Background: This study aimed to determine the recurrence rate in infantile Blount disease (IBD) in a cohort of patients treated with a tibial osteotomy; and also to identify which factors were associated with recurrence. Methods: We reviewed the records of 20 patients, under the age of 7 years, with IBD (35 involved extremities) treated by proximal tibial realignment osteotomy to physiological valgus at a single institution over 4 years. We then analyzed the data to determine the rate of recurrence and identify the risk factors for recurrence. Results: The mean age of the included patients was 4.2 years (range, 2 to 6 y). We observed a recurrence rate of 40% (n=14) at a mean follow-up of 42 months (range, 21 to 72 mo). Knee instability [odds ratios OR, 6.6; 95% confidence interval (CI), 2.0-22.2], Langenskiöld stage (OR, 6.3; 95% CI, 2.0-19.4), and severity of the deformity, as measured by medial physeal slope (MPS) (OR, 1.2; 95% CI, 1.1-1.4), were associated with recurrence. On multiple logistic regression analysis, MPS remained the most relevant predictor of recurrence. Receiver operating curve analysis showed that an MPS ≥60 degrees predicted recurrence with a sensitivity of 79% and specificity of 95% (area under the curve=0.925). Postoperatively, increased varus alignment on weight-bearing as measured by the tibio-femoral angle was indicative of knee instability and associated with increased odds of recurrence (OR, 1.5; 95% CI, 1.1-1.9; P=0.004). Conclusions: We observed a recurrence rate of 40% in children with IBD under 7 years treated with acute correction to a tibio-femoral angle of 5 to 10 degrees valgus through a dome proximal tibial osteotomy. Knee instability, Langenskiöld stage, and MPS were associated with recurrence. Cases with an MPS ≥60 degrees seem to be particularly at risk for recurrence. Further research is needed to validate these findings. Level of Evidence: Level IV.

Background: Late-presenting or recurrent infantile Blount disease (IBD) is characterized by knee instability because of medial tibial plateau depression, multiplanar proximal tibial deformity, and potential distal femoral deformity. The surgical treatment strategy includes medial elevation osteotomy to stabilize the knee, together with proximal tibial osteotomy to correct alignment, and lateral epiphysiodesis to prevent a recurrence. This study’s primary aim was to describe the clinical outcomes of medial elevation osteotomy for the management of late-presenting and recurrent IBD. Methods: The authors reviewed the records of 48 children (64 limbs) who had medial elevation osteotomies and lateral epiphysiodesis, combined with proximal tibial realignment in 78% (50/64) of cases in the same setting. IBD was bilateral in 33% (16/48), 77% (37/48) were female individuals, and 42% (20/48) were obese. Results: The mean age at surgery was 8.6 years (SD, 1.6; range, 5.8 to 12.8). The mean preoperative tibiofemoral angle (TFA) was 28±11 degrees (8 to 55 degrees), and the mean angle of depression of the medial plateau (ADMP) was 49±8 degrees (26 to 65 degrees). Distal femoral valgus was present in 27% (17/62) and varus in 10% (6/62) children. At a median follow-up of 3.2 years (range, 1 to 6.2 y), the median TFA was 1-degree valgus (interquartile range, 7-degree varus to 5-degree valgus), whereas the ADMP was corrected to 25±8 degrees (8 to 45 degrees). Obesity was associated with more severe deformity as measured by TFA (P<0.001) but did not affect the extent of medial plateau depression (P=0.113). The good or excellent alignment was achieved in 75% (47/63) limbs. Obesity was associated with an increased risk of recurrence [odds ratio (OR), 5.21; 95% CI, 1.26-21.63; P=0.023]. Age at the surgery or previous surgery was not associated with recurrence (OR, 1.29; 95% CI, 0.88-1.88; P=0.195 and OR, 1.22; 95% CI, 0.36-4.17; P=0.746). Obesity and residual instability were associated with an increased risk of poor alignment at the latest follow-up (OR, 3.24; 95% CI, 1.02-10.31; P=0.047 and OR, 1.21; 95% CI, 1.05-1.40; P=0.008). Conclusion: Late-presenting or recurrent IBD is a surgical challenge. Obesity is associated with more severe deformity. Medial elevation osteotomy combined with lateral proximal tibial epiphysiodesis and metaphyseal tibial realignment osteotomy will result in restoration of lower limb alignment in a high proportion of cases. The recurrent deformity may be the result of failed epiphysiodesis. Obesity and residual instability are associated with an increased risk of poor alignment. Although complications are rare, surgical measures to decrease risk should be followed. Level of Evidence: Level IV.

Corresponding author: A Vorster (vorster@sun.ac.za)Background. A relatively high frequency of autosomal recessively inherited osteogenesis imperfecta (OI) type 3 (OI-3) is present in the indigenous black southern African population. Affected persons may be severely handicapped as a result of frequent fractures, progressive deformity of the tubular bones and spinal malalignment. Objective. To delineate the molecular basis for the condition. Methods. Molecular investigations were performed on 91 affected persons from seven diverse ethnolinguistic groups in this population. Results. Following polymerase chain reaction amplification and direct cycle sequencing, FKBP10 mutations were identified in 45.1% (41/91) OI-3-affected persons. The homozygous FKBP10 c.831dupC frameshift mutation was confirmed in 35 affected individuals in the study cohort. Haplotype analysis suggests that this mutation is identical among these OI-3-affected persons by descent, thereby confirming that they had a common ancestor. Compound heterozygosity of this founder mutation was observed, in combination with three different deleterious FKBP10 mutations, in six additional persons in the cohort. Four of these individuals had the c.831delC mutation. Conclusion. The burden of the disorder, both in frequency and severity, warrants the establishment of a dedicated service for molecular diagnostic confirmation and genetic management of persons and families with OI in southern Africa.

Infantile Blount's disease results in multi-planar proximal tibial deformity consisting of varus, procurvatum, internal rotation and shortening. The deformity is attributed to disordered growth of the posteromedial proximal tibial physis. The aetiology is multifactorial. It is associated with childhood obesity and African ethnicity. The ability to differentiate between infantile Blount's disease and physiological bowing depends on the findings of focused clinical examination, X-ray appearance, tibial metaphyseal-diaphyseal angle and tibial epiphyseal-metaphyseal angle. The gold standard of treatment is proximal tibial metaphyseal corrective osteotomy before the age of 4 years. The limb should be realigned to physiological valgus. The recurrence rate after realignment osteotomy is high. Recurrence is associated with age at osteotomy, obesity, higher Langenskiöld stage and medial physeal slope >60°. The surgical management of severe, recurrent or neglected infantile Blount's disease is challenging. Comprehensive clinical examination and multi-planar deformity analysis with standing long leg X-rays are essential to identify all aspects of the deformity. Distal femur coronal malalignment and significant rotational deformity should be excluded. Knee instability due to intra-articular deformity should be corrected by elevation of the medial tibial plateau. Lateral epiphysiodesis should be done at the same time as medial plateau elevation and when medial growth arrest is certain to prevent recurrence. Level of evidence: Level 5 Keywords: Blount's disease, tibia vara, genu varum, recurrence, obesity