Elbow Arthroscopy and Related Anatomy

Fig. 25.1

Relevant elbow anatomy. (a) Lateral view of the elbow. (b) Medial view of the elbow

Superficially, the nerves that one must be aware of are the medial and lateral antebrachial cutaneous nerves. The medial antebrachial cutaneous nerve (MABC) originates off the medial cord of the brachial plexus and travels along the ulnar aspect of the arm, along with the basilic vein. It pierces the deep fascia at the middle of the arm, where it branches and provides sensation to the ulnar aspect of the forearm. The lateral antebrachial cutaneous nerve is the termination branch or continuation of the musculocutaneous nerve. Proximal to the antecubital fossa, it emerges from the distal aspect of the biceps brachii and courses lateral along the brachioradialis. It then divides into volar and dorsal branches, supplying sensation to the radial forearm.

The deep neurovascular structures along the elbow include the median, radial, and ulnar nerves and the brachial artery. The brachial artery can be found proximally between the brachialis and biceps brachii. It courses medial to the biceps tendon and branches at the level of the radial head. The median nerve travels with the brachial artery on its medial side. It crosses the joint and enters the forearm deep to the pronator teres. Proximally, the ulnar nerve courses posterior to the intermuscular septum. It continues to travel posterior to the medial epicondyle at the elbow joint and enters the forearm between the flexor digitorum superficialis and profundus. The radial nerve pierces the lateral intermuscular septum approximately 7.5 cm proximal to the joint line. It then courses through the anterior compartment between the brachialis and brachioradialis. At the elbow joint, the radial nerve bifurcates into the superficial sensory branch and the deeper posterior interosseous nerve. The superficial branch enters the forearm deep to the brachioradialis, while the posterior interosseous nerve pierces the supinator muscle and curves around the radial head.

25.3 Clinical Presentation and Physical Examination

25.3.1 Patient History

A comprehensive history is important in the formation of a differential diagnosis of the elbow. Mechanism of injury, signs, and symptoms should be elicited to determine whether this is acute in nature or chronic from repetitive trauma. Other important information to aid in the decision-making includes: patient age, hand dominance, activity level, and occupation.

Understanding the location of injury can also help narrow the differential diagnosis [7]. Pain along the medial aspect of the elbow carries a wide differential including: cubital tunnel syndrome, ulnar neuritis, ulnar nerve subluxation, ulnar collateral ligament (UCL) injury, and medial epicondylitis. Symptoms in the lateral region of the elbow can be due to: lateral epicondylitis, radial head fracture, osteochondritis dissecans (OCD) lesions, and lateral collateral ligament injury following a simple dislocation. The differential diagnosis for symptoms at the anterior elbow in includes: distal biceps rupture and anterior capsular strain. Posterior elbow pain can result from olecranon bursitis or fracture, triceps tendon pathology, loose bodies, and valgus overload extension.

25.3.2 Physical Examination

As with all upper extremity evaluations, a thorough cervical spine examination should be performed first. Findings of radiculopathy and myelopathy should warrant further workup, including cervical spine imaging. It is also important to examine the ipsilateral shoulder and contralateral elbow.

The physical examination of the elbow is no different from any other examination of a joint: inspection, palpation, range of motion, and joint-specific special testing. Upon inspection, one should first look for swelling or fullness of the joint. Depending on the location, the differential can include: radial head or olecranon fracture, olecranon bursitis, triceps avulsion, synovitis, ulnar collateral ligament injury or avulsion, and distal biceps rupture. Erythema of the joint should prompt the physician to be wary of an infectious or inflammatory process.

Although the location of the patient’s symptoms may lead the physician to focus on the afflicted area, it is important to palpate all four regions of the elbow. This helps ensure that coexistent injury or pathology will not be missed.

Range of motion is evaluated in two planes: flexion and extensions and pronation and supination. Active and passive range of motion should be recorded accurately. Morrey et al. [8] evaluated 33 normal patients and the amount of elbow motion needed to carry out activities of daily living. Most activities can be accomplished with 100° of elbow flexion (30–130°) and 100° of forearm rotation (50° of pronation to 50° of supination). Range of motion outside of these parameters can indicate a significant functional disability.

Specific testing of the elbow generally revolves around assessing stability. The two most common forms of instability are valgus instability and posterolateral rotatory instability (PLRI). Valgus instability is generally seen following ulnar collateral ligament insufficiency, in particular the anterior bundle [9]. The moving valgus stress test as described by O’Driscoll et al. [10] is commonly used to assess valgus stability. This is performed by having the examiner apply and maintain a valgus load to the flexed elbow and then quickly extending it. The test is considered positive if this reproduces the patients medial elbow pain and is generally seen between 70° and 120° of flexion.

Posterolateral rotatory instability can be assessed by the lateral pivot-shift test. With the patient supine and affected extremity over head, the forearm is supinated, and valgus to varus stress is applied while the elbow is flexed. A positive test is defined by reproduction of symptoms, signs of apprehension, or subluxation.

25.4 Essential Radiology

Three views (anteroposterior, lateral, and oblique) of the elbow are evaluated. These are useful in identifying fractures, loose bodies, osteophytes, and osteochondral lesions.

Advanced imaging studies such as MRI are useful to evaluate soft tissue structures about the elbow. In particular, the collateral ligaments and chondral injuries can be closely scrutinized. Non-displaced fractures and common extensor tendons tears can also be assessed. Arthrography can be a useful adjunct in diagnosing collateral ligament injuries.

25.5 Indications and Contraindications

Classic indications for elbow arthroscopy included diagnostic arthroscopy and removal of loose bodies. As instrumentation and techniques continue to evolve, indications for elbow arthroscopy have expanded to: capsular release, synovectomy, lateral epicondylitis, treatment of OCD lesions of the capitellum, and certain intra-articular fractures.

The primary contraindication for elbow arthroscopy is any change in the patient’s normal anatomy in whom arthroscopy carries a high risk of neurovascular injury [11]. Other contraindications include prior ulnar nerve transposition and erythema or soft tissue infection around the elbow.

25.6 Surgical Considerations

25.6.1 Anesthesia

Either general or regional anesthesia may be used for elbow arthroscopy. The advantages of general anesthesia include various options for patient positioning and total muscle relaxation. Disadvantages include the potential for greater postoperative pain and a longer post anesthesia recovery.

Regional anesthesia, with or without intravenous sedation, includes interscalene block and axillary block. The advantage of regional anesthesia is that it optimizes postoperative pain control, minimizes postoperative nausea, and facilitates positioning of the patient. The main disadvantage of regional anesthesia is the inability to perform a postoperative neurologic examination to determine whether nerve injury has occurred. At our institution, we typically use general anesthesia and reserve a regional block postoperatively, once the patient completes a full neurologic exam.

25.6.2 Instrumentation

The arthroscopic systems used in the larger joints (4.0-mm, 30° offset arthroscope) allow good visualization of the elbow. The smaller 2.7-mm arthroscope is typically not employed but may be useful to visualize smaller spaces such as the lateral compartment from the direct lateral portal. It is important to use elbow cannula systems that are compatible with both the 4.0- and 2.7-mm arthroscopes to enable switching between viewing and working portals without repeated injury to the elbow capsule and risk to the neurovascular structures. Non-vented cannulas should be used in order to decrease fluid extravasation into soft tissue, and trocars should be conical and blunt tipped in order to decrease the risk of neurovascular injury.

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