Blount’s Disease. Madelung’s Deformity.

Introduction

This chapter addresses two distinct but classically grouped focal developmental disorders of growth: Blount’s disease (tibia vara), a disorder of the medial portion of the proximal tibial physis producing progressive varus deformity of the proximal tibia; and Madelung’s deformity, a disorder of the ulnar-volar portion of the distal radial physis producing characteristic deformity of the wrist with palmar and ulnar tilt of the distal radius. Both conditions share the underlying pathological theme of asymmetric or partial physeal arrest producing progressive angular deformity, and both demand recognition by the orthopedic surgeon for the planning of conservative or surgical management. Content is synthesized from Tachdjian’s Pediatric Orthopaedics, Apley & Solomon’s, Miller’s Review, and Netter’s Concise Orthopaedic Anatomy.

Blount’s Disease (Tibia Vara)

Definition and Epidemiology Blount’s disease — proximal tibia vara — is a developmental disorder of the medial portion of the proximal tibial physis producing progressive varus deformity, internal tibial torsion, and procurvatum of the proximal tibia. The condition was first described by Walter Putnam Blount in 1937, who recognized that the disorder, although superficially resembling physiological bowing, had a distinct natural history of progression rather than spontaneous resolution. Two forms are recognized: infantile Blount’s disease (onset before age 4), which is the most common form; and adolescent Blount’s disease (onset between age 10 and skeletal maturity), which is less common but has distinct features. The infantile form has a strong association with early walking (the typical patient is a heavyset toddler who began walking before age 1), obesity, African descent (substantially higher prevalence than in European-descended children), and family history. The adolescent form is strongly associated with obesity and is more common in African American adolescents. The condition is bilateral in approximately 60-80% of infantile cases and 50% of adolescent cases. Other reported associations include vitamin D deficiency, hypocalcemia, and certain dietary factors. Pathophysiology The fundamental pathological process is a focal growth retardation of the medial portion of the proximal tibial physis (with the medial side of the metaphysis and epiphysis also affected), while the lateral side continues to grow normally. Multiple theories have been proposed for this asymmetric growth retardation, with the principal candidates being mechanical (the Hueter-Volkmann principle, that increased compression on the medial proximal tibial physis from varus alignment and excess body weight inhibits growth) and biological (intrinsic developmental defects of the medial physis in susceptible individuals). The interaction of early walking (which produces a large axial load before the medial

physis has matured), obesity (which increases this load), and genetic susceptibility (which determines the threshold for response) explains the typical clinical presentation. The progressive nature of the condition reflects a positive feedback loop: the varus alignment increases medial compression, which further inhibits medial growth, which worsens the varus. Without intervention, severe deformity with associated growth-plate disturbance and ultimately bony bar formation can develop. Classification The Langenskiöld classification (1952), based on radiographic appearance of the medial proximal tibial epiphysis and metaphysis, recognizes six stages of increasing severity: Stage I: Medial metaphyseal beaking with no involvement of the epiphysis. Stage II: Wedging of the medial epiphysis with sharp metaphyseal beak. Stage III: Step-off at the medial epiphyseal margin with fragmentation. Stage IV: Occupation of the medial epiphyseal step by the metaphyseal beak. Stage V: Cleft of the medial epiphysis with separated medial fragment. Stage VI: Bony bridging across the medial physis with established bony bar. The classification has prognostic value (Stages V and VI rarely improve without surgical intervention; Stages I and II can resolve with conservative management) but inter-observer reliability is only moderate. The Drennan metaphyseal-diaphyseal angle is a quantitative measurement used to distinguish infantile Blount’s disease from physiological bowing. The angle is measured between (1) a line through the most prominent points of the proximal tibial metaphysis and (2) a line perpendicular to the long axis of the tibial diaphysis. Angles less than 11° suggest physiological bowing; angles greater than 16° suggest Blount’s disease; intermediate angles (11-16°) are equivocal and require further evaluation and follow-up. Clinical Features Infantile Blount’s disease typically presents in the toddler (age 2-4 years) with bowed legs that have not resolved with normal walking development. The varus is more severe than physiological bowing, often combined with an internal tibial torsion that produces the characteristic intoeing gait. Examination shows the bow apex at the proximal tibial metaphysis rather than throughout the limb (in contrast to physiological bowing, which is more diffuse). Lateral thrust during stance phase of gait is characteristic and reflects the progressive medial physeal failure; the thrust may be subtle in early disease and obvious in advanced disease. Adolescent Blount’s disease presents with worsening genu varum in the adolescent, typically in a markedly obese patient. The unilateral or asymmetric pattern, the persistent obesity-related risk factors, and the older age at presentation are characteristic.

Differential Diagnosis The differential diagnosis is principally with physiological bowing, which is common in toddlers, typically bilateral and symmetric, peaks at 12-18 months of age, and resolves spontaneously by 2-3 years. The Drennan angle, the presence of unilateral or asymmetric disease, the failure to improve with growth, the lateral thrust on examination, and the radiographic features of medial metaphyseal beaking distinguish Blount’s disease. Other causes of genu varum that must be considered include rickets (vitamin D-deficient, vitamin D-resistant, hypophosphatemic, X-linked hypophosphatemic; the radiographic features of cupping and fraying of the metaphyses and the biochemical findings establish the diagnosis); skeletal dysplasias (Schmid metaphyseal chondrodysplasia produces varus with characteristic metaphyseal findings; spondylometaphyseal and other dysplasias should be considered); focal fibrocartilaginous dysplasia (a localized fibrocartilaginous lesion at the proximal medial tibial metaphysis producing localized varus); and post- traumatic deformity from prior physeal injury or osteomyelitis.

Treatment The treatment of infantile Blount’s disease is graded by Langenskiöld stage and patient age. Stages I-II (mild disease in the young child): Bracing with a knee-ankle-foot orthosis (KAFO) is the standard initial treatment if the child is younger than 3 years and has Langenskiöld I-II disease. The brace must be worn continuously (>23 hours daily) for at least a year, and compliance is challenging. Reported success rates are 50-80% in early stages. Failure of bracing or progression to Langenskiöld III or higher is an indication for surgery. Stages III-IV (moderate disease) or failure of bracing: Proximal tibial osteotomy is the standard surgical treatment. The osteotomy is typically performed with a valgus closing- wedge or opening-wedge cut, with derotation to address the internal tibial torsion, and is most commonly fixed with a small plate, multiple Steinmann pins with cast immobilization, or an external fixator. The principle is to slightly overcorrect the varus to 5-10° of valgus, since residual varus tendency from continued physeal asymmetry can return the bone to neutral over time. Hemiepiphysiodesis of the lateral proximal tibial physis with a single tension-band plate or staples is an alternative or adjunct to osteotomy, allowing continued growth on the medial side while restraining lateral growth — a “guided growth” approach that is particularly attractive in the older child with significant remaining growth. Stages V-VI (severe disease with physeal bar): Bar resection with interposition graft, combined with osteotomy to correct the existing deformity, is the standard for established bony bar. The reliability of bar resection is variable and depends on the size and location of the bar. Resection of less than 50% of the physeal surface with interposition of fat, methyl methacrylate, or other material can restore continued growth in some cases. For larger bars or repeated failure, completion of the physeal closure with epiphysiodesis of the opposite side and osteotomy is the alternative.

Adolescent Blount’s disease: Treatment is principally surgical because bracing is rarely effective at this age. Options include proximal tibial osteotomy (acute correction with internal fixation, or gradual correction with external fixation such as the Taylor Spatial Frame or Ilizarov method, which has the advantage of avoiding overcorrection and addressing complex multiplanar deformity), hemiepiphysiodesis if substantial growth remains, and combined procedures with distal femoral correction if the femoral component is significant. Complications and Long-Term Outcomes Complications of Blount’s disease and its treatment include: incomplete correction or recurrence of varus (relatively common, particularly with conservative treatment of advanced disease or with inadequate overcorrection at osteotomy); growth arrest of the proximal tibial physis; intra-articular deformity producing premature degenerative arthritis of the medial knee compartment (the principal long-term concern, with early adult arthritis often requiring total knee arthroplasty by the fourth or fifth decade); leg-length discrepancy from physeal arrest; compartment syndrome after osteotomy (particularly with acute corrections); and peroneal nerve injury (the nerve is at risk during proximal tibial osteotomy and should be protected, particularly with a fibular osteotomy that may be performed in conjunction).

Madelung’s Deformity

Definition and Epidemiology Madelung’s deformity is a developmental disorder of the distal radial physis characterized by premature partial closure of the ulnar-volar portion of the physis, producing progressive deformity of the wrist with shortening of the radius, increased volar and ulnar tilt of the distal radial articular surface, dorsal subluxation of the distal ulna, and pyramidal alignment of the carpal bones. The condition was named by Otto Madelung in 1878 and is one of the classical developmental wrist deformities. The condition is approximately four times more common in females than males. Presentation is typically in late childhood or early adolescence (age 8-14 years) with progressive deformity and pain, although mild cases may be discovered incidentally or in adulthood. Bilateral involvement is common (50-70%) but is often asymmetric. The condition may be sporadic (the “true” Madelung deformity) or part of the autosomal dominant Léri-Weill dyschondrosteosis syndrome (a mesomelic dwarfism caused by SHOX gene haploinsufficiency, which is also responsible for the more severe Langer mesomelic dysplasia in homozygous patients). A “pseudo-Madelung” deformity can also arise from trauma to the distal radial physis (post-traumatic Madelung-like deformity), from infection, or from tumor. Pathophysiology The underlying pathology is premature closure of the ulnar-volar quadrant of the distal radial physis, producing an asymmetric growth pattern in which the radial-dorsal portion of the physis continues to grow normally while the ulnar-volar portion does not. The

Vickers ligament — an abnormal, thickened palmar radiocarpal ligament extending from the distal volar radius to the lunate — is a characteristic finding, and is thought by some authors to be a primary tethering structure causing the deformity rather than a secondary consequence. The consequence of the asymmetric growth is the constellation of features: relative shortening of the radius compared with the ulna; increased volar and ulnar tilt of the distal radial articular surface; dorsal subluxation of the ulnar head; pyramidal “wedging” of the carpus with the lunate at the apex; widening of the distal radioulnar joint with potential separation; and ultimately limitation of forearm rotation (particularly supination) and wrist motion. Clinical Features Presentation is typically with progressive wrist deformity in late childhood or adolescence, pain (particularly with activity), limited supination, weakness, and cosmetic concerns. Examination reveals the characteristic wrist deformity with apparent ulnar prominence (from the dorsally subluxed ulnar head, the “bayonet” deformity), limited supination, and limited wrist motion. The deformity is sometimes confused with a healed distal radius fracture or with rheumatoid arthritis, both of which can produce similar superficial appearances. Imaging The standard imaging assessment is bilateral PA and lateral wrist radiographs. The classical features include: (1) Increased radial inclination (increased ulnar slope of the distal radial articular surface) — typically >30° (normal <30°). (2) Increased volar tilt of the distal radius — typically >25° (normal 11-15° volar). (3) Distal ulna dorsal subluxation — the distal ulna prominent dorsally relative to the distal radius. (4) Pyramidal carpus — the carpal bones arranged in an inverted-V configuration with the lunate at the apex. (5) Triangular distal radial epiphysis — characteristic shape from the asymmetric ossification. (6) Ulnar variance — positive ulnar variance from the relative radial shortening. (7) Increased radius-ulna distance at the distal radioulnar joint, with potential frank separation. The Cook-Crisco classification grades severity by these radiographic parameters. MRI is occasionally useful to demonstrate the Vickers ligament and to assess the cartilaginous components of the deformity, particularly in younger patients.

Treatment Treatment is tailored to severity, age, and skeletal maturity. Asymptomatic mild deformity: Observation is appropriate, with periodic clinical and radiographic follow-up. Symptomatic deformity in the skeletally immature patient: Vickers ligament release combined with physiolysis (removal of the prematurely closed portion of the physis) and dome osteotomy to correct the deformity is the procedure of choice in patients with substantial remaining growth. The principle is to release the tether of the Vickers ligament and to address the asymmetric growth. Symptomatic deformity at or near skeletal maturity: Corrective osteotomy of the distal radius (with or without ulnar shortening) is the standard surgical treatment. The radial osteotomy is typically a closing-wedge dorsoradial osteotomy or an opening-wedge osteotomy on the volar ulnar side, designed to correct the volar and ulnar tilt and restore a more normal distal radial articular orientation. Ulnar shortening osteotomy addresses the relative ulnar lengthening that contributes to the ulnar-sided wrist pain. Bone grafting is required for opening-wedge osteotomies. Distal ulna resection (Darrach procedure) or hemiresection arthroplasty (Bowers procedure) is reserved for cases with severe distal radioulnar joint disease. Severe deformity with established radioulnar joint disease: Sauve-Kapandji procedure (arthrodesis of the distal radioulnar joint with creation of a pseudarthrosis of the ulnar shaft) preserves an “ulnar head” appearance while restoring forearm rotation, and has been used successfully in selected cases. Outcomes The outcomes of surgical correction of Madelung deformity are generally good, with substantial improvement in pain, function, and cosmesis in most patients. The long-term concerns include progressive distal radioulnar joint degeneration (which may require later salvage procedures), recurrence of deformity (uncommon when the underlying physeal arrest has been addressed), and the development of carpal arthritis from the persistent abnormal joint mechanics.

Related Conditions

Léri-Weill Dyschondrosteosis Léri-Weill dyschondrosteosis is an autosomal dominant condition caused by SHOX gene haploinsufficiency producing mesomelic dwarfism (short forearms and legs with relatively preserved upper-arm and thigh length), Madelung deformity, and mild generalized short stature. Female patients are more severely affected than males. The orthopedic care addresses the Madelung deformity as described above and the associated lower-limb mesomelic shortening, which may require limb-lengthening procedures in selected cases.

Langer Mesomelic Dysplasia Langer mesomelic dysplasia is the homozygous form of SHOX gene mutation, producing severe mesomelic short stature with hypoplastic ulnae and fibulae, severe Madelung deformity, and associated features. The condition is rare and requires individualized multidisciplinary management.

Multiple Hereditary Exostoses Multiple hereditary exostoses (discussed in detail in the chapter on benign bone tumors) can produce a Madelung-like wrist deformity from involvement of the distal radius and ulna by exostoses, with growth disturbance and characteristic forearm shortening and bowing. The management combines exostosis excision with corrective osteotomies and, in severe cases, ulnar lengthening.

Summary and Take-Home Points

Blount’s disease and Madelung’s deformity, although affecting different parts of the skeleton, share the underlying theme of asymmetric physeal growth producing progressive angular deformity. Blount’s disease, a disorder of the medial proximal tibial physis, produces tibia vara with progression through six Langenskiöld stages; treatment is bracing for early disease in the young child, proximal tibial osteotomy or hemiepiphysiodesis for established disease, and bar resection with osteotomy for severe disease with physeal bridging. The associations with obesity, early walking, and African descent characterize the typical clinical presentation. Madelung’s deformity, a disorder of the ulnar-volar distal radial physis, produces the characteristic wrist deformity with volar and ulnar tilt, dorsal ulnar subluxation, and pyramidal carpus; the SHOX gene mutation in Léri-Weill dyschondrosteosis underlies many syndromic cases. Treatment combines Vickers ligament release and physiolysis in the immature patient and corrective osteotomy in the mature patient, with attention to the distal radioulnar joint and the associated ulnar variance. The unifying principles of recognition of asymmetric physeal growth, careful imaging assessment of the specific anatomy, and treatment tailored to the age, severity, and underlying condition produce successful outcomes in both disorders.