Abstract
Purpose: Understanding the variables that influence success in digital replant surgery is essential to guide clinical decision-making and to counsel patients. The purpose of this study was to determine the replant success rate and identify predictors of success at our tertiary care centre. Methods: This was a single centre, retrospective cohort study of consecutive patients who underwent digital replantation from January 2000 to September 2018. Adult patients with flexor zone I to III amputations were included. Patient demographics, comorbidities, injury pattern, operative data, and post-operative care were reviewed. The primary outcome was survival of the replanted digit at discharge. Results: A total of 146 patients met inclusion criteria. Of these, 100 had single-digit replants and 46 underwent multi-digit replants for a total of 220 digits. The success rate was 71%. Predictors of success included sharp mechanism of injury (P < .01), incomplete amputation (P < .01), amputation proximal to zone I flexor level (P = .02), post-operative acetylsalicylic acid use (P < .01), absence of leech use (P = .05), and absence of operative re-exploration (P < .01). Daytime replants had similar outcome compared to nighttime replants despite having increased ischemia time (7.9 ± 3.9 hours vs 6.8 ± 2.6 hours, P = .02). However, daytime operative time (7.8 ± 3.7 hours) was significantly shorter than nighttime replant time (9.6 ± 5.9 hours, P = .01). Conclusion: Sharp amputation, intact venous drainage, proximal amputation, and acetylsalicylic acid use were associated with replant survival and are factors to consider when managing patients for digital replantation. Leech therapy and operative re-exploration were associated with poor outcome. Nighttime replants required significantly longer operative time than daytime replants despite similar survival outcome.
Keywords: digital amputation, digital replant, daytime surgery, nighttime surgery
Abstract
Objectif: Il est essentiel de comprendre les variables qui influent sur la réussite de la réimplantation digitale par voie chirurgicale pour orienter les décisions et conseiller les patients. La présente étude visait à déterminer le taux de réussite des réimplantations et à déterminer les prédicteurs de réussite au centre de soins tertiaires des chercheurs. Méthodologie: Cette étude de cohorte monocentrique et rétrospective portait sur des patients consécutifs qui avaient subi une réimplantation chirurgicale entre janvier 2000 et septembre 2018. Les patients adultes ayant subi des amputations des zones I à III des fléchisseurs ont été retenus. Les chercheurs ont évalué les caractéristiques démographiques des patients, leurs maladies associées, leur type de blessures, les données opératoires et leurs soins postopératoires. La survie du doigt réimplanté au congé était le résultat primaire. Résultats: Au total, 146 patients ont respecté les critères d’inclusion. De ce nombre, 100 avaient fait réimplanter un seul doigt et 46, plusieurs doigts, pour un total de 220 doigts. Le taux de réussite s’élevait à 71%. Les prédicteurs de réussite incluaient un mécanisme franc de blessure (p<0,01), une amputation incomplète (p<0,01), une amputation proximale au fléchisseur de la zone I (p=0,02), la prise d’acide acétylsalicylique après l’opération (p<0,01), la non-utilisation de sangsues (p=0,05) et l’absence de réexploration opératoire (p<0,01). Les réimplantations effectuées le jour donnaient des résultats semblables à celles qui étaient effectuées la nuit, malgré une durée d’ischémie plus longue (7,9±3,9 h par rapport à 6,8±2,6 h, p=0,02). Cependant, les opérations exécutées le jour (7,8±3,7 h) était beaucoup plus courtes que celles effectuées la nuit (9,6±5,9 h, p=0,01). Conclusion: Une amputation franche, un drainage veineux intact, une amputation proximale et la prise d’acide acétylsalicylique étaient liés à la survie de la réimplantation et représentent des facteurs à considérer dans la prise en charge des patients qui doivent subir une réimplantation digitale. La thérapie par les sangsues et la réexploration opératoire étaient associées à un mauvais pronostic clinique. Les réimplantations opératoires effectuées la nuit étaient beaucoup plus longues que celles effectuées le jour, malgré un taux de survie semblable.
Introduction
Digital replantation is a technically challenging and demanding procedure due to varying mechanisms of injury, ischemia time, and the stamina required for these long surgeries. A recent meta-analysis shows success rates can vary between 53% and 96%. 1 Experienced microsurgeons are crucial and may influence outcome. 2 Both Brown et al and Mahmoudi et al have demonstrated that hospitals with higher annual volume have greater replant success rates. 3,4 A well-integrated replant team is preferred given the time and resources required for multiple digits or complicated single-digit replant procedures. 5
In addition to surgeon factors, several perioperative factors are predictors of outcome. Zhu et al demonstrated that increased age, non-sharp injury, heavy smoking, and prolonged ischemia time (>12 hours) are associated with failure. 6 However, recent systematic reviews suggest that ischemia time is not a significant predictor of survival. 1,7 A comparative retrospective cohort study by Cavadas et al found comparable outcomes between immediate replantation and delayed replantation. The authors suggest that if the replant part is appropriately stored with cold ischemia time limited to <24 hours, delaying a procedure from nighttime to daytime is not associated with worse outcome. 8
The purpose of our study was to compare our centre’s digital replantation success rate with other regional centres and to identify factors that predict replant survival in our patient population.
Materials and Methods
Following institutional review board approval (identification number: H18-02655), a retrospective chart review was performed on all patients undergoing replantation between January 1, 2000, and September 31, 2018, at our tertiary care centre. Patients older than 18 years who underwent digital replantation at the level of flexor zones I to III were eligible for inclusion. Patients with flexor zone IV or more proximal level amputations were excluded.
We collected data on patient demographics (age, sex), comorbidities (type II diabetes, coronary artery disease, cerebral vascular disease, peripheral vascular disease, obesity, smoking), injury pattern (digit number, multi-digit injury, multi-digit replant, mechanism, partial amputation, flexor level, ischemia time), operative data (day vs night surgery, number of surgeons, hand vs non-hand surgeon, American Society of Anesthesia Classification [ASA] level, heterotopic replant, number of arterial anastomosis, number of venous anastomosis, vein graft, intraoperative heparin), and post-operative care (post-operative infusional continuous regional anesthesia [PICRA], anticoagulation, leech therapy, operating room [OR] re-exploration). Partial amputations were defined as amputations involving both digital arteries but dorsal skin and/or other structures remain intact. Hand surgeons were defined as plastic surgeons with additional fellowship training in hand surgery and/or with a predominant hand practice. Replants were categorized as overnight procedures when the majority of the surgery occurred between 7 pm and 7 am. The final outcome of interest was survival of the digit at the time of discharge. This was defined as the presence of capillary refill in the fingertip.
Institutional Replant Protocol
Vancouver General Hospital is the level I, tertiary trauma center for the Vancouver Coastal Health regional health authority. It serves 1.25 million residents in a geographic area of 58 560 square kilometres. Patients deemed as possible candidates for replantation at peripheral hospital sites are transferred urgently through the patient transfer network. Vancouver General Hospital plastic surgery team provides round-the-clock coverage for emergent plastic surgery referrals, which includes all local replants. However, there is no dedicated replant team and the plastic staff surgeons on call have variable fellowship training and practices (eg, hand, breast, craniofacial). There is no official local replant criteria, the decision is made with each case after discussion with the patient. Once the decision for replant is made, patients are booked into the OR as emergent E1 cases. No delayed overnight fridge ischemia protocol was employed. Operating microscopes are routinely used for microsurgical repair of vessels and nerves. Kirschner wires are the most common method for bony fixation. Post-operatively, patients are monitored on the plastic surgery unit with hourly replant checks by nurses experienced with flap monitoring. Post-operative anticoagulation with daily 81 mg oral ASA and low-molecular-weight heparin is increasingly employed with the routine use of division-approved preprinted order form. Patients usually remain in hospital for at least 5 days for monitoring of replant.
Statistical Analysis
A binary logistic regression model was employed to determine predictors of replant success. The forward conditional method was used to enter all variables and those deemed statistically significant were used in the final model. Subgroup analysis between daytime and nighttime surgery was performed. Variables that were significant on univariate analysis and variables deemed to affect digital survival a priori were included in the multivariate analysis using a covariance model. P value <.05 was considered statistically significant. Data analyses were conducted with IBM SPSS Statistics Version 24 software (SPSS).
Results
Over the 19-year study period, 146 patients fit the inclusion criteria. Of these patients, 132 (90.4%) were male, and the average age was 41.1 ± 14.6. One hundred (68.5%) patients had single replants and 46 (31.5%) underwent multi-digit replants. All replants were performed with ischemia time less than 17 hours, and the average was 7.1 hours (Tables 1 -4). In total, 220 digits were replanted. The overall success rate was 71%. Success rates divided by replant type were 63% in complete amputation cases, 90% in partial amputation cases, 74% in multi-digit replant cases, and 68% in single-digit replant cases (Table 5). The replant success rate remained stable over the years averaging 8 cases per year. The replant volume peaked in 2008 with a total of 12 replant cases that year and gradually declined yearly to 7 cases in 2018 (Figure 1).
Table 1.
Patient Demographics.
| Variable | Patients N = 146 |
|---|---|
| Age, mean ± SD | 41.1 ± 14.6 |
| Male gender, no. (%) | 132 (90.4%) |
| Comorbidities, no. (%) | |
| Type II diabetes | 17 (7.7%) |
| Coronary artery disease | 13 (5.9%) |
| Cerebrovascular disease | 0 (0%) |
| Peripheral vascular disease | 0 (0%) |
| Obesity (BMI > 30) | 10 (4.5%) |
| Smoking | 38 (26.0%) |
| Variable | Digits n = 220 |
| Injury pattern, no. (%) | |
| Finger | |
| Thumb | 65 (29.5%) |
| Index | 28 (12.7%) |
| Long | 60 (27.3%) |
| Ring | 47 (21.4%) |
| Small | 20 (9.1%) |
| Sharp | 25 (11.4%) |
| Saw | 153 (69.5%) |
| Avulsion | 27 (12.3%) |
| Crush | 15 (6.8%) |
| Multi-digit injury | 157 (71.4%) |
| Multi-level injury | 4 (1.8%) |
| Multi-digit replant | 120 (54.5%) |
| Complete amputation | 152 (69.1%) |
| Flexor level | |
| Zone I | 34 (15.5%) |
| Zone II | 170 (77.3%) |
| Zone III | 16 (7.3%) |
| Operative data, no. (%) | |
| Nighttime procedure | 161 (73.2%) |
| Surgeon number | |
| 1 | 122 (55.5%) |
| 2 | 61 (27.7%) |
| 3 | 30 (13.6%) |
| 4 | 7 (3.2%) |
| Hand surgeon | 173 (78.6%) |
| ASA class | |
| 1 | 89 (40.5%) |
| 2 | 112 (50.9%) |
| 3 | 17 (7.7%) |
| 4 | 2 (0.9%) |
| Surgery time, mean ± SD | 9.09 ± 5.41 h |
| Surgery time per digit, mean ± SD | 4.83 ± 2.11 h |
| Ischemia time, mean ± SD | 7.07 ± 3.01 h |
| Heterotopic replant | 11 (5.0%) |
| Arterial anastomosis | |
| 1 | 179 (81.4%) |
| 2 | 41 (18.6%) |
| Venous anastomosis | |
| 0 | 70 (31.8%) |
| 1 | 87 (39.5%) |
| 2 | 52 (23.6%) |
| 3 | 11 (5.0%) |
| Vein graft | 62 (28.2%) |
| Intraoperative heparin | 68 (30.9%) |
| Post-operative care, no. (%) | |
| PICRA | 176 (80.0%) |
| Acetylsalicylic acid | 198 (90.0%) |
| Unfractionated heparin DVTp | 94 (42.7%) |
| LMWH DVTp | 22 (10.0%) |
| Heparin infusion | 48 (21.8%) |
| DOAC | 2 (0.9%) |
| Dextran | 68 (31.1%) |
| Leech | 72 (32.7%) |
| Operative re-exploration | 16 (7.3%) |
Abbreviations: ASA, American Society of Anesthesia Classification; BMI, body mass index; DOAC, direct oral anticoagulation; DVTp, deep vein thrombosis prophylaxis; LMWH, low-molecular-weight heparin; PICRA, post-operative infusional continuous regional analgesia; SD, standard deviation.
Table 2.
Injury Pattern.
| Variable | Digits n = 220 |
|---|---|
| Injury pattern, no. (%) | |
| Finger | |
| Thumb | 65 (29.5%) |
| Index | 28 (12.7%) |
| Long | 60 (27.3%) |
| Ring | 47 (21.4%) |
| Small | 20 (9.1%) |
| Sharp | 25 (11.4%) |
| Saw | 153 (69.5%) |
| Avulsion | 27 (12.3%) |
| Crush | 15 (6.8%) |
| Multi-digit injury | 157 (71.4%) |
| Multi-level injury | 4 (1.8%) |
| Multi-digit replant | 120 (54.5%) |
| Complete amputation | 152 (69.1%) |
| Flexor level | |
| Zone I | 34 (15.5%) |
| Zone II | 170 (77.3%) |
| Zone III | 16 (7.3%) |
Table 3.
Operative Data.
| Variable | Digits n = 220 |
|---|---|
| Operative data, no. (%) | |
| Nighttime procedure | 161 (73.2%) |
| Surgeon number | |
| 1 | 122 (55.5%) |
| 2 | 61 (27.7%) |
| 3 | 30 (13.6%) |
| 4 | 7 (3.2%) |
| Hand surgeon | 173 (78.6%) |
| ASA class | |
| 1 | 89 (40.5%) |
| 2 | 112 (50.9%) |
| 3 | 17 (7.7%) |
| 4 | 2 (0.9%) |
| Surgery time, mean ± SD | 9.09 ±5.41 h |
| Surgery time per digit, mean ± SD | 4.83 ±2.11 h |
| Ischemia time, mean ± SD | 7.07 ± 3.01 h |
| Heterotopic replant | 11 (5.0%) |
| Arterial anastomosis | |
| 1 | 179 (81.4%) |
| 2 | 41 (18.6%) |
| Venous anastomosis | |
| 0 | 70 (31.8%) |
| 1 | 87 (39.5%) |
| 2 | 52 (23.6%) |
| 3 | 11 (5.0%) |
| Vein graft | 62 (28.2%) |
| Intraoperative heparin | 68 (30.9%) |
Abbreviations: ASA, American Society of Anesthesia Classification; SD, standard deviation.
Table 4.
Post-Operative Care.
| Variable | Digits n = 220 |
|---|---|
| Post-operative care, no. (%) | |
| PICRA | 176 (80.0%) |
| Acetylsalicylic acid | 198 (90.0%) |
| Unfractionated heparin DVTp | 94 (42.7%) |
| LMWH DVTp | 22 (10.0%) |
| Heparin infusion | 48 (21.8%) |
| DOAC | 2 (0.9%) |
| Dextran | 68 (31.1%) |
| Leech | 72 (32.7%) |
| Operative re-exploration | 16 (7.3%) |
Abbreviations: DOAC, direct oral anticoagulation; DVTp, deep vein thrombosis prophylaxis; PICRA, post-operative infusional continuous regional analgesia.
Table 5.
Replant Survival Rate.
| Variable, no. | Survival rate, no. (%) |
|---|---|
| Overall (n = 220) | 157/200 (71.4%) |
| Complete amputation (n = 152) | 96/152 (63.2%) |
| Partial amputation (n = 68) | 61/68 (89.7%) |
| Multi-digit replantation (n = 120) | 89/120 (74.2%) |
| Single-digit replantation (n = 100) | 68/100 (68.0%) |
Figure 1.
Number of digital replantation cases performed between 2001 and 2018.
Multivariate adjusted analysis revealed the following factors to be predictive of digit survival: sharp or saw mechanism of injury (P < .01), incomplete amputation with dorsal skin bridge or greater structures intact (P < .01), amputation proximal to zone I flexor level (P < .02), and post-operative acetylsalicylic acid use (P = .01). Need for leech therapy (P = .05) and need for re-exploration (P < .01) were significantly associated with final replant failure (Table 6).
Table 6.
Multivariate Analysis With Adjusted Binary Logistic Regression to Identify Perioperative Factors Predictive for Replant Success.
| Variable | Odds ratio (95% CI) | P value |
|---|---|---|
| Mechanism | 0.461 (0.287-0.741) | .001 |
| Complete vs partial | 3.678 (1.441-9.389) | .006 |
| Flexor level | 3.408 (1.542-7.532) | .002 |
| Acetylsalicylic acid | 3.535 (1.285-9.726) | .014 |
| Leech therapy | 0.489 (0.240-0.999) | .050 |
| Operative re-exploration | 0.162 (0.045-0.587) | .006 |
P value <0.05.
Replant success was compared between surgeons with and without additional hand surgery fellowship training and practice. No significant difference was found (P = .60).
In total, 73% of the replants (161/220) occurred overnight, where the majority of the procedure was performed between 7 pm to 7 am. Univariate subgroup analysis revealed no difference in survival between daytime and nighttime replants (P = .33), despite a shorter ischemia time for nighttime replants. This held true after controlling for confounders (eg, single- vs multi-digit replant, mechanism of injury, amputation level) using a bivariate logistic regression model. Nighttime procedure times were found to be significantly longer with mean duration of 9.6 ± 5.8 hours compared to daytime procedure with mean duration of 7.8 ± 3.7 hours (P = .01). The significance remained after controlling for confounders (eg, mechanism of injury, amputation level, single- vs multi-digit replant, partial vs complete amputation) using analysis of covariance. The nighttime group required more venous anastomosis, PICRA insertion, had more hand surgeon involvement, and post-operative leech therapy (Table 7).
Table 7.
Subgroup Analysis Comparing Daytime Versus Nighttime Digital Replantation.a
| Independent variable | Daytime n= 59 |
Nighttime n = 161 |
P value |
|---|---|---|---|
| Male | 57 (96.6%) | 143 (88.8%) | .075 |
| Diabetes | 3 (5.1%) | 10 (6.2%) | .754 |
| Coronary artery disease | 1 (1.7%) | 12 (7.5%) | .109 |
| Cerebral vascular disease | 0 (0%) | 0 (0%) | Insufficient number |
| Peripheral vascular disease | 0 (0%) | 0 (0%) | Insufficient number |
| Obesity | 1 (1.7%) | 9 (5.6%) | .219 |
| Smoking | 20 (33.9%) | 39 (24.2%) | .151 |
| Injured finger | .588 | ||
| Thumb | 22 (37.3%) | 43 (26.7%) | |
| Index | 8 (13.6%) | 20 (12.4%) | |
| Long | 14 (23.7%) | 46 (28.6%) | |
| Ring | 10 (16.9%) | 37 (23.0%) | |
| Small | 5 (8.5%) | 15 (9.3%) | |
| Heterotopic replant | 2 (3.4%) | 9 (5.6%) | .507 |
| Multi-digit injury | 40 (67.8%) | 117 (72.7%) | .479 |
| Multi-digit replant | 29 (49.2%) | 91 (56.5%) | .331 |
| Mechanism | .413 | ||
| Sharp | 6 (10.2%) | 19 (11.8%) | |
| Saw | 43 (72.9%) | 109 (67.7%) | |
| Avulsion | 5 (8.5%) | 22 (13.7%) | |
| Crush | 4 (6.8%) | 11 (6.8%) | |
| Complete amputation | 38 (64.4%) | 114 (70.8%) | .363 |
| Multi-level | 0 (0%) | 4 (2.5%) | .222 |
| Flexor level | .332 | ||
| I | 11 (18.6%) | 23 (14.3%) | |
| II | 46 (78.0%) | 124 (77.0%) | |
| III | 2 (3.4%) | 14 (8.7%) | |
| Surgeon number | .007 | ||
| 1 | 31 (52.5%) | 91 (56.5%) | |
| 2 | 22 (37.3%) | 39 (24.2%) | |
| 3 | 2 (3.4%) | 28 (17.4%) | |
| 4 | 4 (6.8%) | 3 (1.9%) | |
| Hand surgeon | 36 (64.4%) | 137 (85.1%) | <.001 |
| ASA class | .128 | ||
| I | 23 (39.0%) | 66 (41.0%) | |
| II | 35 (59.3%) | 77 (47.8%) | |
| III | 1 (1.7%) | 16 (9.9%) | |
| IV | 0 (0%) | 2 (1.2%) | |
| Artery anastomosis | .435 | ||
| 1 | 50 (84.7%) | 129 (80.1%) | |
| 2 | 9 (15.3%) | 32 (19.9%) | |
| Artery redo | .924 | ||
| 0 | 47 (79.7%) | 122 (75.8%) | |
| 1 | 7 (11.9%) | 19 (11.8%) | |
| 2 | 3 (5.1%) | 11 (6.8%) | |
| 3 | 2 (3.4%) | 6 (3.7%) | |
| 4 | 0 (0%) | 2 (1.2%) | |
| 5 | 0 (0%) | 1 (0.6%) | |
| Venous anastomosis | .010 | ||
| 0 | 28 (47.5%) | 42 (26.1%) | |
| 1 | 14 (23.7%) | 73 (45.3%) | |
| 2 | 14 (23.7%) | 38 (23.6%) | |
| 3 | 3 (5.1%) | 8 (5.0%) | |
| Vein graft use | 11 (18.6%) | 51 (31.7%) | .057 |
| Intraoperative heparin | 13 (22.0%) | 55 (34.2%) | .085 |
| PICRA | 39 (66.1%) | 137 (85.1%) | .002 |
| Acetylsalicylic acid | 52 (88.1%) | 146 (90.7%) | .577 |
| Heparin DVTp | 24 (40.7%) | 70 (43.5%) | .710 |
| LMWH DVTp | 5 (8.5%) | 17 (10.6%) | .0658 |
| DOAC | 0 (0%) | 2 (1.2%) | Insufficient number |
| Dextran | 13 (22.0%) | 55 (34.2%) | .080 |
| Heparin infusion | 9 (15.3%) | 39 (24.2%) | .154 |
| Leech use | 13 (22.0%) | 59 (36.6%) | .041 |
| Re-exploration | 3 (5.1%) | 13 (8.1%) | .449 |
| Digit survival | 45 (76.3%) | 112 (69.6%) | .330 |
| Age, mean ± SD | 39.7 ± 12.6 | 41.2 ± 16.1 | .539 |
| Operative time, mean ± SD | 7.8 ± 3.7 h | 9.6 ± 5.9 h | .034 |
| Operative time per digit, mean ± SD | 4.6 ± 2.0 h | 4.9 ± 2.2 h | .283 |
| Ischemia time, mean ± SD | 7.9 ± 3.9 h | 6.8 ± 2.6 h | .017 |
Abbreviations: ASA, American Society of Anesthesia Classification; DOAC, direct oral anticoagulation; DVTp, deep vein thrombosis prophylaxis; PICRA, post-operative infusional continuous regional analgesia; SD, standard deviation.
a Fisher exact test.
P value <0.05.
Discussion
Our institutional digital replant success rate was 71% over a 19-year study period. In comparison, Efanov et al from the University of Montreal, Canada, report a success rate of 73% over 2 years. 9 Their study was limited to complete amputations and is higher than our success rate of 63% for complete amputations. This may be attributable to the University of Montreal’s practice model where it acts as a regional replant centre covering 8.2 million individuals. The average annual digital replantation volume at this centre approaches 50 digits, which is significantly higher than our centre’s average of 11 digits per year. There is evidence to suggest superior outcomes in centres with higher replantation volume. 3,4,10 -12 Waikakul et al from Mahidol University, Thailand, published the largest retrospective series involving 1018 digits, averaging more than 85 digital replants per year and report a 92% survival rate. 10 It has been theorized that a Confucian moral value and greater emphasis on keeping a whole bodily appearance contribute to increased enthusiasm and volume for replants in Asian centres, especially in very distal amputations. 12,13 In contrast, there is a trend for decreased replant volume in North America. This is possibly due to decreased incidence secondary to improved safety precaution, lower remuneration, and diminished enthusiasm for achievable functional outcome. 14,15 A US epidemiological study noted the dawn of this phenomenon in 1996. The report showed that only 8% of hospitals performed digital replant. Of these hospitals, 60% performed 1 case per year and only 2% performed 10 cases or more. 16 Another review of 2 US level I trauma centres with an average of 17 digital replants per institution per year shows a success rate of only 57%. 15
Predictive Factors
Our results suggest that sharp amputations, more proximal amputation, intact venous drainage, and acetylsalicylic acid use are associated with increased replant survival. Need for leech therapy and operative re-exploration were significantly associated with eventually replant failure. The impact of injury mechanism and amputation level on replant success are well documented. 6,17,18 Zhu et al also reported a greater success rate in Tamai level II or more proximal level replants, likely due to greater vessel caliber facilitating technically easier repairs. 6 Amputation proximal to flexor zone III was not reviewed in our study because we felt the technical challenge of vascular repair at the digital vessel level is significantly different from vascular repair at the palmar and wrist level involving the palmar arches. Less consensus exists on the best post-operative anticoagulation regimen. Practice is largely surgeon and centre dependent. 2,19 The effect of aspirin on improving vessel patency rate has been demonstrated previously on rabbit ear models but no clinical effect as ever been found in replants up until our study. 20,21 In keeping with previous clinical recommendation by Buckley et al, 22 the most common anticoagulation regimen used by our centre was acetylsalicylic acid and subcutaneous heparin administered in deep vein thrombosis prophylactic dosage. Systemic heparin infusion was utilized based on the operating surgeon’s clinical judgment. Recent review by the provincial replantation centre at the University of Montreal, Canada, also supports the use of acetylsalicylic acid. They found that routine intravenous heparin use increases complication rates without significant benefit to the routine replant success rate. Its use should therefore be limited to select cases with increased risk of thrombosis and artery-only anastomosis replantation. 19,23 Leech therapy and operative re-exploration are both markers of a failing replant. Salvage rate after leech therapy for venous congestion approximates 50%. 24,25 Poor results after re-exploration are previously documented with some centres foregoing in-hospital monitoring of replants. 2,26 Factors that were found to be insignificant included age, sex, smoking status, surgeon subspecialty, number of venous anastomosis, vein graft use, ischemia time, and PICRA use. Post-operative infusional continuous regional anesthesia was used in 80% of our patient population. The effect of PICRA on sympatholysis and improving blood flow in replanted digits is well reported. 27,28 However, our finding is consistent with previous reports where PICRA’s physiologic benefit is not reflected in the final replant survival outcome. 29,30
Daytime Versus Nighttime Replant
Digital survival was not significantly different between daytime and nighttime replants. However, daytime replants trended toward a higher survival rate (76%) compared to nighttime replants (70%). This occurred despite nighttime replants having similar injury mechanisms and the advantage of significantly decreased ischemia time, more hand surgeon involvement, and more venous anastomosis. In addition, nighttime replants took significantly longer by an average of 108 minutes compared to daytime replants. This may be due to the absence of a dedicated plastic surgery nursing team familiar with microsurgical equipment and an increase in fatigue of the surgical team. This may have also resulted in the finding of significantly more post-operative leech requirements in the nighttime replant group. Most replants at our center occurred overnight (73%). It is likely due to the timing of most common work-related injuries and the additional transfer time required to arrive at the replant center. The literature consensus is that digital replantation is reliable within 24 hours of cold ischemia and 12 hours of warm ischemia. 7,31 Case reports demonstrate success with extremes up to 96 hours of cold ischemia and 33 hours of warm ischemia. 31 -33 A retrospective review by Cavadas et al showed that delaying nighttime replants until morning did not result in a significant difference in outcome. 8 However, their excellent survival rate (93.4%) in the delayed group may be attributable to the team having a high volume microsurgical practice with extensive replant experience and careful selection of patients.
Limitations
Our study is limited by its retrospective design. Replants were performed by a combination of on-call plastic surgeons with different subspecialty focuses and therefore outcomes may not be generalizable. Majority of replants occurred overnight. Outcome in this study is limited to replant survival at the time of hospital discharge. Long-term functional outcomes were not reviewed.
Summary and Future Directions
Over a 19-year study period, we found a 71% success rate over 220 digital replant cases. Sharp or saw mechanism of injury, presence of a dorsal skin bridge, amputation at a more proximal level, and post-operative acetylsalicylic acid use were found to be associated with increased replant success. Need for leech therapy and re-exploration were associated with decreased replant success.
This greater understanding of significant perioperative factors serves as a guide for future clinical decisions and for improving the replant protocol. Patients should be selected for mechanism and zone of injury. Initiation of acetylsalicylic acid should be considered in the post-operative period. Low replant volume favours consolidation of care into a specialized replantation centre. While our centre does not employ a nighttime delay protocol, comparison between nighttime and daytime procedures show no difference in survival rate despite longer ischemia time in the daytime group after controlling for other variables. Longer operative time was found in nighttime replants. The creation of an institutional overnight on-ice delayed replant protocol could be considered as a potential method to improve OR efficiency without compromising outcome. 8
Footnotes
Authors’ Note: Institutional review board approval (identification number: H18-02655) was obtained from the UBC Clinical Research Ethics Board. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5).
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
ORCID iD: Zach Zhang, MD https://orcid.org/0000-0002-0321-7825
Sheina Macadam, MD, MHSc https://orcid.org/0000-0003-0471-9584
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