Clinical Presentation and Diagnostic Indicators of SLAP Lesions¶
Patients with a superior labrum anterior-posterior (SLAP) lesion typically present with vague shoulder pain that is frequently exacerbated by overhead activities. This pain is often intermittent and typically occurs during specific movements rather than at rest.
Mechanical symptoms are a hallmark of the presentation, with patients often reporting a painful "catching," "popping," "locking," or "snapping" sensation in the shoulder. These symptoms often occur when an unstable labral fragment becomes trapped between the humeral head and the glenoid surface. In some cases, patients may describe a sensation of the shoulder "going out" or a subjective feeling of instability, even if objective laxity is not immediately apparent.
In the context of overhead athletes, particularly baseball pitchers, a SLAP lesion often manifests as "dead arm syndrome". This is characterised by a gradual loss of function, an inability to throw at pre-injury velocity or with previous control, and a general sense of unease in the shoulder. Importantly for those who typically work in contact sports, don't make the mistake of thinking that the "dead arm" is neurological (perhaps associated with shoulder subluxation, or shoulder depression causing brachial plexus traction), rather this is a jargon term for a marked reduction in throwing velocity associated with a perception of the shoulder no longer being "lively" or able to throw hard. Athletes frequently relate the sudden onset of searing pain specifically to the late cocking phase of the throwing motion, as the arm begins to accelerate from maximal external rotation.
Typical physical findings and associated impairments include:
• Range of motion deficits: Many athletes present with glenohumeral internal rotation deficit (GIRD), defined as a loss of internal rotation of at least 13° to 20° compared to the non-throwing shoulder.
Rotational Range of Motion in the Overhead Athlete¶
The assessment and interpretation of total rotational range of motion (ROM) in overhead athletes must account for both soft tissue adaptations and osseous changes, specifically humeral torsion (retroversion).
Assessment of Rotational ROM¶
• Positioning: The patient is positioned supine on the examination table. The shoulder is placed in 90° of abduction and the elbow in 90° of flexion.
• Stabilisation: It is essential for the examiner to stabilise the scapula to eliminate scapulothoracic motion, ensuring that only glenohumeral movement is measured.
• Measurement: A goniometer is used to quantify the maximum degrees of internal rotation (IR) and external rotation (ER). The sources also define "neutral rotation" as the point where the bicipital groove aligns with the anterior edge of the acromion.
Interpretation and the Influence of Humeral Torsion¶
Interpretation of these measurements requires a distinction between advantageous adaptations and pathological deficits:
Osseous Adaptation:¶
Repetitive throwing often leads to increased humeral retroversion (torsion). This bony change provides a "protective shift" of the throwing arc, resulting in an increase in external rotation and a natural decrease in internal rotation compared to the non-dominant side.
The "Shoulder at Risk"¶
180° is common, but not universal total rotational ROM¶
"The 180° Rule":¶
Traditionally, if the total arc of motion (the sum of external and internal rotation measured passively at 90° of abduction in supine) is less than 180°, the shoulder is considered a "shoulder at risk" for developing "dead arm syndrome" or posterior superior SLAP lesions. A deficit in the total arc of motion of as little as 5° has been shown to increase injury risk in professional pitchers. It should be noted that this value depends on: the individual's tissue laxity, the willingness of the individual to allow their shoulder to be rotated, and the willingness of the examiner to push the shoulder to true end range. Accordingly, more reliability and validity can be found when side-to-side differences for a given individual are considered, rather than an arbitrary cut-off of 180°.
Knowledge Check
Traditionally, if the total arc of motion is less than 180°, the shoulder is considered "at risk" for developing dead arm syndrome or SLAP lesions. However, side-to-side differences are more clinically relevant than this arbitrary cutoff.
GIRD vs. Total Arc Deficit:¶
Glenohumeral internal rotation deficit (GIRD) is defined as a deficit in internal rotation of at least 13° to 20° compared to the contralateral side. When interpreting GIRD, clinicians must determine if it is due to bony retroversion (where the total arc is preserved) or pathological posterior capsular contracture (where the total arc is reduced).
The sources suggest that while humeral torsion explains the shift in the arc of motion, it should not result in a loss of the total arc. Therefore, a significantly reduced total rotational ROM is typically indicative of posterior shoulder tightness rather than just osseous torsion
Scapular dyskinesis:¶
Patients may exhibit scapular winging or abnormal scapular rhythm during arm movement, often linked to posterior capsule tightness and periscapular muscle weakness.
Mimicking other pathologies:¶
SLAP lesions frequently masquerade as subacromial impingement or rotator cuff disease; many patients receive an initial preoperative diagnosis of impingement based on positive Neer or Hawkins signs.
• Tenderness: Clinicians may find tenderness to palpation at the rotator interval or immediately proximal to the supraspinatus insertion.
The mechanism of injury described by patients can vary between acute trauma, such as a fall onto an outstretched arm (compression force), and chronic repetitive loads associated with overhead sports (traction or "peel-back" forces). While some patients report a single traumatic event like a dislocation or a sudden pull on the arm, others may have an insidious onset where no specific mechanism can be determined.
Diagnosis is further complicated by the high incidence of concomitant injuries, such as partial-thickness rotator cuff tears or Bankart lesions, which can add symptoms of night pain, weakness, and instability to the clinical picture
Clinical Management and Surgical Protocols for SLAP Lesions¶
The management of superior labrum anterior-posterior (SLAP) lesions in athletes follows a structured pathway that prioritises nonoperative rehabilitation before considering surgical intervention, particularly as surgical outcomes for elite throwers are often unpredictable.
1. Initial Nonoperative Management¶
Nonoperative management is the recommended first line of treatment for all athletes with SLAP lesions, typically lasting three to six months.
Pharmacotherapy:¶
Initial care involves rest from provocative activities combined with nonsteroidal anti-inflammatory drugs (NSAIDs). Corticosteroid injections may be utilised to manage acute pain flares.
Rehabilitation Algorithm: Physical therapy focuses on resolving modifiable impairments, specifically:
Rotational Range of motion Normalisation:
Establishing if the athlete has an increase or decrease in external and/or internal rotational ROM, and then addressing this is an important first step in conservative care. Shoulder rotational range of motion can be increased with a combination of passive stretching, and eccentric overload exercise, preferably in outer ranges, while reducing range of motion can be achieved by high volume concentric exercises.
◦ Scapular Re-education: During shoulder strengthening exercises, if there is a proven link between scapular movement and symptom provocation, then adjusting the athlete's technique will be an important addition to allow the exercises to be performed acceptably, and achieve their goals (typically increasing tissue capacity).
◦ Kinetic Chain and Strengthening: Programs include core and lower extremity stabilisation alongside rotator cuff and periscapular strengthening.
• Graduated Return: Once pain is resolved and motion is restored, athletes progress to a slow graduated throwing program, typically initiated around three months.
2. Indications for Surgery¶
Surgical intervention is considered only after the failure of a 3- to 6-month nonoperative trial. Key indications include:
• Persistent pain during overhead activity despite documented improvements in flexibility.
• Mechanical symptoms such as painful catching, popping, or locking that impede performance.
• The inability to return to the desired level of competitive play.
3. Surgical Options by Lesion Type¶
Treatment is dictated by the specific type of SLAP lesion identified during diagnostic arthroscopy.
• Type I: These lesions involve degenerative fraying and are generally managed with simple arthroscopic debridement back to a stable labral rim.
• Type II: The most common subtype in athletes, treated via arthroscopic repair using suture anchors. For posterior subtype II lesions, a specialised "Port of Wilmington" (posterolateral acromial portal) is used to ensure the correct angle for anchor placement to resist peel-back forces.
• Type III: Characterised by a bucket-handle tear with a stable biceps anchor; the unstable fragment is resected or excised.
• Type IV: Management depends on the degree of biceps involvement. If less than 30% of the tendon is involved, the fragment is debrided; if more extensive, biceps tenodesis or tenotomy is preferred over repair, especially in older or high-demand patients.
• Concomitant Procedures: Surgeons may also perform a posterior capsular release for refractory tightness or an anterior capsular plication if subtle instability is present.
4. Postoperative Rehabilitation and Return to Play (RTP)¶
Postoperative care is phased and time-based, though individual recovery times vary.
• Phase I (Protection): The shoulder is immobilised in a sling for three to four weeks. For Type II repairs, passive external rotation is strictly limited (often to 0°) for the first three weeks to prevent premature torsional stress on the repair.
• Phase II/III (Motion and Strength): Strengthening for scapular stabilisers begins immediately, but aggressive biceps strengthening is avoided for 12 weeks.
• Return to Sport: A formal interval throwing program usually begins at four to five months. A return to unrestricted competitive overhead sports typically occurs between 6 and 12 months post-surgery.
5. Management Outcomes¶
Athletes should be counselled that while functional satisfaction is high (approx. 80%), regaining pre-injury performance is challenging. In professional pitchers, the rate of "Return to Prior Performance" (RPP)---defined as returning to the same competitive level with pre-injury statistics---may be as low as 7% after surgical repair. Position players generally have higher successful return rates than pitchers
Knowledge Check
In professional pitchers, the rate of Return to Prior Performance after SLAP repair may be as low as 7%, highlighting the challenging nature of returning to pre-injury statistics despite generally high functional satisfaction rates.
Suprascapular Nerve Compression in SLAP Lesions¶
Suprascapular nerve involvement in athletes with SLAP lesions is typically caused by the formation of a ganglion cyst (specifically a spinoglenoid cyst), which develops when joint fluid escapes through the labral tear into the surrounding tissues, similar to parameniscal cysts in the knee. As the suprascapular nerve has a small, almost non-existent sensory distribution (primarily motor to infraspinatus) the patient will rarely present until the consequences of this weakness manifest in secondary pathology.
The clinical presentation of this condition is characterised by the following:
• Rotator cuff weakness: The most prominent symptom is weakness with external rotation of the shoulder.
• Muscular atrophy: Physical examination may reveal ipsilateral atrophy of the rotator cuff muscles, particularly the infraspinatus. This occurs because the cyst compresses the suprascapular nerve as it passes through the spinoglenoid notch.
• Atypical pain patterns: While the underlying SLAP lesion typically causes vague shoulder pain and mechanical symptoms such as popping or catching during overhead activity, the added nerve compression primarily manifests as objective motor deficits and muscle wasting.
• Scapular dysfunction: If significant periscapular muscle atrophy or winging is observed, clinicians must also ensure there is no associated cervical spine injury.
To confirm suprascapular nerve involvement, clinicians should use MRI to detect the presence of a supraglenoid or spinoglenoid cyst. Additionally, electrodiagnostic testing (EMG) of the suprascapular nerve is recommended to objectively evaluate the extent of the neuropathy, although in practice this is technically extremely difficult to do, and the results will rarely change your diagnosis assuming you have infraspinous identified atrophy and the presence of a SLAP lesion. Management typically involves arthroscopic debridement or decompression of the cyst in conjunction with the repair of the primary SLAP lesion.