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Congenital pseudarthrosis of the ulna
CONGENITAL
PSEUDARTHROSIS
OF THE ULNA
J. C. Y. CHENG, L. K. HUNG andR. C. BUNDOC
From The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong Congenital ulnar pseudarthrosis is a very rare condition. Two cases are reported in addition to 36 already reported in the English literature. One of the cases reported had a “one-hone forearm” procedure done, with a satisfactory result after 6 years. The second case had a free vascularized fibula graft procedure with restoration of the bony alignment and union after 8 months of follow-up. Journal of Hand Surgery (British and European, 1994) 19B: 238-243
Congenital pseudarthrosis of the ulna is a rare clinical entity. Its close relation to neurofibromatosis is well documented. Diagnosis of the condition is clinical and radiographic. Treatment is aimed towards achieving good function and preventing progressive deformity. Reports of the results of treatment usually lack longterm follow-up and treatment options remain varied; no single procedure has been shown to be better than the others. Two cases of congenital pseudarthrosis of the ulna are reported with a review of the literature.
CASE 2
A 3-month-old girl presented with a deformity of the right forearm showing prominent radial bowing. There was no neurovascular deficit and the arms were used equally. Elbow motion was full and stable. Forearm rotation was also full. Cafe-au-lait spots were evident on the forearm and trunk. Radiographs of the forearm revealed a gap in the middle third of the ulna. The bone ends were tapering and sclerotic. The radial head was still well aligned with the capitellum (Fig 2a). The patient was treated conservatively with a long arm functional brace for 6 months, and at the age of 9 months early evidence of radial head instability was noticed clinically. Radiologically near complete resorption of the distal ulna was found. The patient underwent an operative resection of the ulna pseudarthrosis of 6 cm with preservation of the proximal ulna and distal ulnar epiphysis. The gap was replaced by a free vascularized fibular graft of the same length taken from the opposite leg. Direct end-to-end anastomoses were done between the peroneal artery and ulnar artery and between the peroneal vein and the basilic vein. The graft was fixed by a wire loop proximally and a longitudinal intramedullary Kirschner wire (Fig 2b). The donor site was stabilized by a bony synostosis created between the distal fibula and adjacent tibia using Gilbert’s technique (Gilbert, 1979). Post-operatively, the graft was protected by an external plaster cast for 8 weeks followed by a functional brace for another 10 weeks. The intramedullary fixation was removed at 8 weeks when early union was detected radiologically. At follow-up 8 months after the surgery, sound union was noted at the anastomosis site (Fig 2c) and the child started to move satisfactorily with wrist flexion of 60”, extension 30” and forearm pronation/supination of 60”/50”.
CASE 1
A male child was first seen at the age of 4 years with a deformity of the left forearm. This showed excessive radial bowing with marked prominence over the lateral aspect of the elbow. Elbow flexion was limited to 40” and had 10” of hyperextension, similar to the right. Forearm rotation was likewise limited to 20” and 30” of supination and pronation respectively. The radial head was palpably dislocated over the anterolateral aspect of the left elbow. There was mild medial instability of 20”. There was no tenderness. Hand and wrist function were good, and no neurovascular deficit was evident. There were cafe-au-lait spots all over the body. Radiographs of the forearm showed a gap at the junction of the distal and middle third of the ulna with tapered sclerotic bone ends. The distal ulnar fragment was markedly hypoplastic. The normal bow of the radius was exaggerated and its head was dislocated anterolaterally (Fig la). The patient underwent a “one-bone” forearm operation at the age of 4 years. The distal ulnar segment and the radius at the same level were resected, and the proximal ulna was apposed to the distal radial segment and fixed with an intra-medullary pin similar to the technique of Straub (1965). Autogenous cancellous bone grafts from the iliac crest were placed around the junction. A long arm cast and a functional brace were worn postoperatively until union was completed at 14 weeks (Fig lb). 6 years later, at the age of 10, the patient has good hand function despite 2 cm shortening of the forearm, which was in a neutral position (Fig lc). Elbow power was comparable with the other side, and there was a full range of flexion and extension. There was medial instability on a valgus stress test of the elbow of 30” but no loss of ulnar nerve function.
DISCUSSION
Congenital pseudarthrosis of the forearm is a rare condition. So far only 37 cases have been reported in the English literature (Ali and Hooper, 1982; Allieu et al, 1981; Atar and Lehman, 1991; Baldwin and Weiner, 1974; Bayne, 1985; Bell, 1989; Cobb, 1968; Fernandez, 1986; Gregg et al, 1982; Herring and Roach, 1985; Kameyama and Ogawa, 1990; Manske, 1979; Masihuz-Zaman, 1977; Masterson et al, 1993; Ostrowski 238
ULNAR PSEUDARTHROSIS
Fig 1
Patient patient
1. (a) Congenital ulnar pseudarthrosis in a four-year-old boy with a markedly hypoplastic distal ulnar fragment. treated with a one-bone forearm procedure. (c) Good fusion and a functional foreann 6 years after surgery.
(b) Same
240
Fig 2
THE JOURNAL OF HAND SURGERY VOL. 19B No. 2 APRIL 1994
(a) and (b) For legend please see page 241.
et al, 1985; Richin et al, 1976; Sprague and Brown, 1974; Straub, 1965; Williamson et al, 1989). The epidemiology is uncertain. Our two cases represent the incidence in a population of around 1 million over a lo-year period. There appears to be no racial or demographic predisposition. The radius and the ulna are equally affected ( 13 and 17 patients respectively out of 36 cases). The radius and the ulna were both affected in only six cases (Bayne, 1985; Manske, 1979; Richin et al, 1976). None has presented with bilateral forearm lesions, and pseudarthrosis of the lower limbs has not been reported in combination with a forearm lesion. The junction of the distal and middle third of the forearm bones is affected in 76% of cases. As previously reported by Bell (1989), there is a very close association with neurofibromatosis, and cafe-au-lait spots are present in 69% of cases. Cases which do not present with symptoms of neurofibromatosis may have a positive family history of the disease. The usual presenting sign is excessive radial bowing in the forearm. All cases had a normal obstetrical history with uncomplicated delivery. Pain is an infrequent complaint, and usually related to an episode of trauma. Tenderness is normally not present except when preceded
by trauma. There were no neurovascular deficits in any of the reported cases and a soft tissue mass was only seen in one (Sprague and Brown, 1974). Patients may present shortly after birth, or later, when the deformity is recognized in infancy or childhood. Only 27% (10/36) of cases presented shortly after birth and the rest were seen as deformities brought about by trivial episodes of trauma. For this reason the condition has been named “infantile pseudarthrosis of the forearm” (Bell, 1989). Diagnosis is often arrived at clinically in correlation with its distinct radiographic presentations. Forearm radiographs usually show an obvious gap in the affected forearm bone. The bone ends are usually narrowed with varying degrees of sclerosis and the medullary cavity is obliterated. Depending on the duration of the pseudarthrosis, the unaffected bone of the forearm shows progressive angulation with the concavity facing the lesion, and the distal fragment appears hypoplastic. The epiphysis of the distal fragment is always present although it may not be clearly seen radiographically. In a small number of patients, the condition presents as a cystic lesion in the meta-diaphyseal junction seen as an incidental X-ray findings. Fractures are usually seen running transversely across the cystic lesion and in
ULNAR PSEUDARTHROSIS
Fig 2
Patient 2. (a) Congenital ulnar pseudarthrosis in a 3-monthold baby girl showing the same hypoplasia of the distal ulnar fragment. (b) Free vascularized fibular graft fixed by wire loop and intramedullary Kirschner wire at 9-months of age. (c) Good incorporation of the vascularized graft 8 months after surgery.
all cases they progress to the classical radiographic appearance. Other clinical conditions that can present with the same radiographic findings are congenital longitudinal deficiencies of the radius and/or the ulna. These are distinguished by the presence of hypoplastic forearms and underdeveloped digits. On radiographs, the physes are absent in longitudinal deficiency of the forearm. Certain tumours also present with similar radiographic pictures, especially when pressure necrosis is seen on the forearm bone. These benign or malignant conditions can be very well differentiated by their clinical presentations. Non-union in forearm fractures may present with the same radiographic picture but this problem is almost non-existent in children, even if left untreated. Treatment of congenital forearm pseudarthrosis present challenge,s. Attention should be given to associated system problems which can be life-threatening. Knowing that a large number of patients present with neurofib-
241
romatosis, the patients should be screened for scoliosis which can be present in 60% of such patients. The patients should also be closely observed for the development of tumours of ectodermal origin, such as astrocytoma, optic glioma and Wilm’s tumour (Crawford, 1990). It should also be borne in mind that most patients have impaired wound healing. Treatment of the forearm deformity is aimed at stabilizing the extremity, preventing shortening and deformities, and improving hand function. Treatment modalities include conservative management by means of functional bracing, especially when the problem is detected early or when other conditions prevent surgery. This will prevent the progressive deformity that may be induced in the pliable and growing bone of children who are starting to crawl. However, in most cases bracing alone fails to produce union. Of greater concern is the fact that in all cases presenting with ulnar pseudarthrosis, lateral dislocation of the radial head almost always occurs if the condition is left untreated, as shown in our first case. The radial head has been reported to dislocate as early as 1 year of age (Bell, 1989). From this observation it may be safe to infer that surgical intervention should be initiated once the patient’s condition can allow it. In one such case where the radial head did not dislocate, early osteoarthritis developed between the capitello-radial joint in a 21-year-old patient (Fernandez, 1986). This condition was thought to be secondary to the pressure brought about by the constraints of the ulnar tether. The main concern, however, is to achieve union of the pseudarthrosis. Numerous techniques of autogenous bone grafting have been tried by different authors with varying degrees of success. Of all bone grafting techniques reported, the vascularized fibular graft has yielded a good union rate in reported cases (Allieu et al, 1981; Bell, 1989; Masterson et al, 1993; Williamson et al, 1989). Its advantage lies in its capacity to bridge long gaps where other forms of bone grafting can easily fail. Free vascularized fibular grafts probably work best in patients in whom the radial head is not dislocated. Once the latter has dislocated, other procedures should be considered. Even in successfully united ulnar pseudarthrosis, the symbiotic growth of the forearm is affected. The radius continues to outgrow the ulna and will eventually lead to problems. The effect on the normal growth of the donor lower extremities in children after taking out the fibula is another concern. Atar and Lehman (1991) have reported persistence of pseudarthrosis after treatment with a vascularized fibular graft with subsequent resorption of the graft. Our first case presented with a large bone defect for which a vascularized fibular graft might be appropriate. However, the distal fragment was so hypoplastic that fixation of the graft would have posed technical difficulties. Trimming of the sclerosed ends of the ulnar fragment may not leave sufficient bone stock for fixing the fibular graft while still maintaining the integrity of
242
THE JOURNAL OF HAND SURGERY VOL. 19B No. 2 APRIL 1994
the distal ulnar epiphysis and an intact distal radioulnar joint. At the same time the radial head of the patient was already dislocated anterolaterally which had caused marked limitation of elbow function and instability. Even if union were achieved with a free vascularized graft the elbow function would not be significantly improved, and there would have been a persistent growth discrepancy and progressive problem at the elbow. Therefore we selected the “one-bone forearm” procedure which was described by Straub (1965) and LloydRoberts (1973; Fig 3). This is a shorter and easier procedure which does not impose great surgical risks, preserves length and has good union rate. However, it has the disadvantage of preventing rotation of the forearm. In our patient we achieved good union after 14 weeks while the patient was maintained in a functional brace. After 6 years the patient has a good functional range of motion with the forearm in a neutral position. There is persistent medial instability on valgus stress of the elbow. The forearm has shortening of 2 cm but hand function is good. The patient seems to be uninhibited by these limitations.
Our second case presents with a very similar clinical picture except that she was diagnosed early and normal anatomy around the elbow joint was preserved. A vascularized fibular graft was chosen in this young child, good union at a follow-up of 8 months. A longer term follow-up is necessary to monitor the growth of the ulna, and any gross discrepancy between the radius and ulna may have to be corrected by lengthening procedures. In conclusion, two cases of congenital pseudarthrosis of the ulna are reported in addition to 36 cases of forearm pseudarthrosis reported in literature to date. A review of the literature shows that the surgical management of congenital ulnar pseudarthrosis remains a therapeutic problem. Depending on the variable factors present at diagnosis, free vascularized bone grafting has been shown to give good results in a number of cases. A “one-bone forearm” procedure is a good alternative once the radial head has dislocated and when there is insufficient distal bone stock to hold a graft. It gives a stable forearm, good hand function and acceptable forearm shortening. n
Fig 3
One-bone forearm operation (Illustration). (a) Distal ulnar pseudarthrosis. (b) Osteotomy of the radius and the ulna at the same level with resection of the distal ulnar and proximal radial segments. (c) Alignment of the distal radius and proximal ulna with an intramedullary pin fixation, and autogenous cancellous bone grafting.
ULNAR
References ALI,
243
PSEUDARTHROSIS
M. S. and HOOPER, G. (1982). Congenital pseudarthrosis of the ulna due to neurofibromatosis. Journal of Bone and Joint Surgery, 64B: 5: 600-602. ALLIEU, Y., GOMIS; R., YOSHIMURA, M., DIMEGLIO, A. and BONNEL, F. (1981). Congenital pseudarthrosis of the forearm-two cases treated by free vascularized fibular graft. Journal of Hand Surgery, 6: 5: 475-481. ATAR, D. and LEHMAN, W. B. (1991). Ilizarov technique in treatment of congenital hand anomalies: Two case reports. Clinical Orthopaedics and Related Research, 273: 268-274. BALDWIN, D. M. and WEINER, D. S. (1974). Congenital bowing and intraosseous neurofibroma of the ulna: A case report. Journal of Bone Joint Surgery, 56A: 4: 803-807. BAYNE, L. G. (1985). Congenital pseudarthrosis of the forearm. Hand Clinics, 1: 3: 457-465. BELL, D. F. (1989). Congenital forearm pseudarthrosis: Report of six cases and review of literature. Journal of Pediatric Orthopedics, 9: 4: 438-443. CRAWFORD, A. H. Neurofibromatosis. In Love11 and Winter (Ed.): Pediatric Orthopuedics, 3rd Edn. Philadelphia, Lippincott, 1990, 175. COBB, N. (1968). Neurofibromatosis and pseudarthrosis of the ulna: A case report. Journal of Bone and Joint Surgery, 50B: 1: 146-149. FERNANDEZ, G. N. (1986). Pseudarthrosis of the ulna and osteoarthritis of the elbow: A case report. Journal of Bone and Joint Surgery, 68B: 4: 574-576. GILBERT, A. (1979). Vascularized transfer of the fibular shaft. International Journal of Microsurgery, 1: 100-102. GREGG, P. J., PRICE, B. A.; ELLIS, H. A. and STEVENS, J. (1982). Pseudarthrosis of the radius associated with neurofibromatosis: A case report. Clinical Orthopaedics and Related Research, 171: 175-179. HERRING, J. A. and ROACH, J. W. (1985). Congenital pseudarthrosis of the radius. Journal of Pediatric Orthopedics, 5: 3: 367-369. KAMEYAMA, 0. and OGAWA; R. (1990). Pseudarthrosis of the radius associ-
ated with neurofibromatosis: Report of a case and review of literature. Journal of Pediatric Orthopedics, 10: 1: 128-131. LLOYD-ROBERTS, G. C. (1973). Treatment of defects of the ulna in children by establishing cross-union with the radius. Journal of Bone and Joint Surgery, 55B: 2: 327-330. MANSKE, P. R. (1979). Forearm pseudarthrosis-neurofibromatosis: Case report. Clinical Orthopaedics and Related Research, 139: 125-127. MASIHUZ-ZAMAN, M. B. (1977). Pseudarthrosis of the radius associated with neurofibromatosis: A case report. Journal of Bone and Joint Surgery, 59A: 7: 977-978. MASTERSON, E., EARLEY, M. J. and STEPHENS, M. M. (1993). Congenital pseudarthrosis of the ulna treated by free vascularized fibular graft: A case report and review of methods of treatment. Journal of Hand Surgery, 18B: 3: 285-288. OSTROWSKI, D. M., EILERT, R. E. and WALDSTEIN, G. (1985). Congenital pseudarthrosis of the ulna: A report of two cases and a review of literature. Journal of Pediatric Orthopedics, 5: 4: 463-467. RICHIN, P. F., KRANIK, A., VAN-HERPE, L. and SUFFECOOL, S. L. (1976). Congenital pseudarthrosis of both bones of the forearm: A case report. Journal of Bone and Joint Surgery, 58A: 7: 1032-1033. SPRAGUE, B. L. and BROWN, G. A. (1974). Congenital pseudarthrosis of the radius. Journal of Bone and Joint Surgery, 56A: 1: 191-194. STRAUB, L. R. (1965). Congenital absence of the ulna. American Journal of Surgery, 109: 300-305. WILLIAMSON, D. M., COPELAND, S. A. and LANDI, A. (1989). Pseudarthrosis of the radius treated by free vascularized bone graft. journal of Hand Surgery, 14B: 2: 221-225.
Accepted after revision: 7 October 1993 Dr Jack C. Y. Cheng, Pediatric Orthopaedic Traumatology, The Chinese University of Hong Hong Kong. Q 1994 The British
Society
for Surgery
Service, Department of Orthopaedics Kong, Prince of Wales Hospital, Shatin,
of the Hand
& NT
PSEUDARTHROSIS
OF THE ULNA
J. C. Y. CHENG, L. K. HUNG andR. C. BUNDOC
From The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong Congenital ulnar pseudarthrosis is a very rare condition. Two cases are reported in addition to 36 already reported in the English literature. One of the cases reported had a “one-hone forearm” procedure done, with a satisfactory result after 6 years. The second case had a free vascularized fibula graft procedure with restoration of the bony alignment and union after 8 months of follow-up. Journal of Hand Surgery (British and European, 1994) 19B: 238-243
Congenital pseudarthrosis of the ulna is a rare clinical entity. Its close relation to neurofibromatosis is well documented. Diagnosis of the condition is clinical and radiographic. Treatment is aimed towards achieving good function and preventing progressive deformity. Reports of the results of treatment usually lack longterm follow-up and treatment options remain varied; no single procedure has been shown to be better than the others. Two cases of congenital pseudarthrosis of the ulna are reported with a review of the literature.
CASE 2
A 3-month-old girl presented with a deformity of the right forearm showing prominent radial bowing. There was no neurovascular deficit and the arms were used equally. Elbow motion was full and stable. Forearm rotation was also full. Cafe-au-lait spots were evident on the forearm and trunk. Radiographs of the forearm revealed a gap in the middle third of the ulna. The bone ends were tapering and sclerotic. The radial head was still well aligned with the capitellum (Fig 2a). The patient was treated conservatively with a long arm functional brace for 6 months, and at the age of 9 months early evidence of radial head instability was noticed clinically. Radiologically near complete resorption of the distal ulna was found. The patient underwent an operative resection of the ulna pseudarthrosis of 6 cm with preservation of the proximal ulna and distal ulnar epiphysis. The gap was replaced by a free vascularized fibular graft of the same length taken from the opposite leg. Direct end-to-end anastomoses were done between the peroneal artery and ulnar artery and between the peroneal vein and the basilic vein. The graft was fixed by a wire loop proximally and a longitudinal intramedullary Kirschner wire (Fig 2b). The donor site was stabilized by a bony synostosis created between the distal fibula and adjacent tibia using Gilbert’s technique (Gilbert, 1979). Post-operatively, the graft was protected by an external plaster cast for 8 weeks followed by a functional brace for another 10 weeks. The intramedullary fixation was removed at 8 weeks when early union was detected radiologically. At follow-up 8 months after the surgery, sound union was noted at the anastomosis site (Fig 2c) and the child started to move satisfactorily with wrist flexion of 60”, extension 30” and forearm pronation/supination of 60”/50”.
CASE 1
A male child was first seen at the age of 4 years with a deformity of the left forearm. This showed excessive radial bowing with marked prominence over the lateral aspect of the elbow. Elbow flexion was limited to 40” and had 10” of hyperextension, similar to the right. Forearm rotation was likewise limited to 20” and 30” of supination and pronation respectively. The radial head was palpably dislocated over the anterolateral aspect of the left elbow. There was mild medial instability of 20”. There was no tenderness. Hand and wrist function were good, and no neurovascular deficit was evident. There were cafe-au-lait spots all over the body. Radiographs of the forearm showed a gap at the junction of the distal and middle third of the ulna with tapered sclerotic bone ends. The distal ulnar fragment was markedly hypoplastic. The normal bow of the radius was exaggerated and its head was dislocated anterolaterally (Fig la). The patient underwent a “one-bone” forearm operation at the age of 4 years. The distal ulnar segment and the radius at the same level were resected, and the proximal ulna was apposed to the distal radial segment and fixed with an intra-medullary pin similar to the technique of Straub (1965). Autogenous cancellous bone grafts from the iliac crest were placed around the junction. A long arm cast and a functional brace were worn postoperatively until union was completed at 14 weeks (Fig lb). 6 years later, at the age of 10, the patient has good hand function despite 2 cm shortening of the forearm, which was in a neutral position (Fig lc). Elbow power was comparable with the other side, and there was a full range of flexion and extension. There was medial instability on a valgus stress test of the elbow of 30” but no loss of ulnar nerve function.
DISCUSSION
Congenital pseudarthrosis of the forearm is a rare condition. So far only 37 cases have been reported in the English literature (Ali and Hooper, 1982; Allieu et al, 1981; Atar and Lehman, 1991; Baldwin and Weiner, 1974; Bayne, 1985; Bell, 1989; Cobb, 1968; Fernandez, 1986; Gregg et al, 1982; Herring and Roach, 1985; Kameyama and Ogawa, 1990; Manske, 1979; Masihuz-Zaman, 1977; Masterson et al, 1993; Ostrowski 238
ULNAR PSEUDARTHROSIS
Fig 1
Patient patient
1. (a) Congenital ulnar pseudarthrosis in a four-year-old boy with a markedly hypoplastic distal ulnar fragment. treated with a one-bone forearm procedure. (c) Good fusion and a functional foreann 6 years after surgery.
(b) Same
240
Fig 2
THE JOURNAL OF HAND SURGERY VOL. 19B No. 2 APRIL 1994
(a) and (b) For legend please see page 241.
et al, 1985; Richin et al, 1976; Sprague and Brown, 1974; Straub, 1965; Williamson et al, 1989). The epidemiology is uncertain. Our two cases represent the incidence in a population of around 1 million over a lo-year period. There appears to be no racial or demographic predisposition. The radius and the ulna are equally affected ( 13 and 17 patients respectively out of 36 cases). The radius and the ulna were both affected in only six cases (Bayne, 1985; Manske, 1979; Richin et al, 1976). None has presented with bilateral forearm lesions, and pseudarthrosis of the lower limbs has not been reported in combination with a forearm lesion. The junction of the distal and middle third of the forearm bones is affected in 76% of cases. As previously reported by Bell (1989), there is a very close association with neurofibromatosis, and cafe-au-lait spots are present in 69% of cases. Cases which do not present with symptoms of neurofibromatosis may have a positive family history of the disease. The usual presenting sign is excessive radial bowing in the forearm. All cases had a normal obstetrical history with uncomplicated delivery. Pain is an infrequent complaint, and usually related to an episode of trauma. Tenderness is normally not present except when preceded
by trauma. There were no neurovascular deficits in any of the reported cases and a soft tissue mass was only seen in one (Sprague and Brown, 1974). Patients may present shortly after birth, or later, when the deformity is recognized in infancy or childhood. Only 27% (10/36) of cases presented shortly after birth and the rest were seen as deformities brought about by trivial episodes of trauma. For this reason the condition has been named “infantile pseudarthrosis of the forearm” (Bell, 1989). Diagnosis is often arrived at clinically in correlation with its distinct radiographic presentations. Forearm radiographs usually show an obvious gap in the affected forearm bone. The bone ends are usually narrowed with varying degrees of sclerosis and the medullary cavity is obliterated. Depending on the duration of the pseudarthrosis, the unaffected bone of the forearm shows progressive angulation with the concavity facing the lesion, and the distal fragment appears hypoplastic. The epiphysis of the distal fragment is always present although it may not be clearly seen radiographically. In a small number of patients, the condition presents as a cystic lesion in the meta-diaphyseal junction seen as an incidental X-ray findings. Fractures are usually seen running transversely across the cystic lesion and in
ULNAR PSEUDARTHROSIS
Fig 2
Patient 2. (a) Congenital ulnar pseudarthrosis in a 3-monthold baby girl showing the same hypoplasia of the distal ulnar fragment. (b) Free vascularized fibular graft fixed by wire loop and intramedullary Kirschner wire at 9-months of age. (c) Good incorporation of the vascularized graft 8 months after surgery.
all cases they progress to the classical radiographic appearance. Other clinical conditions that can present with the same radiographic findings are congenital longitudinal deficiencies of the radius and/or the ulna. These are distinguished by the presence of hypoplastic forearms and underdeveloped digits. On radiographs, the physes are absent in longitudinal deficiency of the forearm. Certain tumours also present with similar radiographic pictures, especially when pressure necrosis is seen on the forearm bone. These benign or malignant conditions can be very well differentiated by their clinical presentations. Non-union in forearm fractures may present with the same radiographic picture but this problem is almost non-existent in children, even if left untreated. Treatment of congenital forearm pseudarthrosis present challenge,s. Attention should be given to associated system problems which can be life-threatening. Knowing that a large number of patients present with neurofib-
241
romatosis, the patients should be screened for scoliosis which can be present in 60% of such patients. The patients should also be closely observed for the development of tumours of ectodermal origin, such as astrocytoma, optic glioma and Wilm’s tumour (Crawford, 1990). It should also be borne in mind that most patients have impaired wound healing. Treatment of the forearm deformity is aimed at stabilizing the extremity, preventing shortening and deformities, and improving hand function. Treatment modalities include conservative management by means of functional bracing, especially when the problem is detected early or when other conditions prevent surgery. This will prevent the progressive deformity that may be induced in the pliable and growing bone of children who are starting to crawl. However, in most cases bracing alone fails to produce union. Of greater concern is the fact that in all cases presenting with ulnar pseudarthrosis, lateral dislocation of the radial head almost always occurs if the condition is left untreated, as shown in our first case. The radial head has been reported to dislocate as early as 1 year of age (Bell, 1989). From this observation it may be safe to infer that surgical intervention should be initiated once the patient’s condition can allow it. In one such case where the radial head did not dislocate, early osteoarthritis developed between the capitello-radial joint in a 21-year-old patient (Fernandez, 1986). This condition was thought to be secondary to the pressure brought about by the constraints of the ulnar tether. The main concern, however, is to achieve union of the pseudarthrosis. Numerous techniques of autogenous bone grafting have been tried by different authors with varying degrees of success. Of all bone grafting techniques reported, the vascularized fibular graft has yielded a good union rate in reported cases (Allieu et al, 1981; Bell, 1989; Masterson et al, 1993; Williamson et al, 1989). Its advantage lies in its capacity to bridge long gaps where other forms of bone grafting can easily fail. Free vascularized fibular grafts probably work best in patients in whom the radial head is not dislocated. Once the latter has dislocated, other procedures should be considered. Even in successfully united ulnar pseudarthrosis, the symbiotic growth of the forearm is affected. The radius continues to outgrow the ulna and will eventually lead to problems. The effect on the normal growth of the donor lower extremities in children after taking out the fibula is another concern. Atar and Lehman (1991) have reported persistence of pseudarthrosis after treatment with a vascularized fibular graft with subsequent resorption of the graft. Our first case presented with a large bone defect for which a vascularized fibular graft might be appropriate. However, the distal fragment was so hypoplastic that fixation of the graft would have posed technical difficulties. Trimming of the sclerosed ends of the ulnar fragment may not leave sufficient bone stock for fixing the fibular graft while still maintaining the integrity of
242
THE JOURNAL OF HAND SURGERY VOL. 19B No. 2 APRIL 1994
the distal ulnar epiphysis and an intact distal radioulnar joint. At the same time the radial head of the patient was already dislocated anterolaterally which had caused marked limitation of elbow function and instability. Even if union were achieved with a free vascularized graft the elbow function would not be significantly improved, and there would have been a persistent growth discrepancy and progressive problem at the elbow. Therefore we selected the “one-bone forearm” procedure which was described by Straub (1965) and LloydRoberts (1973; Fig 3). This is a shorter and easier procedure which does not impose great surgical risks, preserves length and has good union rate. However, it has the disadvantage of preventing rotation of the forearm. In our patient we achieved good union after 14 weeks while the patient was maintained in a functional brace. After 6 years the patient has a good functional range of motion with the forearm in a neutral position. There is persistent medial instability on valgus stress of the elbow. The forearm has shortening of 2 cm but hand function is good. The patient seems to be uninhibited by these limitations.
Our second case presents with a very similar clinical picture except that she was diagnosed early and normal anatomy around the elbow joint was preserved. A vascularized fibular graft was chosen in this young child, good union at a follow-up of 8 months. A longer term follow-up is necessary to monitor the growth of the ulna, and any gross discrepancy between the radius and ulna may have to be corrected by lengthening procedures. In conclusion, two cases of congenital pseudarthrosis of the ulna are reported in addition to 36 cases of forearm pseudarthrosis reported in literature to date. A review of the literature shows that the surgical management of congenital ulnar pseudarthrosis remains a therapeutic problem. Depending on the variable factors present at diagnosis, free vascularized bone grafting has been shown to give good results in a number of cases. A “one-bone forearm” procedure is a good alternative once the radial head has dislocated and when there is insufficient distal bone stock to hold a graft. It gives a stable forearm, good hand function and acceptable forearm shortening. n
Fig 3
One-bone forearm operation (Illustration). (a) Distal ulnar pseudarthrosis. (b) Osteotomy of the radius and the ulna at the same level with resection of the distal ulnar and proximal radial segments. (c) Alignment of the distal radius and proximal ulna with an intramedullary pin fixation, and autogenous cancellous bone grafting.
ULNAR
References ALI,
243
PSEUDARTHROSIS
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Accepted after revision: 7 October 1993 Dr Jack C. Y. Cheng, Pediatric Orthopaedic Traumatology, The Chinese University of Hong Hong Kong. Q 1994 The British
Society
for Surgery
Service, Department of Orthopaedics Kong, Prince of Wales Hospital, Shatin,
of the Hand
& NT