Monteggia fracture-dislocation was described. Posterior interosseous nerve entrapment after Monteggia fracture-dislocation in children

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1 Original articles Posterior interosseous nerve entrapment after Monteggia fracture-dislocation in children LI Hai, CAI Qi-xun, SHEN Pin-quan, CHEN Ting, ZHANG Zi-ming, ZHAO Li* Abstract Objective: Although most of nerve injuries associated with Monteggia fracture-dislocation in children are neurapraxias and will recover spontaneously after conservative treatment, surgical exploration of the involved nerve is always required in the cases with the entrapment of posterior interosseous nerve (PIN). However, the necessity and time frame for surgical intervention for specific patterns of nerve dysfunction remains controversial. The aim of the report is to observe and understand the pathology of PIN injury associated with Monteggia fracture-dislocation in children, and to propose the possible indication for the exploration of nerve. Methods: Eight cases, six boys and two girls, with Monteggia fracture-dislocation complicated by PIN injury, managed operatively at the authors Hospital from 2007 to 2008 were retrospectively reviewed. All the patients underwent the attempted closed reduction before they received exploration of PIN, with open reduction and internal fixation or successful closed reduction. Results: The PIN was found to be trapped acutely posterior to the radiocapitellar joint in 4 out of 5 Type III Bado s Monteggia fractures. In the remaining cases, since there were longer time intervals from injury to operation, chronic compressive changes and epineural fibrosis of radial nerve were visualized. After a microsurgical neurolysis performed, the complete recovery in the nerve function was obtained in all the cases during the follow-up. Conclusion: The findings from this study suggest that every case of type III Monteggia fracture-dislocation with decreased or absent function of muscles innervated by PIN and an irreducible radial head in children should be viewed as an indication for immediate surgical exploration of the involved nerve to exclude a potential PIN entrapment. Key words: Monteggia s fracture; Peripheral nerve injuries; Nerve compression syndromes; Pediatrics Chin J Traumatol 2013;16(3): DOI: /cma.j.issn Department of Pediatric Orthopaedics, Xin-Hua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai , China (Li H, Cai QX, Shen PQ, Chen T, Zhang ZM, Zhao L) *Corresponding author: Tel: ext 8470, Fax: , orthzl@126.com Monteggia fracture-dislocation was described by Giovanni Monteggia approximately 200 years ago, as fracture of proximal 1/3 of ulna in association with anterior dislocation of radial head. Radial nerve palsy, which mostly involves in the posterior interosseous nerve (PIN), is a recognized sequela of Monteggia fracture-dislocation. The incidence of radial nerve palsy reported ranged from 3.1% to 31.4% in the literature. 1-4 Fortunately, most of these injuries are neurapraxias and will recover spontaneously after conservative treatment. 5 Whereas, if PIN is wrapped around the neck of radius preventing reduction of radial head, spontaneous recovery cannot be expected. 6,7 However, by now, it remains unclear when the PIN entrapment predisposes to occur along with Monteggia fracturedislocation in children. Thus, the time frame to intervention for nerve injury by Monteggia fracture-dislocation in children remains controversial, especially for early exploration of the involved nerve, which can directly define the morphology of nerve injury. 5,6,8,9 Ruchelsman et al 10 reported a case of an 8-year-old boy with chronic type I Monteggia fracture-dislocation, whose PIN was found to shift posteriorly to radial head and dense capsular cicatrix to encase PIN within proximal radioulnar and radiocapitellar joints. Osamura et al 11 described a case of 6-year-old boy with PIN injury by a chronic Monteggia fracture-dislocation (type III)

2 Chinese Journal of Traumatology 2013;16(3): with delayed neurolysis demonstrating incarceration and rupture of PIN within the radiocapitellar joint. Thus, the fact of limited reports on this issue reminds us of the important value to understand the pathology of involved nerve in Monteggia fracture-dislocation. In this study, we report the pathological findings of PIN injuries associated with Monteggia fracture-dislocation in eight children who underwent surgical exploration of nerve. The aim of the report is to observe and understand the pathology of PIN injury associated with Monteggia fracture-dislocation in children, and to propose the possible indication for the exploration of nerve. METHODS Eight patients, 6 boys and 2 girls, are retrospectively reviewed according to the records from medical charts and the data collected at the clinic in the authors hospital from January 2007 to December The diagnosis of Monteggia fracture-dislocation was confirmed according to the clinical examination and radiographic assessment. All the patients had the complications of PIN, which was diagnosed with the clinical assessment and electromyographic (EMG) test. 12 The major complaint was the inability to dorsally extend the fingers. The radial nerve was explored surgically to detect the pathology of the involved nerve from the distal portion of radial nerve to the branching point of PIN. The age at injury ranged from 2 to 10 years old (average 6.25 years). The time from injury to surgical operation ranged from 6 to 34 days (average 14.1 days). Two boys, with more than 25 days from injury to operation, had chronic Monteggia fracture-dislocation. The right arm was injured in four patients and the left in the remainders. All were closed injuries, including type I of Monteggia fracture-dislocation (Bado classification) in 3 cases and type III in 5 cases. All the patients underwent procedures of closed reduction which failed to obtain radial head reduction before they received exploration of radial nerve with an anterolateral approach. The radial nerve was firstly identified between brachialis and brachioradialis at its emergence from lateral intermuscular septum. Distally, the bifurcation was exposed before PIN was explored to the level of the arcade of Froshe. A posterior approach of ulna was used for the fixation of ulna or ligament reconstruction and extending the anterolateral approach distally for fasciotomy. Postoperatively, a long arm cast with forearm in full supination and elbow maintained in 90 of flexion was applied to all the cases. And all the patients were followed up at regular interval after surgery. RESULTS PIN was found to be entrapped into radiocapitellar joint along with contusion at the bifurcation in four out of five type III fractures (Cases 4, 6-8; Case 6 shown in Figures 1 and 2 ), while compressive changes of PIN, such as epineural swelling or neuratrophy, were also visualized. In case 8, epineural rupture was even found during the exploration procedure. In the other four cases (Cases 1-3 and 5; Case 1 shown in Figures 3 and 4) with relatively long time from injury to operation (more than 12 days), compressive changes and epineural fibrosis of the nerve were visualized along the radial nerve at the bifurcation, PIN or superficial radial nerve. After the exploration procedure, a complete microsurgical neurolysis was performed in all the cases. The nerves were released from the entrapment or encasement by fibrotic tissue and placed with coverage of healthy soft tissues. After the exploration of nerve, two patients (Cases 1 and 3) with chronic Monteggia fracture-dislocation had osteotomy at ulna to correct the ulna deformity and maintained reduction of radial head, and had internal fixation with plate and screws. One of them (Case 3) also had annular ligament reconstruction performed. Another five patients (Cases 4-8) with fresh injury underwent open reduction and internal fixation at ulna with plate and screws in order to obtain anatomic reduction of the ulna and radial head. Among them, one (Case 6) also had ligament reconstruction for the torn annular ligament and another one (Case 4) underwent fasciotomy for fascial compartment syndrome. The last one (Case 2) received another successful closed reduction after exploration of nerve. The patients were followed up for an average of 10 months (from one month to 22 months) postoperatively. The nerve recovery in all cases was complete and the earliest complete recovery happened at one month after neurolysis.

3 Figure 1. Case 6. Preoperative anteroposterior (A) and lateral (B) forearm radiographs after trauma demonstrate type III Monteggia fracture-dislocation with anterolateral dislocation of the radial head and fracture of the ulna. Postoperative anteroposterior (C) and lateral (D) forearm radiographs show the reduction of the radial head, internal fixation at ulna with plate and screws (follow-up of three months). Figure 4. Case 1. Intraoperative radial nerve exploration and neurolysis. Leftward arrow head shows the radial nerve trunk; upward arrow head points the identified radial nerve at the bifurcation, PIN and superficial radial nerve, while microsurgical neurolysis has been performed; downward arrow head demonstrates normal distal part of superficial radial nerve; rightward arrow head denotes PIN. DISCUSSION Figure 2. Case 6. Intraoperative radial nerve exploration and neurolysis. Upward arrow head shows the identified radial nerve at the bifurcation, PIN and superficial radial nerve. Microsurgical neurolysis has been performed; downward arrow head demonstrates compressive changes of PIN, while PIN entrapment has been relieved; rightward arrow head points the normal distal part of superficial radial nerve. Figure 3. Case 1. Preoperative anteroposterior (A) and lateral (B) forearm radiographs after the trauma demonstrate the type I of Monteggia fracture-dislocation with anterior dislocation of the radial head and fracture of the ulna. Postoperative anteroposterior (C) and lateral (D) forearm radiographs show the reduction of the radial head, internal fixation at ulna with plate and screws (followup of two months). PIN palsy following Monteggia fracture-dislocation can be caused by direct trauma, compression at the arcade of Froshe 13, entrapment between radius and ulna 7, stretching around radial neck during closed reduction, and tardy palsy caused by scarring from an unreduced radial head 14. Fortunately, most PIN injuries associated with closed Monteggia fracture-dislocation of all types are neurapraxias that will resolve spontaneously after successful closed reduction. Monteggia fractures successfully reduced without PIN function return by 8 weeks or EMG changes by 6 weeks were previously thought to be the main indication for PIN exploration. 6,8 Our findings suggest that PIN entrapment in the radiocapillar joint often occurs in type III Monteggia fracture-dislocation in children with irreducible radial heads and PIN deficit. Therefore, we suggest that such cases should also be considered a clear surgical indication for acute exploration of the radial nerve and its branch to PIN in Monteggia fracture-dislocation in children. Despite limited number of the cases reported, our results still suggest the possible relation of the type of Monteggia fracture-dislocation with the morphology of PIN injury in children, such as nerve entrapment. Actually, by now, few reports have been focused on the issue in children. Bado s classification was well established clinically on the basis of injury mechanism and pattern of radial head dislocation, subdividing Monteggia fracture-dislocation into true Monteggia fracture-dislo-

4 Chinese Journal of Traumatology 2013;16(3): cation (type I-IV) and equivalent lesions. 15 In the pediatric population, types I and III Monteggia fracture-dislocation are the most common. 16 Generally, an adduction force causes the type III lesion. A simultaneous pronation of the forearm results in an anteriolateral dislocation of the radial head, while a supination of the forearm leads to a posteriolateral dislocation of the radial head. 17 Therefore, varus angulation of elbow and lateral dislocation of radial head between the superficial and deep branch of radial nerve allows PIN to slide posteriorly to the radial head. 6 At the attempt to reduce the dislocated radial head, PIN predisposes to be shifted beneath the radial head and interposed into the radiocapitellar joint. This lassoing effect causes a neuropraxia and an inability to reduce the radial head by closed means, which had been confirmed in cadaveric dissections. In this situation, an aggressive reduction of radial head might have caused rupture of PIN between the radial head and capitellum humeri. 6,7 In the literature 18,19, failure to reduce a dislocated radial head may be due to other interposed structures, such as capsule, annular ligament, and osteocartilaginous fragments resulted from intra-articular fracture. However, in these patients with irreducible radial head who had PIN deficit simultaneously, the PIN entrapment should be suspected firstly until proved otherwise. Indeed, we did not find the interposed capsule and annular ligament, or intra-articular fracture by open treatment. PIN entrapment injury resulting from Monteggia fracture-dislocation with lateral dislocation of the radial head is also reported in the literature. 6,11 Therefore, if type III Monteggia fracture-dislocation happens in the pediatric patient along with neurological deficit because of PIN injury and the radial head is irreducible, the entrapment of PIN should be considered and the exploration of PIN may be the optimal treatment of choice. Osteotomy at ulna in these patients (Cases 1, 3-8) is performed in order to correct the ulna deformity, obtain and maintain anatomic reduction of the ulna radial head and radial head. 20,21 However, of course, we did not mean that irreducible radial head dislocation necessitates operative ulna fixation in addition to the obviously required open exploration of the radiocapitellar joint. Moreover, in those patients without PIN entrapped (Cases 1-3 and 5), compressive changes and epineural fibrosis of the nerve, which may result from local soft tissue injury or hematoma, were visualized along the radial nerve at the bifurcation, PIN or superficial radial nerve during the exploration procedures. Therefore, micro neurolysis was performed to release the encasement of nerve by fibrotic tissue, which we thought to be beneficial to the nerve recovery. This study may have two limitations: 1) small number of cases in the report, 2) lack of observation of controls. In the present report, we just focused on the poorly known complication of PIN entrapped in a radiocapitellar joint after Monteggia fracture-dislocation and provided related cases to attract pediatric orthopeadic surgeons attention. Although without exactly reviewing the clinical cases in our hospital, based on our own clinical experience, the actual rate of pediatric Monteggia fracture-dislocation requiring nerve exploration may be very low, which may lower surgeons guard for the occurrence of wrapped PIN. In addition, we do not think that it is beneficial for patients with PIN deficit and irreducible radial head to observe rather than explore the nerve. Therefore, we could not provide the relevant controls. In spite of these limitations, the present report is important and helpful to remind surgeon of reconsidering the indication of nerve exploration. Clinically, the assessment of nerve dysfunction in Monteggia fracture-dislocation according to Seddon and Sunderland s classification of nerve injuries is to accurately classify how severe the nerve injuries may be, and to predict if these injuries will recovery spontaneously without need for early exploration. 22 However, without direct exploration of nerve, the grade of nerve injuries could only be deduced based upon the indirect evidence from repeated physical exams and EMG studies, and it could not be differentiated whether the involved nerve is entrapped or stretched. On the other hand, the physical exam, which might detect variable clinical features, such as motor or sensory dysfunction or weakness, could only indicate the location rather than morphology of nerve injury. 12,13 Similarly, EMG studies in the fourth week after injury are helpful in localizing the site of nerve injury, and in estimating the extent of injury. However, to ensure the need for surgical exploration, repeated EMG evaluation is supposed to be undertaken in eight weeks after injury. Moreover, one major disadvantage of EMG studies is that the status of the connective tissue component of the nerve cannot be assessed without direct exploration. 5,23 Therefore, present exams after Monteggia fracture-dislocation could not help surgeon to determine the necessity of early explo-

5 ration of nerve in the acute setting, and another simple exam means should be developed to detect the pathoanatomy of PIN injury rapidly. It is proposed that the condition of type III pediatric Monteggia fracture-dislocation with PIN injury and an irreducible radial head should be highly suspected of PIN entrapment and considered as the potential case for immediate surgical exploration of nerve. REFERENCES 1. Bruce HE, Harvey JP, Wilson JC Jr. Monteggia fractures. J Bone Joint Surg Am 1974;56(8): Stein F, Grabias SL, Deffer PA. Nerve injuries complicating Monteggia lesions. J Bone Joint Surg Am 1971;53(7): Boyd HB, Boals JC. The Monteggia lesion. A review of 159 cases. Clin Orthop Relat Res 1969;(66): Smith FM. Monteggia fractures: an analysis of 25 consecutive fresh injuries. Surg Gynecol Obstet 1947;85(5): Ristic S, Strauch RJ, Rosenwasser MP. The assessment and treatment of nerve dysfunction after trauma around the elbow. Clin Orthop Relat Res 2000(370): Spar I. A neurologic complication following Monteggia fracture. Clin Orthop Relat Res 1977;(122): Morris AH. Irreducible Monteggia lesion with radial-nerve entrapment. A case report. J Bone Joint Surg Am 1974;56(8): Hirachi K, Kato H, Minami A, et al. Clinical features and management of traumatic posterior interosseous nerve palsy. J Hand Surg Br 1998;23(3): Young C, Hudson A, Richards R. Operative treatment of palsy of the posterior interosseous nerve of the forearm. J Bone Joint Surg Am 1990;72(8): Ruchelsman DE, Pasqualetto M, Price AE, et al. Persistent posterior interosseous nerve palsy associated with a chronic type I Monteggia fracture-dislocation in a child: a case report and review of the literature. Hand (NY) 2009;4(2): Osamura N, Ikeda K, Hagiwara N, et al. Posterior interosseous nerve injury complicating ulnar osteotomy for a missed Monteggia fracture. Scand J Plast Reconstr Surg Hand Surg 2004; 38(6): Hirayama T, Takemitsu Y. Isolated paralysis of the descending branch of the posterior interosseous nerve. Report of a case. J Bone Joint Surg Am 1988;70(9): Spinner M. The arcade of Frohse and its relationship to posterior interosseous nerve paralysis. J Bone Joint Surg Br 1968; 50(4): Holst-Nielsen F, Jensen V. Tardy posterior interosseous nerve palsy as a result of an unreduced radial head dislocation in Monteggia fractures: a report of two cases. J Hand Surg Am 1984; 9(4): Bado JL. The Monteggia lesion. Clin Orthop Relat Res 1967;(50): Olney BW, Menelaus MB. Monteggia and equivalent lesions in childhood. J Pediatr Orthop 1989;9(2): Mullick S. The lateral Monteggia fracture. J Bone Joint Surg Am 1977;59(4): Reckling FW. Unstable fracture-dislocations of the forearm (Monteggia and Galeazzi lesions). J Bone Joint Surg Am 1982; 64(6): Tompkins DG. The anterior Monteggia fracture: observations on etiology and treatment. J Bone Joint Surg Am 1971;53(6): Best TN. Management of old unreduced Monteggia fracture dislocations of the elbow in children. J Pediatr Orthop 1994; 14(2): Stoll TM, Willis RB, Paterson DC. Treatment of the missed Monteggia fracture in the child. J Bone Joint Surg Br 1992; 74(3): Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951;74(4): Oh SJ. Electromyographic studies in peripheral nerve injuries. South Med J 1976;69(2): (Received June 6, 2012) Edited by SONG Shuang-ming