Eur J Pediatr (1992) 151 : 543-545
European Journal of
Pediatrics
9 Springer-Verlag1992
Hypertension associated with skeletal traction in children H.A.Heij, S.Ekkelkamp, and A.Vos Department of Pediatric Surgery, Free University Hospital, P. O.Box 7057, NL-1007 MB Amsterdam, The Netherlands Received July 22, 1991 / Accepted after revision November 18, 1991
Abstract. Since traction-associated hypertension seems to be a relatively unknown p h e n o m e n o n , a survey was done of its incidence in children treated with skeletal traction for fractures and orthopaedic diseases. The correlation with hypercalcaemia, a possible aetiological factor, was also explored. Blood pressure was recorded three times a day with an automatic oscillometric unit during the stay in the hospital. Serum calcium, creatinine and total protein concentrations were measured once a week. Patients with pre-existing diseases or renal trauma were excluded. Arterial hypertension (systolic and/or diastolic) was found in 31/50 children (62%). In almost half of these the rise in systolic blood pressure was 10 m m H g or m o r e above the 95th percentile. Hypertension occurred in most cases within the first 3 weeks of treatment; in 7 children it developed after 3 or m o r e weeks of traction. All children became normotensive within i week after discontinuation of traction. Clinical symptoms were rare: two children complained of headache. In no instance had traction to be discontinued before the planned date because of hypertension. In the hypertensive group were m o r e preschool children and m o r e humeral fractures as c o m p a r e d to the normotensive group (n = 19). Hypercalcaemia occurred in 11 children and was equally distributed in hypertensive and in normotensive children. It is concluded that arterial hypertension is a frequent finding in children in traction, but its clinical relevance is uncertain. Hypercalcaemia is not a rare finding in immobilized children, but probably plays no causative role in traction-related hypertension.
Key words: Arterial hypertension - Skeletal traction Fractures - Children - Hypercalcaemia
Introduction Arterial hypertension has been reported in children treated with skeletal traction for femoral, humeral and forearm fractures or congenital dislocation of the hip [4, 9, 10, 13, 15]. Severe symptoms, even hypertensive heOffprint requests to: H. A. Heij
phropathy and encephalopathy, have been described [2, 10]. In all instances, blood pressures returned to normal values after discontinuation of traction. Hypertension has also been recorded in children who underwent leglengthening procedures [12, 19, 20], operative correction of flexion-contracture [5, 1t] and kyphoscoliosis [8, 14]. Not only skeletal traction, but also plaster immobilisation has been associated with hypertension [16]. Although m a n y of the cited observations concern case-reports, from several larger series the incidence of hypertension associated with traction and immobilisation can be estim a t e d t o b e 5 4 % - 6 8 % [4, 16]. After leg lengthening hypertension was found in 20 out of 24 children (80%) [20]. The aetiology of traction-associated hypertension in children is not known. Several explanations have been offered: hypercalcaemia [1, 3, 6, 10], increased sympathetic tone because of traction on nerves [17, 18, 20] or on pelvic soft tissue [16]. With the aim of exploring the incidence of hypertension in children in traction and the clinical relevance in terms of signs and symptoms, we recorded blood pressure of children above 1 year who were treated with skeletal traction. Also, the serum calcium levels were measured weekly, in order to test the hypercalcaemia hypothesis.
Patients and methods Between 1 January 1987 and 31 December 1989 blood pressures were recorded three times daily (while awake) in 50 consecutive children over 1 year of age who were admitted to the Department of Paediatric Surgery for skeletal traction treatment. Diagnosis and other details of the patients are listed in Table 1. Continuous traction was maintained in all children throughout the observation period. Blood pressure recordings were in almost all instances done with the Dynamap oscillometric unit. Two recordings were made at one time and the average was noted. The length of the cuff was approximately 2/3 of the length of the upper arm. All children received adequate analgesics during the initial phase and diazepam during the 1st week for muscle relaxation. Reference values were taken from a Dutch epidemiology survey [7]. Hypertension was defined as systolic and/or diastolic blood pressure above 95th percentile for age and sex on at least three occasions. Other injuries were treated as indicated, but multitrauma patients were not included in this study.
544 Table 1. Details of 50 patients treated by skeletal traction
Number F/M
Table 2. Correlation between hypertension and hypercalcaemia
Hypertensiona
Normotension
Total
31
19
50
Hypercalcaemia
5
6
11
7/12
16/34
Normocalcaemia
26
13
39
Diagnosis (hypercalcaemic children) Fractured femur 4 Fractured humerus 1 Fractured leg 0 Other 0
2 2 1 1
6 3 1 1
(13)
9/22 (4/9)
Age (years) 0-5 6-10 11-15
13 12 6
(6) (4) (3)
3 10 6
16 22 12
Diagnosis Fractured femur Fractured leg Fractured humerus Other diagnoses
17 1 12 1
(6) (6) (1)
i0 3 2 4
27 4 14 5
Between brackets the number of children with blood pressure elevation > 10 mmHg above the 95th percentile
Immediately after admission, a urine specimen was analysed for the presence of glucose, protein and microscopic abnormalities. Once a week, serum levels of calcium, creatinine and total protein were measured, usually in capillary blood samples. Patients with abnormal findings on renal ultrasound and/or urinanalysis were excluded from the study. All observations were collected as stated until the patient was discharged from hospital.
Hypertension
Normotension
Total
Table 3. Incidence of hypercalcaemia in various age groups
Hyper calcaemia Age (years) 0-5 6-10 11-16 Total
Normocalcaemia
Total
1 7 3
15 15 9
16 22 12
11
39
50
calcaemia. Serum protein and creatinine levels remained normal in all children. Serum calcium levels normalised in all children after discontinuation of traction.
Results Discussion
Arterial hypertension according to the outlined criteria was found in 31/50 children (62%). Details of hypertensive and normotensive patients are given in Table 1. In the hypertensive group there were relatively more preschool children and patients with a fractured humerus than in the normotensive group. Hypertension occurred in the 1st week in 9 patients, in the 2nd week in 9, in the 3rd week in 6, and later on in 7. In the majority of hypertensive patients blood pressures fluctuated. Blood pressures became normal in all patients within 1 week after discontinuation of traction. Only 2 patients with hypertension complained of headache. No ophthalmological or otorhinological abnormalities were found in these patients. Moderate and severe rises in blood pressure (as defined by readings 1 0 m m H g or more above the 95th percentile) were found in 13 of these children: 9 boys and 4 girls. The distribution of age and diagnosis in these children was not different from the other hypertensive children (Table 1). Hypercalcaemia, defined as serum levels above 2.75 retool/l, was found in 11 out of 50 children (22%), with equal frequency in the hypertensive and the normotensive group (Table 2). Hypercalcaemia was relatively more frequent in the age group 6-10 years as compared with the other age groups (Table 3). Hypercalcaemia never occurred during the 1st week after admission. In two patients it developed during the 2nd week, in three during the 3rd week, and in six during the 4th week or later. No clinical signs or symptoms could be attributed to hyper-
Hypertension associated with skeletal traction or immobilization has received little attention so far. In order to define the incidence and clinical significance of arterial hypertension associated with traction in children, we conducted this survey. Furthermore, we looked into the aetiology by estimating serum calcium levels since hypercalcaemia has been proposed as a cause of traction-associated hypertension [1, 3, 6, 10]. Three hypotheses with regard to the aetiology of this hypertension have been proposed. Immobilisation causes hypercalcaemia, which can lead to renal micro-angiopathy and activation of the renin-angiotension-aldosterone system [1, 3, 6, 10]. However, normal serum calcium levels have been reported in children with traction associated hypertension [4, 9, 11, 13, 16]. Another objection against this hypothesis is the fact that traction associated hypertension can occur very early after leg lengthening, before hypercalcaemia develops [17, 18]. A second hypothesis infers traction on nerves with concomitant increase of sympathetic tone [17, 18, 20]. Against this explanation is the finding of hypertension in children who are immobilised in plaster casts without traction [16]. Thirdly, stretching of pelvic soft tissues may increase sympathetic activity in the splanchnic area with adrenal catecholamine release. This might, together with increased afferent sciatic nerve activity and hypovolaemia induce reflectory spasm of renal arteries with excessive or inappropriate plasma renin activity levels. Elevated
545 catecholamine levels were reported in one of three patients [16]. Normal values were found by others [4, 13]. Elevated plasma renin levels were reported by some [11, 13] but not by others [4]. The definition of arterial hypertension in children is complicated by the many variables, like age, weight, sex and race. The reference values obtained in a large epidemiological survey in the Netherlands have been used in this study. Hypertension was found on repeated occasions in 62% of our patients while in traction. It occurred relatively more often in preschool children and in patients with a fractured humerus. Most patients developed hypertension during the first 3 weeks of traction. A rise in systolic blood pressure of more than 1 0 m m H g above the 95th percentile occurred in 13 children, almost half of the hypertensive patients. Age, sex and diagnosis distribution was not different compared to the other hypertensive cases. Complications were not noted and traction treatment was maintained in all patients. Blood pressure became normal in all instances after termination of traction. Our findings do not indicate that hypercalcaemia plays a major role in the pathogenesis of traction induced hypertension. It is possible that traction-associated hypertension has a multifactorial aetiology. Early hypertension might be caused by catecholamine release, but late hypertension could be related to hypercalcaemia. This hypothesis should be tested in a larger series of patients. The clinical relevance of traction-associated hypertension and hypercalcaemia is uncertain at this stage. Routine measurement of blood pressure in children in traction can probably be limited to weekly recordings, unless symptoms of hypertension occur. Similarly, serum calcium estimations in immobilized children should be done only when indicated by complications.
Acknowledgement. Blood pressure recordings were performed with a Dynamap machine, kindly put at our disposal by Messrs. Portanje, Utrecht, Netherlands
References 1. Berliner BC, Shenkers IR, Weinstock MS (1972) Hypercalcemia associated with hypertension due to prolonged immobilization. Pediatrics 49 : 92-96 2. Dodd K, Graubarth H, Rapaport S (1950) Hypercalcemia nephropathy and encephalopathy following immobilization. Pediatrics 6 : 124-130
3. Earll JM, Kurtzman NA, Moser RH (1966) Hypercatcemia and hypertension. Ann Int Med 64: 378-381 4. Hamdan JA, Taler YA, Ahmed MS (1984) Traction-induced Hypertension in Children. Clin Orthop 185 : 87-89 5. Harandi BA, Zahir S (1974) Severe Hypertension following Correction of Flexion Contracture of the Knee. J Bone Joint Surg 56 [Am] : 1733-1734 6. Heath H, Earll JM, Schaaf M, Piechocki JT, Li TK (1972) Serum ionized calcium during bed rest in fracture patients and normal men. Metabolism 21 : 633-640 7. Hofman A, Valkenburg HA (1980) Distribution and determinants of blood pressure in free living children. In: Kesteloot H, Joossens JV (eds) Epidemiology of arterial blood pressure. M. Nijhof, London, pp 99-117 8. Kessler G, Bischoff K, Web L (1982) Hypertensive Kreislaufver~inderungen bei Skolioseoperationen wfihrnd und nach der Distraktionsphase. Intensivmed Prax 5 : 1-8 9. Linshaw MA, Stapleton FB, Gruskin AB, Baluarte HJ, Harbin GL (1979) Traction-related hypertension in children. J Pediatrics 95 : 994-996 10. Little JA, Dean AE, Chapman M (1982) Immobilization Hypercakcemia. South Med J 75 : 502 11. Mardini MK, Mikati MA, Lifeso R (1981) Hypertensive encephalopathy: rare complication after orthopedic manipulation. Am J Dis Child 136 : 1092-1094 12. Miller A, Rosam MA (1983) Hypertensive encephalopathy as a complication of femoral lengthening. Can Med Assoc J 124 : 296-297 13. Milner LS, Thomson PD, Levin SE (1983) Traction-induced hypertension in a child. S Afr Med J 63 : 757 14. Streitz W, Brown JC, Bonnett C (1977) Anterior fibular strut grafting in the treatment of kyphosis. Clin Orthop 128 : 140148 15. Talab YA, Hamdan J, Ahmed M (1982) Orthopaedic Causes of Hypertension in Pediatric Patients. J Bone Joint Surg 64 [Am] : 291-292 16. Turner MC, Ruley EJ, Bnckley KM, Strife CF (1979) Blood pressure elevation in children with orthopedic immobilization. J Pediatrics 95 : 989-992 17. Whitehill R, Hakala W (1976) The hypertension of femoral lengthening: a canine experimental model. Surg Forum 26: 525-526 18. Whitehill R, Hakala MW (1978) Arterial hypertension induced by femoral lengthening, a canine model. J Bone Joint Surg 60 [Am] : 815-819 19. Wilk LH, Badgley CE (1963) Hypertension, another complication of the leg-lengthening procedure. J Bone Joint Surg 45 [Am] : 1263-1268 20. Yosipovitch ZH, Palti Y (1967) Alterations in blood pressure during leg-lengthening, a clinical and experimental investigation. J Bone Joint Surg 49 [Am] : 1352-1358
European Journal of
Pediatrics
9 Springer-Verlag1992
Hypertension associated with skeletal traction in children H.A.Heij, S.Ekkelkamp, and A.Vos Department of Pediatric Surgery, Free University Hospital, P. O.Box 7057, NL-1007 MB Amsterdam, The Netherlands Received July 22, 1991 / Accepted after revision November 18, 1991
Abstract. Since traction-associated hypertension seems to be a relatively unknown p h e n o m e n o n , a survey was done of its incidence in children treated with skeletal traction for fractures and orthopaedic diseases. The correlation with hypercalcaemia, a possible aetiological factor, was also explored. Blood pressure was recorded three times a day with an automatic oscillometric unit during the stay in the hospital. Serum calcium, creatinine and total protein concentrations were measured once a week. Patients with pre-existing diseases or renal trauma were excluded. Arterial hypertension (systolic and/or diastolic) was found in 31/50 children (62%). In almost half of these the rise in systolic blood pressure was 10 m m H g or m o r e above the 95th percentile. Hypertension occurred in most cases within the first 3 weeks of treatment; in 7 children it developed after 3 or m o r e weeks of traction. All children became normotensive within i week after discontinuation of traction. Clinical symptoms were rare: two children complained of headache. In no instance had traction to be discontinued before the planned date because of hypertension. In the hypertensive group were m o r e preschool children and m o r e humeral fractures as c o m p a r e d to the normotensive group (n = 19). Hypercalcaemia occurred in 11 children and was equally distributed in hypertensive and in normotensive children. It is concluded that arterial hypertension is a frequent finding in children in traction, but its clinical relevance is uncertain. Hypercalcaemia is not a rare finding in immobilized children, but probably plays no causative role in traction-related hypertension.
Key words: Arterial hypertension - Skeletal traction Fractures - Children - Hypercalcaemia
Introduction Arterial hypertension has been reported in children treated with skeletal traction for femoral, humeral and forearm fractures or congenital dislocation of the hip [4, 9, 10, 13, 15]. Severe symptoms, even hypertensive heOffprint requests to: H. A. Heij
phropathy and encephalopathy, have been described [2, 10]. In all instances, blood pressures returned to normal values after discontinuation of traction. Hypertension has also been recorded in children who underwent leglengthening procedures [12, 19, 20], operative correction of flexion-contracture [5, 1t] and kyphoscoliosis [8, 14]. Not only skeletal traction, but also plaster immobilisation has been associated with hypertension [16]. Although m a n y of the cited observations concern case-reports, from several larger series the incidence of hypertension associated with traction and immobilisation can be estim a t e d t o b e 5 4 % - 6 8 % [4, 16]. After leg lengthening hypertension was found in 20 out of 24 children (80%) [20]. The aetiology of traction-associated hypertension in children is not known. Several explanations have been offered: hypercalcaemia [1, 3, 6, 10], increased sympathetic tone because of traction on nerves [17, 18, 20] or on pelvic soft tissue [16]. With the aim of exploring the incidence of hypertension in children in traction and the clinical relevance in terms of signs and symptoms, we recorded blood pressure of children above 1 year who were treated with skeletal traction. Also, the serum calcium levels were measured weekly, in order to test the hypercalcaemia hypothesis.
Patients and methods Between 1 January 1987 and 31 December 1989 blood pressures were recorded three times daily (while awake) in 50 consecutive children over 1 year of age who were admitted to the Department of Paediatric Surgery for skeletal traction treatment. Diagnosis and other details of the patients are listed in Table 1. Continuous traction was maintained in all children throughout the observation period. Blood pressure recordings were in almost all instances done with the Dynamap oscillometric unit. Two recordings were made at one time and the average was noted. The length of the cuff was approximately 2/3 of the length of the upper arm. All children received adequate analgesics during the initial phase and diazepam during the 1st week for muscle relaxation. Reference values were taken from a Dutch epidemiology survey [7]. Hypertension was defined as systolic and/or diastolic blood pressure above 95th percentile for age and sex on at least three occasions. Other injuries were treated as indicated, but multitrauma patients were not included in this study.
544 Table 1. Details of 50 patients treated by skeletal traction
Number F/M
Table 2. Correlation between hypertension and hypercalcaemia
Hypertensiona
Normotension
Total
31
19
50
Hypercalcaemia
5
6
11
7/12
16/34
Normocalcaemia
26
13
39
Diagnosis (hypercalcaemic children) Fractured femur 4 Fractured humerus 1 Fractured leg 0 Other 0
2 2 1 1
6 3 1 1
(13)
9/22 (4/9)
Age (years) 0-5 6-10 11-15
13 12 6
(6) (4) (3)
3 10 6
16 22 12
Diagnosis Fractured femur Fractured leg Fractured humerus Other diagnoses
17 1 12 1
(6) (6) (1)
i0 3 2 4
27 4 14 5
Between brackets the number of children with blood pressure elevation > 10 mmHg above the 95th percentile
Immediately after admission, a urine specimen was analysed for the presence of glucose, protein and microscopic abnormalities. Once a week, serum levels of calcium, creatinine and total protein were measured, usually in capillary blood samples. Patients with abnormal findings on renal ultrasound and/or urinanalysis were excluded from the study. All observations were collected as stated until the patient was discharged from hospital.
Hypertension
Normotension
Total
Table 3. Incidence of hypercalcaemia in various age groups
Hyper calcaemia Age (years) 0-5 6-10 11-16 Total
Normocalcaemia
Total
1 7 3
15 15 9
16 22 12
11
39
50
calcaemia. Serum protein and creatinine levels remained normal in all children. Serum calcium levels normalised in all children after discontinuation of traction.
Results Discussion
Arterial hypertension according to the outlined criteria was found in 31/50 children (62%). Details of hypertensive and normotensive patients are given in Table 1. In the hypertensive group there were relatively more preschool children and patients with a fractured humerus than in the normotensive group. Hypertension occurred in the 1st week in 9 patients, in the 2nd week in 9, in the 3rd week in 6, and later on in 7. In the majority of hypertensive patients blood pressures fluctuated. Blood pressures became normal in all patients within 1 week after discontinuation of traction. Only 2 patients with hypertension complained of headache. No ophthalmological or otorhinological abnormalities were found in these patients. Moderate and severe rises in blood pressure (as defined by readings 1 0 m m H g or more above the 95th percentile) were found in 13 of these children: 9 boys and 4 girls. The distribution of age and diagnosis in these children was not different from the other hypertensive children (Table 1). Hypercalcaemia, defined as serum levels above 2.75 retool/l, was found in 11 out of 50 children (22%), with equal frequency in the hypertensive and the normotensive group (Table 2). Hypercalcaemia was relatively more frequent in the age group 6-10 years as compared with the other age groups (Table 3). Hypercalcaemia never occurred during the 1st week after admission. In two patients it developed during the 2nd week, in three during the 3rd week, and in six during the 4th week or later. No clinical signs or symptoms could be attributed to hyper-
Hypertension associated with skeletal traction or immobilization has received little attention so far. In order to define the incidence and clinical significance of arterial hypertension associated with traction in children, we conducted this survey. Furthermore, we looked into the aetiology by estimating serum calcium levels since hypercalcaemia has been proposed as a cause of traction-associated hypertension [1, 3, 6, 10]. Three hypotheses with regard to the aetiology of this hypertension have been proposed. Immobilisation causes hypercalcaemia, which can lead to renal micro-angiopathy and activation of the renin-angiotension-aldosterone system [1, 3, 6, 10]. However, normal serum calcium levels have been reported in children with traction associated hypertension [4, 9, 11, 13, 16]. Another objection against this hypothesis is the fact that traction associated hypertension can occur very early after leg lengthening, before hypercalcaemia develops [17, 18]. A second hypothesis infers traction on nerves with concomitant increase of sympathetic tone [17, 18, 20]. Against this explanation is the finding of hypertension in children who are immobilised in plaster casts without traction [16]. Thirdly, stretching of pelvic soft tissues may increase sympathetic activity in the splanchnic area with adrenal catecholamine release. This might, together with increased afferent sciatic nerve activity and hypovolaemia induce reflectory spasm of renal arteries with excessive or inappropriate plasma renin activity levels. Elevated
545 catecholamine levels were reported in one of three patients [16]. Normal values were found by others [4, 13]. Elevated plasma renin levels were reported by some [11, 13] but not by others [4]. The definition of arterial hypertension in children is complicated by the many variables, like age, weight, sex and race. The reference values obtained in a large epidemiological survey in the Netherlands have been used in this study. Hypertension was found on repeated occasions in 62% of our patients while in traction. It occurred relatively more often in preschool children and in patients with a fractured humerus. Most patients developed hypertension during the first 3 weeks of traction. A rise in systolic blood pressure of more than 1 0 m m H g above the 95th percentile occurred in 13 children, almost half of the hypertensive patients. Age, sex and diagnosis distribution was not different compared to the other hypertensive cases. Complications were not noted and traction treatment was maintained in all patients. Blood pressure became normal in all instances after termination of traction. Our findings do not indicate that hypercalcaemia plays a major role in the pathogenesis of traction induced hypertension. It is possible that traction-associated hypertension has a multifactorial aetiology. Early hypertension might be caused by catecholamine release, but late hypertension could be related to hypercalcaemia. This hypothesis should be tested in a larger series of patients. The clinical relevance of traction-associated hypertension and hypercalcaemia is uncertain at this stage. Routine measurement of blood pressure in children in traction can probably be limited to weekly recordings, unless symptoms of hypertension occur. Similarly, serum calcium estimations in immobilized children should be done only when indicated by complications.
Acknowledgement. Blood pressure recordings were performed with a Dynamap machine, kindly put at our disposal by Messrs. Portanje, Utrecht, Netherlands
References 1. Berliner BC, Shenkers IR, Weinstock MS (1972) Hypercalcemia associated with hypertension due to prolonged immobilization. Pediatrics 49 : 92-96 2. Dodd K, Graubarth H, Rapaport S (1950) Hypercalcemia nephropathy and encephalopathy following immobilization. Pediatrics 6 : 124-130
3. Earll JM, Kurtzman NA, Moser RH (1966) Hypercatcemia and hypertension. Ann Int Med 64: 378-381 4. Hamdan JA, Taler YA, Ahmed MS (1984) Traction-induced Hypertension in Children. Clin Orthop 185 : 87-89 5. Harandi BA, Zahir S (1974) Severe Hypertension following Correction of Flexion Contracture of the Knee. J Bone Joint Surg 56 [Am] : 1733-1734 6. Heath H, Earll JM, Schaaf M, Piechocki JT, Li TK (1972) Serum ionized calcium during bed rest in fracture patients and normal men. Metabolism 21 : 633-640 7. Hofman A, Valkenburg HA (1980) Distribution and determinants of blood pressure in free living children. In: Kesteloot H, Joossens JV (eds) Epidemiology of arterial blood pressure. M. Nijhof, London, pp 99-117 8. Kessler G, Bischoff K, Web L (1982) Hypertensive Kreislaufver~inderungen bei Skolioseoperationen wfihrnd und nach der Distraktionsphase. Intensivmed Prax 5 : 1-8 9. Linshaw MA, Stapleton FB, Gruskin AB, Baluarte HJ, Harbin GL (1979) Traction-related hypertension in children. J Pediatrics 95 : 994-996 10. Little JA, Dean AE, Chapman M (1982) Immobilization Hypercakcemia. South Med J 75 : 502 11. Mardini MK, Mikati MA, Lifeso R (1981) Hypertensive encephalopathy: rare complication after orthopedic manipulation. Am J Dis Child 136 : 1092-1094 12. Miller A, Rosam MA (1983) Hypertensive encephalopathy as a complication of femoral lengthening. Can Med Assoc J 124 : 296-297 13. Milner LS, Thomson PD, Levin SE (1983) Traction-induced hypertension in a child. S Afr Med J 63 : 757 14. Streitz W, Brown JC, Bonnett C (1977) Anterior fibular strut grafting in the treatment of kyphosis. Clin Orthop 128 : 140148 15. Talab YA, Hamdan J, Ahmed M (1982) Orthopaedic Causes of Hypertension in Pediatric Patients. J Bone Joint Surg 64 [Am] : 291-292 16. Turner MC, Ruley EJ, Bnckley KM, Strife CF (1979) Blood pressure elevation in children with orthopedic immobilization. J Pediatrics 95 : 989-992 17. Whitehill R, Hakala W (1976) The hypertension of femoral lengthening: a canine experimental model. Surg Forum 26: 525-526 18. Whitehill R, Hakala MW (1978) Arterial hypertension induced by femoral lengthening, a canine model. J Bone Joint Surg 60 [Am] : 815-819 19. Wilk LH, Badgley CE (1963) Hypertension, another complication of the leg-lengthening procedure. J Bone Joint Surg 45 [Am] : 1263-1268 20. Yosipovitch ZH, Palti Y (1967) Alterations in blood pressure during leg-lengthening, a clinical and experimental investigation. J Bone Joint Surg 49 [Am] : 1352-1358
