Breast Implants Under or Over the Muscle: What London Patients Should Know

TL;DR. There is no universally better position for breast implants: placing them under the muscle usually gives more soft tissue cover over the upper part of the implant, placing them over the muscle avoids the implant moving when your chest muscle contracts, and the right choice depends on your anatomy, your lifestyle and which trade-offs you are prepared to accept.

When people start researching breast augmentation, implant size tends to dominate the conversation. Yet the position of the implant, in front of or behind the pectoralis major muscle, can matter just as much to how the breast looks, feels and moves over the years. It also affects recovery, the problems that can develop later and how future breast screening is carried out. At our clinic in Kensington, it is one of the most common topics we discuss in consultation, and online forums often give confident answers that do not apply to the person reading them. If you are considering breast augmentation in London, this guide sets out the options honestly, including the downsides, so that you can arrive at a consultation with better questions rather than a fixed idea.

The main implant positions, explained plainly

Every breast implant sits in a 'pocket' that the surgeon creates during the operation. There are broadly three options, although the terms used online are not always consistent.

Subglandular (over the muscle). The implant sits behind the breast tissue and in front of the pectoralis major, the large fan-shaped muscle across the upper chest. The only cover over the implant is your own breast tissue, fat and skin.

Subfascial. This is a variation of the over-the-muscle approach. The muscle is covered by a thin sheet of connective tissue called fascia, and the implant is placed beneath that layer but still in front of the muscle. The fascia is very thin, so the extra cover it adds is modest, and the evidence comparing it with standard subglandular placement is limited.

Dual plane (partially under the muscle). When people talk about implants going 'under the muscle' in cosmetic surgery, they almost always mean dual plane. The pectoralis major does not cover the whole breast; it covers the upper and inner portion. In a dual plane augmentation, the lower attachments of the muscle are released so that the upper part of the implant sits behind the muscle while the lower part sits behind the breast tissue alone. The surgeon can adjust how much the breast tissue is separated from the muscle, which allows some tailoring to the shape of the breast.

Fully submuscular placement, where the implant is completely covered by muscle, is used much less often in cosmetic augmentation today and is more commonly associated with certain types of reconstructive surgery.

None of these positions is automatically superior. Each shifts the balance between cover, movement, shape and recovery in a different way, which is why the conversation needs to start with your body rather than with a preference you have read about.

Why your own tissue matters more than any trend

The single biggest factor in choosing a pocket is how much natural tissue you have to cover the implant, particularly in the upper part of the breast. An implant is a manufactured device with edges and folds. If there is plenty of breast tissue and fat over it, those features are softened and largely hidden. If there is very little, they can show through as a visible edge or as rippling, a wave-like pattern in the skin that is often most noticeable when leaning forward or in certain lights.

During examination, your surgeon will usually assess the thickness of the tissue in the upper breast with a simple pinch test. Many surgeons use a pinch thickness of around two centimetres as a rough working guide: below that, extra cover from the muscle is often recommended, and above it, an over-the-muscle position becomes a more realistic option. This is a guide rather than a rule, and it is only one part of the picture.

Other things we consider include:

• The amount of droop (ptosis). Breasts that sit lower on the chest, often after pregnancy, breastfeeding or weight loss, behave differently with each pocket. This can change the whole plan, as explained later.
• Skin quality and elasticity. Thin or stretched skin offers less support over time and makes implant edges more likely to show.
• Chest wall shape and asymmetry. Most people have some difference between the two sides, and a curved or uneven rib cage can affect how an implant sits.
• The implant itself. A larger implant relative to the width of your chest stretches the tissue more and makes adequate cover more important. Our separate guide to choosing implant size, shape and profile explains why the base width of your breast usually guides sensible sizing.
• Your build and activity. A slim, very active person with strong pectoral muscles has different considerations from someone with fuller natural breasts who does little upper body training.

This is why two patients asking the same question in London can receive different, equally reasonable advice. A pocket that suits someone with generous natural tissue may lead to visible edges in a very slim patient, and the reverse is also true.

Under the muscle: what it can offer, and what it costs you

The main reason surgeons recommend dual plane placement is cover. The muscle adds a layer over the upper part of the implant, which is exactly where slim patients are most likely to see an edge. For many, this helps create a gentler slope from the chest into the breast and reduces the chance of visible rippling in the upper breast. Rippling can still occur in the lower and outer breast, where the muscle does not reach, so it is reduced rather than eliminated.

A number of published studies have also suggested that capsular contracture, where the scar tissue around an implant tightens and hardens, may be less common with submuscular placement than with subglandular placement. The evidence is not entirely consistent, and many other factors influence this risk, so it should be seen as a possible benefit rather than a promise. Some radiologists also find it slightly easier to image breast tissue when the implant sits behind the muscle.

The trade-offs are real, and they are not always explained well:

• Animation deformity. Because the muscle lies over part of the implant, contracting the pectoralis major can squeeze or move it. Some patients notice the breast shifting upwards or outwards, or a dimple appearing, when they press their hands together, lift something heavy or do push-ups. For many it is mild; for others, particularly people who train their chest regularly, it can be bothersome. It is a known consequence of the technique, not a sign of poor surgery.
• More discomfort early on. Releasing and stretching the muscle generally makes the first days and weeks more uncomfortable than an over-the-muscle operation, with a tight, heavy feeling across the chest.
• A settling period. Implants under the muscle often sit high and feel firm at first, gradually settling and softening over weeks to months as the muscle relaxes. This can be unsettling if you are not expecting it.
• Movement over time. In some patients, the pressure of the muscle may push implants slightly outwards or upwards over the years.
• Less help with droop. If the breast tissue is sagging, an implant held up by the muscle can sit higher than the breast, which then slides down over it. Dual plane adjustments reduce this risk but cannot always overcome it.

Over the muscle: what it can offer, and what it costs you

Placing the implant over the muscle leaves the pectoralis major untouched, which brings several practical advantages. There is no animation deformity, because contracting the muscle does not affect the implant. Early recovery is often more comfortable, because no muscle is released. The implant sits directly behind the breast tissue, so it fills the lower breast well, and in patients with mild laxity it may give the breast a little more projection than a dual plane approach.

For people who do a lot of weight training, gymnastics, climbing or other chest-intensive sport, and who also have enough natural tissue to cover an implant, this position can be a sensible choice. It can also suit patients who already have reasonably full breasts and want a modest change in volume.

The downsides mirror the advantages of the dual plane approach:

• Visible edges and rippling. In slim patients with little breast tissue, the outline of the implant, particularly its upper edge, can be seen or felt. This can create an abrupt step between the chest and the breast, and it tends to become more noticeable as tissue thins with age or weight loss.
• Possibly higher contracture risk. As mentioned above, some studies suggest capsular contracture may be more common in this position, although the evidence is mixed.
• Tissue stretch over time. All implants add weight that the skin and breast tissue must support. Without the muscle sharing some of that load, the lower breast may stretch more over the years, particularly with larger implants.
• Screening considerations. An implant directly behind the breast tissue can obscure more of that tissue on a mammogram.

The subfascial pocket is sometimes offered as a middle ground. It may be reasonable for some patients, but it is not a substitute for genuine tissue cover in a very slim patient.

Risks that come with implants wherever they sit

Choosing a pocket changes the balance of some risks, but it does not remove the risks of having implants. These apply whichever position you choose.

• Implants are not lifetime devices. Most people with implants will need further surgery at some point, whether to replace or remove them, to treat a complication, or because the breasts change with age, pregnancy or weight. It is wise to plan for this practically and financially.
• Capsular contracture. Your body forms a capsule of scar tissue around every implant. In some people it tightens, causing firmness, distortion and sometimes pain, and further surgery may be needed.
• Rupture. Modern silicone implants use a cohesive gel, but the shell can still fail. A rupture may cause no symptoms, which is why imaging may be advised if there are concerns.
• Surgical complications. These include bleeding and haematoma, infection, seroma (fluid collection), poor scarring, changes in nipple or breast sensation, asymmetry and the general risks of anaesthesia, including blood clots.
• BIA-ALCL. Breast implant associated anaplastic large cell lymphoma is a rare cancer of the immune system that can develop in the fluid or capsule around an implant. It has been linked predominantly with textured implants. The MHRA monitors this and publishes guidance, and you should ask what implant surface is being proposed and why.
• Systemic symptoms. Some people with implants report symptoms such as fatigue, joint pain or difficulty concentrating, sometimes described as breast implant illness. It is not fully understood and is not a recognised diagnosis, but it is reported, and it deserves an open discussion rather than dismissal.

In England, patients can choose to have their implant details recorded on the Breast and Cosmetic Implant Registry, which helps trace people if a safety issue with a particular device emerges in future. We recommend asking about this and keeping your own record of the implant manufacturer, type and size.

Exercise, pregnancy and breast screening

Because the right pocket can depend on how you live, it helps to think ahead about the next ten or twenty years, not just the next few months.

Exercise. If you regularly do chest-intensive training such as bench press, push-ups, pole fitness or climbing, raise this early in consultation. With dual plane implants, animation deformity is more likely to be noticeable in this group. Whatever the pocket, you will need to avoid strenuous upper body exercise for a period after surgery and build back gradually. Our week-by-week guide to breast augmentation recovery covers what this typically involves.

Pregnancy and breastfeeding. Pregnancy changes the breasts, and those changes can alter how implants look afterwards, sometimes causing droop that needs further surgery. Many people with implants are able to breastfeed, but no one can promise this, with or without implants, and the choice of incision can matter more than the pocket. Incisions around the areola carry a greater chance of affecting milk ducts and nipple sensation than those in the fold beneath the breast. If you are planning a family in the near future, it is often sensible to wait.

Breast screening. Implants do not prevent you from having mammograms, and the NHS Breast Screening Programme invites women from around the age of 50. Tell the radiographer about your implants. They may use additional displacement views, where the implant is gently moved aside so that more breast tissue can be imaged. Implants can still hide some tissue, and this tends to be more of an issue when they sit over the muscle. Being breast aware and reporting any new lump, swelling or change in shape remains important at every age.

Who should think twice, and when placement is not the real question

Sometimes the most useful thing a consultation can do is reframe the question. If your breasts have dropped significantly, with the nipple sitting at or below the fold beneath the breast, an implant alone in either pocket is unlikely to achieve a lifted appearance. An implant under the muscle can sit high while the breast tissue hangs below it, sometimes called a waterfall deformity, and an implant over the muscle may simply add weight to tissue that is already stretched. A breast lift, with or without an implant, may be the more honest recommendation, and it involves more scarring.

For patients whose concerns after pregnancy go beyond the breasts, a combined plan such as a mummy makeover may be discussed, although combining procedures increases operating time and recovery and is not right for everyone. Patients who want only a modest increase in volume and have fat available elsewhere may ask about fat transfer, which has its own limitations, including unpredictable survival of the transferred fat and the possible need for more than one session.

Breast augmentation may not be suitable, or may be better postponed, if you:

• are under 18, or your breasts are still developing;
• smoke or use nicotine and cannot stop well before and after surgery, as this raises the risk of wound problems;
• expect significant weight change or are planning a pregnancy soon;
• have medical conditions that increase surgical or anaesthetic risk and are not well controlled;
• feel pressured by a partner, friends or social media rather than wanting surgery for yourself;
• have persistent distress about your appearance that has not eased with previous procedures.

We screen thoughtfully for body dysmorphic disorder and will tell you if we do not think surgery is in your interests. That conversation is part of responsible practice, not a barrier.

Booking your consultation

Consultations at our Kensington clinic are doctor-led and unhurried. We will take a full medical history, examine and measure your chest and breasts, assess tissue thickness, droop and asymmetry, and talk through what you are hoping for and what you would rather avoid. We will explain which implant positions are realistic for your anatomy, the reasoning behind any recommendation, and the risks and limitations that apply to you specifically. You are welcome to bring a list of questions or someone you trust.

Operations are performed by Dr Hassan Soueid or one of our qualified surgeons, and you can read more about Dr Hassan Soueid, our Founder and Medical Director, before you visit. We build in time for reflection between consultation and any decision to proceed, in line with GMC guidance on cosmetic interventions, and you will never be asked to commit on the day. We are also introducing HonestFace, our own iPad app for digital consultation forms, consent signing and secure patient records, so that your paperwork is clear and easy to review.

The clinic is registered with the Care Quality Commission. If you would like to talk through implant placement with a doctor in London, you can book a consultation with our team in Kensington.