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Is portable ultrasonography accurate in the evaluation of Schanz pin placement during extremity fracture fixation in austere environments?

Brian P. Dahl, MD, FAWM, Aaron J. Pemberton, MD, Ryan T. Beck, MD, I. Bulent Cetindag, MD, Christopher D. Wohltmann, MD, Mark McAndrew, MD


Objective: The purpose of this study was to investigate the efficacy of ultrasonography to confirm Schanz pin placement in a cadaveric model, and the interobserver repeatability of the ultrasound methodology.
Design: This investigation is a repeated measures cadaveric study with multiple examiners.
Participants: Cadaveric preparation and observations were done by an orthopaedic traumatologist and resident, and two general surgery traumatologists.
Interventions: A total of 16 Schanz pins were equally placed in bilateral femora and tibiae. Four examiners took measurements of pin protrusion beyond the distal cortices using first ultrasonography and then by direct measurement after gross dissection.
Main Outcome Measure(s): Distal Schanz pin protrusion length measurements from both ultrasonography and direct measurement post dissection.
Results: Schanz pin protrusion measurements are underestimated by ultrasonography (p < 0.01) by an average of 10 percent over the range of 5 to 18 mm, and they display a proportional bias that increases the under reporting as the magnitude of pin protrusion increases. Ultrasound data demonstrate good linear correlation and closely represent actual protrusion values in the 5 to 12 mm range. Interobserver repeatability analysis demonstrated that all examiners were not statistically different in their measurements despite minimal familiarity with the ultrasound methodology (p > 0.8).
Conclusions: Despite the statistical imparity of pin protrusion measurement via ultrasound compared to that of gross dissection, a consideration of the clinical relevance of ultrasound measurement bias during an austere operating theatre leads to the conclusion that ultrasonography is an adequate methodology for Schanz pin protrusion measurement.


Schanz pin, protrusion, ultrasound, external fixation

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Lerner A, Soudry M: Armed Conflict Injuries to the Extremities: A Treatment Manual. Springer, 2011: 139-140.

Kazel M, Simpson RB, Tavassoli J, et al.: Ultrasound guidance for placement of external fixator pins: A cadaveric study. In Society of Military Orthopaedic Surgeons 44th Annual Meeting, San Diego, CA, December 2002.

Bland JM, Altman DG: Measuring agreement in method comparison studies. Stat Methods Med Res. 1999; 8(2): 135-160.

Gonçalves B, Ambrosio C, Serra S, et al.: US-guided interventional joint procedures in patients with rheumatic diseases—When and how we do it? Eur J Radiol. 2011; 79(3): 407-414.

De Zordo T, Mur E, Bellmann-Weiler R, et al.: US guided injections in arthritis. Eur J Radiol. 2009; 71(2): 197-203.

Ang SH, Lee SW, Lam KY: Ultrasound-guided reduction of distal radius fractures. Am J Emerg Med. 2010; 28(9): 1002-1008.

Mall NA, Kim HM, Keener JD, et al.: Symptomatic progression of asymptomatic rotator cuff tears: A prospective study of clinical and sonographic variables. J Bone Joint Surg Am. 2010; 92(16): 2623-2633.

Tashjian RZ, Hollins AM, Kim HM, et al.: Factors affecting healing rates after arthroscopic double-row rotator cuff repair. Am J Sports Med. 2010; 38(12): 2435-2442.

Ottenheijm RP, Jansen MJ, Staal JB, et al.: Accuracy of diagnostic ultrasound in patients with suspected subacromial disorders: A systematic review and meta-analysis. Arch Phys Med Rehabil. 2010; 91(10): 1616-1625.

Iannotti JP, Ciccone J, Buss DD, et al.: Accuracy of office-based ultrasonography of the shoulder for the diagnosis of rotator cuff tears. J Bone Joint Surg Am. 2005; 87(6): 1305-1311.

Teefey SA, Rubin DA, Middleton WD, et al.: Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases. J Bone Joint Surg Am. 2004; 86-A(4): 708-716.

Mahaisavariya B, Laupattarakasem W: Ultrasound or image intensifier for closed femoral nailing. J Bone Joint Surg Br. 1993; 75(1): 66-68.

Mahaisavariya B, Songcharoen P, Chotigavanich C: Soft tissue interposition of femoral fractures: Detection by ultrasonography during closed nailing. J Bone Joint Surg Br. 1995; 77(5): 788-790.



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