Composite grafts for fingertip amputations: a systematic review

There is debate in the literature surrounding the management of fingertip amputations. The role of composite grafts lacks clarity in terms of outcomes and complications. Hence, there is a need for an evidence synthesis to guide practice. A search of the databases OVID MEDLINE, PubMed, EMBASE, SCOPUS, The Cochrane Library, and clinical trial registries was conducted, from 1946 to January 2020, using the key terms “fingertip,” “digital tip,” “digit,” “finger,” “thumb,” “amputation,” “replantation,” “reattachment,” “reimplantation,” and “composite graft.” Studies reporting primary data on the outcomes of composite grafts of 5 or more digits were included. The studies included in this systematic review ranged in year of publication from 1959 to 2019. Data extraction included demographic details, functional, esthetic and adverse outcomes. Twenty-three articles were included. Outcome data on composite grafts are heterogeneous and little standardization of measurements exists, making interpretation challenging. Identified factors associated with improved outcomes include lower age, distal amputation levels by cut mechanism and decreased time to operation. Smoking is associated with poorer composite graft outcomes. Although survival rates vary greatly, composite grafting may be useful in certain cases and provide good functional and sensation outcomes with good patient satisfaction.

compliant with PRISMA guidelines [12] . A systematic review protocol was published [1] , and the systematic review was registered a priori: https://www.researchregistry.com.

Studies included
Original research studies of levels 1-5 of the Oxford Centre for Evidence-based Medicine [13] were considered for inclusion if they reported data concerning the relevant outcomes, as well as unpublished data, if methods and data were accessible. No duplicate articles nor articles not reporting primary data were included.

Participants
The patient population included children and adults receiving nonmicrosurgical replantation following distal fingertip amputations, with the aim of reviewing outcomes in these cases in order to elucidate the role of non-microsurgical replantation in the management of distal finger amputations.

Intervention
The interventions included were composite grafting of the distal tip via non-microsurgical methods following fingertip amputation. Any studies in which microsurgical reconstruction was used were not included. Articles were included if they reported on the survival outcomes of distal fingertip amputations treated with primary composite grafting of the amputated tip. All articles using subcutaneous pocket techniques, "pulp flaps" or microsurgical replantation were excluded, as were articles reporting on data of <5 cases, following previous research [9] .

Outcomes
The primary outcome measured was graft survival. Secondary outcomes are detailed below.

Identification and selection of studies
Two independent reviewers (M.R.B. and M.L.L.) screened the title and abstract of each of the published articles for inclusion according to the criteria listed in Tables 1-2. Full-length manuscripts were reviewed for articles which met the inclusion criteria, if no abstract was published or if the abstract did not have sufficient information to determine eligibility.

Quality scoring
The Grading of Recommendation Assessment, Development and Evaluation (GRADE) system was used to assess the methodological quality of included studies.

Analysis
Characteristics of included studies are presented as counts and percentages. Continuous data are expressed as means (or median values where stated). Meta-analysis was not performed as only one study reported comparative data on outcomes of composite grafting compared to other methods of managing distal fingertip amputations.

Results
The search yielded a total of 5790 articles, after 2061 duplicates were removed, 3729 underwent title and abstract screening (stage 1), and 119 articles underwent full-text screening (stage 2). A total of 23 articles met the full inclusion criteria (Fig. 1) [10, .

Article demographics
The articles included covered data collection from 1959 to 2019 (Table 3). The majority of the work published on composite grafting outcomes was conducted in Japan (n = 5), followed by the United Kingdom (n = 4) and the USA (n = 4), Korea (n = 3), Italy (n = 3), Australia (n = 1), Taiwan (n = 1), Turkey (n = 1) and France (n = 1). The highest level of evidence of our included studies was 4, corresponding to a randomized controlled trial (RCT) by Kusuhara et al [29] . In terms of article quality, every study had a GRADE score of "very low", with the exception of the aforementioned RCT conducted by Kusuhara et al [29] which was graded as "moderate".

Patient demographics
In total, the number of reported patients included across all studies was 810, with 264 females (Table 4). In addition, Urso-Baiarda et al [35] reported on 108 digits and Imaizumi et al [26] on 18 digits, with the number of patients not specified. The mean age of participants per study ranged from 2.4 [32] to 43.2 years [28] (range 0-74) [28,32] and each article reported on anywhere from 7 to 108 digits, with a mean of 41.5 digits [33,35] . The majority of included studies reported on outcomes of a single digit composite grafting per study participant, with five articles reporting outcomes of more than one digit per patient [17,22,24,28,34] .

Surgical technique
Surgical technique and reporting on specific operative details varied (Table 5). Classic composite grafting (ie, no modifications) was the most commonly used method, with 19 of the included articles adopting this technique [10,[14][15][16][18][19][20][21][22][23][24][25][26][28][29][30][31][32]34] . The cap technique, whereby the proximal stump is de-epithelialized and the amputated part modified so as to allow for maximal contact between the stump and amputated part, was adopted in three studies [17,27,33] . Fingertip amputations (ie, distal to the DIPJ) almost always involve the nailbed, however, only 11 of the 23 studies specifically describe repair of the nail bed [14][15][16][17][18]20,22,[25][26][27]31] and Murphy et al [32] describe removal. Part of the management (and "preservation") of the nailbed involves management of the nail; the nail may be removed and sutured back onto the nailbed to act as a splint to guide new nail growth or discarded due to contamination. When discarded, other material (most commonly foil) can be used as a splint, or surgeons may not use a splint at all. Three of the 12 articles mentioning nailbed management describe removing and resuturing the nail bed [22,26,31] . Dagregorio and Saint-Cas [18] and Chen et al [17] stated that the nail bed was preserved. Proximal part trimming was only reported in 3 articles, that is those using the cap technique [17,27,33] .

Functional outcomes
In total, ten studies reported on the functional outcomes following composite grafting [14][15][16][17][18][19]25,27,30,31] (Table 9). Losco et al [30] were the only authors to use objective measure, and graded functional recovery using the Q-DASH score and measured movement at the IPJ. The results of this indicates minimal disability [30,41,42] but with lessened motion at the IPJ [43] . The other studies recorded functional outcomes with questionnaires, however, each study used a unique questionnaire with different questions [15][16][17]30,31] . Results based on clinician reports showed that all patients used their hands normally or that all digits were functional [14,18,25,27] with the exception of Douglas [19] , who only reported on functional outcomes of 2 patients. Of the 4 articles that reported on patient satisfaction with the results, the responses were favorable and showed that the majority of patients were pleased with the end result [15,17,27,30] .

Discussion
Composite grafting is a simple technique for restoring the amputated fingertip in cases where microvascular replantation is not possible. This technique has most frequently been used to repair pediatric fingertip amputations due to the small caliber of affected vessels and the relative regenerative capacity of juvenile tissues [7] . To date, there has been no formal synthesis of results across individual studies. Therefore, we conducted the first systematic review of composite grafting for distal fingertip amputations to investigate whether it is a viable and worthwhile technique and what factors are most predictive of graft survival. A total of 23 individual studies were reviewed in this systematic review. Across all studies, the success rates of composite grafting were highly variable, ranging from 7.7% [20] to 93.5% [17] . Adverse outcomes were common with infection rates as high as 17% [15] and reoperation rates of up to 56.3% [23] . The functional and sensory outcomes were favorable with high patient satisfaction. However, cosmetic outcomes were not optimal as detailed from the questionnaire responses and clinical reports, which show that finger shortening, and nail deformities are common. However, and importantly, the evidence available to date was of poor quality. Indeed, only one study was the level 1a (the highest level) according to the Oxford criteria. This study by Kusuhara et al [29] ; however, this study did not compare composite grafting to alternative methods for managing fingertip amputations not suitable for replantation (ie, stump management by primary closure), but rather compared success of grafting with and without application of b-FGF. In fact, no comparative studies looked at outcomes of composite grafts versus not grafting, and the majority of published articles were retrospective case series Idone et al [25] Classic - Borrelli et al [15] Classic <  (level 4) [10,14,15,[17][18][19][20][21]23,[25][26][27][28][30][31][32]35] . Another factor limiting study was the low participant number. A minority of available studies included > 50 patients [15,16,21,22,31,32,34,35] . A major outcome of this systematic review was to investigate factors predictive of graft survival. Smoking status and comorbidities are relevant when using composite grafting on adult patients. Of the 17 studies reporting results with adults, only 7 studies reported on smoking or comorbidity status [10,15,21,22,27,30,35] . The studies that did report on smoking found, not surprisingly that smoking was associated with poorer outcomes. A multivariable analysis [22] found that smoking was an independent factor associated with poorer graft healing. Better graft survival has been linked to decreased time to operation [31] , lower age [15,16] , clean-cut injuries [21,28] , and more distal amputation levels [16,28] . These findings, in addition to future research, should help clinicians in stratifying patients to being at high risk of poor outcomes from composite grafting. A variety of operative techniques were described, including classic composite grafting and the cap technique. The cap technique has been shown to aid healing through providing increased contact surface between the stump and amputated part. However, the main limitation of this technique is the resulting finger shortening, which, depending on patient and injury factors, may be significant.

Sutured
A secondary outcome investigated was predictors of poor postoperative outcomes. Adverse events following composite Table 6 Adverse outcomes.

Moiemen and
Elliot [31] Parental Questionnaire --Tender tip: 10 (26%) Pain cutting nail: 8 (21%) Adani et al [14] Clinician report & 2PD < 7 in all patients 2 y None complained of dysesthesia or cold symptoms Kankaya et al [27] Questionnaire & 2PD 7.26 6 mo Zone I (n = 2): Pain and cold intolerance were ameliorated after 2 mo Zone 2 (n = 15): Patient satisfaction on pain, sensibility, cold intolerance was achieved Zone 3 (n = 6): Patients had neither pain nor cold intolerance by the third postoperative month Eo et al [10] 2PD 5.5 -Some complained of persistent paraesthesia Chen et al [17] Questionnaire & 2PD 6.3 6 mo Numbness over the fingertip: 19 (65.5%) Fingertip tenderness: 4 (13.8%) Butler et al [16] Parental Questionnaire --Scar tender: 3 (7%) Cold intolerance: 7 (17%) Hypersensitive: 3 (7%) Idone et al [25] 2PD < 5 in all -No patient complained of dysesthesia or cold intolerance Borrelli et al [15]  grafting were inconsistently reported among the included studies and only 17 articles reported adverse events [10,[15][16][17][18][19][20][21][22][23][24][26][27][28]30,32,33] . The overall complication rate was 15.6%. The recovery of composite grafts from the data indicate that adverse effects such infection and necrosis are common and that reoperation mostly consists of debridement or the use of additional skin graft or flap procedures [10,[15][16][17][18][19][20][21]23,24,27,30,32,33] . One striking finding of this review is the huge variety in the small number of published studies. Interestingly, in the 23 of studies, 6 different classification schemes were used to describe the level of amputations. One of the more commonly used, the Ishikawa classification adapted to distal fingertip amputations, categorizes amputations in terms of zones of the fingertip based on the nail. It comprises four zones distal to the DIPJ and takes into account the angle of the amputation [36] . The Hirase classification [23,24] is based on the course of the digital artery, whereas the Allen classification includes reference to bony fragments in the amputated stump and advice for management based on the level [37] . Moreover, descriptions of the types of injuries sustained were not reported in a standardized fashion and five articles did not classify the mechanism of injury [23,24,27,29,35] . Finally, the definition of graft survival, the main outcome investigated, also significantly varied between studies. One of the main limitations in the data is the reporting of the composite graft healing. Success or failure or graft take is defined differently Table 9 Functional outcomes and patient satisfaction.

Measurement
Method Results

Patient Satisfaction
Douglas [19] Clinician report Case 3: negligible stiffness Case 4: ankylosis at distal joint -Moiemen and Elliot [31] Parental Questionnaire Difficulty cutting nail: 11 (29%) Digit use "normal": 34 (90%) -Adani et al [14] -All patients used their hands normally -Kankaya et al [27] Clinician report -Zone 1: full functional and aesthetic satisfaction Zone 2: satisfaction with aesthetic and sensation outcomes Zone 3: -Dagregorio and Saint-Cast [18] Clinician report All fingers were functional -Chen et al [17] Questionnaire 4 (13.8%) experienced limitation in use of hand Very satisfied: 24 (82.8%) Moderately satisfied: 2 (6.9%) Slightly satisfied: 1 (3.4%) Completely unsatisfied: 2 (6.9%) Butler et al [16] Parental Questionnaire 2 parents (5%) reported functional deficit Parents reported ∼45% complete graft survival Idone et al [25] Clinician report All patients were able to normally use their digits also for pinching and picking up small objects -Borrelli et al [15] Questionnaire Time before using hand/finger in normal activities:  Figure 2. Mean percentage of composite graft survival/take/ success [10,[14][15][16][17][18][19][20][21][22]25,[27][28][29][31][32][33][34] . Revision operation rate (%) Figure 3. Mean revision rate [10,[15][16][17][18][19][20][21]23,24,27,30,32,33] . across the included studies, making comparisons of success rates difficult. As an example of this, a few studies define complete or partial take as success, while others do not. This is reflected in the broad range of success rates across the data which vary from 7.7% [20] to 93.5% [17] . Details of postoperative care such as assessments of recovery and postoperative instructions were also varied and could add significant variability. Despite this heterogeneity making it difficult to compare results and synthesize data across studies, the results from the 23 articles included in this review suggest that composite grafting is a successful management technique for distal fingertip amputations not for microsurgical reconstruction and often yields good functional and sensation outcomes. Cosmetic outcomes may not be optimal; however, this must be considered against the outcomes from primary closure of the stump, which results in loss of the nail complex. Future studies should be additive or adopt previously used classification systems, such as the Ishikawa, which has the advantage of detailing the angle of amputation, which may be significant. Furthermore, future work should use clear definitions of graft success to facilitate homogeneity.

Conclusions
Composite grafting may be a useful technique in the management of distal fingertip amputations in adults and children when microsurgical anastomosis is not possible and may yield good functional and sensation outcomes with good patient satisfaction. However, cosmetic outcomes are less successful, with nail deformity and digit shortening commonly reported. Adverse outcomes are also commonly reported. Current available evidence suggests that composite grafting success is higher in children with more distal amputation levels by a cut mechanism who undergo composite grafting within a few hours from injury. The current available data on composite grafting for distal fingertip amputations is extremely heterogenous and synthesis of results is difficult for this reason. Little standardization exists for detailing injury, amputation, operative or follow-up information and several classifications systems are used. How optimal healing is defined is also a major limitation to interpreting the success of composite grafting. This is reflected in the rates of composite graft take, which vary widely. Further research should aim to address this by using standardized methods of collecting data. Digit shortening (mean, mm) Figure 4. Mean digit shortening [15,27,30,33] . Two-point discrimination (mean, mm) Figure 5. Mean 2-point discrimination [10,17,27,30,33] .