Tips for Basic Shoulder Arthroscopy Part 2- Diagnostic routine
My name is Gavin Jennings. I’m a shoulder surgeon in Bath, UK.
This second part of a series on getting started in shoulder arthroscopy is concerned with the diagnostic routine. This outlines the importance of having a system of assessing all the structures in the joint and subacromial space to ensure that no pathology is missed.
In order to get into and work within the shoulder joint safely it is important to be able to determine the sites of certain parts of the surface anatomy around the shoulder girdle.
Important landmarks include the posterolateral corner of the acromion as a reference for siting the initial portal,
the ACJ for working within the joint itself, but also to help site an anterior working portal,
and the coracoid to avoid risk of damage to the neuromuscular structures medial to it.
The standard posterior portal is made 1 to 2 cm inferior and medial to the posterolateral corner of the acromion, aiming the scope towards the tip of the coracoid anteriorly.
The ACJ, if not easily palpable can be found anterior to the soft spot where the scapular spine converges with the clavicle. The anterior portal is made about 1 cm inferior to the joint, with the direction of entry surprisingly vertical. A spinal needle is used to enter the joint at the correct point under direct vision.
These pictures clearly show why it is sensible to avoid making portals medial to the coracoid!
The remainder of the talk refers to arthroscopy in the beach chair position, but the principles are the same for lateral decubitus.
When starting out with shoulder arthroscopy it can be very helpful to mark the surface position of the structures mentioned above ie the acromion, scapular spine, ACJ and coracoid.
Many surgeons like to infiltrate the estimated sites and tracks of the portals with 1:200,000 Adrenaline and also mix Adrenaline into the inflow N-Saline fluid.
Shoulder arthroscopy requires frequent use of the thirty degree offset of the scope to aid visualisation. The analogy I use for teaching is that if you go into a dark room, you shine your torch at the areas you want to see better. Likewise in shoulder arthroscopy, you should shine the light lead (and hence the camera offset) to look at the structures you are assessing.
Once inside the shoulder we need to be aware of the normal and patho-anatomy of the glenohumeral joint and subacromial space. Normal variants and patho-anatomy are not covered in this talk.
The various segments of the glenohumeral joint are conventionally described as per a clock face for the right shoulder or as a mirror image of a clock for the left shoulder.
The first structure to identify and assess should always be the long head of the biceps tendon. After that the diagnostic routine should proceed systematically and consistently to ensure that no structures are inadvertently neglected. The order of the routine is not important, it is having a reproducible routine that is critical.
The biceps can be followed until it exits the joint. At this point the biceps sling and upper border of the subscapularis can be assessed. Internal rotation of the arm will improve visualisation at this site.
The middle glenohumeral ligament crosses the subscapulararis at an angle of about 45 degrees
The undersurface of the rotator cuff is then assessed. Taking the arm into the abducted / externally rotated position allows better assessment of the rotator cuff insertion. The supraspinatus is seen anteriorly and as the scope is moved posteriorly, the undersurface of the infraspinatus will be seen. There is often a significant “bare area” of articular cartilage at the junction of the cuff muscles and this should not be confused with a Hill-Sachs lesion.
The scope is then aimed inferiorly and the axillary pouch is then visualised.
Next the scope is moved back between the joint surfaces to assess the articular cartilage and anterior and superior labrum. The posterior labrum can usually only be fully assessed by viewing backwards through an anterior portal.
The inferior most part of the labrum at the six o’clock position is only easily seen in fairly lax joints.
The scope is then removed from the GH joint and is directed superiorly aiming at the anterolateral corner of the acromion. If the bursa is entered correctly, a clear enclosed cavity will be seen.
The coracoacromial ligament is the first structure to look for. This actually crosses under and on the lateral side of of the anterolateral corner of the acromion.
The amount of subacromial space, the bursa and rotator cuff are then assessed and if there are any concerns about damage to the cuff, a probe or trochar may be introduced through a lateral portal to feel for any thinning or tears.
Many thanks for listening to Part 2 of the series on Basic Shoulder Arthroscopy.
If you require any further information please do not hesitate to contact me. More educational content can be found on the website shoulderspecialists.co.uk