A 19-year-old, male collegiate tennis player presented to clinic with a long-standing history of stiffness and spasms throughout his spine, which has translated into his posterior shoulder and lumbar region. He had always felt “stiff throughout his back” and had tried several different forms of treatment without relief. He had a history of costochondritis and rib dysfunction without any specific mechanism of injury. The patient had an unremarkable medical history without any underlying conditions.
The patient was referred to physical therapy after a diagnosis from his team physician for a bilateral spondylolysis at L3 to L4, without any neurological signs or symptoms. Upon physical examination, he displayed a significant asymmetry in thoracic rotation toward his dominant arm, as well as global hypomobility throughout the thoracic spine. Concomitantly, the patient had acquired a bicipital tendinopathy on the ipsilateral side as the rotational asymmetry. He demonstrated poor neuromuscular control of the musculature throughout the thoracic region, particularly with the isolated extension of the midthoracic spine. The midthoracic hypomobility became increasingly evident with the trunk in a slightly extended position during standing.
The clinical hypothesis for the resulting spondylolysis etiology was a maladaptation of the lower-lumbar spine due to his thoracic hypomobility and the lack of torso rotation while serving. Compensatory movement patterns associated with his thoracic hypomobility caused an abnormal loading of the posterior elements of the lower-lumbar spine, most evident during coupled movements, such as extension with side bending and rotation. In addition to his axial examination, as previously described, a comprehensive physical examination, which included analyzing his kinetic chain (KC), was performed to identify any additional potential contributions and/or secondary effects from the peripheral joints to his spondylolysis. Following his physical examination, a plan of care was developed which addressed increasing thoracic mobility and postural reeducation. Upon discharge from formalized care, the patient had a successful return to sport, without any exacerbations during the following seasons.
Biomechanics of the Thoracic Spine/Scapulothoracic Articulation
The thoracic spine can be regarded as a near midpoint of the body, and a transition zone between the cervical and lumbar spines, housing the ribcage, and 12 vertebral segments. Due to the attachment of the ribcage, the thoracic spine is considered more rigid than the cervical or lumbar spine, particularly with movements in the sagittal plane. Approximately 80% of axial rotation originates in the thoracic spine, with decreasing range of motion (ROM) available in the lower segments (1,2). The thoracic spine also plays a prominent role in upper-extremity movement due to the various muscular attachments of the scapulothoracic (ST) articulation.
Due to the anatomical composition of this articulation, scapular and glenohumeral (GH) positioning can be affected by the resting postures of the thoracic spine (3–5). Increased thoracic kyphosis in both static and dynamic positions can alter the scapulohumeral joint kinematics, potentially leading to scapular dyskinesis, and alterations to the GH/ST ratio (3,4,6). Researchers have proposed that alterations in the GH/ST ratio can result in decreased shoulder strength and ROM, which in turn can predispose the shoulder to impingement and tendinopathies (3,6).
Chronic overuse conditions can vary between sports, as the imposed demands across all joints can impact the areas of the musculoskeletal system (7–9). Therefore, one should consider that the pathoanatomic location of the injury may be the result of impairments proximal or distal to that site (7–9). A poignant example in the literature includes low back pain in elite youth divers due to limited shoulder flexibility (9). The authors hypothesized that limitations in shoulder flexibility could cause a pathologic and injurious compensatory strategy of pathologic lumbar hyperextension during the entry phase of the dive (9).
The purpose of this article is to describe the concepts of the KC, regional interdependence (RI), and treatment(s) of the thoracic spine and its adjacent body regions, as they relate to the overhead athlete (Fig. 1). In this article, we will define the overhead athlete as anyone who participates in a sport where the arm repetitively elevates over their head. A review of the findings from the literature published over the past year (2017–2018), ranging from topics, such as thoracic mobility measurement(s), the efficacy of certain manual therapy techniques on the thoracic spine, and placebo analgesia will be discussed. Finally, the authors will provide insight on “clinical pearls” for physical examination(s) and clinical intervention(s) related to the thoracic spine in the overhead athlete.
The KC refers to the linkage of multiple joint segments, encompassing from the foot to the cervical spine, and their associated role(s) in transfer of forces to create movement (5,7,10–21). Due to its significant role in axial rotation and transverse plane motion, the thoracic spine serves as a point of transition from the lower and upper quarters (6,16). Through the identification of the interplay of the KC during dynamic, sport-related movements and in static postural assessments, clinicians can detect potential contributors to injury. The interplay is particularly important in overhead sports as the act of throwing involves a transfer of linear energy from the lower quarter to rotational energy in the upper quarter, culminating in the release of the object (12). The recognition and subsequent correction of abhorrent movement patterns within the KC during the tennis serve and baseball pitch have been integrated as part of comprehensive injury prevention programs (5,10,12,14). An example of potential distal contributors to a more proximal pathoanatomical injury can be found in the research of the association of static abnormal foot postures and their association with upper-extremity injuries requiring surgery in elite-level baseball pitchers (11). To highlight the role of the KC with respect to overhead throwers, Zaremski et al. found that more than 50% of kinetic energy that is transferred to the upper extremity is through the legs and core (10,12,17).
RI has been defined as the “concept that seemingly unrelated impairments in a remote anatomical region may contribute to, or be associated with, the patient's primary complaint” (22–24). Conceptually, RI considers the musculoskeletal and neurophysiological structures playing a role in homeostasis of the musculoskeletal system (23), with the biopsychosocial (25) and somatovisceral systems (26) as contributors. The key differential between the theories of RI and the KC is that RI is not completely rooted in the biomechanical linkages of the musculoskeletal system. As an example, the neurophysiological responses to maintain homeostasis associated with movement and injury, including those related to peripheral, central, and supraspinal mechanisms supplement the findings of a musculoskeletal and biomechanical assessment (22,27,28). Clinically, an example of the RI approach is performing a thoracic spine high-speed joint manipulation (thrust) for the neurophysiological benefits related to pain, in combination with therapeutic exercises to address musculoskeletal impairments.
Clinical Pearls and a Review of Recent Literature (2017 to current)
Before a physical examination, a detailed medical and sport-related history should be taken. As a part of the history, a key variable is the patient's perception of their condition, a description of subjective pain levels, and level of impairment. Additionally, the chronicity of the condition and any previous treatment approaches are necessary to obtain, because this can help the provider(s) achieve a successful outcome and therapeutic alignment with the patient.
When taking the history of an overhead athlete, clinicians should incorporate questions regarding the joint proximal and distal to the involved segment(s). As noted previously, when applying the concepts of the KC and RI, a multifactorial approach in the handling of a condition is medically appropriate.
For the overhead athlete, a thorough physical examination and functional assessment using task-oriented movements may uncover any of the following deficits across one or multiple regions: lack of mobility, neuromuscular control, muscular endurance, balance, and/or strength deficit. Examination should include the upper and lower quarters, axial skeleton (cervical, thoracic, and lumbar spines) and lumbopelvic-hip complex in the open and closed chain. In consideration of the overall complexity of the overhead athlete, standard testing positions also should be modified, as impairments may be present during sport-related tasks.
The examination of the thoracic spine in overhead athletes should include an assessment of its upper, middle, and lower regions and the interplay of the ST articulation. Segmental mobility can be best measured during thoracic extension and flexion while seated, with hand placements on the spinous process of each segment and along the sternum. The position described above will allow clinicians to assess whether the patient is using a compensatory fulcrum over the segment, which may indicate an undesirable hypomobility, if there is a compensatory fulcrum either above or below. With overhead athletes, it is important to assess thoracic contributions to end-range shoulder flexion and abduction, because they require normal mobility of the thoracic spine (2,5,6,10,13).
Dyskinesis of the ST articulation should be screened for using dynamic movements in both the open and closed chains. For open-chain testing, we recommend performing assessed lightly weighted scaption and large-amplitude forward/backward shoulder circles. For closed-chain assessments, we recommend beginning with a standard floor and wall push-up.
As the physical demands vary between overhead sports, so too should the clinical examination. Clinicians should consider elements of the sport to include areas, such as recognition of typical injury patterns, sport-related movement asymmetries, compensatory movement strategies, and the potential for deficits in postural endurance (5,9,15,17,29,30). An example of sport-related movement asymmetries can be seen in divers, as the authors have often observed a lack of rotation, usually contralateral to the side that they twist toward, and midthoracic extension. Of note, testing for rotational asymmetry in seated or the “lumbar-locked” position may be insufficient. The authors recommend placing them into a passively extended or flexed position while standing.
Compensatory movement strategies also have been observed by the authors in divers with diagnosed GH joint instabilities and low back pain who had hypomobility into thoracic extension. The authors suppose the lack of midthoracic extension contributes to a dyskinetic ST articulation, particularly at its inferior border. The compensatory strategy by a diver with a hypomobile midthoracic spine would likely result in promoting hypermobility through the shoulder. The dynamic stabilizers and their ability to maintain control of the ST articulation, in particular the middle and lower trapezii. should be determined (30). Additionally, the rotator cuff musculature should be strength-tested throughout a full arc of elevation or abduction for greater specificity of the overhead athlete.
Thoracic Mobility Assessment
Accurate measurement of thoracic mobility is crucial, as proper execution of overhead athletic-based movements and maintenance of proper spinal arthrokinematics are key functions of the region (2–4). Therefore, an accurate assessment of thoracic mobility is necessary. Thoracic mobility has been regarded as difficult to objectively measure and thus as highly subjective, leaving clinicians using unreliable instrumentation (1,31–34). As a result, clinicians may perform a visual analysis to assess movement of the thoracic spine. The advent of mobile technologies has provided an opportunity to conveniently and objectively measure joint mobility. Bucke et al. (1) validated a thoracic rotation measurement using a digital inclinometer (DI) and iPhone Clinometer application, in the lumbar-locked or heel-sit position in a population of self-reported healthy students (Fig. 2). The lumbar-locked position aims to minimize lumbar rotation by having the patient in quadruped with full flexion of the hips and lumbar spine. There was strong criterion validity found using the DI when compared with the reference standard (r = 0.88, P < 0.001). The iPhone Clinometer application had strong criterion validity compared with the reference standard (r = 0.88, P < 0.001). The DI and Clinometer application had strong concurrent validity (r = 0.98, P < 0.001) and could possibly be used interchangeably.
Feijen et al. (31) measured the interrater and intrarater reliabilities of the lumbar-locked thoracic rotation test, bilaterally, in a group of 21, healthy, young swimmers. The raters utilized a bubble inclinometer and were blinded to each of their findings. Results for interrater reliability ranged from 0.89 (0.72–0.95) to 0.86 (0.65–0.94), respectively, for right and left thoracic rotation. These results suggested good to excellent reliability of the lumbar-locked thoracic rotation test.
Hypomobility in thoracic extension, coupled with decreased shoulder ROM in divers, can contribute to low back pain, due to the excessive extension-moment while trying to extend the spine into the water during the entry phase (9). In a study examining spine MRIs at the 2016 Summer Olympic Games, researchers found that the highest sport-specific incidence of moderate to severe spinal disease was seen in aquatic diving athletes (29). The previously mentioned study by Narita et al. (9) found that the primary predictor for low back pain in young divers was decreased shoulder mobility.
To isolate thoracic extension during an assessment, the authors recommend several variations of the sternal lift maneuver. Clinicians should be aware that patients with hypomobile thoracic spines may substitute the movement using scapular retraction (Fig. 3). To best assess mobility using the sternal lift, instruct the patient to extend their sternum while concurrently performing a stabilizing maneuver of the lumbar spine, such as a pelvic tilt. We have included images of the sternal lift maneuver in prone, however, clinicians can modify testing positions as needed. Positions for this to be assessed can include prone, sitting, standing, or even supine. This manner of examination is clinically relevant due to the associated ROM restrictions of the shoulders with increased thoracic kyphosis.
Verifying for postural endurance of the musculature along the thoracic spine is particularly important in overhead athletes where their sport requirement includes repetitive overhead activity. For example, assessing a diver's ability to hold a sternal lift after performing several diving exercises, such as line-ups or pike-ups, is warranted. Overhead throwing and serving motions should be analyzed both before and after fatiguing the extremities.
Interventions aimed at passive and active modalities using clinical judgment that progresses patients with thoracic hypomibility are fundamental to a successful outcome. The authors recommend both clinician-guided manual therapy techniques and patient self-mobilization utilizing a foam roller or a firm ball. Patients can then be progressed to exercises such as quadruped and side-lying thoracic rotation-biased exercises. After rotational ROM is addressed, then the patient should perform sequenced sports-specific movement(s) incorporating thoracic extensor and, periscapular musculature with retraction, and then overhead elevation.
Manual therapy in combination with targeted exercises is utilized by clinicians and often prescribed by physicians for the thoracic spine (35–37). Manual therapy includes such treatment modalities, such as joint manipulation and soft tissue mobilization. The mechanisms by which manual therapy is purported to impact outcomes in patients can range from osteokinematic changes, neurophysiologic effects, and placebo analgesia (35–43).
In a published case series of seven overhead athletes, researchers sought to determine the efficacy of a manual therapy technique, the Mulligan Concept (bmulligan.com), for the thoracic spine in patients with shoulder pain and disability (38). The rationale behind the study was that secondary impingement syndrome (SIS) of the shoulder is very common in younger overhead athletes and often is accompanied by a forward flexed and kyphotic posture. The researchers applied sustained natural apophyseal glides (SNAG) as the spinal mobilization technique. Sustained natural apophyseal glides combine elements of active physiological movement with an accessory glide directed along the facet joint plane, with the goal to facilitate pain-free movement throughout the osteokinematic ROM (38). This case series is the first to utilize SNAG as an intervention for SIS. The Numeric Rating Scale was administered at initial evaluation, immediately following intervention, and at the 48-h follow-up to identify patient-reported pain during shoulder ROM activities, manual strength testing, and with special tests of the shoulder. Investigators also administered the Shoulder Pain and Disability Index at initial evaluation and the 48-h follow-up to identify patient-reported pain and the degree of difficulty during functional activities of the upper extremity. The results of this case series found that the use of thoracic SNAG in patients classified with SIS may have an impact on short-term pain and disability; however, the results did not reach the level of a clinical meaningful difference.
In a recently published systematic review with meta-analysis of randomized controlled trials, the authors sought to compare a single session of thoracic manual therapy with a placebo/sham thoracic manual treatment in patients with nonspecific shoulder dysfunction. The outcomes of pain, mobility, and function were measured at the end of the treatment session (39). The authors of this review were particularly interested in the potential of a placebo effect, as the biomechanical and neurophysiologic benefits of manual therapy are debatable. The authors concluded that a very low to low level of quality of evidence whereby a single session of thoracic manual therapy was not more effective than a sham manual therapy for pain in patients with shoulder dysfunction. However, it should be noted that the optimal number of manual therapy sessions to gain a sustained long-term change is unknown.
An alternative perspective on placebo analgesia was put forth, whereby contextual factors surrounding the experience of manual therapy may have therapeutic benefits (40). The authors' viewpoints attributed several mechanisms for placebo analgesia effects to the psychosocial context surrounding the clinical encounter. Examples within a patient encounter included the enthusiasm of the clinician to apply manual therapy interventions, perceptions of the overall experience by the patient, and the positive emotional interactions of the patient and practitioner. Placebo analgesia has a minimal impact on outcomes in placebo-controlled studies, where participants are aware at the time of consent that there is a chance of receiving a placebo treatment (41). Furthermore, placebo analgesia can be significant when the participant is provided with instructions that enhance expectation(s) (42). The authors concluded that placebo mechanisms are active neurophysiological effects generated and influenced by the expectations and the experience of receiving skilled treatment from a highly trained professional.
The thoracic spine plays a vital role in the movements of the overhead athlete. Clinicians should use reliable and valid objective measures and clinical reasoning as part of a thorough evaluation. Further insight on potential movement impairments of the thoracic spine can be gathered through a KC assessment and in applying RI to compliment the overall patient presentation. The authors believe that future research regarding examination and treatment of the thoracic spine for overhead athletes is warranted.
The authors declare no conflict of interest and do not have any financial disclosures.
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