Orthopaedics 2019 Projects

Project Title: Clinical and Basic Research of Malignant Peripheral Nerve Sheath Tumors

Faculty Mentor’s Name: Margaret Wallace and Mark Scarborough
Email: peggyw@ufl.edu

Student’s Name: Daniel Knewitz
Email: danielknewitz@ufl.edu

Project Description:

Despite currently afflicting 1/1900 – 1/3500 people worldwide, neurofibromatosis type 1 (NF1) is a progressive autosomal dominant disease that needs much greater understanding through research to realize the goal of an effective therapy or potential cure (Stewart et al., 2018). Although this disorder is one-hundred percent penetrant by late adulthood, with most patients diagnosed in childhood, the prognosis of patients who subsequently develop malignant peripheral nerve sheath tumors (MPNST) is especially poor. MPNSTs are rare sarcomas that typically arise from pre-existing plexiform neurofibromas in patients with NF1. Plexiform neurofibromas, benign Schwann cell tumors that can arise anywhere on the peripheral nerves, develop in about fifty percent of individuals with NF1. This type of neurofibroma has a 10-30% chance of developing into an MPNST (Stewart et al., 2018), and patients with MPNSTs have a less than 50% 5-year survival rate (Stasik et al., 2006; Hwang et al., 2017). Individuals who do not have NF1 can develop a sporadic MPNST, and these represent about half of all MPNST cases, with a general population incidence of 1/100,000 (orphanet.com).

Because of its overall rarity, there have been no clinical trials specifically for MPNSTs, and thus information about natural history and response to therapies in the literature is sparse. Typically, MPNSTs are managed with protocols for soft-tissue sarcomas (Bradford and Kim, 2015). Surgery is the front-line therapy offered, with a goal of resecting the tumor with wide margins. Chemotherapy and/or radiation regimens are also used, to reduce the chances of local recurrence or to prevent/target metastases, but the utility and choice of these therapies has not been fully defined in MPNSTs (Bradford and Kim, 2015). Thus, data from experience of institutions managing relatively large sets of patients with MPNSTs is important to inform the rest of the medical community (Carroll, 2016).

There are a limited number of publications reporting MPNST clinical outcomes comparing subjects with and without NF1, with the most complete reports summarized in Table 1. Most studies found a reduced survival in patients with NF1 compared to those without (sporadic, non-NF MPNST), but there was more inconsistency in the prognostic factors identified. Some of the publications only had minimal information about radiotherapy and/or the type(s) of chemotherapy, which limits the utility of the data.

Project Title: Concussions Symptoms Predictive of Subsequent Musculoskeletal Injury

Faculty Mentor’s Name: Daniel Herman
Email: hermadc@ortho.ufl.edu

Student’s Name: Whit Wiggins
Email: whitman5723@ufl.edu

Project Description:

Concussions are a common sports injury which have received a large amount of media attention due to its potential for short and long-term consequences in athletes of all ages. Concussions result in different combinations of a multitude of symptoms ranging from headaches, to emotional lability, to feeling slow “in a fog.” Clearly, one or any combination of these symptoms would be detrimental to an athlete’s quality of life; however, research has demonstrated that these symptoms are not the only negative outcome. Prior research has also demonstrated an increased risk of musculoskeletal injury when previously concussed athletes return to competition. A study of collegiate athletes found that the odds of sustaining a musculoskeletal injury in previously concussed athletes was 3.39 times compared to matched non-concussed athletes (Herman et al. 2017).

The reason for this increased risk of musculoskeletal injury following a concussion may be related to decrements in neurocognition and motor system function. Research has shown that declines in neuromuscular balance and attention, such as after a concussion, are associated with higher risk of musculoskeletal injury (Guy et al. 2016 and Read et al. 2016). Study has also shown that concussed athletes who sustained musculoskeletal injuries after returning to competition displayed a worsened dual-task gait than participants who did not suffer an injury (Howell et al. 2018).

The increased risk of musculoskeletal injury must be considered by clinicians when making recommendations for when athletes can safely return to competition following a concussion; yet, there have been no prior studies investigating what factors may increase or decrease the risk of subsequent musculoskeletal injury. However, prior research has shown that certain presenting symptoms of a concussion are able to predict the length of time it will take to recover (Lau et al. 2011). These studies have classified concussions symptoms in different thematic categories: Migraine, Cognitive, Sleep, and Neuropsychiatric symptoms. The varying presentations of concussions suggests that the predominant symptoms for a given concussion may correlate to different cortical injuries and hence different levels of subsequent risk for musculoskeletal injury.

The purpose of this study is to determine the symptoms and symptom clusters at the time of initial concussion presentation that are most predictive of subsequent musculoskeletal injury. Knowing which factors increase an athlete’s risk for musculoskeletal injury will allow clinicians to make better recommendations for a safe return to competition. The specific aim of this study is to determine the symptoms and symptom clusters at the time of initial concussion presentation and assessment that are predictive of subsequent musculoskeletal injury risk after in-season return to play.

Project Title: Face Shear Failure of Anatomic Glenoid Components: A unique failure mechanism

Faculty Mentor’s Name: Joseph King
Email: kinkjj@ortho.ufl.edu

Student’s Name: William Powers
Email: wpowers32@ufl.edu

Project Description:

Anatomic total shoulder arthroplasty (TSA) is a reliable operation to provide pain relief and improve function for end-stage primary osteoarthritis of the glenohumeral joint.1,6 However, there remains a high incidence of radiographic lucencies about the glenoid component at midterm follow up, with reports showing up to 60% of TSAs affected.2,4,5 In more than one third of cases, components have been shown to be radiographically loose.2,5 Despite high rates of radiographic loosening, revision rates remain significantly lower, averaging approximately 1% per year.4,6,7 The majority of failures occur secondary to micromotion at the bone cement interface, which can be secondary to rotator cuff failure. Franklin, et al. described this failure mechanism as the rocking horse glenoid.3

Newer designs have introduced monoblock polyethylene glenoids with backside ingrowth pegs.2,6,7,17,26 These designs use hybrid fixation, with cementation of the peripheral pegs and bone ingrowth centrally. Park et al reported on 69 hybrid fixation all polyehlene central ingrowth glenoids (Affiniti Cortiloc,Tornier, Edina , MN) at a mean follow up 28 months.19 In this group post operative Lazarus scores exceeded grade 2 in 18% of shoulders. This may be secondary to failure of bone to ingrow into the central peg, which is associated with higher radiolucent line scores.15,26 The long term advantages of metal peg ingrowth components remains unproven.

Project Title: Running Mechanics and Metabolic Responses in Obese and Health-Weight Runners

Faculty Mentor’s Name: Dr. Heather Vincent
Phone: 352-273-7459
Email: vincehk@ortho.ufl.edu

Student’s Name: Jack Kilgore
Email: jkilgore15@ufl.edu

Project Description:

The popularity of running is growing in the United States, and the demographics of this active group are shifting. Runners of diverse body sizes and ages are participating in running, with over 35% of new runners falling into the overweight or obese classifications. Approximately 16% of runners may start running specifically because of weight concerns. The popular media are currently focused on debates of whether overweight people can and should run. An assumption has been that overweight persons who run are at inherent risk for musculoskeletal injury to the modified body geometry and elevated mechanical stress on the load-bearing joints of the body. What is known is that obesity may place a considerable physical burden on the musculoskeletal system with particular emphasis on weight bearing joints (low back, hips, knees, and ankles). Obesity is a strong contributor to systemic inflammation and joint pain and degeneration, and subsequent comorbid joint disease. Carrying excessing weight during sustained high intensity exercise requires substantially more muscle effort than carrying healthy weight. In contrast, running has numerous known health benefits including cardiovascular fitness, favorable metabolic adaption, fat oxidation, blood pressure reduction, improvement of endocrine profiles, and mental outlook.

It is not known whether overweight people adjust motion to control joint excursion and metabolic cost to maintain physical comfort. Despite the known benefits of running, there is a scientific gap regarding the simultaneous effects of running on joint kinematics, kinetics, cardiopulmonary, and metabolic responses in overweight runners. The available research has been limited to examination of the energy cost of exercise and joint motion in obese persons with treadmill walking or walking and jogging. Other investigations have examined energetics and mechanics in obese children.

Project Title: The Effect of Neurocognition on Musculoskeletal Injury Rehabilitation

Faculty Mentor’s Name: Dr. Daniel Herman
Email: hermadc@ortho.ufl.edu

Student’s Name: Troy Hamner
Email: thamner004@ufl.edu

Project Description:

Movement tasks are known to require the integration of a multitude of sensory inputs both intrinsically and from the environment to coordinate movement. In an athletic environment, an athlete must modulate attention, sensory inputs, and motor planning efficiently to optimize performance (1). With anterior cruciate ligament (ACL) rupture there is loss of afferent input from mechanoreceptors with additional inflammatory sequelae disrupting afferent signals from the injured ligament (2). It is thought that this disruption of signaling would require a compensatory response by other sensory inputs to mitigate the deafferentation caused by the ligament rupture.

Kapreli et al investigated the compensatory response of the central nervous system (CNS) in individuals following ACL injury. Using neurological imaging techniques, it was found that individuals who had ACL reconstruction (ACLR) had increased activation of brain regions associated with visual processing (3). This response can be explained via compensation where the increased visuospatial processing of ACL injured individuals takes the place of the lost afferent information that would typically come from mechanoreceptors in a healthy ACL. Additionally, investigation of brain activation changes in ACLR individuals by Grooms et al showed increased activation of the secondary somatosensory brain area, which is suggestive of a reorganization of cortical sensory processing in response to the ACL and associated knee trauma (4). Furthermore, Swanik et al compared neurocognitive performance of ACL injured athletes with matched controls and found that those with ACL injury demonstrated slower visual processing speeds (5). These investigations implicate the crucial role of activation of secondary sensory inputs in motor learning and performance for individuals with ACL injury to compensate for lost afferent sensation from the injured knee.

These findings implicate the heightened importance of visuospatial processing for ACLR athletes in order to compensate for the loss of afferent sensory input from the knee after disruption of the native ACL. In light of the evidence indicating these patients rely on visual sensory input after ACLR, it stands to reason that those patients with greater levels of inherent visual processing ability would have a greater chance for a strong rehabilitation outcome compared to those patients who have lesser levels of visual processing ability. Pilot data of the applicant’s mentor appears to support this relationship, which demonstrates that among 17 high school athletes who experienced ACL injury and subsequent reconstruction, those athlete with greater levels of pre-injury visual processing had shorter durations of post-surgical rehabilitation. Linear regression analyses indicated that for every additional point scored on the visual processing section of the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), an athlete required one less week of rehabilitation time before returning to play.

However, the effect of baseline neurocognitive performance has not been investigated on a large-scale basis, nor has the effect of other domain of neurocognitive functioning been explored. Therefore, the goal of this research proposal is to investigate the role of neurocognitive factors on rehabilitation time requirements for athletes with ACL injury.

Project Title: Upper Extremity, Trunk and Lower Extremity Physical Measures in Overhead Athletes: Longitudinal Changes and Relationship to Workload, Experience, and Injury

Faculty Mentor’s Name: Dr. Kevin Farmer
Email: farmekw@ortho.ufl.edu

Student’s Name: Cameron Guy
Email: crguy995@ufl.edu

Project Description:

Concussions are a common sports injury which have received a large amount of media attention due to its potential for short and long-term consequences in athletes of all ages. Concussions result in different combinations of a multitude of symptoms ranging from headaches, to emotional lability, to feeling slow “in a fog.” Clearly, one or any combination of these symptoms would be detrimental to an athlete’s quality of life; however, research has demonstrated that these symptoms are not the only negative outcome. Prior research has also demonstrated an increased risk of musculoskeletal injury when previously concussed athletes return to competition. A study of collegiate athletes found that the odds of sustaining a musculoskeletal injury in previously concussed athletes was 3.39 times compared to matched non-concussed athletes (Herman et al. 2017).

The reason for this increased risk of musculoskeletal injury following a concussion may be related to decrements in neurocognition and motor system function. Research has shown that declines in neuromuscular balance and attention, such as after a concussion, are associated with higher risk of musculoskeletal injury (Guy et al. 2016 and Read et al. 2016). Study has also shown that concussed athletes who sustained musculoskeletal injuries after returning to competition displayed a worsened dual-task gait than participants who did not suffer an injury (Howell et al. 2018).

The increased risk of musculoskeletal injury must be considered by clinicians when making recommendations for when athletes can safely return to competition following a concussion; yet, there have been no prior studies investigating what factors may increase or decrease the risk of subsequent musculoskeletal injury. However, prior research has shown that certain presenting symptoms of a concussion are able to predict the length of time it will take to recover (Lau et al. 2011). These studies have classified concussions symptoms in different thematic categories: Migraine, Cognitive, Sleep, and Neuropsychiatric symptoms. The varying presentations of concussions suggests that the predominant symptoms for a given concussion may correlate to different cortical injuries and hence different levels of subsequent risk for musculoskeletal injury.

The purpose of this study is to determine the symptoms and symptom clusters at the time of initial concussion presentation that are most predictive of subsequent musculoskeletal injury. Knowing which factors increase an athlete’s risk for musculoskeletal injury will allow clinicians to make better recommendations for a safe return to competition.

Disclaimer: The images on this page were taken prior to the national guidelines of face coverings and social distancing.