Objective quantitative methods to evaluate microtia reconstruction: A scoping review

Abstract

Background: Commonly used methods to evaluate auricles are subjective and are therefore not specific, comprehensive, and precise nor effective in the assessment of microtia reconstruction outcomes. This scoping review aimed to summarize the objective methods for the accurate evaluation of microtia reconstruction.

Methods: We performed a scoping review of publications that used objective measurement methods to evaluate outcomes of microtia reconstruction according to the PRISMA-ScR guidelines. A systematic literature search was conducted in the Embase, PubMed, Cochrane, CNKI, and VIP databases, and literature references were screened for additional records. Studies that evaluated auricles after microtia reconstruction using quantitative anthropometric methods were included, and data on these methods were collected.

Results: Twenty-five publications reported on quantitative objective outcome measurements. Thirteen studies evaluated auricular protrusion, three articles assessed the position or symmetry, and twelve studies reported on auricle size. The quantitative measurements of fine structures, such as the tragus and concha, were described in three studies. All described measurements used manual landmarking, where fifteen studies described well-defined landmarks, fifteen studies described poorly defined landmarks, and four studies used a combination of well and poorly defined landmarks.

Conclusion: The objective evaluation of microtia reconstruction outcomes is hindered by significant heterogeneity of measurement methods. The measurement methods used for general auricular measurements (auricular protrusion, auriculocephalic angle, and size) used in microtia reconstruction were abundant, while measurements of auricular position and the fine structures of the auricle were limited. Three-dimensional imaging combined with computer analyses poses promising future alternatives.

Keywords: Microtia; Objective evaluation; Systematic review.

Figure 1

Overview of the entire study selection process.

Figure 2

Graphs showing the landmarks used for measuring auricular protrusion. A Solid lines indicate nonauricular landmarks used for specifying auricular landmarks (note: not every research specified if a reference plane was used). Dotted lines indicate the corresponding landmarks from the posterior view. Arrows lines: distance from landmarks to mastoid (Protrusion) or position to place the protractors (Angle). B Ex: Excocanthion; pT: Paratragion. Red line: Distance measured before elevation. Green line: distance measured after elevation (projected distance behind the ear). The auriculocephalic angle is calculated with inverse trigonometric functions of the preoperative and postoperative distance connecting these two landmarks. C Protrusion measured as distance between outer and medial edge of ear (divided by horizontal line between the pupils). D Horizontal full lines passing landmarks and intersect with helix. Dotted lines indicating the corresponding landmarks from lateral view and posterior view. Double arrows lines: distance from landmarks to mastoid (Protrusion). Colored regions: possible region chosen for measurements.

Figure 3

A Graph showing the methods used for measuring auricular size.

Figure 4

Graphs showing the methods used for measuring auricular position/symmetry. A Ideally, the anterior coronal plane passing the three margins helps define the anterior-posterior position of bilateral ears. However, in most of the cases what actually passes the three margins is an oblique plane. Axial plane passing subaurale helps defining superior-inferior ear position. The distance of bilateral oblique planes was measured to define anterior-posterior difference. The distance of bilateral horizontal planes was measured to define superior-inferior difference. In the picture one side of lateral view of planes passing their landmarks was shown. B Green line: Bilateral ear position was compared by distance between nasal tip and tragus. Clear film rhomboid (Left) is traced from the normal side and then flipped over onto the reconstructed side (Right). Length (Red) and axial angle (Yellow) of bilateral ears are compared.