A transtibial amputation is the surgical removal of the leg below the knee, including the foot, ankle joint, and the lower portions of the two leg bones (the tibia and fibula). It’s one of the most common major limb amputations performed, and because it preserves the knee joint, it generally allows for better mobility and prosthetic use than amputations at higher levels. The cut is typically made about 10 to 15 centimeters below the bony bump you can feel just under your kneecap.
Why This Surgery Is Performed
Poor blood flow is the overwhelming reason. Peripheral vascular disease, often combined with diabetes, accounts for roughly 85% of all lower limb amputations. When blood supply to the lower leg becomes so compromised that tissue dies or chronic wounds won’t heal, amputation may be the only option to stop the spread of infection and preserve the rest of the limb.
The remaining cases involve trauma (severe crush injuries, blast injuries in military settings), cancer in the bone or soft tissue, deep infections that don’t respond to antibiotics, and occasionally congenital limb differences. Surgeons generally try to save as much of the leg as possible, so a below-knee amputation is preferred over an above-knee one whenever there’s enough healthy tissue and blood supply to support healing at that level.
What Happens During Surgery
The surgeon marks out skin flaps, typically creating a longer flap from the back of the calf to fold over and cushion the end of the bone. This is called the posterior flap technique, sometimes referred to as the Burgess method, and it’s the most widely used approach. The tibia and fibula are cut with a saw, and the sharp edges are smoothed down so they won’t press painfully against the skin. Muscles are then secured over the bone ends to provide padding, and the skin flaps are closed with sutures.
A newer variation, the Ertl technique, creates a bony bridge between the tibia and fibula to form a more stable, weight-bearing end. This approach is sometimes used for younger, active patients, particularly in military trauma settings. However, it carries additional risks: about 32% of patients in one study experienced complications related to the bone bridge itself, including the bridge failing to fuse or problems with the hardware used to hold it in place.
Nerve Management and Pain Prevention
One of the most significant advances in amputation surgery involves how nerves are handled. When a nerve is simply cut, it can form a painful knot of nerve tissue called a neuroma. A technique called targeted muscle reinnervation reroutes the cut nerve endings into nearby muscle, giving them somewhere to “signal” instead of forming these painful tangles.
In a study of over 200 patients, those who received this nerve technique had significantly lower rates and severity of both residual limb pain and phantom limb pain compared to those whose nerves were managed the traditional way. They also had higher rates of walking with a prosthesis. The procedure adds minimal time to the surgery and, in over 100 patients at one institution, produced no procedure-specific complications. Only two patients in that group later needed a second operation for nerve pain.
Phantom Limb Pain and Sensation
Over half of people who lose a limb experience phantom pain, the sensation that the missing part of the leg still hurts. This is different from residual limb pain, which is soreness or discomfort in the remaining stump itself. Many people also experience phantom sensations without pain: feelings of touch, pressure, itching, temperature changes, or vibrations in a foot that’s no longer there.
These experiences happen because the brain is reorganizing its sensory map after the amputation. The areas of the brain that used to receive signals from the lower leg and foot are still active, and they can misinterpret signals as pain or touch. Phantom pain tends to be most intense in the weeks and months after surgery, and for many people it gradually decreases over time, though it can persist for years in some cases. Treatment options range from medications to mirror therapy, where watching the intact leg move in a mirror can help retrain the brain’s perception.
Recovery and Early Rehabilitation
The first priority after surgery is wound healing. Sutures are typically removed within a few weeks, and compression wrapping begins immediately afterward to shape the residual limb and reduce swelling. How the limb is wrapped matters: pneumatic compression devices can speed up the shaping process compared to traditional elastic bandages, allowing an earlier transition to a prosthesis.
Preventing stiffness at the knee is critical during this period. Because the natural instinct is to keep the knee bent (it’s more comfortable), the joint can tighten into a permanent bent position called a flexion contracture. This makes prosthetic fitting and walking significantly harder. Keeping the knee straight when resting, lying face-down periodically, and doing range-of-motion exercises from the early days after surgery all help prevent this.
With elastic bandages, the residual limb typically takes six to eight weeks to stabilize in shape. With pneumatic compression, it can be ready in as little as three to six weeks. Once the limb has healed and its volume has stabilized, the fitting process for a prosthesis begins.
Prosthetic Options
Because the knee is preserved, people with a below-knee amputation have access to a wide range of prosthetic designs and generally achieve better walking ability than those with above-knee amputations. The prosthesis consists of a socket that fits over the residual limb, a suspension system that holds it in place, a pylon (the structural post), and a prosthetic foot.
Socket design has evolved considerably. Older designs concentrated pressure on specific areas like the tendon just below the kneecap (called a patellar tendon-bearing socket). Modern total surface-bearing sockets distribute pressure more evenly across the entire residual limb, which tends to be more comfortable. These are typically used with a silicone or gel liner that rolls directly onto the skin.
For suspension, several systems keep the prosthesis attached during movement. The most popular is a pin-and-lock system, where a small pin at the bottom of the silicone liner clicks into a lock on the socket. Suction and vacuum systems create an airtight seal between the liner and socket, which reduces how much the limb shifts inside the prosthesis. This minimizes friction, reduces pain at the end of the stump, and creates a more natural gait. The best system for any individual depends on their activity level, limb shape, and personal preference.
Activity Levels and Prosthetic Access
In the United States, insurance coverage for prosthetic components is tied to a functional classification system with five levels (K0 through K4) that describe a person’s current or potential mobility:
- K0: Unable to walk or transfer safely, even with a prosthesis.
- K1: Can walk on flat, even surfaces at a steady pace. This covers people who move around the house but don’t venture far outside.
- K2: Can handle low-level obstacles like curbs, stairs, and uneven ground. This describes someone who gets around the community but with some limitations.
- K3: Walks at varying speeds and can navigate most environments. This is a fully active community walker who may also exercise or work in a physically demanding job.
- K4: Exceeds typical walking demands, with high-impact activity. This includes athletes, active children, and adults with very physically demanding lifestyles.
Your assigned K-level determines which prosthetic components (particularly the foot and knee, if applicable) insurance will cover. Higher-performance feet with energy-storing carbon fiber blades, for example, are typically only approved for K3 and K4 users. A prosthetist and physiatrist work together to assess your level, and it can change over time as you progress through rehabilitation.
Long-Term Survival for Vascular Patients
For those who undergo a below-knee amputation due to vascular disease, the underlying circulation problems don’t stop at the amputation site. The five-year mortality rate for this group is about 16.7%, reflecting the serious systemic health challenges these patients face. In the first 30 days after surgery, the mortality rate is approximately 4.2%, rising to 7.5% by 90 days and 10.9% at one year.
Interestingly, patients with diabetes had somewhat better early survival than those without diabetes, likely because non-diabetic patients who reach the point of needing amputation often have more advanced cardiovascular disease. At five years, the rates converge: about 19% mortality for those with diabetes and 18% for those without. These numbers underscore that managing heart health, blood pressure, and blood sugar remains essential after amputation, not just for the remaining limb but for overall survival.