S-design osteotomy and internal fixation for multiplanar and acute correction of deformity in infantile Blount's disease - preliminary results from single centre series.

PURPOSE: This is a preliminary study with short-term follow up to determine the safety and efficacy of the S-design osteotomy and internal fixation for acute varus and rotational correction technique in infantile Blount's disease.

METHODS

We performed a retrospective series in our institutional hospital. An S-design osteotomy for multiplanar, acute correction followed by internal fixation was performed for Blount's disease patients. Effectiveness was measured by comparing pre-and post-operative tibiofemoral angle (TFA) and metaphyseal-diaphyseal angle (MDA). Safety was determined by the number of neurological deficits and compartment syndromes occurred post operatively. Functional outcome was assessed using the Lower Extremity Functional Scale (LEFS). All patients underwent a one-year follow-up after surgery.

RESULTS

Nineteen patients (total of 31 extremities) were included in this study and classified into TFA less than 40 degree (group A) and more than 40 degree (group B). No neurological deficits nor compartment syndrome occured in either group. Regardless the severity of pre-operative deformity, both groups achieved significant corrections. Post operatively there was no significant difference in TFA in Group A and Group B (1.70 and 3.00 respectively, with p value of 0.147) and MDA (4,60 and 6,0 respectively, with p value of 0.327). This indicated there was no correlation between preoperative deformity and postoperative results. LEFS score of group A (73.85 ± 2.73) and Group B (73.85 ± 2.73) showed equally good results in both groups (p = 0.293).

CONCLUSION

This preliminary study with short-term follow up suggested that the S-design osteotomy effectively corrected internal rotation and varus while aiding limb length. The correction of internal rotation is accomodated by performing box osteotomy between the two horizontal (proximal and distal) lines of osteotomy, with safe and effective results. Acute correction is a safe and effective strategy for severe Blount's disease. Longer-term follow-up is awaited.

LEVEL OF EVIDENCE: V.