Outcomes of derotation osteotomy at synostosis site for congenital radioulnar synostosis

Outcomes of derotation osteotomy at synostosis site for congenital radioulnar synostosis

Tazi Charki Mohammed^1,&, Abdellaoui Hicham¹, Atarraf Karima¹, Chater Lamyae¹, Afifi Moulay-Abderahman¹

¹Department of Orthopaedic Paediatric, University Sidi Mohammed Benabdellah, University Hospital Hassan II, Fez, Morocco

^&Corresponding author
Tazi Charki Mohammed, Department of Orthopaedic Paediatric, University Sidi Mohammed Benabdellah, University Hospital Hassan II, Fez, Morocco

Introduction    

Congenital radioulnar synostosis (CRUS) is a rare upper limb malformation [1]. Since the first description by Sandifort in 1793 [2], only 350 cases have been reported in literature heretofore [3]. It is thought to be caused by a failure of longitudinal segmentation with persistence of the cartilaginous anlage between the radius and ulna during the seventh week of development. The resultant bridge may be fibrous or bony [4,5]. CRUS may be isolated or associated with other abnormalities such us brachydactyly, polydactyly, syndactyly and Madelung's deformity and can be a part of syndromes (arthrogryposis, Apert´s syndrome, Carpenter´s syndrome, Williams' syndrome) [6]. The patients with CRUS have a fixed forearm in positions that vary from neutral rotation to considerable pronation. In cases with severe deformity, performing activities of daily living is difficult, and surgical interventions is recommended [7-9]. Two types of surgical treatments have been described: mobilization of the synostosis which frequently results in recurrence of the fusion with unsatisfactory results [6,10-12], and rotational osteotomy, which provides functional improvement [8,13-15]. Recently, a free vascularized fascial flap placed between the separated forearm bones has been reported to successfully block postoperative recurrence of the synostosis [16,17]. Many types of rotational osteotomy was described, they can be summarized into osteotomy at the synostosis, osteotomy at two sites in the diaphysis of the radius and the ulna, and osteotomy at one site in the distal diaphysis of the radius [6,18,19]. In our department we performed osteotomy in synostosis site. We present in this study the outcome of this technique.

Methods     

It´s a retrospective study including all patient operated for CRUS between January 2009 and December 2017 in the Pediatric Orthopedic Department Of University Hospital Hassan II of Fez (Morocco). Post traumatic synostosis and non-operated CRUS was excluded from the study. The indication for surgery was a pronation deformity upper to 60 degree and an important limitation in performing the activities of daily life or bilaterality regardless of the degree of pronation. Preoperative clinical assessment included the ability of performing the activities of daily life and degree of pronation deformity that was measured by the angle between the longitudinal axis of the humerus and the line of radial and ulnar styloid processes (forearm rotation). Classification of Cleary and Omer [4] was used for radiological assessment (Table 1). All patients were operated under general anesthesia in supine position with image intensifier guidance. Posterolateral approach of 3 to 4 cm was used to expose the synostosis (Figure 1). Derotation on neutral, 10^o or 30^o of pronation was performed after sub-periostal osteotomy of the synostosis using an oscillating saw. Fixation was made by 2 Kirschner wires (K-wire) (Figure 2). An above elbow cast was applied with the elbow flexed at 90^o. Close observation for neurovascular complications was performed during 24 to 48h. The casts were removed after 4 weeks and K-wire after union. Patients were re-examined at 10 days, 4 weeks, 3 months, 6 months, 1 year, and afterwards every year. The time required for bone union, the correction angle obtained, activities of daily living improvements, and postoperative complications were investigated. Postoperative follow-up was made once a year after 6 months of follow-up.

Results     

Between 2009 and 2017, ten patients (7 male and 3 females) with CRUS were operated in our department. Five patients were unilateral (3 right and 2 left) and five were bilateral, but only one patient was operated for both sides (3 patients had no surgical indication for the contralateral synostosis, one patient not yet operated, and one refused surgery after complication in the first side). In all, out of 15 synostosis, 11 were operated. The mean age was 5 years (range 3-10 years). None of the children had associated abnormalities. Preoperative assessment revealed limitation of the activities of daily life in all patients with an average pronation deformity of 62^o (range, 45^o-85^o). According to Cleary and Omer classification, synostosis were type II for one CRUS, Type III for nine, and type IV in one case (Table 2). Post operative assessment showed bone union in 9 patients (10 forearms) within an average period of 12 weeks (range8-16 weeks). Non-union and loss of correction had occurred in patient who presented a postoperative compartment syndrome requiring discharges aponevrotomy and removal of K-wire. The mean follow-up period was 4.2 years (range 1-10 years). The average correction of the forearm angle was 54^o (range, 30^o-75^o). Nine patients were satisfied and showed improvements in the ability to perform the activity of daily life (Figure 3). The patient presenting non-union has developed a shortening of forearm and limitation in performing the activities of daily life.

Discussion     

CRUS is a rare anomaly of the upper limb that can cause significant disability when the deformity is severe or bilateral [6]. Bilaterality is found in 50 to 80% of cases [1,11]. In this series, 50% of patient had bilateral involvement. Authors [8,15,16,20] found, as we did, that males are more frequently affected (60-77%) and type III of Cleary and Omer [4] classification was the most common. Regarding the suitable age for surgery, most authors recommended that operation is best carried out between the ages of 3 and 6 years. At these ages, the osteotomy will be easy with sufficient remodeling. In older patients, the risk for neurovascular complications may increase [6,15,18,19]. The mean age of our series was 5 years (range 3-9 years). Most authors considered that pronation deformity of 60^o or more and bilateral synostosis with pronation of 20^o to 60 were a definite indication for surgery, while pronation of 20^o to 60^o in unilateral cases was a relative indication based on the severity of disability and the needs of individual [1,15,21,22]. At present, two major surgical procedures are available to treat CRUS. The first option is to separate the radioulnar synostosis and restore forearm rotation. This technique is thought to be the best method theoretically. However, the results are disappointing with high rate of recurrent fusion [11,12]. Kanaya and Ibaraki have reported a technique of free vascularized fascial flap placed between the separated forearm bones to successfully block postoperative recurrence of the synostosis [16]. Despite the good results, the methods requires meticulous technique and high-risk surgical procedure that prevents it from being used widely [8]. The second surgical option is derotation osteotomy to realign the forearm in suitable position to facilitate activities of daily living, taking into account that patients with congenital radioulnar synostosis have considerable compensatory movement around the wrist and the shoulder [8,22]. Three types of osteotomy procedures have been used: osteotomy at the synostosis site was recommended by many investigators [22-24]. But a high incidence of complication has been reported, including vascular compromise, such as Volkmann´s ischemia, shortening and angulation of the forearm, and posterior interosseous nerve palsy [4,21-26]. It is thought that the critical rotation takes place over a much more narrow space and the excessive soft-tissue tightness may result in the loss of correction, a circulatory compromise, or a neural entrapment [8,13]. Some authors propose to perform a shortening of 5 mm in synostosis site to decrease the tension of the soft tissue [22,27]; osteotomy at one site in the distal diaphysis of the radius [19] and osteotomy at two sites in the diaphysis of the radius and the ulna. Authors report good results with few neurovascular complications with this technique [1,8,13,15,20]. Hwang ^{et al}. [7] proposed segmental bone resection and osteotomies at different sites. Many authors report that complications increase with age [8,15,19]. In our series, we have performed osteotomy at synostosis site, and compartmental syndrome was described in an 8-year-old. The optimal position of the forearm after rotation is controversial, involving customs, dominance, the involved side and individual need [7]. Green and Mital stated that in bilateral cases the dominant hand should be placed 20^o and 35^o of supination and the other should be left in considerable pronation, whereas in unilateral cases a 10^o to 20^o is ideal [24]. Ogino and Hikino recommended that for unilateral cases or the nondominant hand of bilateral cases the forearm should be corrected to between neutral and 20^o of supination, and for the dominant hand of bilateral cases it should be corrected to between neutral and 20^o of pronation [22]. Moreover, position depends also on the customs; western people use knives and forks for eating, and do not need full supination of the forearm to do this. Contrariwise, Eastern Asian people require sufficient forearm supination to use chopsticks [8,13]. With the increase in computer use over the past decade, however, people have begun to use keyboards much more frequently. Fixed supination of the forearm requires shoulder abduction and internal rotation to bring the forearm into pronation, and prolonged maintenance of this position during keyboarding is extremely fatiguing. In our series, forearms were fixed in neutral, 10^o or 30^o of pronation.

Conclusion     

In summary, CRUS is a rare deformity, frequently bilateral and more commonly seen in male patients. Indications for surgery are pronation deformity of 60^o or more, bilaterality and pronation of 20^o to 60^o with disability. There is no consensus about the optimal angle of forearm rotation. It has been reported that complications are more common in osteotomy in synostosis site. In our series, one case of complication was reported.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

All authors have read and approved the final version of the manuscript.

Tables and figures     

Table 1: the cleary and omer classification

Table 2: preoperative and post-operative data of the patients

Figure 1: exposition of radioulnar synostosis

Figure 2: fixation of derotation by 2 K-wire

Figure 3: post-operative result of bilateral synostosis

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