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Year : 2012  |  Volume : 46  |  Issue : 1  |  Page : 115
Authors' reply

Department of Orthopaedics, Christian Medical College, Vellore, Tamil Nadu, India

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Date of Web Publication10-Jan-2012

How to cite this article:
Madhuri V, Dutt V, Samuel K, Gahukamble AD. Authors' reply. Indian J Orthop 2012;46:115

How to cite this URL:
Madhuri V, Dutt V, Samuel K, Gahukamble AD. Authors' reply. Indian J Orthop [serial online] 2012 [cited 2020 Jan 23];46:115. Available from:

We thank Sebestyen Andor, Boncz Imre and Toth Ferenc [1] for their interest in our article. [2] Ficat and Arlet in their landmark research on avascular necrosis have demonstrated the effect of intraosseous head pressures in the etiology of femoral head avascular necrosis (AVN); [3] however, the role of the absolute pressures in the vascularity of the femoral head is not under consideration in our article.

Our technique is not a diagnostic technique for AVN, but a tool to assess intraoperative arterial blood flow to the femoral head to guide the surgeon. The decreased vascularity is at times because of the positioning of the dislocated head or capital femoral epiphysis due to stretch on the vessels, and will disappear once this is rectified.

The transducer in our system is not at the tip of catheter, and hence the pressures measured cannot be compared with intraosseous pressure data collected by some of the other techniques because of variables such as damping. Damping results from friction of the fluid moving within the tubing. When an arterial trace is sinusoidal and loses fine detail, it's called a 'damped' trace. Air bubbles, blood clots and excessively tortuous arterial line circuits are known to cause a damped trace. [4] Paynel et al. have used short tubing to minimize sub optimal damping of the arterial trace. [5] Soft tubings' on the other hand produce an under-damped spiked arterial trace. [6] The pressure in this system is also affected by the patient's blood pressure during anaesthesia which may be at variance from their normal.

Thus, the pressure that is measured by the system correlates with the intraosseous pressure; however, it is not the absolute pressure. What we imply by the sentence under contention is that the presence of an 'intraosseous pressure reading' in the absence of an arterial wave form should be interpreted with caution, as the pressure readings alone do not indicate the presence of an arterial blood flow. In the context of assessing head vascularity by our technique at present, the absolute pressure as recorded by the system does not contribute adequately to the surgical decision making in the absence of a wave form. To identify a safe range of pressure in the group, we require establishment of normal ranges of pressure in a standardised, accurate and reliable system which rightly would involve ethical issues.

   References Top

1.Sebestyén A, Boncz I, Tóth F. Intra-operative femoral head vascularity assessment: An innovative and simple technique (Letter 2). Indian J Orthop 2012;46:114-5.  Back to cited text no. 1
2. Madhuri V, Dutt V, Samuel K, Gahukamble AD. Intra-operative femoral head vascularity assessment: An innovative and simple technique. Indian J Orthop 2011;45:231-5.  Back to cited text no. 2
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3.Ficat RP, Arlet J. Functional investigation of bone under normal conditions. In: Hungerford DS (editor). Ischaemia and necrosis of the bone, 1 st ed. Baltimore: Williams and Wilkins; 1980. p. 29-52.  Back to cited text no. 3
4.Ercole A. Attenuation in invasive blood pressure measurement systems. Br J Anaesth 2006;96:560-62.  Back to cited text no. 4
5.Paynel RA, Isnardi D, Andrews PJ, Maxwell SR, Webb J. Similarity between the suprasystolic wideband external pulse wave and the first derivative of the intra-arterial pulse wave. Br J Anaesth 2007;99:653-61.  Back to cited text no. 5
6.Dyer I, Williams DJ. Common errors in clinical measurement. Anaesthesia and intensive care medicine 2005;12:405-7.  Back to cited text no. 6

Correspondence Address:
Vrisha Madhuri
Department of Orthopaedics, Christian Medical College Hospital, Ida Scudder Road, Vellore 632 004, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

PMID: 22345822

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