Background

The mangled extremity can be defined as a combination of severe injuries to neurovascular, bony, and soft tissue structures in a limb. In the case of trauma with a mangled extremity, often patients require extensive concomitant resuscitation at the same time as damage control orthopaedics, which warrants the decision for amputation versus salvage, with four potential outcomes, including immediate amputation, successful salvage, failure of salvage with early amputation, and finally late amputation from complications. Amputation may be warranted in life-threatening cases but may have devastating functional consequences to the patient. On the other hand, attempts at limb salvage and reconstruction in itself may result in soft tissue complications and potentially mortality in the cases of reperfusion syndrome or infection, and a reconstructed limb does not necessarily equate to a functional limb. Thus, the decision of amputation versus salvage remains controversial[1]. 

The upper limb mangled extremity is significantly rarer in presentation when compared to the lower limb. Upper limb function is harder to replace with a prosthesis compared to the lower limb, and its preservation may have greater psychosocial implications. In addition, factors such as reperfusion time and soft tissue complications including crush syndrome are also significantly different between upper limb and lower limb injuries[2][3]. Thus, the decision of amputation in an emergency setting may become more difficult in upper limb cases. Currently, there are a few predictive scoring indices applied to the lower limb in practice, including the Mangled Extremity Severity Score (MESS) which was originally put forward by Johansen et al.[4] in 1990, as well as the Nerve Injury, Ischaemia, Soft tissue injury, Skeletal injury, Shock and Age of the patient (NISSSA) proposed by McNamara et al.[5] in 1994. and the Predictive Salvage Index (PSI) score which was proposed by Howe et al.[6] in 1987, with no widely accepted scoring systems or existing guidelines specifically designed for the upper limb.

This retrospective case series aims to: 1) determine the utility of MESS as a predictor for upper limb survivability versus amputation following trauma, 2) to identify specific factors in the decision for primary and secondary amputation including patient demographics, ISS scores,  mechanism and zone of injury and 3) to identify potential complications including infection, compartment syndrome, rhabdomyolysis, neurovascular complications etc. and their related management, including vascular and soft tissue interventions and osteosynthesis.

Methods

Data Collection and Study Design

The data of patients treated in Queen Elizabeth Hospital who were diagnosed with mangled upper limb extremity with involvement of vascular injury from Jan 2016 to December 2023 were extracted from the Clinical Management System of the Hong Kong Hospital Authority for the purposes of this study.  For demographic and initial presentation, their age, gender, energy of trauma, class of shock, zone and systems of injury involved, as well as the scoring systems Injury Severity Score (ISS), Gustilo-Anderson Classification and MESS scores will be analysed. Choice of treatment, rate of reoperation and complications will also be reviewed.

Inclusion and Exclusion Criteria

The inclusion criteria for patient selection include 1) age of presentation exceeding 18 years of age, 2) patients suffering from upper limb trauma involving two or more components (of musculoskeletal, neurological or vascular systems), 3) available reporting MESS and ISS scores, and 4) timing of admission between January 2016 and December 2023.  The exclusion criteria include 1) paediatric patients as they have significantly different physiology and disease patterns, 2) patients with concomitant lower limb mangled extremities, 3) patients suffering from isolated injuries distal to the wrist joint, and 4) incomplete records.

Primary and Secondary Outcomes

The primary outcome was whether MESS scoring accurately predicted the decision of amputation versus salvage. Secondary outcomes included factors influencing the decision of early and late amputation as well as incidence of complications and need for reoperation.

Ethical Consideration

Ethical approval for this study was granted by the Hospital Authority Central Institutional Review Board on 1st August, 2024. (Ref: IRB-2023-647).

Results

A total of 8 patients were within the identified 8-year time period who presented with an upper limb mangled extremity. All underwent trauma activation at the time of admission and were managed by the Advanced Trauma Life Support (ATLS) protocol. The mean age was 36 years (with a range of 25 to 77 years), with a male predominance of 7 males and 1 female patient. 62.5% of patients were active smokers at the time of injury. Three patients (37.5%) presented with ASA class V in a post-cardiac arrest status with priority for initial resuscitation, two others presented with ASA class II (25%), one with ASA class III (12.5%) and two with ASA class IV (25%). The initial haemoglobin level ranged from 10.2g/dL to 15.2g/dL.

Regarding the most proximal zone of injury, 1 case was at the level of the arm, 5 at the level of the elbow and 2 were at the forearm. 100% of cases experienced concomitant soft tissue and vascular compromise, with 7 cases (87.5%) presenting with the absence of distal pulses. Vascular injuries ranged from rupture in 25% of cases, most commonly at the level of the brachial artery near the bifurcation, cut injuries in 75% of cases ranging from the subclavian artery down to the radial and ulnar arteries at the forearm level, and avulsion injuries in 25% of cases of the ulnar and radial arteries at forearm level. All cases presented with an ischaemic time of less than 6 hours.

Table 1

Injury scores, zone and presence of pulse at the time of presentation

Figure 1

Regional and systemic injury scores for each patient

Table 2

Details on concomitant neurovascular, soft tissue and skeletal injuries of patients at the time of presentation

75% of cases experienced concomitant neurological injury, and 62.5% presented with skeletal injury, all of Gustilo III severity. All four components of musculoskeletal, neurological or vascular systems were involved in 50% of cases. The mechanism of injury varied from low to high energy trauma, with 3 cases of low energy trauma from direct cut or assault, with the remaining 5 cases from higher energy trauma: 2 cases being from industrial or machine-related injury, and 3 cases from road traffic accidents.

4 cases had MESS scores equal to or larger than 7. One case with a MESS score of 8 underwent successful primary reconstruction, and three cases underwent direct amputation. The decision for direct amputation among these three cases included:  two cases presenting with ASA 5 in post-cardiac arrest status and the highest ISS scores of 21 and 36 requiring resuscitation but resulting in same-day mortality, and the third case due to long segment avulsion of both radial and ulnar arteries and grossly contaminated soft tissue spanning mid-one-third length of the forearm which was not amenable to repair. Regarding the case of successful primary reconstruction, the patient presented with a high energy explosive injury to the forearm and elbow, with segmental injury of neurovascular structures, open fracture dislocation of the elbow and comminuted radial and ulnar shaft fractures. Repeated operations detailed (figure 3) were required for the staged reconstruction of the limb resulting in some restoration of upper limb function but residual joint contracture and partial nerve palsy.

Of the 4 remaining cases of MESS score of below 7, all underwent initial limb salvage and reconstruction. However, one case of MESS score 6 resulted in unsuccessful salvage with subsequent amputation. This patient suffered from avulsion of both ulnar and radial arteries, all musculature at the proximal forearm level and a comminuted fracture of the ulnar and radius at the mid-forearm level. Initial replantation of the forearm was attempted, which was complicated by post-replantation failure presenting with gangrenous changes over hands and digits and muscle necrosis, resulting in a below elbow amputation.

Three cases (37.5%) underwent secondary operations, two of who were in the initial salvage group with procedures including below elbow amputation for one case (the case of failed replantation) and repeated debridement, adjustment of external fixation and vascular intervention (in the case of explosive injury). The remaining case underwent debridement of open fracture and packing. Osteosynthesis was performed in 50% of cases. Soft tissue complications, both in the salvage group, presented in 25% cases including rhabdomyolysis, compartment syndrome requiring fasciotomy for release, tendon desiccation and contracture. Vascular complications presented in 25% of cases, including loss of distal circulation in the case of MESS <8 with failed replantation and high anastomotic tension with bleeder and pseudoaneurysm in the case of MESS >8. The average length of stay of cases undergoing eventual amputation was 7.5 days (+/-9.4) whereas it was lengthier at 25.5 days (+/-36.4) for the successful salvage group. The earliest return to work was 3 months in a case of reconstruction.

Figure 2

Outcome of cases and their respective MESS scores)

Table 3

Types of post-operative complications encountered

Figure 3

: 61/M construction site worker, smoker presenting with explosive injury and Gustilo IIIC distal radial and ulnar shaft open comminuted fracture and elbow dislocation, with rupture of the brachial artery and distal radial artery cut. External fixation, brachial artery repair with a great saphenous vein reverse vein graft and radial artery ligation were performed. Subsequent fasciotomy for compartment syndrome, osteosynthesis and repeated debridement were required. Vascular intervention was repeatedly required takedown of vein graft and re-anastomosis of bleeding flimsy anastomosis, and stenting after the development of pseudoaneurysm.

Discussion

Management of the upper limb mangled extremity may differ from that of the lower limb due to a few fundamental differences. Firstly, the upper limb is described to have better collateral circulation with recurrent arterial branches with numerous anastomoses with the brachial artery and elbow collaterals[1][2], thus less dependence on the viability of a single vessel and longer tolerable ischaemic time2. Secondly, due to the lower volume of muscle mass in the upper limb, it is less likely to experience crush syndrome and its related sequelae[3]. Thirdly, the upper limb can tolerate more bone shortening compared to the lower limb[4]. 

The MESS score was originally developed by Johansen et al. in 1990 and published in a retrospective review of patients presenting initially with lower limb mangled extremities. The scoring system is a summation of grades allotted to the energy of trauma, shock, age, and limb ischaemia, with the score doubled for ischaemic times exceeding 6 hours. The initial study concluded that the MESS cutoff of 7 had 100% predictability in the decision of amputation. However, potential advances in microvascular and soft tissue reconstructive techniques over the past three decades have suggested that previous cases deemed unsalvageable had increased chance of limb survivability, with studies e.g. Aarabi et al.[5] proposing a cutoff of 8 or above in 2016.

The MESS and four more scoring systems, including the PSI and NISSSA score were prospectively evaluated in the landmark Lower Extremity Assessment Project (LEAP) study of 556 patients suffering from high energy lower limb mangled extremities in 2001. This and a subsequent evaluation[6] suggested only 72% sensitivity and 62% specificity to predict amputation, and that none of the evaluated scoring systems were predictive of functional recovery in patients who underwent reconstruction of the lower limb. More recent systematic reviews have focused on the upper limb and suggested the low predictability of the MESS score of need for amputation. These include Nayar et al.[7] whom reviewed 15 studies of 6113 patients, and more recently this year, Yoneda et al.[8], who analysed 10 studies involving 338 patients and found that the pooled sensitivity and specificity for MESS were comparable to those reported for the lower extremities. The specificity suggests that limb salvage was achieved in at least 20 % of the patients whose MESS was above the threshold of 7. Given the likelihood of upper extremity functional limitations following amputation and the drawbacks of prostheses, it concludes that current scoring systems poorly predict salvageability and should not be used to justify amputation.

Potential drawbacks of the MESS scoring system include the failure to take into account the integrity of the vascular structures at the time of injury, energy of trauma and degree of soft tissue contamination and stripping. Avulsion injuries may cause more challenges as they often present as a high energy trauma with accompanying extensive soft tissue injury, and may require more advanced microvascular techniques in limb reconstruction[9]. Long segment avulsions may result in difficulty in determining the proximal extent of injury, and result in too much loss for direct repair warranting need for grafts or shunting. Concomitant nerve and tendon injuries may also result in less satisfactory functional outcome of the injured limb[10].  Regarding the case of unsuccessful initial salvage in the cohort with a MESS score <7, potential risk factors identified include active smoking status, the longest documented ischaemic time of 197minutes in the cohort, avulsion of both ulnar and radial artery and vein proximal to the amputation level and gross wound contamination. Similarly, avulsion of the radial and ulnar arteries, extensive stripping of surrounding muscles and gross wound contamination were present in the case of machine avulsion and MESS score <7 who underwent direct amputation.

Another potential drawback of the MESS scoring system is that it is designed to be applied only at the time of initial evaluation and does not guide subsequent treatment plans. In the case of limb reconstruction, patients are expected to have lengthier hospital stay due to the potential need for staged procedures including debridement, osteosynthesis, neurovascular and soft tissue reconstruction[11], each of which carry significant impact on the successful restoration of limb function, or the management of related complications as reflected in our sample group, particularly in cases of high energy trauma. Repeated need for microsurgical intervention may often lead to higher morbidity, cost[12][13] or an eventual dysfunctional limb.  Thus, Dirschl et al. [14] suggests that an a la carte basis should be employed, and existing scoring systems should not override clinical judgement.

There have been attempts in recent years to generate an upper limb-specific scoring system. Savetsky et a.[15] proposed a novel Mangled Upper Extremity Score (MUES) which assigned points for the injury characteristics of patient age exceeding 40 years; need for fasciotomy, bony fixation or revascularization; crush, degloving or avulsion injury present; bony defect present and soft tissue defect larger than 50 cm2. A MUES score of equal to or larger than 8 correlated significantly with the number of complications and length of hospital stay, whereas no correlation was found for the MESS. However, this study was confined to a single centre and limited sample size, and further study is needed to determine its validity.

The main limitations of this study are the small sample size and thus low power to demonstrate a statistically significant determination of MESS in the decision of amputation versus salvage, as well as the retrospective nature of the study. Due to the low incidence of this disease aetiology, multicentre patients may be recruited from a longer time period for further study.

Conclusion

The upper limb carries fundamental physiological differences, as well as functional and psychological utility that are not as replaceable with prostheses compared to the lower limb, making the management of the rarer upper limb mangled extremity challenging. Existing scoring systems, particularly the MESS score have low utility in predicting amputation versus salvage in such cases, and should only serve as a guide alongside clinical judgement. With advances in microvascular techniques and multidisciplinary trauma care, it prevails that clinicians should have a lower threshold for the attempt to limb salvage, but be vigilant for potential complications to provide timely relevant management.  Further studies with a larger patient population, and potentially the development of new scoring systems would be beneficial.