Introduction
An ankle joint amputation (removal) is referred to as a Syme amputation or Syme disarticulation. In order to put weight on the leg without a prosthesis (artificial limb), the foot is removed, but the heel pad is retained. A Syme amputation aims to create a painless, functioning limb by removing diseased tissue or an unusable foot.
What Are the Indications and Contraindications of Syme Ankle Disarticulation?
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Indications:
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Someone who needs to have most of their foot amputated since it has lost most of its viability due to a variety of conditions, such as diabetic foot infection.
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Trauma, such as a foot crush injury, cannot be repaired.
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When a patient's remaining functional heel pad makes partial foot amputation impossible.
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Specific tumors.
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Deficits and deformities that are present from birth, such as a proximal focal femoral deficiency, fibular hemimelia (short or missing one of the two bones in the lower leg), and congenital pseudarthrosis of the tibia. Diabetes is the most prevalent underlying condition, followed by trauma and arteriosclerotic peripheral vascular disease (circulatory disease).
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Only when the patient can be a functional walker as an alternative to limb salvage amputation is capable of producing a better functional and desirable outcome.
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Contraindications:
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Wheelchair-bound or otherwise immobile patients.
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The absence of an intact and viable heel pad.
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Compromised posterior skin over the Achilles tendon (connecting tendon of the calf muscle and heel).
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Severe foot infections that have spread too far proximally and affected the area of the heel.
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Partial foot amputation patients who can be fitted with shoe modifications rather than prostheses.
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What Are the Advantages and Disadvantages of Syme Ankle Disarticulation?
As with many procedures, choosing the right patient is the most crucial factor in determining a favorable outcome of the Syme amputation. The patient will receive preoperative counseling, and it is crucial that they understand the benefits and drawbacks of the procedure.
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Advantages:
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The mechanical advantage is the longer lever given to the quadriceps muscles (thigh muscle) and knee joint, which results in lower energy expenditure during walking compared to patients with a more proximal amputation. This is relevant for patients with underlying chronic debilitating diseases like diabetes or peripheral vascular disease (circulatory disorder).
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Compared to a below-knee amputee, patients need less training and rehabilitation to become mobile. Patients do not need to be admitted to a rehabilitation facility for gait training because training to put on and take off the prosthesis is easy.
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The distal stump (residual limb) is protected by thick plantar skin (skin over the sole) and the heel pad and can support weight bearing, with some of the stress being supported by specialized tissue and the remainder being distributed by the proximal tibial metaphysis (bone near the knee). When getting up in the middle of the night to use the restroom, some patients claim that their weight is placed directly on the stump.
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Disadvantages:
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Technically more challenging than amputation below the knee.
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Possibility for delayed wound healing in people who have acceptable but insufficient blood flow at the ankle level; blood flow and skin condition might be improved closer to the site.
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There is a possibility of heel dislocation, although reduced by keeping the heel pad.
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In terms of aesthetics, the stump may have huge, superfluous bulbs of soft tissue.
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In contrast to below-the-knee amputations, which are carried out more frequently, prosthetists may have less experience filling prostheses.
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What Are the Evaluation Criteria for Syme Ankle Disarticulation?
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Sufficient Vascularity: Association between successful Syme amputation and palpable posterior pulses. The majority of patients who need this surgery have diabetes, vascular issues, or both. In order to check limb perfusion, arterial Doppler ultrasound is widely accessible and simple to use. It is a screening test, not a conclusive assessment of perfusion. Regarding tissue perfusion, other technologies, such as transcutaneous oxygen monitoring and arteriography, are more reliable.
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Vascular Surgeon Opinion: Before doing this procedure, a consultation with a vascular surgeon can be beneficial. Procedures for revascularization can be necessary. The most important thing is that the heel pad, which is primarily fed by branches of the posterior tibial artery, receives enough circulation.
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Vascular Inflow: For wounds to heal, there must be sufficient vascular inflow. A transcutaneous partial pressure of oxygen (TcpO2) of between 20 and 30 mm Hg or higher, palpable dorsalis pedis or posterior tibial arterial pulses, an ultrasound ankle-brachial index of 0.5 or better, or ultrasound Doppler toe pressures between 20 and 30 mm Hg can all be used to confirm the diagnosis. Once localized cellulitis and infection have been treated, the decision regarding the amount of amputation may change since transcutaneous oxygen tension can be abnormally low in the presence of infection.
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Forefoot Gangrene: Failure occurs in individuals with forefoot gangrene (severe foot ulcers) unless enough arterial inflow has been restored through bypass surgery or angioplasty.
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Skin’s Integrity: Documentation should be made of the skin's integrity and the severity of any skin ulcerations.
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Preparation of Surrounding Tissue: Before amputation, it is important to achieve the best condition for the surrounding tissue, perform a debridement, and resolve any localized or systemic sepsis brought on by the spread of the foot infection.
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Joints: Involvement of the joints, bones, and deep soft tissues underneath. No evidence of osteomyelitis (bone infection) in the talus, fibula, or distal tibia.
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Nutritional Status: Nutritional data are measured using serum albumin. 3.0 gm/dL is the acceptable threshold value. In the context of infection, renal failure, and polytrauma, it can fall to very low levels. Following sufficient surgical debridement and culture-specific antibiotic therapy, nutritional support—typically oral—is started. As the serum albumin level approaches the 3.0 gm/dL limit, definitive surgery can be done. Both distal bypass surgery and amputation at the foot and ankle have poorer success rates in patients with renal failure and low serum albumin levels. These patients receive more proximal-level amputation therapy.
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Total Lymphocyte Count: Although its prognostic value for amputations has been called into question, total lymphocyte count has been utilized as a measure of cell-mediated immunity.
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The effectiveness of the procedure depends on the patient's preoperative education, which includes consultation with the amputation service.
How Is Syme Ankle Disarticulation Done?
Orthopedic foot and ankle surgeons carry out this procedure when the patient is unconscious and under general anesthesia. Surgery can be performed under spinal anesthesia or a leg nerve block with sedatives for individuals whose risk factors make general anesthesia risky. Blood loss can be reduced with the aid of a tourniquet (to halt bleeding from a major wound, tight bands are tied around the arm or leg).
At the joint of the foot and ankle, an opening is created. The heel pad is safeguarded. The soft tissues covering the foot bones are severed from the ligaments and tendons connecting them to the ankle. Besides being tied up, arteries are also severed. To have a flat surface at the end of the leg once the wound is closed, the bony prominences at the ankle are removed. Sometimes, a drain is utilized to help prevent a blood pool from growing deep in the tissue, which could lead to the surgery failing. Finally, a cast and a large, soft dressing are applied.
How Is the Recovery After Syme Ankle Disarticulation?
Patients are observed in the recovery area for a short while following surgery. Once the wound has healed, patients can begin walking. The length of a hospital stay can change. After surgery, patients who can get around comfortably on one leg with crutches or a front-wheel walker and have assistance at home may return home. Before returning home, patients who require more help or regular physical therapy may first check into a rehabilitation facility, transitional care unit, or skilled nursing facility.
When the incision has fully healed, skin staples or sutures are taken out. Compression stockings can reduce swelling, although it is common to feel it for up to a year following surgery.
An expert prosthetist creates an artificial limb (prosthesis) for the lower leg and stump once the incision has healed and the majority of the leg swelling has subsided. For the prosthesis to fit well, several adjustments could be necessary. Further therapy is provided once the prosthesis is complete to teach the patient how to walk comfortably while using it.
What Are the Complications of Syme Ankle Disarticulation Surgery?
The biggest issue is the wound's inability to heal. This may result in infection, tissue loss, and the requirement for a higher-level amputation. A further potential issue following this treatment is the excessive motion of the heel pad stump (residual limb), which can result in areas of increased pressure and, eventually, ulcers near the bottom of the amputation. Sometimes, local wound care and prosthesis modification can be used to treat these ulcers. Further surgery should be performed to remove the bony prominence and promote healing if it is the cause of the ulcer.
Many patients initially experience the feeling that their foot is still there (phantom limb sensation). This is not painful and is usual. However, some patients can experience discomfort where the main nerves are severed (phantom limb pain).
Conclusion
Even in individuals with diabetes, the Syme ankle disarticulation offers a long-lasting, reliable residual limb. In situations when there are no infections or vascular issues, traditional treatment continues to be the best option. Due to the heel's continued retention and superior weight-bearing capabilities, the Syme ankle disarticulation results in a partial foot ablation. The Syme level of function is superior to any other major lower limb amputation.
