Nigel Zheng - Academia.edu (original) (raw)
Papers by Nigel Zheng
Bulletin (Hospital for Joint Diseases (New York, N.Y.)), 2006
There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its... more There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its repair. Because they vary in size and shape, it is possible that they could damage the cuff and affect the integrity of the repair. We chose four devices for assessment--SutureLasso (Arthrex, Naples, FL), straight BirdBeak (Arthrex, Naples, FL), Viper (Arthrex, Naples, FL), and a #7 tapered Mayo needle--and performed cuff reattachments in four paired shoulders using suture anchors. These repairs were cycled and tested to failure. The SutureLasso and Mayo needle repairs failed at approximately 285 N whereas the BirdBeak and Viper failed during cycling at 150 N. It appears that the devices, which made the bigger holes in the cuff, can compromise the integrity of the repair.
The influence of the aromatase enzyme in androgen-induced bone maintenance following skeletal-mat... more The influence of the aromatase enzyme in androgen-induced bone maintenance following skeletal-maturity remains somewhat unclear. Our purpose was to determine whether aromatase activity is essential to androgen-induced bone maintenance. 10 month old male Fisher 344 rats (n=73) were randomly assigned to receive Sham surgery, orchiectomy (ORX), ORX+anastrozole (AN; aromatase inhibitor), ORX+testosterone-enanthate (TE, 7.0mg/week), ORX+TE+AN, ORX+trenbolone-enanthate (TREN; non-aromatizable, non-estrogenic testosterone analogue; 1.0mg/week), or ORX+TREN+AN. ORX animals exhibited histomorphometric indices of high-turnover osteopenia and reduced cancellous bone volume compared to Shams. Both TE and TREN administration suppressed cancellous bone turnover similarly and fully prevented ORX-induced cancellous bone loss. TE and TREN treated animals also exhibited greater femoral neck shear strength than ORX animals. AN co-administration slightly inhibited the suppression of bone resorption in ...
Neurology, 2016
Objective: To test the feasibility of using a body-fixed Inertial Measurement Unit (IMU), an elec... more Objective: To test the feasibility of using a body-fixed Inertial Measurement Unit (IMU), an electronic device that measures velocity, acceleration, and change in position, to provide insight into TUG performance in ambALS patients. Background: TUG evaluate mobility, balance, and risk of fall. It record the time required for a participant to stand up from a chair (STS), walk with 180 degree turn (WT), turn before sitting (TS), and sit down (SD). Patients with balance and mobility problems have longer TUG times. How each of the TUG segments relate to the impairment of balance and mobility in ambALS is not known. Methods: Maximum torso flexion/extension angle in degree (MTFEA), Peak Flexion/Peak Extension Angular Velocity (PFAV/PEAV in degrees per second), Peak Vertical Acceleration (PVA in meters per second2), Mean and peak turning angular velocity (MTAV/PTAV) were evaluated in 20 ambALS and 18 ambulatory individuals with Parkinson disease (ambPD) in 2 consecutive TUG tests wearing a...
Skin marker-based motion analysis has been widely used for understanding in vivo locomotion and p... more Skin marker-based motion analysis has been widely used for understanding in vivo locomotion and pathological disorders of human musculoskeletal system in biomechanics research and clinical application. Since the knee joint translation is expressed as the displacement of pre-selected reference point on the femur relative to the tibia local coordinate system (LCS), the translation measurement is highly dependent on the selections of the reference point. In conventional motion analysis, they are often determined based on the marker set, which results in the marker dependent knee translation measurement (MDKT). Unfortunately, the location of bony landmarks which mostly are determined by palpation has limited accuracy and consistency which propagate to poor prediction of knee translation. In this study, we studied the sensitivity of knee translation measurement in response to the selection of different reference points. A marker set-independent approach (MIKT) was developed for the purpo...
Archives of Physical Medicine and Rehabilitation
Gait & Posture
BACKGROUND Wearable sensors have allowed researchers to instrument tests of gait-related mobility... more BACKGROUND Wearable sensors have allowed researchers to instrument tests of gait-related mobility, including the widely used timed 'up-and-go' test (TUG). Currently, there is a lack of instrumented test data on whether children with moderate to severe traumatic brain injury (TBI) perform differently on the TUG compared to typically developed (TD) controls during a cognitive-motor task. RESEARCH QUESTION The aim was to explore the effects of a cognitive-motor task on TUG subcomponents among children with TBI compared to TD children. METHODS This observational cross-sectional study included 12 children with moderate to severe TBI (6 males and 6 females, age 10.5 ± 1.5 years of age) and 10 age and sex-matched TD controls (5 males and 5 females, 10.4 ± 1.3 years of age). Each participant completed 6 trials of the TUG wearing a single inertial measurement unit sensor at a self-selected walking pace while listening to an array of 10 randomly presented single digits during each TUG trial. RESULTS Total time to complete the TUG was not significantly different between groups. The cognitive-motor task led to significantly lower mean turn and peak turn angular velocity values during the turn-around-the-cone and turn-before-sitting TUG subcomponents in children with TBI compared to the TD controls (p ≤ 0.05). Additionally, the cognitive-motor task led to significantly lower values for maximum torso flexion to extension angle, peak flexion and extension angular velocity and peak vertical acceleration for the sit-to-stand subcomponent (p < 0.05). Peak flexion angular velocity during the stand-to-sit subcomponent was lower for the TBI group compared to the children with TD (p < 0.05). SIGNIFICANCE The study provides new insights into the performance of complex gait-related mobility tasks in the context of an instrumented TUG among children with moderate to severe TBI. Our results highlight the potential benefits of outfitting pediatric inpatients with an IMU while completing the TUG.
Gait & Posture
BACKGROUND Studies have evaluated the test-re-test reliability of subcomponents of the timed up a... more BACKGROUND Studies have evaluated the test-re-test reliability of subcomponents of the timed up and-go test in adults by using body-worn inertial sensors. However, studies in children have not been reported in the literature. RESEARCH QUESTION To evaluate the within-session reliability of subcomponents of a newly developed electronically augmented timed 'upand-go' test (EATUG) in ambulatory children with traumatic brain injury (TBI) and children with typical development (TD). METHOD The timed up and go test was administered to twelve consecutive ambulatory children with moderate to severe TBI (6 males and 6 females, age 10.5 ± 1.5 years, range 8-13 years, during inpatient rehabilitation at 27.0 ± 11.8 days following injury) and 10 TD age and sex-matched children (5 males and 5 females, 10.4 ± 1.3 years, range 8-11 years). Participants wore a single chest-mounted inertial measurement sensor package with custom software that measured angular and acceleration velocity and torso flexion and extension angles, while they performed 6 trials of the EATUG test. Measures were derived from the overall time to complete the TUG test, angular velocity and angular displacement data for torso flexion and extension during sit-to-stand and stand-to-sit segments and both mean and peak angular velocities for two turning segments (i.e. turning around a cone and turning-before-sitting). RESULTS Within-session reliability of the subcomponents of the TUG test for children with TBI assessed by the intra-class correlation coefficient was ICC (1,1) = 0.84, (range 0.82-0.96), and for TD children ICC (1,1) = 0.73, (range 0.53-0.89). Scores on Total Time, maximum torso flexion/extension angle and peak flexion angular velocity during sit-tostand, and peak turn angular velocity for both turns around the cone and turns before sitting were lower for children with TBI than for TD children (p ≤ 0.05). SIGNIFICANCE The EATUG test is a reliable measure of physical function in children with TBI who are being discharged from inpatient rehabilitation.
Orthopedics
T he long head of the biceps tendon can be a common cause of shoulder pain. Isolated lesions can ... more T he long head of the biceps tendon can be a common cause of shoulder pain. Isolated lesions can develop from overuse activity, trauma, and the inherent bony anatomy of the intertubercular sulcus, leading to instability. 1,2 Secondary tendinitis can develop in association with impingement syndrome or rotator cuff disease. 2-4 Surgical options for the treatment of biceps pathology include debridement,
Advances in biomechanics and applications
In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-s... more In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-selected reference point (functional center) on each segment determined by the location of anatomical landmarks. However, the placement of skin markers on palpable anatomical landmarks (i.e., femoral epicondyles) has limited reproducibility. Thus, it produces large variances in knee translation measurement among different subjects, as well as across studies. In order improve the repeatability of knee translation measurement, in this study an optimization method was introduced, by which the femoral functional center was numerically determined. At that point the knee anteroposterior translation during the stance phase of walking was minimized. This new method was tested on 30 healthy subjects during walking in gait lab with motion capture system. Using this new method, the impact of skin marker position (at anatomical landmarks) on the knee translation measurement has been minimized. In addition, the ranges of anteroposterior knee translations during stance phase were significantly (p<0.001) smaller than those measured by conventional method which relies on a pre-selected functional center (11.1±3.5 mm vs. 19.9±5.5 mm). The results of anteroposterior translation using this new method were very close to a previously reported knee translation (12.4 mm) from dual fluoroscopic imaging technique. Moreover, this new method increased the reproducibility of knee translation measurement by 50%.
Foot & Ankle Orthopaedics
Journal of tissue engineering and regenerative medicine, Jan 27, 2017
Treatment of tendon-bone junction injuries is a challenge because tendon-bone interface often hea... more Treatment of tendon-bone junction injuries is a challenge because tendon-bone interface often heals poorly and the fibrocartilage zone, which reduces stress concentration, at the interface is not formed. In this study, we used a compound called kartogenin (KGN) with platelet-rich plasma (PRP) to induce the formation of fibrocartilage zone in a rat tendon graft-bone tunnel model. The experimental rats received KGN-PRP or PRP injections in the tendon graft-bone tunnel interface. The control group received saline. After 4, 8 and 12 weeks, Safranin O staining of the tendon graft-bone tunnels revealed abundant proteoglycans in the KGN-PRP group indicating the formation of cartilage-like transition zone. Immunohistochemical and immuno-fluorescence staining revealed collagen types I (Col-I) and II (Col-II) in the newly formed fibrocartilage zone. Both fibrocartilage zone formation and maturation were healing time dependent. In contrast, the PRP and saline control groups had no cartilage-li...
The American Journal of Sports Medicine, 2003
Background: The most common complication of rotator cuff repair is structural failure at the repa... more Background: The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. Hypothesis: A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. Study design: Controlled laboratory study. Methods: Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic rates and loads. The number of cycles to failure, which was defined as a 1-cm gap at the repair site, was then recorded. An arbitrary cut-off point of 5000 cycles was chosen. Results: The mean number of cycles to failure with technique 1 (3694 +/- 1980 cycles) was significantly greater than that with either technique 2 (1414 +/- 1888 cycles) or technique 3 (528 +/- 683 cycles). Failure was predominantly through bone. Conclusions: The initial fixation strength of our double-layer repair exceeds that of isolated single-layer repairs with either suture anchors or transosseous tunnels.
Archives of Physical Medicine and Rehabilitation, 2015
In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-s... more In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-selected reference point (functional center) on each segment determined by the location of anatomical landmarks. However, the placement of skin markers on palpable anatomical landmarks (i.e. femoral epicondyles) has limited reproducibility. Thus, it produces large variances in knee translation measurement among different subjects, as well as across studies. In order improve the repeatability of knee translation measurement, in this study an optimization method was introduced, by which the femoral functional center was numerically determined. At that point the knee anteroposterior translation during the stance phase of walking was minimized. This new method was tested on 30 healthy subjects during walking in gait lab with motion capture system. Using this new method, the impact of skin marker position (at anatomical landmarks) on the knee translation measurement has been minimized. In addi...
Bulletin (Hospital for Joint Diseases (New York, N.Y.)), 2006
There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its... more There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its repair. Because they vary in size and shape, it is possible that they could damage the cuff and affect the integrity of the repair. We chose four devices for assessment--SutureLasso (Arthrex, Naples, FL), straight BirdBeak (Arthrex, Naples, FL), Viper (Arthrex, Naples, FL), and a #7 tapered Mayo needle--and performed cuff reattachments in four paired shoulders using suture anchors. These repairs were cycled and tested to failure. The SutureLasso and Mayo needle repairs failed at approximately 285 N whereas the BirdBeak and Viper failed during cycling at 150 N. It appears that the devices, which made the bigger holes in the cuff, can compromise the integrity of the repair.
The American journal of sports medicine
Athletes at risk for valgus extension overload are also at risk for tears of the anterior bundle ... more Athletes at risk for valgus extension overload are also at risk for tears of the anterior bundle of the ulnar collateral ligament. Some athletes develop ligament tears after procedures for valgus extension overload such as posteromedial olecranon osteotomy. The amount of posteromedial olecranon that can be resected before ulnar collateral ligament strain, and risk of injury, increases is unknown. We dissected and mounted five fresh-frozen human cadaveric elbows to allow strain gauge monitoring of the ulnar collateral ligament with varying valgus stress, elbow flexion angle, and medial osteotomy. The average strain to failure was 11.96%+/-6.51%, corresponding to a load of 347.71+/-46.42 N. The maximum tensile force recorded at failure was 416.24 N. Three-way repeated-measures analysis of variance revealed no significant change in strain with change in the amount of osteotomy for a given applied load and angle of flexion. On the basis of these data, we conclude that the effect of medi...
Physical medicine and rehabilitation clinics of North America, 2000
The development of motion analysis and the application of biomechanical analysis techniques to sp... more The development of motion analysis and the application of biomechanical analysis techniques to sports has paralleled the exponential growth of computational and videographic technology. Technological developments have provided for advances in the investigation of the human body and the action of the human body during sports believed to be unobtainable a few years ago. Technological advancements have brought biomechanical applications into a wide range of fields from orthopedics to entertainment. An area that has made tremendous gains using biomechanics is sports science. Coaches, therapists, and physicians are using biomechanics to improve performance, rehabilitation, and the prevention of sports related injuries. Functional analyses of athletic movements that were impossible a few years ago are available and used today. With new advancements, the possibilities for investigating the way a human interacts and reacts to environmental conditions are ever expanding.
The American journal of sports medicine
The most common complication of rotator cuff repair is structural failure at the repair site. A s... more The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. Controlled laboratory study. Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic ...
ASME 2012 Summer Bioengineering Conference, Parts A and B, 2012
Bulletin (Hospital for Joint Diseases (New York, N.Y.)), 2006
There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its... more There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its repair. Because they vary in size and shape, it is possible that they could damage the cuff and affect the integrity of the repair. We chose four devices for assessment--SutureLasso (Arthrex, Naples, FL), straight BirdBeak (Arthrex, Naples, FL), Viper (Arthrex, Naples, FL), and a #7 tapered Mayo needle--and performed cuff reattachments in four paired shoulders using suture anchors. These repairs were cycled and tested to failure. The SutureLasso and Mayo needle repairs failed at approximately 285 N whereas the BirdBeak and Viper failed during cycling at 150 N. It appears that the devices, which made the bigger holes in the cuff, can compromise the integrity of the repair.
The influence of the aromatase enzyme in androgen-induced bone maintenance following skeletal-mat... more The influence of the aromatase enzyme in androgen-induced bone maintenance following skeletal-maturity remains somewhat unclear. Our purpose was to determine whether aromatase activity is essential to androgen-induced bone maintenance. 10 month old male Fisher 344 rats (n=73) were randomly assigned to receive Sham surgery, orchiectomy (ORX), ORX+anastrozole (AN; aromatase inhibitor), ORX+testosterone-enanthate (TE, 7.0mg/week), ORX+TE+AN, ORX+trenbolone-enanthate (TREN; non-aromatizable, non-estrogenic testosterone analogue; 1.0mg/week), or ORX+TREN+AN. ORX animals exhibited histomorphometric indices of high-turnover osteopenia and reduced cancellous bone volume compared to Shams. Both TE and TREN administration suppressed cancellous bone turnover similarly and fully prevented ORX-induced cancellous bone loss. TE and TREN treated animals also exhibited greater femoral neck shear strength than ORX animals. AN co-administration slightly inhibited the suppression of bone resorption in ...
Neurology, 2016
Objective: To test the feasibility of using a body-fixed Inertial Measurement Unit (IMU), an elec... more Objective: To test the feasibility of using a body-fixed Inertial Measurement Unit (IMU), an electronic device that measures velocity, acceleration, and change in position, to provide insight into TUG performance in ambALS patients. Background: TUG evaluate mobility, balance, and risk of fall. It record the time required for a participant to stand up from a chair (STS), walk with 180 degree turn (WT), turn before sitting (TS), and sit down (SD). Patients with balance and mobility problems have longer TUG times. How each of the TUG segments relate to the impairment of balance and mobility in ambALS is not known. Methods: Maximum torso flexion/extension angle in degree (MTFEA), Peak Flexion/Peak Extension Angular Velocity (PFAV/PEAV in degrees per second), Peak Vertical Acceleration (PVA in meters per second2), Mean and peak turning angular velocity (MTAV/PTAV) were evaluated in 20 ambALS and 18 ambulatory individuals with Parkinson disease (ambPD) in 2 consecutive TUG tests wearing a...
Skin marker-based motion analysis has been widely used for understanding in vivo locomotion and p... more Skin marker-based motion analysis has been widely used for understanding in vivo locomotion and pathological disorders of human musculoskeletal system in biomechanics research and clinical application. Since the knee joint translation is expressed as the displacement of pre-selected reference point on the femur relative to the tibia local coordinate system (LCS), the translation measurement is highly dependent on the selections of the reference point. In conventional motion analysis, they are often determined based on the marker set, which results in the marker dependent knee translation measurement (MDKT). Unfortunately, the location of bony landmarks which mostly are determined by palpation has limited accuracy and consistency which propagate to poor prediction of knee translation. In this study, we studied the sensitivity of knee translation measurement in response to the selection of different reference points. A marker set-independent approach (MIKT) was developed for the purpo...
Archives of Physical Medicine and Rehabilitation
Gait & Posture
BACKGROUND Wearable sensors have allowed researchers to instrument tests of gait-related mobility... more BACKGROUND Wearable sensors have allowed researchers to instrument tests of gait-related mobility, including the widely used timed 'up-and-go' test (TUG). Currently, there is a lack of instrumented test data on whether children with moderate to severe traumatic brain injury (TBI) perform differently on the TUG compared to typically developed (TD) controls during a cognitive-motor task. RESEARCH QUESTION The aim was to explore the effects of a cognitive-motor task on TUG subcomponents among children with TBI compared to TD children. METHODS This observational cross-sectional study included 12 children with moderate to severe TBI (6 males and 6 females, age 10.5 ± 1.5 years of age) and 10 age and sex-matched TD controls (5 males and 5 females, 10.4 ± 1.3 years of age). Each participant completed 6 trials of the TUG wearing a single inertial measurement unit sensor at a self-selected walking pace while listening to an array of 10 randomly presented single digits during each TUG trial. RESULTS Total time to complete the TUG was not significantly different between groups. The cognitive-motor task led to significantly lower mean turn and peak turn angular velocity values during the turn-around-the-cone and turn-before-sitting TUG subcomponents in children with TBI compared to the TD controls (p ≤ 0.05). Additionally, the cognitive-motor task led to significantly lower values for maximum torso flexion to extension angle, peak flexion and extension angular velocity and peak vertical acceleration for the sit-to-stand subcomponent (p < 0.05). Peak flexion angular velocity during the stand-to-sit subcomponent was lower for the TBI group compared to the children with TD (p < 0.05). SIGNIFICANCE The study provides new insights into the performance of complex gait-related mobility tasks in the context of an instrumented TUG among children with moderate to severe TBI. Our results highlight the potential benefits of outfitting pediatric inpatients with an IMU while completing the TUG.
Gait & Posture
BACKGROUND Studies have evaluated the test-re-test reliability of subcomponents of the timed up a... more BACKGROUND Studies have evaluated the test-re-test reliability of subcomponents of the timed up and-go test in adults by using body-worn inertial sensors. However, studies in children have not been reported in the literature. RESEARCH QUESTION To evaluate the within-session reliability of subcomponents of a newly developed electronically augmented timed 'upand-go' test (EATUG) in ambulatory children with traumatic brain injury (TBI) and children with typical development (TD). METHOD The timed up and go test was administered to twelve consecutive ambulatory children with moderate to severe TBI (6 males and 6 females, age 10.5 ± 1.5 years, range 8-13 years, during inpatient rehabilitation at 27.0 ± 11.8 days following injury) and 10 TD age and sex-matched children (5 males and 5 females, 10.4 ± 1.3 years, range 8-11 years). Participants wore a single chest-mounted inertial measurement sensor package with custom software that measured angular and acceleration velocity and torso flexion and extension angles, while they performed 6 trials of the EATUG test. Measures were derived from the overall time to complete the TUG test, angular velocity and angular displacement data for torso flexion and extension during sit-to-stand and stand-to-sit segments and both mean and peak angular velocities for two turning segments (i.e. turning around a cone and turning-before-sitting). RESULTS Within-session reliability of the subcomponents of the TUG test for children with TBI assessed by the intra-class correlation coefficient was ICC (1,1) = 0.84, (range 0.82-0.96), and for TD children ICC (1,1) = 0.73, (range 0.53-0.89). Scores on Total Time, maximum torso flexion/extension angle and peak flexion angular velocity during sit-tostand, and peak turn angular velocity for both turns around the cone and turns before sitting were lower for children with TBI than for TD children (p ≤ 0.05). SIGNIFICANCE The EATUG test is a reliable measure of physical function in children with TBI who are being discharged from inpatient rehabilitation.
Orthopedics
T he long head of the biceps tendon can be a common cause of shoulder pain. Isolated lesions can ... more T he long head of the biceps tendon can be a common cause of shoulder pain. Isolated lesions can develop from overuse activity, trauma, and the inherent bony anatomy of the intertubercular sulcus, leading to instability. 1,2 Secondary tendinitis can develop in association with impingement syndrome or rotator cuff disease. 2-4 Surgical options for the treatment of biceps pathology include debridement,
Advances in biomechanics and applications
In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-s... more In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-selected reference point (functional center) on each segment determined by the location of anatomical landmarks. However, the placement of skin markers on palpable anatomical landmarks (i.e., femoral epicondyles) has limited reproducibility. Thus, it produces large variances in knee translation measurement among different subjects, as well as across studies. In order improve the repeatability of knee translation measurement, in this study an optimization method was introduced, by which the femoral functional center was numerically determined. At that point the knee anteroposterior translation during the stance phase of walking was minimized. This new method was tested on 30 healthy subjects during walking in gait lab with motion capture system. Using this new method, the impact of skin marker position (at anatomical landmarks) on the knee translation measurement has been minimized. In addition, the ranges of anteroposterior knee translations during stance phase were significantly (p<0.001) smaller than those measured by conventional method which relies on a pre-selected functional center (11.1±3.5 mm vs. 19.9±5.5 mm). The results of anteroposterior translation using this new method were very close to a previously reported knee translation (12.4 mm) from dual fluoroscopic imaging technique. Moreover, this new method increased the reproducibility of knee translation measurement by 50%.
Foot & Ankle Orthopaedics
Journal of tissue engineering and regenerative medicine, Jan 27, 2017
Treatment of tendon-bone junction injuries is a challenge because tendon-bone interface often hea... more Treatment of tendon-bone junction injuries is a challenge because tendon-bone interface often heals poorly and the fibrocartilage zone, which reduces stress concentration, at the interface is not formed. In this study, we used a compound called kartogenin (KGN) with platelet-rich plasma (PRP) to induce the formation of fibrocartilage zone in a rat tendon graft-bone tunnel model. The experimental rats received KGN-PRP or PRP injections in the tendon graft-bone tunnel interface. The control group received saline. After 4, 8 and 12 weeks, Safranin O staining of the tendon graft-bone tunnels revealed abundant proteoglycans in the KGN-PRP group indicating the formation of cartilage-like transition zone. Immunohistochemical and immuno-fluorescence staining revealed collagen types I (Col-I) and II (Col-II) in the newly formed fibrocartilage zone. Both fibrocartilage zone formation and maturation were healing time dependent. In contrast, the PRP and saline control groups had no cartilage-li...
The American Journal of Sports Medicine, 2003
Background: The most common complication of rotator cuff repair is structural failure at the repa... more Background: The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. Hypothesis: A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. Study design: Controlled laboratory study. Methods: Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic rates and loads. The number of cycles to failure, which was defined as a 1-cm gap at the repair site, was then recorded. An arbitrary cut-off point of 5000 cycles was chosen. Results: The mean number of cycles to failure with technique 1 (3694 +/- 1980 cycles) was significantly greater than that with either technique 2 (1414 +/- 1888 cycles) or technique 3 (528 +/- 683 cycles). Failure was predominantly through bone. Conclusions: The initial fixation strength of our double-layer repair exceeds that of isolated single-layer repairs with either suture anchors or transosseous tunnels.
Archives of Physical Medicine and Rehabilitation, 2015
In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-s... more In skin-marker based motion analysis, knee translation measurement is highly dependent on a pre-selected reference point (functional center) on each segment determined by the location of anatomical landmarks. However, the placement of skin markers on palpable anatomical landmarks (i.e. femoral epicondyles) has limited reproducibility. Thus, it produces large variances in knee translation measurement among different subjects, as well as across studies. In order improve the repeatability of knee translation measurement, in this study an optimization method was introduced, by which the femoral functional center was numerically determined. At that point the knee anteroposterior translation during the stance phase of walking was minimized. This new method was tested on 30 healthy subjects during walking in gait lab with motion capture system. Using this new method, the impact of skin marker position (at anatomical landmarks) on the knee translation measurement has been minimized. In addi...
Bulletin (Hospital for Joint Diseases (New York, N.Y.)), 2006
There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its... more There are a variety of arthroscopic devices used to pass sutures through the rotator cuff for its repair. Because they vary in size and shape, it is possible that they could damage the cuff and affect the integrity of the repair. We chose four devices for assessment--SutureLasso (Arthrex, Naples, FL), straight BirdBeak (Arthrex, Naples, FL), Viper (Arthrex, Naples, FL), and a #7 tapered Mayo needle--and performed cuff reattachments in four paired shoulders using suture anchors. These repairs were cycled and tested to failure. The SutureLasso and Mayo needle repairs failed at approximately 285 N whereas the BirdBeak and Viper failed during cycling at 150 N. It appears that the devices, which made the bigger holes in the cuff, can compromise the integrity of the repair.
The American journal of sports medicine
Athletes at risk for valgus extension overload are also at risk for tears of the anterior bundle ... more Athletes at risk for valgus extension overload are also at risk for tears of the anterior bundle of the ulnar collateral ligament. Some athletes develop ligament tears after procedures for valgus extension overload such as posteromedial olecranon osteotomy. The amount of posteromedial olecranon that can be resected before ulnar collateral ligament strain, and risk of injury, increases is unknown. We dissected and mounted five fresh-frozen human cadaveric elbows to allow strain gauge monitoring of the ulnar collateral ligament with varying valgus stress, elbow flexion angle, and medial osteotomy. The average strain to failure was 11.96%+/-6.51%, corresponding to a load of 347.71+/-46.42 N. The maximum tensile force recorded at failure was 416.24 N. Three-way repeated-measures analysis of variance revealed no significant change in strain with change in the amount of osteotomy for a given applied load and angle of flexion. On the basis of these data, we conclude that the effect of medi...
Physical medicine and rehabilitation clinics of North America, 2000
The development of motion analysis and the application of biomechanical analysis techniques to sp... more The development of motion analysis and the application of biomechanical analysis techniques to sports has paralleled the exponential growth of computational and videographic technology. Technological developments have provided for advances in the investigation of the human body and the action of the human body during sports believed to be unobtainable a few years ago. Technological advancements have brought biomechanical applications into a wide range of fields from orthopedics to entertainment. An area that has made tremendous gains using biomechanics is sports science. Coaches, therapists, and physicians are using biomechanics to improve performance, rehabilitation, and the prevention of sports related injuries. Functional analyses of athletic movements that were impossible a few years ago are available and used today. With new advancements, the possibilities for investigating the way a human interacts and reacts to environmental conditions are ever expanding.
The American journal of sports medicine
The most common complication of rotator cuff repair is structural failure at the repair site. A s... more The most common complication of rotator cuff repair is structural failure at the repair site. A single-layer repair does not adequately reproduce the anatomic insertion and may not optimize fixation strength. A double-layer rotator cuff repair will have greater initial fixation strength than a single-layer repair. Controlled laboratory study. Twelve fresh-frozen matched pairs of cadaveric shoulders were repaired by using dual-site fixation with both suture anchors and transosseous tunnels on one side (technique 1). Fixation was achieved by using suture anchors with horizontal mattress sutures and bone tunnels with modified Mason-Allen sutures. Half of the contralateral matched shoulders underwent fixation with suture anchors and simple sutures to simulate commonly used arthroscopic methods (technique 2) and, in the rest, fixation was achieved by using transosseous tunnels and modified Mason-Allen sutures (technique 3). Repaired specimens then underwent cyclic loading at physiologic ...
ASME 2012 Summer Bioengineering Conference, Parts A and B, 2012