Replantation Golden Time and Microsurgical Reconstruction

Replantation golden time, the window for reattaching an amputated part, depends on the level of the amputation. Dr. Pradeep Kumar Singh's limits for warm ischaemia, when the part has not been properly preserved, are 4 hours for the arm, 6 hours for the forearm and 8 to 10 hours for fingers. Beyond those windows a proximal replant becomes unreliable, though microsurgery can still rebuild function by other routes.

Microsurgery is surgery on blood vessels and nerves only one to a few millimetres wide, performed under an operating microscope. It makes two things possible: reattaching a severed part (replantation), and moving a block of living tissue with its own artery and vein to a distant site, where the vessels are joined to local ones (a free flap). Dr. Pradeep Kumar Singh, Head - Cosmetic & Plastic Surgery, Artemis Hospitals, Gurugram, India, has used both to rebuild hands, jaws, a femur, a breast, a biceps and a penis. This article explains the time limits for replantation, the options when they have passed, and the free flap reconstructions behind those results. The complete guide to plastic surgery from reconstruction to aesthetics gives the overview of the specialty, the referral triggers and costs.

Replantation golden time by level of amputation

Replantation is the surgical reattachment of a completely amputated part: bone fixation, then repair of arteries, veins, tendons and nerves. Dr. Singh's golden periods, counted from the moment of injury to the start of reconstruction, are:

These limits apply to warm ischaemia, where the amputated part was not properly preserved, and they are deliberately conservative. Widely cited limits are about 6 hours of warm ischaemia for parts that contain muscle and about 12 hours for digits, so a finger should not be refused replantation on time alone at 10 hours. Cold ischaemia, where the part has been cooled, extends the tolerance, to about 12 hours for major parts and 24 hours or more for digits. The established way to preserve an amputated part is to wrap it in gauze moistened with saline, seal it in a plastic bag and place the bag on ice, never letting the tissue touch the ice directly.

The difference between levels reflects tissue biology. Skeletal muscle is the tissue least tolerant of lost blood supply, and an arm or forearm contains a large mass of it, whereas a finger contains almost none. The more muscle in the amputated part, the shorter the safe window.

Why proximal replantation should not be stretched

Early in his practice, Dr. Singh attempted proximal replantations at 10 and 12 hours. The post-operative course was very unstable, and he took the lesson: a proximal replantation should be attempted within 4 hours, 6 at most, and not beyond.

His results within and near those limits show what is achievable:

• Hand replantation at seven hours. A patient reached him seven hours after an industrial accident amputated the whole hand, having been delayed by traffic and turned away by hospitals that declined to attempt replantation. Dr. Singh replanted the hand. The patient recovered fairly good sensation and some movement, a reasonable result given the delay.
• Multiple finger replantation. After another industrial accident, two of three amputated fingers were saved.
• Toe revascularisation in a child. Revascularisation is the repair of the vessels of an injured part to restore its blood flow. Dr. Singh performed one on a child's amputated toe.

His first hospital stood among factories, so injuries of this kind made up much of his early work.

Options after the replantation window: toe-to-hand transfer and prostheses

Patients who miss the replantation window can still benefit months later, and Dr. Singh is clear on this. In cross-border care, a patient often cannot reach a replantation surgeon in time, and a finger or hand is lost or poorly repaired. Four options remain.

1. Toe-to-hand transfer. When a finger was amputated and not reconstructed, a toe is transferred to the hand as a free flap, with its vessels, nerves and tendons joined to those of the hand. It gives a good degree of functional recovery.
2. Osseointegrated prostheses. As cosmetic rehabilitation, his department offers permanent prostheses for fingers and hands that are anchored directly into the bone.
3. Bionic hands. Myoelectric prostheses, which use electrical signals from the patient's remaining muscles to drive the hand, are another option.
4. Hand transplantation. A few centres have begun cadaveric hand transplantation, and at the time of the session Dr. Singh's department planned to start a hand transplant programme within about a year to eighteen months. For international patients this route is ruled out: allocation of deceased-donor organs and tissues in India gives priority to Indian citizens.

Free fibula flap reconstruction: rebuilding bone with living bone

A free fibula flap rebuilds missing bone with a living segment of the patient's own fibula, the thin outer bone of the lower leg. The fibula carries little weight, so a long segment can be removed with its own artery and veins (the peroneal vessels) and transferred as a vascularised graft. Unlike a conventional bone graft, it stays alive, heals like a fracture and can remodel. Dr. Singh uses it for four quite different problems.

Jaw reconstruction after ameloblastoma

In a young patient with an ameloblastoma, a locally aggressive benign tumour of the jaw, the whole mandible had to be removed. Dr. Singh rebuilt it with a free fibula flap, shaped to the curve of the jaw, and achieved a good jaw contour.

Mandible reconstruction with immediate dental implants

In another patient, after cancer surgery on the mandible, he placed dental implants into the fibula at the same operation that rebuilt the jaw. The patient later had teeth fixed onto the implants.

Distal femur osteosarcoma in a growing child

A case Dr. Singh singled out as special was a young boy with an osteosarcoma (a bone cancer) at the lower end of the femur, with the epiphysis, the end of the bone, also involved. The orthopaedic oncologists planned to remove the lower two-thirds of the femur together with the growth plate, which in a child would normally mean a leg that stops growing.

Dr. Singh harvested the fibula from the opposite leg together with its growth plate at the head of the fibula, so that the reconstructed bone could keep growing. The flap was raised on a dual blood supply: the peroneal artery fed the shaft of the fibula, and a branch of the anterior tibial artery fed its head and growth plate.

The construct combined two established limb-salvage techniques. The resected femur was sterilised with a high single dose of radiation outside the body (extracorporeal irradiation) and reimplanted, and the living fibula was placed inside it, the approach known as the Capanna technique. The dead but structurally sound irradiated bone provides strength; the vascularised fibula inside it provides blood supply and healing.

The fibula integrated well with the surrounding bone. Two years after the reconstruction the child had a good range of motion and was walking without any apparent shortening of the femur.

Avascular necrosis of the femoral head

A 12-year-old developed avascular necrosis (bone death from lost blood supply) of the femoral head after an injury. The dead bone in the head of the femur was reamed out and a vascularised free fibula was placed inside the femoral head to bring in a new blood supply. After surgery the child had a full range of motion without pain and without any limb length discrepancy, and was walking and jumping around.

Limb salvage after a crush injury of the foot

A patient with a severe crush injury of the foot had been advised amputation at several hospitals but insisted on reconstruction. Dr. Singh reconstructed the foot. One year later the patient had a good range of motion and was walking normally.

Breast reconstruction with DIEP and latissimus dorsi flaps, and chest wall repair

Free and pedicled flaps also rebuild soft tissue after cancer and trauma.

• Bilateral breast reconstruction after prophylactic mastectomy. In a woman who had both breasts removed to reduce cancer risk, Dr. Singh reconstructed both breasts with latissimus dorsi flaps, using the broad back muscle on each side.
• DIEP flap breast reconstruction. In another patient he rebuilt the breast with a deep inferior epigastric perforator (DIEP) flap, which takes skin and fat from the lower abdomen with its blood vessels but spares the abdominal muscle. Good symmetry was achieved.
• Chest wall reconstruction after trauma. A traumatic chest wall defect was covered with a free flap.

The timing of breast reconstruction relative to mastectomy and cancer treatment is covered in breast reconstruction after mastectomy: options and timing, and indicative partner-hospital quotations are on the breast reconstruction surgery cost page.

Penile reconstruction after trauma and cancer

Dr. Singh has reconstructed the penis in men who lost it to trauma and to cancer surgery. After a traumatic penile amputation he used a radial artery forearm flap, the thin, pliable skin of the forearm raised on the radial artery and rolled into a tube. A second patient, whose penis had been amputated during cancer surgery, also underwent flap reconstruction with a very good result.

Functional free muscle transfer to restore elbow flexion

A free flap can restore movement as well as cover. A patient with a recurrent soft tissue sarcoma of the arm had lost the whole biceps to tumour surgery. Dr. Singh transferred the latissimus dorsi muscle from the opposite side as a free flap, joined its artery and vein to vessels in the arm, and connected its nerve to a few motor fascicles (bundles of nerve fibres) of the ulnar nerve so that the transferred muscle would contract and bend the elbow.

Reconstruction without microsurgery: tissue expansion

Not every reconstruction needs a microscope. In a patient whose scalp had been left with a grafted raw area after burns, Dr. Singh used tissue expansion: an expander placed under neighbouring healthy scalp is gradually inflated to grow extra hair-bearing skin, which is then advanced to replace the scar. Cleft lip and cleft palate repair, the standard reconstructive operations of residency training, also sit in this category.

Microsurgery success rate, complications and cost

Over the last two years, Dr. Singh's department has had a success rate of about 99% for microsurgical procedures: only two procedures did not turn out as expected. Complications, which depend largely on the patient's own risk factors, and the cost of microvascular reconstruction are set out in the complete guide. Microsurgery also underpins the two newest areas of his plastic and reconstructive surgery practice, lymphoedema surgery and brachial plexus nerve transfer. Doctors' questions on golden time and late presentation are answered in the Live Discussion.