This is a single-centered prospective study that included data from patients (group N) who received emergency phalanges replantation due to digit severed lesions from 1 August to 30 September 2021 at the Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine. Data from patients who received emergency phalanges replantation from 1 June to 31 July 2021 were recorded as a control group (group C).

Patients who met the following status were included: (1) single-planed open amputated digit lesion without previous phalangeal replantation history and with one or more digits involved; (2) either complete or incomplete amputation that caused complete or incomplete loss of blood supply of the distal part; (3) digit replantation accepted by the patient or the patient's guardian; (4) combined with other injuries, but the rest of the injuries in both upper extremities did not require emergency amputation surgery.

Patients who met the following status were excluded: (1) amputated digits were caused by hot crush violence or with degloving injury; (2) intolerance of surgery due to systematic diseases, such as severe cardiovascular diseases, epilepsy, intoxication, and drug allergy; (3) digit replantation was rejected by the patients.

The study was in accordance with the 1975 Declaration of Helsinki. Ethical approval of the study was obtained from the Institutional Ethics Committee of Shanghai Sixth People's Hospital [2021-KY-113(K.)] The patients and/or their bailors were informed that data from the case would be submitted for publication and their consent was obtained.

Patients with digit amputation injuries first received basic COVID-19 screening according to their history of epidemiology and axillary temperature at emergency previewing counter. Patients were sorted as preclusion-required patients after first screening (PRFS) and were guided to the fever clinic (FC) through a restricted lane for further COVID-19 virus nucleic acid test, blood routine examination, and pulmonary computed tomography (CT) in order to preclude COVID-19 if they met one of these situations: (1) an axillary temperature above 37.3°C, (2) a sojourn history in moderate- or high-risk regions for COVID-19 pandemic countrywide or abroad within 14 days, (3) close contact with COVID-19 patients, and (4) work history at ports. Otherwise, patients negative for COVID-19 after first screening (NFS) were guided toward the emergency room for traumatic orthopedics and received surgery- and anesthesia-related examinations as well as COVID-19 virus nucleic acid test, blood routine examination, and pulmonary CT. Diagnostic criteria of COVID-19, including history of epidemiology, and laboratory and radiological examinations, were in accordance with the National COVID-19 diagnosis and treatment guidelines (Interim version 8) (13). All patients were required for routine follow-up at 1, 2, 4, 6, 8, and 12 weeks postoperatively, and clinical outcomes were evaluated at each follow-up.

Before 1 August 2021, NFS patients with negative results of blood routine examination and pulmonary CT, and PRFS patients with negative results of COVID-19 virus nucleic acid test, blood routine examination, and pulmonary CT could receive phalanges replantation surgery under brachial plexus anesthesia in a negative-pressure operating room once they finished surgery- and anesthesia-related examinations and were then transported to special units for amputation injury postoperatively. NFS patients with positive results of either blood routine examination or pulmonary CT and PRFS patients with at least one positive result of COVID-19 virus nucleic acid test, blood routine examination, and pulmonary CT were sorted as suspect patients after first screening (SFS), and further assessment by the epidemiology prevention and control expert group was required to distinguish assessed negative patients (ANP) and COVID-19 suspected/diagnosed patients (SDP). ANP could receive replantation surgery under regular protocols in a negative-pressure operating room after preoperative examinations and were then transported to special units for amputation injury postoperatively. Twenty-four hours after the operation, another COVID-19 virus nucleic acid test was performed, and patients with positive result were transferred to specified hospitals for COVID-19 patients. SDPs were guided to the negative-pressure operating room for replantation surgery through a restricted lane after finishing preoperative examinations, and thorough sterilization and a 90-min lockdown of the operating room were acquired postoperatively. SDPs were temporarily transported to isolated wards and were then transferred to specified hospitals for COVID-19 patients postoperatively (Figure 1).

Since 1 August 2021, results of COVID-19 virus nucleic acid test within 72 h should be compulsorily obtained before emergency replantation surgery at our hospital, namely, COVID-19 virus nucleic acid testing normalization. NFS patients could only receive operation after obtaining negative results of COVID-19 virus nucleic acid test, blood routine examination, and pulmonary CT in the negative-pressure operating room. NFS or PRFS patients with at least one positive result require further assessment by the epidemiology prevention and control expert group before arranging for the operation. Except for SDPs, additional COVID-19 virus nucleic acid test, blood routine examination, and pulmonary CT were arranged for patients with fever due to unknown cause. This period is the so-called COVID-19 virus nucleic acid testing normalization.

Emergency digit replantation was performed by the same surgical team under brachial plexus anesthesia. Main structures of each amputated digit, including bilateral neurovascular bundles, tendons, adequate veins, and bone, were cautiously reconstructed. Three veins and volar bilateral arteries were anastomosed in routine. Standard second-level protection, same as protection of usual hand surgery, was applied for surgical team when performing operation for non-SDPs. Standard third-level protection, with additional protective suit under normal surgical gown, two extra pairs of sterile gloves, and a face shield, was applied for surgical team when performing operating on SDPs (13, 14) (Figure 2). Postoperative care equaled to the routine managements in a published article (15).

Demographic data, history of epidemiology, physical examination results, experimental results, treatment, and prognosis data were collected through electronic medical record system. These data included gender, age, patients epidemiological risk degree, mechanisms of injury, number of affected digits, names of affected digits, lacerated and repaired structures of affected digits, time from injury to surgery (TIS), time from emergency visit to surgery (TVS), operation time (OT), hospitalization time (HT), complications, and clinical outcomes. Hand injury severity scoring (HISS) was applied for the assessment and grading of the severity of the injury, which was performed by assigning scores for the lesions in the aspect of skin, nail, nerve, intrinsic muscle and tendon, bone, and ligament of the hand and calculating the weighing sum according to the status of importance of the amputated digit (16). Disability of arm-shoulder-hand (DASH) questionnaire was applied both preoperatively and 3 months after the operation to evaluate the improvement of the affected upper extremities, which includes two major parts regarding the ability of upper extremity activities (Part A) and severity of symptoms (Part B) (17). Clinical grading was performed by two separate researchers, and a third evaluation was done if the first two grading varied.

Grading of HISS for severity of the injury: minor (0–20 points), moderate (21–50 points), severe (51–100 points), and major (above 100 points).

DASH score was calculated as follows:DASH=Asum+Bsum−301.20

We introduce a novel parameter, the improved rate of DASH score (impDASH), to compare the outcomes of emergency digit replantation before (group C) and after (group N) COVID-19 virus nucleic acid testing normalization, calculated as follows:impDASH=DASHpreoperative−DASHthree−monthDASHpreoperative×100%

Statistical analysis was performed using GraphPad Prism 5 (GraphPad software, CA, United States). Normal distribution was checked statistically. Descriptive statistics were expressed as mean ± standard deviation (`x ± s) for continuous numerical variables and as number and percentage for categorical variables. Unpaired two-group t-test was applied to compare age, time related with management and follow-up, numbers of injured structures, and objective outcomes (the DASH score). Chi-square t-test was applied to compare characteristics of injuries of the two groups. P value < 0.05 was considered a significant difference.

Fifty-eight patients who received emergency digit replantation were included in group C from 1 June to 31 July 2021. None of them were assessed as SDPs, and two patients (3.4%) were sorted as PRFS or SFS patients. Mean age of the patients in group C was 40.4 ± 13.5 years (4–72 years). Mean TVS was 1.77 ± 0.67 h. Eighty-seven severed digits were replanted, with 81 survival fingers (93.1%), average HISS of 107.8 ± 79.0 points, and average preoperative DASH score of 53.8 ± 17.6 points. The severity of the injury was graded as 19 moderate, 17 severe, and 22 major in group C according to HISS of the patients.

Fifty-four patients who received emergency digit replantation were included in group N from 1 August to 30 September 2021. Five patients were evaluated as PRFS patients, and another patient (1.9%) was tested as COVID-19 suspected patient; they all were assessed as an ANP by the epidemiology prevention and control expert group for emergency replantation surgery. Mean age of the patients in group N was 46.4 ± 16.3 years (2–81 years). Mean TVS was 3.83 ± 0.94 h. Seventy-four severed digits were replanted, with 72 survival fingers (97.3%), average HISS 89.4 ± 51.6 points, and average preoperative DASH score 54.3 ± 16.7 points (Table 1). Severity of the injury was graded as 15 moderate, 18 severe, and 20 major in group N according to HISS of the patients.

It is obvious that results of COVID-19 virus nucleic acid test from only 3.4% patients in group C were required before receiving emergency digit replantation, while results of COVID-19 virus nucleic acid test from all patients were required in group N.

Although patients in group N had an older age (46.4 ± 16.3 years) compared with patients in group C (40.4 ± 13.5 years), there remained no significant difference (95% CI: −1.1 to 12.6, P = 0.100). Mean TVS was significantly prolonged in group N (3.83 ± 0.94 h) compared with that of group C (1.77 ± 0.67 h) (95% CI: 1.8 to 2.4, P < 0.05). Before COVID-19 virus nucleic acid testing normalization, a total of six fingers did not survive (ring and litter finger in a patient received 2–5 left fingers replantation HISS 217, and 1–4 necrosis received 1–5 left fingers replantation, HISS 164), while two fingers after the policy (left thumb received left thumb replantation HISS 42, and left index finger received left index finger replantation HISS 36). There was no significant difference (P = 0.222) in survival rate before and after the policy.

Lower HISS was also observed in group N (89.4 ± 51.6 points) compared with that of group C (107.8 ± 79.0 points), but there was still no significant difference (95% CI: −7.0 to 43.9, P = 0.154). Although DASH scores of patients in both groups were significantly improved (P < 0.05), no significant difference was observed in the aspects of preoperative DASH score (P = 0.890), DASH score 3 months after operation (P = 0.850), impDASH (95% CI: −4.0 to 7.6, P = 0.538), and rate of complication (P = 0.344). These data suggested that the two groups shared similar severity of injury and clinical outcomes.

DASH scores of replanted digits with different levels of severity were significantly improved in both groups (Table 2 and Table 3). Although COVID-19 virus nucleic acid testing normalization significantly prolonged TVS (3.83 ± 0.94 h in group N, 1.77 ± 0.67 h in group C, 95% CI: −2.4 to −1.8, P < 0.05), no significant difference of impDASH was observed in patients with same level of severity in both groups (Table 4).

After COVID-19 virus nucleic acid testing normalization, a 7-year-old girl visited the orthopedic emergency room 2 h after injury due to incomplete left index finger avulsion. Physical examination reported that the index finger was lacerated at the level of proximal metaphysis of the proximal phalangeal bone with only intact flexor digitorum profundus tendon. HISS scored 38 points and preoperative DASH scored 47.5 according to the physical evaluation (Figures 3A,B). After finishing the preoperative examinations as well as COVID-19 virus nucleic acid test, emergency digit replantation was performed under brachial plexus anesthesia 6 h after injury. Proper palmar arteries of her left index finger were damaged and showed severe spasm lesion; hence, anastomosis was performed between adjacent dorsal digit arteries and distal ends of the proper palmar arteries of the left index finger (Figures 3C–F). The affected finger successfully survived with an impDASH of 82.5% and a DASH score of 8.3 points 3 months after operation (Figures 3G–I).