Page 48 - ISAKOS 2020 Newsletter Volume 2

CURRENT CONCEPTS
Difficult Elbow Problems: Heterotopic Ossification and Calcification
Skin Incision
Single or multiple skin incisions can be used; the choice depends on the location and extent of the HO. A precise preoperative plan based on radiographs and CT scans helps to define the best approach.
Medial and lateral exposure can be performed through two single incisions or a single posterior skin incision (known as the “global” approach to the elbow). A midline posterior incision is typically straight, passing few centimeters medial or lateral to the tip of the olecranon. Then, two full-thickness fasciocutaneous flaps are elevated from the skin to the fascia of the triceps, preserving the blood supply and reducing the risk of cutaneous neuroma. The ulnar nerve is identified proximally, and neurolysis or subcutaneous anteposition are advised, depending on the clinical symptoms and the location of the HO.
Lateral Exposure
The “column procedure” for simple release of extra-articular elbow contracture, described by Morrey, can be useful for HO excision as it allows for exposure of both the posterior and anterior compartments of the elbow joint5. Exposure and release of the anterior compartment can be performed by elevating the brachioradialis and extensor carpi radialis longus muscles from the anterior aspect of the lateral epicondyle. The posterior compartment is exposed, and the triceps is released and elevated from the posterior humeral surface.
Medial Exposure
The medial approach begins with exposure of the posterior joint capsule and olecranon fossa from the medial side following exposure of the ulnar nerve. The medial border of the triceps is elevated from the intermuscular septum and the medial epicondyle. The anteromedial release is performed though the internervous plane between the flexor carpi ulnaris (innervated by the ulnar nerve) and the flexor-pronator muscle (innervated by the median nerve). The common flexor-pronator origin can be elevated to improve exposure of anteromedial joint compartment.
Posterior Exposure
In cases of extensive posterior HO, a useful exposure to the distal part of the humerus is the bilaterotricipital or paratricipital approach described by Alonso-Llames, which involves the lateral and medial edges of the triceps. Another approach involves splitting the triceps tendon, preserving the medial olecranon insertion (proper tendon), and divaricating the muscle-tendon unit to expose the posterior compartment.
Proximal Radioulnar Synostosis
The anconeus and extensor carpi ulnaris complex are elevated from the ulna, with their origins from the lateral epicondyle being left intact. Alternatively, the Kocher approach can be used, thus creating an interval distal to the lateral epicondyle between the anconeus and the extensor carpi ulnaris. The subperiosteal dissection is carried along the proximal part of the ulna toward the anterolateral surface of the radius and to the base of the synostosis. If dissection continues distally, the release of the two heads of the supinator muscle from the ulna allows to improve the distance between the synostosis and the posterior interosseous nerve moving it medially inside the supinator muscle.
Arthroscopic Technique
Arthroscopic early excision (<6 weeks after the development of HO) has been suggested by some authors. Both anterior and posterior extensive ossifications can be easily removed during this early phase with a soft-tissue shaver because of the tenderness of metaplastic bone.
The procedure can be performed with the patient in the prone, supine, or lateral decubitus position. Distention of the joint with saline solution through the soft spot may not be an effective solution because of capsular retraction, but it is helpful to shift the anterior neurovascular structures away before introducing the trocar. The ulnar nerve has to be localized and, once a proximal anteromedial portal is established to visualize the anterior joint capsule, the proximal anterolateral portal is created with use of the outside-in technique. Anteriorly, the HO is usually located anterior to the capsule and posterior to the brachialis.
The first step is to assess the anterior compartment by performing the release of the anterior capsule from the humerus and then resecting the capsule until the HO is exposed. It is useful to establish a straight lateral portal with a switching stick (such as a retractor), which can be used to retract the brachialis away from the HO and protect the anterior neurovascular structures. Next, the HO is resected from top to bottom, with the shaver always staying posterior to the switching stick and brachialis muscle. Switching the arthroscope and the shaver can be useful for the removal of any remaining HO. In some cases, because of the presence of a thick capsule, anterior capsulectomy may be required. The capsulectomy is performed by trimming the proximal humeral capsule with the shaver and then using a basket forceps to complete the maneuver. It is useful to start about 1 cm proximal to the apex of the coronoid, first proceeding from lateral to medial and then proceeding in the opposite direction.
46 ISAKOS NEWSLETTER 2020: VOLUME II