Shoulder Arthroscopy (Cadaver)

Abstract

Shoulder arthroscopy is one of the most common procedures performed in orthopaedic surgery. It can be utilized to identify various pathologies including rotator cuff tears, degenerative arthritis, subacromial impingement, and proximal humeral fractures. With continued advancement in arthroscopy, patients benefit from smaller incisions, reduced risk of postoperative complications, and faster recovery compared to open surgery. Shoulder arthroscopy is performed either in the lateral decubitus position or in the beach chair position (BCP) as seen in this video. The BCP provides greater benefits such as decreased neovascularization during portal placement, fewer cases of neuropathies, and reduced surgical time. In addition to position, there are various portals used in shoulder arthroscopy, with the posterior portal being the most common and used in this video. Complication rates from shoulder arthroscopy are low but include shoulder stiffness, iatrogenic tendon injury, and vascular injury. Therefore, proper patient selection, patient positioning, and appropriate portal selection are essential for successful shoulder arthroscopy. Here, we discuss the shoulder arthroscopy and demonstrate the technique on a cadaver shoulder.

Keywords

Orthopaedics; rotator cuff; acromion.   

Case Overview

Before pursuing a shoulder arthroscopy, a thorough history and physical exam should be obtained for proper patient selection. Obtaining the history of present illness should focus on gathering information about the location of the injury and how it occurred. A focused physical exam with special maneuvers should be used to localize the injured joint or tendon, and confirmed with imaging. Proper patient positioning and portal selection is vital before starting the arthroscopy. Here, we demonstrate the beach chair position (BCP) technique with a posterior portal entry for the shoulder arthroscopy on a cadaver shoulder.

Questions to Ask while Conducting the History

• Where is the location of the pain?
  • This helps localize the pathology to the anterior, posterior, or lateral shoulder.  
• When was the onset of the pain?
  • This is to determine whether it is acute or chronic.
• Was there a predisposing injury or trauma?
• Is there pain with motion?
• Is there an equal range of motion on both sides?
• Is there partial (subluxation) or complete (dislocation) instability? What is the direction of the instability?
  • Anterior and posterior dislocations are most likely due to trauma. Multidirectional instability is due to repetitive microtrauma, commonly seen in overhead athlets, or due to genetic conditions affecting connective tissue, particulary ligaments.²²
• What is the patient’s occupation? How is the shoulder used in daily activities?
• Has there been a previous shoulder injury or surgery?
• Does the patient have any chronic conditions such as osteoporosis?
  

Physical Exam

Tips for Conducting the Physical Exam

• Visually inspect the shoulder for skin changes, scars, swelling, symmetry, and scapular winging.
• Palpate the acromioclavicular (AC) joint and surrounding bony prominences. Palpate the deltoid, trapezius, rotator cuff, and biceps tendons.
• Check the active and passive range of motion (flexion, extension, abduction, adduction, internal and external rotation).
• Special tests:¹
  • Neer impingement sign: Place one hand on the patient’s scapula and use the other hand to take the patient's internally rotated arm by the wrist and place it in full flexion. This will test for shoulder impingement or rotator cuff tear.
  • Jobe’s test: Have the elbow in full extension with the shoulder abducted 90 degrees and horizontally adducted 30 degrees. Then internally rotate the arm and press down while the patient resists. Weakness or pain indicates supraspinatus weakness or impingement.  
  • Hawkins-Kennedy Test: Performed by flexing the patient’s shoulder and elbow to 90 degrees, then internally rotating the arm. A positive test, indicated by pain during internal rotation, suggests impingement of the supraspinatus tendon or subacromial bursa.
  • Yocum’s Test: During the test, the patient places their hand on the opposite shoulder and raises their elbow without moving the shoulder. A positive test, indicated by pain during the maneuver, suggests the presence of  shoulder rotator cuff impingement.
  • Patte’s Test: During the test, the patient’s arm is elevated to 90 degrees in the scapular plane with the elbow flexed at 90 degrees. The examiner then applies an internal rotation force to the forearm, and the patient is asked to resist this movement by externally rotating the shoulder. A positive test is indicated by pain or significant weakness, suggesting a potential tear in the rotator cuff, specifically the teres minor and infraspinatus.
  • The Lift-Off Test: Assesses the subscapularis muscle by having the patient place their hand on their lower back and lift it away. A positive test, indicated by an inability to lift the hand or significant weakness, suggests a subscapularis tendon tear.
  • The Palm-Up Test: Evaluates the long head of the biceps tendon. The patient extends their arm forward with the palm up while the examiner applies downward resistance. Pain in the bicipital groove indicates a positive test, suggesting biceps tendon pathology.
• Imaging should include anteroposterior (AP) and axillary views of the shoulder to assess for anterior or posterior dislocations and Hill Sachs lesions.² Coronal CT scans can be used to identify fractures while axial CT scans can visualize reverse Hill Sachs lesions. MRI scans are utilized to assess for soft tissue injuries such as a full-thickness rotator cuff tear.³

Natural History

The shoulder allows for a great range of motion with a tradeoff for a lack of stability, which predisposes to various injuries. The major joints of the shoulder include the AC, sternoclavicular, scapulothoracic, and glenohumeral joint.⁴ The glenohumeral joint is the most mobile joint in the body.⁵ The AC ligaments provide anterior and posterior stability to the AC joint with the superior component of the ligament providing the greatest stability.⁶ The trapezoid and conoid ligaments make up the coracoclavicular (CC) ligament, which provides vertical stability to the distal clavicle and stabilizes the overall AC joint.⁷ One of the most common shoulder injuries is AC joint separations where a direct impact, such as falling on the shoulder, can potentially lead to AC joint ligament and CC ligament tears with separation and superior displacement of the clavicle from the acromion.⁸ This is classified as a Rockwood type III tear and results in pain with the abduction of the shoulder and an obvious deformity on presentation.⁹

Options for Treatment

Shoulder arthroscopy is the preferred method of treatment over open surgeries for shoulder pathologies that require surgical intervention. Benefits of arthroscopy include smaller incisions, improved visualizations, decreased risk of damage to vascular structures, and faster recovery and rehabilitation.¹⁰ Indications for the shoulder arthroscopy include repair of fractures and ligament tears such as rotator cuff repair, CC ligament repair for AC joint separation, superior labrum anterior and posterior (SLAP) repair, distal clavicle resection, subacromial decompression, and proximal humeral fracture repair.¹¹ Other indications for the shoulder arthroscopy include loose body removal, the release of scar tissue, and severe severe degenerative arthritis, when shoulder arthroplasty is not preferable.^{10, 21}

Rationale for Treatment

The rationale for performing a diagnostic shoulder arthroscopy is to examine and treat shoulder pathologies in a minimally invasive manner. This procedure is particularly useful for the repair of various ligament tears in the shoulder, as well as removing loose bodies, adhesions, and scar tissues. The continued advancement in the safety and efficacy of arthroscopy makes it appealing for both surgeons and patients over open shoulder surgeries.

Discussion

There are two main patient positioning for shoulder arthroscopy: the lateral decubitus position (LDP) and the BCP. The LDP has the patient placed laterally on the table with the surgical arm in a sling with traction applied longitudinally.¹² Traction applied to the surgical arm increases visualization of the glenohumeral joint and subacromial space but leads to higher rates of nerve injuries.¹³ In the BCP, the patient is sitting upright with a 60-degree hip flexion, and the surgical arm is placed on a sterile holder or Mayo stand.¹⁴ Advantages of this upright anatomic position include reduced traction, fewer complications from portal placement, and reduced surgical time.^15,16 The main disadvantage to the BCP is intraoperative hypotension from the reduced cardiac output and mean arterial pressure under general anesthesia; however, this also reduce intraoperative bleeding.¹⁷ Therefore, regional anesthesia is the preferred method of anesthetizing the patient and peripheral nerve blocks can be used to reduce the risk of postoperative complications.¹⁸

After bony landmarks are identified, it is time for portal placement. There are three main portals commonly used in shoulder arthroscopy. Depending on the specific pathology and the need for enhanced visualization and access, additional portals may be employed on a case-by-case basis. The primary portals are: posterior, anterior, and lateral. The secondary portals are: posterolateral, anterosuperior, anteroinferior (5 o'clock), posteroinferior (7 o’clock), anterolateral (port of Wilmington), Neviaser’s portal (Supraspinatus), axillary pouch portal, G-portal (SSN portal), Pec-portal (inferolateral portal).¹²

The posterior portal is the most common portal used and is demonstrated in this video. Entering the soft spot between the humeral head and the glenoid, it is the safest portal to visualize the entire joint.¹² Care must be taken to avoid injuring the axillary nerve and suprascapular nerve.¹⁹ Common procedures performed using this entry point include rotator cuff repair, subacromial decompression, and anterior labral repair.²⁰ Other posterior portals include the posterolateral portal, which is created with an outside-in technique and enters 2-3 cm below the posterolateral edge of the acromion and medial to the subacromial bursa.¹² Similar to the anterolateral portal, entering too inferior risks injury to the axillary nerve.¹⁹ This portal is best as a viewing portal for rotator cuff repairs and labral repairs in the LDP position.²⁰ The 5-o’clock portal is established from the posterior portal to the 5-o’clock position of the glenoid at the inferior glenohumeral ligament.¹⁹ An inside-out technique greatly increases the risk of injury to the axillary nerve, musculocutaneous nerve, cephalic vein, and humeral cartilage.¹² Therefore, this portal is limited and best used for anchor placement in Bankart lesions in the LDP with an outside-in approach.²³ The posteroinferior portal is created with an inside-out approach to enter the 7-o’clock position on the glenoid from the anterior portal.²⁰ The posterior circumflex humeral artery, axillary nerve, and suprascapular nerve are at greatest risk of injury from this portal placement.²⁴ This portal is mainly used for loose body removal and posteroinferior labral fixation.²⁴ The axillary pouch portal is an alternative to the posteroinferior portal that enters the inferior glenohumeral recess with an outside-in approach.²⁵ With the axillary nerve further away, it can be safely used for loose body removal, synovectomy, and anchor placement on the posteroinferior glenoid rim.²⁵

Anterior portals include the anterolateral portal which enters the undersurface of the acromion 2-3 cm distal to the lateral edge.¹⁹ There is a risk of injuring the axillary nerve if the portal is placed too inferiorly. This portal is useful for the treatment of AC joint separation and subacromial impingement.²⁰ The anteroinferior portal is created with an inside-out approach and enters the anterior capsule just superior to the subscapularis tendon, providing better access to the glenoid neck and inferior glenoid.²⁶ The cephalic vein and axillary nerve are at greatest risk of injury with this portal placement.²⁰ This portal is combined with an anterosuperior portal for anterior shoulder capsulorrhaphy.²⁶ The anterosuperior portal uses an outside-in technique to enter between the coracoid and acromion and anterior to the long head of the biceps tendon.¹⁹ The cephalic vein and axillary nerve are at a lower risk of injury compared to the anteroinferior portal.²⁰ In addition to anterior capsule procedures, the anterosuperior portal can be used for anchor placement on the glenoid for superior labral anterior-posterior (SLAP) repair.²⁰

Some special portals used in arthroscopy include the Neviaser portal which enters the soft spot between the clavicle, acromion, and scapular spine, and is used for suture fixation during SLAP repair. The suprascapular nerve and artery are at the greatest risk of injury from this portal.¹² The portal of Wilmington (Anterolateral portal) is also used in SLAP repairs for anchor placement and is created by entering medial to the musculotendinous junction toward the coracoid tip.¹² The axillary nerve is at the greatest risk of injury if placed too inferiorly.²⁰ The suprascapular nerve portal is used for suprascapular nerve decompression and is created with an outside-in approach to enter between the clavicle and scapular spine.²⁷ The suprascapular nerve within the suprascapular notch and the suprascapular artery are at the greatest risk of injury with this portal.²⁰

Postoperative Recovery

Postoperative pain management is one of the most important components of a successful recovery following shoulder arthroscopy. Appropriate pain control allows for early rehabilitation, improves outcomes, and increases patient satisfaction.²⁸ Since there is a wide range of options available for pain management, medications should be individualized for the patient’s needs. Nerve blocks such as interscalene nerve blocks and suprascapular blocks lead to lower pain scores and longer time from surgery to using systemic analgesics such as opioids.²⁹ After adequate pain control, it is imperative for patients to get rehabilitation therapy to improve function and reduce shoulder stiffness. Variations exist in early versus delayed rehabilitation protocols following arthroscopy. Early rehabilitation is thought to benefit patients by improving range of motion and functional scores while delayed rehabilitation is thought to benefit by preventing a reinjury. A systematic review found significantly increased functional scores within the first 3-6 months with early rehabilitation compared to delayed rehabilitation, with no significant increase in reinjury.³⁰ An optimal rehabilitation protocol that attempts to strike a balance between protecting the healing repaired tissue and avoiding re-injury should be established for each patient.

Special Considerations and Contraindications to Shoulder Arthroscopy

Complication rates ranging from 4.6–10.6% have been reported with shoulder arthroscopy.³¹ The most common complications include shoulder stiffness, iatrogenic tendon injury, and vascular injury.³² Therefore, each arthroscopic procedure should be conducted with extreme care to not injure the axillary nerve, musculocutaneous nerve, cephalic vein, and other structures in the surrounding area. Contraindications for shoulder arthroscopy include distorted anatomy that hinders proper portal placement and infection at the site of portals, while special care must be taken when performing arthroscopies on patients with severely increased body mass index.³³ If patients are symptomatic despite nonsurgical treatment with NSAIDs for pain control and rehabilitation with strength and stretching exercises, but contraindications for shoulder arthroscopy present, then depending on the type of pathology open shoulder surgery such as arthroplasty can be explored.