Diagnosis is often made on the basis of history, examination and investigations. However, diagnostic shoulder arthroscopy remains a useful tool in the armament of the orthopaedic surgeon as some pathologies remain difficult to diagnose with standard non-invasive investigations.
Diagnostic arthroscopy therefore offers the opportunity to establish or confirm a diagnosis
with the possibility to proceed to treatment with the appropriate consent.
Diagnostic arthroscopy is most frequently used for:
• Undiagnosed shoulder pain
• Complex instability, including humeral avul-sion of the glenohumeral ligaments (HAGL) lesions
• Small/partial thickness rotator cuff tears.
Contraindications
• Infection of overlying skin
• Lack of proper arthroscopic instrumentation
• Gross osteoarthritis is a relative contra -indication.
Consent and risks
• Nerve injury: the musculocutaneous nerve (anterior portal) and the axillary nerve (lateral portal) are most at risk. The suprascapular nerve can be damaged by the inexperienced
arthroscopist
• Chondral or labral injuries: relatively uncommon
• Fluid imbalance due to fluid extravasation
• Infection: very rare
• Vascular injury: very rare Position of arthrodesis
• Internal rotation 30°
• Flexion 30°
• Abduction 30°
Shoulder Range of motion
External rotation 80°
Internal rotation 90°
Flexion 180°
Abduction 180°
Operative planning
Recent radiographs and when relevant, ultra -sound, computed tomography (CT) and magnetic resonance (MR) images (± arthrograms), should be available. Although only basic equipment is necessary for a diagnostic procedure standard equipment should be available so that therapeutic treatment can be undertaken if necessary. This includes:
• Camera with imaging and recording equipment
• Xenon light source
• Fluid management system (pump set at 30–70 mmHg)
• 5 mm 30° scope with high-flow sleeve
• Shaver
• Vaporizer
• Arthroscopic instruments
• Cannulas
• Arthroscopic implants.
Anaesthesia and positioning
General anaesthesia is preferred with the use of an interscalene block if certain procedures are planned. The choice of patient positioning is very much surgeon dependent:
• If the lateral position is used, the patient should be as far back towards the edge of the table as possible, with 15° of posterior tilt (horizontal glenoid). Front and back supports are required to secure the patient. The patient’s head is placed in a gel ring. Four kilograms of longitudinal skin traction is applied with the arm in 30–50° abduction and 20–30° forward flexion (Fig. 6.1). The brachial plexus should be palpated to ensure that it remains soft and that excessive traction is not being applied
• If the beach chair position is used, the appropriate operating table (with removable lateral corner) is required. The patient’s head is appropriately secured. Traction can be added based on surgeon preference. This approach is helpful if progressing to an open procedure.
The surgical field is prepared with a germicidal solution and waterproof drapes are used with adhesive edges to provide a seal to the skin.
SURGICAL TECHNIQUE Landmarks
• Spine of the scapula
• Posterolateral corner of the acromion, lateral acromion, and anterolateral corner of acromion
• Distal clavicle and acromioclavicular joint (ACJ)
• Tip of the coracoid.
Portals
The accurate placement of arthroscopic portals is essential in shoulder arthroscopy. A variety of portals can be used. The commonest viewing portal is the posterior portal. A stab incision to the skin is placed 2 cm medial and 2 cm inferior to the posterolateral corner of the acromion. This correlates to a palpable soft spot which denotes the plane between the infraspinatus and teres minor.
To access the glenohumeral joint, the scope is aimed inferomedially towards the tip of the coracoid. The glenoid rim and the humeral head can be palpated and the scope can be pushed between them. A popping sensation is usually felt Traction
Figure 6.1 Positioning and traction for shoulder arthroscopy
as the joint is entered. Once the posterior portal is established all other portals are made using an outside-in technique in which a spinal needle is used to determine the exact location and angle of entry into the joint.
A standard low anterior portal can also be used for passing instruments into the joint. It is placed above the lateral half of the subscapularis but medial to the medial biceps pulley. Once the needle has been placed in the appropriate position the portal is made using a size 11 scalpel, which is inserted in the same direction as the needle taking care to avoid the long head of the biceps (LHB).
To enter the subacromial space, the same posterior portal skin incision is used; however, the scope is aimed superolaterally towards the anterolateral corner of the acromion. The scope
must enter the bursa and show the acromion and the bursal aspect of the cuff clearly. If cobweb-like tissue is seen, then the scope is outside the bursa and should be repositioned. This is important as the bursa helps to contain the irrigation fluid, thus limiting soft tissue swelling around the shoulder.
The lateral portal is 5 cm (three fingers breadth) distal to the acromion and 1 cm anterior to the mid-lateral line (in line with the posterior line of the ACJ). This portal is used for instrumentation of the subacromial space (Fig. 6.2).
Other portals can be made on demand. These include the anterosuperolateral, accessory anterior, accessory lateral, accessory posterior and Neviaser (superior) portals. A cannula may be used if proceeding to a therapeutic procedure.
Clear cannulas are recommended as they allow visualization and aid in suture management.
Procedure
With the scope in the posterior portal, the glenohumeral joint is assessed first. By using the LHB tendon as a reference, the camera is adjusted so that the image is shown in the correct supero -inferior plane. The authors recommend the following systematic way of assessing the shoulder:
• The LHB should first be assessed at its insertion at the superior glenoid tubercle. By raising the arm in 90° abduction and 90° external rotation, the presence of a SLAP (superior labrum from anterior to posterior) tear can be assessed as the labrum rolls off the glenoid rim (peel-back sign). The scope can then be turned laterally and the intra-articular portion of the LHB, and that portion of the biceps tendon that lies within the inter-tubercular grove, can be assessed.
• The stability of the LHB can then be visualized by internally and externally rotating the shoulder. The medial sling/pulley can then be inspected before examining the subscapularis tendon, superior glenohumeral ligament and rotator interval in more detail. The sub scapu laris A systematic approach is essential if pathology is not to be missed.
Diagnostic shoulder arthroscopy 61
Lateral portal
Posterior portal Anterior
portal
2 cm 2 cm
Figure 6.2Common arthroscopic portals
tendon insertion can be best visualized with the arm in internal rotation.
• By gently withdrawing the scope and looking laterally, the posterior pulley of the LHB can be viewed and then the supraspinatus and infraspinatus tendons can be examined. The bare area and any Hill–Sachs lesions can now be identified.
• As the arthroscope is taken further inferiorly it enters the inferior recess. The reflection of the inferior capsule and the posterior band of the inferior glenohumeral ligament (hammock effect) can be seen. By then rotating the scope, the posterior inferior labrum can be visualized and then the entire posterior and superior labrum examined before assessing the chondral surfaces of both the humeral head and glenoid.
• The anterior stabilizing structures can now be examined. Superiorly the sublabral foramen, labrum and the middle glenohumeral and anterior band of the inferior glenohumeral ligaments can all be visualized.
• An anterior portal can be made through the rotator interval for the introduction of a probe for further assessment of any soft tissue pathology or if any glenoid bone loss needs to be further assessed.
• The subacromial space should then be examined. Superiorly the acromion is seen, anteriorly the coracoacromial ligament and inferiorly the bursal side of the rotator cuff. The presence of bursal side rotator cuff tears, impingement lesions and acromial and ACJ pathology can all be assessed.
This is just one example of a systematic assess -ment of arthroscopic shoulder anatomy. Each surgeon can develop their own system, however, it is essential that all surgeons are familiar with arthroscopic anatomy and normal variations.
Closure
Portals can be left unsutured or closed with subcuticular 3/0 Monocryl sutures.
POSTOPERATIVE CARE AND INSTRUCTIONS
If the procedure is purely diagnostic no sling is necessary. The patient is encouraged to mobilize as soon as possible.
RECOMMENDED REFERENCE
Levy O, Sforza G, Dodenhoff R, et al.Evaluation of the impingement lesion: pathoanatomy and classification. Arthroscopic evaluation of the impingement lesion: pathoanatomy and classifica -tion. J Bone Joint Surg Br 2000;82B(Suppl 3):233.