The shoulder joint is undoubtedly one of the most interesting joints in the human body. Although we are anatomically adapted to bipedal locomotion through evolution, demands on the shoulder joint can be massive. In particular, increased demands are observed in physical activities where movement is primarily performed with the upper limbs.
Although shoulder joint impairments are very broad, there is particular interest in the different types of difficulties experienced by female and male sexes. In addition to biomechanical demands on the shoulder joint, female athletes have hormonal influences on the shoulder. Indeed, hormonal changes occurring during the menstrual cycle directly affect the soft-tissue structures of the shoulder joint and may contribute to increased mobility. Thus, due to the specific biological and biomechanical aspects of the female sex, we observe their greater susceptibility to certain orthopedic injuries, including shoulder joint injuries (Wessel et al., 2021).
Together, let's first explore this joint in general, then take a closer look at the specificity of shoulder joint issues in the female population.
1. Anatomy and kinesiology
The shoulder joint is a type of so-called free ball and socket joint. Anatomically, it is composed of 3 bones, namely: the humerus, the clavicle and the scapula. It is the most mobile joint in the human body which brings with it a number of great advantages, but also noticeable disadvantages.
Stabilization of the shoulder joint itself is ensured, first and foremost, by the muscles and their tendons that adjoin the joint capsule. Ligaments also contribute to stability of the joint. The muscles that aim to maintain stability in the shoulder joint are collectively called the rotator cuff muscles. These muscles include: supraspinatus, infraspinatus, teres minor (all from the back of the shoulder), and subscapularis (from the front). The individual ligaments of the shoulder joint then help to strengthen and stabilise the joint capsule. Anatomically, according to the literature, the coracohumeral ligament and glenohumeral ligaments are included here.
The movement of the shoulder itself is mediated by three ‘true’ articulations and two specific ‘false’ articulations. The true articulations ensure synergy of the bony segments while the false articulations provide increased mobility of the entire shoulder segment. The false articulations are helped by connective tissues like fascia. The false articulations also give the joint the specificity of movement already mentioned. Thanks to this mobility, the shoulder joint holds the aforementioned first place as the most mobile joint of the human body.
For accuracy and a better understanding of the shoulder joint, we list below all the articulations involved in the shoulder:
- Glenohumeral joint
- Acromioclavicular joint (called AC joint)
- Sternoclavicular joint (called SC joint)
- Scapulothoracic joint – not a true joint
- This articulation is made by sliding the scapula across the thorax with the help of interlocking connective tissue.
- Subacromial space - not a true joint
- This connection is between the acromion and the head of the humerus. It is made with the help of a sparse ligament and together with a bursa they fill the space in the joint capsule.
Figure 1: Articulation of the brachial plexus (taken from:Healthy Street - THE FIVE JOINTS OF THE SHOULDER )
If we want maximum range in the shoulder joint without overloading it, we need to maintain mobility of all articulations in the shoulder joint. Although the movements in some of the joints mentioned are quite minimal, they are very important for the physiological functioning of the shoulder joint. It is possible to perform physiological movement in the shoulder joint in three planes, namely movements in the frontal, transverse and sagittal planes (Kolář, 2020).
In a physiological situation, ranges of up to 150°-170° can be achieved in the shoulder joint during shoulder flexion and 40° during shoulder extension. Horizontal flexion of the arm reaches a range of 130° to 160°, and horizontal extension 40° to 50°. Abduction of the arm should be around 180°, and adduction between 20° - 40°. The ranges of rotation in the joint are conditioned by the position of the humerus relative to the trunk, i.e. the degree of adduction (Kolář, 2020).
When performing physical activity, we use a combination of all types of movements mentioned above. The shoulder joint is so complex that the optimal execution of these movements also requires appropriate alignment of the head, trunk and pelvis. Thus, the view of the shoulder joint cannot only be local, but global. Additional focus on structures of the human body more distant to the shoulder is necessary to understand any problems in the shoulder, even if at first glance these structures do not seem to play a role in the problem of the joint (Kolář, 2020).
2. Functional examination and the Painful arch - Arch of Cyriax
Diagnosis of shoulder joint problems is in general a rather complicated matter. As we announced in previous chapters, hormonal influences add to this complexity for female athletes, which expands the portfolio of possible causes of difficulties. Within the examination of the shoulder joint we have a wide range of specific diagnostic tests available which fall under the remit of trainers. In the following chapters, we will review together some simple laws that can help you in the assessment of deviations taking place in the shoulder in your normal coaching practice - however, it is always necessary to subsequently contact a specialist who has experience in the field (Kolář, 2020).
In a visual examination, we use a basic view of the position of the shoulders and shoulder blades at rest. It is also advisable to look at the entire posture of the participant. One common deviation in a dominant number of cases is a protracted posture of the shoulders, which is most often due to increased tension of the pectoral muscles. In the case of the shoulder blades, we commonly see excessive deviation to the sides of the trunk. This may be caused by laxity of the rhomboid muscles (Kolář, 2020).
We can also perform and evaluate the scapulohumeral rhythm by observing the movement of the scapula in relation to the movement of the arm during upper limb abduction. Ideally, the entire rhythm within the arm and scapula should be in a 2:1 ratio from a neutral arm position. Thus, in the case of an active arm abduction of up to 90°, the first 60° of abduction should be purely in the glenohumeral joint, the remaining 30° being accompanied by the scapula moving into external rotation. In the case of humeroscapular rhythm dysfunction, we usually see a faster onset of scapular rotation at lower degrees of upper limb abduction. This specific sign can often reveal problems with the shoulder joint, but a deviation of the rhythm does not necessarily indicate ongoing pathology. A disturbance in rhythm may instead represent an imaginary raised index finger, pointing to the possible future development of shoulder joint problems due to potential overuse. Particular care should be taken in this case in sportsmen and women who place extreme loads on the upper limbs as part of their sport (Kolář, 2020).
Figure 2: Humeroscapular rhythm (boneandspine.com)
The last diagnostic tool of possible shoulder joint disorders that we will present here is the Cyriax painful arc test. In order to perform the test correctly, we ask the athlete to perform maximum possible abduction at the shoulder joint, preferably up to 180°. The actual movement into abduction should be performed slowly and smoothly. If pain is experienced during testing, it should be registered and the angle at which the pain occurs during abduction should be noted. According to the degree of abduction at which the pain occurs, we can consider the following issues:
- Pain up to 30° of abduction → indicates possible pathology in supraspinatus.
- Pain between 30°- 60° of abduction → indicates possible pathology of the subacromial bursa.
- Pain occurring between 60° and 120° of abduction is typically indicative of possible rotator cuff damage.
- In case of onset of pain only at the maximum of the physiological movement of the upper limb into abduction, i.e. around 180°, we speak of AC (acromioclavicular) joint involvement.
3. Etiology and risks of shoulder joint disorders
3.1 Risk factors
In order to target therapy and maximize its effectiveness, it is undoubtedly necessary to know the primary cause of shoulder pain. If therapy does not address the origin of the problem, any therapeutic approaches and treatments aimed at reducing pain will almost never have a long-term effect.
In order to prevent the onset of difficulties in the first place, it is also necessary to know the risk factors for possible onset. Athletes who exhibit any of the risk factors and play sports that place high demands on the upper limbs should be targeted in training. Subsequently, it is advisable to eliminate other possible undesirable influences that could contribute to the overloading of the joint - for example, a team physiotherapist can help with this.
The risk factors are almost identical across genders, with a few that are slightly more common in the female population. Below are the risk factors that the available studies agree on and that are common to all athletes regardless of gender, according to Palmer et al. (2003) and Tooth et al. (2020).
- limited range of motion in the joint
- weakened rotator cuff muscles
- excessive training load
- dysfunction of scapular movements
All of these factors contribute to the increased incidence of shoulder joint problems in athletes. For many readers, it may certainly seem strange to include smoking as a direct risk factor - but according to many studies, smoking, among other things, has a negative impact on the soft tissues of the body (i.e. muscles, ligaments, tendons, etc.). At the same time, studies show that smokers have up to 7 times higher incidence of impingement syndrome, which is one of the most common shoulder disorders across the population. Furthermore, smoking itself significantly slows down tissue regeneration and repair, thus impacting the healing process (Palmer et al., 2003; Tooth et al., 2020).
Within the female athlete population, we must not overlook two major risk factors that play a significant role in the mechanism of joint disorders. These include specifically (Hinds et al., 2019; Posekana, 2019):
- menstrual cycle and hormonal changes.
The aforementioned factors playing a non-negligible role in the incidence of injury in female athletes will be discussed in more detail below.
3.1.1 Hypermobility in women
The term hypermobility means an increased range of joint mobility in both passive and active movement. Increased range above the physiological limit is found not only in normal ranges of motion, but also in ‘joint play’ – i.e. in the context of gentle passive joint flexibility that cannot be imitated by active movement.
In general, hypermobility can be divided into compensatory, post-traumatic, neurological deficit, and constitutional hypermobility, the last of which we consider to be central to this topic about the female shoulder. Constitutional hypermobility is characterized by an increase in joint ranges above normal throughout the body. The etiology of the occurrence is unclear, but hormonal changes participate in the changes in tissue quality.
The available studies agree on a higher incidence of constitutional hypermobility in women than in men, up to a ratio of 2:1. Constitutional hypermobility is found in almost 40% of the female population. It is more common in younger girls, but as they age, many of them correct the condition.
One test to detect constitutional hypermobility is a simple trunk flexion with the knees extended. After performing the maximum possible trunk flexion, the examiner measures the distance between the 3rd finger of the hand and the ground. A distance of up to 10 cm from the ground is considered physiological; the ability of the subject to place the entire palm of the hand on the ground may be considered a sign of hypermobility. In rare cases, we can see that the subject places the entire forearm on the ground, this result then indicates a significant ligamentous disorder. However, in order to globally label an individual as hypermobile, more specialized testing is required.
Hypermobility has been associated with up to 3 times higher odds of shoulder injury in athletes, which highlights the need for preventative strategies in hypermobility-affected individuals (Liaghat et al., 2021).
3.1.2 Menstrual cycle and hormonal changes
Changes in the levels of female sex hormones across the menstrual cycle cause fluctuating changes in ligament properties. In particular, qualitative changes occur with the degree of laxity. Increased looseness at certain stages of the cycle leads to a higher risk of injury.
Knowledge of the menstrual cycle and its individual effects is extremely important for female athletes, especially because of the need to respect the phases of the cycle, which entail a certain specificity in training.
As we mentioned above, within the phases of the menstrual cycle there is differential action of individual hormones that have a direct influence on the strength of the ligaments and soft tissues as a whole. Heitz et al. (1999) report that the effect of sex hormones on joint ligament laxity is lowest during the menstrual phase. Gradually thereafter, production increases and reaches its maximum during the luteal phase where the ligament is significantly more fragile and therefore more predisposed to injury. This theory is shared by Park et al. (2009) who further describe an increase in looseness and decrease in stiffness of the articular connections during the ovulatory phase compared to the follicular phase. The highest risk of injury then correlates directly with the maximum concentrations of oestradiol production, the peak of which is found in the phase just before ovulation (Posekana, 2019). It can therefore be interpreted that the risk of injury to the ligament or other soft tissues is quite high at this time.
The above mentioned information should be taken into account when creating a training and conditioning plan for female athletes. The above mentioned aspects of the cycle should also be kept in mind when planning sufficient recovery for female athletes - especially during the riskier phases of the cycle.
A related but no less important topic is the use of hormonal contraceptives (HC) and their effect on the soft tissues of female athletes. The use of HC and its impact on the female body is a highly debated topic overall. Overlooking the side effects that HC use can certainly bring with it, according to available studies HC use has a relatively positive effect on soft tissues. According to a study by Möller-Nielsen and Hamma (1989), women using HC have been shown to have fewer traumatic injuries. By using artificially adjusted hormone levels, women taking HC are not simultaneously exposed to the otherwise physiological increase in connective tissue laxity in the preovulatory phase (Lee et al., 2014).
Evidence of the considerable influence of hormonal changes on the shoulder joint in women can also be provided by the so-called frozen shoulder syndrome. This syndrome is characterized by significant pain, with a marked and rapid progression of the condition with a significant restriction of range of motion in the shoulder joint. The occurrence of this symptomatology is often attributed, among other things, to hormonal changes. For this reason, we see a relatively frequent occurrence of frozen shoulder syndrome in women during menopause, wheren there are significant changes in the hormone ratio (Fields et al., 2019; Pilatova 2020).
4. The most common types of shoulder joint damage
The dominant mechanism of shoulder injury in canoe slalom is repetitive elevation, i.e. repeatedly raising the arm above the horizontal. This movement imposes a number of biomechanical demands on the joint and consequently carries the risk of developing specific impairments. When these biomechanical demands are compounded by constitutional hypermobility, which as mentioned above is more dominant in women, the risk of shoulder joint problems increases.
Below is a list of the most common shoulder joint issues that can be encountered in female water polo/canoe slalom athletes.
4.1 Impingement syndrome
The term impingement can be loosely translated as pinching. It can be understood as painful soft tissue compression - specifically, compression of one or more soft tissue structures (ligaments, tendons, bursae). Most often then, we see compression of the supraspinatus tendon and the subacromial bursa, which arises as a result of tissue pressure on the inferior surface of the anterior process of the scapula (on the acromion) (Kolář, 2020).
Pain in impingement syndrome typically occurs when the arm is abduction between 70° and 120°. Pain is particularly accentuated during loading, but also persists in the phase after loading (Kolář, 2020).
As already mentioned in the functional examination chapter, one of the important aspects for proper function of the shoulder joint is the appropriate alignment of the joint in its socket. We have discussed above, for example, the importance of the position of the shoulder joints and the importance of their overall alignment within the body as a whole. If we see a protracted posture of the shoulder joints in an athlete, there will likely be more overloading of the shoulder joint due to the higher biomechanical demands placed on the joint in this suboptimal position (Kolar, 2020).
Another cause of impingement syndrome may be a disturbance in scapulohumeral rhythm due to impaired muscle coordination and timing of individual muscle involvement (Kolář, 2020).
4.2 Rotator cuff syndrome (injury)
Rotator cuff syndrome is closely related and directly linked to impingement syndrome. In rotator cuff syndrome, the rotator cuff muscles often rupture as a result of chronic overuse of the muscles. Chronic overloading of the muscles in such a demanding sport as canoe slalom often results in degenerative changes of the tendons and microtraumas in the soft tissues of the rotator cuff muscles. Without proper, frequent, and targeted training and recovery of these muscles, rotator cuff syndrome ensues. Acute rupture is very rare and is typically the result of a chronic problem that caused development of difficulties in the joint (Kolář, 2020).
Pain is described as chronic both during exertion and at rest. However, the predominant problem is active joint mobility. Often in the syndrome we first see a noticeable reduction in trophism of the deltoid muscle (Kolář, 2020).
4.3 Rupture of the tendon of the long head of the biceps
Rupture or tear of the biceps long head tendon is most often caused by a degenerative process in the biceps tendon. We can then encounter both partial rupture, when there is only a partial disruption of the integrity of the tendon, and total rupture of the tendon, when there is a complete interruption of its continuity. Typically, the damage is manifested by pain in the anterior aspect of the shoulder, which occurs mainly when the arm is extended while the upper limb is flexed at the elbow joint. Ultrasound examination typically shows swelling over the tendon and demonstrable inflammation. The quality of involvement of the lower scapular fixators and globally the whole involvement of the trunk stabilization system is a significant problem in the development of the syndrome (Kolář, 2020).
4.4 SLAP lesions
A SLAP lesion is understood as a detachment of the ligamentous cartilaginous lamina in the shoulder joint (called the glenoid labrum). The labrum has a stabilizing function in the shoulder joint - specifically, it helps to secure the humeral head in the socket of the joint. In the SLAP lesion, we can see tearing of both the anterior and posterior part of the labrum itself, with the tear occurring most often at the point of attachment of the biceps longus tendon (Kolář, 2020).
This pathology is often observed in athletes performing overhead activities - i.e. activities in which the upper limbs are repeatedly moved above the level of the head. This type of movement is typically seen in canoe slalom racers, who perform it almost constantly. At the moment when the rotator cuff fails to coordinate the movements in interaction with other muscles that should function as a unit, the humeral head is not sufficiently centred in its socket and the head then repeatedly strikes the upper part of the cartilaginous rim. Cracks can then form here and the labrum can be torn (Kolář, 2020).
The occurrence of a SLAP lesion as a separate trauma is very rare, and in 88% of cases it occurs concurrently with or as a result of other ongoing shoulder joint pathology (such as our examples of impingement and rotator cuff syndromes). However, it is important to note that the SLAP lesion is usually the primary cause of pain that ultimately leads individuals to seek professional help (Wilk, 2009; Manske, 2010; Castagna et al., 2016).
4.5 AC joint arthrosis
AC joint arthrosis falls under non-inflammatory degenerative processes in its clinical picture. Arthrotic joint processes are especially observed in chronically stressed joints. The process of arthrosis at the acromioclavicular joint can be seen especially in sportsmen and women who load the shoulder, e.g. repeatedly lifting heavy loads, throwing, or falling on the shoulder. Repeated micro-traumas caused by overloading also result in instability of the joint. The resulting instability then gradually leads to damage of the cartilage itself and accelerates the whole process of arthrosis (Kolář, 2020).
A typical symptom of this pathology is the development of pain during maximum abduction, i.e. in the range of about 180° of abduction of the arm. Patients also complain of pain in the shoulder when touching their other shoulder - this movement is therefore also used diagnostically, specifically the so-called scarf test. The test is performed either by inviting the patient to actively perform this movement or by passively guiding him/her to the same position. If the patient indicates pain, we can consider the test positive - but it is always necessary to distinguish other possible causes that could be causing the pain. At the same time, the manifestations of pain must be consistent with the clinical picture of the arthrosis and must always be consistent with the patient's other complaints. It is therefore advisable that the final diagnosis be made and confirmed by an appropriate specialist (Kolář, 2020).
5. Differential diagnosis of the shoulder joint
Within the last chapter, we will look at some examples in which shoulder joint difficulties may be caused by seemingly more distant structures of the body. Indeed, certain body segments can irritate the shoulder joint in the event of a deviation, just as pathologies arising directly in the shoulder area can. The shoulder can also be a projection of visceral (organ) irritation.
The projection of pain to the shoulder joint can often be related to the following issues (Kolar, 2020):
- blockages of the 1st-4th ribs
- irritation of the cervical vertebrae C3 - C7
- cervical-thoracic spine transition blockade (C/Th transition)
- limitation of thoracic spine mobility
- transmitted organ pain of gallbladder, spleen, heart, stomach and liver
- muscle trigger points (TrPs) typically from the rotator cuff muscles
- retracted thoracic and dorsal fascia.
The aim of the whole text, besides increasing the knowledge of shoulder problems, is also to highlight the complexity of the whole issue. Diagnosis of the shoulder joint and subsequent targeted and effective management is a very complicated matter. Therefore, it is very important that as many people as possible are informed about the basic problems of the shoulder, especially those who are closely involved in the training of athletes. However, it is always important to remember the complexity of this issue and to refer your mentee to a specialist afterwards. This way, a competent expert can objectively evaluate your suspicion, possibly add further examinations, and rule out other possible causes that could be involved in the development of the issue. Only in this way can the treatment be completely targeted and fully effective in the long term, which is the most important thing for all of us.
The article can also be downloaded here: Problematics of shoulder joint.pdf
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