# Shoulder and Knee Arthroscopy: Setup, Portals, and Diagnostic Evaluation

## Introduction

Arthroscopy is a minimally invasive surgical technique that allows direct visualization, diagnosis, and treatment of intra-articular pathology. Shoulder and knee arthroscopy are among the most commonly performed orthopedic procedures. Mastery of patient positioning, portal placement, and systematic diagnostic evaluation forms the foundation for all arthroscopic procedures.

## Shoulder Arthroscopy

### Patient Positioning

The lateral decubitus position places the operative arm in 45 to 70 degrees of abduction and 15 to 20 degrees of forward flexion using a balanced suspension system with 10 to 15 pounds of traction. It offers excellent inferior and posterior access and familiar anatomy for open procedures, though it requires a traction setup and carries risk of brachial plexus neuropraxia. The beach chair position has the patient semi-reclined at 60 to 70 degrees with the arm freely draped. It allows easier setup, the ability to convert to open surgery, and an anatomic orientation similar to the upright patient, but it provides limited inferior access and carries a risk of hypotensive cerebrovascular events.

### Portal Placement

The posterior portal is the primary viewing portal, placed 2 cm inferior and 1 cm medial to the posterolateral acromion corner, entering through the infraspinatus and posterior capsule. The anterior portal is established using an outside-in technique lateral to the coracoid through the rotator interval, or inside-out with a spinal needle. The lateral (subacromial) portal is placed 2 to 3 cm distal to the lateral acromion and serves as the primary working portal for subacromial procedures. The anterosuperolateral (Neviaser) portal passes through the supraspinatus fossa medial to the acromion and is useful for anchor placement in superior labral repairs. The Port of Wilmington is located 1 cm lateral and 1 cm anterior to the posterolateral acromion and is useful for posterior rotator cuff repair. Accessory portals are placed as needed for specific procedures under direct visualization.

### Systematic Diagnostic Evaluation

A 15-point diagnostic arthroscopy of the shoulder evaluates: the biceps tendon (long head) and its anchor; the superior labrum (SLAP region); the anterior labrum and glenohumeral ligaments (SGHL, MGHL, IGHL); the inferior labrum and axillary recess; the posterior labrum; articular cartilage of the glenoid; articular cartilage of the humeral head (noting that a bare area is normal); the rotator interval and coracohumeral ligament; the subscapularis tendon (intra-articular portion); the supraspinatus and infraspinatus (drive-through assessment); the posterior capsule and recess; the subacromial bursa (a separate compartment); the undersurface of the acromion and coracoacromial ligament; the acromioclavicular joint (from below); and the rotator cuff bursal surface.

## Knee Arthroscopy

### Patient Positioning

The patient is positioned supine with the operative leg hanging off the side of the table at the knee break. A lateral post at the proximal thigh provides valgus stress for medial compartment access, or alternatively a leg holder may be used. A tourniquet is applied to the proximal thigh (optional, inflated to 250 to 300 mmHg if used). The knee must allow full range of motion from full extension to greater than 90 degrees of flexion.

### Portal Placement

The anterolateral portal is the primary viewing portal, placed 1 cm lateral to the patellar tendon at the level of the inferior pole of the patella with the knee at 90 degrees of flexion. The anteromedial portal is the primary working portal, placed 1 cm medial to the patellar tendon and established under direct visualization using a spinal needle for localization. The superolateral portal above the patella is used for inflow or drainage. The posteromedial portal is established under direct visualization with transillumination and is used for posterior horn meniscal work or loose body removal. The posterolateral portal is established similarly for posterior compartment access. Accessory portals include the transpatellar tendon portal (central) and far medial or lateral portals as needed.

### Systematic Diagnostic Evaluation

A systematic 8-point diagnostic arthroscopy of the knee evaluates: the suprapatellar pouch (synovium, plica, loose bodies); the patellofemoral joint (patellar and trochlear articular cartilage, patellar tracking); the medial gutter (medial synovial plica, medial capsule, loose bodies); the medial compartment (medial femoral condyle cartilage, medial tibial plateau cartilage, medial meniscus probed on all surfaces); the intercondylar notch (ACL, PCL, ligamentum mucosum or fat pad); the lateral compartment (lateral femoral condyle, lateral tibial plateau, lateral meniscus including the popliteal hiatus); the lateral gutter (lateral capsule, loose bodies); and the posterior compartment when indicated (posterior capsule, posterior loose bodies).

## Technical Considerations

Pump pressure should be maintained at 40 to 60 mmHg for the knee and 50 to 60 mmHg for the shoulder to balance visualization with fluid extravasation. A 30-degree arthroscope is the standard for both shoulder and knee. A 70-degree scope is useful for posterior compartment visualization in the knee and posterior glenoid assessment in the shoulder. Portals should always be established under direct visualization when possible to avoid iatrogenic damage. Fluid management requires monitoring for excessive fluid extravasation, particularly in shoulder arthroscopy, where there is a risk of airway compromise.

## Complications

Neurovascular injury is a key concern: the axillary nerve is at risk with inferior shoulder portals, the saphenous nerve and its infrapatellar branch with medial knee portals, and the peroneal nerve with lateral knee portals. Other complications include instrument breakage and retained loose bodies, fluid extravasation and compartment syndrome (rare), infection (less than 0.5%), thromboembolic events, and chondral scuffing from portal placement or instrument use.

## Clinical Pearls

The posterior portal is the primary viewing portal for shoulder arthroscopy, while the anterolateral portal is the primary viewing portal for knee arthroscopy. A systematic diagnostic evaluation must be performed before any therapeutic intervention. Portal placement accuracy is critical and should use anatomic landmarks and spinal needles for localization. The 30-degree arthroscope is the standard, with a 70-degree scope always kept available. Fluid pressure and flow must be monitored carefully to avoid extravasation complications.

## References
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3. Ahn JH, Oh I. "Arthroscopic All-Inside Lateral Meniscus Repair: Technical Tip and Outcome." *Arthroscopy Techniques*. 2016;5(5):e1055-e1059.
4. Randelli PS, Cucchi D, Butt U, et al. "History of Shoulder Arthroscopy." *Knee Surgery, Sports Traumatology, Arthroscopy*. 2021;29(7):2085-2091.