Should breast implants go under or over the muscle?
⚠️ When to contact your surgeon after breast augmentation
If you notice increasing firmness, pain, or visible distortion of a breast implant at any point after surgery, contact your surgeon promptly. These can be signs of capsular contracture or another complication. If you develop sudden swelling, redness, warmth, or fever, seek medical attention right away, as these may indicate infection or, rarely, a fluid collection that needs urgent treatment.
Short answer
Research consistently shows that placing implants under the muscle (submuscular) significantly lowers the risk of capsular contracture, which is scar tissue hardening around the implant. However, submuscular placement does cause some muscle changes over time, and newer techniques like dual-plane or subfascial placement offer additional options worth discussing with your surgeon.
What the research shows
The strongest evidence focuses on capsular contracture, a complication where scar tissue around the implant tightens and can cause pain or distortion. A large meta-analysis pooling data from over 17,500 implants found that implants placed over the muscle (subglandular) carried more than twice the risk of capsular contracture compared to under-the-muscle (submuscular) placement. [1] An older but notable cohort study found contracture rates of 58% with subglandular versus only 9.4% with submuscular placement. [3] A review of complications confirmed these findings, noting that submuscular placement is a key factor in reducing capsular contracture risk. [6] Registry data from Austria also shows that surgeons have been gradually moving away from subglandular placement over time. [5]
Trade-offs with under-the-muscle placement
Going under the muscle is not without its own considerations. A randomized controlled trial using MRI scans found that 12 months after submuscular augmentation, patients showed an average 49.8% reduction in pectoralis major muscle volume, meaning some muscle atrophy occurred. By contrast, subglandular patients showed about 22.8% reduction in breast gland volume but no muscle atrophy. [2] Neither outcome caused obvious cosmetic problems in most patients in that study, but it is worth knowing that both placements affect nearby tissue over time.
Other placement options
Beyond over or under the muscle, surgeons also use a subfascial approach, which places the implant beneath a thin tissue layer covering the muscle without disturbing the muscle itself. Early cohort data suggest this can reduce implant edge visibility compared to subglandular placement while avoiding muscle disruption. [7] A newer variation called dual plane subfascial combines techniques and may be particularly useful for thin patients or those converting from a previous subglandular placement. [4] These newer approaches need more long-term data before strong conclusions can be drawn.
What to ask your surgeon
The right placement for you depends on your body shape, the amount of natural breast tissue you have, your lifestyle (for example, athletes who heavily use chest muscles may notice animation deformity with submuscular implants), and the implant type chosen. Ask your surgeon: Which placement do you recommend for my body, and why? What are the contracture rates in your own practice? Are there reasons I might not be a good candidate for submuscular placement? Being well-informed helps you make the decision that fits your goals and anatomy best.