Background

A trans metatarsal amputation (TMA) is a surgical procedure that involves the removal of one or more metatarsal bones in the foot. Metatarsal bones are the long bones in the middle part of the foot, and a transmetatarsal amputation typically involves the removal of the metatarsal heads and corresponding toes. This procedure is often considered when there is severe infection, non-healing ulcers, or other conditions that threaten the health and function of the foot. 

Severe infections in the foot, especially those that do not respond to conservative treatments, may necessitate amputation to prevent the spread of infection. Poor blood circulation in the lower extremities can lead to non-healing wounds and tissue death, making amputation a potential treatment option. 

Peripheral neuropathy, often associated with conditions like diabetes, can lead to the development of foot ulcers that may not heal, increasing the risk of infection. 

The goal of a transmetatarsal amputation is to remove the affected tissue while preserving as much of the foot’s function as possible. Unlike more extensive amputations, such as below-the-knee or above-the-knee amputations, a transmetatarsal amputation allows for better mobility and weight-bearing. 

Indications

• Severe Infections: When a foot infection becomes severe and does not respond to conservative treatments, such as antibiotics or wound care, amputation may be necessary to prevent the spread of infection to other parts of the body. 
• Non-Healing Ulcers: Chronic, non-healing ulcers on foot, especially those associated with conditions like diabetes or peripheral vascular disease, may be indications for transmetatarsal amputation. The goal is to remove the non-healing tissue and reduce the risk of infection. 
• Ischemia (Poor Blood Circulation): Conditions that lead to poor blood circulation in the foot, such as peripheral arterial disease (PAD), can result in tissue damage and non-healing wounds. In cases where revascularization procedures are not feasible or successful, transmetatarsal amputation may be considered to remove compromised tissue. 
• Necrosis (Tissue Death): Necrosis, or death of tissue, can occur due to various reasons, including reduced blood flow or severe infection. Transmetatarsal amputation may be indicated when there is extensive necrosis that threatens the viability of the foot. 
• Charcot Foot Deformity: Charcot foot is a condition characterized by weakened bones in the foot, leading to fractures and deformities. In cases where Charcot foot deformity is severe and poses a risk of ulceration or infection, transmetatarsal amputation may be considered. 
• Peripheral Neuropathy: Peripheral neuropathy, often associated with conditions like diabetes, can result in the loss of sensation in the feet. Patients with neuropathy may be prone to developing ulcers and infections, and in cases of severe complications, amputation may be necessary. 
• Traumatic Injuries: Traumatic injuries, such as crush injuries or severe fractures, may lead to irreparable damage to the foot. In some cases, transmetatarsal amputation may be indicated to address the trauma and promote healing. 

Contraindications

• General Medical Unfitness: Patients who are not medically stable or fit for surgery may be considered poor candidates for trans metatarsal amputation. This includes individuals with significant cardiovascular or respiratory compromise that increases the risk of complications during and after surgery. 
• Poor Overall Prognosis: If a patient has a limited life expectancy due to advanced systemic illness or other factors, the potential benefits of a transmetatarsal amputation may be outweighed by the overall prognosis. 
• Extensive Soft Tissue Involvement: If there is extensive soft tissue involvement, such as widespread infection or necrosis that extends beyond the metatarsals, a transmetatarsal amputation may not be sufficient to address the condition. 
• Lack of Vascular Support: Adequate blood supply is crucial for wound healing and the overall success of the amputation. If there is insufficient vascular support to the foot, and revascularization procedures are not possible or successful, transmetatarsal amputation may not be recommended. 

• Uncontrolled Systemic Infection: If there is evidence of uncontrolled systemic infection, performing a surgical procedure like transmetatarsal amputation may exacerbate the infection or lead to complications. In such cases, addressing the systemic infection is a priority before considering amputation. 
• Unstable or Charcot Foot Deformity: In cases of an unstable or severe Charcot foot deformity, where the bones are fragile and prone to fractures, a transmetatarsal amputation may not be the optimal solution. Addressing the underlying deformity and stabilizing the foot may be necessary before considering amputation. 

Outcomes

• Wound Healing: Successful wound healing is a primary goal of transmetatarsal amputation. However, individuals with compromised vascular supply or diabetes may face challenges in wound healing. Close monitoring and appropriate wound care are essential to prevent complications such as infection. 
• Functional Ambulation: The preservation of the metatarsals aims to maintain functional foot length and support weight-bearing. Successful transmetatarsal amputation can allow for improved mobility and ambulation compared to more extensive amputations. 
• Prevention of Infection Spread: Transmetatarsal amputation is often performed to prevent the spread of infection from the foot to other parts of the body. Successful amputation can eliminate the source of infection and contribute to overall health. 
• Pain Management: Depending on the underlying condition and the success of the surgical procedure, transmetatarsal amputation can alleviate pain associated with conditions such as non-healing ulcers, infection, or necrosis. 
• Prosthetic Use: In cases where the amputation results in a functional residual limb, individuals may be candidates for prosthetic devices. The use of prosthetics can significantly enhance mobility and quality of life for those who have undergone transmetatarsal amputation. 
• Rehabilitation Success: Rehabilitation plays a crucial role in the outcomes of transmetatarsal amputation. Physical therapy and rehabilitation programs aim to improve strength, balance, and coordination to enhance functional independence. 
• Complications: Complications can occur, and they may include delayed wound healing, infection, neuroma formation (tangled nerve bundles), and skin breakdown. Careful postoperative monitoring and prompt intervention can help manage and reduce these complications. 
• Psychosocial Impact: Adjusting to life after transmetatarsal amputation can have psychosocial implications. Support from healthcare professionals, rehabilitation specialists, and mental health professionals can assist individuals in adapting to the changes and maintaining a positive outlook. 
• Long-Term Follow-up: Long-term follow-up is important to assess the ongoing success of the amputation and to address any late-onset complications or issues. This may involve regular check-ups with healthcare providers and ongoing rehabilitation. 
• Patient Satisfaction: Patient satisfaction is a subjective but crucial aspect of the outcomes. Factors such as pain relief, improved mobility, and the ability to engage in daily activities contribute to overall satisfaction with the procedure. 

Equipment

• Scalpel with Blades: The scalpel is a precision cutting tool used to make incisions. Different blade types may be chosen based on the surgeon’s preference and the specific requirements of the procedure. 
• Dissection and Cutting Scissors: Dissection and cutting scissors are employed to cut soft tissues during the procedure. They come in various shapes and sizes to accommodate different anatomical structures. 
• Retractors and Handheld Clamps: Retractors are used to hold back tissues, providing the surgeon with a clear view of the surgical field. Handheld clamps assist in grasping and holding tissues securely during dissection. 
• Needle Holders, Suture Material, and Forceps: Needle holders are used to grasp and manipulate needles during the suturing process. A variety of suture materials, both absorbable and nonabsorbable, may be used to close the incisions. Forceps, including fine and toothed varieties, are used for tissue manipulation. 
• Diathermy Device: A diathermy device, often referred to as an electrocautery or electrocautery unit, is used for cutting and coagulating tissues by applying a high-frequency electrical current. It aids in hemostasis and tissue dissection. 

• Bone Instruments (e.g., Saw, Bone Nibblers, Osteotomes, Mallet, and Curettes): Various instruments are required for bone removal during transmetatarsal amputation. A saw may be used to cut through the metatarsal bones. Bone nibblers help remove smaller pieces of bone, osteotomes are used for controlled bone cutting, a mallet may be used for impact, and curettes assist in cleaning the bone edges. 
• Irrigation: Irrigation is an essential part of the surgical process, helping to keep the surgical field clear of debris and maintaining a clear view for the surgeon. Sterile saline or another irrigating solution is commonly used. 

Patient Preparation

• Anesthesia: The choice between general anesthesia or regional anesthesia depends on the patient’s overall health and anesthetic risk. Both options have their advantages, and the decision is often made in consultation with the anesthesia team. 
• Patient Positioning: The patient is placed in a supine position on the operating table. This position allows the surgical team optimal access to the foot for the amputation procedure. 
• Tourniquet Application: A tourniquet is placed around the upper thigh. The purpose of the tourniquet is to temporarily restrict blood flow to the lower limb during the surgery, facilitating a bloodless surgical field and improving visibility for the surgeon. 
• Wool and Adhesive Application: Wool is placed under the tourniquet cuff, likely for cushioning and to provide a barrier between the tourniquet and the patient’s skin. Adhesive is applied to secure the tourniquet in place. This is important for maintaining the appropriate pressure and preventing movement during the procedure. 
• Sterile Preparation: Full sterile preparation is crucial to minimize the risk of infection. This involves using antimicrobial wash and disinfectant to clean the surgical site. Maintaining a sterile environment is essential for preventing postoperative complications. 
• Protection of Healthy Tissue: The ulcerated area is covered with a surgical glove to protect it during the procedure. This step helps safeguard the surrounding healthy tissue and prevent contamination of the wound. 
• Elevation of the Leg: The leg is elevated before the tourniquet is inflated. Elevation helps to reduce blood flow to the limb, and the subsequent inflation of the tourniquet further restricts blood flow during the surgery. 
• Milking Blood Out of the Limb: The description mentions “milking” blood out of the limb. This may involve manual manipulation to assist in venous drainage before the tourniquet is applied. Improving venous drainage can contribute to a more precise surgical field. 
• Tourniquet Inflation: The tourniquet cuff is inflated to a specific pressure (usually 200-300 mm Hg). This pressure is sufficient to temporarily stop arterial blood flow to the lower limb, creating a bloodless field for the surgeon to work. 

Follow up and Monitoring

Rehabilitation after transmetatarsal amputation (TMA) is vital for optimal mobility and patient well-being. Key considerations include: 

Load Distribution and Pressure Management: 

• Emphasize offloading pressure on the surgical site during initial healing. 
• Consider assistive devices like crutches to reduce weight-bearing on the affected foot. 

Increased Fall Risk in Neuropathic Patients: 

• Conduct regular sensory checks, especially in diabetic or neuropathic patients. 
• Provide education on foot care and strategies to prevent falls. 

Decreased Plantarflexion and Stability: 

• Implement exercises to improve strength, balance, and proprioception. 
• Use temporary postoperative devices (e.g., walking splints) for initial support. 

Support Movement and Overall Limb Pattern: 

• Include physical therapy targeting hip, knee, and ankle extensor muscles. 
• Customize rehabilitation plans based on individual needs and abilities. 

Orthotic Devices: 

• Use temporary devices initially (e.g., walking splints). 
• Introduce definitive footwear after wound healing. 
• Consider custom-made footwear for long-term biomechanical support. 

Regular Sensory Checks and Patient Education: 

• Monitor sensory function, especially in diabetic or neuropathic patients. 
• Educate patients on foot care, infection signs, and the importance of prompt medical attention. 

Temporary and Definitive Footwear: 

• Use temporary devices like plaster or walking splints in the initial recovery. 
• Introduce definitive footwear after the surgical wound heals. 
• Consider custom-made footwear, such as shoes with steel implants, for long-term support. 

TECHNIQUE

The transmetatarsal amputation (TMA) technique involves the surgical removal of the metatarsal bones of the foot while preserving as much healthy tissue as possible. Here is a general outline of the TMA procedure: 

Preoperative Steps: 

• Patient Positioning: Place the patient in a supine position on the operating table, with the affected leg exposed and appropriately positioned for surgical access. 
• Anesthesia: Administer either general anesthesia or regional anesthesia, depending on the patient’s health and the surgical team’s preference. 

Surgical Procedure: 

• Incision: The surgeon makes a curved or straight incision on the dorsal (upper) aspect of the foot, typically starting proximal to the metatarsophalangeal joints and extending towards the midfoot. 
• Soft Tissue Dissection: Dissect through the soft tissues, including skin, subcutaneous tissue, and muscle, to expose the metatarsal bones. 
• Bone Sectioning: Use a saw or bone-cutting instrument to section the metatarsal bones. The number of metatarsals removed depends on the extent of the pathology, but TMA usually involves removing several metatarsals. 
• Careful Hemostasis: Achieve meticulous hemostasis to minimize bleeding during and after the procedure. Electrocautery or other hemostatic techniques may be employed. 
• Closure of Soft Tissues: Close the soft tissues in layers, ensuring proper alignment and closure to promote optimal wound healing. Deep layers may be closed with absorbable sutures, and the skin may be closed with nonabsorbable sutures or staples. 
• Dressing Application: Apply a sterile dressing to the surgical site to protect the wound and facilitate healing. 

Postoperative Care: 

• Monitoring: Monitor the patient in the recovery room and assess vital signs. Check for any signs of bleeding or infection. 
• Pain Management: Provide appropriate pain management to ensure the patient’s comfort during the recovery period. 
• Early Mobilization: Encourage early mobilization and weight-bearing as tolerated, with the aid of assistive devices. Physical therapy may be initiated to facilitate rehabilitation. 
• Wound Care: Instruct the patient on proper wound care, including keeping the incision site clean and dry. Monitor for signs of infection. 
• Prosthetic Evaluation: Consider prosthetic evaluation and fitting, especially if the patient is a candidate for a prosthetic limb. 
• Follow-up: Schedule follow-up appointments to monitor the healing process and address any concerns or complications. 

Complications

• Infection: Surgical wounds are susceptible to infection. Infections can delay wound healing and, in severe cases, may lead to systemic infection (sepsis). Proper preoperative and postoperative care, including antibiotic administration, is crucial in minimizing infection risk. 
• Delayed Wound Healing: Healing of the surgical wound may be delayed, especially in individuals with compromised vascular supply or other factors that affect wound healing. Close monitoring and appropriate wound care are essential. 

• Wound Dehiscence: Wound dehiscence refers to the separation of wound edges. This can occur due to factors such as infection, poor wound closure, or excessive stress on the incision site. It may necessitate additional interventions to promote healing. 
• Skin Necrosis: Inadequate blood supply to the skin flaps may result in skin necrosis. This can compromise the overall success of the amputation and may require additional surgical procedures to address. 
• Neuroma Formation: Neuromas, or tangled nerve bundles, may develop at the site of amputation. These can cause pain or discomfort and may require further treatment. 
• Phantom Limb Pain: Some individuals may experience phantom limb pain, a sensation of pain or discomfort in the amputated limb. This can be challenging to manage and may persist in the postoperative period. 
• Stump Complications: Issues related to the residual limb (stump) can include pressure sores, skin breakdown, or problems with prosthetic fitting. Proper stump care and regular follow-up are essential. 
• Prosthetic Issues: Patients using prosthetic limbs may face challenges such as fit issues, discomfort, or difficulty adjusting to the prosthetic. Regular prosthetic evaluations and adjustments may be necessary. 

References

transmetatarsal amputation.ncbi.nlm.nih 

Evolution of Principles.jfasap 

References

transmetatarsal amputation.ncbi.nlm.nih 

Evolution of Principles.jfasap