Replantation in Emergency Medicine

In the past 200 years, successful replantation of amputated digits has gradually moved from fantasy to reality. William Balfour performed the first successful fingertip reattachment in 1814; Thomas Hunter is credited with the first thumb replantation performed in the following year.

Little progress was made until the pioneering work of William Steward Halstead and Alexis Carrel, who performed replantation experiments with dog limbs in the 1880s. Dr Carrel won the Nobel Prize in 1912 for his work on vascular anastomoses and for pioneering kidney transplantation.

In 1962, Ronald A. Malt performed the first successful replantation of an entire limb in a 12-year-old boy whose arm had been severed in a train accident. With the development of the operating microscope by Julius Jacobson and Ernesto Suarez in the early 1960s, replantation became easier, and its use began to spread throughout the Western world.

With the advent of microvascular reanastomosis, digit replantation became tenable. In 1965, Shigeo Kmatsu and Susumu Tamai were the first to perform such a procedure. Since then, medicine has advanced to include the successful replantation of a child’s completely amputated ear as well as replantation of multiple digits and hands. ^{[1, 2]}

Modern replantation is now available in most large hospitals, and favorable functionality and cosmetic appearance is increasingly common. ^[3]

Amputation replantation is the reattachment of a completely severed part. This is distinguished from incomplete nonviable amputations, which require revascularization. Revascularization is the reconstruction of the blood supply of an incompletely amputated part. In general, revascularization usually provides better functional results than replantation itself.

However, viability alone is an inadequate measure of success. The main predictive factors include the following ^[4]

• Injury mechanism (crushing and avulsion have the worst prognosis)
• Platelet count
• Smoking after the operation
• Preservation method of the amputated part
• Use of vein grafting

Amputations of the distal phalanx and the thumb, male gender, and ischemia time greater than 12 hours along with presence of diabetes seem to portend a somewhat worse prognosis. Age and history of alcohol use are less significant factors toward the success of replantation. ^[5]

The 6 mechanisms of amputation injury are the following:

• Sharp cut, as from a knife or meat slicer
• Dull cut, as from a saw or dull edge (eg, fan blade)
• Cut with a narrow segment of crush injury, as from a punch press
• Cut and avulsion, as from a machine that causes partial amputation and subsequent reflexive withdrawal of the hand that completes the amputation
• Avulsion, as from a finger or a hand caught in an anchor rope or horse reins
• Crush avulsion, as from a machine (eg, rollers) that crushes the limb then pulls the digits off

A study of United States inpatient data from 2001, 2003, and 2007 found that 9407 patients were treated for upper extremity amputation and 1361 of those underwent replantation (14.5%). ^[6]  Although finger amputation injuries have increased over time, the rate of replantation has declined. In 2001, 2004, and 2007 combined, only 27% of thumb and 12% of finger traumatic amputations were replanted. ^[7]  

Mean age of patients undergoing replantation was 36 years (range, 0-86 y), compared with 44 years (range, 0-104 y) in patients not undergoing replantation. In the United States, 87% of patients with amputation who underwent replantation were male. ^[6]

African-American patients are less likely to undergo a replantation procedure after experiencing a finger/thumb amputation injury, likely due to disparities in surgical settings associated with system-level differences in access to care. ^[7]  Longer emergency department wait times are associated with lower odds of replantation, and being a minority and having no insurance are associated with longer ED wait times. ^[8]  

Hospital charges and length of inpatient stay were significantly higher ($43,000, 5.8 days) for patients with replantations versus those without replantations ($28,000, 3.5 days). Patients treated at teaching facilities were more likely to undergo replantation than those at a nonteaching facility (19% vs 7%). Large hospitals and urban hospitals were more likely to perform replantation. Self-pay, Medicare, and Medicaid patients all had lower replantation rates than patients with private insurance or workers’ compensation. ^[6]  

Despite recent microsurgical advancements, evidence suggests that in contrast to other developed countries, replantation success rates in the United States have fallen to approximately 60%. ^[7]   This may be due to a significant decline in digital replantations being performed, despite a relatively stable incidence of amputations. Compared with 930 replantations in 2001, only 445 were performed in 2011, more than a 50 percent decrease (p < 0.001). In all years, the majority of hospitals performing replantation performed only one (49.3 to 64.1 percent) each year, with a small minority (2.2 to 8.1 percent) performing more than 10 per year. ^[9]   

The results of a retrospecitive study of 631 digit replantation attempts from five U.S. states found the hospital annual replantation volume increased the odds of success (OR=1.06, CI: 1.02–1.10). An annual hospital volume of 3 replants was needed to achieve a success rate of 70%. ^[10]  

Replantation survival rates of 80-90% have been described in selected reports, but outcome is related not only to the success of the microvascular anastomosis, but to the adequacy of bone, tendon, and nerve repairs. Sensory recovery following digit replantation occurred in 70% of patients, as defined by 2-point discrimination of less than 15 mm. Sensory recovery is better following replantation with sharp-cut mechanism rather than avulsion. Overall, 61% of thumbs and 54% of fingers recovered useful sensory function by 2-point discrimination. ^[6]

Arterial insufficiency is one of the most common causes for replantation failure. Other causes include venous congestion and thrombosis. 

Function may be limited after replantation. Multivariate analysis of factors that favor functional recovery after finger replantation or revascularization showed better recovery for patients younger than 40 years compared with older patients. Injuries caused by a sharp mechanism have a better prognosis than those caused by a crush mechanism; injuries caused by a crush mechanism have a better prognosis than those caused by avulsion; and injuries at the middle phalangeal level have a better prognosis than those at the proximal level. A meta-analysis showed that smoking, diabetes, and avulsion or crush injury are poor prognostic factors in replantation of amputated digits.  ^[5]

Cold intolerance of the replanted limb is a universal problem. ^[11] Similarly, cold-induced vasospasm occurs in essentially all patients. Sensitivity to light touch and 2-point discrimination frequently is impaired, while limitations in the flexion of joints distal to the replantation vary. Cosmetic deformity may occur.  Average finger flexion for reimplanted digits has been shown to be 129°. Replantation in zones 1 and 5 fared better than those in zones 2 through 4. As with survival and nerve function, avulsion mechanisms had poorer outcomes. ^[6]

Complications following reimplantation include infection and osteomyelitis. Myonecrosis leading to rhabdomyolysis and renal insufficiency may occur if significant muscle mass that was transiently ischemic is replanted. These occur with forearm or lower leg replantations but not with finger replantations.