Outcomes of Popliteal Artery Injuries in a Level 1 Trauma Centre: A 6-year review

doi:10.21203/rs.3.rs-5246689/v1

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Outcomes of Popliteal Artery Injuries in a Level 1 Trauma Centre: A 6-year review

https://doi.org/10.21203/rs.3.rs-5246689/v1

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Purpose

To determine modifiable and non-modifiable factors contributing to limb loss in PAI the relevance and accuracy of published scoring systems for PAI within a South African State hospital.

Methodology:

Retrospective review of patients (> 18 years) with PAI, presenting to CMJAH trauma unit from 1 January 2017 to 31 December 2022.

Results

Sixty-four patient records were analysed. Thirty (46.9%) had blunt trauma and thirty-four (53.1%) had penetrating trauma. Gunshot wounds (GSW) were the most common mechanism of injury (MOI). Blunt PAI had a 40% amputation rate and penetrating trauma, 33.3%. Forty-seven (73.4%) had a delay to surgery of > 6 hours. The mean time to arrival at our emergency department was 478 min, and the mean time from arrival to surgery was 368 min (total delay of 838 min). The primary amputation rate was 28.6%, and 63.5% had successful limb salvage surgeries. The secondary amputation rate was 7.8%.

Conclusion

Compared to international literature, our rate of primary amputation is high (10% vs 28.8%) and prolonged ischaemia is the likely cause. Only 17 (26.6%) patients presented before 6 hours. Of the 45 patients that had an attempt at revascularisation, 7.8% had a secondary amputation. Thus, despite prolonged ischaemia, revascularisation should be attempted in patients with at least two viable compartments on fasciotomy. The MESS and POPSAVEIT scoring systems should not be relied on in patients with delayed presentations. Strengthening referral triage for suspected PAI to Level 1 Trauma centres directly will decrease the delays and likely improve the outcomes.

Popliteal artery

Injury

Trauma

Developing country

Outcome

Globally, Popliteal Artery Injuries (PAI) are considered uncommon. Concomitant bony or soft tissue injuries occur and PAI rarely occur in isolation. This results in high rates of morbidity, limb loss, functional disability and mortality [1]. Hafez et al, reported that above knee popliteal artery injuries carried the highest rate of limb loss (25.6%) in all lower limb arterial injuries [2]. South Africa is a low-middle income country and vascular injuries such as PAIs are a major contributor to limb loss [3] and although uncommon, they place a significant burden on scarce resources. Traumatic injuries in South Africa account for many admissions yearly. Furthermore, PAI specifically, is an injury that mainly afflicts people in their young adult life during their most economically productive years, and this further impacts the broader society as this population forms the largest part of our income earning-working cohort.

Blunt trauma has previously been considered to be the leading cause of PAI’s, accounting for up to 75% of all cases of PAI’s worldwide [4]. These types of injuries also historically result in higher amputation rates when compared to penetrating trauma [1], [5], [6]. This have been thought to be due to the higher transmitted impacts and larger forces experienced during blunt trauma, resulting in significant damage to structures outside of the vessels, like bones, soft tissue and nerves. These associated injuries also make successful limb salvage less likely as it decreases the likelihood of patients having a functional limb, even with successful vascular repair [6].

Our South African context has an increased experience with patients with penetrating trauma. As such, we expected to find a higher incidence of PAI’s in penetrating trauma victims. However, we were of uncertain opinions as to the contribution penetrating PAIs to morbidity and mortality and overall outcomes. A previous study performed at Chris Hani Baragwanath Academic Hospital in Soweto reflecting on this higher incidence of penetrating trauma, found an overall amputation rate of 14% [7], however, this study made no mention of PAI’s secondary to blunt trauma. To compare this to international literature, the United States of America National Trauma Data Bank from 2003 reported a 9% amputation rates for their review of penetrating PAI involving combined arterial, venous and nerve injury [1].

One cannot look at PAI of any cause without looking at the impact of delays to surgery on overall outcomes especially amputation rates. Time delays to surgery are routinely discussed in conjunction with outcomes in popliteal artery injuries. The initial 6-hour period was first described in 1949 as the absolute limit for successful revascularization and limb salvage, and this “golden period” is often considered in conjunction with early versus late fasciotomies and the potential limb salvage rates and benefits of either option [8]. Prolonged delays in surgical time have routinely been demonstrated by past authors to adversely affect limb salvage rates with some studies finding a 65% increased risk of primary amputation for every 6 hours delay to surgery [9]. A study performed in Cape Town, South Africa, concluded that the most significant factors associated with their high amputation rate of 37.5% was an ischemic time longer than seven hours [10]. Therefore, it is believed that by decreasing ischemic time from arrival to restoration of perfusion, there will likely be improved outcomes and increased limb salvage [8].

Another relevant consideration to outcomes of PAI’s is the choice of early fasciotomy and this has been investigated in patients with PAI’s [11]. This practice is considered a modifiable risk factor in relation to these injuries. There have been further studies that demonstrate an increase in the risk of significant limb ischemia in the presence of severe soft-tissue trauma, especially in the blunt injury profile, and in association with acute compartment syndrome.

The type of surgeon performing the vascular repair, either trauma surgeon or vascular surgeon, as demonstrated by Kr\(\:ü\)ger et al also plays a role in the outcome of these patients with the findings of improved outcomes in patients operated on by vascular surgeons [12].

The MESS was developed in 1990 to determine the likelihood of successful limb salvage in patients with mangled extremities [13]. However, the validity of this scoring system has subsequently been questioned by Gratl et al and trials such as the lower extremity assessment project (LEAP) [14], [15]. A team-approach involving experienced surgeons is recommended for decision-making regarding amputation as the MESS scoring system has a limited predictive value in PAI [16]. The POPSAVEIT scoring system was developed in response to the lack of other validated scoring systems in predicting amputation risks in PAI’s [17]. This scoring system aims to risk stratify patients in a pre-operative setting. A high score (of ≥3) had a sensitivity of 89% and a specificity of 47% for amputation. However, it is important to note, that even in patients with a maximum score of 5, the predicted risk of amputation is still less than 50%. The MESS and POPSAVEIT scoring systems have routinely been used as a method to predict the risk of amputation in patients with PAI’s. However, the accuracy of these scoring systems in resource constrained settings is unknown. Therefore, we aimed to investigate both scoring systems to assess their reliability and accuracy within our own context, especially in comparison to our own gold standard of assessing muscle viability prior to any revascularization attempt with the use of a fasciotomy.

Thus, it was our objective to interrogate factors that contribute to poorer outcomes in PAI’s,

especially amputation rates. We wanted to determine which of these factors can be modified or improved upon within a South African setting. We also aimed to assess the validity of universally accepted scoring systems to patients in the South African setting.

We performed a retrospective analysis of data from patients seen at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) trauma unit over 6 years (from 1 January 2017 to 31 December 2022). Data was collected from MediBanks (this is an electronic record, completed when patient is seen) and patient files obtained from the Trauma Surgery Department, as well as from the online database of patient files.

In our study population, we included all patients admitted and managed by the CMJAH trauma unit older than 18 years of age, during the specified time. From our initial data collection, we had identified 80 patients suitable for our study. From this initial number, 16 patients had to be excluded as depicted in Fig. 1. Of note, 1 patient demised on table prior to any surgical intervention and was included as a mortality. To clarify, information on the outcome variable of amputation will have data on 63/64 patients while information on the outcome variable of mortality, has data for all 64 patients.

All statistical tests were performed using STATA/SE 17.0. Categorical data were described by means of frequencies (actual numbers) and percentages. The Shapiro-Wilk test and graphical methods (histograms and normal probability plots) were utilised to carry out tests for normality. Medians and interquartile ranges (IQRs) were utilised to describe the data. Tests for association for categorical data were carried out using the Pearson's Chi-Square and/or the Fisher's Exact test. The significance level was set at a P < 0.05. Sensitivities and specificities of the x and y scoring systems were also reported for the outcome variables of amputation and mortality.

We obtained ethical approval from the Gauteng Health Research Committee as well as from the Wits (University of Witwatersrand) Human Research Ethics Committee (HREC).

Sixty-four patients with a PAI were included in the study, of which 52 (81.3%) were male and 54 (84.4%) were under the age of 50 (Table 1). Of these, 41 (64.1%) had isolated limb injuries and notably, 1 patient demised prior to any surgical intervention and was included as a mortality.

Blunt PAIs accounted for 30 (46.9%) of the PAIs whilst penetrating injuries resulted in 34 (53.1%) injuries (Figure 2a,b). Forty-eight (75.0%) of our patients had associated fractures, and of these fractures, 14 (21.9%) were tibial plateau fractures and 13 (20.3%) had associated knee dislocations (Table 1). Fifty-six patients (87.5%) had absent pulses on clinical examination. Furthermore, 17 of the patients (26.6%) had absent doppler signals in the emergency department. Computer tomography (CT) scans were performed in 50 (78.1%) patients.

Forty-seven patients (73.4%) had a delay from time of injury to time of surgery of more than 6 hours. The median delay from time of injury to time of arrival at the emergency department was 478 minutes (IQR= 70-625). The median time from arrival at hospital to time of surgery was 368 minutes (IQR= 127.5-565).

In the group of patients who had a delay to surgery of more than 6 hours, 19 (40.4%) patients had eventual amputations. The rate of amputation amongst the 23 patients who were operated within 6 hours was 17.4%, however this was not a statistically significant difference (p= 0.371).

Eighteen (28.6%) of our patients underwent a primary amputation whilst 45 (71.4%) had a revascularization attempt using Reverse Saphenous Vein Graft (RSVG). No other surgical conduits (such as polytetrafluoroethylene (PTFE) grafts, primary repairs, or temporary shunts) were utilised.

In the group of patients with blunt trauma 40.0% had amputations whilst in the penetrating group there were 33.3%, but we found no statistically significant difference between the two (p=0.611). Thirty-four patients had penetrating injuries. Of these 8 (23.5%) had a primary amputation, of which 22 had a RSVG interposition, whilst 3 patients requiring a delayed amputation after an initial revascularization and fasciotomy. Thus, 11/33 (33.3%) had amputations.

Thirty patients had blunt injuries. Of these 10 had a primary amputation, 20 had a revascularization, with 2 (6.7%) of the patients requiring a delayed amputation after revascularization and fasciotomy. Patients involved in MVA’s, had an amputation rate of 16.7%, whilst in patients involved in a PVA, 4 (66.7%) had amputations. In patients falling from a height (FFH) 1 (20.0%) had amputations. All three patients who sustained injuries by falling from a moving train, had eventual amputations.

In patients with knee dislocations secondary to blunt force trauma (total = 13 patients), 3 (23.1%) patients had amputations. In patients with concomitant fractures and an arterial injury, 18 (37.5%) had eventual amputation and 4 (28.6%) of patients with tibial plateau fractures eventually underwent amputations. Again, no statistical difference was found in those with these associated injuries and those without, in terms of amputation risk.

Of the 45 patients who underwent a RSVG revascularization by vascular surgery, 5 (11.1%) had to undergo a secondary amputation. Thus 40/63 (63.5%) had successful limb salvage and the amputation rate was 36.5% (23/63). The mortality rate was 6.3%.

In the blunt trauma group, there were no mortalities compared with the penetrating trauma group where there were 4 mortalities (p= 0.116). In terms of a delay to surgery, this did not have any effect on mortality, with all the mortalities undergoing surgery within 6 hours of their injuries. Three of the patients who demised had concurrent orthopaedic fractures (p= 1.00), with only one of these patients having a tibial plateau fracture and none of them having knee dislocations.

In the POPSAVEIT score (Table 3), a score of ³3 is considered high risk. Forty-one (64.1%) patients had a score of ³3, indicated a strong likelihood of amputation, however, only 23 (36.5%) patients in total went on to have an amputation, 17 (73.9%) of those being in the high-risk categories, and 6 (26.1%) being considered of low risk. A MESS, score of ³7 is considered high risk for amputation, and 31 (49.2%) patients had a high-risk score in this study, while again, in the high-risk category 14 (45.2%) had actual amputations (Table 4). In our cohort, neither the POPSAVEIT not the MESS scores were accurate predictors of limb salvage or an amputation (Table 5).

Popliteal artery injuries though uncommon are associated with high rates of amputation. Amputation rates for the civilian popliteal injuries have previously been reported to be between 14.5% and 25% and for the military population, it was found to be up to 30% [18].

In patients who have successful limb salvage, concomitant orthopaedic injuries prolong rehabilitation and return to full ambulatory function. Furthermore, PAIs place a significant burden on scarce resources which is more pronounced in resource poor health systems. Outcomes in PAIs are determined by a composite of inputs including systems factors and patient factors. The system factors are pre-hospital referral pathways, in-hospital triage systems, technical surgeon competencies. Patient related factors include mechanism of injury (MOI), other associated injuries, and patient co-morbidities. As such, ours is an important study as it aimed to define the various factors with a view to improving outcomes.

We performed a retrospective study of 64 PAIs in a tertiary government funded Level 1 trauma referral centre in Johannesburg. Although the literature is replete with case series of PAIs, there is a paucity of information from resource constrained environments where vascular surgical emergency services are provided by vascular surgeons and not general surgeons. We found a primary amputation rate of 28.9% (18 patients) and this was within the context of 71% (46 patients) presenting after 6 hours.

In a large retrospective series (164 patients) from Cape Town, Banderker et al described a low primary amputation rate of 5% but an overall amputation rate of 37% [10], and a smaller series from the West Indies with an overall amputation rate of 28% [19]. Our overall amputation rate was 36% and this was in keeping with the Cape Town Study. A contemporary large study in America reports a 16% amputation rate [17].

In our study, only 23 patients arrived at the hospital within 6 hours, and their amputation rate was 17.4% which is in-line with contemporary literature from first world countries, whereas in ours and the Cape Town experience, most patients arrived and were operated on after 6 hours (mean 14 hours in our study). Thus, modifiable outcomes in popliteal injuries are largely determined by pre-hospital factors, and this is where the focus should be. Awareness of possible popliteal artery injuries within the 1st responder communities needs to be increased and triage systems require the inclusion of PAIs as ‘P1’ injuries requiring immediate transport to the appropriate trauma centres. A mechanism of injury consistent with a PAI in combination with no pulse should be referred directly to the appropriate centre.

There are however some positives to take home in our results. Of the 47 patients who had a delayed presentation to hospital (> 6 hours), 28 (60%) had successful limb salvage. Our policy is to offer all patients a fasciotomy (even those with no motor or sensation), and in patients who have only 2 non-viable compartments (of 4), to offer them a trial of revascularisation and relook their muscle compartments after 48 hours. In patients with 3 or all compartments non-viable on fasciotomy, we perform a primary amputation. Even though the delay to revascularisation was long in our patient cohort, in those who had a delayed revascularisation very few required a secondary amputation (11%). Additionally, all patients had a RSVG. The vascular surgical literature is overwhelmingly in support of a single segment RSVG in below knee revascularisations as it has better patency [20], and our data demonstrates that even in a trauma cohort a saphenous vein graft can be found in most patients.

Furthermore, we found that the common risk prediction scores for popliteal injuries were inaccurate in our setting as they were not validated in environments with such a long delay to revascularisation. The POPSAVEIT score was a multi-centre study including 355 patients where a score of more than 3 predicts an amputation [17]. However, in this cohort only 33% of patients were revascularized after 6 hours. Both the MESS and the POPSAVEIT score were poor in predicting an amputation.

Thus, scoring systems may predict patients at high risk but their clinical applicability cannot be relied upon, and our policy of muscle assessment through a fasciotomy should be considered the gold standard and cannot be replaced by scoring systems.

LIMITATIONS

Ours was a retrospective study and relied upon findings documented at the time of presentation. Also, we described only short-term outcomes and were unable to describe how many patients returned to function.

PAIs injuries occur predominately in young males, and in LMICs where manual labour is a means to income for most, limb salvage is even more critical. In HICs, rates of amputation have decreased to approximately 16–20%, largely due to the decrease in time of revascularisation. Pre-hospital systems require strengthening in order to save limbs. Fasciotomies and muscle assessment should be attempted in all patients with marginal features of limb viability, as limb salvage rates are still acceptable in this cohort.

There were no conflicts of interest during this study.

Author Contribution

K.V.R, W.S, I.C. wrote the main manuscript textK.V.R and W.S. collected all the data K.V.R and W.S. prepared all figuresAll authors reviewed the manuscript

Acknowledgements:

We would like to thank the Wits Surgical Statistical Hub for their help with our statistical analysis.

Data Availability

The data that supports the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon request.

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Table 1 to 5 are available in the Supplementary Files section.

No competing interests reported.

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You are reading this latest preprint version

Outcomes of Popliteal Artery Injuries in a Level 1 Trauma Centre: A 6-year review

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Abstract

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INTRODUCTION

METHODOLOGY

RESULTS

DISCUSSION

LIMITATIONS

CONCLUSION

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Author Contribution

Acknowledgements:

Data Availability

References

Tables

Additional Declarations

Supplementary Files

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