CHAPTER 31 Essex-Lopresti Fractures
Injury Pattern and Biomechanics
When a fall on an outstretched hand leads to a comminuted radial head fracture, longitudinal radioulnar dissociation (LRUD) may result if the forearm interosseous ligament (IOL) tears as well. This is often referred to as the Essex-Lopresti lesion. This injury pattern was initially described by Curr and Coe in 1946,1 but Essex-Lopresti illustrated the importance of diagnosing longitudinal radioulnar instability.2 Fracture of the radial head, disruption of the central third of the IOL, historically referred to as the interosseous membrane,3–7 and injury to the distal radioulnar joint (DRUJ), contribute to loss of forearm stability. In LRUD, lack of forearm stability leads to loss of forearm rotation, decreased wrist extension, ulnar wrist pain, and elbow pain.3–7 Understanding normal forearm biomechanics facilitates treatment of this challenging clinical problem.
The biomechanics of the forearm axis are best explained in terms of load transfer and stability. With use of the hand, and forceful grip, forces are transferred through the wrist to the elbow via the forearm IOL. Abnormal load transfer may result in pain secondary to abnormally high joint contact stresses at the elbow and ulnocarpal joints. As the forearm is loaded axially in compression, the IOL is loaded in tension. The IOL functions not only to transfer load from the radius to the ulna but also to pull the radius and ulna together at the proximal and distal radioulnar joints (Fig. 31-1).8–12 Numerous studies have shown that the IOL and the triangular fibrocartilage complex (TFCC) help to provide stability to the DRUJ.13–17
Diagnosis
With a high-energy axial load applied to the forearm through the wrist, the radial head can fracture. With enough energy, the IOL and DRUJ can also be disrupted. Injury to the IOL and DRUJ can be easily overlooked if attention is focused on the radial head fracture alone.18 After a few weeks, patients with LRUD can present with ulnar-sided wrist pain, loss of forearm rotation, and elbow pain. Physical examination will show painful rotation and ulnar deviation, forearm swelling, and lateral elbow tenderness.
Minimal radial shortening of up to 2 mm may be expected with a simple fracture of the radial head.19,20 However, greater than 2 mm of radial shortening and radial head comminution are strongly suggestive of LRUD (Fig. 31-2).21
Edwards and Jupiter22 proposed a classification system for the Essex-Lopresti type radial head fractures:
Patients presenting with a comminuted radial head may present acutely with symptomatic LRUD, but they also have the potential to develop late LRUD. Although patients with LRUD may present acutely with wrist pain and forearm swelling, this is typically not the case. Forearm and wrist films should be obtained along with elbow films. Magnetic resonance imaging and ultrasonography have also proved useful in imaging IOL tears.23–27 Radius stability can be assessed intraoperatively by applying axial load to the radius (“shuck” test). Proximal migration of the radius in late LRUD may be frank or occult. In frank cases, LRUD is seen on plain radiographs. In occult cases, power grip and axial stress views may elicit ulnar-positive variance.28,29 Proximal migration of the radius may be fixed or reducible; distinguishing this can help guide treatment. If frank, dynamic fluoroscopic evaluation utilizing finger traps can illustrate if the deformity is reducible, then ulnar-positive variance may be “reduced” to ulnar-neutral variance. In the occult case, ulnar-positive variance is, by definition, dynamic.
Current Treatment and Surgical Technique
When the IOL is torn, the radial head is essential for maintaining longitudinal stability. If ORIF is not possible, radial head arthroplasty functions to share the load at the elbow and prevent proximal migration of the radius. Although Silastic radial heads have been used in the past, nonmetallic implants have been shown to collapse over time and may cause synovitis.16,30–33 Metallic prostheses are stiffer than Silastic ones and are more effective in preventing proximal migration of the radius.34–37 However, long-term clinical results of metallic radial heads in cases of LRUD are still lacking in the literature. There may be complications due to implant loosening and dislocation and elbow stiffness and capitellar wear from oversizing the implant.
Modular radial heads offer a more anatomical design. Grewal and associates recently reported favorable short-term clinical results at 2 years with modular radial head replacement for comminuted radial head fractures.37 Even though this study lacked a control group, the authors found no evidence of overstuffing and 81% did not have arthritic changes. However, the outcomes of modular radial heads in patients with Essex-Lopresti fracture-dislocations in particular remain to be seen.
Treatment of Acute LRUD
The overall goal of treatment is to restore load sharing between the radius and ulna and prevent long-term proximal migration of the radius. The structures that require attention include the radial head, the TFCC, and the IOL. The radial head should be preserved if ORIF is possible. However, comminution of the radial head may prevent repair. Therefore, restoring radial length will require metallic radial head arthroplasty (Fig. 31-3). In addition, pinning of the DRUJ for 4 weeks is recommended to allow the TFCC and DRUJ capsule to heal. Furthermore, because failure of this acute treatment strategy has significant consequences, and as the technique of open foveal reattachment of the torn TFCC has been refined, we advise a more aggressive approach to address the wrist after radial head replacement and restoration of the normal radioulnar relationship—open TFCC repair plus DRUJ pinning. This will ensure as precise a restoration of normal anatomy at the wrist as possible.
Contraindications
Silastic radial heads and radial head allografts are contraindicated. Any decision to salvage the radial head fracture must be based on feasibility of repair. Metallic radial head arthroplasty is probably the better option when comminution exists such that rigid fixation and articular reconstruction are not possible.
