Genu Valgum in Children: Diagnostic and Therapeutic Alternatives

Gregory R. White, MD, and Gregory A. Mencio, MD

Abstract

Genu valgum is a common orthopaedic problem in children. The vast majority femoral anteversion and compen- of cases are physiologic variants, which resolve normally. However, there are satory external tibial torsion may pathologic entities due to both focal and systemic processes in which the defor- have the appearance of valgus mity often progresses and usually requires treatment. Differentiating between malalignment of the knee when, in the two forms is facilitated by a thorough understanding of the natural history of fact, no frontal-plane deformity the development of the tibiofemoral angle in children. In this review, an approach exists. The appearance of genu val- to the evaluation and diagnosis of genu valgum is presented, and therapeutic gum in this situation is due to alternatives are discussed. malalignment in the transverse J Am Acad Orthop Surg 1995;3:275-283 (rotational) plane.

Pathologic Genu Valgum

Genu valgum, or knock-knee, is a and 22 months and progresses into Pathologic genu valgum is much common condition affecting the maximum valgus angulation (10 to less common than the physiologic lower limbs in children and adoles- 15 degrees) at around 3 years of age. type. However, numerous causes cents that the orthopaedist is often The normal child then has a gradual exist. Both focal and systemic called on to evaluate. As with genu resolution to physiologic knee val- processes may cause deformity that varum, physiologic forms are most gus (7 to 8 degrees) over the ensuing either is localized to a specific site common; however, pathologic years (Fig. 1). Using clinical tech- within the bone or is more general- causes, which have the propensity to niques of measurement, Staheli et ized, involving the whole bone. By progress and may require treatment, al2,3 have reported a similar pattern definition, children with pathologic do exist (Table 1). It is obviously of development. genu valgum have tibiofemoral important to distinguish between In the vast majority of children angles that are outside two standard these entities. In this review, we will with genu valgum, the tibiofemoral deviations of the mean.1-3 This mea- present an approach to the evalua- angle is within the physiologic surement varies as a function of age tion, diagnosis, and treatment of range of two standard deviations genu valgum in children. above or below the mean. They can be treated with observation and parental reassurance that the Dr. White is Chief Resident, Department of Orthopaedics and Rehabilitation, Vanderbilt Physiologic Genu Valgum “deformity” is a variant of normal University Medical Center, Nashville, Tenn. 1-3 and not a disease. Staheli has Dr. Mencio is Assistant Professor, Department Evaluating angular malalignment is suggested that such children are of Orthopaedics, Vanderbilt University School of simplified if one is familiar with the probably best described as having Medicine, Nashville. normal development of the tibio- knock-knees.2 Fat thighs, ligamen- femoral angle. Salenius and Vankka1 tous laxity, and flatfoot, which often Reprint requests: Dr. Mencio, Department of Orthopaedics and Rehabilitation, Vanderbilt have shown in a radiographic study results in toed-out habitus, can University Medical Center, Nashville, TN that the tibiofemoral angle in the accentuate the knock-kneed appear- 37232-2550. newborn is characterized by maxi- ance4 and cause physiologic genu mal lateral bowing (genu varum valgum to seem more severe. Tor- Copyright 1995 by the American Academy of angulation of 10 to 15 degrees). It sional malalignment can have a sim- Orthopaedic Surgeons. straightens between the ages of 20 ilar effect. Children with excessive

Vol 3, No 5, September/October 1995 275 Genu Valgum in Children

equate reduction or physeal injury gressive angular deformity.6 These Table 1 and subsequent growth arrest. In injuries should be looked for dili- Classification of Genu Valgum the proximal tibia, as in other parts gently, and families should be of the immature skeleton, Salter- informed of the potential conse- Physiologic Knock-knees Harris type III, IV, and V fractures quences to avoid subsequent Apparent genu valgum (fat pose the greatest risk of this occur- embarrassment, misunderstand- thighs, rotational deformity) rence. In contrast, several authors ing, and potential liability. Hresko Pathologic have shown that in the distal femur and Kasser6 recommend that all Idiopathic the fracture type is not predictive of patients with traumatic injury to Unresolved physiologic valgus future growth problems.5 Due to the lower extremity undergo radio- Lateral femoral hypoplasia the large cross-sectional area and graphic evaluation of the knee in Posttraumatic the convoluted anatomy of this addition to a thorough clinical eval- Malunion growth plate, damage to the physeal uation. Physeal arrest cartilage is probably extensive Another common cause of genu Metaphyseal tibial fracture despite the pattern of injury. Fur- valgum is tibia valga following Metabolic Rickets thermore, the geometry of this fracture of the proximal tibial me- Renal osteodystrophy physis may affect the ability to taphysis (Fig. 3). Since the first Neuromuscular achieve an adequate, anatomic description by Cozen7 in 1953, there Cerebral palsy reduction. have been many reports of this Paralytic conditions (e.g., It is worth mentioning that problem. Hosts of possible theories poliomyelitis) occult physeal injuries to the knee about etiology have been proposed, Infectious (e.g., osteomyelitis) may occur concomitantly with although the actual cause of the Generalized disorders more overt fractures of the metaph- abnormality remains unknown. Juvenile arthritis yseal and diaphyseal regions of the Cozen suggested that the problem Osteochondrodysplasia tibia and femur and can lead to pro- was due to asymmetric stimulation Osteogenesis imperfecta

(Fig. 1). Deformity is more apt to be +20° unilateral, and treatment is often necessary. +15°

Idiopathic Varus +10° Idiopathic genu valgum occurs when physiologic variants fail to +5° resolve, leading to persistent or progressive deformity. Children with 0° this diagnosis are often obese and flatfooted and characterized by liga- -5° mentous laxity.4 Hypoplasia of the lateral femoral condyle and stretch- Valgus -10° ing of the medial soft-tissue struc- tures of the knee may develop in response to prolonged, excessive -15° weight-bearing through the lateral half of the joint (Fig. 2). 1 2 345 6 7891011 12 13 Age, yr Posttraumatic Trauma is probably the most Fig. 1 Graph illustrating the development of the tibiofemoral angle in children during growth, based on measurements from 1,480 examinations of 979 children. Of the lighter common cause of pathologic genu lines, the middle one represents the mean value at a given point in time, and the other two valgum. Fractures of the distal represent the deviation from the mean. The darker line represents the general trend. femur or proximal tibia can lead to (Adapted with permission from Salenius P, Vankka E: The development of the tibiofemoral angle in children. J Bone Joint Surg Am 1975;57:259-261.) valgus deformity due to either inad-

276 Journal of the American Academy of Orthopaedic Surgeons Gregory R. White, MD, and Gregory A. Mencio, MD

and postulated that medial soft-tissue interposition was the cause of the deformity. More recently, Jordan et al13 reported on seven patients with this deformity, reviewed the major theories regarding the etiology of this problem, and concluded that the most likely primary mechanism is growth stimulation of the medial portion of the proximal tibia due to fracture hyperemia. This is cur- rently the prevailing theory and is strongly supported by the findings in two case reports. Green14 reported a case of posttraumatic tibia valga in which the mechanism of medial overgrowth of the proximal tibia was supported by the finding of asymmetric growth-arrest lines. Zionts et al15 reported a case of tibia A B valga that showed increased radionuclide activity in the medial half of the proximal tibial growth plate on a bone scan.

Metabolic Metabolic causes of pathologic Fig. 2 Idiopathic genu valgum in an obese genu valgum include the various teenager in whom physiologic valgus failed forms of rickets and renal osteodys- to resolve. Note the asymmetric involvement (greater on the left) and the hypoplasia trophy. Although the metabolic of the lateral femoral condyle, suggesting effects on the physis are similar in excessive lateral loading. these disorders, vitamin D–resistant and vitamin D–deficient rickets are more typically associated with varus deformity at the knee, and of the proximal tibial physis.8 Tay- renal osteodystrophy is typically lor9 attributed it to overgrowth of associated with valgus deformity.16 the tibia relative to the fibula. This difference is thought to be Salter and Best10 felt that mal- related to the pattern of mechanical union was the most important fac- loading of the physes as determined tor in the pathogenesis of the by the alignment of the knee at the valgus angulation. Houghton and time the metabolic process mani- Rooker11 experimentally produced fests itself.17 tibia valga in rabbits by sectioning Most of the disorders that are the pes anserinus and medial responsible for vitamin D–resistant C periosteum and postulated a teth- and vitamin D–deficient rickets are present from birth. Therefore, the ering effect of the intact lateral Fig. 3 Serial radiographs showing genu periosteum as the mechanism. metabolic abnormality is usually valgum due to inadequate initial reduction Weber12 surgically explored two established when the child begins to of a proximal metaphyseal tibial fracture in stand. The physiologic tibiofemoral a 7-year-old child. A, Inadequate reduction. cases of posttraumatic valgus, B, Malunion at the time of cast removal. C, found the pes anserinus trapped alignment at this age predisposes to Resultant valgus at 1-year follow-up. between the fracture fragments, progressive varus malalignment

Vol 3, No 5, September/October 1995 277 Genu Valgum in Children according to the Heuter-Volkman Neuromuscular principle, which states that epiphy- Genu valgum may be seen in chil- seal growth is inversely propor- dren with neuromuscular disorders. tional to the pressure applied to its Ambulatory children with cerebral longitudinal axis. palsy and other neuromuscular dis- For similar reasons, renal osteo- orders often have pes valgus and/or dystrophy causes genu valgum excessive external tibial torsion, because children are generally older which causes the foot to be rotated when the metabolic effects become externally relative to the knee (Fig. manifest. Valgus tibiofemoral align- 5). As a result of this malalignment, ment has usually developed, and valgus and external-rotation ground- subsequent mechanical forces acting reaction forces are generated against across the epiphyseal plate predis- the knee during stance. With growth pose to the development of progres- and continued weight-bearing, these sive valgus deformity (Fig. 4). abnormal forces can lead to progres- Oppenheim et al18 have described sive valgus deformity in the foot and changes in the lateral proximal tibia at the ankle and knee.19 In children in children with renal osteodystro- with spina bifida and other paralytic phy similar to those seen in the conditions, such as poliomyelitis, medial proximal tibia in Blount’s genu valgum is thought to be caused disease. by contracture of the iliotibial band20 Fig. 5 Ambulatory 11-year-old child with neuromuscular disorder. External rotation of the foot is due to pes valgus and external tibial torsion. As a consequence, the ground- reaction force passes lateral to the normal weight-bearing line, potentiating deformity in the foot and ankle and creating a valgus moment at the knee, which in time can lead to progressive deformity there as well.

and by the cumulative effects of abnormal dynamic forces (valgus thrust) produced by walking with a Trendelenburg or other compen- satory gait pattern.

Infectious Osteomyelitis can cause genu valgum directly, by disrupting the growth plate, or indirectly, by inducing reactive hyperemia and asymmetric growth stimulation. The latter are the mechanisms by which genu valgum is presumed to occur in children with juvenile arthritides, in whom hyperemia due to chronic synovitis may asymmetri- cally stimulate the physes around A B the knee.21

Fig. 4 Clinical appearance (A) and standing anteroposterior radiograph (B) of a 12-year- old child with chronic renal failure. Note the distal femoral physeal irregularities. Genu val- Generalized Disorders gum is the most common skeletal manifestation of renal osteodystrophy. Genu valgum also occurs in children with hereditary skeletal disor-

278 Journal of the American Academy of Orthopaedic Surgeons Gregory R. White, MD, and Gregory A. Mencio, MD ders, such as multiple epiphyseal way between the malleoli to define radiographs are helpful in assessing dysplasia and pseudoachondropla- two axes that closely approximate the sagittal plane if deformity is sus- sia, and in other generalized disor- the tibiofemoral angle. The tech- pected or surgery is being considered. ders characterized by severe nique is simple and reproducible, Tomograms are helpful in identifying osteopenia, such as osteogenesis and it provides an objective visual the presence of a physeal bar. imperfecta. record of the deformity that other Children with idiopathic genu val- clinical techniques do not. gum may have flattening of the lateral Rotational alignment (in particu- femoral condyle. Those with genu Evaluation lar, femoral anteversion and external valgum of posttraumatic origin will tibial torsion) and ligamentous laxity have evidence of a malunited fracture, The assessment of genu valgum should be assessed because of the a physeal bar, or asymmetric growth- should include a thorough history, potentially synergistic effect of these arrest lines. In children with rickets or including inquiries about the birth conditions on angular malalignment. renal osteodystrophy, widening and history, gross motor developmental Ligamentous laxity is defined clini- irregularity of the physes will be seen, sequence, family history, and cally on the basis of the presence of and there may be changes in the lateral dietary history. Parental concerns joint hyperextensibility. Examination proximal tibia. Children with genu are usually related to cosmesis, of rotational alignment is best done valgum due to chronic disease clumsiness, and future functional with the patient prone and the hips processes usually have generalized performance. Children with physio- extended and knees flexed. In this osteopenia. Those with osteochon- logic valgus usually have a normal position, hip rotation and the foot- drodystrophies will have changes of gestational and birth history and thigh angle can be easily measured as disordered growth and ossification in have reached developmental mile- estimates of femoral anteversion and the epiphyses or metaphyses at multi- stones at appropriate intervals. tibial torsion, respectively. ple sites. These findings will usually However, the family history may Children with physiologic genu be identified on the standing radio- reveal that there have been other sib- valgum are typically less than 7 graph and can be delineated further lings or family members for whom years old, have symmetric involve- by a more directed radiographic there were similar concerns and ment of the lower extremities, and investigation, if necessary. findings. The growth pattern and are of normal stature. The tibio- In most cases, measurement of dietary history are usually normal. femoral angle measures less than 15 the tibiofemoral angle (anatomic Children with pathologic genu val- degrees, and the intermalleolar dis- axis) will reasonably reflect the mag- gum typically have a history of pro- tance is less than 8 cm.3 Gait is nor- nitude of the valgus deformity and gressive deformity and, depending mal. Further diagnostic tests and can be used to track progression. on the underlying cause, a history of radiographs are usually not neces- However, as pointed out by Davids trauma, infection, dietary defi- sary in this situation. et al,17 this angle, which primarily ciency, or systemic illness. Radiographs are warranted, how- measures the relative diaphyseal Physical examination should ever, if pathologic genu valgum is alignment of the two bones, may not include an accurate assessment of suspected. Greene22 and Staheli23 accurately reflect the site or severity the patient’s stature to allow deter- recommend them if the deformity is of deformity, particularly when mination of the growth percentile. severe or asymmetric, if there are there is more generalized involve- The location of the deformity should other musculoskeletal abnormalities, ment of the long bones. For this rea- be noted, and the severity of the if the height is less than the 25th per- son, measurement of hip, knee, and angulation should be documented centile value, or if the family history ankle-joint orientation relative to the by either goniometric measurement is positive. In general, children with weight-bearing axis (mechanical- of the tibiofemoral angle or, more short stature, asymmetric involve- axis alignment) is considered a more simply, by linear measurement of ment, or a tibiofemoral angle greater accurate way to characterize the the distance between the medial than 15 to 20 degrees should be eval- deformity (Fig. 6).17,22-24 malleoli with the patient supine and uated radiographically. A single the knees together, as advocated by weight-bearing anteroposterior Howorth.4 Heath and Staheli3 have radiograph of the lower extremities Treatment described a photographic technique that includes the hips, knees, and of determining the knee angle, ankles allows measurement of align- Children with physiologic genu val- which uses the anterior superior iliac ment and assessment of any osseous gum, by definition, do not require spine, the patella, and a point mid- or physeal abnormality. Lateral treatment. Braces are impractical,

Vol 3, No 5, September/October 1995 279 Genu Valgum in Children poorly tolerated, and totally unneces- Children who are less than 10 The goal of operative treatment of sary for a condition with a benign nat- years old and have a tibiofemoral pathologic genu valgum is restoration ural history.22,23 Orthotics and shoe angle greater than 15 to 20 degrees of normal mechanical-axis alignment modifications do not affect the biome- and/or an intermalleolar distance of and joint orientation. Operative cor- chanics of growth and alignment at more than 8 cm,1-4,22,23 those of short rection of genu valgum can be accom- the knee.22 Moreover, these modali- stature or with asymmetric involve- plished by partial epiphysiodesis,25 ties are expensive and can be physi- ment, and those with progressive hemiepiphyseal stapling,4,21,26,27 or cally and psychologically stressful to deformity after age 4 years should be osteotomy.16,22,23 children and their parents. Instead, evaluated radiographically and fol- the child should be evaluated thor- lowed up clinically to rule out devel- Partial Epiphysiodesis oughly, and the parents should be opmental or metabolic causes. If a Partial epiphysiodesis, as advo- given a timely explanation of their tibiofemoral angle of more than 15 cated by Bowen et al,25 is the sim- child’s diagnosis, the expected resolu- degrees or an intramalleolar dis- plest procedure. It can be performed tion of the “problem,” and the impro- tance of 10 cm persists after age 10 through a standard incision that priety of nonoperative treatment. years, spontaneous correction is exposes the growth plate, or it can be Despite the generally favorable nat- unlikely to occur, and operative done percutaneously, with fluoro- ural history, some cases of knock- treatment is likely to be neces- scopic guidance. Either way, the knees will progress. sary.3,4,25 goal is to create a bridge crossing the

A B C D E

Fig. 6 A, Mechanical-axis and joint-orientation angles that define normal frontal plane alignment. A line drawn from the center of the femoral head to the center of the ankle defines the mechanical axis. The line normally passes 1 cm medial to the center of the knee. These relationships can be used to characterize the source and severity of valgus malalignment, as advocated by Paley et al.28 B, A mechanical- axis line passing through the lateral half of the knee joint defines valgus malalignment. C, Valgus deformity in the tibia is characterized by a medial proximal tibial angle (MPTA) greater than 90 degrees. D, Valgus deformity in the femur is characterized by a lateral distal femoral angle (LDFA) less than 85 degrees. E, Combined deformity. (Parts B-E adapted with permission from Paley D, Herzenberg JE, Tetsworth K, et al: Deformity planning for frontal and sagittal plane corrective osteotomies. Orthop Clin North Am 1994;25:428.)

280 Journal of the American Academy of Orthopaedic Surgeons Gregory R. White, MD, and Gregory A. Mencio, MD physis opposite the apex of the compensated for by premature clo- Typically, the apex of deformity in deformity, around which angulation sure of the physis on the same side, genu valgum is at the level of the can be corrected. overcorrection by approximately 5 physis or closer to the joint. Correction is predicated on contin- degrees is recommended to achieve Osteotomy at this level in either the ued growth in the contralateral half of the desired effect if staple removal is distal femur or the proximal tibia is the physis. Thus, the ability to predict necessary. Adolescent girls with a generally not feasible in skeletally remaining growth and its effect on skeletal age of 11 years and boys immature individuals. Thus, the angular deformity is crucial to achiev- with a skeletal age of 12 years are osteotomy must be performed at a ing a successful outcome. Bowen et generally the most suitable candi- level different from that of the defor- al25 developed a method that allows dates for this procedure. Epiphy- mity. Therefore, it must be designed correction of angular deformity to be seal stapling is not recommended not only to correct angulation but also correlated with linear growth with for children less than 10 years old to compensate for translation in order use of the Green-Anderson growth- because of the uncertainty of the to properly realign the extremity. remaining charts to help determine effects of rebound overgrowth and After osteotomy, stable internal the appropriate timing for surgery. concerns about premature physeal fixation augmented by a cast or Using this method of prediction, they closure.27 Since both epiphyseal sta- external fixation should be used to reported successful results in pling and hemiepiphysiodesis maintain correction until healing is 10 of 12 patients treated by partial result in some shortening of the complete. Alternatively, angular epiphysiodesis. limb, they are ideal surgical options deformity may be gradually cor- when the angular deformity is due rected with use of the principles of 23 Hemiepiphyseal Stapling to a process that causes chronic distraction osteogenesis. Using an When growth is predictable, par- hyperemia and overgrowth of the external fixator allows the osteot- tial epiphysiodesis is an excellent affected limb. omy to be adjusted postoperatively option. However, the procedure is to fine-tune alignment or to be repo- not reversible, and in conditions in Osteotomy sitioned in the event of neurovascu- which growth may be atypical, mis- Osteotomy is probably the most lar compromise. 29 timing surgery can lead to undercor- common method of correction of As pointed out by Steel et al, rection or overcorrection of the angular deformity. While osteotomy neurovascular complications after deformity. Therefore, when skeletal may be done at any age, it is usually osteotomy are probably more com- growth is not predictable, as in renal reserved until patients are near skele- mon than recognized. They include osteodystrophy, rickets, and other tal maturity. As with the other meth- compartment syndromes, ischemia metabolic conditions that cause gen- ods of correction of valgus deformity, due to stretch or compression of eralized bone involvement, epiphy- the goal of osteotomy is restoration of the anterior tibial artery, and neu- seal stapling may be a better option. physiologic mechanical-axis align- rapraxia due to traction on the per- First described by Blount and ment. If osseous deformity is gener- oneal nerve. The risks can be Clarke26 in 1949, this procedure is alized, correction at multiple sites reduced by avoiding acute valgus- intended to halt physeal growth by within the extremity and occasionally to-varus realignment when deformi- creating a peripheral bracket around even within a single bone may be nec- ty is particularly severe, routinely the physis that mechanically essary. Generally, correction can be performing prophylactic anterior- impedes longitudinal growth.27 achieved by dome, oblique-plane, compartment fasciotomy, draining Unlike epiphysiodesis, stapling does closing-wedge, or opening-wedge surgical wounds, and diligently not ablate the growth plate. If there osteotomies. Concomitant sagittal- monitoring neurovascular status is overcorrection, the effect is theo- and/or transverse-plane deformities postoperatively. retically reversible by removing the should be identified and corrected staples, if bar formation has not simultaneously. Relative Merits of Surgical occurred and if staple removal can The specifics of realignment Procedures be done without damaging the osteotomies are beyond the scope of Both epiphyseal stapling and par- growth plate in the process. this discussion. The important con- tial epiphysiodesis can be performed Restoration of growth is usually cept is that correction should be with less morbidity than is associ- attended by a rebound phenome- estab-lished as close to the center of ated with osteotomy.25-27,29 Correc- non caused by growth acceleration rotation of angulation of the deformi- tion is gradual, reducing the risk of on the previously stapled side of the ty as possible to avoid introducing a neurovascular complications. Fur- physis. Although this is partially translational deformity in the bone.28 thermore, because valgus deformity

Vol 3, No 5, September/October 1995 281 Genu Valgum in Children about the knee is typically in the jux- usually needs to be treated by pathologic genu valgum; it is taphyseal region of either the distal osteotomy. The patient’s metabolic unnecessary in the former and inef- femur or the proximal tibia, correc- profile must be stabilized as a pre- fective in the latter. Children more tion occurs at the appropriate level requisite to surgical treatment.16,17 than 10 years old with a tibio- opposite the center of rotation of the femoral angle greater than 15 deformity, resulting in restoration of degrees or an intermalleolar dis- mechanical-axis alignment. Summary tance of more than 10 cm are un- Posttraumatic genu valgum after likely to improve spontaneously a proximal tibial metaphyseal frac- Genu valgum is a common condi- and usually require operative treat- ture generally corrects sponta- tion in children. Physiologic vari- ment. The goal of treatment is neously over the course of 2 to 4 ants predominate and do not restoration of normal mechanical- years,29 and early osteotomy should require treatment. Pathologic genu axis alignment, which, depending be avoided.30 Residual deformity valgum is much less common, is on the underlying cause and the site can be effectively treated in adoles- more likely to progress, and usually and severity of the deformity, can cence by hemiepiphyseal stapling or requires treatment. Knowledge of be achieved by epiphyseal stapling, arthrodesis or by osteotomy, de- the natural history of the develop- partial epiphysiodesis, or oste- pending on the severity and the ment of the tibiofemoral angle is otomy. level of deformity. necessary to distinguish between Genu valgum associated with the two forms. Nonoperative treat- Acknowledgments: The authors are grate- ful to Dorothy Cochrane, Debbie Chessor, long-standing metabolic disorders is ment has no place in the manage- and Holly Quick for their assistance in the generally a complex deformity and ment of either physiologic or preparation of the manuscript.

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282 Journal of the American Academy of Orthopaedic Surgeons Gregory R. White, MD, and Gregory A. Mencio, MD

Chapman MW, Madison M (eds): Oper- liminary report. J Bone Joint Surg Am 29. Steel HH, Sandrow RE, Sullivan PD: ative Orthopaedics, 2nd ed. Philadel- 1949;31:464-478. Complications of tibial osteotomy in phia: JB Lippincott, 1993, vol 1, pp 27. Zuege RC, Kempken TG, Blount WP: children for genu varum or valgum: 883-948. Epiphyseal stapling for angular defor- Evidence that neurological changes are 25. Bowen JR, Torres RR, Forlin E: Partial mity at the knee. J Bone Joint Surg Am due to ischemia. J Bone Joint Surg Am epiphysiodesis to address genu varum 1979;61:320-329. 1971;53:1629-1635. or genu valgum. J Pediatr Orthop 1992; 28. Paley D, Herzenberg JE, Tetsworth K, et 30. Zionts LE, MacEwen GD: Spontaneous 12:359-364. al: Deformity planning for frontal and improvement of post-traumatic tibia 26. Blount WP, Clarke GR: Control of bone sagittal plane corrective osteotomies. valga. J Bone Joint Surg Am 1986; 68:680- growth by epiphyseal stapling: A pre- Orthop Clin North Am 1994;25:425-465. 687.

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