Labral Injury and Posterior Impingement in Elite Tennis Players
The repetition of the abduction-external rotation movement of the arm during the overhead action carries an increased risk of overloading various structures around the shoulder. Pathologic contact between the posterior margin of the glenoid and the articular surface of posterosuperior rotator cuff tendons is known as posterior internal impingement. The chronic repeated compression or impingement leads to articular tears of the rotator cuff tendons as well as lesion of the superior labrum. Every overhead athlete requires a training program that strengthens all elements of the kinetic chain of the throwing motion. Patients with mild symptoms and early phases of the disorder need active rest, including a complete break from throwing along with physical therapy. Conservative management of SLAP lesions is often the first line of treatment. However, frequently, rehabilitation is unsuccessful; therefore, surgical intervention is often warranted to repair the labral lesion while addressing any concomitant pathology.
The shoulder is the most mobile joint in the human body. Its anatomical design provides stability allowing a wide range of motion in all directions. This leads to a fragile equilibrium between stability and mobility, especially in the tennis player, who is trying to generate as much energy as possible for the serving motion. The repetition of the abduction-external rotation movement of the arm during the overhead action carries an increased risk of overloading various structures around the shoulder. The cause of shoulder pain in the overhead athlete is very difficult to identify and diagnose. Pathologic contact between the posterior margin of the glenoid and the articular surface of posterosuperior rotator cuff tendons is known as posterior internal impingement (PII) [1, 2, 3]. Young overhead athletes, continuously performing high velocity throwing actions over the years, usually go to specific osseous and soft tissue adaptations. Adaptive anatomic changes in throwers athletes that can lead to internal impingement include glenohumeral internal rotation deficit (GIRD), increased humeral and glenoid retroversion, acquired glenohumeral anterior-posterior instability, scapular weakness, and concomitant rotator cuff weakness. The chronic repeated compression or impingement leads to articular tears of the rotator cuff tendons as well as lesion of the superior labrum (SLAP lesions).
14.2 Biomechanical Aspects and Pathomechanics of Posterior Impingement and Labral Injuries in Tennis Players
14.3 Posterior Impingement
14.4 Clinical Evaluation and Treatment of Posterior Impingement
Internal impingement typically affects young to middle-aged adults; in most major case series of internal impingement, patients are under 40 years of age and participate in activities involving repetitive abducting and externally rotating arm motions or positions [20, 21, 22, 23]. The majority of patients who have been identified with internal impingement are overhead athletes [24, 25]. Most patients present with a progressive decrease in throwing velocity or a loss of control and performance [10, 26, 27]. Chronic, diffuse posterior shoulder girdle pain is common in terms of the presenting complaint, but the pain may be localized to the joint line. Despite posterior shoulder pain being the most common complaint among patients with internal impingement, patients may also present with symptoms similar to those associated with classic rotator cuff disease [28, 29]. Alternatively, patients may also have instability symptoms, such as apprehension or the sensation of subluxation with the arm in an abduction and external rotation position. Burkhart et al. reported an 80% rate of anterior coracoid pain in their series of 96 athletes with a disabled throwing shoulder, rather than isolated posterior shoulder pain, described as the most common presenting symptom . Posterior glenohumeral joint line tenderness, increased external rotation, and decreased internal rotation (GIRD) are the most common physical examination findings in throwing athletes. With regard to concomitant increased external rotation, Myers et al. recently emphasized that throwers with pathological internal impingement exhibiting significantly increased posterior shoulder tightness and glenohumeral internal rotation deficits do not necessarily gain significantly increased external rotation . In addition, scapular dyskinesis is a commonly reported finding. Characteristic features include a prominent inferior medial border of the scapula and the appearance of an inferiorly dropped throwing shoulder compared to the non-throwing side . Meister et al. investigated the ability of a single maneuver, referred to as the “posterior impingement sign,” to detect the presence of articular-sided rotator cuff tears and posterior labrum lesions . The subjects were tested for the presence of deep posterior shoulder pain when the arm was brought into a position similar to that noted during the late cocking phase of throwing. The sensitivity and specificity of the posterior impingement sign were 75.5% and 85%, respectively. MRI is considered the gold standard in the work-up of any young patient presenting with shoulder pain . MR findings in internal impingement include articular-sided partial-thickness rotator cuff tears of the supraspinatus, infraspinatus, or both tendons and posterior or superior labral lesions . The tears of the rotator cuff tendons are usually small and involve the articular surface. In addition, these athletes often present with associated posterosuperior labral abnormalities. Cysts and impaction deformity are also seen at the posterior greater tuberosity and can increase diagnostic confidence in the diagnosis of internal impingement. The vast majority of shoulder injuries in throwers should initially be treated with a conservative, nonoperative regime. Only significant structural injuries such as an acute rotator cuff tear, dislocation, or SLAP lesion deserve early surgical intervention. Every overhead athlete requires a training program that strengthens all elements of the kinetic chain of the throwing motion. Patients with mild symptoms and early phases of the disorder need active rest, including a complete break from throwing along with physical therapy. Anti-inflammatory measures to “cool down” the irritated shoulder can be beneficial in accelerating the rehabilitation process. This includes nonsteroidal anti-inflammatory drugs (NSAIDs) and occasionally a corticosteroid injection. Athletes with longer-lasting problems need a rehabilitation program emphasizing dynamic stability, rotator cuff strengthening, capsular stretching, and a scapular stabilization program [5, 33, 34]. Rehabilitation program Phase 1: the primary aims of the rehabilitation program are aimed at allowing the injured tissue to heal, modification of activity, decreasing pain and inflammation, on the re-establishment of a baseline dynamic stability, correction of the muscle balance, and restoration of proprioception. In addition, the athlete’s activities (such as throwing and exercises) must be modified to a pain-free level. Active-assisted motion exercises may be used to normalize shoulder motion, particularly shoulder internal rotation and horizontal adduction. The thrower should also perform specific stretches and flexibility exercises for the benefit of the posterior capsule and rotator cuff muscles. Rehabilitation program Phase 2: the primary goals are to intensify the strengthening program, continue to improve flexibility, and facilitate neuromuscular control. During this phase, the rehabilitation program is progressed to more aggressive isotonic strengthening activities with emphasis on restoration of the muscle balance. Selective muscle activation is also used to restore muscle balance and symmetry. Contractures of the posterior structures, the pectoralis minor muscle, and the short head of the biceps muscle also contribute to a glenohumeral internal rotation deficit and increase the anterior tilting of the scapula. Borstad et al. found the “sleeper stretch” to be effective for a stretch on the posterior aspect of the shoulder . Several authors have emphasized the importance of scapular muscle strength and neuromuscular control as a contribution to normal shoulder function . Isotonic exercise techniques are used to strengthen the scapular muscles. Overhead-throwing athletes often exhibit external rotator muscle weakness. Also during this second rehabilitation phase, the overhead-throwing athlete is instructed to perform core-strengthening exercises for the abdominal and lower back musculature. In addition, the athlete should perform lower extremity strengthening and participate in a running program including jogging and sprints. Upper extremity stretching exercises are continued as needed to maintain soft tissue flexibility. Rehabilitation program Phase 3: the goals are to initiate aggressive strengthening drills, enhance power and endurance, perform functional drills, and gradually initiate throwing activities. Dynamic stabilization drills are also performed to enhance proprioception and neuromuscular control. An interval throwing program may be initiated in this phase of rehabilitation. Rehabilitation program Phase 4: this phase usually involves progression of the interval throwing program as well as neuromuscular maintenance. The goal is to return to the full throwing velocity over the course of 3 months. To prevent the effects of overtraining or throwing, it is essential to instruct the athlete what to do through specific exercises throughout the year. A lack of improvement after 3 months, or an inability to return to competition within 6 months, constitutes failure of the nonoperative conservative management and thus should result in an additional diagnostic testing, and, if necessary, operative intervention should be considered. The following arthroscopic examination is performed in terms of a systematic review of the entire shoulder. The surgeon should carefully evaluate the entire shoulder and look for evidence of instability in the biceps tendon, biceps anchor, labrum, capsule, rotator interval, and the rotator cuff insertion. Surgical intervention should be directed toward specific pathological lesions believed to correspond to the patient’s symptoms or play a role in the complex pathophysiology of internal impingement. Despite this treatment, up to 90% of the patients can be expected to have persistent pain, although to a lesser degree, while playing tennis. Furthermore, only 50% of tennis players with posterosuperior glenoid impingement surgically treated can be expected to return to tennis at their preinjury level .
14.5 Labral Injury (SLAP Lesion)
The labrum is a fibrous structure strongly attached around the edge of the glenoid that increases the contact surface area between the glenoid and the humeral head . The glenoid labrum enhances shoulder stability reducing humeral head translation, increasing the “concavity-compression” effect between the humeral head and the glenoid, increasing the overall depth of the glenoid fossa, and contributing to the stabilizing effect of the long head of the biceps anchor [36, 37, 38, 39, 40, 41]. The superior labrum is rather loose and mobile and has a “meniscal-like” aspect, while the inferior labrum appears rounded and more tightly attached to the glenoid rim. The labrum is attached to the lateral portion of the biceps anchor superiorly. Additionally, approximately 50% of the fibers of the long head of the biceps originate from the superior labrum, and the remaining fibers originate from the superior glenoid tubercle. There are several injury mechanisms that are speculated to be responsible for creating SLAP lesions. These mechanisms range from single traumatic events to repetitive microtraumatic injuries. Repetitive overhead activity is maybe the most common mechanism of injury responsible for producing SLAP injuries. Andrews et al. originally described the detachment of the superior labrum in a subset of throwing athletes in 1985 . Later Snyder et al. introduced the term SLAP lesion—indicating an injury located within the superior labrum extending anterior to posterior . They originally classified these lesions into four distinct categories based on the type of lesion present, emphasizing that this lesion may disrupt the origin of the long head of the biceps. Over time, modifications have been made to the initial classification system such that ten different types of SLAP tears have now been identified [44, 45, 46, 47, 48]. Andrews et al. first hypothesized that SLAP pathology in overhead-throwing athletes was the result of the high eccentric activity of the biceps during the arm deceleration and follow-through phases of the overhead throw [42, 49]. Burkhart et al. and Morgan et al. have hypothesized a “peel back” mechanism that produces SLAP lesion in the overhead athlete. They suggest that when the shoulder is placed in a position of abduction and maximal external rotation, the rotation produces a twist at the base of the biceps, transmitting torsional force to the anchor [48, 50]. Furthermore, Jobe and Walch et al. have also demonstrated that when the arm is in a maximally externally rotated position, there is contact between the posterior-superior labral lesions and the rotator cuff [1, 3]. A recent study conducted at the authors’ research center simulated each of these mechanisms using cadaveric models . Nine pairs of cadaveric shoulders were loaded to biceps anchor complex failure in either a position of simulated in-line loading (similar to the deceleration phase of throwing) or simulated peel back mechanism (similar to the cocking phase of overhead throwing). Results showed that seven of eight of the in-line loading group failed in the midsubstance of the biceps tendon with one of eight fracturing at the supraglenoid tubercle. However, all eight of the simulated peel back group failures resulted in a type II SLAP lesion. The ultimate strength of the biceps anchor was significantly different when the two loading techniques were compared. The biceps anchor demonstrated significantly higher ultimate strength with the in-line loading (508 N) as opposed to the ultimate strength seen during the peel back loading mechanism (202 N). In theory, SLAP lesions most likely occur in overhead athletes from a combination of these two previously described forces. The eccentric biceps activity during deceleration may serve to weaken the biceps-labrum complex, while the torsional peel back force may result in the posterosuperior detachment of the labral anchor. Several authors have also reported a strong correlation between SLAP lesions and glenohumeral instability. Normal biceps function and glenohumeral stability are dependent on a stable superior labrum and biceps anchor. Pagnani et al. found that a complete lesion of the superior portion of the labrum large enough to destabilize the insertion of the biceps was associated with significant increases in anterior-posterior and superior-inferior glenohumeral translation . Reinold et al. reported that in a series of 130 overhead athletes with symptomatic hyperlaxity undergoing thermal-assisted capsular shrinkage (TACS) of the glenohumeral joint, 69% exhibited superior labral degeneration, while 35% had type II SLAP lesions . Furthermore, Kim et al. reported that maximal biceps activity occurred when the shoulder was abducted to 90° and externally rotated to 120° in patients with anterior instability . Because this position is remarkably similar to the cocking position of the overhand throwing motion, the finding of instability may cause or facilitate the progression of internal impingement (impingement of the infraspinatus on the posterosuperior glenoid rim) in the overhead athlete.
Although this tear pattern has been described and studied for quite some time, the ideal treatment of these injuries remains elusive. Indications for operative repair remain unclear with increasing reports of complications and suboptimal outcomes within the literature [53, 54]. With the knowledge that degenerative changes of the superior labrum occur commonly with age and improvements in magnetic resonance imaging quality, SLAP tears are becoming a more frequent diagnosis. Zhang et al. recently reviewed the demographic trends of SLAP repairs in the United States using a publicly available database and found that the number of SLAP repairs significantly increased over time from 2004 to 2009 . This increase in the number of diagnosed SLAP tears that are treated with arthroscopic repair is interesting because the ideal treatment for SLAP tears has not been elucidated and several studies have shown increasing risk of complications and poor outcomes with inability to return to sport particularly in overhead-throwing athletes.
14.6 Clinical Evaluation and Treatment of SLAP Lesion
The vast majority of shoulder injuries in overhead athletes should initially be approached with a conservative treatment. Only significant structural injuries deserve early surgical intervention. Every overhead athlete requires a training program that strengthens all elements of the kinetic chain of the throwing motion. Further investigation is needed to help determine which patients are likely to succeed with nonoperative treatment and those who will predictably do well with surgical repair. Most clinical studies on this topic are from single institutions and lack the power necessary to definitively draw conclusions about the superiority of specific management options.
- 13.Myers JB, Laudner KG, Pasquale MR, et al. Posterior capsular tightness in throwers with internal impingement. Presented at the Annual Meeting of Orthopaedic Surgeons, February 23–27; 2005.Google Scholar
- 62.Kibler WB, Sciascia AD, Hester P, Dome D, Jacobs C. Clinical utility of traditional and new tests in the diagnosis of biceps tendon injuries and superior labrum anterior and posterior lesions in the shoulder. Am J Sports Med. 2009;37(9):1840–7. https://doi.org/10.1177/0363546509332505.CrossRefPubMedGoogle Scholar
- 75.Chalmers PN, Trombley R, Cip J, Monson B, Forsythe B, Nicholson GP, et al. Postoperative restoration of upper extremity motion and neuromuscular control during the overhand pitch: evaluation of tenodesis and repair for superior labral anterior-posterior tears. Am J Sports Med. 2014;42:2825–36. https://doi.org/10.1177/0363546514551924.CrossRefPubMedGoogle Scholar
- 79.Tayrose GA, Karas SG, Bosco J. Biceps tenodesis for type II SLAP tears. Bull Hosp Jt Dis (2013). 2015;73:116–21.Google Scholar