ANATOMY AND BIOMECHANICS

The radial head is an important stabilizer of the elbow. A number of biomechanical studies have investigated the effect of radial head resection on the kinematics and stability of the elbow. The radial head is particularly important as a stabilizer in the setting of valgus instability due to medial collateral ligament insufficiency.⁶^–⁹ It is also important in tensioning the lateral collateral ligament,⁷ and posterolateral rotatory instability has been reported after radial head excision in vitro⁷^,¹⁰ and clinically.¹¹^,¹² The role of the radial head in axial stability of the forearm is evident by the common finding of proximal migration of the radius after radial head resection.¹³^–¹⁷

Radial head excision results in increased loading of the remaining ulnohumeral articulation. This effect is caused by the altered elbow kinematics and the fact that the loads originally borne by the radiocapitellar articulation must be accepted by the ulnohumeral joint.⁸ Although this increased ulnohumeral load has not been studied biomechanically, it is thought to explain the high incidence of ulnohumeral osteoarthritis reported in patients after acute radial head resection for radial head fractures.¹⁴^–¹⁷ Extensive biomechanical evidence supports the beneficial stabilizing effects of prosthetic replacement of the radial head.⁷^–⁹^,^18,¹⁹ These findings suggest that, whenever possible, the radial head should be replaced after it is resected, particularly in cases of acute trauma, in which occult ligament injuries are common.

PATIENT EVALUATION

History and Physical Examination

Several considerations are important in deciding whether to perform an arthroscopic radial head resection. The assessment starts with a thorough history. Pain and stiffness are common complaints related to the radiocapitellar deformity, both of which may be more pronounced with pronosupination rather than flexion and extension. Mechanical symptoms, including clicking, catching, or locking, may be prominent. The examiner should elicit a history surrounding any underlying disease process (e.g., inflammatory arthritis, primary osteoarthritis, hemophilia) and prior treatment. A history of trauma and surgical procedures is important. Obtaining previous operative reports and imaging can be helpful.

A detailed physical examination should be performed. The carrying angle and bony contours of the elbow should be observed. Prior traumatic and surgical incisions should be documented. The range of motion of the elbow and forearm should be measured with the use of a goniometer. The examiner should confirm that the proximal radius articular deformity is the impediment to rotation. Motion can be lost as a result of soft tissue or osseous deformities. The synovial tissue in patients with hemophilic arthropathy is hypertrophic, highly vascular, and prone to impingement between the articular surfaces.²² A soft end point suggests a soft tissue cause, whereas a firm end point suggests osseous impingement. The distal radioulnar joint may be contributing to the forearm rotational stiffness.

Physical examination and imaging of the wrist are important, especially in patients with prior traumatic injuries, congenital deformities, and rheumatoid arthritis, in which distal radioulnar joint pathology is common. A careful examination of elbow and forearm stability is critical because valgus, posterolateral rotational, and axial instability are contraindications to radial head resection. Joint laxity may be caused by loss of articular cartilage, ligament attenuation resulting from chronic inflammation, or prior traumatic injuries. The examination for valgus instability includes valgus stress testing,²⁶^,²⁷ the milking maneuver,²⁸ and the moving valgus stress test.²⁹ The examination for posterolateral rotatory instability includes the pivot shift test,¹² the posterolateral drawer test,³⁰ and the supine and seated push-up tests.³¹^,³² Longitudinal radioulnar instability is difficult to detect on clinical examination. These patients often have tenderness or dorsal prominence of the ulna at the distal radioulnar joint.

As for any planned arthroscopic procedure, the location and function of the ulnar nerve should be assessed. A previous ulnar nerve transposition makes percutaneous placement of medial portals risky, and open placement is advocated to prevent iatrogenic nerve injury.

Diagnostic Imaging

Imaging can confirm the presence of a proximal radius articular deformity or arthritis (Fig. 10-1). In addition to anteroposterior and lateral views, a radiocapitellar view can help to throw the radial head into profile. Bilateral radiographs of the wrists should be performed to assess for other contributions to the painful or limited rotation, such as radioulnar synostosis or distal radioulnar joint pathology, and to assess for longitudinal radioulnar dissociation. Stress views or a fluoroscopic examination should be considered to rule out valgus, varus, and axial instability if there is any concern resulting from the physical examination. Computed tomography (CT) with sagittal, coronal, and three-dimensional reconstructions can better define the bony anatomy (Fig. 10-2). CT may offer additional information about the ulnohumeral, radiocapitellar, and proximal radioulnar joint spaces and about articular congruity. Loose bodies and heterotopic ossification also may be better defined. Resecting the radial head without addressing these other osseous deformities may result in suboptimal results.

FIGURE 10-1 Imaging was performed for a 65-year-old woman with Mayo grade III rheumatoid arthritis of the left elbow associated with intractable synovitis, painful rotation, and significant radial head deformity. Preoperative flexion was 15 to 140 degrees, with 60 degrees of pronation and 60 degrees of supination. The difference is shown between the preoperative anteroposterior (A) and lateral (B) radiographs and the anteroposterior (C) and lateral (D) radiographs obtained after arthroscopic radial head resection.

FIGURE 10-2 A 53-year-old woman has post-traumatic arthritis resulting from a remote elbow injury. She had undergone open débridement but presented with persistent posterior impingement and lateral elbow pain. Preoperative radiographs (A and B) and CT scans (C and D) reveal the radial head deformity. E, The radial head deformity is viewed from a proximal anteromedial portal. F, An arthroscopic view shows the associated full-thickness loss of capitellar articular cartilage. G, The burr is introduced from an anterolateral portal. H, An arthroscopic view shows the appearance after resection of the radial head. I, A lateral radiograph shows the joint postoperatively.

TREATMENT

Indications and Contraindications

The indication for arthroscopic radial head resection is proximal radius articular deformity or arthritis causing pain or impeding motion in the presence of competent medial and lateral collateral ligaments of the elbow and the interosseous membrane of the forearm. Limitation in rotation is particularly amenable to radial head resection. The radial head deformity can cause a mechanical block at the radiocapitellar or proximal radioulnar articulation, or both. The goal of this procedure is to remove the mechanical block, increase rotation, and decrease pain. If the capitellum is relatively intact and judged suitable for prosthetic replacement intraoperatively, radial head excision with prosthetic replacement may be preferred over radial head excision for the reasons previously discussed.

The most common conditions for which arthroscopic radial head resection has been described are rheumatoid arthritis ³^–⁵^,^20,²¹ and post-traumatic arthritis (particularly radial head fractures).²^–⁵^,^20,²¹ Radial head resection is sometimes indicated for hemophilic arthropathy of the elbow. Chronic hemophilic synovitis of the elbow can lead to enlargement and irregularity of the radial head. The margins of this hypertrophic radial head impinge against the proximal ulnar facet, acting as a mechanical block to forearm rotation. Reports in the literature of radial head resection for hemophilic arthropathy are limited to open techniques.²²^–²⁵ Congenital and acquired radial head dislocations can also be treated by arthroscopic radial head resection in selected cases. Surgical intervention is typically reserved for symptoms refractory to nonoperative measures, such as activity modification and anti-inflammatory drugs. In the setting of rheumatoid arthritis, this includes an adequate trial of disease-modifying medications.