Introduction
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The modern era of management of shoulder pathology began in the 1930s with the work of Codman.
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Significant contributions to understanding of rotator cuff pathology originated with Neer, whereas Bankart and Rowe were the major proponents of concepts underlying the current understanding of shoulder instability.
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The management of shoulder arthritis in the modern era is credited to Neer.
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Arthroscopy of the shoulder did not become routine practice until the 1980s.
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Since that time, developments in technology have led to routine use of arthroscopy for diagnosis and treatment of several different pathologic conditions of the shoulder.
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Ongoing technologic advances ensure that shoulder arthroscopy will continue to evolve as a treatment modality for shoulder disorders.
Preoperative Considerations
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Review all pertinent medical records and perform a thorough history and physical examination prior to the procedure and obtain appropriate imaging to confirm the diagnosis and to reduce the risk of surprises.
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Preoperative consultation with appropriate primary care or medical specialists and anesthesiologists to decrease perioperative risk of complications
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Anesthesia can consist of general, general with regional nerve blocks, or regional anesthesia alone.
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General anesthesia is usually chosen in combination with a regional nerve block for patient comfort during and after the procedure.
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Regional nerve blocks give longer pain relief postoperatively. Regional anesthesia alone, however, usually is poorly tolerated when the procedure is performed in the lateral decubitus position.
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Hypotensive anesthesia aids in visualization during the procedure and reduces blood loss.
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Examination under anesthesia (EUA)
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Should be performed on every patient prior to beginning the procedure
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Systematic examination should be performed including evaluation of range of motion (ROM) and stability of the shoulder.
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Positioning
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Lateral decubitus ( Fig. 5-1 )
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In the supine position, the patient undergoes general anesthesia and an examination under anesthesia is performed.
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The patient is placed in the lateral decubitus position using a bean bag, often rotated backward 20 degrees. An axillary roll is used to protect the brachial plexus and padding is placed between the down leg and table, as well as between the knees, as all bony prominences must be well padded.
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Most arthroscopists will place the arm in a sterile traction device with the arm in 45 to 70 degrees of abduction and 20 to 30 degrees of forward flexion. A 10 to 15 lbs of traction is usually adequate.
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All arthroscopic shoulder procedures can be performed from this position, with posterior shoulder stabilization a little easier in the lateral decubitus position.
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Higher risk of neuropraxia has been documented as a result of traction.
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Conversion to an open procedure may require repositioning and redraping the patient.
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Regional anesthesia by itself is often not well tolerated in this position.
Figure 5-1
The lateral decubitus position for shoulder arthroscopy.
(Courtesy of Arthrex, Naples, Florida.)
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Beach chair ( Fig. 5-2 )
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Patient is placed supine and an examination under anesthesia is performed in this position.
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The patient is then placed in a beach chair position as seen in Figure 5-2 .
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Be careful to monitor the blood pressure while the patient is being brought up into the beach chair position.
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Be careful of the neck position and head support when positioning the patient
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Protect the elbow/ulnar nerve of both arms as they may have pressure depending on how they are held during the arthroscopy.
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Easier for anesthesia control during surgery
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Position makes conversion to open procedure easier.
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General anesthesia with regional nerve blocks or regional alone can be tolerated.
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Risk of cerebral hypoperfusion with hypotensive anesthesia as well as the small risk of air embolism
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Difficulty performing posterior stabilization
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Easier to perform dynamic assessment (no traction to remove from the arm)
Figure 5-2
Beach chair positioning for shoulder arthroscopy.
(From Miller MD, Cole BJ. Textbook of Arthroscopy. Philadelphia, Elsevier, 2004 [Fig. 8-2B, p 67].)
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Equipment
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Arthroscope
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30-degree arthroscope most commonly used
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70-degree arthroscope useful for access to anterior labrum/glenoid, inferior glenohumeral ligament and sub-coracoid region.
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Cannulas
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Decrease fluid extravasation into the surrounding soft tissue
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Maintain portal position without the need to create new portal sites and thus create undue soft tissue trauma
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Necessary for arthroscopic knot-tying to reduce the risk of capturing unwanted soft tissue in the knot
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Instruments
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Full complement of shoulder instruments has been devised to aid in the performing of procedures for manipulation and/or repair of soft tissues
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Arthroscopic soft tissue graspers
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Arthroscopic curettes
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Arthroscopic biters
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Arthroscopic rasps
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Arthroscopic microfracture awls
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Arthroscopic soft tissue–penetrating, suture-passing or grasping devices
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Arthroscopic suture-passing devices
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Arthroscopic suture-management cannulas
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Arthroscopic shavers
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Arthroscopic burrs
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Underwater Bovie or radiofrequency devices aid with visualization during the procedure by allowing coagulation or soft tissue ablation.
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Arthroscopic suture anchors
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Arthroscopic tacks
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Relevant Anatomy ( Fig. 5-3 )
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Glenohumeral joint
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Greatest range of motion of any joint at the expense of stability
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Static restraints are the bony anatomy, glenoid labrum, ligaments, and capsule. The dynamic restraints are the muscles about the shoulder, the negative-pressure system, and adhesion-cohesion.
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Rotator interval (RI)
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Area of the capsule between the subscapularis inferiorly and the supraspinatus superiorly
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The coracoid forms the medial base and the transverse humeral ligament forms the lateral apex.
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The contents of the RI are the biceps tendon, coracohumeral ligament (CHL) and superior glenohumeral ligament (SGHL)
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Labrum
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Deepens the joint
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Increases the surface area
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Anchors glenohumeral ligament complex
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Varying anatomy and shapes
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Anterosuperior labrum may not be attached, and this normal variant is known as a sublabral foramen.
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Glenoid
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Pear shaped with average of 5 degrees of upward tilt and between 7 degrees of retroversion to 10 degrees of anteversion
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There is a bare area in the middle of the glenoid, halfway between the anterior and posterior borders of the glenoid.
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Ligaments
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Thickenings in the capsule.
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Superior glenohumeral ligament (SGHL)
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The SGHL and coraco-humeral ligament (CHL) resist inferior translation and external rotation with the arm in adduction. They also resist posterior translation with the arm flexed forward, adducted, and internally rotated.
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Superior glenohumeral ligament has two sites of origin: the coracoid and the supraglenoid tubercle—just anterior to the long head of biceps origin on the superior labrum. Its insertion is on the proximal lesser tuberosity.
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Origin of the CHL is extra-articular on the lateral surface of coracoid. The CHL insertion is the greater and lesser tuberosities spanning the bicipital groove.
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Middle glenohumeral ligament (MGHL)
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Most variable anatomy
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Absent in as many as 30% of patients
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Resists external rotation when the arm is abducted and anterior/posterior translation of the arm at 45 degrees of abduction and external rotation
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Origin is the anatomic of the proximal humerus neck and insertion is the labrum.
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Inferior glenohumeral ligament (IGHL)
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The PRIMARY RESTRAINT to anterior, posterior, and interior translation of the joint with the arm elevated 45 to 90 degrees
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Origin is anterior inferior labrum
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Anterior band limits anterior translation in external rotation and abduction.
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The posterior band limits posterior humeral head translation in abduction and internal rotation
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The area between the anterior and posterior bands, known as the axillary pouch, may function as a hammock, holding the humeral head.
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Dynamic restraints are the biceps tendon, rotator cuff, and surrounding musculature.
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Rotator cuff muscle acts to depress and compress the convex humeral head against the concave glenoid.
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Subscapularis inserts on the lesser tuberosity.
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Supraspinatus, infraspinatus, and teres minor insert on the greater tuberosity.
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Internal rotators of the shoulder are the pectoralis major, latissimus dorsi, and subscapularis.
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External rotators are the teres minor and infraspinatus.
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The biceps tendon is located in the Rotator Interval as described earlier and its function in stabilization is still debated.
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The biceps is the lighthouse of the arthroscopic anatomy of the shoulder.
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The biceps inserts into the superior labrum.
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The supraspinatus tendon inserts on the articular margin of the greater tuberosity over a distance of 12 to 18 mm.
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The bare area is the area of the posterosuperior humeral head just posterior to the supraspinatus insertion where the rotator cuff does not attach to the articular margin and there is exposed bone and no articular cartilage.
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Acromioclavicular joint
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Gliding joint with fibrocartilaginous disc.
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Acromioclavicular (AC) ligament prevents anteroposterior translation of the distal clavicle.
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Coracoclavicular (conoid and trapezoid) ligament prevents superior displacement of the distal clavicle (actually the clavicle and coracoclavicular ligaments prevent drooping of the scapula [acromion]).
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The AC joint does contribute to shoulder motion.
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