Magnetic resonance imaging of the growth plate in late-onset tibia vara

Abstract

We used Magnetic resonance imaging (MRI) in five patients (six knees), mean age 13.2 (12-15) years, with late-onset tibia vara (Blount's disease), to study the growth plate and its abnormalities. The MRI study was classified for severity of disease and compared with a radiographic classification. In severely involved knees, MRI indicated severe growth-plate changes on both sides of the knee joint. Widening in the entire proximal tibial growth plate, involvement of the distal femoral growth plate, as well as cartilage invaginations into the metaphyses, were constant findings. Three knees were treated operatively with oblique tibial osteotomy and three with lateral hemiepiphysiodesis. Two severely involved patients treated initially with hemiepiphysiodesis required additional surgery. The three patients with mild disease treated with tibial osteotomy had good clinical and functional results. This study suggests that extensive growth-plate changes in severe, late-onset tibia vara preclude successful treatment by tibial hemiepiphysiodesis. In addition, oblique osteotomy, which was successful in mild cases, was problematic in severe cases.Résumé Nous avons utilisé la résonance magnétique nucléaire chez cinq malades (six genoux), d'âge moyen 13,2 (12-15) années présentant une maladie de Blount (Tibia Vara avec début tardif) pour étudier le cartilage de conjugaison et ses caractères anormaux. L'étude IRM a été classée selon la sévérité de la maladie et comparé avec une classification radiographique. Dans les genou altérés sévèrement l' IRM a montré des modifications sévéres du cartilage de conjugaison des deux côtés du genou. L'élargissement du cartilage de conjugaison tibial proximal, l'atteinte du cartilage distal fémoral, aussi bien que des invaginations du cartilage dans les métaphyses étaient des constatations constantes. Les malades ont été traités chirurgicalement par une osté-otomies tibiale oblique dans trois genoux ou une hémiépiphysiodèse pour trois genoux. Les deux malades sévèrement impliqués, initialement traités avec une hémiépiphysiodèse, ont nécessité une chirurgie supplé-mentaire. Trois patients avec une maladie peu évoluée traitée par ostéotomie tibiale avaient un bon résultat clinique et fonctionnel. Cette étude suggère que les modifications du cartilage de conjugaison dans le Tibia Vara sévère avec début tardif empêchent le traitement par hémiépiphysiodèse tibiale. De plus, l'ostéotomie oblique qui était utile dans les cas discrets était problémati-que dans les cas sévères.

An MRI-based technique for assessment of lower extremity deformities—reproducibility, accuracy, and clinical application

“…When applying MRI, no radiation exposure is required. However, until now, MRI measurements have only been introduced into the diagnosis of leg deformities for femoral anteversion in pediatric patients with femoral [11] and growth-plate changes in tibia vara prior to oblique osteotomy or tibial hemiepiphysiodesis [12]. These applications are based on axial MRI images at the center of the main magnetic field and, hence, the gradient fields used for image reconstruction.…”

“…However, it has not yet been established for preoperative planning of corrective surgery, even though first experiences in the comparison of radiography, CT, and MRI on cadaveric femurs have been published [10]. Currently, MRI is part of the diagnostic procedure only in pediatric patients with femoral anteversion prior to rotation osteotomies [11] and growth-plate changes in tibia vara prior to oblique osteotomy or tibial hemiepiphysiodesis [12]. The technical limitations are that the field of view (FoV) of typical clinical scanners does not allow imaging of objects larger than 50 cm without table movement and that conventional high-field (> 1 Tesla) MRI systems cannot simulate the effect of full weight bearing on the limb axis because of the supine imaging position.…”

Do we need to do overcorrection in Blount’s disease?

“…Ferriter and Shapiro [9] found a clear difference, such that there was a recurrence rate of 76 % in limbs operated initially at age older than 4.5 years versus 31 % recurrence rate before 4.5 years. Many reports concluded that (a) operative treatment should be performed before the age of four years on patients with progressive clinical and radiographic evidence of Blount disease, (b) surgical correction should be performed when radiographic stage shows the patient had Blount disease corresponding to Langenskiöld stage I or II, (c) a single corrective osteotomy performed early on the affected limb could result in permanent correction which could significantly decrease the incidence of a symptomatic and painful knee at maturity, and (d) failure to correct the tibia vara early will result in permanent physeal damage and development of degenerative intra-articular knee pathology, including meniscal tears and degenerative articular cartilage changes [12,[14][15][16][17].…”

The Lower Extremity: Acquired Disorders

“…There is invagination of cartilage into the tibial and femoral metaphyses. Bone may bridge the physis [ 27 ] (Fig. 14.26 ).…”