Glenn S Fleisig

American Sports Medicine Institute

Background: While numerous studies exist evaluating the short-term clinical outcomes for patients who have undergone elbow arthroscopy for osteochondritis dissecans (OCD) of the capitellum, the literature on minimum 2-year clinical outcomes for a large cohort of patients is limited. Purpose: /Hypothesis: We hypothesized that clinical outcomes fo...

Background: Baseball pitchers employ various contralateral trunk tilt (CTT) positions when pitching depending on if they have an overhand, three-quarter, or sidearm delivery. There are no known studies that have examined how pitching biomechanics are significantly different in professional pitchers with varying amounts of CTT, which may provide in...

Background An analysis of the demographics and training of head team physicians (HTPs) in professional sports would be valuable for evaluating training programs and as a resource for aspirant HTPs. Purpose To outline common characteristics among professional sport HTPs. Study Design Cross-sectional study. Methods In June 2021, publicly available...

Background Shoulder pain due to labral tears and biceps tendonitis is commonly found in softball players. Surgical options include labral repair and biceps tenodesis. While past studies are limited by heterogeneous study groups from multiple sports, this is the first study that assesses clinical outcomes and return to play rates for fast-pitch soft...

Background Biomechanical efficiency, defined as fastball velocity per unit of normalized elbow varus torque, is a relatively new metric applied to improving the performance and health of baseball pitching. Purpose/Hypothesis The purpose of this work was to evaluate kinematic parameters influencing biomechanical efficiency among professional and co...

Background Ulnar collateral ligament (UCL) surgery continues to demonstrate excellent clinical outcomes and a high return-to-play (RTP) rate with a low complication rate. Recent studies have demonstrated similar clinical outcomes for baseball players who have undergone either UCL reconstruction or UCL repair. In comparison, few studies have assesse...

Endoscopic gluteus medius repair is indicated after failed conservative management for debilitating peritrochanteric hip pain. In our experience, most of these surgeries are performed on women, 45 to 75 years old. Often for undersurface high-grade partial-thickness tears and some small full-thickness tears, a single-row repair technique is performe...

Background Normative data for passive range of motion are well-established, but daily living is comprised of active motion. The purpose of this study was to establish normative values for active range of motion of the shoulder across age, sex, and arm. Hypothesis Our hypotheses were that active range of motion of the shoulder (1) decreases with ag...

Objective: To evaluate the outcomes of patients treated with a novel minimally-invasive complete release of the first dorsal compartment percutaneously under ultrasound guidance using an 18-gauge needle with an 18 blade at the tip. Design: Retrospective case series. Nine adults (ten wrists) were included in the study of this technique. All patie...

Background: Lateral epicondylitis is one of the most common causes of elbow pain. Most patients recover with conservative treatments; however, some patients require surgical intervention. There are 3 common procedures offered: open tenotomy, arthroscopic tenotomy, and percutaneous microtenotomy. In comparison, percutaneous microtenotomy has been p...

Objectives In the medical literature regarding injuries of the ulnar collateral ligament (UCL), baseball players comprise a majority of the athletes studied. Baseball players endure repetitive valgus forces in the elbow that can cause damage to the UCL with the overhead throwing motion. However, there are limited studies in the literature regarding...

The objective was to assess how patellofemoral loads (joint force and stress) change while lunging with step length and step height variations. Sixteen participants performed a forward lunge using short and long steps at ground level and up to a 10-cm platform. Electromyography, ground reaction force, and 3D motion were captured, and patellofemoral...

Background: A plantar fasciotomy using a microdebrider coblation wand may be an effective treatment for treating chronic plantar fasciitis. The objective of this prospective study was to determine the success rate of performing a plantar fasciotomy using a microdebrider coblation wand to treat plantar fasciitis and determine utility of ultrasonogr...

BACKGROUND Previous studies have reported return to play (RTP) rates for athletes after lumbar discectomy, but not specifically younger athletes. The purpose of this study was to evaluate RTP rate of young athletes after lumbar microdiscectomy. METHODS Medical records for a single spine surgeon were reviewed to identify lumbar microdiscectomy pati...

The purpose of this study was to investigate potential differences in lead knee extension velocity, elbow varus torque and lead knee extension (the change in lead knee flexion from foot contact to ball release) in high and low velocity professional pitchers. Three-dimensional motion capture (480 Hz) was used to assess 322 professional pitchers. T-t...

Background: Forward and side lunge exercises strengthen hip and thigh musculature, enhance patellofemoral joint stability, and are commonly used during patellofemoral rehabilitation and training for sport. Hypothesis/purpose: The purpose was to quantify, via calculated estimates, patellofemoral force and stress between two lunge type variations...

Background Recent innovative techniques have led to renewed interest in ulnar collateral ligament (UCL) repair. Although early outcome data regarding the clinical outcome of overhead athletes undergoing UCL repair with augmentation have been encouraging, long-term data are still needed to evaluate both the appropriate indications and success rate f...

Objectives All-suture anchor use for rotator cuff repair is increasing. Potential benefits of these anchors include less bone loss from anchor hole drilling and decreased injury to the chondral surface with anchor pullout. Minimal evidence exists comparing clinical outcomes of all suture to solid medial row anchor fixation in double row suture brid...

Background: Trends over time in the incidence of ulnar collateral ligament (UCL) surgeries in National Collegiate Athletic Association Division I baseball players are currently unknown. Purpose/hypothesis: The purpose of this study was to evaluate the trends in UCL surgeries over 3 years in Division I baseball programs. We hypothesized that surg...

Introduction: Open surgical trigger finger release has limited success with complications; however, percutaneous techniques have a successful alternative. There is limited understanding of the success of percutaneous trigger finger release. Objective: To prospectively evaluate the functional outcomes of patients with Green classification Grade 2...

Baseball coaches often focus on the landing position of a pitcher’s front foot as a key aspect of mechanics. Furthermore, controversy persists regarding positioning the rear foot on the first base or third base end of the rubber. The purpose of this study was to determine the effect of rear and front foot placement on pitching biomechanics. Our hyp...

Background There is limited literature regarding outcomes after operative treatment of displaced medial epicondyle avulsion fractures in adolescent athletes. Most studies have had a relatively small sample size and have not assessed return to play of the overhead athlete. Purpose To examine return to play and outcomes of youth overhead athletes wh...

Background: There is a lack of evidence regarding the success of ulnar collateral ligament (UCL) revision reconstruction. Understanding outcomes after UCL revision reconstruction is important in clinical decision making for overhead athletes. Purpose: To evaluate return to play and patient-reported outcomes after UCL revision reconstruction. Stud...

Background: Bone marrow aspiration (BMA) is among a group of autologous cell-based therapies currently being explored to treat osteoarthritis (OA). Materials & methods: This retrospective case study observed ten patients (13 knees) with severe knee OA who failed extensive conservative treatment and were treated with BMA injection using a novel, pur...

Background: Baseball pitching injuries are increasing at an alarming rate. While weighted ball throwing programs may be effective at increasing pitching velocity, previous research has identified a 24% injury rate and a 3.3° increase in shoulder external rotation (ER) range of motion (ROM) after performing a 6-week program. However, previous resea...

Objective: Trigger finger at the A1 pulley is a common cause of hand pain leading to functional limitations. This study evaluated the outcomes of patients treated with a micro-invasive ultrasound-guided trigger finger release technique using an 18 blade and described three tests that confirm a complete release. Design: A retrospective chart revi...

Objectives Understanding the differences in baseball pitching biomechanics between American and Japanese pitchers may help with training and developing these athletes. The purpose of this study was to investigate the kinematic and kinetic differences in collegiate baseball pitchers from United States of American and Japan. Design Controlled labora...

Objective To compare screw fixation strength for subtalar arthrodesis. Methods Eight matched pairs of cadaver feet underwent subtalar joint arthrodesis with two 7.3mm cannulated screws. Randomization was used to assign screw orientation, such that one foot in each pair was assigned dorsal to plantar screw orientation (DP Group), and the other foot...

Objectives: To determine whether increasing pitching distance for adult baseball pitchers would affect their upper extremity kinetics, full-body kinematics, and pitched ball kinematics (ball velocity, duration of ball flight, vertical and horizontal break, strike percentage). Design: Controlled laboratory study. Methods: Twenty-six collegiate...

Background Plantar fasciitis is the most common cause of heel pain in adults. Multiple conservative treatment plans exist; however, some cases do not obtain significant clinical improvement with conservative treatment and require further intervention. This retrospective case study evaluated the success rate of percutaneous plantar fasciotomy and co...

Participation in sports has been an important part of culture and childhood development. Injuries to the lumbar spine can preclude participation with devastating social, psychological, and physical consequences. The clinical presentation of adolescent lumbar disc herniations often differs from adult patients (less neurologic symptoms), frequently d...

Category Basic Sciences/Biologics, Hindfoot Introduction/Purpose Arthrodesis of the subtalar joint is performed for various arthritic and instability problems to correct alignment and relieve pain. For talocalcaneal pathologies, isolated subtalar arthrodesis has been advocated with the advantages of lower risk of adjacent joint arthritis and nonun...

Background The variability of throwing metrics, particularly elbow torque and ball velocity, during structured long-toss programs is unknown. Hypothesis (1) Elbow torque and ball velocity would increase as throwers progressed through a structured long-toss program. (2) Intrathrower reliability would be high while interthrower reliability would be...

Background Injury prevalence has been well described among baseball athletes; similarly, a better understanding of injuries in softball athletes is needed. Purpose To examine shoulder and elbow injury epidemiology among high school softball athletes in the United States. Study Design Descriptive epidemiological study. Methods Injury data were ob...

The purpose of this study was to explore the relationship between variability in pitching kinematics and consistency in pitch location. Data were collected for 47 healthy baseball pitchers throwing ten full-effort fastballs to the centre of the strike zone. For each pitch, 20 kinematic parameters were calculated with an automated motion capture sys...

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/Hypo...

Background The probability of returning to competition for injured baseball pitchers is similar after ulnar collateral ligament (UCL) repair as after UCL reconstruction, but the time to return is significantly quicker after UCL repair. Previous research has found no differences in pitching biomechanics between pitchers with and without a history of...

Major League Baseball (MLB) players represent a unique population of individuals in the United States: a select group of men who possess the athleticism, strength, and acumen to navigate into organized professional baseball at the highest level and who are compensated quite well. What do we know about their health and mortality risks? In this issue...

Objectives: To determine whether mound height is associated with baseball movement (velocity, spin and break) and baseball pitching biomechanics (kinematics and kinetics). Design: Controlled laboratory study. Methods: Twenty collegiate baseball pitchers threw five fastballs and five curveballs from four different mound heights (15cm, 20cm, 25c...

The anterior bundle of the ulnar collateral ligament (UCL) is the primary restraint to valgus force at the elbow, especially during the arm-cocking and arm-acceleration phases of the overheard throwing cycle. Injuries of the UCL can range from partial thickness tears, end avulsions, to chronic attritional ruptures with poor tissue quality. The inci...

Objectives Recent studies in the literature have highlighted the progressive increase in the incidence of ulnar collateral ligament (UCL) injuries to the elbow in baseball players of all levels. However, knowledge of the incidence and other epidemiological factors regarding UCL injuries, specifically in college baseball players, is currently lackin...

Objectives Return to play (RTP) are high following lower extremity injuries; however, objective sport specific clearance criteria are lacking. In ACL rehabilitation for example, current tests that are used such as single leg hop, isokinetic testing, and quad strength are not sport specific and do not take fatigue into account. With the development...

Objectives The variability of throwing metrics, particularly elbow torque and ball velocity, during structured long-toss programs is yet to be fully elucidated. The primary aims of this study were to assess various throwing metrics through a structured long-toss program using wearable technology and to quantify the intra and inter thrower variabili...

Objectives Progressive throwing programs are a mainstay of rehabilitating the throwing athlete after injury or surgery. Athletes are commonly asked to throw at reduced levels of effort (i.e. “50% effort”, ”75%,” etc) to minimize stress to healing tissues. However, it is unknown whether players’ perceived exertion matches actual exertion. The purpos...

Background: During rehabilitation throwing programs, baseball players are commonly asked to throw at reduced levels of effort (ie, 50% effort, 75% effort, etc) to moderate stress to healing tissues. It is currently unknown how changes in players' perceived exertion compares with changes in actual exertion during structured long-toss programs. Pur...

Background:: There has been a renewed interest in ulnar collateral ligament (UCL) repair in overhead athletes because of a greater understanding of UCL injuries, an improvement in fixation technology, and the extensive rehabilitation time to return to play. Purpose/hypothesis:: To evaluate the clinical outcomes of a novel technique of UCL repair...

Context: High loads in the elbow during baseball pitching can lead to serious injuries, including injuries to the ulnar collateral ligament. These injuries have substantial implications for individual pitchers and their teams, especially at the professional level of competition. With a trend toward increased ball velocity in professional baseball,...

Background: Although baseball injuries are common in both Japan and the United States, the majority of pitching injuries in Japanese players occur at the shoulder, whereas most pitching injuries in American players occur at the elbow. A biomechanical comparison between Japanese and American pitchers may help to identify the different injury mechan...

Background: Pitching injuries continue to be a serious problem, with adolescents now representing the group with the most injuries. Some have proposed that lowering or eliminating the pitching mound in youth baseball may reduce joint stress and subsequent injuries. Another potential risk factor is advancing from youth to adult pitching distance wi...

Objectives There has been a renewed interest in UCL repair in overhead athletes. This is largely due to greater understanding of UCL pathology, improvement in fixation technology and the extensive rehab required to return from UCL reconstruction. Initial data regarding UCL repair in overhead athletes was poor and therefore UCL repair was largely ab...

Background: Emphasis on enhancing baseball pitch velocity has become popular, especially through weighted-ball throwing. However, little is known about the physical effects or safety of these programs. The purpose of this study was to examine the effects of training with weighted baseballs on pitch velocity, passive range of motion (PROM), muscle...

The purpose of this study was to assess biomechanical differences among overhand, three-quarter, and sidearm arm-slot professional baseball pitchers. It was hypothesized that kinematic-and-kinetic differences would be found among the three groups, with sidearm pitchers demonstrating greater movement along the transverse plane, and overhead pitchers...

Background Recent reports have highlighted the progressive increase in the incidence of ulnar collateral ligament (UCL) injuries to the elbow in baseball players of all levels. However, knowledge of the incidence and other epidemiological factors regarding UCL injuries, specifically in college baseball players, is currently lacking. Purpose To eva...

While 10% of the general population is left-handed, 27% of professional baseball pitchers are left-handed. Biomechanical differences between left- and right-handed college pitchers have been previously reported, but these differences have yet to be examined at the professional level. Therefore, the purpose of this study was to compare pitching biom...

Research has shown relations between amount of baseball pitching and overuse injuries, as well as between poor mechanics and high loads on the elbow and shoulder. However, overuse injuries continue to be a problem from youth to professional sports. Emerging wearable technology may enable players, parents, coaches, leagues, and clinicians to monitor...

Background: Few studies have documented the outcomes of superior labral anterior-posterior (SLAP) repairs in baseball players. Furthermore, the results of these previous studies varied widely and were based on small numbers of patients. Hypothesis/Purpose: The purpose was to report return-to-play (RTP) rates and validated subjective outcome scores...

Background: In professional baseball pitchers, pitching biomechanics have not been examined for the slider, and the only known study for the curveball and changeup examined limited kinetics. Moreover, no known studies have investigated pitching biomechanics between strikes and balls. Purpose/Hypothesis: The purpose was to compare pitching biomecha...

Background: Pitching biomechanics are associated with performance and risk of injury in baseball. Previous studies have identified biomechanical differences between youth and adult pitchers but have not investigated changes within individual young pitchers as they mature. Hypothesis: Pitching kinematics and kinetics will change significantly dur...

Background: Likely due to the high level of strain exerted across the elbow during the throwing motion, elbow injuries are on the rise in baseball. To identify at-risk athletes and guide postinjury return-to-throw programs, a better understanding of the variables that influence elbow varus torque is desired. Purpose: To describe the within-subje...

Forces imparted by the fingers onto a baseball are the final, critical aspects for pitching, however these forces have not been quantified previously as no biomechanical technology was available. In this study, an instrumented baseball was developed for direct measurement of ball reaction force by individual fingers and used to provide fundamental...

The purpose of this study was to determine how often flaws in pitching mechanics identified from biomechanical analysis are corrected. The biomechanics of 46 baseball pitchers were evaluated twice, with an average of 12 months (range 2–48 months) between evaluations. Pitchers were healthy at the time of both evaluations, competing at the high schoo...

Objectives Likely due to the high level of strain exerted across the elbow during the throwing motion, elbow injuries are on the rise in baseball. In order to identify at risk athletes and guide post-injury return to throw programs, a better understanding of the variables that influence elbow varus torque is desired. The purpose of this work was to...

The purpose of this study was to investigate the kinematic and kinetic differences between American and Japanese baseball pitchers. Kinematic and kinetic data were analyzed for 11 American pitchers (21±2 y, 190±6 cm, 93±9 kg) and 11 Japanese pitchers (21±1 y, 180±6 cm, 81±7 kg) using 3D motion capture (480 Hz). The American pitchers generated faste...

Background: Anterior cruciate ligament (ACL) injuries occur commonly in football. Recent work has reported ACL reconstruction (ACLR) as one of several orthopaedic procedures with unfavorable outcomes for professional athletes. The performance impact to defensive players after surgery has not been quantified. Purpose: To quantify the effect of AC...

This article aims to evaluate factors associated with chondral and meniscal lesions in primary and revision anterior cruciate ligament (ACL) reconstructions. ACL reconstructions from 2001 to 2008 at a single institution were retrospectively analyzed. Logistic regression was used to estimate the association between chondral and meniscal injuries and...

Background: Weighted-ball throwing programs are commonly used in training baseball pitchers to increase ball velocity. The purpose of this study was to compare kinematics and kinetics among weighted-ball exercises with values from standard pitching (ie, pitching standard 5-oz baseballs from a mound). Hypothesis: Ball and arm velocities would be...

Ulnar collateral ligament (UCL) injury is a common condition often described in overhead athletes. The function of the UCL is to stabilize the medial elbow, but overuse can compromise the integrity of the ligament often requiring surgical reconstruction. With a better understanding of the patient population most affected by surgical UCL injuries, p...