Articulated lengthening fixation apparatus (ALFA) for the management of gap non-union of distal femur: Initial experience on a new technique.

PURPOSE: Distal femur non-union is difficult to deal with because of limited or no bone stock left for holding pins. Also, knee range of motion is a major concern in case of distal femur non-union to deal with. ALFA is a new modality of definitive external fixator with limited literatures. This paper aims to present the series of cases of gap non-union of the distal femur managed with an ALFA fixator and their outcome as an initial experience on a new device.

METHODS: Eight patients of gap non-union distal femurs where the ALFA fixator application was done between January 2022 to June 2022 were evaluated. Patients with intra-operative bone gap <5 cm were acutely docked and >5 cm were left as it is as a bon gap and gradual distraction was done to achieve bone gap length and limb length discrepancy. Patients were assessed for functional, radiological, and clinical outcomes, at the time of surgery, completion of distraction, and completion of consolidation. The scores from our study were compared with the Ilizarov and mono-lateral fixator with the available data.

RESULTS: Eight patients managed with ALFA fixator had mean age of 32.12 ± 6.82 years. The mean limb length discrepancy at the time of operation was 5.25 ± 3.11 cm, with Intra-operative bone gap of 4.68 ± 3.47 cm where 5 patients managed with acute docking and 3 patient managed with leaving the bone-gap. The mean regenerate gained after distraction was 9 ± 4.63 cm at the mean distraction duration of 113.37 ± 67.34 days. The mean time of removal of the fixator (n = 5), was 203 ± 111 days, and the mean external fixator index, days/cm (n = 5) was 34 days/cm. The number of complications per patient was 0.25 per patient. The Mean residual LLD was, 0.43 ± 0.58, with significant improvement of Limb Length compared to pre-operative LLD with a p-value of 0.0014.

CONCLUSION: ALFA fixator for gap non-union as an alternative to Ilizarov, and LRS provides adequate distraction osteogenesis, less neurovascular complication due to pins, better patient tolerability, and user-friendly distraction of the distal femur with preserved knee range of motion.

LEVEL OF EVIDENCE: III.