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

DISCUSSION

The goal of this study was to compare the accuracy of deformity corrections achieved with either FAN or FALP. A number of authors have described results after deformity correction with several plating and nailing techniques; however, the information derived from comparing these 2 techniques is limited. We hypothesized that FALP would be more accurate, because less mobilization during fixation is required. However, we found no significant differences between these 2 techniques.

This study has several limitations. First, the small size of our cohort had to be further reduced owing to limited data; nevertheless, this pathology and the treatment methods used are not commonly performed, which make this cohort 1 of the largest of its type described in the literature. Also, the procedures were performed by multiple surgeons in a population with a wide age range, creating multiple additional variables that complicate the comparison of the sole differences between FAN and FALP. However, owing to these variables, the generalizability of this study may be increased, and similar outcomes can potentially be obtained by other institutions/surgeons. In addition, the variability of our follow-up period is another limitation; however, these patients were all assessed until bony union after skeletal maturity was achieved. Hence, the development of additional deformity is not expected. The lack of clinical outcome with a standardized questionnaire may also be seen as a limitation. However, because the purpose of our study was to assess both surgeries in terms of their ability to achieve angular correction, the addition of patient-reported outcomes may have increased the variability of our data.

The foremost objective in valgus deformity correction is to establish joint orientation angles within anatomic range to prevent overloading of the lateral joint and thereby prevent lateral compartmental osteoarthritis.^2,20,27-29 There are 2 categories of fixation: internal and external. With FAN and FALP, we strive to have the adjustability and accuracy of external fixation with the comfort (for the patient) of internal fixation. Accurate osteotomy correction requires an accurate preoperative analysis and osteotomy close to the apex of the deformity.^16,21,30-33 The most commonly used osteotomy techniques are drill-hole,³¹ focal dome,³⁴ rotation, and open- or closed-wedge osteotomies.^35,36 After the osteotomy, the resultant correction has to be stabilized. In recent years, the popularity of plates instead of an IM nail for internal fixation has been driven by the rapid development of low contact locking plates.^{16,19,26,30,37-40}

There are certain advantages of using FAN over FALP. In older patients who may require a subsequent total knee arthroplasty (TKA), the midline incision used for retrograde FAN technique is identical to that made for TKA. In contrast, in a younger and more active population, with a longer life expectancy, the extra-articular FALP approach has the advantage of not violating the knee joint. In addition, locking plates may achieve a more rigid fixation than IM nails; however, the stability of IM nails can be augmented with blocking screws.

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