What Came First: Chicken or Egg? The Role of the Scapular Musculature in Lateral Epicondylalgia.

Written by:

Alexa B. Smith OTD, OTR/L

Virtual Hand to Shoulder Fellow '22/'23

Lateral elbow pain, commonly known as “tennis elbow,” is a common diagnosis seen throughout rehabilitation centers across the globe and one that often comes with ambiguous treatment guidelines for clinicians. Lateral epicondylalgia (LE) is defined as pathology at or near the lateral epicondyle of the humerus resulting in pain, tenderness, and functional limitations. Pathology is believed to result from overloading the common wrist extensors, particularly the extensor carpi radialis brevis (ECRB), where they insert on the lateral epicondyle of the humerus (Day, Lucado & Uhl, 2019). The term epicondylalgia (suffix algia meaning pain) is used in this context, as opposed to epicondylitis, to highlight the true histological features of the tendon, including a population of fibroblasts, disorganized collagen, and an absence of inflammatory cells. The term epicondylalgia encompasses all forms of pain at the lateral epicondyle without assuming the underlying pathology (Waugh, 2005).

While many therapeutic interventions for this condition center at the level of the elbow, including eccentric exercise, manual therapy/manipulation, orthoses, ultrasound, and multimodal physiotherapy treatment, the evidence for these treatments are still varied and often lack efficacy (Bisset & Vicenzino, 2015). Due to the weak and varied supporting evidence for current treatment options that target local pathology of the common extensor tendon, clinicians and researchers are now looking outside the level of the elbow for more clues on possible risk factors for the development of LE and later treatment of the condition. There is now debate as to whether the scapula and its musculature play more of a role in the development and later treatment of lateral elbow pathology than was previously thought. To understand this, we must first understand the kinetic chain of the upper extremity, and how a weak chain link can cause deficits further down the line.

The concept of the kinetic chain was originally developed in the field of engineering in the late 1800s. The idea was that “in a system fixed at both ends with a series of overlapping segments connected by joints, an applied force will transfer to adjacent segments in a chain reaction” (Wang, 2019). Applying the concept to the human body, if one component of the upper extremity is not functioning at normal rates the remaining parts must compensate. This then begs the question: could weak proximal scapular muscles potentially lead to muscular compensation at the wrist extensors with upper extremity performance that ultimately results in tendon damage at the lateral epicondyle origin?

The scapula, for the purpose of our metaphor, is the first link to consider in the kinetic chain. The position of the scapula as it sits in the shoulder girdle is crucial to how the remainder of the upper extremity performs in physical activities. In a retracted position (normal distance at 9 cm between the spinous processes and the medial border of the scapula), the scapula modifies the position of the humerus as to externally rotate with the cubital fossa facing anteriorly (Bhatt, et al., 2013). This places the forearm in a neutral or slightly supinated position which is functional for gripping and lifting tasks. If we consider the inverse positioning (protracted scapula, internally rotated humerus with cubital fossa facing anteromedial, pronated forearm), we could visualize how this now changes the kinesiology of a physical task as to place the wrist extensor wad in the driver’s seat. Any loss of the ability to maintain scapular retraction and normal upper extremity kinesiology may make an individual more likely to compensate proximal weakness with distal structures to complete everyday tasks.

The scapular musculature, including the upper, middle, and lower trapezius, serratus anterior, and rhomboids, play a large role in stabilizing the scapula and maintaining humeral alignment in preparation for tasks such as grasping and lifting that occur at distal segments (Bhatt, et al., 2013). Although scapular weakness may go undetected for some time, it can and should be assessed by a therapist during an initial evaluation for a diagnosis of lateral epicondylalgia. While there are many known evidence-based assessments and special tests for lateral elbow pain, a new body of research today focuses on the importance of evaluating, interpreting, and treating scapular muscular strength in the context of a diagnosis of lateral epicondylalgia.

When comparing scapular musculature strength, endurance, and change in thickness from resting to contraction, Day, et al, found that serratus anterior (SA), lower trapezius (LT), and middle trapezius (MT) strength, endurance, and change in SA muscle thickness in patients with LE were significantly less than those in the matched comparison group (2015). The authors indicate that a focus on scapular stabilizers may impact the therapeutic outcomes of LE and even have an impact on future recurrent rates. Even if the proximal weakness did not precede the development of LE, it would certainly impact prognosis in the future. Successful outcomes only at the level of the elbow may eliminate the subjective pain the patient experiences; however, with continued proximal weakness, the kinetic energy will continue to be transferred to distal segments and further predispose patients to reinjury (Day et al., 2015).

Bhatt, et al. corroborates these findings based on a 10-week program designed to strengthen only the scapular adductors (MT and LT) in a patient with chronic lateral elbow pathology (2013). The program consisted of 5 sessions in which education regarding exercises were performed at the 1st visit; additional visits were to ensure the patient was executing exercises appropriately. Exercises were performed in prone first with a short lever arm for resistance completing 3 sets of 10 twice a day; the exercises were then progressed to a long lever arm for increased resistance. At the end of the 10 weeks, the patient’s DASH score dropped from 44.2 to 0 and the patient’s pain level was at a steady 0 by session 5. The resting position of the scapula was altered by 2 cm following the program which brought it closer to midline and equal to the patient’s non-affected UE at 9 cm. Regarding the strength of the individual muscles, the strength of the MT and LT at the end of the program were 5/5 from an initial 3+/5 and 4-/5, respectively. Grip strength also reached a 38% increase compared to session 1 (Bhatt, et al., 2013). Based on the data these studies provide, we must consider how this can inform our therapeutic evaluation and treatment of this diagnosis.

While researchers are unable to definitively determine if scapular weakness leads to the development of LE or if the development of LE leads to global deconditioning from non-use, there is acknowledgement that the positioning of the scapular and the strength of its stabilizers have an effect on the distal segments when performing functional activities. With this in mind, it would be beneficial for clinicals to screen scapular muscle strength when evaluating a patient for LE to determine if intervention is warranted. Traditional treatment for LE including eccentric exercise, manual therapy/manipulation, orthoses, ultrasound, and multimodal physiotherapy treatment at the level of the elbow have been researched for many years and though the evidence for clinical use is varied, these have become known as the go-to treatment options for LE (Bisset & Vicenzino, 2015). As the evidence base continues to grow, scapular stabilizer strengthening may soon fit the mold to what we know now as ‘traditional’ and serve as another tool in our toolbox when treating the LE patient population.

References

Bhatt, Jiten B., et al. "Middle and lower trapezius strengthening for the management of lateral epicondylalgia: a case report." Journal of orthopedic & sports physical therapy 43.11 (2013): 841-847.

Bisset, Leanne M., and Bill Vicenzino. "Physiotherapy management of lateral epicondylalgia." Journal of physiotherapy 61.4 (2015): 174-181.

Day, Joseph M., Ann M. Lucado, and Timothy L. Uhl. "A comprehensive rehabilitation program for treating lateral elbow tendinopathy." International journal of sports physical therapy 14.5 (2019): 818.

Day, Joseph M., et al. "Scapular muscle performance in individuals with lateral epicondylalgia." Journal of orthopedic & sports physical therapy 45.5 (2015): 414-424.

Wang, D. D. A. (2019, November 7). An overview: The kinetic chain -. HSS Playbook Blog. Retrieved January 26, 2023, from https://www.hss.edu/playbook/an-overview-the-kinetic-chain/

Waugh, Esther J. "Lateral epicondylalgia or epicondylitis: what's in a name?." Journal of orthopedic & sports physical therapy 35.4 (2005): 200-202.