Recurrent or late presenting Tibia Vara is a complex clinical problem. In addition to the multiplanar deformity the disorder is often accompanied by obesity. Simple re-alignment osteotomy with acute correction is effective early in the disease. Its use in recurrent or severe deformities is limited by geometric constraints (mechanical axis translation), difficult fixation and the risk of compartment syndrome. Gradual correction with external fixation devices is a well-accepted technique in these cases. It has been shown to obtain accurate correction and provides stable fixation. This allows early weight bearing which facilitate consolidation and rehabilitation. Hexapod fixators are technically less demanding than standard Ilizarov techniques. The TLHex is a relatively new hexapod fixator available in South Africa. Frame pre-assembly allows easier mounting on a limb with complex deformity. The software allows for non-orthogonal mounting, which simplifies frame-mounting assessment. Double telescoping struts allow greater strut excursion and the outside mounting of struts on the ring increases mounting options for fixation elements.
This is the first report on its use in Blount's disease.
Evaluation of the result of gradual correction with the TLHex external fixator in Blount's disease in terms accuracy of correction, union and complications. Illustration of key hardware and software features.
A retrospective chart and X-ray review of 7 patients (9 legs) treated by gradual correction with the TLHex external fixator was performed. The degree of correction of varus and procurvatum was assessed on pre-operative and post-correction X-rays. Internal rotation deformity correction was assessed clinically. Complications such as neurovascular compromise, minor and major pin tract infection and hardware complications were documented. The pre-operative planning, surgical technique and post-operative treatment protocol is reviewed.
Mean varus was corrected from 21° (17° to 45°) to 1°(−2° to 4°). Mean procurvatum was corrected from 8° (0° to 25°) to 0° (0° to 8°). Internal rotation was corrected to between 5° to 10° of external rotation in all patients. The mean time in the frame was 112 days.
Three patients needed one additional program to correct residual deformity (one over-corrected coronal aligment, one under-corrected saggital alignment and one rotational over-correction). Three patients required oral antibiotics for minor pin tract infection. One patient required intravenous antibiotics and wire removal for major pin tract infection.
One patient required frame adjustment after correction for soft tissue impingement. One strut loosened after consolidation prior to frame removal.
Gradual correction of Tibia Vara with the TLHex external fixator is a safe and effective treatment method.