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Papers by David Beason

Matrix Biology, 2014

Recent studies have demonstrated that the small leucine-rich proteoglycans (SLRPs) biglycan and d... more Recent studies have demonstrated that the small leucine-rich proteoglycans (SLRPs) biglycan and decorin impact tendon development, aging and healing in mature mice. However, despite the increased risk of tendon injury in the elderly, the role of SLRPs in tendon repair has not been investigated in aged animals. Therefore, our objective was to elucidate the influences of bigylcan and decorin on tendon healing in aged mice to relate our findings to previous work in mature mice. Since the processes of aging and healing are known to interact, our hypothesis was that aging mediates the role of biglycan and decorin on tendon healing. Patellar tendons from wildtype, biglycan-null and decorin-null mice were injured at 270 days using an established model. At 3 and 6 weeks post-surgery, structural, mechanical and biochemical analyses were performed and compared to uninjured controls. Early stage healing was inferior in biglycan-null and decorin-null mice as compared to wild type. However, tendons of all genotypes failed to exhibit improved mechanical properties between 3 and 6 weeks post-injury. In contrast, in a previous investigation of tendon healing in mature (i.e., 120 day-old) mice, only biglycan-null mice were deficient in early stage healing while decorin-null − mice were deficient in late-stage healing. These results confirm that the impact of SLRPs on tendon healing is mediated by age and could inform future age-specific therapies for enhancing tendon healing.

The Journal of Knee Surgery

Injuries to the anterolateral ligament (ALL) of the knee are commonly associated with anterior cr... more Injuries to the anterolateral ligament (ALL) of the knee are commonly associated with anterior cruciate ligament (ACL) ruptures. Biomechanical studies have demonstrated conflicting results with regard to the role of the ALL in limiting tibial internal rotation. Clinically, residual pivot shift following ACL reconstruction has been reported to occur up to 25% and has been correlated with poor outcomes. As such, surgical techniques have been developed to enhance rotational stability. Recent biomechanical studies have demonstrated restoration of internal rotational control following ALL reconstruction. The purpose of our study was to understand the biomechanical effects of ACL reconstruction with an ALL internal brace augmentation. We hypothesized that (1) sectioning of the ALL while preserving other lateral extra-articular structures would lead to significant internal rotation laxity and gap formation and (2) ALL repair with internal brace augmentation would lead to reduction in inter...

While useful models have been proposed to predict the mechanical impact of damage in tendon and o... more While useful models have been proposed to predict the mechanical impact of damage in tendon and other soft tissues, the applicability of these models for describing in vivo injury and age-related degeneration has not been investigated. Therefore, the objective of this study was to develop and validate a simple damage model to predict mechanical alterations in mouse patellar tendons after aging, injury, or healing. To characterize baseline properties, uninjured controls at age 150 days were cyclically loaded across three strain levels and five frequencies. For comparison, damage was induced in mature (120 day-old) mice through either injury or aging. Injured mice were sacrificed at three or six weeks after surgery, while aged mice were sacrificed at either 300 or 570 days old. Changes in mechanical properties (relative to baseline) in the three week post-injury group were assessed and used to develop an empirical damage model based on a simple damage parameter related to the equilibr...

Orthopaedic Journal of Sports Medicine

Background: Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of... more Background: Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of LT full-thickness tears, resulting in hip micro- or macroinstability. Graft fixation at the acetabular fossa is critical to achieving the best functional results. Purpose: The purpose of this study is to compare the pullout strength of 2 graft fixation methods used for LT reconstruction of the hip. Study Design: Controlled laboratory study. Methods: In 7 cadaveric specimens, the acetabular socket was prepared after the native LT was transected and the femoral head was removed. Seven separate tibialis anterior grafts were then prepared by suturing a running-locking No. 2 suture on each tail of the graft. Three specimens had fixation of the graft to the acetabulum using an adjustable cortical suspension suture button; the remaining 4 were fixed to the acetabulum using a knotless suture anchor. Specimens were then mounted onto a custom jig within a mechanical test frame to allow for the in...

Arthroscopy, Sports Medicine, and Rehabilitation

Orthopaedic Journal of Sports Medicine

Background: There has been renewed interest in ulnar collateral ligament (UCL) repair in throwing... more Background: There has been renewed interest in ulnar collateral ligament (UCL) repair in throwing athletes because of a greater understanding of UCL injuries, improvement in ligament repair technology, and potentially expedited rehabilitation time and return to play relative to UCL reconstruction. Purpose: To evaluate elbow articular contact and overall joint torque after UCL reconstruction and repair augmented with a collagen-coated fiber tape, InternalBrace. Study Design: Controlled laboratory study. Methods: Ten matched pairs of cadaveric arms (mean age, 41 ± 11 years) were dissected to expose the UCL. Each specimen was secured into a custom test fixture at 90°, and 1 specimen from each pair underwent either a modified Jobe UCL reconstruction or UCL repair with InternalBrace. Each specimen underwent 10 cycles of elbow valgus angular displacement between 0° and 5° at a rate of 1 deg/s in the intact state, after UCL avulsion, and then after UCL reconstruction or repair. Articular c...

Orthopaedic Journal of Sports Medicine

Objectives: Proximal hamstring tendon avulsions are a rare subset of hamstring injuries, and surg... more Objectives: Proximal hamstring tendon avulsions are a rare subset of hamstring injuries, and surgical fixation has become standard, given superior outcomes compared to nonoperative treatment. Open surgical techniques employ a large incision near the gluteal crease and necessitate extensive retraction for optimal visualization, which may increase risk for infection, numbness and potential sciatic nerve injury. Recently described endoscopic repair techniques enable optimal visualization and access to the tendon and ischial tuberosity through several small incisions, potentially reducing risks associated with open repair. Prior cadaveric studies have evaluated biomechanical properties of open repair techniques. The purpose of this study was to compare the biomechanical properties of open and endoscopic suture anchor repair of proximal hamstring ruptures to validate the structural integrity of the endoscopic technique. Methods: Nine fresh-frozen cadaver pelvises (5 M, 4F) were randomly ...

Orthopaedic Journal of Sports Medicine

Background: Suture button fixation of syndesmotic injury is growing in popularity, as it has been... more Background: Suture button fixation of syndesmotic injury is growing in popularity, as it has been shown to provide adequate stability in a more cost-effective manner than screw fixation while allowing more physiologic distal tibiofibular joint motion. However, the optimal repair technique and implant orientation have yet to be determined. Purpose/Hypothesis: The purpose of this study was to biomechanically compare 3 suture button construct configurations/ orientations for syndesmosis fixation: single, parallel, and divergent. The authors hypothesized that all 3 methods would provide adequate stabilization but that the divergent technique would be the most stable. Study Design: Controlled laboratory study. Methods: The fixation strengths of 3 stabilization techniques with suture button devices were compared with 10 cadaveric legs each (N ¼ 30). Ankle motion under cyclic loading was measured in multiple planes: first in the intact state, then following simulated syndesmosis injury, and then following fixation with 1 of 3 randomly assigned constructs-1 suture button, 2 suture buttons in parallel, and 2 divergent suture buttons. Finally, axial loading with external rotation was applied to failure. Results: All syndesmotic fixation methods provided stability to the torn state. There was no statistically significant difference among the 3 fixation techniques in biomechanical stability. Failure most commonly occurred through fibular fracture at supraphysiologic loads. Conclusion: Suture button implant fixation for syndesmotic injury appears to provide stability to the torn syndesmosis, and the configuration of the fixation does not appear to affect the strength or security of the stabilization. Clinical Relevance: This study provides further insight into the biomechanics and optimal configuration of suture button fixation of the torn syndesmosis. Based on these results, the addition of a second suture button may not significantly contribute to immediate postoperative stability.

The American Journal of Sports Medicine

Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weaknes... more Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weakness, and functional limitations. Open surgical repair has been the standard, but improved endoscopic techniques have enabled proximal hamstring fixation with decreased risk of infection and numbness, without the morbidity of a large incision. Purpose/Hypothesis: To (1) describe pertinent anatomy surrounding the proximal hamstring origin in relation to 4 endoscopic portal sites and (2) test for biomechanical differences between open and endoscopic repair. It was hypothesized that (1) endoscopic proximal hamstring repair is efficacious with respect to commonly used portals and (2) there is no biomechanical difference between open and endoscopic techniques. Study Design: Descriptive and controlled laboratory study. Methods: Proximal hamstring ruptures were simulated endoscopically in 10 fresh-frozen human cadaveric pelvis specimens. Endoscopic repair was then completed on 1 limb from each spe...

Orthopaedic journal of sports medicine, 2018

Ulnar collateral ligament (UCL) injuries have increased significantly in recent years, and recons... more Ulnar collateral ligament (UCL) injuries have increased significantly in recent years, and reconstruction has become the preferred treatment for UCL injury over ligament repair. In a recent study, UCL repair with internal bracing demonstrated significantly greater resistance to gap formation in biomechanical tests, even at low cycles of valgus loading. The purpose of this study was to compare the fatigue and failure mechanics of traditional UCL reconstruction with UCL repair and internal bracing. We hypothesized that repaired specimens would have less gap formation, closer return to native gap formation, and greater maximum torque to failure versus traditionally reconstructed specimens. Controlled laboratory study. Ten matched pairs of cadaveric elbows were positioned at 90° of flexion and the native UCL subjected to 500 cycles of subfailure valgus loading. A simulated tear was created, and the 10 cycles were repeated. Each pair of specimens was next given repair with internal braci...

Orthopaedic Journal of Sports Medicine

Objectives: UCL reconstruction has become the preferred treatment for UCL injury in elite thrower... more Objectives: UCL reconstruction has become the preferred treatment for UCL injury in elite throwers desiring a return to throwing. Prior reports of UCL repair demonstrated poor results in professional pitchers, with rate of return to the same or higher level pitching between 0% and 63%. 1,3,6,9,11 However, in young athletes without chronic attritional UCL damage, recent data shows reliable and rapid return to sport with primary UCL repair.2,12,14 We previously introduced a novel UCL repair technique consisting of primary UCL repair, augmented with a spanning tape anchored at either end of the native ligament. Compared to UCL reconstruction, this construct demonstrated significantly greater resistance to gap formation, even at low cycles of valgus loading.8 The purpose of the current study was to compare the high-cycle fatigue mechanics of augmented UCL repair versus modified Jobe UCL reconstruction. We hypothesized that the repaired specimens would have less gap formation compared to...

The Journal of Knee Surgery

Accurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstr... more Accurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstruction. Controversy exists concerning the preferred method of femoral tunnel preparation, with proponents of both medial portal and transtibial drilling techniques. Current ACL literature suggests that placement of the femoral ACL attachment site posterior or “low” in the ACL footprint leads to more anatomically correct ACL mechanics and better rotational control. There is limited literature focusing on ACL graft displacement through knee range of motion based on specific paired placement of femoral and tibial tunnels. Our purpose was to assess ACL isometry between multiple combinations of femoral and tibial tunnels. We hypothesized that placement of the graft at the posterior aspect of the ACL footprint on the femur would be significantly less isometric and lead to more graft displacement as compared with central or anterior placement. The ACL of matched pairs of cadaveric knees was art...

PM&R, 2016

Ultrasound guidance has been proposed as an alternative imaging modality for sacroiliac (SI) join... more Ultrasound guidance has been proposed as an alternative imaging modality for sacroiliac (SI) joint injections. Few studies have been published on the accuracy of this modality for the procedure. The objective of this study was to determine the accuracy of ultrasound-guided SI joint injections using a cadaveric model. Controlled laboratory study. The study was performed in the Skills Laboratory of the American Sports Medicine Institute in St. Vincent's Hospital, Birmingham, AL. Seventeen cadaveric SI joints were injected under ultrasound guidance and dissected to determine the accuracy of intra-articular injections. The presence of intra-articular spread of a white paint marker in the SI joint after ultrasound-guided injection. Of 17 SI joints, 15 (88.2%) were accurately injected intra-articularly. One of the joints with no intra-articular spread was found to be partially frozen at the time of dissection, and the second joint was considered an unsuccessful injection before dissection due to difficulty entering the joint under ultrasound guidance because of marginal osteophytes at the joint line. Of the 15 joints with intra-articular placement, 5 joints (33.3%) showed partial extra-articular spread at the time of initial injection and required redirection of the needle under ultrasound guidance, and 3 joints (20%) had extra-articular spread that was not seen during ultrasound. Ultrasound allowed intra-articular injection in 88.2% of joints in this cadaveric study. Ultrasound does not expose the patient to radiation, as seen with fluoroscopic guidance, which is currently the gold standard for this injection. In addition, ultrasound may allow visualization of extra-articular spread when caused by extra-articular needle placement, which can allow for redirection of the needle to achieve intra-articular injection. IV.

The American journal of sports medicine, Jan 30, 2015

The number of throwing athletes with ulnar collateral ligament (UCL) injuries has increased recen... more The number of throwing athletes with ulnar collateral ligament (UCL) injuries has increased recently, with a seemingly exponential increase of such injuries in adolescents. In cases of acute proximal or distal UCL insertion injuries or in partial-thickness injuries that do not respond to nonoperative management, UCL repair and augmentation rather than reconstruction may be a viable option. The purpose of this study was to biomechanically compare a new technique of augmented UCL repair versus a typical modified Jobe UCL reconstruction technique. The hypotheses were that (1) the repaired specimens would have less gap formation and a higher maximal torque to failure compared with the reconstruction group, and (2) while both groups would show an increase in gap formation after the simulated tear, the repair group would return closer to the native values compared with the reconstruction group. Controlled laboratory study. Nine matched pairs of cadaveric arms were dissected to expose the ...

Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, Jan 25, 2016

Diabetic skin has impaired wound healing properties following injury. We have further shown that ... more Diabetic skin has impaired wound healing properties following injury. We have further shown that diabetic skin has weakened biomechanical properties at baseline. We hypothesize that the biomechanical properties of diabetic skin decline during the progression of the diabetic phenotype, and that this decline is due to the dysregulation of miR-29a, resulting in decreased collagen content. We further hypothesize that treatment with mesenchymal stem cells (MSCs) may improve diabetic wound healing by correction of the dysregulated miR-29a expression. We analyzed the biomechanical properties, collagen gene expression, collagen protein production, and miR-29a levels in skin harvested from 6-18 week old mice during the development of the diabetic phenotype. We also examined the correction of these impairments by both MSC treatment and the inhibition of miR-29a. Diabetic skin demonstrated a progressive impairment of biomechanical properties, decreased collagen content, and increased miR-29a l...

Journal of Orthopaedic Research, 2015

Injury adversely impacts the structure and mechanical properties of a tendon, thus causing pain a... more Injury adversely impacts the structure and mechanical properties of a tendon, thus causing pain and disability. Previously, we demonstrated that patellar tendons in mature (P120) and aged (P300) mice do not recover original functionality, even six weeks after injury, and that uninjured geriatric tendons (P570) are functionally inferior to uninjured mature tendons. In this study, we hypothesized that the repair response in injured geriatric mice would be further compromised, thus undermining patellar tendon function post-injury. Patellar tendons from wild-type mice were injured at 540 days. At 3 and 6 weeks post-surgery, structural, mechanical and biochemical analyses were performed and compared to uninjured controls. Mechanical properties of geriatric tendons failed to improve after injury. When compared to mature and aged tendons post-injury, it was determined that at no age was there a suitable repair response. In previous studies, we were able to associate the absence of SLRPs with phenotypic changes both early and late in repair. Here we found that SLRPs were significantly decreased after injury, thus offering a possible explanation for why geriatric tendons were unable to mount an adequate repair response. Thus, we conclude that regardless of age after maturity, tendon healing ultimately results in a substandard outcome.

Orthopaedic journal of sports medicine, 2014

Advocates of medial portal drilling claim that the transtibial technique results in a more vertic... more Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure. Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling. Controlled laboratory study. Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled i...

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2002

ABSTRACT

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2002

ABSTRACT

Matrix Biology, 2014

Recent studies have demonstrated that the small leucine-rich proteoglycans (SLRPs) biglycan and d... more Recent studies have demonstrated that the small leucine-rich proteoglycans (SLRPs) biglycan and decorin impact tendon development, aging and healing in mature mice. However, despite the increased risk of tendon injury in the elderly, the role of SLRPs in tendon repair has not been investigated in aged animals. Therefore, our objective was to elucidate the influences of bigylcan and decorin on tendon healing in aged mice to relate our findings to previous work in mature mice. Since the processes of aging and healing are known to interact, our hypothesis was that aging mediates the role of biglycan and decorin on tendon healing. Patellar tendons from wildtype, biglycan-null and decorin-null mice were injured at 270 days using an established model. At 3 and 6 weeks post-surgery, structural, mechanical and biochemical analyses were performed and compared to uninjured controls. Early stage healing was inferior in biglycan-null and decorin-null mice as compared to wild type. However, tendons of all genotypes failed to exhibit improved mechanical properties between 3 and 6 weeks post-injury. In contrast, in a previous investigation of tendon healing in mature (i.e., 120 day-old) mice, only biglycan-null mice were deficient in early stage healing while decorin-null − mice were deficient in late-stage healing. These results confirm that the impact of SLRPs on tendon healing is mediated by age and could inform future age-specific therapies for enhancing tendon healing.

The Journal of Knee Surgery

Injuries to the anterolateral ligament (ALL) of the knee are commonly associated with anterior cr... more Injuries to the anterolateral ligament (ALL) of the knee are commonly associated with anterior cruciate ligament (ACL) ruptures. Biomechanical studies have demonstrated conflicting results with regard to the role of the ALL in limiting tibial internal rotation. Clinically, residual pivot shift following ACL reconstruction has been reported to occur up to 25% and has been correlated with poor outcomes. As such, surgical techniques have been developed to enhance rotational stability. Recent biomechanical studies have demonstrated restoration of internal rotational control following ALL reconstruction. The purpose of our study was to understand the biomechanical effects of ACL reconstruction with an ALL internal brace augmentation. We hypothesized that (1) sectioning of the ALL while preserving other lateral extra-articular structures would lead to significant internal rotation laxity and gap formation and (2) ALL repair with internal brace augmentation would lead to reduction in inter...

While useful models have been proposed to predict the mechanical impact of damage in tendon and o... more While useful models have been proposed to predict the mechanical impact of damage in tendon and other soft tissues, the applicability of these models for describing in vivo injury and age-related degeneration has not been investigated. Therefore, the objective of this study was to develop and validate a simple damage model to predict mechanical alterations in mouse patellar tendons after aging, injury, or healing. To characterize baseline properties, uninjured controls at age 150 days were cyclically loaded across three strain levels and five frequencies. For comparison, damage was induced in mature (120 day-old) mice through either injury or aging. Injured mice were sacrificed at three or six weeks after surgery, while aged mice were sacrificed at either 300 or 570 days old. Changes in mechanical properties (relative to baseline) in the three week post-injury group were assessed and used to develop an empirical damage model based on a simple damage parameter related to the equilibr...

Orthopaedic Journal of Sports Medicine

Background: Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of... more Background: Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of LT full-thickness tears, resulting in hip micro- or macroinstability. Graft fixation at the acetabular fossa is critical to achieving the best functional results. Purpose: The purpose of this study is to compare the pullout strength of 2 graft fixation methods used for LT reconstruction of the hip. Study Design: Controlled laboratory study. Methods: In 7 cadaveric specimens, the acetabular socket was prepared after the native LT was transected and the femoral head was removed. Seven separate tibialis anterior grafts were then prepared by suturing a running-locking No. 2 suture on each tail of the graft. Three specimens had fixation of the graft to the acetabulum using an adjustable cortical suspension suture button; the remaining 4 were fixed to the acetabulum using a knotless suture anchor. Specimens were then mounted onto a custom jig within a mechanical test frame to allow for the in...

Arthroscopy, Sports Medicine, and Rehabilitation

Orthopaedic Journal of Sports Medicine

Background: There has been renewed interest in ulnar collateral ligament (UCL) repair in throwing... more Background: There has been renewed interest in ulnar collateral ligament (UCL) repair in throwing athletes because of a greater understanding of UCL injuries, improvement in ligament repair technology, and potentially expedited rehabilitation time and return to play relative to UCL reconstruction. Purpose: To evaluate elbow articular contact and overall joint torque after UCL reconstruction and repair augmented with a collagen-coated fiber tape, InternalBrace. Study Design: Controlled laboratory study. Methods: Ten matched pairs of cadaveric arms (mean age, 41 ± 11 years) were dissected to expose the UCL. Each specimen was secured into a custom test fixture at 90°, and 1 specimen from each pair underwent either a modified Jobe UCL reconstruction or UCL repair with InternalBrace. Each specimen underwent 10 cycles of elbow valgus angular displacement between 0° and 5° at a rate of 1 deg/s in the intact state, after UCL avulsion, and then after UCL reconstruction or repair. Articular c...

Orthopaedic Journal of Sports Medicine

Objectives: Proximal hamstring tendon avulsions are a rare subset of hamstring injuries, and surg... more Objectives: Proximal hamstring tendon avulsions are a rare subset of hamstring injuries, and surgical fixation has become standard, given superior outcomes compared to nonoperative treatment. Open surgical techniques employ a large incision near the gluteal crease and necessitate extensive retraction for optimal visualization, which may increase risk for infection, numbness and potential sciatic nerve injury. Recently described endoscopic repair techniques enable optimal visualization and access to the tendon and ischial tuberosity through several small incisions, potentially reducing risks associated with open repair. Prior cadaveric studies have evaluated biomechanical properties of open repair techniques. The purpose of this study was to compare the biomechanical properties of open and endoscopic suture anchor repair of proximal hamstring ruptures to validate the structural integrity of the endoscopic technique. Methods: Nine fresh-frozen cadaver pelvises (5 M, 4F) were randomly ...

Orthopaedic Journal of Sports Medicine

Background: Suture button fixation of syndesmotic injury is growing in popularity, as it has been... more Background: Suture button fixation of syndesmotic injury is growing in popularity, as it has been shown to provide adequate stability in a more cost-effective manner than screw fixation while allowing more physiologic distal tibiofibular joint motion. However, the optimal repair technique and implant orientation have yet to be determined. Purpose/Hypothesis: The purpose of this study was to biomechanically compare 3 suture button construct configurations/ orientations for syndesmosis fixation: single, parallel, and divergent. The authors hypothesized that all 3 methods would provide adequate stabilization but that the divergent technique would be the most stable. Study Design: Controlled laboratory study. Methods: The fixation strengths of 3 stabilization techniques with suture button devices were compared with 10 cadaveric legs each (N ¼ 30). Ankle motion under cyclic loading was measured in multiple planes: first in the intact state, then following simulated syndesmosis injury, and then following fixation with 1 of 3 randomly assigned constructs-1 suture button, 2 suture buttons in parallel, and 2 divergent suture buttons. Finally, axial loading with external rotation was applied to failure. Results: All syndesmotic fixation methods provided stability to the torn state. There was no statistically significant difference among the 3 fixation techniques in biomechanical stability. Failure most commonly occurred through fibular fracture at supraphysiologic loads. Conclusion: Suture button implant fixation for syndesmotic injury appears to provide stability to the torn syndesmosis, and the configuration of the fixation does not appear to affect the strength or security of the stabilization. Clinical Relevance: This study provides further insight into the biomechanics and optimal configuration of suture button fixation of the torn syndesmosis. Based on these results, the addition of a second suture button may not significantly contribute to immediate postoperative stability.

The American Journal of Sports Medicine

Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weaknes... more Background: Proximal hamstring tendon avulsions are debilitating and commonly cause pain, weakness, and functional limitations. Open surgical repair has been the standard, but improved endoscopic techniques have enabled proximal hamstring fixation with decreased risk of infection and numbness, without the morbidity of a large incision. Purpose/Hypothesis: To (1) describe pertinent anatomy surrounding the proximal hamstring origin in relation to 4 endoscopic portal sites and (2) test for biomechanical differences between open and endoscopic repair. It was hypothesized that (1) endoscopic proximal hamstring repair is efficacious with respect to commonly used portals and (2) there is no biomechanical difference between open and endoscopic techniques. Study Design: Descriptive and controlled laboratory study. Methods: Proximal hamstring ruptures were simulated endoscopically in 10 fresh-frozen human cadaveric pelvis specimens. Endoscopic repair was then completed on 1 limb from each spe...

Orthopaedic journal of sports medicine, 2018

Ulnar collateral ligament (UCL) injuries have increased significantly in recent years, and recons... more Ulnar collateral ligament (UCL) injuries have increased significantly in recent years, and reconstruction has become the preferred treatment for UCL injury over ligament repair. In a recent study, UCL repair with internal bracing demonstrated significantly greater resistance to gap formation in biomechanical tests, even at low cycles of valgus loading. The purpose of this study was to compare the fatigue and failure mechanics of traditional UCL reconstruction with UCL repair and internal bracing. We hypothesized that repaired specimens would have less gap formation, closer return to native gap formation, and greater maximum torque to failure versus traditionally reconstructed specimens. Controlled laboratory study. Ten matched pairs of cadaveric elbows were positioned at 90° of flexion and the native UCL subjected to 500 cycles of subfailure valgus loading. A simulated tear was created, and the 10 cycles were repeated. Each pair of specimens was next given repair with internal braci...

Orthopaedic Journal of Sports Medicine

Objectives: UCL reconstruction has become the preferred treatment for UCL injury in elite thrower... more Objectives: UCL reconstruction has become the preferred treatment for UCL injury in elite throwers desiring a return to throwing. Prior reports of UCL repair demonstrated poor results in professional pitchers, with rate of return to the same or higher level pitching between 0% and 63%. 1,3,6,9,11 However, in young athletes without chronic attritional UCL damage, recent data shows reliable and rapid return to sport with primary UCL repair.2,12,14 We previously introduced a novel UCL repair technique consisting of primary UCL repair, augmented with a spanning tape anchored at either end of the native ligament. Compared to UCL reconstruction, this construct demonstrated significantly greater resistance to gap formation, even at low cycles of valgus loading.8 The purpose of the current study was to compare the high-cycle fatigue mechanics of augmented UCL repair versus modified Jobe UCL reconstruction. We hypothesized that the repaired specimens would have less gap formation compared to...

The Journal of Knee Surgery

Accurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstr... more Accurate tunnel placement is important for a successful anterior cruciate ligament (ACL) reconstruction. Controversy exists concerning the preferred method of femoral tunnel preparation, with proponents of both medial portal and transtibial drilling techniques. Current ACL literature suggests that placement of the femoral ACL attachment site posterior or “low” in the ACL footprint leads to more anatomically correct ACL mechanics and better rotational control. There is limited literature focusing on ACL graft displacement through knee range of motion based on specific paired placement of femoral and tibial tunnels. Our purpose was to assess ACL isometry between multiple combinations of femoral and tibial tunnels. We hypothesized that placement of the graft at the posterior aspect of the ACL footprint on the femur would be significantly less isometric and lead to more graft displacement as compared with central or anterior placement. The ACL of matched pairs of cadaveric knees was art...

PM&R, 2016

Ultrasound guidance has been proposed as an alternative imaging modality for sacroiliac (SI) join... more Ultrasound guidance has been proposed as an alternative imaging modality for sacroiliac (SI) joint injections. Few studies have been published on the accuracy of this modality for the procedure. The objective of this study was to determine the accuracy of ultrasound-guided SI joint injections using a cadaveric model. Controlled laboratory study. The study was performed in the Skills Laboratory of the American Sports Medicine Institute in St. Vincent's Hospital, Birmingham, AL. Seventeen cadaveric SI joints were injected under ultrasound guidance and dissected to determine the accuracy of intra-articular injections. The presence of intra-articular spread of a white paint marker in the SI joint after ultrasound-guided injection. Of 17 SI joints, 15 (88.2%) were accurately injected intra-articularly. One of the joints with no intra-articular spread was found to be partially frozen at the time of dissection, and the second joint was considered an unsuccessful injection before dissection due to difficulty entering the joint under ultrasound guidance because of marginal osteophytes at the joint line. Of the 15 joints with intra-articular placement, 5 joints (33.3%) showed partial extra-articular spread at the time of initial injection and required redirection of the needle under ultrasound guidance, and 3 joints (20%) had extra-articular spread that was not seen during ultrasound. Ultrasound allowed intra-articular injection in 88.2% of joints in this cadaveric study. Ultrasound does not expose the patient to radiation, as seen with fluoroscopic guidance, which is currently the gold standard for this injection. In addition, ultrasound may allow visualization of extra-articular spread when caused by extra-articular needle placement, which can allow for redirection of the needle to achieve intra-articular injection. IV.

The American journal of sports medicine, Jan 30, 2015

The number of throwing athletes with ulnar collateral ligament (UCL) injuries has increased recen... more The number of throwing athletes with ulnar collateral ligament (UCL) injuries has increased recently, with a seemingly exponential increase of such injuries in adolescents. In cases of acute proximal or distal UCL insertion injuries or in partial-thickness injuries that do not respond to nonoperative management, UCL repair and augmentation rather than reconstruction may be a viable option. The purpose of this study was to biomechanically compare a new technique of augmented UCL repair versus a typical modified Jobe UCL reconstruction technique. The hypotheses were that (1) the repaired specimens would have less gap formation and a higher maximal torque to failure compared with the reconstruction group, and (2) while both groups would show an increase in gap formation after the simulated tear, the repair group would return closer to the native values compared with the reconstruction group. Controlled laboratory study. Nine matched pairs of cadaveric arms were dissected to expose the ...

Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, Jan 25, 2016

Diabetic skin has impaired wound healing properties following injury. We have further shown that ... more Diabetic skin has impaired wound healing properties following injury. We have further shown that diabetic skin has weakened biomechanical properties at baseline. We hypothesize that the biomechanical properties of diabetic skin decline during the progression of the diabetic phenotype, and that this decline is due to the dysregulation of miR-29a, resulting in decreased collagen content. We further hypothesize that treatment with mesenchymal stem cells (MSCs) may improve diabetic wound healing by correction of the dysregulated miR-29a expression. We analyzed the biomechanical properties, collagen gene expression, collagen protein production, and miR-29a levels in skin harvested from 6-18 week old mice during the development of the diabetic phenotype. We also examined the correction of these impairments by both MSC treatment and the inhibition of miR-29a. Diabetic skin demonstrated a progressive impairment of biomechanical properties, decreased collagen content, and increased miR-29a l...

Journal of Orthopaedic Research, 2015

Injury adversely impacts the structure and mechanical properties of a tendon, thus causing pain a... more Injury adversely impacts the structure and mechanical properties of a tendon, thus causing pain and disability. Previously, we demonstrated that patellar tendons in mature (P120) and aged (P300) mice do not recover original functionality, even six weeks after injury, and that uninjured geriatric tendons (P570) are functionally inferior to uninjured mature tendons. In this study, we hypothesized that the repair response in injured geriatric mice would be further compromised, thus undermining patellar tendon function post-injury. Patellar tendons from wild-type mice were injured at 540 days. At 3 and 6 weeks post-surgery, structural, mechanical and biochemical analyses were performed and compared to uninjured controls. Mechanical properties of geriatric tendons failed to improve after injury. When compared to mature and aged tendons post-injury, it was determined that at no age was there a suitable repair response. In previous studies, we were able to associate the absence of SLRPs with phenotypic changes both early and late in repair. Here we found that SLRPs were significantly decreased after injury, thus offering a possible explanation for why geriatric tendons were unable to mount an adequate repair response. Thus, we conclude that regardless of age after maturity, tendon healing ultimately results in a substandard outcome.

Orthopaedic journal of sports medicine, 2014

Advocates of medial portal drilling claim that the transtibial technique results in a more vertic... more Advocates of medial portal drilling claim that the transtibial technique results in a more vertical positioning of the graft, which could lead to subsequent failure and/or a residual pivot shift on postoperative examination. However, advocates of transtibial drilling state that with appropriate placement and adequate notchplasty, their technique places the graft in a more anatomically correct position on the wall, negating the resultant potential for pivot shift and early postoperative failure. Transtibial femoral drilling can adequately reproduce the femoral origin of the anterior cruciate ligament (ACL) and place the graft in an anatomical position equivalent to medial portal drilling. Controlled laboratory study. Ten matched-pair cadaveric knees (N = 20) were scanned using computed tomography (CT), and 3-dimensional images of the native ACL origin were reconstructed. The matched pairs were then randomized into transtibial and medial portal groups. The femoral tunnel was drilled i...

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2002

ABSTRACT

Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology, 2002

ABSTRACT