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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 57  |  Issue : 1  |  Page : 9-14

Correction of multiplanar deformities around the knee with monolateral external fixator


1 Department of Orthopedic Surgery, Helwan University, Helwan, Egypt
2 Department of Orthopedic Surgery, 6 October Health Insurance Hospital, Giza, Egypt

Date of Submission28-Oct-2021
Date of Decision01-Dec-2021
Date of Acceptance02-Jan-2021
Date of Web Publication31-May-2022

Correspondence Address:
MD Mohamed Hussein Fadel
Vila 116 B Evergreen Compound Hadaek October, Department of Orthopedic Surgery, Helwan University, Helwan
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/eoj.eoj_120_21

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  Abstract 


Introduction Angular deformities around the knee are common during childhood and most cases are a variation in the normal growth pattern. Uncorrected deformities change the biomechanics by disturbing stress distribution on the knee joint weight-bearing surface. Monolateral external fixator with osteotomy has shown better results being simple, and offers accurate correction, a low complication rate, the ability to correct valgus, varus, and rotational deformities, with early mobilization of the patient.
Patient and methods A multicenter study case series prospective study was conducted from January 2020 to January 2021. A total of 30 patients with coronal plane deformities were included in the study. Of them, 15 patients (all cases were unilateral, 9 left limbs and 6 right limbs) presented with genu valgum with an age range between 10 and 16 years, and mean age was 10.5 years. Eight patients presented with genu varum only and six cases presented with genu varum and internal tibial torsion (all cases were unilateral, seven right limbs and eight left limbs) with an age range between 10 and 16 years and a mean of was 12.4 years.
Results There is a statistically significant decrease of tibiofemoral angle (TFA) and mechanical axis deviation (MAD) after surgical correction of genu valgum among the included children with P value=0.001, and there is a statistically significant increase of lateral distal femoral angle (LDFA) after surgical correction of genu valgum with P value=0.001. There is a statistically significant increase of TFA, medial proximal tibial angle (MPTA), and MAD after surgical correction of genu varum among the included children with P value=0.001.
Conclusion Correction of multiplanar deformities around knee using monolateral external fixator has good results in genu valgus with the improvement of LDFA and TFA, and with the improvement of MPTA and TFA in genu varum and with correction of MAD in both of the deformity after surgical correction, with rotation correction using the ability of direction of Schanz placement.

Keywords: deformities, knee, monolateral external fixator


How to cite this article:
Fadel MH, Taha HA. Correction of multiplanar deformities around the knee with monolateral external fixator. Egypt Orthop J 2022;57:9-14

How to cite this URL:
Fadel MH, Taha HA. Correction of multiplanar deformities around the knee with monolateral external fixator. Egypt Orthop J [serial online] 2022 [cited 2022 Sep 25];57:9-14. Available from: http://www.eoj.eg.net/text.asp?2022/57/1/9/346385




  Introduction Top


Angular deformities around the knee are common during childhood and most cases are a variation in the normal growth pattern. Uncorrected deformities change the biomechanics by disturbing stress distribution on the knee joint weight-bearing surface [1],[2]. Pediatric lower extremity angular deformity arises in any of the three planes (coronal, sagittal, and transverse). These deformities can lead to gait abnormalities, pain, or the development of future arthritis and disability [3]. Correction of deformity around the knee depends on the position of center of rotation of angulation and the degree of deformity. Correction varies according to the age of the patient and the position of deformity. Osteotomy is still considered the “gold standard” by some, but it is associated with increased expenses and morbidities including overcorrection or undercorrection, neurovascular risk, hardware healing problems, and recurrent deformity with growth [2]. Osteotomy and internal fixation have many hazards including a longer operative time, more intraoperative bleeding, a higher risk of infection, delayed mobilization of the patient, and a long skin scar [4].

Monolateral external fixator with osteotomy has shown better results being simple, and offers accurate correction, a low complication rate, the ability to correct both valgus and varus deformities, and early mobilization of the patient [5].


  Patient and methods Top


A multicenter study case series prospective study was conducted from January 2020 to January 2021. A total of 30 patients with coronal plane deformities were included in the study.

Of them, 15 patients (all cases were unilateral, 9 left limbs and 6 right limbs) presented with genu valgum with female predominance at 53.3% and male 46.7%, with female to male ratio 1.14:1, with age range between 10 and 16 years, and mean age 10.5 years.

Eight patients presented with genu varum only and six cases presented with genu varum and internal tibial torsion (all cases were unilateral, seven right limbs and eight left limbs) with male predominance at 60.0% and female 40.0%, with male to female ratio 1.5:1, with age range between 10 and 16 years and mean 12.4 years ([Table 1]).
Table 1 Demographic data

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All cases meet inclusion criteria and were corrected with the monolateral external fixator (Hoffmann external fixator).

Inclusion criteria

  1. Genu valgus having a tibiofemoral angle (TFA) of more than 15 degrees.
  2. Genu varum having a metaphyseal-diaphyseal angle of more than 11 degrees.
  3. Presence of deformity causing functional disability of the patient.


Exclusion criteria

  1. Genu recurvatum.
  2. Flexion deformity.
  3. Pathological conditions (bone softening diseases).
  4. Severe deformities of more than 40 degrees when acute correction may lead to knee instability and nerve injury.


All children were assessed using plain x-rays (weight-bearing anteroposterior, lateral), computarized tomography (CT) scanogram, serum levels of parathyroid hormone, and calcium to exclude any parathyroid gland pathology that may contribute to the deformity.

Surgical technique

All cases were positioned supine, general anesthesia was given, and C-arm device was used.

Genu varum

Fibular osteotomy was done with a skin incision about 1 cm at the junction between the middle and distal one-third of the fibula followed by the monolateral frame.

Through two minimal skin incisions on the medial side of the proximal tibia under C-arm guide, the first Schanz proximal tibial epiphysis parallel to the joint line was placed. The second Schanz was of the same diameter and placed just below the physeal growth plate over the clamp. The third and fourth Schanz were placed in the tibial shaft from the medial side. In cases with internal tibial torsion, the direction of the third and fourth Schanz in the tibial shaft was from the medial side with posterior inclination to correct tibial torsion ([Figure 1]).
Figure 1 X-ray after corrective high tibial osteotomy.

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Tibial osteotomy with skin incision about 1 length is done 1 cm distal to tibial tuberosity and by the aid of C-arm drill bit, 4.5 mm incision is made for tibial osteotomy site, and then we introduced an osteotome to complete the osteotomy.

After osteotomy, translation was done to correct the mechanical axis followed by gradual correction followed by rod placement between proximal and distal clamps. Osteotomy site wound closure was performed by simple interrupted sutures ([Figure 2]).
Figure 2 Clinical photo of postcorrection and fixation of fixator in genu varum case.

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Genu valgus

Monolateral frame was placed with distal two Schanz. The first one was applied in the distal femoral epiphysis from lateral to the medial side and the second Schanz was applied parallel to the 1 s just proximal to the distal tibial growth plate through a clamp under C-arm guide.

Then the proximal two Schanz screws were placed through two minimal skin incisions about four-finger breadth proximal to the distal clamp into the femoral shaft through a single clamp.

Femoral osteotomy is done with the aid of a C-arm and using a 5-mm Schanz screw, and the osteotomy is carried out one-to-two finger breadth above and parallel to the physis through lateral, anterior, and with caution the posterior cortices, and then we introduced an osteotome to complete osteotomy ([Figure 3]).
Figure 3 X-ray after corrective supracondylar osteotomy.

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After osteotomy, translation was done to correct the mechanical axis followed by gradual correction to allow impaction of the distal segment into the proximal one followed by rod placement between proximal and distal clamps. Osteotomy site wound closure was performed by simple interrupted sutures ([Figure 4]).
Figure 4 Clinical photo of postcorrection and fixation of fixator in genu valgus case.

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Postoperative follow-up

  1. After x-rays [Anteroposterior (AP), lateral views] 2, 6, and 8 weeks.
  2. Before fixator removal, 3, 9, and 12 months (after fixator removal).



  Results Top


This was a prospective study that was performed on 30 children with angular knee deformities; 50% of the included patients had genu valgum and 50% of them had genu varum.

There is a statistically significant decrease of TFA and mechanical axis deviation (MAD) after surgical correction of genu valgum among the included children with P value=0.001, and there is a statistically significant increase of lateral distal femoral angle (LDFA) after surgical correction of genu valgum with P value=0.001. There is a statistically significant increase of TFA, medial proximal tibial angle (MPTA), and MAD after surgical correction of genu varum among the included children with P value=0.001 ([Table 2] and [Table 3]).
Table 2 The median and range values of TFA, LDFA, and MAD in patients with genu valgum

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Table 3 The median and range values of TFA, MPTA, and MAD in patients with genu varum

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The average time needed for full weight-bearing was 8 weeks and the average time needed for the complete radiological union was 7 weeks in genu varum cases. The average time needed for full weight-bearing was 9 weeks and the average time for the complete radiological union was 8 weeks for genu valgus cases.

Two patients had pin tract infection, both were suffering from genu valgum and were treated with oral antibiotics and followed up until improved; one patient with genu varum had lost correction of the deformity 2 weeks after surgery. This was discovered during the first follow-up visit, he was readmitted and the correction was done again.


  Discussion Top


Angular deformities of the knee alter the biomechanics of the knee by causing a distorted stress distribution on the weight-bearing surface of the knee joint. The deformities of the tibia or femur in the frontal plane led to MAD of the lower limb and malorientation of the joints above and below the level of deformity [6].

Mostafa et al. [7] is an Egyptian study that was conducted to evaluate the degree of corrections and complications done by osteotomy and hemiepiphysiodesis and found female predominance among genu valgum patients (67%), with a mean age of 8.4±3.1 years. There is a statistically significant decrease of TFA and MAD after surgical correction of genu valgum among the included children with P value=0.001, and there is a statistically significant increase of LDFA after surgical correction of genu valgum with P value=0.001.

Lim et al. [8] previously evaluated surgical correction of proximal tibia deformity in small children using monolateral external fixator and found a statistically significant increase of MPTA from 73° to 90° in varus tibia and from 104° to 89° in the valgus tibia, also MDA improved from 19° to 0° in varus tibia and from −25° to 2° in the valgus tibia.

In the present study, characteristics of patients with genu varum was studied, with male predominance at 60.0%, and male 40.0%, with male to female ratio 1.5:1, and age range between 7 and 12 years with median age 10 years.

There is a statistically significant increase of TFA, MPTA, and MAD after surgical correction of genu varum among the included children with a P value=0.001.

This goes in run with Pandya et al.’s [9] study that was performed on 17 consecutive patients with surgically corrected Blount disease using multiple axial corrections with a statistically significant decrease of MAD and TFA, and an increase of MPTA with P value=0.001.Another study by Özkul et al. [10] was conducted on 25 patients with genu varum with male predominance at 60%, which revealed a statistically significant decrease of MAD from 37.6 to 8.4 mm with P value <0.05, and statistically significant increase of MPTA from 76° to 89° with P value <0.05.

Ghasemi et al. [11] studied 43 patients with plates and 36 patients with external fixators with moderate uniplanar varus deformities and revealed statistically significant correction of MPTA from 83.9° to 90.9° with P value 0.001 and significant improvement of MAD from 23.6 mm medial to the midline to 6.9 mm lateral to midline with P value <0.001 that was similar to our study.

The limitation of the study is in the number of cases included, so more studies are needed.

Very few studies in using monoplaner fixator in acute correction of frontal plane and rotation deformities are available.


  Conclusion Top


Correction of multiplanar deformities around knee using monolateral external fixator has good results in genu valgus with the improvement of LDFA and TFA, and with the improvement of MPTA and TFA in genu varum, and with correction of MAD in both of the deformity after surgical correction, with rotation correction using the ability of direction of Schanz placement.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Aly AS, Abd Alkader MF, Thakeb MF. Low profile Ilizarov frame in correction of varus deformity in patients with adolescent Blount’s disease. Egypt J Hosp Med 2018; 71:2689–2696.  Back to cited text no. 1
    
2.
Carli A, Saran N, Kruijt J, Alam N, Hamdy R. Physiological referrals for paediatric musculoskeletal complaints: a costly problem that needs to be addressed. Paediatr Child Health 2012; 17:e93–e97.  Back to cited text no. 2
    
3.
Yilmaz G, Oto M, Thabet AM, Rogers KJ, Anticevic D, Thacker MM, Mackenzie WG. Correction of lower extremity angular deformities in skeletal dysplasia with hemiepiphysiodesis: a preliminary report. J Pediatr Orthop 2014; 34:336–345.  Back to cited text no. 3
    
4.
Takahashi T, Wada Y, Tanaka M, Iwagawa M, Ikeuchi M, Hirose D, Yamamoto H. Dome-shaped proximal tibial osteotomy using percutaneous drilling for osteoarthritis of the knee. Arch Orthop Trauma Surg 2000; 120:32–37.  Back to cited text no. 4
    
5.
Stevens PM, Kennedy JM, Hung M. Guided growth for ankle valgus. J Pediatr Orthop 2011; 31:878.  Back to cited text no. 5
    
6.
Cho TJ, Choi IH, Chung CY, Yoo WJ, Park MS, Lee DY. Hemiepiphyseal stapling for angular deformity correction around the knee joint in children with multiple epiphyseal dysplasia. J Pediatr Orthop 2009; 29:52–56.  Back to cited text no. 6
    
7.
Mostafa IA, Hassan MA, Shaaban El Mitwalli M. Management of genu valgum in children. Egypt Orthop J 2018; 54:27–35.  Back to cited text no. 7
    
8.
Lim C, Shin CH, Yoo WJ, Cho TJ. Acute correction of proximal tibial coronal plane deformity in small children using a small monolateral external fixator with or without cross-pinning. J Child Orthop 2021; 15:255.  Back to cited text no. 8
    
9.
Pandya NK, Clarke SE, McCarthy JJ, Horn BD, Hosalkar HS. Correction of Blount’s disease by a multi-axial external fixation system. J Child Orthop 2009; 3:291–299.  Back to cited text no. 9
    
10.
Özkul B, Camurcu Y, Sokucu S, Yavuz U, Akman YE, Demir B. Simultaneous bilateral correction of genu varum with Smart frame. J Orthop Surg (Hong Kong) 2017; 25:2309499017713915.  Back to cited text no. 10
    
11.
Ghasemi SA, Zhang DT, Fragomen A, Rozbruch SR. Proximal tibial osteotomy for genu varum: radiological evaluation of deformity correction with a plate vs external fixator. World J Orthop 2021; 12:140.  Back to cited text no. 11
    


    Figures

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

  [Table 1], [Table 2], [Table 3]



 

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