Medical professionals who assess patients with forearm amputation must be aware of the “life before limb” principle that unreasonable limb replantation can lead to patient death. Therefore, for patients in the emergency department, advanced trauma and life support systems, typically associated with traumatic injuries, should be provided. This helps identify accompanying injuries and diseases and, most importantly, maintains hemodynamic stability. This also helps determine the need for replantation while considering the ischemic time, degree of contamination, and severity of injuries. A tourniquet can be applied to amputated limbs to minimize blood loss; however, there is a risk of metabolic acidosis due to ischemic injury in the amputated part [11,12]. Once patients have achieved hemodynamic stability, radiologic assessment is necessary, as well as an evaluation of whole-body status, age, occupation, and injury characteristics to determine the need for replantation surgery [11,12].

The goals of replantation are function preservation, independence of movement, and chronic pain prevention [12]. In particular, recovering protective sensations in the upper limb significantly affect patient satisfaction, increases the efficacy of rehabilitation, and promotes functional recovery of the digits. In addition, the recovery of nerves and muscles is necessary for the resumption of functional capacity. However, this is difficult to achieve. Surgeons and patients undergoing replantation of forearm amputation should be aware that the part of the limb being operated on will never be the same as the normal limb. This surgery was performed to improve functional, aesthetic, and psychological outcomes [13].

Surgical indications for forearm replantation are similar to those for the replantation of an amputated digit. When deciding whether to perform replantation, the patient’s age, injury mechanism, degree of injury, functional outcomes, and motivation for replantation should be considered before surgery [5]. Replantation cannot be performed for severely crushed or mangled injuries, multilevel amputation, prolonged normothermic ischemic time, or in cases of accompanying life-threatening injuries [14].

Debridement should be performed on the amputated limb. Contaminated tissues or foreign bodies should be removed as quickly as possible without interfering with function. Incisions should be made such that the anastomosis site remains covered at the end of all procedures. If the contamination level of the injuries is high, the major nerves and arteries should be tagged and debrided to minimize the loss of non-injured nerves or vessels [7,14].

During debridement, the small and minor vessels of the muscle should be thoroughly ligated to control bleeding after the tourniquet is released. Additional debridement is necessary after connecting the artery to reduce contamination after final replantation.

Bone shortening is mandatory for the successful replantation of forearm amputations. When performing bone shortening, the goal is to perform primary repair of the blood vessels and nerves with minimal nerve grafts or vein grafts. This procedure relieves the strain on the artery to be repaired and prevents possible secondary conditions caused by the thrombus, such as arterial spasm and arterial insufficiency.

There is no literature on the maximum possible length that can be considered for shortening, but a 5 to 10-cm shortening in the upper extremity is possible. Because replantation should be performed within a short time, bone fixation using a simple method is preferred. Internal fixation is a technical option involving the use of a Kirschner-wire or plate, depending on the osteotomy site. In the case of a radioulnar fracture at a different site, one of the fractured bones can be fixed in a primary operation. Assessment of bone length, rotation, and congruency of the distal and proximal radioulnar joints of both the bones of the forearm using intraoperative and perioperative plain radiography is required. Radical debridement and periosteum-damaged bone fragments are removed because of bone shortening; so that, chances of nonunion can be low [25].

Author’s surgical tip: As mentioned above, due to the delay in transferring patients to the hospital and preparing for surgery, debridement and arterial anastomosis after bone fixation should be completed within 2 hours. The bone fixation procedure should be simplified to reduce the duration of ischemia while providing sufficient fixation power for stable artery-to-artery anastomosis. The two-stage bone fixation technique was performed in two steps: (1) arterial anastomosis after bone fixation using a small plate by adding an external fixator; (2) then after 4 to 6 weeks, removing the external fixator with change of a long plate instead of a short plate. This method allowed for initial bone fixation within 30 minutes. During the first stage, we decided which bone to fix first, depending on the fracture severity in the radius and ulna. The length of the plate used during surgery was determined based on the length of the exposed bone after shortening. A long plate is useful for strengthening the fixation power for a better bone union. However, the amputated site should be dissected further, which consumes more operative time and causes more tissue injury to the amputated part. The crushed or fractured bone was sawed vertically and a plate with four to six holes was fixed. Subsequently, the radius, ulna, and connecting arteries were serially fixed to ensure recovery of blood circulation. After replantation, external fixation was performed to ensure a strict bone fixation. The second operation is usually performed after 4 to 6 weeks. The external fixator was removed and replaced with a long plate, depending on the condition, or the previous plate was left as it was. In the case of bone defects, a bone graft was performed during the second operation. Based on our experience, using a short plate during the initial surgery shortened the fixation time and enabled a stable anastomosis. Even if this short plate cannot be replaced with a longer one, there is no problem in achieving bone union with good fixation power. This method can achieve revascularization within one hour after the induction of anesthesia (Fig. 1).

The survival of the replanted arm depends on vessel anastomosis and maintenance of circulation. A technique involving vein repair can avoid venous stasis. In addition, a bloodless field should be created for an easier operation. However, in crushing or avulsion amputation, it is better to first connect the artery to find a suitable vein that functions well. At least one major artery should be repaired and connected to the maximum possible number of veins to reduce bleeding after release of the clamp. The comitant vein transfers a large amount of blood and should be restored as much as possible.

Author’s surgical tip: There are two arterial reconstruction approaches; direct anastomosis and saphenous vein graft. We preferred direct anastomosis because of its shorter procedural time. A direct anastomosis usually connects the radial and ulnar arteries. In contrast, our researchers selected an approach wherein anastomosis of the radial and ulnar arteries was performed depending on the status of the vessel injuries. When these two arteries are cross-connected, the duration of the bone-shortening procedure can be further shortened.

Because the upper extremity does not require a lengthening procedure to match the length of both arms, proper bone shortening is the best way for artery anastomosis to reduce the ischemic time. After the arteries are connected and the blood circulation is recovered, vein repair is performed. Commitment venae flowing parallel to the artery should be connected as well as superficial veins in the skin, which can be injured by contamination or hemolysis. Therefore, every possible vein should be reconnected.

The tendon should be repaired during the initial surgery. As bone shortening is usually performed, primary tendon repair becomes easier. If possible, both the muscle belly and the epimysial repair should be sutured. In avulsion amputation, rupture frequently occurs at the musculotendinous junction. Even in this case, connecting the amputated tendon end to the proximal part of the muscle belly resulted in good functional outcomes. If there is a large defect, tendon transfer, tendon graft, or free muscle flap can be considered in the first or second stage.

Author’s surgical tip: As the muscle of the amputated limb may be necrotic and increase the risk of infection, we decided to remove the muscle as much as possible. The proximal muscle was used to cover the vessel-connected area to prevent damage. In addition, we chose the proximal muscle in good condition to connect the tendon of the amputated part with the flexor and extensor. We performed tenorrhaphy of the 2nd through 5th finger flexors together and tenorrhaphy of the thumb separately. The entire extensor is connected to the muscle once.

It is preferable to perform neurorrhaphy of the major nerves during the primary repair without a nerve graft. Bone shortening was performed to avoid nerve graft. If primary repair is not possible, the nerve should be tagged in the appropriate area to ease operation of the nerve graft.