Traumatic bowing of the forearm bones in roller machine injuries

Injury, Int. J. Care Injured (2004) 35, 1202—1206 CASE REPORT Traumatic bowing of the forearm bones in roller machine injuries Ramesh K. Sen, Jitender K. Jain, O.N. Nagi* Department of Orthopaedic Surgery, Post Graduate Institute of Medical Education and Research, Chandigarh 160023, India Accepted 12 October 2003 KEYWORDS Forearm bones; Bowing; Adults; Mature skeleton; Roller injuries Summary Slow bending forces created by rollers of rotating machines and acting on forearm bones can result in traumatic bowing even in adults. Four patients having this peculiar injury pattern in industrial accidents have been reported in this paper. Three of these had concomitant fractures of ipsilateral humerus. There were problems in appropriate reduction of the deformity due to the presence of associated overlying soft tissue injury. The literature has also been reviewed for this injury and 13 reports defining the injury profile, problems in realigning forearm bones and their subsequent maintenance have been described. The eventual outcome of such machine injuries has not been good due to persistence of some degrees of bowing and associated restriction of forearm rotation. ß 2003 Elsevier Ltd. All rights reserved. Introduction Case reports Acute plastic deformation of long bones is rare in adults with few case reports published in literature.1—3,7,8,11—18 While in children, the mechanism for such an injury is usually a fall on outstretched hands,4 in adults the injury is usually entrapment on moving rollers in machines.1,2,8,11—18 We report four such cases where industrial accidents led to variable amount of forearm bowing along with associated injuries to the ipsilateral upper limb. All the known reports previously published in the English literature have been analysed to define the management problems and eventual outcomes in this peculiar injury pattern. Case 1 *Corresponding author. Present address: House No. 1027, 24-B, Chandigarh 160023, India. Tel.: þ91-172-728851; fax: þ91-172-721133. E-mail address: [email protected] (O.N. Nagi). A 25-year-old male was working on a slow moving roller machine, when a bracelet on his right forearm entangled around one of the bolts and the limb was subsequently dragged over to the roller. The second bolt pressed the volar aspect of proximal forearm and third bolt pressed against humerus. The machine was stopped after about a minute, following which the patient could remove his limb from the roller. On clinical examination, there was skin avulsion over right upper limb at two sites. The right forearm showed bowing deformity with painful restriction of pronation—supination. There was an associated ipsilateral fracture of the humeral shaft which was further complicated by a high radial nerve palsy. Radiograph of the forearm confirmed dorsal bowing of forearm bones (Fig. 1a). 0020–1383/$ — see front matter ß 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2003.10.024 Traumatic bowing of the forearm bones in roller machine injuries 1203 Figure 1 Radiographs showing: (a) dorsal bowing forearm bones; (b) humerus fracture after plate osteosynthesis; (c) humerus after removal of plate; (d) residual forearm bowing. The patient was operated upon for wound debridement and humerus fracture fixation using a dynamic compression plate (Fig. 1b). The radial nerve was found to be in continuity. The forearm bowing could not be corrected by manipulation and the overlying skin was considered too damaged to consider an open reduction. After debridement of superficial necrotic tissues, skin grafting was performed and the limb was supported in arm pouch sling. After a month, the overlying skin recovered and the radial nerve also regained its function, but due to persistent bowing deformity, there was restriction of rotational movements and the patient also had inability to completely extend his fingers. As the patient was already back to his job, he again met with an accident and suffered a traumatic amputation of second, third and fourth fingers of the opposite hand. As his right hand only was functioning, fearing more disability, he did not opt for any more intervention for the forearm bowing except for removal of the humeral plate after 1 year. At 4 years post-injury evaluation (Fig. 1c and d), he still had forearm movements restricted to 508 pronation and 208 supination. His right hand function was near normal with the wrist kept in flexion, but he was unable to make a complete fist in extension. Case 2 A 17-year-old male labourer sustained trauma on a mixer machine in a pharmaceutical factory. While trying to retrieve a bag entrapped on a rolling machine, his right forearm also got pulled on and twisted around the roller. He could extricate his limb only after he stopped the machine by forcing the conveyer belt to slip off the roller which took about 30 s. On clinical examination, the patient had volar bowing deformity of right forearm, a grade III-A open fracture of ipsilateral humerus along with high radial nerve palsy. Radiographs confirmed volar bowing of radius to be at middle—distal third junction and a comminuted fracture of the midshaft humerus with loss of a butterfly fragment. After debridement of the wound, the fractured humerus was stabilised on an external fixator (EF). The radial nerve was in continuity but contused at the fracture site. An attempt was made to reduce the deformity by closed manipulation of the forearm bowing by keeping it on a padded support. The limb was immobilised in a below elbow POP cast with the forearm placed in neutral rotation for 8 weeks, when cortico-cancellous bone grafting was performed at humerus fracture site with the EF 1204 retained. After a further 6 weeks, the humeral fracture showed evidence of radiological union but there was persistence of some degree of radius bowing. At that time, the patient had terminal 208 loss of elbow extension with forearm movements limited to supination of 608 and pronation of 208. The patient was placed in a humeral cast for a further 4 weeks, but subsequently he was lost to follow-up. Case 3 An 18-year-old male got his hand entrapped in the roller of a printing machine. His right forearm and subsequently his arm were also bent over it, till the machine was stopped. His hand was crushed and traumatically amputated at wrist level. On examination, there was significant dorsal bowing deformity in forearm bones and fracture of the ipsilateral humerus. After emergency disarticulation of the crushed hand at radiocarpal level, the forearm stump was debrided and the wound closed. The attempted manipulation proved inadequate in reducing the forearm bowing. Further, the forearm could not be immobilised to maintain the achieved reduction as a result of the amputation at the wrist. The humerus fracture was however stabilised on a POP U-slab. At 10 weeks follow-up, the forearm movements were restricted between 108 pronation and 508 supination and the radiograph at that time revealed relatively less bowing of the forearm bones. Case 4 A 16-year-old male met with an industrial accident when the cuff of his unbuttoned shirt sleeve got caught in a roller machine, pulling his right upper limb on to it. The limb could be taken out only after the machine was stopped in about 30 s. Clinical examination revealed a closed humeral fracture along with dorsal bowing deformity of the forearm. The radiograph showed this to be a non-comminuted fracture of the humeral diaphysis and increased posterior bow of both forearm bones. Under general anaesthesia, closed manipulation was done to straighten the forearm bones, along with closed reduction of the fractured humerus and the limb was immobilised in an above elbow POP cast. After removal of the POP at 8 weeks, physiotherapy was started to regain elbow and forearm movements. At 24 weeks follow-up, the patient had regained a full range of elbow movements but forearm movements were restricted to about 508 of supination to 408 of pronation and radiographs showed persistence of bowing deformity. R.K. Sen et al. Discussion Chamay studied the effect of compressive longitudinal forces in causing bowing deformity in dog bones.5 Using the experimental data, he demonstrated that the limit of an elastic response was not the fracture but a defined zone of plastic deformation. It was further observed that the duration of the deforming force was critical for the plastic behaviour of bones and the curvature was produced if the deforming force was removed just before the occurrence of fracture. With maturation of bone its elastic properties change. Currey and Butler6 observed that the average modulus of elasticity for the cortical bone was 9.0 GPa in the age group less than 5 years compared with an average value of 12 GPa for a bone in the group 5—17 years of age and was an average of 14.8 GPa for bone in a group with more than 18 years of age. Thus, plastic deformation of the forearm bones is a fairly well-known entity in children and the usual cause is by a fall on an outstretched hand.4 There have been only two reports of such a deformity occurring in adults bones with this mode of injury.3,7 In comparison, in 11 other case reports and in four patients of the present series, the injury has occurred in accidents. During working on rotating machines, either the hand, shirt or a bangle around wrist of the victim has been reported to be entangled onto the conveyer belt or roller hooks, thus creating a bending pull to the forearm. The deforming force has also been continuous and even for a few minutes.1,8,11 It has also been observed15 that in adults bones, bowing may result from gradual application of a shearing force and maintenance of this injuring force for a considerable length of time. One characteristic feature in all these reports has been the typical age distribution. With increasing maturation of bone, greater mineralisation stiffens the collagen and hydroxyapatite complex, thereby decreasing the amount of deformity1 it is likely to tolerate until failure. Except for a case reported by Babhulkar et al.,2 where the patient was aged 30 years, all other 16 patients suffering forearm bowing, including four of the present series, were less than 25 years of age. All cases except one,8 suffering such skeletal bowing in industrial accidents have been males and this may be due to predominant male involvement in the kind of occupations where this injury is likely. The right—left distribution of this injury is also very characteristic with 11 of the 17 patients having forearm bowing on the right side. The typical clinical features reported in such injuries have been pain, diffuse swelling, gross deformity, tenderness and restriction in the rotational movements of the Traumatic bowing of the forearm bones in roller machine injuries forearm. The associated swelling of both bones however can sometime mask the actual bowing and as there is usually no frank mobility, the real diagnosis can even be missed.12,13 The diagnosis can also be missed if a single bone is bowed and the other bone is either fractured or subluxated at the radioulnar joint.7 In acute clinical presentations, restriction of forearm rotation, especially pronation, has been a uniform observation. In suspected cases, complete radiographic evaluation consists of anteroposterior, lateral and sometimes oblique films to confirm and grade the bowing deformity. In the forearm, if a single bone shows bowing deformity, the other bone is either fractured or subluxated/ dislocated at the radioulnar joints.3,7 Comparison with films taken of contralateral forearm in the same plane is likely to be useful. Increase in radiotracer activity throughout the length of bone is also confirmatory though rarely required.1,10 In none of these case reports has there been the presence of any systemic or endocrinological disease affecting the quality of bones, i.e. all these have been purely the result of trauma. The deformity spectrum in forearm bowing of the mature skeleton is typical. In 11 of the reported 17 patients including the present 4, both the bones of the forearm were bowed. In three patients, the radius alone had the bowing deformity and two of these had an associated ulnar fracture.11,14 In two of the three patients suffering isolated ulnar bowing, the mechanism of injury was a fall on outstretched hand3,7 and the radioulnar joint was either subluxed or dislocated. In the third case of isolated ulnar bowing, the injury occurred when the hand was caught in a tyre rim and the radius was fractured.18 In two patients,8,17 there was a fracture at a different level in addition to bowing deformity of radius. The presence of simultaneous injury to the humerus has been reported only once11 in the literature. This occurred in all four cases of the present series and is likely to be the result of proximal continuation of the injury mechanism. It is also likely that at humerus level a rotational element is added to the bending force, resulting in butterfly comminution as was seen in two of these patients. There has been a single report of medial nerve paraesthesia occurring in forearm bowing.17 None of the present cases showed it, though two had high radial nerve involvement which can be attributed to the associated humerus fracture. Reduction difficulty can be anticipated in this pattern of deformity. Sanders and Heckman14 have proposed the principles of reduction in paediatric forearm bowing, i.e. there should be adequate 1205 anaesthesia, reduction of the most deformed bone should be undertaken first, placing the apex of the deformity over a fulcrum made of a firm sandbag or a rolled towel; applying pressure over the proximal and distal ends; applying the force gradually and keeping this for several minutes; treating the individual components of deformities in other planes separately and in a similar fashion and finally; treating any existing fracture in the remaining bone by whatever method that would have been selected had a plastic deformation not occurred. King modified the method and used the surgeon’s knee as the fulcrum point and applied corrective force over 5—8 min.9 He also suggested that approximately 85% of the deformity should be corrected before applying the cast. If the deformity is not correctable then it has also been proposed that drilling the apex of the deformed bone may be done through a small incision to fracture the bone and to effect the reduction. Care must be taken to avoid complete breaking of the bowed bone, which is a well reported complication.8 Osteoclasis to get realignment has also been proposed.15 Gordon et al. have performed a closing wedge osteotomy of the ulna in a patient with ulnar bowing.7 In overall analysis, manipulation to reduce the deformity was successful in 9 of the total 17 cases (including 4 of present series). Reduction was not attempted at all for various reasons in three patients. In most of these patients, an above elbow POP cast has been used for a period of 6—8 weeks for maintenance of reduction. There have been reports of the use of Rush pins15 or Ender’s intramedullary nailing18 to maintain the correction. Plate fixation along with corrective osteotomy at an interval of 4—6 weeks has also been reported.7,17 Only five patients had return of full rotational movements of forearm. In four other patients, even though the reduction was said to be achieved, there persisted some restriction usually of pronation. Among three documented failed reductions, late osteotomy brought back full rotational movement in two.7,17 The limitation of forearm rotation usually persists as a result of diminished cortical remodelling in adults compared to children.19 In conclusion, forearm bowing occurring as a result of injuries from machine rollers should be defined as an occupational hazard with need for early and appropriate diagnosis. Association of overlying soft tissue or hand injury or ipsilateral humerus fracture, though uncommon, adds significant problems in deformity correction. Careful manipulation is required to realign forearm bones and at a late stage osteotomy may have to be performed to regain appropriate limb function. 1206 References 1. Anderson IF. Plastic bowing of the forearm on more mature skeleton. Aus N Z J Surg 1994;64(2):132—4. 2. Babhulkar SS, Pande KC, Babhulkar S. Bowing injury of forearm in an adult. Injury 1995;26:277—8. 3. Bajaj HN, Joseph B. Traumatic bowing of the ulna in an adult. Clin Radiol 1989;40:651. 4. Borden S. Roentgen recognition of acute plastic bowing of the forearm in children. Am J Roentgenol 1975;125:524—30. 5. Chamay A. Mechanical and morphological aspects of experimental overload and fatigue in bone. J Biomech 1969;3: 263—70. 6. Currey JD, Butler G. the mechanical properties of bone tissue in children. J Bone Joint Surg Am 1975;57:810—4. 7. Gordon L, Beaton W, Thomas T, Mulbry LW. Acute plastic deformation of the ulna on a skeletally mature individual. J Hand Surg A 1991;16:451—3. 8. Greene WB. 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