Karen J. Mohr

The Effect of Pitching Biomechanics on the Upper Extremity in Youth and Adolescent Baseball Pitchers

Background Increased pitch counts have been linked to increased complaints of shoulder and elbow pain in youth baseball pitchers. Improper pitching mechanics have not been shown to adversely affect the upper extremity in youth pitchers. Hypothesis The correct performance of 5 biomechanical pitching parameters correlates with lower humeral internal rotation torque and elbow valgus load, as well as higher pitching efficiency, in youth and adolescent pitchers. Study Design Descriptive laboratory study. Methods In sum, 169 baseball pitchers (aged 9-18) were analyzed using a quantitative motion analysis system and a high-speed video while throwing fastballs. The correct performance of 5 common pitching parameters was compared with each pitchers age, humeral internal rotation torque, elbow valgus load, and calculated pitching efficiency. Results Motion analysis correlated with video analysis for all 5 parameters (P <. 05). Youth pitchers (aged 9-13) performing 3 or more parameters correctly showed lower humeral internal rotation torque, lower elbow valgus load, and higher pitching efficiency (P <. 05). Conclusions Youth pitchers with better pitching mechanics generate lower humeral internal rotation torque, lower elbow valgus load, and more efficiency than do those with improper mechanics. Proper pitching mechanics may help prevent shoulder and elbow injuries in youth pitchers. Clinical Relevance The parameters described in this study may be used to improve the pitching mechanics of youth pitchers and possibly reduce shoulder and elbow pain in youth baseball pitchers.

Outcome of Type II Superior Labral Anterior Posterior Repairs in Elite Overhead Athletes Effect of Concomitant Partial-Thickness Rotator Cuff Tears

Background: There are conflicting reports in the literature regarding the outcome of superior labral anterior posterior (SLAP) repairs in overhead athletes and a paucity of data demonstrating ability to return to prior level of competition. Hypothesis: Kerlan-Jobe Orthopaedic Clinic shoulder and elbow score provides more accurate assessment of shoulder function and ability to return to previous level of athletic competition after SLAP lesion repair than does the conventional American Shoulder and Elbow Surgeons scoring system. Study Design: Cohort study; Level of evidence, 3. Methods: Twenty-three elite (collegiate or professional) overhead athletes who were more than 1-year status postarthroscopic repair of type II SLAP lesions were evaluated using both the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow score and American Shoulder and Elbow Surgeons score. P values were computed using the analysis of variance model. Postoperative American Shoulder and Elbow Surgeons and Kerlan-Jobe Orthopaedic Clinic scores from subjects were compared with control values obtained from a healthy athletic cohort; the relationship between the scores was investigated using the linear regression model and assessed using Pearson correlations. Results: At a mean 38-month follow-up, 13 athletes were playing pain free at the time of the questionnaire administration, 6 were playing with pain, and 4 were not playing because of pain. Regarding American Shoulder and Elbow Surgeons scores, 22 athletes (96%) had good-excellent scores, whereas 1 (4%) had a fair score. The Kerlan-Jobe Orthopaedic Clinic scores revealed 9 excellent (39%), 3 good (13%), 4 fair (17%), and 7 poor (30%) results for the same study group. Of the 23 patients, 13 (57%) had returned to their pain-free preinjury levels of competition at final follow-up. The inability to return to this level of competition correlated with the presence of a partial-thickness rotator cuff tear (P = .0059). The Kerlan-Jobe Orthopaedic Clinic demonstrated better overall accuracy (85%) than did the American Shoulder and Elbow Surgeons (70%) in evaluating return to pain-free preinjury levels. Conclusion: Return to preinjury level of competition for elite overhead athletes after type II SLAP lesion repairs was 57%, despite high American Shoulder and Elbow Surgeons scores. Return to play status correlated with the presence of a partial-thickness rotator cuff tear. The Kerlan-Jobe Orthopaedic Clinic score, designed specifically for the evaluation of the overhead athlete, was a more accurate assessment tool than was the American Shoulder and Elbow Surgeons in this population of elite overhead athletes with SLAP tears.

The Development and Validation of a Functional Assessment Tool for the Upper Extremity in the Overhead Athlete

Background There are no validated upper extremity instruments designed specifically to evaluate the performance and function of overhead athletes. Current shoulder and elbow scoring systems may not be sensitive to subtle changes in performance in this high-demand population. Hypothesis The scoring system developed in this study will be valid, reliable, and responsive in the evaluation of overhead athletes. Study Design Cross-sectional study; Level of evidence, 3. Methods Based on the results of a pilot questionnaire administered to 21 overhead athletes, a final 10-item questionnaire was developed. Two hundred eighty-two healthy, competitive overhead athletes completed the new questionnaire, as well as 2 established upper extremity questionnaires, and were self-assigned into injury categories: (1) playing without pain, (2) playing with pain, and (3) not playing due to pain. Correlations between the scores and differences between injury categories were measured. Responsiveness testing was performed in an additional group of 55 injured athletes, comparing their scores before and after an intervention. Results The new score showed high correlation with the Disabilities of the Arm, Shoulder and Hand (DASH) score and the DASH sports/performing arts module. The new score correctly stratified overhead athletes by injury category (P < .0001). The new score also demonstrated excellent responsiveness, varying appropriately with improvements in injury category after treatment of injuries (P < .05). Conclusion The new patient-reported instrument is valid and responsive in the evaluation of overhead athletes. Reliability was also demonstrated for the 13-item pilot questionnaire. The results support its use for the functional assessment of overhead athletes in future studies.

Disorders of the Superior Labrum: Review and Treatment Guidelines

Advancements in shoulder arthroscopy have led to a better understanding of the anatomy and disorders of the superior labrum biceps tendon anchor complex and the role that lesions of the superior labrum anterior and posterior lesions play in pain and instability of the shoulder. Various injury mechanisms have been suggested and studied and it is likely that different mechanisms produce different types and areas of damage to the superior labrum. Classification systems have been proposed to describe the specific pathoanatomy of lesions of the superior labrum anterior and posterior lesions and to guide treatment. Presenting symptoms often are nonspecific and physical examination maneuvers have varying degrees of sensitivity and specificity making diagnosis challenging. Diagnostic ability is enhanced by the ultimate diagnostic test, arthroscopy. A clear appreciation for the various lesions and the potential resulting joint dysfunction is necessary to determine the appropriate treatment of this complex region of the shoulder. The current authors review the anatomy, classification, presentation, evaluation and treatment results of superior labrum anterior and posterior lesions, and includes novel evaluation methods and treatment guidelines useful in treating these lesions.

The Effects of Home Interferential Therapy on Post-Operative Pain, Edema, and Range of Motion of the Knee

ObjectiveWe studied the effects of home interferential current therapy (IFC) on postoperative pain, range of motion, and edema in subjects undergoing anterior cruciate ligament (ACL) reconstruction, menisectomy, or knee chondroplasty. DesignRandomized, double-blind, placebo-controlled prospective study. SettingA tertiary care outpatient orthopaedic clinic/ambulatory surgery center. Subjects or ParticipantsEighty-seven subjects were separated into three groups based on their type of knee surgery and within each group randomized into a treatment or placebo group. InterventionsAll subjects received home IFC units. Subjects randomized to treatment group received a working IFC unit. Placebo subjects received units that were previously set to deliver no current. Main Outcome MeasurementsPost-operative edema at 24, 48, and 72 hours, and weeks 1-8; range of motion at 1, 3, 6, and 9 weeks; pain immediately after surgery, at 24, 48, and 72 hours, and weeks 1-7; and amount of pain medication taken at days 1-10 were compared between treatment and placebo groups. ResultsAll IFC subjects reported significantly less pain and had significantly greater range of motion at all post-operative time points. ACL and menisectomy IFC subjects experienced significantly less edema at all time points, while chondroplasty subjects experienced significantly less edema until 4 weeks postoperatively. ConclusionsThese findings indicate that home IFC may help reduce pain, pain medication taken, and swelling while increasing range of motion in patients undergoing knee surgery. This could result in quicker return to activities of daily living and athletic activities.

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation.

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

Clinical Follow-up of Professional Baseball Players Undergoing Ulnar Collateral Ligament Reconstruction Using the New Kerlan-Jobe Orthopaedic Clinic Overhead Athlete Shoulder and Elbow Score (KJOC Score)

Background: There are no validated outcome measures consistently used in the literature to report results of ulnar collateral ligament reconstruction in overhead athletes. Hypothesis: The Kerlan-Jobe Orthopaedic Clinic Overhead Athlete Shoulder and Elbow score (KJOC score) will correlate with other validated scores for upper extremity assessment but will be more accurate in evaluating ulnar collateral ligament reconstruction outcomes in professional baseball players. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Fifty-five professional baseball players who underwent ulnar collateral ligament reconstruction were asked to complete the KJOC score, the Disabilities of the Arm, Shoulder and Hand (DASH) score, and the DASH sports module. Players were separated into 3 categories—(1) playing without pain, (2) playing with pain, and (3) not playing because of pain—and compared with 123 asymptomatic throwers. Pearson (parametric) and Spearman rank (nonparametric) correlations among the 3 systems were conducted to validate the KJOC score. Means across categories were compared using a Wilcoxon rank-sum test, and a threshold score separating categories 1 and 3 was determined using receiver operator characteristic discrimination analysis. Results: Significant correlations were found between the KJOC score and the DASH (−.693, P < .0001), and the DASH sports module (−0.804, P < .0001). Only the KJOC score was able to discriminate between categories 2 and 3, as well as category 1 and the uninjured population. In addition, the KJOC score was the most sensitive and accurate method of discriminating category 1 from category 3, with a threshold score of 81.3. Conclusion: The results of this study validate the use of the KJOC score for evaluation of overhead athletes undergoing ulnar collateral ligament reconstruction. The KJOC score is the most sensitive score for detecting subtle changes in performance in the throwing athlete.

The Effect of Tennis Racket Grip Size on Forearm Muscle Firing Patterns

Background Inappropriately sized tennis racket grip is often cited in the popular media as a risk factor for overuse injuries about the forearm and elbow. Currently, a hand measurement technique developed by Nirschl is commonly used by tennis racket manufacturing companies as the method for determining a players “recommended” grip size. Hypothesis Quarter-inch changes from that recommended by Nirschl in tennis racket grip size will have no significant effect on forearm muscle firing patterns. Study Design Controlled laboratory study. Methods Sixteen asymptomatic Division I and II collegiate tennis players performed single-handed backhand ground strokes with rackets of 3 different grip sizes (recommended measurement, undersized 1/4 in, and oversized 1/4 in). Fine-wire electromyography was used to measure muscle activity in extensor carpi radialis longus and brevis, extensor digitorum communis, flexor carpi radialis, and pronator teres. Repeated-measure analysis of variance was used for within-group comparisons, comparing different grips in specified phases for backhand ground strokes (P [.lessequal]. 05). Results There were no significant differences in muscle activity between small, recommended, or big grips in any muscle tested. Conclusion Based on these findings, tennis racket grip size 1/4 in above or below Nirschls recommended measurement does not significantly affect forearm muscle firing patterns. Clinical Relevance Alterations in tennis racket grip size within 1/4 in of Nirschls recommended sizing do not have a significant effect on forearm muscle activity and therefore may not represent a significant risk factor for upper extremity cumulative trauma, such as lateral epicondylitis.

Electromyographic Analysis of Forearm Muscles in Professional and Amateur Golfers

Background No fine-wire electromyography studies have been performed to compare the activity of forearm muscles in professional golfers versus amateur golfers. Hypothesis The fine-wire electromyographic activity of forearm muscles differs between professional and amateur golfers during the different phases of the golf swing. Study Design Controlled laboratory study. Methods Ten male right-handed amateur golfers and 10 male right-handed professional golfers without history of elbow symptoms were tested with fine-wire electromyographic electrodes inserted into the flexor carpi radialis, pronator teres, flexor carpi ulnaris, and extensor carpi radialis brevis muscles of both forearms. Electromyographic data were synchronized with video data, and the muscle activity was expressed as a percentage of maximum manual muscle test activity for each phase of the golf swing. Results Compared with professional golfers, amateur golfers had more muscle activity in the pronator teres of the trail arm (right arm in a right-handed golfer) in the forward swing phase (120.9% maximum manual muscle test vs 57.4% maximum manual muscle test; P =. 04) and a trend toward increased activity in the acceleration phase (104.8% maximum manual muscle test vs 53.1% maximum manual muscle test; P =. 08). In contrast, professional golfers had more muscle activity in the pronator teres of the lead arm (left arm in a right-handed golfer) in the acceleration phase (88.1% maximum manual muscle test vs 36.3% maximum manual muscle test; P =. 03) and a trend toward increased activity in the early follow-through phase (58.1% maximum manual muscle test vs 28.8% maximum manual muscle test; P =. 06). Conclusion Pronator teres muscle activity in the golf swing differs significantly between professional and amateur golfers. Clinical Relevance Exercises with an emphasis on stretching and strengthening of the pronator teres may be useful in treating and/or preventing medial epicondylitis in amateur golfers.

Electromyographic investigation of stretching: the effect of warm-up.

Objective:To compare the fine wire electromyographic (EMG) firing patterns during static stretches in the biceps femoris, soleus, and gastrocnemius before and after warm-up as well as over time. Design:Experimental single group pretest-posttest design. Setting:Biomechanics research laboratory. Participants:Sixteen healthy volunteers 23 to 36 years of age with no history of lower extremity injury. Intervention:Subjects performed one hamstring stretch and four calf stretches for 90 seconds, bicycled for 30 minutes as a warm-up, and stretched again. Main Outcome Measure:EMG was recorded at time 0, 30, 60, and 90 seconds during the stretches before and after warm-up. Recorded values were normalized to EMG during maximum manual muscle testing (MMT). A two-way analysis of variance with repeated measures (p < 0.05) was done to compare EMG activity during stretching before and after warm-up as well as over time. Results:Low EMG activity was seen for all muscles (<20% MMT). It was constant over the time of the stretch for all muscles, but it increased in the soleus during the bent knee stretch position. There was a statistically significant decrease in the EMG activity after the warm-up for the gastrocnemius using the traditional and heel off stretching positions and for the soleus using the heel off stretching position (p < 0.05). The biceps femoris EMG activity showed no significant differences before and after warm-up. Conclusions:EMG activity during static stretching was low. Overall, the EMG activity remained constant with time for a given stretch position. EMG of the soleus and gastrocnemius was significantly less after warm-up for some stretches, whereas the EMG activity of biceps femoris showed no differences before and after warm-up.