Alterations in Scapular Kinematics with Distal Radius Fracture

Research Review: Alterations in Scapular Kinematics with Distal Radius Fracture

By Jinny McGivern PT, DPT, Certified Yoga Instructor

Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Ayhan, C., Camci, E., & Baltaci, G. (2015). Distal radius fractures result in alterations in scapular kinematics: A three-dimensional motion analysis. Clinical Biomechanics. ABSTRACT

Image courtesy of http://www.raleighhand.com/online-courses/online-courses/cms/patient-information/patient-education-topics/distal-radius-fracture

X-ray of a non-displaced distal radius fracture (not treated with an internal fixation).

Image courtesy of http://www.raleighhand.com/online-courses/online-courses/cms/patient-information/patient-education-topics/distal-radius-fracture

Why is this relevant?: This research provides evidence to support the concept of the entire upper extremity as a interconnected kinetic chain. The impact of scapula position and orientation on more distal segments, such as the shoulder, is a frequent topic of discussion within the realms of human movement science. The reverse connection is not often explored. This research examines the impact of distal injuries on the movement patterns of the scapula. In the introduction to the paper, Ayhan et al (2015) report that it is not uncommon for individuals with distal injuries to go on to develop pathology of the shoulder (impingement, rotator cuff tears, etc). It is imperative that the human movement professional consider the entire upper extremity, even when an injury may only have occurred at a distal segment.

Study Summary

Relationship of movement between the scapula & humerus during elevation of upper extremity. Image courtesy of https://www.studyblue.com/online-courses/online-courses/notes/note/n/shoulder-girdle/deck/5358276.

Review & Commentary:

The authors of this research examined a unique question that has not previously been explored in the literature. There were many strong points to their methodology. They utilized a method of skin marker fixation which had been previously validated against bone affixed markers. One researcher affixed all sensors, enhancing the reliability of the readings. The distal radius fracture (DRF) group was compared against a control group. Often in cases of unilateral injury researchers may be tempted to use the subject's uninjured arm as a control. Ayhan et al. (2015) recognized that the injury that resulted in fracture may have affected both sides of the body (although there wasn't obvious pain or injury on the "unaffected" side).

There are limitations to this research. There was a lack of age & gender matching between the DRF & CON groups. It is possible that some of the alterations in scapula kinematics may be related to compensations that tend to occur with aging (or in the advanced stages of Upper Body Dysfunction - more info below in the section "How does this relate to Brookbush Institute content?"). Future research should include age, gender and activity matched controls. It would have been helpful if information could have been provided on any differences in the position of the scapula in a relaxed standing position, between groups. The researchers started to collect data at 30 degrees of elevation and ended data collection at 30 degrees of lowering. Many of us spend a large part of our day with our arms by our sides, whether we are typing in sitting or standing comfortably. These resting positions may be a place to begin re-training of a more optimal scapula position via patient education. Future research should explore differences in scapula posture in resting between those with and without DRF. Last, it would have been beneficial if EMG analysis of key muscles such as the infraspinatus, teres minor, subscapularis, supraspinatus, rhomboids and serratus anterior and trapezius were coupled with motion analysis to provide information on what may be the cause of changes in scapula kinematics.

Why is this study important?

This study provides information on regional interdependence between wrist and scapula dysfunction, although it is not surprising to find that individuals with a history of distal radius fractures demonstrated greater anterior tipping and internal rotation of the scapulae. These two actions, or changes in action are often seen in individuals with shoulder pathology. It was particularly interesting to see excessive upward rotation  considered a dysfunction, as this motion is often limited or missing in those with scapular dyskinesis; replaced with excessive elevation and/or downward rotation. This research does remind us that dysfunction can travel in both directions, proximal to distal, as well as distal to proximal. We often observe that reduced upward rotation of the scapula results in compensations /dysfunction at the glenohumeral joint (i.e. impingement). The authors of this research hypothesize that dysfunction at the glenohumeral joint, particularly inferior glide (whether inferior capsule shortening preventing movement, or rotator cuff dysfunction resulting in reduced dynamic inferior glide), may result in a scapula compensation with excessive upward rotation during arm elevation. More research is needed to fully understand this relationship.

How does it affect practice?

This study emphasizes the importance of considering the entire kinetic chain of the upper extremity even though there may only be obvious injury or dysfunction at 1 segment.

How does this relate to Brookbush Institute content?

This research supports the predictive model of Upper Body Dysfunction (UBD) as described by the Brookbush Institute. This model describes an excess of internal rotation, anterior tipping, and downward rotation as typically occurring dysfunctional scapula joint actions. This research aligns with this model for two out of the three motions: internal rotation & anterior tipping . There is a lack of congruence  related to upward versus downward rotation. In the article describing UBD , the concept that this dysfunction develops over a period of time on a continuum is presented. It is possible that all dysfunctional motions may not be present immediately. The researchers in this study propose that the observed scapula dysfunction occurred after distal radius fracture, which occurred approximately 6-8 weeks prior. It is possible that excessive downward rotation is a compensation that had not yet developed in this time period.

An interesting idea that comes out of this study relates to the sequencing of our activation exercises for the serratus anterior (scapula upward rotation ) and for infraspinatus/teres minor (shoulder external rotation & humeral head depression). The authors hypothesize that a lack of inferior humeral head translation results in excessive upward rotation of the scapula in order to maintain optimal alignment of the humerus in the glenoid fossa as the arm is moving through elevation. Based on this, it would seem wise to sequence external rotation activation before serratus anterior activation in order to ensure optimal, not excessive, recruitment of this muscle. More research with EMG data is needed to fully flesh out this concept, but it may be an activity worth trying with your clients and patients. Videos below review scapula joints & muscles, then describe shoulder external rotation and serratus anterior activation sequences. The activation techniques below should be performed after release, stretch & mobilization techniques to inhibit those muscles that are short and over-active and return normal mobility (i.e. Pec Minor Release to reduce excessive anterior tipping).

Scapular Joints and Muscles

Shoulder External Rotator Isolated Activation

Shoulder External Rotator Activation Progression

Serratus Anterior Isolated Activation

Serratus Anterior Activation Progressions

Shoulder External Rotator Reactive Activation

Serratus Anterior Reactive Activation

© 2014 Brent Brookbush

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