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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 3  |  Issue : 1  |  Page : 52-56

Comparison of fixator-assisted plating versus fixator-assisted nailing for distal femoral osteotomy


Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, Cairo University, Giza, Egypt

Date of Web Publication15-Mar-2017

Correspondence Address:
Sherif Galal
Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, Cairo University, P.O. 11559, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jllr.jllr_25_16

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  Abstract 

Introduction: Fixator-assisted plating (FAP) and fixator-assisted nailing (FAN) have gained popularity recently in correcting deformities due to their advantage of combining the accuracy of deformity correction offered by external fixator (that is removed at the end of surgery) with the convenience of internal fixation for osteotomy fixation. The advantage of one method over the other is not yet clear and there are limited reviews in literature in this regard. We asked whether one technique has an advantage over the other as regards the ability to correct the deformity, blood loss, knee range, time to union, and complication rate. Methods: We identified 18 patients who underwent distal femoral osteotomies, 6 patients underwent FAP and 12 patients underwent FAN. We compared the accuracy of correction, duration of surgery, preoperative and postoperative knee range, and complications. Minimum follow-up was 13.4 months (6–18 months). Plates were used in skeletally immature patients or in skeletally mature patients with thin thighs, while nails were used in skeletally mature patients with big thighs. Results: We achieved the desired correction in all the 18 patients. Union was quicker with plates, but this could be attributed to the younger age of patients in that group. There was no statistically significant difference between both techniques that may point out that one method is superior to the other as regarding deformity correction (based on percentage improvement in mechanical axis deviation as compared preoperatively and at final follow-up). Preoperative and postoperative knee ranges were similar for both techniques and there was only one case of recurrence that had bone softening disease. Conclusion: Both techniques can be used to achieve correction with no statistically significant differences, and the choice between both techniques can be left to surgeons' or patients' discretion.
Level of Evidence: Level III, therapeutic study.

Keywords: Assisted, correction, deformity, fixator


How to cite this article:
Galal S. Comparison of fixator-assisted plating versus fixator-assisted nailing for distal femoral osteotomy. J Limb Lengthen Reconstr 2017;3:52-6

How to cite this URL:
Galal S. Comparison of fixator-assisted plating versus fixator-assisted nailing for distal femoral osteotomy. J Limb Lengthen Reconstr [serial online] 2017 [cited 2020 Sep 20];3:52-6. Available from: http://www.jlimblengthrecon.org/text.asp?2017/3/1/52/202212


  Introduction Top


Angular deformities of the distal femur can be acquired or developmental and are seen in patients with fracture malunion, metabolic disorders, osteoarthritis, and idiopathic processes. Limb deformities affect alignment of the lower limbs and cause abnormal mechanical forces across joints during ambulation, facilitating the progression of osteoarthritis.[1],[2]

Fixator-assisted plating (FAP)[3] and fixator-assisted nailing (FAN)[4] are both used to perform distal femoral osteotomy (DFO). Both have gained popularity recently in correcting deformities due to their advantage of combining the accuracy of deformity correction offered by external fixator (that is removed at the end of surgery) with the convenience of internal fixation for osteotomy fixation. The DFO with FAN is entirely percutaneous, and the DFO with FAP is a minimal invasive procedure, and in both, patients do not have to wear an external fixator.

The advantage of one method over the other is not yet clear and there are limited reviews in the literature in this regard.

We asked whether one technique has an advantage over the other as regards the ability to correct the deformity, blood loss, knee range of motion (ROM), time to union, and complication rate.


  Methods Top


Between February 2014 and February 2016, we identified 18 patients who underwent DFO, 6 patients underwent FAP and 12 patients underwent FAN.

The age of patients ranged from 11 to 42 years with a mean of 18.5 years. The BMI of the patients ranged from 20 to 34 with a mean of 25.52 kg/m 2. Indications for corrective DFO surgery using either of the two techniques were patients presenting with clinical deformity (varus or valgus) with the mechanical axis line of the lower limb passing more than 1 cm from the center of the knee joint with the distal femur as the source of the deformity as per Paley [5] method for deformity analysis.

If the mechanical axis line passes at the center of the knee joint, this would be considered as 0 MAD (i.e., normal). If it passes away from the center, the distance between the mechanical axis line and the knee center is measured in centimeters and is given a plus (+) sign if it passes medially or a negative (−) sign if it passes laterally. For example, MAD of + 6 cm means genu varum deformity where the mechanical axis line passes 6 cm medial to the knee center and MAD of -4 cm means genu valgum deformity where the mechanical axis line passes 4 cm lateral to the knee center. This method of quantifying for MAD was adopted by Paley,[5] which the author believes is more accurate than older methods in which the knee joint width was divided into zones; which would not be applicable in patients where the mechanical axis line passes totally away from the knee joint line.

The percentage improvement in MAD was calculated by comparing the MAD preoperatively and at final follow-up, for example, a patient with a preoperative MAD of + 5 cm (genu varum) who has a MAD of +1 cm at the final follow-up achieved 80% (4 out of the 5 cm) improvement in his/her MAD.

Since all patients had their center of rotation of angulation (CORA) close to the knee joint line, even a small angle of deformity produced significant MAD. Thus, small angular improvements will yield significant MAD improvements which the author thought it would be easier to evaluate statistically than small angular improvements.

The mechanical lateral distal femoral angle (mLDFA) of the deformed side was compared to the normal side in unilateral cases or compared to population average value of 87°.

Long Leg films were obtained preoperatively, postoperatively, and at final follow-up. The deformity analysis was made as per the method described by Paley.[5]

Plates were used in skeletally immature patients or in skeletally mature patients with thin thighs while nails were used in skeletally mature patients with big thighs.

Plates used were either locked anatomical distal femoral plates or locked dynamic condylar screw plates. All nails used were regular retrograde femoral trauma nails.

FAN was performed as per Paley [4] method while FAP was performed as per Eidelman [6] method.

The proximal pins are inserted at the level of the calcar (to be proximal to the nail), they are perpendicular to the anatomic axis in the anteroposterior view.

The distal pins are inserted from lateral anteriorly in the femoral condyles to allow nail passage. They are perpendicular to the anatomic axis of the lower femur and not parallel to the joint.

The proximal and distal set of the pins are inserted orthogonal to the proximal and distal fragments in the frontal plane at an angle equal to magnitude of deformity, thus when the two sets of pins are made parallel to each other after the osteotomy is done, the deformity will be corrected.

Nails were inserted through a medial para-patellar approach using a k-wire as a guide for the starting reamer to open the medulla, followed by the regular guide wire for the reamer. Plates were inserted using a lateral submuscular approach.

Osteotomy was done using the multiple drill hole technique and completed with an osteotome.

An angulation translation osteotomy was done in all cases; as the CORA [5] was usually close to the joint, the author moved the osteotomy site a little proximal to the CORA site, thus making osteotomy site translation mandatory according to osteotomy rules advocated by Paley [5] This gave two benefits, the first was providing bigger lower segment (below the osteotomy) making more room for screw fixation or nail passage in that segment. ([Figure 1] three locking screws in that fragment, hence enhancing fixation stability). The second benefit was invagination of osteotomy edges, thus providing more support osteotomy. [Figure 1] shows the medial edge of the lower fragment wedged into the lower end of the upper fragment, thus improving bone contact at osteotomy site and avoiding the need for grafting, keeping the whole procedure minimally invasive.
Figure 1: Pre- and post-operative long leg standing X-ray for case example number 1

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Alignment was checked intraoperatively using the cautery cord test.

We compared the accuracy of correction (based on correction of the MAD and magnitude of angular deformity), duration of surgery, preoperative and postoperative knee ROM, blood loss, and complications. Average follow-up after complete union was 13.4 months (6–18 months).

Monthly radiographs were done in the follow-up period to check for bone healing. Partial weightbearing was allowed by 4–6 weeks, and full weightbearing was allowed when full union (as evident by disappearance of fracture line on radiography) was achieved. Surgery for patients with bilateral deformities was done in two separate settings with 3–4 months' interval [Table 1].
Table 1: Summarizing patients' data

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  Results Top


The author was able to achieve alignment in which the mechanical axis of the lower limb passed within 1 cm of the center of the knee joint line in all the 18 patients.

FAN was possible in cases where the apex of deformity was metaphyseal. Nails could be inserted in the wide metaphysis with blocking screws to limit toggle and allow some translation as well. Time to union was 12 weeks (8–16). Union was faster with plates, but this may be attributed to the younger age of patients in that group (most of them were skeletally immature).

Postoperative blood transfusion was needed in four of the eight patients who underwent FAP, but none of the patients who underwent FAN. All patients who underwent FAP reported hardware irritation but none required removal. Pre- and post-operative knee ROMs were similar for both techniques.

[Table 2] shows comparison of improvement in MAD. No statistically significant difference was noted (P = 0.118).
Table 2 Comparison of two methods regarding improvement in mechanical axis deviation

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One case of recurrence had bone softening disease with metaphyseal apex of the deformity in which intramedullary nail was used to span the whole length of the bone and reduce the chance of recurrence. This patient had hyperparathyroidism for which she underwent subtotal parathyroidectomy before deformity correction. She had a multi-apical deformity with one apex being diaphyseal and the other apex being metaphyseal. Two osteotomies were done, one at each apex and a nail was inserted. Correction was achieved intraoperatively and healing occurred uneventfully. However, recurrence occurred later when patient started full weightbearing. The author believes that the recurrence was due to early surgery before full correction of the underlying metabolic condition. No revision surgery was done as per the patient's preference.

Two cases showed superficial surgical wound site infection that did not require debridement or implant removal and resolved completely by a course of IV antibiotics and wound daily dressing. No other major complications were noted.

[Figure 1],[Figure 2],[Figure 3],[Figure 4] show some clinical examples, some of the cases show corrected tibiae as well, two cases among the FAN group and two cases among the FAP group. Cases with concurrent tibial deformity were included only if full correction was achieved for the tibial deformity so as not to interfere with analysis of femoral deformity.{Figure 1}
Figure 2: Pre- and post-operative long leg standing X-ray for case example number 2

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Figure 3: Pre- and post-operative long leg standing X-ray for case example number 3

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Figure 4: Pre- and post-operative long leg standing X-ray for case example number 4

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  Discussion Top


Correction of angular deformities around the knee has always been a debatable subject. Many methods of fixation were used and compared in literature for addressing such deformities. Surgeons aim for achieving the maximum possible patient satisfaction without compromising the accuracy of correction or rigidity of fixation.

External fixators allow for accurate correction with minimal incisions, but prefer bulky constructs for several months.

Using internal fixation usually gives higer levels of patient comfort and satisfaction and is chosen by many surgeons.

FAP and FAN techniques represent a breakthrough in deformity correction because they combine the advantages of internal and external fixation without significant complications. Despite being new, they hold promise with good results reported so far.

This posed a very important question, is fixator-assisted internal fixation methods (namely FAP and FAN) as effective as the external fixation in achieving correction and holding reduction? Rozbruch [7] reviewed 34 deformed limbs in 26 patients who underwent a DFO. Some patients had their osteotomies fixed by a unilateral fixator while others with a locking plate. On comparing both groups, they concluded that both techniques were equally effective.

Eralp [8] carried out a prospective study to answer the same query, but in contrast to the one of Rozbruch,[3] this study included femoral as well as tibial deformities in a rachitic population. Some of the patients had their osteotomies fixed by an Ilizarov frame while others by an intramedullary nail. We too conclude that both techniques are equally effective as regards the accuracy of correction but highlight the better patient satisfaction in the internal fixation group compared to the external fixation group.

In 2012, Eidelman [6] did a prospective case series that included six patients (seven femurs) with distal femoral valgus. The FAP technique was used for all patients. The authors concluded that the FAP technique has advantages over external fixation and intramedullary nail. They added that this method may be performed by minimally invasive technique with minimal morbidity.

Till now, there are no available studies recommending one technique over the other. In this study, the author wanted to answer this question and found that both groups showed similar results except the time for union which was shorter in the FAP group (which could be attributed to the young age of this group being skeletally immature).


  Conclusion Top


Both techniques can be used to achieve correction with no statistically significant differences, and the choice between both techniques can be left to surgeons' or patients' discretion though the risk of blood transfusion and hardware irritation was higher with FAP.

The author thinks that FAN carries some advantage in patients' convenience, especially that it can still be used for metaphyseal deformities. A serious limitation to the study is that the two groups are not matched and that the numbers are not significant to draw conclusions. More studies which include matched groups with a longer follow-up are needed before a conclusion about which technique has an advantage over the other.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Tetsworth K, Paley D. Malalignment and degenerative arthropathy. Orthop Clin North Am 1994;25:367-77.  Back to cited text no. 1
    
2.
Kettelkamp DB, Hillberry BM, Murrish DE, Heck DA. Degenerative arthritis of the knee secondary to fracture malunion. Clin Orthop Relat Res 1988;234:159-69.  Back to cited text no. 2
    
3.
Rozbruch SR. Fixator-assisted plating of limb deformities. Oper Tech Orthop 2011;21:174-9.  Back to cited text no. 3
    
4.
Paley D, Herzenberg JE, Bor N. Fixator-assisted nailing of femoral and tibial deformities. Tech Orthop 1997;12:12:260-275.   Back to cited text no. 4
    
5.
Paley D, Herzenberg JE, Tetsworth K, McKie J, Bhave A. Deformity planning for frontal and sagittal plane corrective osteotomies. Orthop Clin North Am 1994;25:425-65.  Back to cited text no. 5
    
6.
Eidelman M, Keren Y, Norman D. Correction of distal femoral valgus deformities in adolescents and young adults using minimally invasive fixator-assisted locking plating (FALP). J Pediatr Orthop B 2012;21:558-62.  Back to cited text no. 6
    
7.
Seah KT, Shafi R, Fragomen AT, Rozbruch SR. Distal femoral osteotomy: Is internal fixation better than external? Clin Orthop Relat Res 2011;469:2003-11.  Back to cited text no. 7
    
8.
Eralp L, Kocaoglu M, Toker B, Balci HI, Awad A. Comparison of fixator-assisted nailing versus circular external fixator for bone realignment of lower extremity angular deformities in rickets disease. Arch Orthop Trauma Surg 2011;131:581-9.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2]



 

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