Congenital proximal radioulnar synostosis is a rare congenital anomaly characterized by a fixed position of the forearm ranging from neutral rotation to maximum pronation. Early reports of the operative treatment of this condition describe restoration of motion by resection of the synostosis and interposition of fat or muscle2,13. However, this procedure led to uniformly poor results. Dal Monte et al. released the synostosis in twelve patients by removing the part of the radius that was proximal to the synostosis and, in some patients, by using aponeurotic or muscle flaps to preserve the separation of the radius and ulna. Those authors reported recurrence of a synostotic bridge in every patient. Sachar et al. did not recommend resection of the synostosis for the treatment of recurrent ankylosis in infants less than one year old who have a reduced radial head and a limited synostosis.
In a review of reports of mobilization procedures and their outcomes, we found that the procedure had failed in all but one of twenty-two patients (twenty-three forearms)2,3,7,11,13. The one patient who had a successful result was a thirty-three-year-old woman who gained a 60-degree arc of motion after five operations3.
We present the results of our technique for mobilization of the synostosis by separation of the synostosis and interposition of a free vascularized fascio-fat graft between the separated radius and ulna. The operation was done in seven patients, and osteotomy of the radius to prevent recurrent dislocation of the radial head was also performed in four of them as a primary procedure and in one as a secondary procedure.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
†Read at the Annual Meeting of the American Society for Surgery of the Hand, San Francisco, California, September 14, 1995.
‡Department of Orthopedic Surgery, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0125, Japan. E-mail address for Dr. Kanaya: fkanaya@med.u-ryukyu.ac.jp.
We performed the index procedure on seven boys (seven forearms) who had a proximal radioulnar synostosis without other congenital anomalies (Table I). All patients had limited rotation of the forearm regardless of the degree of the pronation deformity. Three patients had bilateral ankylosis, and the operation was performed on the dominant side (two operations were done on the right side, and one was done on the left side). The average age at the time of the operation was eight years and two months (range, six years and four months to eleven years and ten months).
Preoperatively, the forearm was ankylosed between neutral and 80 degrees of pronation in six patients and in 30 degrees of supination (after a previous mobilization procedure had failed) in one patient. The four patients who had a unilateral synostosis had limited rotation of the contralateral forearm (average, 51 degrees of supination and 52 degrees of pronation). The radial head was dislocated in all seven patients (anteriorly in two and posteriorly in five). All patients had had difficulty with holding a bowl of soup and accepting objects, such as coins, into the palm. Six patients had difficulty with performing gymnastics and throwing a ball. One patient (Case 7) could neither hold a glass to drink nor wash his face with the affected hand.
The average duration of follow-up was three years and eight months (range, two years and four months to four years and five months).
Operative Technique (Figs. 1-A, 1-B, 1-C, 2-A, 2-B, 2-C through 2-D)
Separation of the Synostosis
The synostosis was separated through an anterior and posterior approach. Preoperative computerized tomographic scans helped the surgeon to determine the direction of separation8.
The posterior approach was performed first, through a skin incision starting from the lateral epicondyle and curving dorsally to reach the posterior crest of the ulna. The anconeus was identified, and its insertion was detached from the ulna with a periosteal slip for later reattachment. The anconeus was reflected proximally to expose the posterior aspect of the synostosis (Fig. 2-A). The proximal and distal borders of the synostosis were identified with use of injection needles. The interosseous recurrent vessels, which were consistently found at the distal margin of the synostosis, were a good landmark for identifying the distal border of the synostosis. The length of the synostosis ranged from three to five centimeters. A synchondrosis between the radial head and the ulna was seen in all patients. Separation of the synchondrosis and synostosis was accomplished with use of a steel burr on a high-speed drill. In addition, the drill was used to shave the radius and ulna one centimeter distal to the synostosis. The biceps tendon, primarily at its insertion on the volar aspect of the synostosis, inevitably was detached during separation of the synostosis.
Shaving of the radial head was necessary to achieve rotation of the forearm. The dislocated radial head, which was conical in the sagittal plane, was trimmed flat in that plane and was trimmed to a semicircular shape in the horizontal plane with use of a knife and a steel burr on a high-speed drill. (A normal radial head is concave in the sagittal plane and circular in the horizontal plane.) Exposure of the epiphyseal nucleus was carefully avoided.
The anterior approach was performed through an s-shaped incision, approximately five centimeters in length, over the anterior aspect of the proximal end of the forearm. The biceps tendon, supinator muscle, brachial and radial arteries, radial recurrent vessels, and median and radial nerves were identified. Detachment of the residual biceps tendon from the ulna improved rotation of the forearm and exposed the space created by separation of the synostosis.
Osteotomy of the Radius
The dislocated radial head could be reduced manually in all patients, but it redislocated during rotation of the forearm. An osteotomy of the radius was not performed at the time of the index procedure in the first three patients who were managed (Cases 1, 2, and 3). In the remaining four patients (Cases 4 through 7), a shortening-wedge osteotomy was performed between the insertion of the supinator and pronator muscles in conjunction with the index procedure (Table I). In one patient (Case 2), the osteotomy was done two years and eight months after the index procedure to reduce the dislocated radial head. A flexion osteotomy was done when the dislocation was posterior, and an extension osteotomy was done when the dislocation was anterior. The dislocated radial head seemed to reduce rotation of the forearm. Because the radius is bowed to a greater degree than normal and is longer than the ulna, we shortened and rotated the radius in order to reduce the radial head and the bowing of the radius.
The radius was sectioned between the insertion of the pronator teres and the supinator, and the radial head then was reduced (Fig. 2-B). The osteotomized ends of the radius overlapped during the reduction. A trapezoid-shaped wedge of bone was removed, with the longer base (three to twenty-two millimeters in length) placed posteriorly when the dislocation was anterior and anteriorly when the dislocation was posterior. The osteotomy site was stabilized with use of a four-hole titanium plate (Fig. 2-C). The distal aspect of the radius was supinated so that the center of rotation corresponded with neutral rotation. However, the desired rotation was not always achieved because of soft-tissue tightness.
Soft-Tissue Reconstruction
The dissected portion of the capsule around the radial head was carefully reefed in all seven patients. The annular ligament, identified in two patients, also was reefed. The detached biceps tendon was pulled dorsally and sutured to the dorsal cortex of the radius with a pull-out technique and 4-0 nylon suture. The anconeus muscle was pulled anteriorly and sutured to the brachialis tendon to fill the proximal one-fourth to one-third of the space created by separation of the synostosis.
Vascularized Fascio-Fat Graft
The vascularized fascio-fat graft, which included a small skin flap for use in monitoring the viability of the flap, was obtained from the ipsilateral arm (Fig. 2-D). The procedure was identical to that used to obtain a lateral arm flap, with the profunda humeri vessels serving as the donor vessels. The fascio-fat graft was larger than the space created by separation of the synostosis. The graft was placed in the space between the separated radius and ulna in a volar-to-dorsal direction. The profunda humeri (donor) vessels were anastomosed with the recurrent radial (recipient) vessels. The small skin flap was sutured to the dorsal skin, and the wound was closed after the sufficiency of the blood flow to the flap had been confirmed.
Postoperative Care
Postoperatively, an above-the-elbow plaster cast was applied with the elbow in 90 degrees of flexion and the forearm in neutral. There were no problems with circulation; however, if the flap had demonstrated poor circulation, we would have reanastomosed the vessels. The cast was removed after three weeks, and active range-of-motion exercises and activities (such as playing with toys, swimming, and throwing a ball) were encouraged. After three months, we encouraged the patients to participate freely in sports activities.
CASE 7. A six-year and seven-month-old boy had a congenital radioulnar synostosis in the left forearm, which was ankylosed in 80 degrees of pronation. He had only 20 degrees of supination and 30 degrees of pronation of the right forearm. Anteroposterior and lateral roentgenograms revealed a proximal radioulnar synostosis with posterior dislocation of the radial head (Figs. 3-A and 3-B). Computerized tomographic images showed the complete synostosis between the radius and ulna with a thin septum (Fig. 3-C).
Intraoperatively, there was a synchondrosis between the radial head and the proximal aspect of the ulna as well as a radioulnar synostosis that was forty millimeters in length. There was no annular ligament, the capitellum was hypoplastic, and the radial head was conical. The posterior aspect of the capitellum articulated with the anterior aspect of the radial head. Separation of the synostosis left a space that was fifty millimeters long and nine millimeters wide. An osteotomy of the radius was performed in conjunction with the index procedure.
Two years and six months after the operation, there was no evidence of recurrence of the ankylosis and the radial head was still in a reduced position (Figs. 3-D and 3-E). The vascularized fascio-fat graft could be seen between the separated radius and ulna on computerized tomographic images (Fig. 3-F). The patient had 10 degrees of supination and 70 degrees of pronation, and he was able to perform gymnastics.
During the first year after the operation, rotation of the forearm continued to improve, and it essentially remained unchanged thereafter. All patients reported improvement in the ability to perform gymnastics; throw a ball; hold a bowl of soup; and accept objects, such as coins, into the palm. There were no neurological or vascular complications. The only donor-site morbidity was the scar. No patient had recurrence of the ankylosis or loss of the flap.
The average arc of motion was 71 degrees: the average supination was 26 degrees (range, 10 to 45 degrees), and the average pronation was 45 degrees (range, 10 to 80 degrees). The four patients who had had an osteotomy of the radius at the time of the index procedure had union at the site of the osteotomy. None of these patients subsequently had a dislocation of the radial head, and the average arc of motion was 83 degrees (average supination, 26 degrees, and average pronation, 56 degrees). In contrast, the radial head dislocated in the remaining three patients with range-of-motion exercises; these patients had an average arc of motion of 40 degrees. The patient (Case 2) who had an osteotomy of the radius performed two years and eight months after the separation of the synostosis had union of the osteotomy site and improvement in rotation of the forearm from 30 to 75 degrees (Table I).
Congenital proximal radioulnar synostosis, a deformity characterized by a fixed position of the forearm ranging from neutral rotation to maximum pronation, is a rare congenital anomaly. Sachar et al. noted approximately 350 cases in the literature. The condition can be extremely disabling, especially when it occurs bilaterally or if there is severe hyperpronation. Patients who have a severe deformity have trouble bringing a cup to the mouth, using utensils, or accepting objects into an open palm14.
Hansen and Andersen classified the synostosis roentgenographically into two types. Cleary and Omer described four types: in type 1, there is a lack of involvement of the bone and the radial head is located and normal; in type 2, there is a visible osseous synostosis with a normal radius; in type 3, there is an osseous synostosis with a hypoplastic and posteriorly dislocated radial head; and in type 4, there is a short osseous synostosis with an anteriorly dislocated radial head. According to the classification system of Cleary and Omer, five of our patients had a type-3 and two, a type-4 synostosis. However, because there is little functional difference between the radiographic types1 and the classification changes with time, these systems may have little clinical value11.
Mobilization of a proximal radioulnar synostosis is still a challenge for the orthopaedic surgeon. The ability to rotate the forearm improves the patient's ability to perform activities of daily living and increases the patient's choices with regard to future endeavors. Currently, osteotomy to achieve a neutral or slightly pronated position is widely accepted for the management of patients who have severe pronation6,12,14. However, the optimum position of the forearm after the osteotomy remains controversial. The ideal position depends on the type of involvement (bilateral or unilateral, dominant or non-dominant side), the social and cultural environment of the patient, and projected future activities12. Because it is not possible to predict future activities, it is impossible to determine the optimum position of the forearm. Although rotational osteotomy is currently an accepted treatment for synostosis, we believe that successful mobilization will improve the performance of activities of daily living more than a rotational osteotomy will.
Several authors have reported separation of the synostosis and interposition of fat or muscle (or some other material), but recurrence of the ankylosis has still been noted2,7,11,13. Hansen and Andersen performed a partial resection of the left radius in a sixteen-year-old girl. Eighteen months postoperatively, osseous contact was noted roentgenographically. Miura et al. operated on eight upper extremities in seven patients. They placed the anconeus between the separated radius and ulna, but the synostosis recurred in every patient. Kelikian and Doumanian reported good results with use of a swivel prosthesis in patients who had a post-traumatic proximal radioulnar synostosis; however, Tachdjian noted disappointing results with the swivel prosthesis in patients who had a congenital synostosis, with recurrence of the ankylosis at the eighteen-month follow-up examination.
Simmons et al. reported eight complications in association with twenty-two osteotomies; the complications included a wound infection (one), loss of correction (three), and circulatory problems (four). Green and Mital reported one ischemic contracture in thirteen patients. Wide exposure and careful protection of the neurovascular structures may be the reason why none of our patients had neurovascular complications in contrast to those who have been reported on in the literature.
The space created by separation of the synostosis should be filled with a substance that prevents both bone and scar formation. Gill et al.4 found that free fat grafts prevented scar formation better than did Gelfoam or Micropore or other plastics after laminotomy in fifty dogs. They also found that the pedicle fat graft was better than the free fat graft not only for the prevention of scar-tissue formation but also for the prevention of the usual osseous closure after laminotomy. Those authors also demonstrated the viability of the pedicle fat graft histologically in patients who had a second procedure on the lumbar spine5. Langenskiöld and Valle, using computerized tomography, demonstrated the viability of free fat grafts that had been transplanted onto the dura fifteen to eighteen years earlier in four patients.
The results that have been obtained with use of free fat grafts encouraged us to believe that vascularized fat grafts would be ideal for preventing recurrent ankylosis caused by the formation of synostotic bridges and scars; we also thought that the fat would allow the space between the separated radius and ulna to be maintained for a long time. Because a satisfactory amount of tissue cannot be obtained from around the elbow joint, we used a free vascularized fascio-fat graft to fill the space created by separation of the radioulnar synostosis and to avoid recurrent ankylosis and scar formation. Obtaining this graft was the same as obtaining a lateral arm flap, and the procedure proved to be safe and relatively easy. Because we obtained only a small island of skin, donor-site morbidity was minimum and closure was not difficult. We chose the lateral aspect of the ipsilateral arm as the donor site so that all procedures would be confined to one extremity. We used a free flap rather than a distally based pedicle fascio-fat graft from the lateral aspect of the arm (an attractive alternative because it does not necessitate anastomosis of pedicle vessels) because we could not obtain satisfactory circulation with use of the pedicle graft in our first three patients. This problem may have been the result of the anomalous course of the posterior interosseous recurrent vessels that run dorsally around the distal margin of the synostosis. We subsequently used a free vascularized fascio-fat graft in these patients and in every patient thereafter.
In summary, we found that separation of the radioulnar synostosis with use of a vascularized fascio-fat graft as an interpositional material prevented recurrence of ankylosis and improved rotation of the forearm. We believe that our results justify the use of an osteotomy of the radius to prevent disclocation of the radial head; this procedure appears to improve rotation of the forearm as well.