Ectopic Ossification About the Elbow

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CHAPTER 31 Ectopic Ossification About the Elbow

ETIOLOGY

TRAUMATIC CONDITIONS THAT MAY LEAD TO ECTOPIC BONE FORMATION

Thompson and Garcia84 documented the incidence of ectopic bone formation in a series of more than 1200 traumatic elbow conditions: 3% in simple dislocations, 20% in elbow dislocations associated with radial head fractures, and 16% in elbow dislocations associated with other fractures. Although the definition of what constitutes ectopic bone is not clear, this report does serve as a worthwhile benchmark of the relative incidence among these three injury types.

Elbow Dislocations

Patients with simple dislocations without fracture are less likely to develop ectopic bone formation than are those with associated fractures.72,73 Linscheid and Wheeler51 noted an incidence of some radiographic density in about 30% in a series of 110 elbow dislocations. True ectopic bone formed in the anterior capsule in five patients (4.5%), and most had calcification in the collateral ligaments below the medial and lateral epicondyles (Fig. 31-1). Josefsson and colleagues42 found true ectopic bone formation in only 1 of 52 elbow dislocations (1.6%). Periarticular calcification, however, was noted in 38 patients (76%). Eleven of the 12 patients in whom there was no evidence of periarticular calcification had sustained their dislocations before the age of 16 years.

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FIGURE 31-1 Distribution of possible radiographic densities about the elbow after trauma.

(Redrawn from Broberg, M. A., and Morrey, B. F.: Results of treatment of fracture-dislocations of the elbow. Clin. Orthop. Rel. Res. 216:111, 1987.)

The incidence of ectopic bone formation increases about fivefold when an elbow dislocation is associated with a radial head fracture.84 McLaughlin55 listed several principles to reduce the formation of ectopic bone: (1) excision of the radial head within 24 hours of injury, (2) complete removal of the radial head with all the fracture fragments, (3) avoidance of the formation of bone dust within the operative bed at the time of radial head excision, (4) careful hemostasis, and (5) avoidance of hematoma formation. There is little scientific evidence to support these recommendations, but they seem reasonable.

Radial Head Fractures

Ectopic bone formation may also occur following isolated fractures of the radial head. Patients with Mason type III comminuted fractures are probably at the greatest risk.52 In a study of 60 cases, Mikic and Vukadinovic56 noted ossification about the elbow in 32 (56%). In the 18 patients with more extensive amounts of bone, restriction of elbow motion was seen in all. In 31 (52%) of these patients, there was significant regrowth of bone at the level of resection of the radius, as noted by others.48,81 We have observed a rather consistent pattern of ectopic bone emanating from the resected radius in this clinical circumstance (Fig. 31-2).

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FIGURE 31-2 Temporal correlation of radiographic and serum alkaline phosphatase changes with clinical symptoms.

(Redrawn from Orzee, J. A., and Rudd, T. G.: Heterotopic bone formation: clinical, laboratory, and imaging correlation. J. Nucl. Med. 26:125, 1985.)

Timing of Surgical Treatment with Elbow Trauma

We have observed that patients with open injuries undergoing several surgical procedures performed during the first 7 to 14 days of injury are at particular risk (Fig. 31-3). In McLaughlin’s series of radial head fractures,55 12% who underwent excision within 24 hours had ectopic bone formation, compared with 38% who had delayed excision.

In a study of 14 patients with fracture-dislocations of the elbow treated by either partial or complete resection of the radial head, Broberg and Morrey8 reported an incidence of significant ectopic bone formation of only 9%. The single patient with significant heterotopic ossification had undergone excision of the radial head 8 days after injury, and the results of treatment were graded as fair with continued elbow pain.

The issue of delay before definitive surgery for fracture dislocation was initially emphasized by McLaughlin.55 This opinion has been recently strengthened by the work of Ilahi and colleagues.41 Among 71 consecutive elbow injuries of various types, none developed significant ectopic bone when operated on within 48 hours. On the other hand, 8 of 24 (33%) did enounter ectopic bone formation if treatment was delayed more than 48 hours.

Post-Traumatic Radioulnar Synostosis

Cross-union from ectopic bone may be caused by fractures,5,11,23,65,75,85 or soft tissue injury7,60,70 of the forearm. When an associated elbow injury has occurred, the synostosis may be extensive (Fig. 31-4).

Vince and Miller86 classified synostoses of the forearm by location: type I, distal third; type II, middle third; and type III, proximal third. Two of three patients with proximal synostoses who were treated surgically had unsatisfactory results because of recurrence of the synostosis. Failla and associates22 reported a series of 20 patients from the Mayo Clinic who underwent excision, with only 7 patients achieving good or excellent results and 13 patients achieving fair or poor results. The timing of synostosis excision appeared to be important, with no good or excellent results in patients operated on less than 12 months after injury or more than 3 years after injury. We use the radiographic appearance of discrete margins and mature trabeculation as the basis of when to resect the lesion. Bone scans and serum enzymes are of little value in deciding when to resect the lesion, and hence, we do not obtain these studies.

Jupiter and Ring43 subclassified type III forearm synostosis into three types based on the location of theectopic bone. Type III A ectopic ossification is located at or distal to the bicipital tuberosity, Type III B involves the radial head and/or proximal ulnar joint, and Type III C refers to a proximal radial ulnar synostosis contiguous with ectopic bone extending across the elbow to the distal humerus. Eighteen patients underwent operative excision of post-traumatic proximal radioulnar synostosis. Recurrence was seen in only one patient. The 17 patients who did not experience a recurrence regained an average of 139 degrees of forearm rotation. No significant relationship between postoperative forearm rotation and synostosis size, the use of interpositional fat, or the concomitant use of a hinged elbow distractor was identified.43

The surgical treatment of proximal radioulnar synostosis has traditionally been viewed with pessimism. This view has been based on very little published data. The importance of forearm rotation to patient function is well established, and recent experience demonstrates that surgical excision is warranted and is likely to be successful.43

Preoperative planning is necessary to choose the correct surgical approach to remove the entire lesion if this is deemed necessary. CT scans or tomograms can be used to define the anatomy of the synostosis.

If possible, the entire lesion must be resected, and the radius and ulna in the area of the synostosis must be contoured to allow motion without impingement. The intimate proximity of neurovascular structures may limit this resection. Ideally, a free space of at least 5 mm should be created and maintained throughout the intraoperative arc of motion. We prefer not to interpose Silastic or other foreign material, but we do translocate fat into the defect. Patients can be expected to lose about 50% of the intraoperative motion achieved. Accordingly, the surgeon should attempt to achieve at least 120degrees of combined supination and pronation intraoperatively.

An alternative surgical approach to improve forearm rotation in this difficult clinical setting is proximal radial resection as described by Kamenini and Morrey44 (Fig. 31-5). Indications include (1) extensive synostosis not amenable to a safe and discrete resection, (2) articular surface involvement, and (3) associated anatomic deformity. A Kocher approach is recommended to explore the synostosis and the radius distal to the synostosis. One centimeter of bone is excised from the radius, and the remaining exposed bone is covered with bone wax. Postoperative arc of forearm rotation averages 98 degrees. Reankylosis occurred at the site of resection in one patient.

CLASSIFICATION

There are several discrete clinical circumstances in which ectopic bone develops around the elbow: (1) trauma, usually fracture; (2) closed head or spinal cord injury; (3) burn injury to the extremity; and (4) genetic conditions (Box 31-1). Recently, the process has also been reported to occur after adult respiratory distress syndrome37 and after orthotopic liver transplant.62

Radiographically, ectopic bone is seldom seen before 3 weeks after injury or surgery, but it usually can be detected if one looks for it critically. The soft density on the radiograph can be visualized under a bright light. The extent of ectopic bone formation usually is evident by 12 weeks (Fig. 31-6). Bressler and colleagues9 studied the maturation process of ectopic bone in 25 CT scans. Persistent, unossified, low-density soft tissue areas were detected adjacent to mineralized areas up to 16 years after injury. In adults, after the maturation process is completed, the bone usually does not resorb. Resorption may occur in children younger than 16 years. Ectopic ossification may be classified by its anatomic formation site or its functional affect on elbow motion and forearm rotation.

FUNCTIONAL CLASSIFICATION

Hastings and Graham38 have developed the classification based on functional range of motion of the elbow and forearm rotation. Class I ectopic bone refers to the radiographic appearance of abnormal bone without any functional limitations. This should be documented because it signifies a patient’s tendency toward heterotopic bone formation. Prophylactic treatment may be warranted in these patients.

Class II refers to patients with limited range of motion. Class II is subdivided into three types. Class II A refers to limitation of motion in the flexion/extension arc, class II B is limited forearm rotation, and class II C has limitation in both planes. Patients with class III ectopic ossification have ankylosis that eliminates either elbow flexion and extension, pronation and supination, or both. This class is subdivided into three types that are identical to class II.

INCIDENCE OF ECTOPIC BONE FORMATION

ECTOPIC BONE FORMATION FOLLOWING CENTRAL NERVOUS SYSTEM INJURY

First described during the First World War,16 ectopic bone formation may occur after central nervous system (CNS) injury to the brain or spinal cord.29,72 Garland and others29,35,40 extensively studied the orthopedic problems encountered by patients with both traumatic brain injury and spinal cord injury (see Chapter 72).

Traumatic Brain Injury without Elbow Trauma

In a review of 496 patients with traumatic brain injury, Garland and colleagues32,33 found an incidence of periarticular bone formation in 100 joints in 57 patients (11%). Patients with spastic quadriparesis have the highest incidence of ectopic bone formation. The hip was the most common location, followed by the shoulder, elbow, and knee. Ectopic bone formation developed in 4% of the elbows. Anterior bone formation was deep to the biceps and brachialis muscles and anterior to the joint capsule, occasionally involving the entire brachialis muscle (Fig. 31-7). The posterior ectopic bone was beneath the triceps tendon in close association to the posterior capsule. In Garland’s series,32 the ectopic bone was anterior in six and posterior in 17, and eight of the elbows were completely ankylosed preoperatively. Posterolateral ectopic bone formation is the most common site of occurrence.30

A major determinant of potential successful surgical treatment is the residual neurologic deficit. Twenty-three patients underwent resection of ectopic bone about the elbow. In general, resection should be delayed until at least 18 months after CNS injury to allow maximum functional recovery. The results of excision correlate with the neurologic classification.32

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