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There is a growing body of evidence documenting loads applied to the anterior cruciate ligament (ACL) for weight-bearing and non-weight-bearing exercises. ACL loading has been quantified by inverse dynamics techniques that measure anterior shear force at the tibiofemoral joint (net force primarily restrained by the ACL), ACL strain (defined as change in ACL length with respect to original length and expressed as a percentage) measured directly in vivo, and ACL tensile force estimated through mathematical modeling and computer optimization techniques. A review of the biomechanical literature indicates the following: ACL loading is generally greater with non-weight-bearing compared to weight-bearing exercises; with both types of exercises, the ACL is loaded to a greater extent between 10° to 50° of knee flexion (generally peaking between 10° and 30°) compared to 50° to 100° of knee flexion; and loads on the ACL change according to exercise technique (such as trunk position). Squatting with excessive forward movement of the knees beyond the toes and with the heels off the ground tends to increase ACL loading. Squatting and lunging with a forward trunk tilt tend to decrease ACL loading, likely due to increased hamstrings activity. During seated knee extension, ACL force decreases when the resistance pad is positioned more proximal on the anterior aspect of the lower leg, away from the ankle. The evidence reviewed as part of this manuscript provides objective data by which to rank exercises based on loading applied to the ACL. The biggest challenge in exercise selection post-ACL reconstruction is the limited knowledge of the optimal amount of stress that should be applied to the ACL graft as it goes through its initial incorporation and eventual maturation process. Clinicians may utilize this review as a guide to exercise selection and rehabilitation progression for patients post-ACL reconstruction.

Controlled laboratory study.To test for kinematic and kinetic differences between baseball pitching from a mound and long-toss on flat ground.Long-toss throws from flat ground are commonly used by baseball pitchers for rehabilitation, conditioning, and training. However, there is controversy over the biomechanics and functionality of such throws.Seventeen healthy, college baseball pitchers pitched fastballs 18.4 m from a mound to a strike zone, and threw 37 m, 55 m, and maximum distance from flat ground. For the 37-m and 55-m throws, participants were instructed to throw "hard, on a horizontal line." For the maximum-distance throw, no constraint on trajectory was given. Kinematics and kinetics were measured with a 3-dimensional, automated motion analysis system. Repeated-measures analyses of variance, with post hoc paired t tests, were used to compare the 4 throw types within pitchers.At foot contact, the participant's shoulder line was nearly horizontal when pitching from a mound and became progressively more inclined as throwing distance increased. At arm cocking, the greatest amount of shoulder external rotation (mean ± SD, 180° ± 11°), elbow flexion (109° ± 10°), shoulder internal rotation torque (101 ± 17 Nm), and elbow varus torque (100 ± 18 Nm) were measured during the maximum-distance throws. Elbow extension velocity was also greatest for the maximum-distance throws (2573°/s ± 203°/s). Forward trunk tilt at the instant of ball release decreased as throwing distance increased.Hard, horizontal, flat-ground throws have biomechanical patterns similar to those of pitching and are, therefore, reasonable exercises for pitchers. However, maximum-distance throws produce increased torques and changes in kinematics. Caution is, therefore, advised in the use of these throws for rehabilitation and training.

The overhead throwing motion is an extremely skillful and intricate movement. When pitching, the overhead throwing athlete places extraordinary demands on the shoulder complex subsequent to the tremendous forces that are generated. The thrower's shoulder must be lax enough to allow excessive external rotation but stable enough to prevent symptomatic humeral head subluxations, thus requiring a delicate balance between mobility and functional stability. We refer to this as the "thrower's paradox." This balance is frequently compromised and believed to lead to various types of injuries to the surrounding tissues. Frequently, injuries can be successfully treated with a well-structured and carefully implemented nonoperative rehabilitation program. The key to successful nonoperative treatment is a thorough clinical examination and accurate diagnosis. Rehabilitation follows a structured, multiphase approach, with emphasis on controlling inflammation, restoring muscles' balance, improving soft tissue flexibility, enhancing proprioception and neuromuscular control, and efficiently returning the athlete to competitive throwing. Athletes often exhibit numerous adaptive changes that develop from the repetitive microtraumatic stresses occurring during overhead throwing. Treatment should include the restoration of these adaptations.Level 5.

Prospective single-group repeated-measures design.To quantify electromyographic (EMG) muscle activity of the infraspinatus, teres minor, supraspinatus, posterior deltoid, and middle deltoid during exercises commonly used to strengthen the shoulder external rotators.Exercises to strengthen the external rotators are commonly prescribed in rehabilitation, but the amount of EMG activity of the infraspinatus, teres minor, supraspinatus, and deltoid during these exercises has not been thoroughly studied to determine which exercises would be most effective to achieve strength gains.EMG measured using intramuscular electrodes were analyzed in 10 healthy subjects during 7 shoulder exercises: prone horizontal abduction at 100 degrees of abduction and full external rotation (ER), prone ER at 90 degrees of abduction, standing ER at 90 degrees of abduction, standing ER in the scapular plane (45 degrees abduction, 30 degrees horizontal adduction), standing ER at 0 degrees of abduction, standing ER at 0 degrees of abduction with a towel roll, and sidelying ER at 0 degrees of abduction. The peak percentage of maximal voluntary isometric contraction (MVIC) for each muscle was compared among exercises using a 1-way repeated-measures analysis of variance (P.05).EMG activity varied significantly among the 7 exercises. Sidelying ER produced the greatest amount of EMG activity for the infraspinatus (62% MVIC) and teres minor (67% MVIC). The greatest amount of activity of the supraspinatus (82% MVIC), middle deltoid (87% MVIC), and posterior deltoid (88% MVIC) was observed during prone horizontal abduction at 100 degrees with full ER.Results from this study provide initial information to develop rehabilitation programs. It also provides information helpful for the design and conduct of future studies.

Rehabilitation specialists commonly observe upper-extremity injuries in golfers, baseball players, and tennis players. Traditional nonoperative and postoperative rehabilitation programs for these athletes involve a gradual restoration of range of motion (ROM), strength, muscular endurance, dynamic stabilization, and neuromuscular control. Upon successful completion of the early phases of the rehabilitation program, a gradual and controlled return to sport activities has been advocated by several authors. The term “interval sport programs” has been used to refer to functional rehabilitation guidelines that simulate sport activities. These programs are designed to progressively apply forces to the healing structures and are intended to gradually return the athlete to full athletic competition as quickly and safely as possible. The purpose of this paper is to describe specific interval sport programs currently utilized at our center to return golfers, baseball players, and tennis players to competition follo...

Underhand pitching has received minimal attention in the sports medicine literature. This may be due to the perception that, compared with overhead pitching, the underhand motion creates less stress on the arm, which results in fewer injuries. The purpose of this study was to calculate kinematic and kinetic parameters for the pitching motion used in fast pitch softball. Eight female fast pitch softball pitchers were recorded with a four-camera system (200 Hz). The results indicated that high forces and torques were experienced at the shoulder and elbow during the delivery phase. Peak compressive forces at the elbow and shoulder equal to 70-98% of body weight were produced. Shoulder extension and abduction torques equal to 9-10% of body weight x height were calculated. Elbow flexion torque was exerted to control elbow extension and initiate elbow flexion. The demand on the biceps labrum complex to simultaneously resist glenohumeral distraction and produce elbow flexion makes this structure susceptible to overuse injury.

Thorough descriptions of specific physical examination tests used to determine glenohumeral instability are lacking in the scientific literature. The purpose of this paper was to discuss the importance of the subjective history and illustrate the physical examination of the glenohumeral joint. Additionally, the authors will illustrate specific stability assessment for the glenohumeral joint based on current basic science and clinical research. The physical examination of a patient whose history suggests subtle glenohumeral joint instability may be extremely difficult for the clinician due to the normal amount of capsular laxity commonly present in most individuals. An essential component of the physical examination is a through and meticulous subjective history which includes the mechanisms of injury and/or dysfunction, chief complaint, level of disability, and aggravating movements. The physical examination must include an assessment of motion, static stability testing, muscle testing, and a neurologic assessment. A comprehensive understanding of various stability testing maneuvers is important for the clinician to appreciate. The evaluation techniques discussed in this paper should assist the clinician in determining the passive stability of the glenohumeral joint.

Surgical reconstruction of the anterior cruciate ligament (ACL) using a patellar tendon autograft is a common orthopaedic procedure. Complications such as arthrofibrosis, patellar fracture, significant donor site pain, and quadriceps muscle weakness can occur from this procedure. Previous studies have not documented the effects of isolated graft procurement without concomitant ligamentous reconstruction on the donor extremity. This case study documents the clinical outcome results of an individual who underwent a central one-third graft harvest from his contralateral uninjured knee for an ACL graft of his injured ACL-deficient knee. The results indicate that at 4 months following graft procurement, the knee extensors were equal to the preoperative isokinetic test results of that leg. In addition, the patient exhibited full range of motion and no patellofemoral complaints of dysfunction. At 12 months postsurgery, the graft donor leg was 5-9% stronger than the preoperative test results. The results of this case study suggest that isolated harvesting of a 10-mm central patellar tendon free graft may not result in significant quadriceps muscle weakness or contribute to donor site pain.

The American Sports Medicine Institute conducts research to increase understanding of mechanisms involved in upper extremity injuries to throwing athletes. This paper presents a qualitative overview of pitching and a detailed quantitative description of arm motion about the shoulder during this highly dynamic activity. Data on kinematics of arm motions about the shoulder are presented for 29 elite throwers. The major motion about the shoulder is external/internal rotation. Scapulothoracic and glenohumeral flexibility permit the arm to reach an externally rotated position of 175 degrees. Approximately 30 msec before release, the arm internally rotates 80 degrees, reaching peak angular velocities near 7,000 degrees/sec. In rehabilitation of injured throwers, there is a need to appreciate the highly dynamic nature of this skill and to attempt to simulate these dynamic motions and loads as part of the final phase of treatment before the athlete returns to competition.

Rotator cuff injury in athletes results from accumulation of microtrauma to both the static and dynamic stabilizers of the shoulder. Our classification of these injuries and treatment protocol is based on knowledge of the pathophysiology of events leading to rotator cuff failure. Rotator cuff disease is attributed to one of five different modes of failure: primary compressive disease, secondary compressive disease, primary tensile overload, secondary tensile overload, and macrotraumatic injuries. Although disease is categorized based on a single failure mode, there is often significant overlap between the mechanisms of injury leading to the disease. Categorization and, consequently, treatment of the injury rely upon proper identification of the primary pathology and an understanding of the causative factors leading to rotator cuff failure. In most cases conservative management is successful, but, in the refractory cases, minimally invasive surgical techniques have also been successful in returning most athletes to a premorbid level of function.

Rehabilitation following an injury to the elbow joint complex is common in physical therapy practice. The unique anatomical considerations of the elbow joint provide a significant challenge to the therapist in rehabilitating elbow injuries. The purpose of this paper is to describe the rehabilitation process for various elbow pathologies and provide a rationale for their treatment. The rehabilitation process for the injured elbow presented in this paper will emphasize phases that are progressive, sequential, and based on clinical and scientific research.

The physical examination of the thrower's elbow presents the clinician with the clinical challenge of differentially diagnosing specific pathologies. The examination should include a thorough history and a well-organized physical examination, which relies on an extensive knowledge of the functional anatomy of the elbow. The components of an elbow examination include inspection/observation, palpation of bony and soft tissues, range of motion assessment, resisted muscle testing (both manual and mechanical), neurologic testing, and special tests. The special tests commonly performed on the thrower's elbow are the Tinel test, tennis elbow sign, ulnar collateral ligament stability testing, valgus extension overload test, and radiocapitella chondromalacia test. Other tests include radiographic examination, such as computerized tomograph arthrogram and magnetic resonance imaging testing. Information presented in this paper will provide the clinician with a systematic and thorough evaluation process for the thrower's elbow.

By understanding pitching biomechanics, therapists can develop better preventive and rehabilitative programs for pitchers. The purpose of this study was to quantify and explain the joint motions, loads, and muscle activity that occur at the elbow during baseball pitching. Seven healthy, adult pitchers were examined with synchronized high-speed video digitization and surface electromyography. Elbow extension before ball release corresponded with a decrease in biceps activity and an increase in triceps activity. A varus torque of 120 Nm, acting to resist valgus stress, occurred near the time of maximum shoulder external rotation. Previous cadaveric research showed that the ulnar collateral ligament by itself cannot withstand a valgus load of this magnitude. Triceps, wrist flexor-pronator, and anconeus activity during peak valgus stress suggests that these muscles may act as dynamic stabilizers to assist the ulnar collateral ligament in preventing valgus extension overload.

Enhanced athletic performance emphasizes the muscle's ability to exert maximal force output in a minimal amount of time. Exaggerated maximal muscular force develops due to athletic movements producing a repeated series of stretch-shortening cycles. The stretch-shortening cycle occurs when elastic loading, through an eccentric muscular contraction, is followed by a burst of concentric muscular contraction. A form of exercise called plyometrics employs a quick, powerful movement involving a prestretch of the muscle, followed by a shortening, concentric muscular contraction, thus utilizing the stretch-shortening muscular cycle. The literature contains numerous references to plyometric training for the lower extremity, but there is a lack of information on the upper extremity plyometric program. Overhead activities, such as throwing, necessitate elastic loading to produce maximal, explosive, concentric muscular contractions. Plyometric exercise employs the concept of the stretch-shortening muscular cycle. The rehabilitation concept of specificity of training suggests plyometric exercise drills should be performed by the throwing athlete. This paper discusses the basic neurophysiological science and theoretical basis for plyometric exercise, and it describes an upper extremity stretch-shortening exercise program for the throwing athlete.

The purpose of this study was to compare the effects of proximal single resistance pad placement (PSPP) and distal single pad placement (DSPP) on tibial displacement during isokinetic exercise on anterior cruciate ligament (ACL)-deficient knees. This study is important to the clinician because it documents tibial displacement during open chain isokinetic knee extension exercise at various isokinetic speeds. In addition, this study documents the range of motion where the greatest amount of anterior tibial displacement occurs. The anterior displacement of the tibia was recorded by a computerized knee laxity testing device during isokinetic exercise. Data were collected from 12 ACL-deficient knees. Each subject was tested on an OSI Knee Signature System for quantifiable tibial displacement during a Lachman's test, anterior drawer test, and active vs. passive knee extension. Following this, each subject was tested on a Biodex isokinetic dynamometer at isokinetic velocities of 60, 180, and 300 degrees/sec with the computerized knee laxity testing device in place. Pad placement consisted of distal single pad placement, which is 1 inch proximal to the medial malleolus, and proximal single pad placement, which is 3 inches proximal to the DSPP location. The testing procedure was standardized, and peak torque was monitored to ensure consistent maximal effort throughout the study. The results indicated that PSPP resulted in less anterior tibial displacement at all three test speeds. The peak anterior tibial displacement occurred in a range from 30 to 15 degrees of knee flexion at both pad placements and all three test speeds.(ABSTRACT TRUNCATED AT 250 WORDS)

Presented at the Sports Physical Therapy Section Team Concept Meeting, December 1991, New Orleans, LA The manner of acquiring strength-testing data may influence the results of an investigation. The purpose of this study was to determine if a significant difference exists between windowed and unwindowed data collection during isokinetic testing of the shoulder abductors/adductors. Fifty healthy professional baseball pitchers participated in this study. Testing was performed on a Biodex isokinetic dynamometer at 180 and 300 degrees /sec for both the throwing and nonthrowing shoulders. Testing procedures regarding testing protocol, repetitions, positioning, and stabilization followed established guidelines for each subject. Statistical analysis was performed using a paired t-test with a p0.01 level of significance. Statistically significant differences were demonstrated between windowed and unwindowed mean peak torque data for both shoulders at both test speeds. The results indicated an average nonthrowing arm difference of 20.2 ft/lbs at 180 degrees /sec and 51.7 ft/lbs at 300 degrees / sec for the abductors. In each instance, the unwindowed mean peak torque values were higher than the windowed values, and significant end range torque spikes were elicited during unwindowed data collection. The nonthrowing adductors exhibited an average of 39.3 and 48.3 ft/lb differences at 180 and 300 degrees /sec, respectively. The throwing shoulder demonstrated average abductor differences of 25.6 ft/lbs at 180 degrees /sec and 47.7 ft/lbs at 300 degrees /sec. The average throwing adductor difference was 24.4 ft/lbs and 54.6 ft/lbs, respectively, at both test speeds. This investigation offers clinical relevance for those using isokinetic testing of the shoulder abductors/adductors in demonstrating the significant differences between windowed and unwindowed data, identifying torque spike data misinterpretation, and describing a clinical means of controlling aberrant torque production during testing. J Orthop Sports Phys Ther 1992;15(2):107-112.

Treatment of anterior cruciate ligament injuries has changed considerably in recent years. The purpose of this paper is to discuss the past and present treatment for anterior cruciate ligament (ACL) disruptions in athletic individuals. In addition, this paper will discuss current trends in rehabilitation, such as immediate motion, weight bearing, and close kinetic chain exercises, and provide the scientific rationale for these rehabilitation principles. The treatment of individuals who have suffered an ACL disruption has changed dramatically over the years. The treatment of ACL ruptures has made a full circle. The first reconstructive procedure described used a patellar tendon graft. Then primary ACL repairs were advocated. With the limited success of that procedure, the nonoperative treatment was popularized, with reconstruction performed only after the conservative program failed. With this treatment plan, clinicians noted early degenerative joint changes and an increase in meniscus tears in the ACL deficient knee. Thus, reconstructive surgery using a patellar tendon graft was again advocated. Today, the current trend in the treatment of ACL tears is an arthroscopically assisted procedure to reconstruct the ACL using a bone-tendon-bone graft, such as a patellar tendon. The surgery employs accurate graft placement, tensioning, and fixation, which allows the therapist the opportunity to utilize immediate motion and weight bearing, in addition to strengthening exercises. This paper attempts to explain the rehabilitation process following ACL reconstruction using current scientific and clinical research. The program is based on the anatomy, biomechanics, and healing process of the knee, joint, and ACL. The clinical implications of this paper are numerous. First, we believe the information will assist clinicians in developing their own programs. Second, the data will assist the reader in understanding the sequential healing process. Finally, this paper documents that immediate aggressive rehabilitation is not deleterious to the ACL graft, and early therapy improves the functional outcome. J Orthop Sports Phys Ther 1992;15(6):279-293.