Authors’ Disclosure Statement: Dr. Kovar reports that he receives research support from a company or supplier as a principal investigator from DePuy Synthes, and other financial or material support from a company or supplier from OHK Medical Devices. Dr. Herzenberg reports that he is a consultant for Smith & Nephew, Ellipse Technologies, Orthofix, Orthopediatrics, and Wishbone Medical. He also reports that the following companies supported his institution's non-profit organization, which provides financial assistance to their patients: Stryker; Orthocare Solutions; Medevations; Bay Scribe; Nations Healthcare; and Chesapeake Surgical. The following companies supported Dr. Herzenberg’s institution's annual course for orthopedic surgeons: Smith & Nephew; BrainLab; Orthofix; DePuy Synthes; Stryker; Wright Medical Technology; Zimmer Biomet; and The MHE Coalition. Dr. Jauregui reports no actual or potential conflict of interest in relation to this article.
Dr. Kovar is an Orthopaedic Surgeon, Landesklinikum Baden-Mödling, Austria. Dr. Jauregui is an Orthopedic Surgery Resident, University of Maryland, Department of Orthopedics, Baltimore, Maryland. Dr. Herzenberg is Head of Pediatric Orthopedics, Sinai Hospital, and Director of the International Center for Limb Lengthening, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, Baltimore, Maryland.
Address correspondence to: John E. Herzenberg, MD, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, 2401 W. Belvedere Avenue, Baltimore, MD 21215 (tel, 410-601-9562; fax, 410-601-9575; email, jherzenberg@lifebridgehealth.org).
Am J Orthop. 2018;47(6). Copyright Frontline Medical Communications Inc. 2018. All rights reserved.
Florian M. Kovar, MD Julio J. Jauregui, MD John E. Herzenberg, MD . Accuracy of Distal Femoral Valgus Deformity Correction: Fixator-Assisted Nailing vs Fixator-Assisted Locked Plating. Am J Orthop.
June 12, 2018
TAKE-HOME POINTS
FAN and FALP are methods to improve the accuracy of long bone deformity correction.
Both methods include temporary stabilization of the osteotomy with an external fixator.
FALP is technically easier, since the external fixation pins do not have to be positioned out of the path of the nail, as in FAN.
Acute corrections in the distal femur from valgus to varus can stretch the peroneal nerve.
FAN and FALP are equivalent techniques for improving accuracy of deformity correction.
References
ABSTRACT
Fixator-assisted nailing (FAN) and fixator-assisted locked plating (FALP) are 2 techniques that can be used to correct distal femoral valgus deformities. The fixator aids in achieving an accurate adjustable initial reduction, which is then made permanent with either nail or plate insertion. FALP can be performed with the knee held in a neutral extended position, whereas FAN requires 30° to 90° of knee flexion to insert the nail, which may cause some alignment loss. We hypothesized that FAN may yield less accurate correction than FALP. Prospectively collected data of a consecutive cohort of patients who underwent valgus deformity femoral correction with FAN or FALP at a single institution over an 8-year period were retrospectively evaluated. Twenty extremities (18 patients) were treated using FAN (median follow-up, 5 years; range, 1-10 years), and 7 extremities (6 patients) were treated with FALP (median follow-up, 5 years; range, 1-8 years). In the FAN cohort, the mean preoperative and postoperative mechanical lateral distal femoral angles (mLDFAs) were 81° (range, 67°-86°) and 89° (range, 80°-100°), respectively (P = .009). In the FALP cohort, the mean preoperative and postoperative mLDFAs were 80° (range, 71°-87°) and 88° (range, 81°-94°), respectively (P < .001). Although the average mechanical axis deviation correction for the FALP group was greater than for the FAN group (32 mm and 27 mm, respectively), the difference was not significant (P = .66). Both methods of femoral deformity correction can be considered safe and effective. On the basis of our results, FAN and FALP are comparable in accuracy for deformity correction in the distal femur.
Multiple etiologies for distal femoral valgus deformity have been described in the literature.1-3 These can be congenital, developmental, secondary to lateral compartmental arthritis, or posttraumatic.4 If not corrected, femoral deformities alter the axial alignment and orientation of the joints, and may lead to early degenerative joint disease and abnormal leg kinematics.3,5 After correcting these deformities, the goal of treatment is to obtain anatomic distal femoral angles and neutral mechanical axis deviation (MAD), but without overcorrecting into varus. Numerous techniques to fix these deformities, such as progressive correction with external fixation or acute correction open reduction with internal fixation (ORIF), have been described.6 Modern external fixation allows for a gradual, adjustable, and more accurate correction but may produce discomfort and complications for patients.7-10 In contrast, ORIF may be more tolerable for the patient, but to achieve a precise correction, considerable technical skills and expertise are required.1,11-14
Two techniques used to correct these valgus femoral deformities in adults are fixator-assisted nailing (FAN) and fixator-assisted locked plating (FALP).1 FAN and FALP combine the advantage of external fixation (accuracy, adjustability) with the benefits of internal fixation (patient comfort), because the osteotomy and correction are performed with the guidance of a temporary external fixator and then permanently fixated by an intramedullary (IM) nail or a locking plate.1,8,11-13,15-18 Both techniques have the possibility to correct varus and valgus deformities, but whenever correcting sagittal plane angulation, the FAN technique may be more challenging. The paucity of studies available involving FAN and FALP do not lead to a conclusive preference of one technique over the other relative to the accuracy and success of correction.15,19,20
