Similarities in the neural control of the shoulder and elbow joints belie their structural differences

The Impact of Tennis and Golfer's Elbow on Shoulder External Rotators and Abductors' Peak Torque

CONTEXT

Upper limb activities require a repetitive movement of the shoulder external rotator and abductor muscles. The malfunction of the proximal part of the upper limb kinetic chain tends to change the mechanics of the distal part and increase the risk of injuries.

OBJECTIVES

To compare the normalized eccentric peak torque (NEPT) of the shoulder external rotator and abductor muscles among healthy athletes and those with tennis elbow and golfer's elbow.

DESIGN

An experimental cross-sectional study.

SETTING

Isokinetic laboratory, Faculty of Physical Therapy, Cairo University.

PARTICIPANTS

A total of 30 male athletes participated voluntarily in this study.

INTERVENTION

Participants were distributed into 3 groups: healthy group, tennis elbow group, and golfer's elbow group.

MAIN OUTCOME MEASURES

NEPT of shoulder abductors and external rotators. The Biodex Isokinetic Dynamometer was used to measure the variables of interest.

RESULTS

There was a significant increase in the NEPT of shoulder abductors and external rotators in healthy control group compared with both tennis elbow and golfer's elbow groups at an angular velocity of 60°/s (P < .05). Moreover, there was a significant increase in the NEPT of shoulder external rotators and abductors at an angular velocity of 120°/s in healthy control group compared with tennis elbow group and in golfer's elbow group compared with tennis elbow group (P < .05).

CONCLUSION

Tennis elbow and golfer's elbow are associated with decreased NEPT of shoulder external rotators and abductors compared with those of healthy athletes. This tends to decrease the external stability of the shoulder joint and put high stress on the distal joints of the upper kinetic chain.

Shoulder and elbow joint position sense assessment using a mobile app in subjects with and without shoulder pain - between-days reliability

OBJECTIVES

To determine between-days reliability and the minimal detectable change for shoulder and elbow joint position sense assessment using a validated mobile app, in subjects with and without shoulder pain.

DESIGN

Reliability study.

SETTING

Clinical measurement.

PARTICIPANTS

Subjects with (n = 25) and without shoulder pain (n = 29).

MAIN OUTCOME MEASURES

Subjects were assessed by the same examiner in two sessions, with one-week interval. Active joint repositioning tests of shoulder flexion and scaption and elbow flexion were assessed at the target-angles of 50°, 70°, 90° and 110°. Intra-class correlation coefficient, standard error of measurement and minimal detectable change were calculated for constant, absolute, total and variable errors.

RESULTS

Good to excellent reliability was found for constant, absolute and total errors at the target-angle of 50° of scaption for healthy subjects; at 110° of shoulder flexion and all target-angles for elbow for both groups.

CONCLUSIONS

The mobile app is a reliable tool and may be useful for assessing shoulder joint position sense mainly at 110° of flexion and for elbow between 50° and 110° of flexion in subjects with and without shoulder pain. Minimal detectable changes were demonstrated and may help clinicians to follow-up rehabilitation and researchers to interpret findings of studies.

The shoulder and elbow joints and right and left sides demonstrate similar joint position sense

Proper orientation of the shoulder and elbow is necessary for accurate and precise positioning of the hand. The authors' goal was to compare these joints with an active joint position sense task, while also taking into account the effects of joint flexion angle and arm dominance. Fifteen healthy subjects were asked to replicate presented joint angles with a single degree of freedom active positioning protocol. There were no significant differences in angular joint position sense errors with respect to joint (shoulder vs. elbow) and side (left vs. right). However, when considering linear positioning, errors were lower for the elbow, due to a shorter lever arm. Also, as flexion angles increased toward 90°, there was a consistent pattern of lower errors for both joints.