ANGULAR DEFORMITIES OF THE LOWER LIMBS IN CHILDREN

Robert N. Hensinger, M.D. Section of Orthopaedic Surgery University of Michigan Hospital TC 2914/0328 Ann Arbor, MI 48109 INTRODUCTION thrust () or medial thrust (genu valgum) occurs Angular malalignments, bow legs and knock , are (Fig. 1). Children with physiologic varus or valgus angu- a common concern in the early years of life. For the lation at the knees typically do not exhibit a thrust. How- majority of children, the problem represents a normal ever, in pathologic conditions a thrust is often present physiologic variation, and spontaneously corrects12'27'32. suggesting incompetence of the ligaments. Ligament A few will have pathologic malalignment leading to cos- incompetence increases the potential for continued pro- metic or functional problems requiring bracing or surgery. gression of the deformity37. Familiarity with the natural history of angular deformities The natural history of physiologic genu varum and genu and familiarity with normal growth patterns are necessary valgum has been defined by Salenius and Vankka32. They to evaluate malalignment. studied the development of the tibiofemoral angle in 1480 normal children (Fig. 2). The tibiofemoral angle within the PHYSIOLOGIC BOW LEGS AND KNOCK KNEES first year is 150 of varus. As the child approaches 18 months, the angle gradually increases to neutral, and the Clinical evaluation of angular deformities should include lower extremities appear straight. During the second and family history, any description of onset and information third years, the tibiofemoral angle increases to an average about progression of the deformity. A child who has of 12° of valgus. During the following years, the valgus assymptomatic findings or a brief history of rapid progres- alignment slowly decreases to that of the adult, 70 in male sion is particularly suspect because these suggest a seri- and 80 in females. When obtaining an AP roentgenogram ous condition such as a neurologic disorder, congenital of the knees to measure the tibiofemoral angle, the legs anomaly, tumor or infection. must be positioned in neutral rotation; external rotation The normal infant usually stands with the legs apart, will decrease and internal rotation will and the subcutaneous fat may mask early physiologic varus increase valgus angulation18. angulation. Internal tibial torsion often accompanies phys- iologic genu varum, and accentuates the bow-leg appear- +.15 ance while standing or walking. Pes planus and external tibial torsion may accompany genu valgum and similarly VARUS +10°F accentuate the appearance of knock knees. The child should be observed walking, with attention to + 5o the knees the stance phase to determine if lateral during 2 3 4 6 7-13 AA (YFRq-- L I * MM t T LSU% )r I1

- 50

VALGUS -101- Figure 1 Child with unilateral bow leg, dem- - 151_ onstrates the lateral thrust at stance phase. The weightbearing Figure 2 force is transmitted through the Development of the tibiofemoral angle during growth. Repro- medial tibiofemoral compartment, duced with permission from J. Bone and Joint Surg., 75A:259- slowing the growth of the medial 261, 1975. tibial physis. In the past, authors have recommended using the dis- tance between the femoral condyles to measure genu varum and the distance between the malleoli of the to measure genu valgum27,30. These measurements have never been shown as accurate or reproducible and do not allow for the normal variation in leg length.

16 The Iowa Orthopaedic Journal Angular Deformities of the Lower Limbs in Children

DIFFERENTIAL DIAGNOSIS OF GENU VARUM BLOUNT'S DISEASE In the young child, Blount's disease is the most common Blount's disease, osteochondrosis deformans , was cause of pathologic genu varum. However, the child should initially described by Erlacher in 1922 and the first large be evaluated to exclude other causes such as metaphyseal series was reported by Blount in 19375,13. Blount described dysplasia (Fig. 3), osteochondromatosis, hemihypertro- both an infantile and an adolescent form. The infantile form phy, fibular or tibial , multiple epiphyseal dyspla- is usually bilateral, progressive, associated with internal sia, osteochondrodystrophy, achondroplasia and fibrous tibial torsion, and appears as a pathologic continuation of dysplasia16. Trauma or infection involving the physis or physiologic genu varum. The adolescent form is less com- and fracture of the adjacent metaphysis can also mon, occurring in older children (9-14 years of age), typ- result in . Bone softening conditions such ically unilateral and less often associated with internal tibial as can cause varus or valgus knee deformities. torsion. Both forms are more common in blacks2'3"10'15. Usually the direction of the deformity is dependent on the Infantile tibia vara is a developmental problem charac- child's alignment at the onset of the condition. Thus, the terized as an abrupt angulation of the medial tibia, due to various forms of rickets can be associated with either genu a disturbance in growth of the posterior medial portion of varum or genu valgum. Onset of vitamin D deficiency or the proximal tibial epiphysis. In the advanced stages of vitamin D resistant rickets during the "bow-leg phase" will this condition there is an associated depression in the lead to more pathologic bowing. Genu valgum is typically posterior medial portion of the proximal tibia36. Pathologic associated with because the onset reports are sparse but demonstrate irregular cartilage of chronic renal disease generally occurs while children are columns, scattered areas of hypertrophic chondrocytes, in the valgus phase. Metabolic conditions such as rickets hypocellular fibrocartilage and delayed irregular ossification. affect the entire , while Blount's disease There is disagreement as to the etiology of the condi- involves only the medial aspect of the proximal tibia. tion. Langenskiold and Riska, and Blount all believed that it is caused by disturbance in growth and ossification of the medial part of the proximal tibial epiphysis and metaphysis5'6'24. However, it is not due to avascular necro- sis, infection or nutritional factors6"14'21'24. There are only scattered reports of familial bowing33'34'41. Others suggest that the problem develops as a result of early walking Three year old with meta- when physiologic genu varum is maximal. The weight physeal dysplasia. Findings bearing force is then transmitted across the medial tibiofe- inthe proximal tibia are sim- ilar to Blount's disease, moral compartment slowing the growth of the medial tibial however, similar changes are physis1 2'3'4'9"6' 19 If a lateral thrust has developed with found in the other meta- weight bearing (Fig. 1) in a child with genu varum, the physes of the lower extrem- ity, suggesting a generalized prognosis for improvement is poor37. Burke developed a condition. biomechanical model that demonstrates that in the 2 year old, 20 degrees of varus results in sufficient force to retard epiphyseal growth. In the 5 year old, only 10 degrees is needed to retard epiphyseal growth7. Langenskiold and Riska described six stages of roent- genographically visible progression based on epiphyseal is an inborn error of metabolism depression and metaphyseal fragmentation of the proximal characterized by low alkaline phosphatase activity. There medial tibia24. The children were grouped by radiographic are many forms of this condition, and the severely involved appearance (stage I through VI), depending on the degree child is not likely to survive infancy. Less severely involved of epiphyseal depression and metaphyseal fragmentation chdren have radiographic findings siinlar to vitamin D (Fig. 4). Medial fragmentation of the proximal tibial meta- resistant rickets. Children with hypophosphatasia, renal physis is the minimal finding for stage I (Fig. 5A). Isolated rickets and nutritional rickets have osteopenic bone while tibial bowing or beaking of the metaphysis is not consid- patients with vitamin D resistant rickets are likely to have ered diagnostic3 9. As the condition progresses, an increased normal . varus angulation is noted just distal to the proximal tibial The radiographic appearance of the epiphyseal plate in epiphyseal plate (Fig. 5B). The epiphyseal line medially is similar to rickets (Fig. 3). These becomes irregular and the epiphysis slopes medially (Figs. children have varying degrees of involvement from mark- 6A-B, 7A-B). As tensile forces increase laterally, there is edly disturbed metaphyses, to mild involvement of the often an accompanying widening of the epiphyseal plate distal or proximal tibia. and tilting of the epiphysis7.

Volume 9 17 R. N. Hensinger

IV

Ii III I v v Figure 4 Schematic drawing of the Langenskiold classification, depicting the six stages of progressive radiologic change of tibia vara from mild to severe. The higher stages have more medial deformity and fragmentation.

age II

Figure 6A-B (A) Langenskiold stage III. Note the sloping of the medial epi- physis. The metaphysis demonstrates further dissolution, frag- mentation and collapse. (B) Langenskiold stage IV. Sloping and further fragmentation of the proximal tibial metaphysis. Note the disappearance of the medial portion of the tibial epiphysis.

Figure 5A-B (A) Radiograph of Langenskiold stage I demonstrating mild blunting of the medial tibial epiphysis and beaking of the prox- imal medial tibial metaphysis. (B) Stage II demonstrates continuation of the process with radi- ographic fragmentation and radiolucencies in the medial prox- imal tibial metaphysis.

It is difficult to distinguish between the initial stage of infantile Blount's disease and the extreme physiologic genu varum9. Drenan suggested the use of the metaphyseal- diaphyseal angle to predict which children will progress from severe physiologic bow legs to Blount's disease25. On an anterior-posterior roentgenogram, a line is drawn perpendicular to the longitudinal axis of the tibia and another is drawn through the two beaks of the metaphysis to determine the transverse axis of the tibial metaphysis. The metaphyseal-diaphyseal angle is the angle bisected by these two lines. Angles less than 110 tend to resolve, while those greater than 110 progress to Blount's disease (Fig. Figure 7A-B 8A-B). (A) Langenskiold stage V. Complete absence of the medial tibial If Blount's disease progresses to stage VI, the medial epiphysis. It is difficult to tell without laminagraphic view if epiphyseal plate will fuse (Fig. 7 B). It is extremely the epiphyseal plate is open. (B) Langenskiold stage VI. Closure of the medial part of the important to recognize this radiographic transition from proximal tibial epiphyseal plate with a bone bridge evident radi- stage V to stage VI. Once the patient progresses to stage ographically between the two structures.

18 The Iowa Orthopaedic Journal Angular Deformities of the Lower Limbs in Children

Figure 8A-B The metaphyseal-diaphyseal angle. (A) A 2 year 1 month old demonstrating a 13 degrees metaphy- seal-diaphyseal angle suggestive of early Blount's disease. (B) Same patient at 2 years 5 months, demonstrating continued progression to 15 degrees. Figure 9A VI, surgical realignment will fail and recurrence of deform- The Denis-Blount brace utilizes a Denis-Browne bar to correct ity is inevitable. As the disease advances through stages initial tibial torsion and knee straps to correct bowing. II-V, the normal epiphyseal enchondral ossification is inhibited936. TREATMENT OF BLOUNT'S DISEASE Treatment of Blount's disease depends on the degree of deformity and the age of the patient. Infantile Blount's disease usually progresses rapidly during the first four Figure 9B years and then slowly during the remainder of growth24. A-frame design. A-frame Treatment is seldom required in patients younger than 18 is of rigid construction and maintains external months. If the varus deformity is not improving by 18-24 rotation and valgus align- months of age it should be treated with a nighttime orthosis ment with knee straps. which is effective up to the age of three years5'6'9'15. These younger children are generally treated with a Blount's brace or A-frame (Fig. 9A-B). The Blount brace utilizes a Denis-Browne bar to correct internal tibial torsion and the knee straps to correct the bowing. The A-frame is similar but of more rigid construction. In the older children, a double upright brace may be worn throughout the day. With brace treatment, most children with stage I or II of the growth plate (stage VI) are definite surgical indica- involvement can be expected to have satisfactory clinical tions that occur in the later stages of the disease (stage alignment and radiographic resolution of their disease28. Children with advanced stage II disease and all children A valgns external rotation performed at an with stage III disease or greater should be considered for early age will usually obtain complete and permanent cor- surgery. Once the deformity has progressed to stage III rection of the deformity. There is greater chance for or the tibiofemoral angle is more than 15 degrees, further recurrence if the osteotomy is done in later yearS24,27. attempts at bracing are unwarranted, and surgery should The surgical technique includes a tibial osteotomy cor- be recommended15 (Fig. 10). Similarly, operative correc- recting the internal tibial torsion, over-correcting the varus tion is indicated in stage II if the deformity is persistent deformity, and a fibular osteotomy through a separate despite adequate brace treatment. The development of incision. If the epiphyseal plate is open, the osteotomy is ligament laxity, depression of the tibial plateau, or the performed below the insertion of the patellar tendon to roentgenographic appearance of impending medial closure avoid damage to the anterior apophyseal extension. The

Volume 9 19 R. N. Hensinger

avoid this problem. Intraoperative roentgenograms or arthrograms are helpful in assuring satisfactory correction iX } 1 X 6+ 3 | of the angular deformity"1. The internal tibial torsion must also be corrected with the osteotomy. In Langenskiold's series, the osteotomy prevented further progression if done before eight years of age. In our series, we have had several cldren younger than eight years who required a second procedure and a few who presented with stage VI disease. However, we would agree that younger children with earlier stages of disease are more likely to have a satisfactory result22'23'28 We were uniformly unable to prevent stage IV from becoming stage VI with osteotomy alone. Previously, if medial fusion of the epiphyseal plate occurred a final realignment and was recommended. How- ever, more recent attempts at epiphyseal bridge resection and interposition of material have met with encouraging results28. In children in whom early closure cannot be prevented, closure of the lateral epiphyseal plate and prox- imal fibula should be accomplished promptly to prevent further angular deformity. A timely epiphyseodesis of the opposite tibia should be considered to minimize leg length Figure 10 discrepancy,2'40'42 A child aged 6 years 3 months, with bilateral infantile Blount's A proximal tibial osteotomy in a child presents a poten- disease. The involvement is asymmetric with a stage IV on the D right and a stage II on the left. Both require surgical correction C D by osteotomy. osteotomy may be performed at the level of the epiphyseal plate if the growth is complete or if an epiphysiodesis is necessary. To achieve normal development of the medial epiphysis, the valgus osteotomy must shift the weight bearing forces to the lateral plateau37 (Fig. 11A-D). Liga- ment laxity and posterior medial depression of the plateau are frequent causes of inadequate correction and recur- rence of deformity36. Over-correction is reconmnended to A R

Figure 11A-D (A)(C) Five year old with advanced Blount's disease (stage III- (B)(D) Satisfactory radiographic and clinical appearance two IV). years following bilateral tibial .

20 The Iowa Orthopaedic Journal Angular Deformities of the Lower Limbs in Children tial hazard and all should be observed carefully for com- promise of the neurovascular status of the extremity in the postoperative period38'42. Steel and coworkers docu- mented significant compromise of the neurovascular struc- tures of the lower extremities in 20 percent of children undergoing proximal tibial osteotomy and suggested that the problem is due to entrapment of the anterior tibial 14+9 )ost- artery following correction, not to injury of the peroneal or nerve38. They recommended that if neurovascular com- promise occurs following proximal tibial osteotomy, the limb should be immediately returned to the uncorrected position. ADOLESCENT BLOUNT'S DISEASE Adolescent tibial Blount's disease is a separate disease from the infantile form5 6'23. It is usually unilateral, occur- ring in an older age group averaging 12.5 years (range 10- 14 yrs.), and typically occurs without previous history of bowing. Radiographically, the epiphyseal height is normal and the physis is widened medially and not depressed2l 24'43 (Fig. 12). There is a strong relationship with obesity40'43. Also, there is an association of adolescent Blount's disease Figure 13*A-B with slipped capital femoral epiphysis and tarsal coalition (A) This 14 years 9 month old has achieved skeletal maturation suggesting mechanical factors as an etiology26. From review and no further growth of the proximal tibial epiphysis is anticipated. of the literature and our own experience, bracing is inef- (B) The osteotomy was performed at the epiphyseal plate. fective in controlling the progression of adolescent Blount's disease40'43. Once initiated, the deformity progresses until apophysis. An epiphyseodesis of the contralateral tibia growth is complete40'41'43 may be required to prevent leg length discrepancy. Occa- sionally, as in the infantile form, medial fusion of the epi- physeal plate occurs prior to lateral fusion leading to

:114+8 . recurrence of the deformity20'23. Neurovascular compro- mise or fracture of the osteotomy into the joint are pos- sible complications of any proximal tibial osteotomy. Figure 12 Adolescent Blount's disease in a 14 years 8 months old with typical unilateral evolvement. DIFFERENTIAL DIAGNOSIS OF GENU VALGUM In addition to bowing other Renal osteodystrophy secondary to chronic renal insuf- radiographic features include widening of the epiphyseal line ficiency (renal rickets) is now the most frequent cause of medially and the absence of a pathologic genu valgum (Fig. 14). Improved medical depressed tibial epiphysis. management, general availability of renal dialysis, and kid- ney transplantation have significantly increased longevity in these children. Thus, correction of these deformities by osteotomy is reasonable and should be performed if severe. Less commonly, obese children can develop idi- opathic genu valgum. Additionally, osteochondroma about Complete resolution of the condition can be expected if the distal femur or proximal tibia may cause differential the deformity is sufficiently corrected at the first growth leading to a valgus deformity or, less often, varus surgery2l"24'40'43 (Fig. 13A-B). If the epiphyseal plate is (Fig. 15). closed, a proximal tibial osteotomy similar to that described Direct injury to the epiphyseal plate of the proximal tibia by Coventry can be done through the old epiphyseal scar. or distal femur (such as a Salter IV or V injury) may result If the epiphyseal plate is open, osteotomy below the inser- in a late angular deformity. In the younger child, injury to tion of the patellar tendon is indicated. This preserves the tibial metaphysis can also cause progressive valgus or further epiphyseal growth and avoids disturbing the tibial late angulation. The unilateral valgus deformity following

Volume 9 21 R. N. Hensinger

Figure 14 Four year old with genu val- gum secondary to renal osteodystrophy.

Figure 16 Metaphyseal dysplasia causing genu valgum. These changes are similar to those seen in rickets and renal osteodystrophy.

age may be safely ignored unless the tibiofemoral angle is Figure 15 greater than 150, the valgus is symptomatic or the condi- Multiple osteochondromato- stature42. Another sis causing bilateral genu tion is accompanied by shortened valgum. exception is the young child with unilateral valgus following proximal tibial fracture. In this case, treatment using a genu valgum brace worn for about one year is usually successful18. Howorth believed that by the age of ten a genu valgum deformity greater than three inches (meas- ured between the medial malleoli with the knees together) was not likely to correct with time'7. Although little sup- port exists in the literature, Howorth believed that exces- an undisplaced or miinimnally displaced fracture of the medial sive genu valgum contributed to awkwardness of gait, side of the proximal tibial metaphysis desires special subluxing patellae, easy fatigability and joint pains. emphasis. Jackson and Cozen reported that genu valgum is a potential sequelae of this fracture when sustained in Corrective surgery may be necessary if the remaining chidren three to nine years of age18. The resultant valgus growth potential is limited or the genu valgum is severe. may be over 15' and is usually recognized after the fracture Howorth and others recommended surgical stapling of the heals. The development of genu valgum has been attrib- medial tibial and femoral epiphysis for correction of exces- uted to a discrepancy in growth between the tibia and sive genu valgum17'44. The amount of correction from fibula with the fibula exerting a tethering effect39. The stapling is unpredictable since a rebound increase in medial parents of these children must be informed of this potential growth occurs when the staples are removed. Zuege et complication. al. suggested allowing for 5 degrees of rebound'. Cur- As with genu varum, infections, tumors, congenital rently, stapling is not recommended prior to a skeletal age anomalies and hereditary conditions such as metaphyseal of 11 in girls and 12 in boys. The stapling should be timed dysplasia can cause angular deformity. These can generally to coincide with closure of the growth plate. Bowen has be identified on initial radiographs (Fig. 16). Paralytic dis- devised a simple chart for timing of the stapling procedure orders such as cerebral palsy and polio can cause both to achieve satisfactory alignment at completion of growth8. rotational and valgus deformity due to a tight iliotibial band. These children should be followed closely because over- This leads to valgus at the knees and external rotation of correction may develop. Correction of the valgus deform- the tibia. ity that occurs with osteochondromatosis is an ideal use of staples to avoid osteotomy. In these children, the enlarged TREATMENT OF GENU VALGUM irregular tibia and femur increase the potential for neuro- Genu valgum in chidren younger than seven years of vascular compromise following osteotomy.

22 The Iowa Orthopaedic Journal Angular Deformities of the Lower Limbs in Children

SUMMARY 14- Evensen, A., and Steffensen, J.: Tibia Vara (Osteo- During the early years of childhood, genu valgum and chondrosis Deformans Tibiae). Acta. Orthop. Scand., genu varum are common concerns for parents. These 26:200-210, 1957. problems represent normal physiologic variations in most 15- Golding, J.S. R., and MacNeil-Smith, J.D. G.: Obser- children. However, a few children will experience patho- vations on the Etiology of Tibia Vara. J. Bone and Joint logic lower extremity malalignment leading to cosmetic and Surg., 45B:320-325, 1963. functional deficits. Although several exist, the most fre- 16- Hanson, L.I., and Zayer, M.: Physiological Genu Varum. quent causes of pathologic genu varum and genu valgum Acta. Orthop. Scand., 46:221-229, 1975. are Blount's Disease and renal rickets respectively. Treat- 17- Howorth, B.: Knock Knees. Clin. Orthop., 77:233, ment of genu valgum and genu varum includes observation 1971. for the lesser deformities, bracing for moderate deformi- 18. Jackson, D.W., and Cozen, L.: Genu Valgum as a Com- ties and surgical correction for the excessive deformities. plication of Proximal Tibial Metaphyseal Fractures in Chil- dren. J. Bone and Joint Surg., 53A: 1571, 1971. BIBLIOGRAPHY 19. Kessel, L.: Annotations on the Etiology and Treatment ' Arkin, A.M., and Katz, J. F.: The effects of pressure of Tibia Vara. J. Bone and Joint Surg., 52B:93-99, 1970. on epiphyseal growth. The mechanism of plasticity of 20- Kling, T.F., Jr.: Tibia Vara: A Mechnaical Problem. growing bone. J. Bone and Joint Surg., 38A: 1056-1076, Orthop. Trans., 5:138, 1981. 1956. 21- Langenskiold, A.: Tibia Vara (Osteochondrosis Defor- 2- Bateson, E.M.: Non-rachitic Bow Leg and Knock-Knee mans Tibiae). A Survey of 23 cases. Acta. Chir. Scand., Deformities in Young Jamaican Children. Brit. J. Radiol., 103:1-22, 1952. 39:92-101, 1966. 22- Langenskiold, A.: An Operation for Partial Closure of 3 Bateson, E.M.: The Relationship Between Blount's an Epiphyseal Plate in Children, and its Experimental Disease and Bow Legs. Brit. J. Radiol., 41:107-114, 1968. Basis. J. Bone and Joint Surg., 57B:325-330, 1975. 4- Bathfield, C.A., and Beighton, RH.: Blount Disease. 23- Langenskiold, A.: Tibia Vara: Osteochondrosis Defor- A Review of Etiological Factors in 110 Patients. Clin. mans Tibiae. Blount's Disease. Clin. Orthop., 158:77-82, Orthop., 135:29-33, 1978. 1981. 5- Blount, W R: Tibia Vara. J. Bone and Joint Surg., 19:1- 24- Langenskiold, A., and Riska, E.B.: Tibia Vara (Osteo- 29, 1937. chondrosis Deformans Tibiae): A Survey of 71 Cases. J. 6- Blount, W.R: Tibia Vara, Osteochondrosis Deformans Bone and Joint Surg., 46A1405-1420, 1964. Tibiae. Curr. Pract. Orthop. Surg., 3:141-156, 1966. 25- Levine, A. M., and Drennan, J. C.: Physiological Bow- 7- Burke, S.W.; Cook, S.D.; Lavernia, C.J.; Skinner, ing and Tibia Vara. The Metaphyseal-Diaphyseal Angle in H. B.; and Haddad, R.J., Jr.: A Biomechanical Analysis of Measurement of Bow Leg Deformities. J. Bone and Joint the Etiology of Tibia Vara. Orthop. Trans., 7:442, 1983. Surg., 64A:1158-1163, 1982. 8- Bown, J.R.; Leahey, J.L.; Zhang, A.; and MacEwen, 26- Lovejoy, J.F., Jr., and Lovell, WW.: Adolescent Tibia G.D.: Partial Epiphysiodesis at the Knee to Correct Angular Vara Associated with Slipped Capital Femoral Epiphysis. Deformity. Clin. Orthop., 198:184-190, 1985. Report of Two Cases. J. Bone and Joint Surg., 52A:361- 9 Bradway, J. K.; Klassen, R.A.; and Peterson, H.A.: 364, 1970. Blount's Disease: A Review of the English Literature. J. 27. McDade, W: Bow Legs and Knock Knees. Pediat. of Pediatric Orthopedics, 7:472-480, 1987. Chin. North Am., 24:825, 1977. 10. Currarino, G., and Kirks, D. R.: Lateral Widening of 28. Meade, W.C.; Schoenecker, P.L.; Pierron, R.L.; and Epiphyseal Plates in Children with Bowed Legs. Am. J. Capelli, R.N.: Blount's Disease-a Retrospective Review Roentgenol., 129:309-312, 1977. and Recommendations for Treatment. Orthop. Trans., 1'- Dalinka, M. K.; Coren, G.; Hensinger, R.N.; and Irani, 7:441, 1983. R. N.: Arthrography in Blount's Disease. Radiology, 29- Medbo, I.: Tibia Vara (Osteochondrosis Deformans 113:161-164, 1974. Tibiae or Blount's Disease). Treatment and Follow-up 12- Engle, G.M., and Staheli, L.T.: The Natural History Examination. Acta. Orthop. Scand., 34:323-336, 1964. of Torsion and other Factors Influencing Gait in Child- 30. Pitkow, R.B.: External Rotation Contracture of the hood. Chin. Orthop., 99:12,1974. Extended . Clin. Orthop., 110:139, 1975. 13- Erlacher, R: Deformierende Prozesse der Epiphysen- 31- Rechnagel, K.: Associated with gegend bei Kindern. Arth. Orthop. Unfall-Chir, 20:81-96, Slipped Capital Femoral Epiphysis. Acta. Orthop. Scand., 1922. 44:505-508, 1973.

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32. Salenius, P., and Vankka, E.: The Development of the 39 Taylor, S. L.: Tibial Overgrowth: A Cause of Genu Tibiofemoral Angle in Children. J. Bone and Joint Surg., Valgum. J. Bone and Joint Surg., 45A:659, 1963. 57A:259-261, 1975. 40. Thompson, G.H.; Carter, J.R.; and Smith, C.W.: Late 33- Sevastikoglou, J.A., and Eriksson, I.: Familial Infantile- Onset Tibia Vara: A Comparative Analysis. Orthop. Trans., Osteochondrosis Deformans Tibiae. Idiopathic Tibia Vara. 7:441-442, 1983. Acta. Orthop. Scand., 38:81-87, 1967. 41- Tobin, WJ.: Familial Dissecans with 34- Sibert, J.R., and Bray, PT.: Probable Dominant Inher- Associated Tibia Vara. J. Bone and Joint Surg., 39A: 1091- itance in Blount's Disease. Clin. Genetics, 11:394-396, 1105, 1957. 1977. 42. Van Oln, J.M.J., and Gillespie, R.: Proximal Tibial 35 Siegling, J.A., and Gillespie, J.B.: Adolescent Tibia Osteotomy for Angular Knee Deformities in Children. Vara. Radiology, 32:483-485, 1939. Orthop. Trans., 7:443, 1983. 36. Siffert, R.S., and Katz, J.F.: The Intra-articular 43 Wenger, D.; Mickelson, M.; and Maynard, J.: The Deformity in Osteochondrosis Deformans Tibiae. J. Bone Evolution and Histopathology of Adolescent Tibia Vara. and Joint Surg., 52A:800-804, 1970. Orthop. Trans., 7:477, 1983. 37- Smith, C.F.: Current Concepts Review. Tibia Vara 44 Zuege, R. C.; Kempken, T. G.; and Blount, W.P.: Epi- (Blount's Disease). J. Bone and Joint Surg., 64A:630-632, physeal Stapling for Angular Deformities of the Knee. J. 1982. Bone and Joint Surg., 61A:320, 1979. 38- Steel, H.H.; Sandrow, R.E.; and Sullivan, P.D.: Com- plications of Tibial Osteotomy in Children for Genu Varum or Valgum. Evidence that Neurologic Changes are Due to Ischemia. J. Bone and Joint Surg., 53A: 1629, 1971.

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24 The Iowa Orthopaedic Journal