized by early rollback followed by anterior motion with an overall modest internal tibial rotation (Figure 1). The relative motion between the femoral and tibial components was transformed to match the coordinate system of an AMTI knee wear simulator [6] and a compressive load input was derived using inverse dynamics [7]. The resulting force and motions (Figure 2) were then applied in a wear simulation with 5 MRad crosslinked and remelted polyethylene for 3 Mcyc at 1 Hz. Components were carefully positioned and each joint (n=3) was tested in 25% bovine calf serum (Hyclone Laboratories), which was recirculated at 37±2°C [3]. Serum was supplemented with sodium azide and EDTA. Wear was quantified gravimetrically every 0.5 Mcyc using a digital balance (XP250, Mettler-Toledo) with load soak compensation. RESULTS The knee simulator was able to recreate the in-vivo input kinematics. The femoral low point location revealed good agreement between in-vivo and in-vitro conditions and the overall pattern of the motion from full extension to maximum knee flexion was replicated (Figure 3). The measured wear from these inputs was very low (0.7 ± 0.2 mg/Mcyc). DISCUSSION We have performed a device-specific wear simulation for a deep knee bend. Surprisingly, the wear associated with this activity was very low. It is possible that abnormal kinematics, including paradoxical anterior slide and reverse rotation, would generate higher wear. The deviations the between in-vivo and in-vitro kinematics (Figure 3) are likely due to a size mismatch across the transformation process. In a previous study [7] we recreated the in-vivo motions with better fidelity (RMS error = 0.6mm) using size matched components. Further work is needed to improve the transformation technique for different sized components. Also, similar approaches will be used in future investigations to study the effect of abnormal kinematics as well as other designs including rotating platform and cruciate substituting devices.

Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013

IntroductionThe low-cost, no-harm conditions associated with vibroarthography, the study of liste... more IntroductionThe low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment.MethodsThe GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows for comparison of differe...

Journal of Bone and Joint Surgery-british Volume, 2013

Introduction The low-cost, no-harm conditions associated with vibroarthography, the study of list... more Introduction The low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment. Methods The GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows...

In Vivo Determination Of The Mobile Bearing Total Ankle Prosthesis Kinematics Filip Leszko1, Rich... more In Vivo Determination Of The Mobile Bearing Total Ankle Prosthesis Kinematics Filip Leszko1, Richard D. Komistek1, Mohamed R. Mohfouz1, Thierry Judet2, Michel Bonnin3, Jean-Alain Colombier4, Sheldon S. Lin5 1University of Tennessee, Knoxville, TN; 2Hôpital Raymond Poincarré, Garches, France; 3Clinique Saint Anne Lumière, Lyon, France; 4Clinique de l’Union, Toulouse, France; 5North Jersey Orthopaedic Institute, Newmark, NJ fleszko@cmr.utk.edu

Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013

Insall & Scott Surgery of the Knee, 2012

Journal of Bone Joint Surgery British Volume, Sep 1, 2012

Journal of Bone and Joint Surgery-british Volume, Mar 1, 2013

Background Kinematics vary, sometimes in important ways, among the different types of total knee ... more Background Kinematics vary, sometimes in important ways, among the different types of total knee arthroplasty (TKA) designs, yet differences between the in vivo mechanisms of cam-post engagement in rotating-platform posterior-stabilized (PS) TKA, bicruciate-stabilized TKA, and fixed-bearing PS TKA designs remain largely uncharacterized. Questions/purposes The objective of this study was to determine the cam-post mechanism interaction for subjects implanted with three different TKA designs. Methods In vivo, analysis was conducted for patients implanted with nine rotating-platform PS TKAs, five knees with a fixed-bearing PS TKA, and 10 knees with a bicruciate-stabilized TKA while performing a deep knee bend. Three-dimensional kinematics of the implant components were determined by analysis of fluoroscopic images during flexion. The distances between the interacting surfaces were measured throughout flexion and instances and locations of contact were identified. Results Seven of the 10 bicruciate-stabilized knees analyzed had the femoral component engaged with the anterior aspect of the tibial post at full extension. Posterior campost engagement occurred at 34°for the bicruciate-stabilized (range, 17°-68°), 93°for the fixed-bearing PS (range, 88°-100°), and at 97°(range, 90°-104°) for rotating-platform PS TKA. In bicruciate-stabilized and fixed-bearing PS knees, the contact initially occurred on the medial aspect of the posterior surface of the tibial post and then moved centrally and superiorly with increasing flexion. For rotating-platform PS TKA, it was located centrally on the posterior surface of the post at all times. Conclusions This study suggests that mobility of the polyethylene might play an important role in ensuring central cam-post interaction in PS TKA. The polyethylene insert rotates axially in accordance with the rotating femur, One of the authors (RDK) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 100,001 to USD 1,000,000 from DePuy Synthese Inc (Warsaw, IN, USA). One of the authors (FL) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 10,001 to USD 100,000 from DePuy Synthese Inc. One of the authors (DAD) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of more than USD 100,001 from DePuy Synthese Inc. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any drug or device prior to clinical use. Each author certifies that his or her institution approved the human protocols for these previous studies, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation was also obtained.

Orthopaedic Proceedings, Sep 1, 2012

Background Kinematics vary, sometimes in important ways, among the different types of total knee ... more Background Kinematics vary, sometimes in important ways, among the different types of total knee arthroplasty (TKA) designs, yet differences between the in vivo mechanisms of cam-post engagement in rotating-platform posterior-stabilized (PS) TKA, bicruciate-stabilized TKA, and fixed-bearing PS TKA designs remain largely uncharacterized. Questions/purposes The objective of this study was to determine the cam-post mechanism interaction for subjects implanted with three different TKA designs. Methods In vivo, analysis was conducted for patients implanted with nine rotating-platform PS TKAs, five knees with a fixed-bearing PS TKA, and 10 knees with a bicruciate-stabilized TKA while performing a deep knee bend. Three-dimensional kinematics of the implant components were determined by analysis of fluoroscopic images during flexion. The distances between the interacting surfaces were measured throughout flexion and instances and locations of contact were identified. Results Seven of the 10 bicruciate-stabilized knees analyzed had the femoral component engaged with the anterior aspect of the tibial post at full extension. Posterior campost engagement occurred at 34°for the bicruciate-stabilized (range, 17°-68°), 93°for the fixed-bearing PS (range, 88°-100°), and at 97°(range, 90°-104°) for rotating-platform PS TKA. In bicruciate-stabilized and fixed-bearing PS knees, the contact initially occurred on the medial aspect of the posterior surface of the tibial post and then moved centrally and superiorly with increasing flexion. For rotating-platform PS TKA, it was located centrally on the posterior surface of the post at all times. Conclusions This study suggests that mobility of the polyethylene might play an important role in ensuring central cam-post interaction in PS TKA. The polyethylene insert rotates axially in accordance with the rotating femur, One of the authors (RDK) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 100,001 to USD 1,000,000 from DePuy Synthese Inc (Warsaw, IN, USA). One of the authors (FL) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of USD 10,001 to USD 100,000 from DePuy Synthese Inc. One of the authors (DAD) certifies that he or a member of his immediate family has or may receive payments or benefits during this study period of an amount of more than USD 100,001 from DePuy Synthese Inc. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDAapproval status, of any drug or device prior to clinical use. Each author certifies that his or her institution approved the human protocols for these previous studies, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation was also obtained.

Previous clinical studies have documented the incidence of squeaking in subjects having a ceramic... more Previous clinical studies have documented the incidence of squeaking in subjects having a ceramic-onceramic (COC) THA. An in vivo sound sensor was recently developed used to capture sound at the THA interface. In this first study, it was determined that subjects having all bearing surface types demonstrated variable sounds. Therefore, in this follow-up study, the overall objective was to simultaneously capture in vivo sound and motion of the femoral head within the acetabular cup during weight-bearing activities for subjects implanted with one of four different ceramic-on-ceramic (COC) THA. Twenty subjects, each implanted with one of four types of Ceramic-on-Ceramic THA (9 Smith and Nephew, 8 Stryker, 2 Wright Medical Technologies and 1 Encore) were analyzed under in vivo, weightbearing conditions using video fluoroscopy and a sound sensor while performing gait on a treadmill. Patients were pre-screened and two groups were defined: a group diagnosed as audible squeakers (9 THAs) and...

Introduction: Audible squeaking of hip replacements is an established and observed phenomenon rep... more Introduction: Audible squeaking of hip replacements is an established and observed phenomenon reported as early as the 1950s. Squeaking is often associated with hard-on-hard bearing surfaces, though some noise of polyethylene bearings has also been previously reported. The causes and the conditions of audible hips are not truly understood yet and no known studies have been able to correctly analyze the measured audible effects. Therefore, need of objective research on hip replacements regarding noise sources has become essential. The study objective was to correlate 3D hip kinematics and subsequent audible effects using a sensor device for subjects having a THA under in vivo conditions and to evaluate if separation might be a reason for the undesired sound. Materials and Methods: Post-operative gait kinematics and the related sound of twenty subjects were analyzed under in vivo, weight-bearing conditions using video-fluoroscopy and sound measurement while performing gait on a treadm...

Previously, Komistek et al have demonstrated anomalous behaviours in total joints such as separat... more Previously, Komistek et al have demonstrated anomalous behaviours in total joints such as separation (sliding) in THAs and condylar lift-off in TKAs. These cases result in reduced contact area, increased contact pressure, polyethylene wear and could induce prosthetic loosening and joint instability. However, here is no known research done on correlating kinematic conditions with acoustic data for the tibio-femoral joint interface. This study deals with the development of a new method to diagnose such conditions using sound and frequency data. The objective of this study was to determine and compare the in vivo, 3D kinematics and sound for younger subjects with a normal knee, to those of older subjects, with an unimplanted and implanted knee joint. Ten older subjects having a Hi-Flex PS MB TKA and a contralateral non implanted knee and five younger subjects (with a normal knee) were analysed under in vivo, weight-bearing conditions using video fluoroscopy and a sound sensor while per...

Bone Joint Journal Orthopaedic Proceedings Supplement, Dec 1, 2013

Introduction: Appropriate transverse rotation of the tibial component is critical to achieving a ... more Introduction: Appropriate transverse rotation of the tibial component is critical to achieving a balance of tibial coverage and proper tibio-femoral kinematics in total knee replacement (TKR), yet no consensus exists on the best anatomic references to determine rotation. Historically, surgeons have aligned the tibial component to the medial third of the tibial tubercle 1 , but recent literature suggests this may externally rotate the tibial component relative to the femoral epicondylar axis (ECA) and that the medial border of the tubercle is more reliable 2 . Meanwhile, some TKR components are designed with asymmetry of the tibial tray assuming that maximizing component coverage of the resected tibia will result in proper alignment. The purpose of this study was to determine how different rotational landmarks and natural variation in osteoarthritic patient anatomy may affect asymmetry of the resected tibial plateau. Methods: Pre-operative computed-tomography scans were collected from 14,791 TKR patients. The tibia and femur were segmented and anatomic landmarks identified: tibial mechanical axis, medial third and medial border of the tibial tubercle, PCL attachment site, and the surgical ECA of the femur. Virtual surgery was performed with an 8-mm resection (referencing the high side) made perpendicular to the tibial mechanical axis in the frontal plane, with 3° posterior slope, and transversely aligned with three different landmarks: the ECA, the medial border, and medial third of the tubercle. In each of these rotational alignments, the relative asymmetry of the medial and lateral plateaus was calculated (Medial AP/Lateral AP) (Fig. 1). Results: Rotational alignment of the tibial component to the ECA, medial border, and medial third of the tubercle resulted in progressive external rotation of the tibial tray on the bone. Alignment to the medial border and medial third of the tubercle resulted in average 0.9° ± 5.7° and 7.8° ± 5.3° external rotations of the tray relative to the ECA, respectively (Fig. 2). Greater external rotation of the tibial implant relative to the bone increased the appearance of tibial asymmetry (Fig. 3). Referencing the medial border and medial third of the tubercle resulted in apparent tibial bone asymmetry of 1.10 ± 0.10 and 1.12 ± 0.10, respectively. Discussion: Assuming the ECA is the appropriate rotational reference to re-establish appropriate kinematics 2 , alignment to the medial border of the tubercle resulted in the most favorable tray alignment. However, there was a great deal of variation between the relative position of the ECA and the tubercle across the patient population. Rotational alignment to either the medial border or medial third of the tubercle resulted in external tray alignment relative to the ECA of greater than 3 degrees for 36% and 84% of patients, respectively. In addition, increased tray asymmetry (broader medial plateau) necessitates relative external rotation of the tray on the bone reducing the flexibility of intra-operative rotational adjustment. Tray asymmetry greater than 1.10 (the asymmetry of the resected tibia when aligned to the ECA) may result in external mal-rotation for a significant portion of the patient population.

Revue de Chirurgie Orthopédique et Traumatologique, 2011

Bone Joint Journal Orthopaedic Proceedings Supplement, Dec 1, 2013

Introduction: Adequate coverage of the resected tibial plateau with the tibial tray is necessary ... more Introduction: Adequate coverage of the resected tibial plateau with the tibial tray is necessary to reduce the theoretical risk of tibial subsidence after primary total knee arthroplasty (TKA). Maximizing tibial coverage is balanced against avoiding excessive overhang of the tray causing soft tissue irritation, and establishing proper tray alignment improving implant longevity and patella function 1 . Implant design factors, including the number of tray sizes, tray shape, and tray asymmetry influence the ability to cover the tibial plateau 2 . Furthermore, rotating platform (RP) tray designs decouple restoring proper tibial rotation from maximizing tibial coverage, which may enhance the ability to maximize coverage. The purpose of the current study was to assess the ability of five modern tray designs (Fig. 1), including symmetric, asymmetric, fixed-bearing, and RP designs, to maximize coverage of the tibial plateau across a large patient population. Methods: Lower limb computed-tomography scans were collected from 14,791 TKA patients and the tibia was segmented. Virtual surgery was performed with an 8-mm tibial resection (referencing the high side) made perpendicular to the tibial mechanical axis in the frontal plane, with 3° posterior slope, and aligned transversely to the medial third of the tibial tubercle. An automated algorithm placed the largest possible tray on the plateau, optimizing the ML and AP placement (and I-E rotation for the RP tray), to minimize overhang. The largest sized tray that fit the plateau with less than 2-mm of tray overhang was identified for each of the five implant systems. The surface area of the tibial tray was divided by the area of the resected plateau and the percentage of patients with greater than 85% plateau coverage was calculated. Results: The percentage of patients with greater than 85% plateau coverage across the tray designs ranged from 17.0% to 61.4% (Fig. 1). The tray with the greatest number of size options (Tray 4, 10 sizes) had the best coverage among the fixed-bearing trays. The RP variant of the same tray had the best overall coverage. Tibial asymmetry did not significantly improve the overall tibial coverage across the patient distribution for both asymmetric designs. Incorporating a broader medial condyle improved fit along the posterior medial corner for Tray 2, but increased the average under-hang along the posterior lateral plateau offsetting any improvement in total coverage. Discussion: This analysis represents the most comprehensive assessment of tray coverage to date across a large TKA-patient population. Large variations exist in the size and shape of the proximal tibia among TKA patients 3 . Developing a tray design which provides robust coverage despite this variation remains challenging. This analysis suggests that tibial asymmetry may not robustly improve coverage. Conversely, incorporating an increased number of tray sizes and utilizing an RP implant to decouple coverage from alignment may provide the most reliable solution for maximizing coverage across the patient population.

Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered... more Previosuly, Komistek et al. have shown that the kinematics of the patellofemoral joint is altered after a TKA surgery. Specifically the implanted patella experiences significantly less rotation than the natural patella. Also, in early flexion, the patellofemoral contact positions differed significantly between implanted and non-implanted patellae. It was also found that some of TKA subjects experience patellofemoral separation. These kinematical differences may lead to adverse mechanical conditions and increase fatigue or cause loosening of the implant components. This study’s objective was to determine the three-dimensional patellofemoral kinematics and correlate it with the in vivo sound (vibrations) detected using accelerometers for subjects having a TKA and a non-implanted knee under in vivo, weight bearing conditions. The correlation of the knee mechanical conditions with the vibration data may indicate new parameters that may be used to diagnose the condition of the articular ...

In one example, a sensor is configured to be implanted into a patient's body. The sensor has ... more In one example, a sensor is configured to be implanted into a patient's body. The sensor has at least one sensing element, a measurement device in communication with the at least one sensing element, and an internal wireless communicator in communication with the measurement device. The at least one sensing element includes a resistor, and the measurement device includes a capacitor. The measurement device measures a discharge time of the capacitor through the resistor so as to generate a measurement value that is proportional to a value of an anatomical property of the anatomical body, such as strain, that is observed by the sensor. The internal wireless communicator wirelessly communicates the measurement value through skin of the patient to an external wireless communicator situated outside of the patient's body.

Journal of Bone Joint Surgery British Volume, Sep 1, 2012

INTRODUCTION Knee simulators are being used to evaluate wear. The current international standards... more INTRODUCTION Knee simulators are being used to evaluate wear. The current international standards have been developed from clinical investigations of the normal knee [1, 2] or from a single TKA patient [3, 4]. However, the forces and motions in a TKA patient differ from a normal knee and, furthermore, the resulting kinematic outcomes after TKA will depend on the design of the device [5]. Consequently, these standard tests may not recreate in-vivo conditions; therefore, the goal of this study was to perform a novel wear simulation using design-specific inputs that have been derived from fluoroscopic images of a deep knee bend. METHODS A wear simulation was developed using fluoroscopic data from a pool of eighteen TKA patients performing a deep knee bend. All patients had a Sigma CR Fixed Bearing implant (DePuy) and were well functioning (Knee Society Score > 90). A single patient was selected that represented the typical motions, which was characterized by early rollback followed by anterior motion with an overall modest internal tibial rotation (Figure 1). The relative motion between the femoral and tibial components was transformed to match the coordinate system of an AMTI knee wear simulator [6] and a compressive load input was derived using inverse dynamics [7]. The resulting force and motions (Figure 2) were then applied in a wear simulation with 5 MRad crosslinked and remelted polyethylene for 3 Mcyc at 1 Hz. Components were carefully positioned and each joint (n=3) was tested in 25% bovine calf serum (Hyclone Laboratories), which was recirculated at 37±2°C [3]. Serum was supplemented with sodium azide and EDTA. Wear was quantified gravimetrically every 0.5 Mcyc using a digital balance (XP250, Mettler-Toledo) with load soak compensation. RESULTS The knee simulator was able to recreate the in-vivo input kinematics. The femoral low point location revealed good agreement between in-vivo and in-vitro conditions and the overall pattern of the motion from full extension to maximum knee flexion was replicated (Figure 3). The measured wear from these inputs was very low (0.7 ± 0.2 mg/Mcyc). DISCUSSION We have performed a device-specific wear simulation for a deep knee bend. Surprisingly, the wear associated with this activity was very low. It is possible that abnormal kinematics, including paradoxical anterior slide and reverse rotation, would generate higher wear. The deviations the between in-vivo and in-vitro kinematics (Figure 3) are likely due to a size mismatch across the transformation process. In a previous study [7] we recreated the in-vivo motions with better fidelity (RMS error = 0.6mm) using size matched components. Further work is needed to improve the transformation technique for different sized components. Also, similar approaches will be used in future investigations to study the effect of abnormal kinematics as well as other designs including rotating platform and cruciate substituting devices.

Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013

IntroductionThe low-cost, no-harm conditions associated with vibroarthography, the study of liste... more IntroductionThe low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment.MethodsThe GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows for comparison of differe...

Journal of Bone and Joint Surgery-british Volume, 2013

Introduction The low-cost, no-harm conditions associated with vibroarthography, the study of list... more Introduction The low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment. Methods The GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows...

In Vivo Determination Of The Mobile Bearing Total Ankle Prosthesis Kinematics Filip Leszko1, Rich... more In Vivo Determination Of The Mobile Bearing Total Ankle Prosthesis Kinematics Filip Leszko1, Richard D. Komistek1, Mohamed R. Mohfouz1, Thierry Judet2, Michel Bonnin3, Jean-Alain Colombier4, Sheldon S. Lin5 1University of Tennessee, Knoxville, TN; 2Hôpital Raymond Poincarré, Garches, France; 3Clinique Saint Anne Lumière, Lyon, France; 4Clinique de l’Union, Toulouse, France; 5North Jersey Orthopaedic Institute, Newmark, NJ fleszko@cmr.utk.edu

Bone Joint Journal Orthopaedic Proceedings Supplement, Mar 1, 2013

Insall & Scott Surgery of the Knee, 2012

Journal of Bone Joint Surgery British Volume, Sep 1, 2012