This study aims to describe the application of a modified St. Thomas' solution in patients with severe limb injuries.

Four patients who sustained a high-energy trauma and underwent complete upper limb amputation were pretreated with a modified St. Thomas' solution before upper limb replantation. After the perfusion solution stopped flowing from the blood vessel, the amputated upper limb amputation was replanted. The patients were instructed to perform functional rehabilitation training after the operation. All 4 patients were followed up for 5 years. All the severed upper limbs survived. Routine re-examination after the operation showed that the function of the affected limb was restored. All the patients were satisfied with the sensory and functional recovery of the affected limb.

The modified St. Thomas' solution can effectively improve the success rate of limb salvage surgery and the recovery of limb function in patients with a severe limb injury.

Severe limb injuries often include fracture, blood vessel, muscle tissue and nerve injuries[1]. Due to the advent of trauma orthopedics and microsurgery, limb, vascular and nerve reconstruction has become increasingly popular; however, there is no clinical research investigating ischemia-reperfusion injuries (IRIs) in skeletal muscles[1]. It is generally believed that the ischemic resistance time of skeletal muscle is much longer than that of other organs[2]. For example, during limb surgery, tourniquets can only be used for 1.5-2 h to avoid causing irreversible damage to the skeletal muscle[2]. However, the treatment time of severe limb injury is generally 6-8 h. Although there are some physical and chemical methods to prevent a skeletal muscle IRI in patients with severe limb injuries, the treatment effect is far from satisfactory[1,2]. To address this problem, this paper explores the use of a modified St. Thomas' Solution in patients with severe limb injuries.

The diagnoses were hemorrhagic shock and a severed right upper arm.

After emergency anti-shock treatment, the patient's vital signs gradually stabilized. In the emergency department, debridement of the right upper arm, internal fixation of the humeral fracture, and exploration and repair of blood vessels, nerves and muscles were performed under general anesthesia (Figure 1E-G). The specific operation method was the same as above.

Within 1 wk after the operation, the degree of swelling of the affected limb was mild, and the patient’s internal environment was stable 2 wk after the operation. The temperature of the wrist was restored, wrist pain was alleviated at 3 mo after the operation, and finger temperature and touch were restored at 6 months (Figure 1H). One year after the operation, the affected limb could be used to drink water, dial a mobile phone and write with a pen. The right elbow could be straightened to 10°, flexed to 90°, pronated to 70° and supinated to 60° at the follow-up visit 5 years after the operation. According to the elbow score of the American Special Surgery Hospital, the function was good; the right wrist joint could be straightened to 75° and flexed to 70°. The Cooney wrist joint score was 80 points, and the function was good; right hand function loss was 30% according to the hand function evaluation scheme (percentage of motor loss) (Figure 1I-P).

In recent years, scholars have gradually reached a consensus that the protection of muscle tissue is not only the key to salvaging limb function but also the key to the patient’s ability to return to life activities and work[1,2]. Therefore, the correct selection of limb protection measures is necessary for microsurgery and trauma orthopedics.

The mechanism of skeletal muscle IRIs is complex and has not been fully clarified. The main injury mechanisms include oxygen free radical injury, aggregation of inflammatory factors and neutrophils, calcium overload, imbalance between nitric oxide and vascular endothelin, apoptosis and no reflow[3]. Regarding the above main pathogenesis, researchers have conducted in-depth explorations of the protective effects of skeletal muscle IRIs. At present, the main treatment methods include simple low-temperature cold preservation, hyperbaric oxygen preservation, ischemic preconditioning, postreperfusion adaptation, temporary ectopic foster replantation of severed limbs and perfusion technology[4,5]. Among them, perfusion technology has attracted the attention of an increasing number of researchers and clinicians because of its feasible clinical application and improvements.

Many perfusion fluids that have been developed in recent years, such as EC solution, UW solution, HTK solution and CEL solution, have been used in the clinical setting and have achieved good results. Bastiaanse et al[6] observed the microcirculation through a living microscope and found that after replantation of testicular muscle that was preserved in HTK solution, the microcirculation was well refluxed, edema was significantly reduced, the protective effect was significantly better than that in the normal saline group, and the longest preservation time was up to 24 h[6]. Wagh et al[7] divided rats into a hypothermic control group, a hypothermic saline perfusion group and a hypothermic modified UW solution perfusion group. After 24 h of ischemia and 24 h of reperfusion, the vitality of the gastrocnemius myocutaneous flap in the three groups was 26%, 28% and 33%, respectively. It was considered that perfusion of the modified hypothermic UW solution could effectively reduce low temperature injuries to the severed limb[7]. Kingston et al[8] found through the rat hindlimb ischemia-reperfusion model, that taurine can protect the tetanic contractility of muscle[8]. Wang et al[9] created a rat model of hindlimb IRI and found that the serum CPK, AST and LDH levels in the UW solution group were significantly lower than those in the control group after 2 h of reperfusion, and there was no significant difference between 4 h and 6 h of reperfusion. MDA, SOD and ATPase levels in skeletal muscle were significantly different from those in the control group within 4 h after reperfusion, and there was no significant difference at 6 h[9]. St. Thomas' solution is a classic myocardial protective solution. Several studies have shown that St. Thomas' solution can reduce myocardial IRI by scavenging oxygen free radicals, inhibiting inflammation and reducing apoptosis to protect the myocardium[10]. Because St. Thomas' solution can protect the myocardium, our research group adjusted the content of K⁺ to adapt to the internal environment of the skeletal muscle cells and then explored the role of the improved St. Thomas' solution in severe limb injury treatment.

We found that preperfusion with modified St. Thomas' solution can reduce swelling of the residual limb in the early stage of perfusion, stabilize the environmental changes in the perioperative period, and effectively improve the success rate of limb salvage surgery and the recovery of affected limb function in patients with a severe limb injury. The 4 patients in the study were sent to the hospital for surgical treatment within 8 h after injury, which is a prerequisite for successful treatment. Age is also very important factor. The patients were young and middle-aged (range from 26 to 42 years). Moreover, there was a significant difference between replantation of the large limb and replantation of the finger. Skeletal muscle IRIs should be taken into consideration. The more skeletal muscle the severed tissue carries, the greater the risk of replantation. The upper arm of 2 patients was severed and the lower part of the upper arm of 2 patients was severed. The former is more likely to recover function than the latter.

There are also some deficiencies in this study. Due to the low incidence of severe limb injuries, prolonged follow-up period and follow-up loss, the sample size was small. In the future, we will continue to identify patients and increase the sample size.

Our study indicated the pretreatment with a modified St. Thomas' solution was an effective and reliable option for the reconstruction of limb function in patients with a severe limb injury. Perfusion technology provides a feasible clinical application and improvements. It reduces the production of toxic substances and metabolites due to skeletal muscle IRIs. This onestage management has been proved effectively and safely in severe limb injury.