Definition & Overview
Below the knee amputations, also known as trans-tibial amputations, are surgical procedures wherein one or both the lower limbs are removed from below the knee. It is classified as a lower-limb amputation and considered as the most common type of amputation surgery in general.
Amputations often become necessary when the limb is severely damaged due to disease or traumatic injury. The goal of the procedure is to remove all damaged tissues of the limb while retaining the healthy tissues as much as possible.
Who Should Undergo and Expected Results
Below the knee amputation can be recommended for patients who have severely diseased or damaged lower limbs that can no longer be treated or saved using non-surgical or other surgical methods. Diseases that may warrant the procedure include:
- Peripheral vascular disease – This condition is caused by the lack of blood circulation in the lower limb, which restricts healing and proper immune response. Since the limb is unable to obtain enough oxygen and nutrients through blood, it becomes more susceptible to infection. 60 to 70 percent of all trans-tibial amputations are attributed to peripheral vascular disease.
- Foot ulcer
- Infection of open wounds – Infection of the lower limbs, if left untreated or unable to heal due to an underlying health problem, may spread to the bone and become a threat to the patient’s life.
- Severe trauma to the lower leg due to a traumatic injury
- Cancerous tumour on the bone or in the limb muscles
- Neuroma or thickened nerve tissue
Studies show that up to 60% of all amputations can be prevented. For example, amputations due to diabetes complications can be avoided by properly and conscientiously managing the circulatory problems that it causes. Nevertheless, there are some conditions, such as those related to traumatic injuries, wherein amputations cannot be prevented.
After the procedure, the patient has to undergo physical therapy, during which he will be taught how to exercise to build the strength and improve the flexibility of his hips and knees. These exercises begin with mild and gentle stretching exercises to improve range of motion. As the patient progresses through his recovery, he is taught how to perform normal everyday movements, such as rolling in bed, sitting on the side of his bed, or moving from the bed to a chair.
Amputees may also require pain management assistance. Various techniques can be used, including:
- Manual therapy, which aims to relieve pain by improving circulation with the help of joint manipulation and massage
- Stump management
- Desensitisation, which aims to reduce the skin’s sensitivity or responses to various stimuli
- Electrical stimulation
- Transcutaneous electrical nerve stimulation (TENS), wherein the skin is gently stimulated using electrical energy to block nerve signals
When the patient is fully recovered from the surgery, he will receive training on how to use assistive devices such as crutches or walkers as well as prosthetic training so he can move confidently using a prosthetic limb.
How is the Procedure Performed?
The procedure can be performed under either general or spinal anaesthesia, the latter of which keeps the patient awake but numb from the waist down. The surgeon then makes an incision and removes all diseased or damaged tissues as well as crushed bones before sealing off all blood vessels and nerves. The remaining muscles are then cut in a way that the stump can accommodate a prosthetic limb. The wound is then sewn and covered with sterile dressings. A drain is also used to allow excess fluid to leak out to prevent infection.
Amputees typically have to stay in the hospital for 5 to 14 days following the procedure. They will be given pain medications as well as antibiotics to help prevent infections. The wound on the stump can take anywhere between four to eight weeks to heal.
Possible Risks and Complications
As a major surgical procedure, below the knee amputations are associated with a number of serious risks and post-surgical complications, such as:
- Contractures – These occur when the soft tissues of the surgical limb tighten and restrict joint motion. If not addressed early, these can become a permanent problem and can keep a patient from using a prosthesis.
- Phantom pain – Some patients may report feeling a sense of pain in the amputated limb.
- Phantom limb – Some patients may also feel like the amputated limb is still there.
- Grief – Some patients may feel grief over the lost limb. This is why many of them undergo post-surgical counselling to help them cope with the emotional effects of losing a limb permanently.
Patients are also at risk of the common complications associated with most major surgeries, such as blood loss, blood clots, and adverse reactions to the anaesthesia.
Furthermore, if the amputation site fails to heal properly as expected, it is possible for the patient to require another amputation procedure. The risk of complications is higher among patients who are chronic smokers, chronic drinkers, and have underlying diseases such as diabetes.
Ertl J. “Lower-Extremity Amputations.” Medscape. http://emedicine.medscape.com/article/1232102-overview
Muilenburg A., Wilson B. Jr. “A manual for below-knee (trans-tibial) amputees.” http://www.oandp.com/resources/patientinfo/manuals/bkindex.htm
Hoar CS Jr., Torres J. “Evaluation of below-the-knee amputation in the treatment of diabetic gangrene.” N Eng J Med 1962; 266:440-443.http://www.nejm.org/doi/full/10.1056/NEJM196203012660905