Accuracy of Distal Femoral Valgus Deformity Correction: Fixator-Assisted Nailing vs Fixator-Assisted Locked Plating

In 20 patients, including children and young adults, with frontal and sagittal plane deformities, Marangoz and colleagues⁷ reported on correction of valgus, varus, and procurvatum deformities using a Taylor Spatial Frame (TSF). Successful correction of severe deformities was achieved gradually with the TSF, resulting in a postoperative deformity (valgus group) of mLDFA 88.9° (range, 85°-95°).⁷ In a more recent study, Bar-On and colleagues¹⁵ described a series of 11 patients (18 segments) with corrective lower limb osteotomies in which all were corrected to within 2° of the planned range. Similarly, Gugenheim and Brinker²⁰ described the use of the FAN technique to correct distal varus and valgus deformities in 14 femora. The final mean mLDFA and MAD in the valgus group were 89° (range, 88°-90°) and 5 mm (range, 0-14 mm medial), respectively.

In their comparative study, Seah and colleagues¹¹ described monolateral frame vs FALP deformity correction in a series of 34 extremities (26 patients) that required distal femoral osteotomy. No differences related to knee range of motion or the ability to correct the deformity between internal and external fixation were reported (P > .05). Similarly, Eidelman and colleagues¹ evaluated the outcomes of 6 patients (7 procedures) who underwent surgery performed with the FALP technique for distal femoral valgus deformity. They concluded that this technique is minimally invasive and can provide a precise deformity correction with minimal morbidity.

Other methods of fixation while performing FAN have been described by Jasiewicz and colleagues,²² who evaluated possible differences between the classic Ilizarov device and monolateral fixators in 19 femoral lengthening procedures. The authors concluded that there is no difference between concerning complication rate and treatment time. The use of FAN has also been described in patients with metabolic disease who required deformity correction. In this regard, Kocaoglu and colleagues¹² described the use of a monolateral external fixator in combination with an IM nail in a series of 17 patients with metabolic bone disease. The authors concluded that the use of the IM nail prevented recurrence of deformity and refracture.¹² Kocaoglu and colleagues¹⁴ also published a series of 25 patients treated with the FAN and LON (lengthening over a nail) technique for lengthening and deformity correction. The mean MAD improved from 33.9 mm to11.3 mm (range, 0-30 mm). In contrast, Erlap and colleagues¹³ compared FAN with circular external fixator for bone realignment of the lower extremity for deformities in patients with rickets. Although no significant difference was found between both groups, FAN was shown to be accurate and to provide great comfort to patients, and it also shortened the total treatment time.¹³ Finally, the advent of newer technologies could also provide alternatives for correcting valgus deformities. For example, Saragaglia and Chedal-Bornu⁶ performed 29 computer-assisted valgus knees osteotomies (27 patients) and reported that the goal hip-knee angle was achieved in 86% of patients and that the goal MPTA was achieved in 100% of patients.⁶

CONCLUSION

Both the FALP and FAN methods of femoral deformity correction are safe and effective surgical techniques. In our opinion, the advantages of the FALP technique result from the easy lateral surgical approach under medial external fixation and stabilization of the osteotomy without bending the knee. Ultimately, the decision to use FAN may be influenced by the surgeon’s perception of the potential need for future TKA. In such cases, a midline anterior approach with nailing is very compatible with subsequent TKA. The surgeon’s experience and preference, while keeping in mind the patient’s predilection, will play an important role in the decision-making process. Larger prospective clinical trials with larger cohorts have to be conducted to confirm our findings.