The appearance of a breast implant looking “square” or “boxy” is an aesthetic concern that frequently leads individuals to seek professional consultation. This unnatural contour change is usually caused by a reaction within the surrounding tissues or the interaction between the implant and the chest anatomy, not a defect in the implant material. The boxy look manifests in two ways: a temporary distortion during movement, or a permanent change present even at rest. Understanding the specific cause is the first step toward restoring a smooth, natural breast contour.
Understanding Pectoral Muscle Animation
The dynamic form of breast distortion is known as Animation Deformity, a consequence of submuscular implant placement. This method positions the implant partially or entirely beneath the pectoralis major muscle. This technique is often selected because the muscle provides a protective layer, helping to obscure the implant edges and potentially lower complication risks.
The pectoralis major is a large, fan-shaped muscle that contracts during activities like pushing or lifting, or when the arm is moved across the body. When this muscle tightens, it squeezes the implant pocket, pushing the implant downward or laterally. This temporary compression creates the visible distortion, making the upper pole of the breast appear boxy, rippled, or unnaturally shifted.
The severity of the animation relates directly to the degree of muscle involvement; a greater portion of the implant covered by the muscle results in a more noticeable change. While not a health concern, this distortion is a significant aesthetic issue for many patients, particularly those who are physically active or have low body fat. The appearance resolves instantly once the muscle relaxes, distinguishing it from a static deformity.
The Role of Scar Tissue Tightening
A static, permanent square appearance is commonly caused by Capsular Contracture, a pathological response to the foreign implant material. The body naturally forms a scar tissue capsule around any implant, but contracture occurs when this capsule thickens and tightens excessively. The resulting pressure forces a change in the implant’s natural shape.
The contracting capsule acts like a tight, internal vise, squeezing a normally round or teardrop-shaped implant into a hard, unnatural sphere or boxy configuration. This change is not dynamic; the distortion and firmness are present at all times. This condition is classified using the Baker Grading Scale, ranging from Grade I (soft, normal appearance) to Grade IV (hard, painful, and severely distorted).
A Grade III or Grade IV contracture is typically required before the implant is visibly misshapen. The primary theory behind this tightening involves a low-grade, subclinical infection or chronic inflammation, often associated with a bacterial biofilm on the implant surface. This chronic irritation stimulates the scar tissue cells to contract with abnormal force, leading to the visual change and palpable firmness.
Corrective Measures and Revision Options
Addressing the square appearance requires a precise diagnosis by a board-certified plastic surgeon to determine if the cause is dynamic muscle animation or static capsular contracture. The surgical approach for Animation Deformity often involves converting the implant pocket from submuscular to the prepectoral plane, positioned over the muscle. This revision surgery eliminates the interaction between the pectoral muscle and the implant, immediately resolving the distortion.
A surgeon may also choose to perform a targeted muscle release (myotomy) on the lower fibers of the pectoralis muscle to prevent them from grabbing the implant. In many cases, prepectoral conversion is performed in conjunction with an acellular dermal matrix (ADM), which acts as an internal scaffold. The ADM provides a new, supportive layer of tissue over the implant, helping to maintain breast shape and reduce rippling.
For Capsular Contracture, the standard treatment is a capsulectomy, involving the surgical removal of the constricting scar tissue capsule. A total capsulectomy removes the entire capsule, which is the most definitive way to eliminate the source of pressure and distortion. This procedure is almost always performed along with exchanging the existing breast implant for a new one.
To minimize the risk of recurrence, the surgeon may recommend switching to a different implant type, such as one with a textured surface, or changing the implant location to the subglandular plane. Fat grafting, which involves injecting the patient’s own purified fat tissue, can also be utilized to thicken the soft tissue envelope around the implant. The choice between these revision options is individualized, depending on the severity of the distortion, the patient’s anatomy, and the desire to prevent the boxy appearance from returning.