Sandeep Mannava - Academia.edu (original) (raw)

Papers by Sandeep Mannava

Research paper thumbnail of Evaluation of in vivo rotator cuff muscle function after acute and chronic detachment of the supraspinatus tendon: an experimental study in an animal model

The Journal of Bone and Joint Surgery

Surgical repair of large chronic rotator cuff tears can be technically demanding because it requi... more Surgical repair of large chronic rotator cuff tears can be technically demanding because it requires manipulation of a muscle-tendon unit that is scarred, retracted, and stiffer than normal, all of which contribute to increased tension at the repair site. The purpose of the present study was to characterize the in vivo rotator cuff muscle-tendon unit function after acute and chronic injury at surgically relevant preload tensions. Sixty-two Sprague-Dawley rats were divided into a healthy, uninjured (control) group (n = 22), an acute injury group (n = 20), and a chronic injury group (n = 20) and underwent in vivo muscle force testing and electromyographic testing of the supraspinatus muscle-tendon unit at various preload tensions. Preload tension affected the maximum supraspinatus muscle contractile force in all groups (p < 0.05). At the peak tension required to repair an acute tear, there was a 28% to 30% reduction in maximum tetanic contraction amplitude in all groups (p < 0.0...

Research paper thumbnail of Rotator cuff injuries in professional and recreational athletes

Journal of surgical orthopaedic advances

Professional and recreational athletes involved in contact sports and sports with repetitive over... more Professional and recreational athletes involved in contact sports and sports with repetitive overhead motion are at increased risk for rotator cuff tears. Shoulder anatomy, pathology, and biomechanics place unique stress on the rotator cuff tendons during sports activity. Athletes demand effective treatment to quickly return to elite competition. A PubMed search assessed treatment options providing expedited recovery time and return to competition. Twelve of 231 articles fit the objective criteria; 90.5% of professional contact athletes, 40% of professional overhead athletes, and 83.3% of recreational athletes fully recovered following rotator cuff tear surgical repair. Prompt surgical treatment for full-thickness rotator cuff tears may be appropriate for contact athletes and recreational overhead athletes. Although professional overhead athletes have low recovery rates, surgical repair of full-thickness rotator cuff tears may still be indicated. The authors propose a treatment algo...

Research paper thumbnail of Randomized Comparison of Volar Locking Plates and Intramedullary Nails for Unstable Distal Radius Fractures

The Journal of Hand Surgery, 2015

To compare minimally invasive intramedullary nails (IMN) and volar locking plates (VLP) for the t... more To compare minimally invasive intramedullary nails (IMN) and volar locking plates (VLP) for the treatment of unstable distal radius fractures by evaluating postoperative subjective, radiographic, and functional outcomes. The hypothesis was that IMN patients would have less pain and required less pain medication in the early postoperative period and returned to work earlier than VLP patients. Sixty patients with closed, displaced, unstable, extra-articular, metaphyseal fractures of the distal radius were randomized to receive a VLP or an IMN for internal fixation. Functional outcomes (Quick Disabilities of the Arm, Shoulder, and Hand, Michigan Hand Questionnaire), radiographic measurements (ulnar variance, radial height, inclination, and volar tilt), and range of motion were assessed until final follow-up at 2 years after surgery. Narcotic pain medication use was documented for 5 weeks following surgery. There were 2 groups of 30 patients with IMN (mean age, 55 ± 14 y) or VLP (mean age, 55 ± 16 y) with similar demographics and comorbidities. Patients with IMN regained extension earlier but had similar range of motion to patients with VLP at final follow-up. There was similar improvement in Michigan Hand Questionnaire, Quick Disabilities of the Arm, Shoulder, and Hand, and strength between groups. Five weeks after surgery, fewer IMN patients required narcotic pain medication (13%) than VLP patients (33%). Radiographic outcomes were similar at final follow-up. There were 3 failures with IMN versus 1 failure with VLP. All 10 employed patients with IMN returned to previous work compared with 10 of the 12 employed patients with VLP. Time to return to work was similar for both groups. In a cohort of similar patients, IMN and VLP provided comparable improvement in functional and radiographic outcomes. Patients with IMN required less narcotic pain medication after surgery than VLP patients. Therapeutic II.

Research paper thumbnail of Robotic systems in orthopaedic surgery

The Journal of bone and joint surgery. British volume, 2011

Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate r... more Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate robotic technology in 1992, with the introduction of ROBODOC, for the planning and performance of total hip replacement. The use of robotic systems has subsequently increased, with promising short-term radiological outcomes when compared with traditional orthopaedic procedures. Robotic systems can be classified into two categories: autonomous and haptic (or surgeon-guided). Passive surgery systems, which represent a third type of technology, have also been adopted recently by orthopaedic surgeons. While autonomous systems have fallen out of favour, tactile systems with technological improvements have become widely used. Specifically, the use of tactile and passive robotic systems in unicompartmental knee replacement (UKR) has addressed some of the historical mechanisms of failure of non-robotic UKR. These systems assist with increasing the accuracy of the alignment of the components and p...

Research paper thumbnail of Achieving accurate ligament balancing using robotic-assisted unicompartmental knee arthroplasty

Advances in orthopedics, 2013

Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients w... more Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients with limited disease. However, UKA is technically challenging and relies on accurate component positioning and restoration of natural knee kinematics. This study examined the accuracy of dynamic, real-time ligament balancing using a robotic-assisted UKA system. Surgical data obtained from the computer system were prospectively collected from 51 patients (52 knees) undergoing robotic-assisted medial UKA by a single surgeon. Dynamic ligament balancing of the knee was obtained under valgus stress prior to component implantation and then compared to final ligament balance with the components in place. Ligament balancing was accurate up to 0.53 mm compared to the preoperative plan, with 83% of cases within 1 mm at 0°, 30°, 60°, 90°, and 110° of flexion. Ligamentous laxity of 1.31 ± 0.13 mm at 30° of flexion was corrected successfully to 0.78 ± 0.17 mm (P < 0.05). Robotic-assisted UKA allows...

Research paper thumbnail of Tissue-Engineered Approach to Tendon and Ligament Reconstruction: Current Trends

Research paper thumbnail of Arthroscopic Treatment of Bucket-Handle Labral Tear and Acetabular Fracture

Arthroscopy Techniques, 2014

Traumatic hip dislocations are associated with chondral and labral pathology as well as loose bod... more Traumatic hip dislocations are associated with chondral and labral pathology as well as loose bodies that can be incarcerated in the joint. These types of injury often lead to traumatic arthritis. In some cases an osseo-labral fragment may become incarcerated in the joint that is not readily visualized preoperatively. In place of open surgery, hip arthroscopy permits a technique to remove loose bodies and repair labral tears to restore joint congruity and achieve fracture reduction and fixation.

Research paper thumbnail of Injury Mechanisms of Several Common Sports-Related Orthopaedic Injuries

Orthopaedic Biomechanics, 2012

Research paper thumbnail of A Tissue-Engineered Approach to Tendon and Ligament Reconstruction

Research paper thumbnail of Type-1 pericytes accumulate after tissue injury and produce collagen in an organ-dependent manner

Stem Cell Research & Therapy, 2014

Introduction: Fibrosis, or scar formation, is a pathological condition characterized by excessive... more Introduction: Fibrosis, or scar formation, is a pathological condition characterized by excessive production and accumulation of collagen, loss of tissue architecture, and organ failure in response to uncontrolled wound healing. Several cellular populations have been implicated, including bone marrow-derived circulating fibrocytes, endothelial cells, resident fibroblasts, epithelial cells, and recently, perivascular cells called pericytes. We previously demonstrated pericyte functional heterogeneity in skeletal muscle. Whether pericyte subtypes are present in other tissues and whether a specific pericyte subset contributes to organ fibrosis are unknown. Methods: Here, we report the presence of two pericyte subtypes, type-1 (Nestin-GFP-/NG2-DsRed+) and type-2 (Nestin-GFP+/NG2-DsRed+), surrounding blood vessels in lungs, kidneys, heart, spinal cord, and brain. Using Nestin-GFP/NG2-DsRed transgenic mice, we induced pulmonary, renal, cardiac, spinal cord, and cortical injuries to investigate the contributions of pericyte subtypes to fibrous tissue formation in vivo.

Research paper thumbnail of A Human Hair Keratin Hydrogel Scaffold Enhances Median Nerve Regeneration in Nonhuman Primates: An Electrophysiological and Histological Study

Tissue Engineering Part A, 2013

A human hair keratin biomaterial hydrogel scaffold was evaluated as a nerve conduit luminal fille... more A human hair keratin biomaterial hydrogel scaffold was evaluated as a nerve conduit luminal filler following median nerve transection injury in 10 Macaca fascicularis nonhuman primates (NHP). A 1 cm nerve gap was grafted with a NeuraGen Ò collagen conduit filled with either saline or keratin hydrogel and nerve regeneration was evaluated by electrophysiology for a period of 12 months. The keratin hydrogel-grafted nerves showed significant improvement in return of compound motor action potential (CMAP) latency and recovery of baseline nerve conduction velocity (NCV) compared with the saline-treated nerves. Histological evaluation was performed on retrieved median nerves and abductor pollicis brevis (APB) muscles at 12 months. Nerve histomorphometry showed a significantly larger nerve area in the keratin group compared with the saline group and the keratin APB muscles had a significantly higher myofiber density than the saline group. This is the first published study to show that an acellular biomaterial hydrogel conduit filler can be used to enhance peripheral nerve regeneration and motor recovery in an NHP model.

Research paper thumbnail of The science of rotator cuff tears: translating animal models to clinical recommendations using simulation analysis

Knee Surgery, Sports Traumatology, Arthroscopy, 2012

The purpose of this article is to review basic science studies using various animal models for ro... more The purpose of this article is to review basic science studies using various animal models for rotator cuff research and to describe structural, biomechanical, and functional changes to muscle following rotator cuff tears. The use of computational simulations to translate the findings from animal models to human scale is further detailed. A comprehensive review was performed of the basic science literature describing the use of animal models and simulation analysis to examine muscle function following rotator cuff injury and repair in the ageing population. The findings from various studies of rotator cuff pathology emphasize the importance of preventing permanent muscular changes with detrimental results. In vivo muscle function, electromyography, and passive muscle-tendon unit properties were studied before and after supraspinatus tenotomy in a rodent rotator cuff injury model (acute vs chronic). Then, a series of simulation experiments were conducted using a validated computational human musculoskeletal shoulder model to assess both passive and active tension of rotator cuff repairs based on surgical positioning. Outcomes of rotator cuff repair may be improved by earlier surgical intervention, with lower surgical repair tensions and fewer electromyographic neuromuscular changes. An integrated approach of animal experiments, computer simulation analyses, and clinical studies may allow us to gain a fundamental understanding of the underlying pathology and interpret the results for clinical translation.

Research paper thumbnail of Age-related degenerative functional, radiographic, and histological changes of the shoulder in nonhuman primates

Journal of Shoulder and Elbow Surgery, 2013

Nonhuman primates have similar shoulder anatomy and physiology compared to humans, and may repres... more Nonhuman primates have similar shoulder anatomy and physiology compared to humans, and may represent a previously underutilized model for shoulder research. This study sought to identify naturally occurring bony and muscular degeneration in the shoulder of nonhuman primates and to assess relationships between structural and functional aspects of the shoulder and measures of physical function of the animals. We hypothesized that age-related degenerative changes in the shoulders of nonhuman primates would resemble those observed in aging humans. Middle-aged (n = 5; ages 9.4-11.8 years) and elderly (n = 6; ages 19.8-26.4 years) female vervet monkeys were studied for changes in mobility and shoulder function, and radiographic and histologic signs of age-related degeneration. Four out of 6 (4/6) elderly animals had degenerative changes of the glenoid compared to 0/5 of the middle-aged animals (P = .005). Elderly animals had glenoid retroversion, decreased joint space, walked slower, and spent less time climbing and hanging than middle-aged vervets (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Physical mobility and shoulder function correlated with glenoid version angle (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Supraspinatus muscles of elderly animals were less dense (P = .001), had decreased fiber cross-sectional area (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001), but similar amounts of nuclear material (P = .085). Degenerative rotator cuff tears were not observed in any of the eleven animals. The vervet monkey naturally undergoes age-related functional, radiographic and histological changes of the shoulder, and may qualify as an animal model for selected translational research of shoulder osteoarthritis.

Research paper thumbnail of Age-related changes affect rat rotator cuff muscle function

Journal of Shoulder and Elbow Surgery, 2014

Background: The influence of age on rotator cuff function and muscle structure remains poorly und... more Background: The influence of age on rotator cuff function and muscle structure remains poorly understood. We hypothesize that normal aging influences rotator cuff function, muscle structure, and regulatory protein expression in an established rat model of aging. Methods: Seventeen rats were obtained from the National Institute on Aging. The supraspinatus muscles in 11 middle-aged (12 months old) and 6 old (28 months old) rats were studied for age-related changes in rotator cuff neuromuscular function by in vivo muscle force testing and electromyography (EMG). Changes in muscle structure and molecular changes were assessed with quantitative immunohistochemistry for myogenic determination factor 1 (MyoD) and myogenic factor 5 (Myf5) expression. Results: Old animals revealed significantly decreased peak tetanic muscle force at 0.5 N and 0.7 N preload tension (P < .05). The age of the animal accounted for 20.9% of variance and significantly influenced muscle force (P ¼ .026). Preload tension significantly influenced muscle force production (P < .001) and accounted for 12.7% of total variance. There was regional heterogeneity in maximal compound motor action potential (CMAP) amplitude in the supraspinatus muscle; the proximal portion had a significantly higher CMAP than the middle and distal portions (P < .05). The expression of muscle regulatory factors MyoD and Myf5 was significantly decreased in old animals compared with middle-aged animals (P < .05). Conclusions: The normal aging process in this rat model significantly influenced contractile strength of the supraspinatus muscle and led to decreased expression of muscle regulatory factors. High preload tensions led to a significant decrease in force production in both middle-aged and old animals.

Research paper thumbnail of Chemical Denervation with Botulinum Neurotoxin A Improves the Surgical Manipulation of the Muscle–Tendon Unit: An Experimental Study in an Animal Model

The Journal of Hand Surgery, 2011

Research paper thumbnail of Recent Advances for the Management of Raynaud Phenomenon Using Botulinum Neurotoxin A

The Journal of Hand Surgery, 2011

Research paper thumbnail of Treatment of Palmar Hyperhidrosis With Botulinum Neurotoxin A

The Journal of Hand Surgery, 2013

Research paper thumbnail of Postural dependence of passive tension in the supraspinatus following rotator cuff repair: A simulation analysis

Clinical Biomechanics, 2011

Background: Despite surgical advances, repair of rotator cuff tears is associated with 20-70% inc... more Background: Despite surgical advances, repair of rotator cuff tears is associated with 20-70% incidence of recurrent tearing. The tension required to repair the torn tendon influences surgical outcomes and may be dependent on the gap length from torn tendon that must be spanned by the repair. Detailed understanding of forces throughout the range of motion (ROM) may allow surgeons to make evidence-based recommendations for post-operative care. Methods: We used a computational shoulder model to assess passive tension and total moment-generating capacity in supraspinatus for repairs of gaps up to 3 cm throughout the shoulder (ROM). Findings: In 60°abduction, increased gap length from 0.5 cm to 3 cm caused increases in passive force from 3 N to 58 N, consistent with those seen during clinical repair. For reduced abduction, passive forces increased substantially. For a 0.5 cm gap, tension throughout the ROM (elevation, plane of elevation, and rotation) is within reasonable limits, but larger gaps are associated with tensions that markedly exceed reported pull-out strength of sutures and anchors. Peak moment for a large 3 cm gap length was 5.09 Nm, a 53% reduction in moment-generating capacity compared to uninjured supraspinatus. Interpretation: We conclude that shoulder posture is an important determinant of passive forces during rotator cuff repair surgery. Choosing postures that reduce forces intraoperatively to permit repair of larger gaps may lead to failure postoperatively when the shoulder is mobilized. For larger defects, loss of strength in supraspinatus may be substantial following repair even if retear is prevented.

Research paper thumbnail of Contributions of Neural Tone to In Vivo Passive Muscle–Tendon Unit Biomechanical Properties in a Rat Rotator Cuff Animal Model

Annals of Biomedical Engineering, 2011

Passive viscoelastic properties of muscle-tendon units are key determinants of intra-and post-ope... more Passive viscoelastic properties of muscle-tendon units are key determinants of intra-and post-operative success. Atrophied, retracted, and stiff muscle-tendon units are technically challenging to manipulate and perform poorly after surgical repair. This study employs botulinum neurotoxin A (BoNT-A)-mediated inhibition of presynaptic acetylcholine release to examine in vivo neural contributions to soft-tissue biomechanical properties. In vivo load-relaxation and active muscle contractile force testing protocols were performed in the rat rotator cuff model. The passive properties were assessed using linear regression analysis and Fung's quasi-linear viscoelastic (QLV) model. BoNT-A injected muscle-tendon units had a significant reduction in force of contraction (p = 0.001). When compared to saline injected controls, the BoNT-A significantly decreased parameter 'A' of the QLV model, which represents the linear elastic response (p = 0.032).

Research paper thumbnail of Evaluation of in vivo rotator cuff muscle function after acute and chronic detachment of the supraspinatus tendon: an experimental study in an animal model

The Journal of Bone and Joint Surgery

Surgical repair of large chronic rotator cuff tears can be technically demanding because it requi... more Surgical repair of large chronic rotator cuff tears can be technically demanding because it requires manipulation of a muscle-tendon unit that is scarred, retracted, and stiffer than normal, all of which contribute to increased tension at the repair site. The purpose of the present study was to characterize the in vivo rotator cuff muscle-tendon unit function after acute and chronic injury at surgically relevant preload tensions. Sixty-two Sprague-Dawley rats were divided into a healthy, uninjured (control) group (n = 22), an acute injury group (n = 20), and a chronic injury group (n = 20) and underwent in vivo muscle force testing and electromyographic testing of the supraspinatus muscle-tendon unit at various preload tensions. Preload tension affected the maximum supraspinatus muscle contractile force in all groups (p < 0.05). At the peak tension required to repair an acute tear, there was a 28% to 30% reduction in maximum tetanic contraction amplitude in all groups (p < 0.0...

Research paper thumbnail of Rotator cuff injuries in professional and recreational athletes

Journal of surgical orthopaedic advances

Professional and recreational athletes involved in contact sports and sports with repetitive over... more Professional and recreational athletes involved in contact sports and sports with repetitive overhead motion are at increased risk for rotator cuff tears. Shoulder anatomy, pathology, and biomechanics place unique stress on the rotator cuff tendons during sports activity. Athletes demand effective treatment to quickly return to elite competition. A PubMed search assessed treatment options providing expedited recovery time and return to competition. Twelve of 231 articles fit the objective criteria; 90.5% of professional contact athletes, 40% of professional overhead athletes, and 83.3% of recreational athletes fully recovered following rotator cuff tear surgical repair. Prompt surgical treatment for full-thickness rotator cuff tears may be appropriate for contact athletes and recreational overhead athletes. Although professional overhead athletes have low recovery rates, surgical repair of full-thickness rotator cuff tears may still be indicated. The authors propose a treatment algo...

Research paper thumbnail of Randomized Comparison of Volar Locking Plates and Intramedullary Nails for Unstable Distal Radius Fractures

The Journal of Hand Surgery, 2015

To compare minimally invasive intramedullary nails (IMN) and volar locking plates (VLP) for the t... more To compare minimally invasive intramedullary nails (IMN) and volar locking plates (VLP) for the treatment of unstable distal radius fractures by evaluating postoperative subjective, radiographic, and functional outcomes. The hypothesis was that IMN patients would have less pain and required less pain medication in the early postoperative period and returned to work earlier than VLP patients. Sixty patients with closed, displaced, unstable, extra-articular, metaphyseal fractures of the distal radius were randomized to receive a VLP or an IMN for internal fixation. Functional outcomes (Quick Disabilities of the Arm, Shoulder, and Hand, Michigan Hand Questionnaire), radiographic measurements (ulnar variance, radial height, inclination, and volar tilt), and range of motion were assessed until final follow-up at 2 years after surgery. Narcotic pain medication use was documented for 5 weeks following surgery. There were 2 groups of 30 patients with IMN (mean age, 55 ± 14 y) or VLP (mean age, 55 ± 16 y) with similar demographics and comorbidities. Patients with IMN regained extension earlier but had similar range of motion to patients with VLP at final follow-up. There was similar improvement in Michigan Hand Questionnaire, Quick Disabilities of the Arm, Shoulder, and Hand, and strength between groups. Five weeks after surgery, fewer IMN patients required narcotic pain medication (13%) than VLP patients (33%). Radiographic outcomes were similar at final follow-up. There were 3 failures with IMN versus 1 failure with VLP. All 10 employed patients with IMN returned to previous work compared with 10 of the 12 employed patients with VLP. Time to return to work was similar for both groups. In a cohort of similar patients, IMN and VLP provided comparable improvement in functional and radiographic outcomes. Patients with IMN required less narcotic pain medication after surgery than VLP patients. Therapeutic II.

Research paper thumbnail of Robotic systems in orthopaedic surgery

The Journal of bone and joint surgery. British volume, 2011

Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate r... more Robots have been used in surgery since the late 1980s. Orthopaedic surgery began to incorporate robotic technology in 1992, with the introduction of ROBODOC, for the planning and performance of total hip replacement. The use of robotic systems has subsequently increased, with promising short-term radiological outcomes when compared with traditional orthopaedic procedures. Robotic systems can be classified into two categories: autonomous and haptic (or surgeon-guided). Passive surgery systems, which represent a third type of technology, have also been adopted recently by orthopaedic surgeons. While autonomous systems have fallen out of favour, tactile systems with technological improvements have become widely used. Specifically, the use of tactile and passive robotic systems in unicompartmental knee replacement (UKR) has addressed some of the historical mechanisms of failure of non-robotic UKR. These systems assist with increasing the accuracy of the alignment of the components and p...

Research paper thumbnail of Achieving accurate ligament balancing using robotic-assisted unicompartmental knee arthroplasty

Advances in orthopedics, 2013

Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients w... more Unicompartmental knee arthroplasty (UKA) allows replacement of a single compartment in patients with limited disease. However, UKA is technically challenging and relies on accurate component positioning and restoration of natural knee kinematics. This study examined the accuracy of dynamic, real-time ligament balancing using a robotic-assisted UKA system. Surgical data obtained from the computer system were prospectively collected from 51 patients (52 knees) undergoing robotic-assisted medial UKA by a single surgeon. Dynamic ligament balancing of the knee was obtained under valgus stress prior to component implantation and then compared to final ligament balance with the components in place. Ligament balancing was accurate up to 0.53 mm compared to the preoperative plan, with 83% of cases within 1 mm at 0°, 30°, 60°, 90°, and 110° of flexion. Ligamentous laxity of 1.31 ± 0.13 mm at 30° of flexion was corrected successfully to 0.78 ± 0.17 mm (P < 0.05). Robotic-assisted UKA allows...

Research paper thumbnail of Tissue-Engineered Approach to Tendon and Ligament Reconstruction: Current Trends

Research paper thumbnail of Arthroscopic Treatment of Bucket-Handle Labral Tear and Acetabular Fracture

Arthroscopy Techniques, 2014

Traumatic hip dislocations are associated with chondral and labral pathology as well as loose bod... more Traumatic hip dislocations are associated with chondral and labral pathology as well as loose bodies that can be incarcerated in the joint. These types of injury often lead to traumatic arthritis. In some cases an osseo-labral fragment may become incarcerated in the joint that is not readily visualized preoperatively. In place of open surgery, hip arthroscopy permits a technique to remove loose bodies and repair labral tears to restore joint congruity and achieve fracture reduction and fixation.

Research paper thumbnail of Injury Mechanisms of Several Common Sports-Related Orthopaedic Injuries

Orthopaedic Biomechanics, 2012

Research paper thumbnail of A Tissue-Engineered Approach to Tendon and Ligament Reconstruction

Research paper thumbnail of Type-1 pericytes accumulate after tissue injury and produce collagen in an organ-dependent manner

Stem Cell Research & Therapy, 2014

Introduction: Fibrosis, or scar formation, is a pathological condition characterized by excessive... more Introduction: Fibrosis, or scar formation, is a pathological condition characterized by excessive production and accumulation of collagen, loss of tissue architecture, and organ failure in response to uncontrolled wound healing. Several cellular populations have been implicated, including bone marrow-derived circulating fibrocytes, endothelial cells, resident fibroblasts, epithelial cells, and recently, perivascular cells called pericytes. We previously demonstrated pericyte functional heterogeneity in skeletal muscle. Whether pericyte subtypes are present in other tissues and whether a specific pericyte subset contributes to organ fibrosis are unknown. Methods: Here, we report the presence of two pericyte subtypes, type-1 (Nestin-GFP-/NG2-DsRed+) and type-2 (Nestin-GFP+/NG2-DsRed+), surrounding blood vessels in lungs, kidneys, heart, spinal cord, and brain. Using Nestin-GFP/NG2-DsRed transgenic mice, we induced pulmonary, renal, cardiac, spinal cord, and cortical injuries to investigate the contributions of pericyte subtypes to fibrous tissue formation in vivo.

Research paper thumbnail of A Human Hair Keratin Hydrogel Scaffold Enhances Median Nerve Regeneration in Nonhuman Primates: An Electrophysiological and Histological Study

Tissue Engineering Part A, 2013

A human hair keratin biomaterial hydrogel scaffold was evaluated as a nerve conduit luminal fille... more A human hair keratin biomaterial hydrogel scaffold was evaluated as a nerve conduit luminal filler following median nerve transection injury in 10 Macaca fascicularis nonhuman primates (NHP). A 1 cm nerve gap was grafted with a NeuraGen Ò collagen conduit filled with either saline or keratin hydrogel and nerve regeneration was evaluated by electrophysiology for a period of 12 months. The keratin hydrogel-grafted nerves showed significant improvement in return of compound motor action potential (CMAP) latency and recovery of baseline nerve conduction velocity (NCV) compared with the saline-treated nerves. Histological evaluation was performed on retrieved median nerves and abductor pollicis brevis (APB) muscles at 12 months. Nerve histomorphometry showed a significantly larger nerve area in the keratin group compared with the saline group and the keratin APB muscles had a significantly higher myofiber density than the saline group. This is the first published study to show that an acellular biomaterial hydrogel conduit filler can be used to enhance peripheral nerve regeneration and motor recovery in an NHP model.

Research paper thumbnail of The science of rotator cuff tears: translating animal models to clinical recommendations using simulation analysis

Knee Surgery, Sports Traumatology, Arthroscopy, 2012

The purpose of this article is to review basic science studies using various animal models for ro... more The purpose of this article is to review basic science studies using various animal models for rotator cuff research and to describe structural, biomechanical, and functional changes to muscle following rotator cuff tears. The use of computational simulations to translate the findings from animal models to human scale is further detailed. A comprehensive review was performed of the basic science literature describing the use of animal models and simulation analysis to examine muscle function following rotator cuff injury and repair in the ageing population. The findings from various studies of rotator cuff pathology emphasize the importance of preventing permanent muscular changes with detrimental results. In vivo muscle function, electromyography, and passive muscle-tendon unit properties were studied before and after supraspinatus tenotomy in a rodent rotator cuff injury model (acute vs chronic). Then, a series of simulation experiments were conducted using a validated computational human musculoskeletal shoulder model to assess both passive and active tension of rotator cuff repairs based on surgical positioning. Outcomes of rotator cuff repair may be improved by earlier surgical intervention, with lower surgical repair tensions and fewer electromyographic neuromuscular changes. An integrated approach of animal experiments, computer simulation analyses, and clinical studies may allow us to gain a fundamental understanding of the underlying pathology and interpret the results for clinical translation.

Research paper thumbnail of Age-related degenerative functional, radiographic, and histological changes of the shoulder in nonhuman primates

Journal of Shoulder and Elbow Surgery, 2013

Nonhuman primates have similar shoulder anatomy and physiology compared to humans, and may repres... more Nonhuman primates have similar shoulder anatomy and physiology compared to humans, and may represent a previously underutilized model for shoulder research. This study sought to identify naturally occurring bony and muscular degeneration in the shoulder of nonhuman primates and to assess relationships between structural and functional aspects of the shoulder and measures of physical function of the animals. We hypothesized that age-related degenerative changes in the shoulders of nonhuman primates would resemble those observed in aging humans. Middle-aged (n = 5; ages 9.4-11.8 years) and elderly (n = 6; ages 19.8-26.4 years) female vervet monkeys were studied for changes in mobility and shoulder function, and radiographic and histologic signs of age-related degeneration. Four out of 6 (4/6) elderly animals had degenerative changes of the glenoid compared to 0/5 of the middle-aged animals (P = .005). Elderly animals had glenoid retroversion, decreased joint space, walked slower, and spent less time climbing and hanging than middle-aged vervets (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Physical mobility and shoulder function correlated with glenoid version angle (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Supraspinatus muscles of elderly animals were less dense (P = .001), had decreased fiber cross-sectional area (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .001), but similar amounts of nuclear material (P = .085). Degenerative rotator cuff tears were not observed in any of the eleven animals. The vervet monkey naturally undergoes age-related functional, radiographic and histological changes of the shoulder, and may qualify as an animal model for selected translational research of shoulder osteoarthritis.

Research paper thumbnail of Age-related changes affect rat rotator cuff muscle function

Journal of Shoulder and Elbow Surgery, 2014

Background: The influence of age on rotator cuff function and muscle structure remains poorly und... more Background: The influence of age on rotator cuff function and muscle structure remains poorly understood. We hypothesize that normal aging influences rotator cuff function, muscle structure, and regulatory protein expression in an established rat model of aging. Methods: Seventeen rats were obtained from the National Institute on Aging. The supraspinatus muscles in 11 middle-aged (12 months old) and 6 old (28 months old) rats were studied for age-related changes in rotator cuff neuromuscular function by in vivo muscle force testing and electromyography (EMG). Changes in muscle structure and molecular changes were assessed with quantitative immunohistochemistry for myogenic determination factor 1 (MyoD) and myogenic factor 5 (Myf5) expression. Results: Old animals revealed significantly decreased peak tetanic muscle force at 0.5 N and 0.7 N preload tension (P < .05). The age of the animal accounted for 20.9% of variance and significantly influenced muscle force (P ¼ .026). Preload tension significantly influenced muscle force production (P < .001) and accounted for 12.7% of total variance. There was regional heterogeneity in maximal compound motor action potential (CMAP) amplitude in the supraspinatus muscle; the proximal portion had a significantly higher CMAP than the middle and distal portions (P < .05). The expression of muscle regulatory factors MyoD and Myf5 was significantly decreased in old animals compared with middle-aged animals (P < .05). Conclusions: The normal aging process in this rat model significantly influenced contractile strength of the supraspinatus muscle and led to decreased expression of muscle regulatory factors. High preload tensions led to a significant decrease in force production in both middle-aged and old animals.

Research paper thumbnail of Chemical Denervation with Botulinum Neurotoxin A Improves the Surgical Manipulation of the Muscle–Tendon Unit: An Experimental Study in an Animal Model

The Journal of Hand Surgery, 2011

Research paper thumbnail of Recent Advances for the Management of Raynaud Phenomenon Using Botulinum Neurotoxin A

The Journal of Hand Surgery, 2011

Research paper thumbnail of Treatment of Palmar Hyperhidrosis With Botulinum Neurotoxin A

The Journal of Hand Surgery, 2013

Research paper thumbnail of Postural dependence of passive tension in the supraspinatus following rotator cuff repair: A simulation analysis

Clinical Biomechanics, 2011

Background: Despite surgical advances, repair of rotator cuff tears is associated with 20-70% inc... more Background: Despite surgical advances, repair of rotator cuff tears is associated with 20-70% incidence of recurrent tearing. The tension required to repair the torn tendon influences surgical outcomes and may be dependent on the gap length from torn tendon that must be spanned by the repair. Detailed understanding of forces throughout the range of motion (ROM) may allow surgeons to make evidence-based recommendations for post-operative care. Methods: We used a computational shoulder model to assess passive tension and total moment-generating capacity in supraspinatus for repairs of gaps up to 3 cm throughout the shoulder (ROM). Findings: In 60°abduction, increased gap length from 0.5 cm to 3 cm caused increases in passive force from 3 N to 58 N, consistent with those seen during clinical repair. For reduced abduction, passive forces increased substantially. For a 0.5 cm gap, tension throughout the ROM (elevation, plane of elevation, and rotation) is within reasonable limits, but larger gaps are associated with tensions that markedly exceed reported pull-out strength of sutures and anchors. Peak moment for a large 3 cm gap length was 5.09 Nm, a 53% reduction in moment-generating capacity compared to uninjured supraspinatus. Interpretation: We conclude that shoulder posture is an important determinant of passive forces during rotator cuff repair surgery. Choosing postures that reduce forces intraoperatively to permit repair of larger gaps may lead to failure postoperatively when the shoulder is mobilized. For larger defects, loss of strength in supraspinatus may be substantial following repair even if retear is prevented.

Research paper thumbnail of Contributions of Neural Tone to In Vivo Passive Muscle–Tendon Unit Biomechanical Properties in a Rat Rotator Cuff Animal Model

Annals of Biomedical Engineering, 2011

Passive viscoelastic properties of muscle-tendon units are key determinants of intra-and post-ope... more Passive viscoelastic properties of muscle-tendon units are key determinants of intra-and post-operative success. Atrophied, retracted, and stiff muscle-tendon units are technically challenging to manipulate and perform poorly after surgical repair. This study employs botulinum neurotoxin A (BoNT-A)-mediated inhibition of presynaptic acetylcholine release to examine in vivo neural contributions to soft-tissue biomechanical properties. In vivo load-relaxation and active muscle contractile force testing protocols were performed in the rat rotator cuff model. The passive properties were assessed using linear regression analysis and Fung's quasi-linear viscoelastic (QLV) model. BoNT-A injected muscle-tendon units had a significant reduction in force of contraction (p = 0.001). When compared to saline injected controls, the BoNT-A significantly decreased parameter 'A' of the QLV model, which represents the linear elastic response (p = 0.032).