A Quantitative Analysis of Animation Deformity in Prosthetic Breast Reconstruction

Abstract

Background: Animation deformity is characterized by implant deformity with pectoralis contraction after subpectoral implant-based breast reconstruction. Extant methods to measure and analyze animation deformity are hampered by the paucity of objective, quantitative data. The authors endeavored to supplement subjective measures with an in-depth quantitative analysis. Methods: Patients undergoing subpectoral implant-based breast reconstruction were followed prospectively with video analysis of animation deformity. Nipple displacement and surface area of contour deformity in resting and contracted states were quantified using imaging software. Degree of animation was compared to breast size, body mass index, division of pectoralis muscle, complications, and radiation therapy. Results: One hundred forty-five reconstructed breasts (88 patients) were analyzed. Mean nipple displacement was 2.12 ± 1.04 cm, mean vector of nipple displacement was 62.5 ± 20.6 degrees, and mean area of skin contour irregularity was 16.4 ± 15.41 percent. Intraoperative pectoralis division, smooth/round implants, and bilateral reconstructions were associated with greater deformity. A three-tiered grading system based on thresholds of 2-cm net nipple displacement and 25 percent skin contour irregularity placed 41.4 percent of breasts in grade 1, 35.9 percent in grade 2, and 22.8 percent in grade 3. Interrater variability testing demonstrated 89.5 percent overall agreement (kappa = 0.84). Conclusions: This study presents the first quantitative analysis of animation deformity in prosthetic breast reconstruction. Geometric analysis of nipple displacement vector and increasing animation with pectoralis division both implicate the inferior pectoralis myotome as a primary driver of animation deformity. A concomitant grading schema was developed to provide a standardized framework for discussing animation from patient to patient and from study to study.

An overview of animation deformity in prosthetic breast reconstruction

“…Likewise, Spear has personally advocated for maintaining the inferior pectoralis insertion onto the sternum to prevent animation deformity (personal communication, S. Spear, 2016). These observations are in congruence with findings form our own patient population that the average vector of nipple displacement is 62 degrees in the superolateral directiona line approximately parallel to the action of the inferior pectoralis fibers (accepted for publication, Figure 2) (8).…”

“…So far, the only factor that clearly contributes to developing animation deformity is placing the implant in a sub-pectoral position. Patient factors, including age, body mass index (BMI), handedness and athleticism have not been shown to correlate with development or severity of animation deformity (2,8). Surgical factors, such as implant size, implant type and mastectomy specimen weight, as well as peri-operative factors, such as radiation, infection and seroma, have also not been shown to correlate with development or degree of animation deformity (2,8).…”

“…Patient factors, including age, body mass index (BMI), handedness and athleticism have not been shown to correlate with development or severity of animation deformity (2,8). Surgical factors, such as implant size, implant type and mastectomy specimen weight, as well as peri-operative factors, such as radiation, infection and seroma, have also not been shown to correlate with development or degree of animation deformity (2,8). In our patient series, we have found division of the pectoralis with placement of acellular dermal matrix (ADM) is the only factor that correlates with increasing severity of animation deformity.…”

“…To do this, we measured amount of nipple displacement (in cm) with pectoralis muscle contraction, as well as percent surface area of skin contour irregularity on the breast mound. A total of 145 breasts (88 patients) were analyzed by still images captured on video at rest and with pectoralis contraction (Figure 3) (8). In this group, average nipple displacement was 2.12 cm (SD 1.04 cm), average vector of nipple displacement was 62.5 degrees (SD 20.6 degrees) in the superolateral direction and average percent surface area of skin contour irregularity was 16.4% (SD 15.41%).…”

“…They Both of the above-mentioned scales are relatively new, presented in the literature within the past 2 years. Given they both rely on subjective assessment of the amount of distortion by the rater, we developed a quantitative grading scale based on the measurements presented in the previous section to help standardize description of animation deformity across patients and raters (8). Our scale divides patients into three categories based on amount of nipple displacement (in cm) and percent surface area of skin rippling evident on the breast mound.…”