Clin Orthop Surg.  2010 Jun;2(2):85-89. 10.4055/cios.2010.2.2.85.

Change in Effective Leg Length after Angular Deformity Correction by Hemiepiphyseal Stapling

• Jung HJ
• Cho TJ
• Choi IH
• Chung CY
• Yoo WJ
• Park MS
• Bae JY

• KMID: 1719334
• DOI: http://doi.org/10.4055/cios.2010.2.2.85

Abstract

BACKGROUND
The hemiepiphyseal stapling has both positive and negative effects on effective leg length. The purpose of this study was to analyze change in effective leg length after angular correction by hemiepiphyseal stapling, and to validate in clinical cases.
METHODS
Mathematical analysis of a hemiepiphyseal stapling model was conducted. The induced formula was validated in 6 cases fulfilling the assumptions of the model. Anatomical parameters involved in this formula were measured in additional 21 cases undergoing hemiepiphyseal stapling or hemiepiphysiodesis.
RESULTS
Effective leg length increased or decreased according to three parameters in this model: 1) limb length distal to the operated physis (L), 2) width of the operated physis (d), and 3) the amount of angular deformity to be corrected (theta). Actual change in effective leg length of 6 cases similar to this model coincided with the predicted change at least in its direction. L/d ratio was 4.82 +/- 0.51.
CONCLUSIONS
Considering the narrow range of the L/d ratio, hemiepiphyseal stapling is likely to decrease effective leg length if the amount of angular correction is less than 10degrees, whereas to increase it if the amount of angular correction is larger than 16degrees. This should be taken into consideration when selecting the surgical method for angular deformity correction in skeletally immature patients.

Keyword

Angular deformity correction; Hemiepiphyseal stapling; Effective leg length

MeSH Terms

Adolescent
Child
Epiphyses/growth & development/*surgery
Female
Genu Valgum/*surgery
Genu Varum/*surgery
Humans
Leg Length Inequality/diagnosis/*etiology
Male
*Surgical Stapling/adverse effects

Figure

• 

  Fig. 1 Schematic diagram of the mathematical analysis. (A) The amount of angular correction and the length of the operated limb was designated as θ and L, respectively. Gain of effective leg length, when angular correction has been achieved, will be L · (1 - cos θ). "A" is the effective leg length. (B) The width of the operated physis was designated as d · When angular correction is achieved by hemiepiphyseal stapling, the contralateral limb will grow at this physis by d · tan θ; linear growth of the operated limb will be a half of this.

• 

  Fig. 2 Equation 2 is plotted on plane of L/d ratio and the amount of angular correction (θ). Dots depict six cases in Tables 1 and 2. If a dot is above and right to the curve, gain of effective leg length is expected. Vertical arrows indicate range of the evalue corresponding to the range of L/d ratio with 2 standard deviations. A thick transverse line denotes the mean value, thin lines range of 1 standard deviation, and dotted line that of 2 standard deviations.

• 

  Fig. 3 Teleradiographs, preoperative (A) and post-correction (B) of case 3 in Tables 1 and 2. Note the improvement in preoperative pelvic obliquity after angular correction using hemiepiphyseal stapling of the distal femur.

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