Elbow injuries in the throwing athlete. Difficult diagnoses and surgical complications.

Elbow injuries in throwing athletes can be challenging from the diagnostic and management perspectives. The stress of repetitive throwing does predispose athletes to certain conditions with which treating clinicians need to be familiar. An understanding of the anatomy of the elbow and the biomechanics of throwing is essential to making the correct diagnosis and instituting proper care. Failure of nonoperative measures often requires surgical intervention. A thorough understanding of the anatomy and the spectrum of conditions that can occur is needed before decisions regarding surgical management can be made. The operative approach to elbow pathology, whether performed open or arthroscopically, should be completed by orthopedists who have experience with the clinical conditions and the appropriate technical facility to provide comprehensive care. This article has reviewed the anatomy, biomechanics, and spectrum of conditions that affect throwing athletes' elbows as well as the potential complications that can be associated with surgical management.

Electromyographic analysis of the deltoid and rotator cuff muscles in persons with subacromial impingement.

The purpose of this study was to compare subjects with subacromial impingement and subjects with normal shoulders with respect to muscle activity. Fifteen subjects in each group were studied by means of fine-wire electromyography. The middle deltoid and rotator cuff muscles were evaluated during isotonic scaption from 30 to 120 degrees. Overall, the impingement group demonstrated decreased mean muscle activity in comparison with the group of normal subjects. The magnitude of diminished activity was statistically significantly different (P < .05) during the 30- to 60-degrees arc for the infraspinatus, subscapularis, and middle deltoid muscles; in addition, the infraspinatus muscle demonstrated significantly depressed activity during the 60- to 90-degrees arc. In the impingement group, the supraspinatus and teres minor revealed a diminution of muscle function in comparison with shoulders in the normal group; the difference was not significant. This study demonstrates that muscle activity in subjects with impingement is most notably decreased in the first arc of motion. Also of clinical relevance is the fact that the inferior force vector (from the infraspinatus and subscapularis) is less functional in subjects with impingement than is the superior compressive vector (from the supraspinatus). Thus, humeral head depression during the critical first portion of elevation may be insufficient in people with subacromial impingement.

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.

Shoulder reaction time and muscle-firing patterns in response to an anterior translation force.

The primary restraint preventing humeral head translation is the capsuloligamentous system. Muscle forces can also decrease translation; however, the timing and magnitude of muscle response has not been previously reported. Fine wire electromyographic analysis of the biceps long head, anterior deltoid, pectoralis major, latissimus dorsi, and rotator cuff muscles was performed after an anterior translation force was applied to 15 normal shoulders. The reflex response time (time to 5% maximal muscle test), the protection response time (time to 20% maximal muscle test), the duration of the protection response, and the magnitude of the protection response were calculated. The shoulder reaction data showed 2 consistent patterns. Activation of the anteriorly located muscles preceded the posteriorly located muscles, and the rotator cuff muscles fired with greater magnitude than the more peripherally located muscles.