a b s t r a c t

Introduction: Field amputation can be life-saving for entrapped patients requiring surgical extrication. Under these austere conditions, the procedure must be performed as rapidly as possible with limited equipment, often in a confined space, while minimizing provider risk. The aim of this study was to determine the ideal saw, and optimal approach, through bone or joint, for a field amputation.

Methods: This was a prospective cadaver-based study. Four saws (Gigli, manual pruning, electric oscillating and electric reciprocating) were tested in human cadavers. Each saw was used to transect four separate long bones (humerus, ulna/radius, femur and tibia/fibula), previously exposed at a standardized location. The time required for each saw to cut through the bone, the number of attempts required to seat the saw when transecting the bone, slippage, quality of proximal bone cut and extent of body fluid splatter as well as the physical space re- quired by each device during the amputation were recorded. Additionally, the most effective saw in the through bone assessment was compared to limb amputation using scalpel and scissors for a through joint amputation at the elbow, wrist, knee and ankle. Univariate analysis was used to compare the outcomes between the different saws.

Results: The fastest saw for the through bone amputation was the reciprocating followed by oscillating (2.1 [1.4-3.7] seconds vs 3.0 [1.6-4.9] seconds). The manual pruning (58.8 [25-121] seconds) was the slowest (p = 0.007). Overall, the oscillating saw was superior or equivalent to the other devices in number of attempts (1), slippage (0), quality of bone cut (100% good) and physical space requirements (4500 cm³), and was the sec- ond fastest. In comparison, a through joint amputation (125.0 [50-147] seconds for scalpel and scissor; 125.5 [86-217] seconds for the oscillating saw) was significantly slower than through bone with the Gigli (p = 0.029), the oscillating (p = 0.029) and the reciprocal saw (p = 0.029).

Conclusions: The speed, precision, safety, space required, as well as the adjustable blade of the oscillating saw make it ideal for a field amputation. A Gigli saw is an excellent backup for when electrical tools cannot be used. Through bone amputation is faster than a through joint amputation.

(C) 2021

1. Introduction

Surgical limb amputation is required in the management of approx- imately 1% of all trauma patients [1,2]. While there is a paucity of infor- mation specific to field amputation, Livingston et al. provided a retrospective review of 42 patients with traumatic amputations, in which 53% required below-knee amputations, 19% below-elbow ampu- tations, 17% above-knee amputations and 11% above-elbow

* Corresponding author at: LAC + USC Medical Center, 2051 Marengo Street, IPT, CSL 100, University of Southern California, Los Angeles, CA 90033, USA.

E-mail address: [email protected] (K. Inaba).

amputations [3]. In the pre-hospital setting, this can be a critical, time sensitive technique used to free a patient who is entrapped. For victims of an industrial accident or motor vehicle collision that cannot be extri- cated, field amputation may be life-saving [4-6]. Under these austere conditions, the procedure must be performed as rapidly as possible, often in a confined space, while minimizing risk to the care provider.

Because of its efficiency, simplicity, light weight and portability, the

Gigli saw is one of the most widely used saws in the pre-hospital phase of care [7,8]. There are no external electrical power requirements and it is readily available for performing an amputation. However, with ad- vances in portable battery technology, several other options are now available. There is however, a paucity of literature supporting the choice of one saw type over another for this purpose.

https://doi.org/10.1016/j.ajem.2021.02.034

0735-6757/(C) 2021

Phase 2 – saw characteristics and”>McNicholas et al. [9] compared a “bone saw”, not further specified in the study design, against a fire service hydraulic cutter designed to cut through steel or the sub-frame of a motor vehicle. This experiment con- firmed that hydraulic equipment can provide a faster amputation at the cost of a lower quality bone cut, but the practical utility of using this type of machinery is not known. In addition, the hydraulic cutter is bulky and can weigh upwards of 20 kg, requires special protective equipment and specialized training for safe use. Leech et al. [10] compared four tech- niques of cadaveric lower limb emergency amputation. In this study the amputations were conducted with a Gigli saw, a hacksaw, a recipro- cating saw and a Holmatro device, which is also a hydraulic cutting in- strument. Amputation was completed using all techniques in less than 91 s. While there may have been differences in the quality of skin, soft tissue and bone cuts, the validity of this study was limited because only four amputations, one per device, at one amputation site was per- formed. In addition, for some devices, both soft tissue and bone were cut, while for others, only bone was evaluated. A recently published study [11] compared a Gigli saw with a hacksaw and a Reciprocating saw on porcine legs. The authors concluded that the hacksaw or recipro- cating saw may result in faster Amputation times with fewer Instrument malfunctions compared to the Gigli saw. The primary limitation of this study was that all amputations were performed on porcine legs. The clinical translation of this data to an emergent human bone amputation is not known.

The ideal saw and optimal approach, i.e., through bone or joint, for a field amputation procedure remains controversial and was the aim of this study.

1. Material and methods
   1. Setting and design

Institutional Review Board approval was obtained from the Univer- sity of Southern California. This prospective cadaver-based study was conducted in the Fresh Tissue Dissection Laboratory of the LAC+USC Medical Center between April and September 2019. The study was con- ducted in four phases: 1) saw and blade selection 2) saw characteristics and ergonomics 3) through bone amputations 4) through joint amputations.

• • 1. Phase 1 – saw and blade selection”>Phase 1 – saw and blade selection

In phase one of the study we sought to identify candidate saws that could be evaluated for use in the field. The following criteria were con- sidered for saw selection: Ease and efficiency of sawing, simple and safe handling, size and portability. Using these selection criteria, we identi- fied four major saw types (Gigli, manual pruning, electric oscillating and electric reciprocating). The skin and soft tissue of six unfixed adult porcine upper extremity limbs were removed to expose the bone of the carpus and metacarpus. Multiple amputations were performed with each saw in order to evaluate the ability of each saw and blade to cut through bone. For each of the electric saws where blades can be interchanged, a selection of blades were tested to determine which blade type would most effectively cut through bone. The total time re- quired to cut through bone was utilized as the criteria for final blade selection.

The standard Gigli, Medline(R) (Rialto, CA, USA) was evaluated with wire lengths of 25, 50 and 75 cm. The manual pruning saw, Fiskars Power Tooth Pruning Saw(R) (Middleton, WI, USA) was tested with a 7? (17.8 cm), 10? (25 cm) and 18? inch (45 cm) blade, all with triple- ground teeth. The oscillating saw, DeWalt DC S355 20 V XR(R) (Balti- more, MD, USA) was evaluated with the following blade types, lengths and widths (BOSCH Wood/Metal 2.5?, DeWalt BI-METAL, DREMEL UNI- VERSAL PIPE & 2 x 4 BLADE, IMPERIAL BLADES, SPEARTOOTH, 2.5?

64 mm). For the reciprocating saw, DeWalt 20 V MAX(R) (Baltimore, MD, USA) two different 9-in. blades were compared (DIABOLO METAL DEMOLITION(R) 8/10 Teeth Per Inch and a METAL 3/17 Teeth Per Inch).

• • 1. Phase 2 – saw characteristics and ergonomics

We examined the saw characteristics and practical ergonomics of each device for use in a confined space. The size and weight of each saw was measured including the blades and batteries. We then deter- mined the physical space required to perform an amputation for each saw. During the through femur amputation session of study phase 3 (through bone amputation), we measured the three-dimensional space each of the four saws occupied during the dynamic amputation process. For the Gigli saw, the space was calculated by measuring the maximum distance between the handles, the maximum distance from bone to the Gigli handle, and the physical width of the instrument used during the amputation process. For the remaining saws, the space was calculated by measuring the maximum height obtained by each saw, the maximum depth reached, and the physical width of the instrument used during an amputation without changing the angle of approach.

• • 1. Through bone and through joint amputations

In total, three unfixed adult cadavers were utilized for completion of study phase 3 and 4. All cadavers were inspected to exclude evidence of congenital, or development malformations. There was no evidence of external injuries to the extremities. The cadavers were kept in refriger- ated storage at +4 ?C. Two hours prior to the experiment, they were allowed to warm to Room temperature. Before the experiment, sex, race, age, weight, height and body mass index (BMI) of each cadaver was documented. They were then positioned supine with abducted arms on a standard operating room table. All cadaver amputations were recorded on high-speed video (Model Panasonic HC-W580, New- ark, NJ, USA) in order to allow review of the data. All procedures were performed by a general surgeon with a research coordinator as the assistant.

• • 1. Phase 3: through bone amputations

Each saw was tested for its ability to perform a through bone ampu- tation at each of four long bone sites: humerus, ulna/radius, femur and tibia/fibula. Two cadavers were utilized, providing a total of four ampu- tations per long bone site. For each site, the skin and Soft tissues were cut with a scalpel to expose the bone at a standardized position. The am- putation sites were defined as follows: 10 cm proximal to the olecranon for the humerus, 10 cm distal to the olecranon for the ulna/radius, 10 cm above the upper patella margin for the femur, 10 cm below the lower patella margin for the tibia/fibula. The limb and bone circumference of each amputation site was documented. In addition, the coefficient of the cross-sectional area of soft tissue vs bone was calculated as an aver- age value for the different amputation sites. The order of amputation oc- curred from distal to proximal (tibia/fibula before femur, then ulna/ radius before humerus). For each amputation site, the order of limb use and saw sequence were determined by computer randomization. A new saw blade was used for each amputation. The time required for each saw to cut through the bone, the number of attempts required to seat the saw to begin transecting the bone, slippage defined as move- ment of the saw from the bone during the cut, quality of proximal bone cut, proximal fracture propagation and extent of body fluid splat- ter including visual splatter on Personal protective equipment were re- corded. For the proximal fracture propagation and the quality of bone cut the proximal bone stump was visually assessed after the amputation was performed. Proximal fracture propagation was recorded in millime- ters. A visual grading system was utilized to score the quality of the proximal stump (Fig. 1). The area around the cadaver was examined for visible body fluid splatter. In order to quantify the extent of the splat- ter, a fresh sheet was placed under the amputation site before the pro- cedure. After each amputation was performed, we then measured from the amputation site to the furthest extent of splatter in a straight-line distance in cm and utilized this as the maximum extension of potential body fluid splatter. The splatter on the personal protective equipment of the surgeon who performed the amputations was graded

Fig. 1. Visual grading system to assess quality of the proximal stump. Good = smooth bone edge, no splintering, minimal damage; average = minor bone edge damage and splintering; poor = ragged bone edge, extensive splintering, significant damage.

as follows (clean = no splatters; local contamination = splatters on arms and/or abdomen; extensive contamination = splatters on chest and/or head/face).

• • 1. Phase 4: through joint amputations

The most effective saw in the through bone assessment (study phase 3) was selected for through joint amputations and compared to the technique using scalpel and scissors. A third cadaver was used to test four different through joint amputation sites (elbow, wrist, knee and ankle). A circumferential skin incision was performed with a scalpel at the level of the joint at each site prior to the amputation. Prior to the ex- periment, the joint circumference of each amputation site was docu- mented. The order of amputation occurred from distal to proximal (ankle, knee, wrist and elbow). For each amputation site, the technique utilized was determined by computer randomization. The time required for each joint amputation, and the quality of the cut were recorded.

• 1. Experimental measurements and statistical analysis

The following outcomes were compared between the different saw types: time required to cut through the bone or joint, number of at- tempts, slippage, quality of bone cut and extent of fluid splatter.

Data collection was performed using a computerized spreadsheet

(Microsoft Excel 2016; Microsoft Corporation; Redmond WA) and ana- lyzed using SPSS Statistics 23 (IBM Corporation; Armonk, NY). Results were reported as numbers and percentages or medians and interquar- tile ranges (IQR). Categorical variables were compared using Fisher’s exact test. Kruskal-Wallis or Mann-Whitney U test were used for analy- sis of continuous variables, as appropriate.

blades were selected: the 50 cm wire Gigli saw, the 10 in. (25 cm) blade for the manual pruning saw (Fiskars Power Tooth Pruning Saw(R)), the DREMEL(R) PIPE & 2 x 4 BLADE for the cordless oscillating saw (DeWalt DC S355 20 V XR(R)) and the 9 in. DIABOLO(R), 8/10 Teeth Per Inch blade for the reciprocating saw (DeWalt 20 V MAX(R)).

The Gigli saw (32 g) with a wire length of 50 cm required 4500 cm³ physical space to perform an amputation. The medium-weight pruning saw (327 g) with a 10-in. (25 cm) blade needed almost twice as much physical space (8000 cm³), while the electric oscillating saw at 1026 g required less, at 3500 cm³ to perform an amputation. The heavier elec- tric reciprocating saw (2369 g), equipped with the stable 9-in. DIABOLO(R) blade, required the most physical space to perform an am- putation (12,000 cm³). The saw characteristics including the physical space required to perform an amputation are summarized in Table 1.

• 1. Through bone and through joint amputations

A total of 16 through bone amputations on two cadavers and eight through joint amputations on a separate cadaver were performed. The two cadavers used for the through bone amputations (study phase 3) were both white females in the postmenopausal age group and had a similar height (170 vs 167 cm) and weight (79.0 vs 78.2 kg). The ca- daver used for the through joint amputations (study phase 4) was also a white female, age 67, with a height and weight of 161 cm and

56.0 kg. Cadaver characteristics are shown in Table 2.

• 1. Phase 3: through bone amputations

Table 3 summarizes the results of the through bone amputation. The average coefficient of the cross-sectional area of soft tissue vs bone was calculated for each of the four through bone amputation sites: 23.7 for the upper arm, 14.2 for the forearm, 19.6 for the thigh and 7.0 for the lower leg. Overall, the reciprocating saw was the fastest (2.1 [1.4-3.7] seconds), followed by the oscillating (3.0 [1.6-4.9] seconds) and the Gigli saw (5.6 [4.3-8.6] seconds). The pruning saw (58.8 [25-121] sec- onds) was the slowest (p = 0.007). The number of attempts required to amputate (5.8 [3.0-8.3], p = 0.02) and the amount of slippage (3.0 [1.5-3.8], p = 0.03) were highest with the pruning saw. The reciprocat- ing saw had the worst proximal bone cut quality (75% poor, p = 0.04) and the largest extent of blood splatter (47.5 [41-63] cm, p = 0.044).

• 1. Phase 4: through joint amputations

Table 4 summarizes the results of the through joint amputations. The overall amputation time between the two techniques were similar (125.0 [50-147] seconds for scalpel and scissor vs 125.5 [86-217] sec- onds for the oscillating saw, p = 1.00). Saw marks on the proximal

Table 1

Characteristics of the four selected saws optimized for a field amputation

	Gigli	Pruning	Oscillating	Reciprocating
Size (cm)	6.4 x 8	55.5 x 14 x 2.5	32.5 x 12 x 8	62 x 20 x 8
	(T-handle)
Weight (gram)a	50 (wire) 32	327	1026	2369
Physical space	Ca 4500	Ca 8000	Ca 3500	Ca 12,000

needed (cm³)^b

1. Results

Powered by electricity

no no yes yes

• 1. Phase 1 and 2 – saw and blade selection including saw characteristics and ergonomics

All four saw types (Gigli, manual pruning, electric oscillating and electric reciprocating) were tested on the pig model. The following

Specific saw models used: standard Gigli saw with a 50 cm wire, Fiskars Power Tooth Pruning Saw(R) with a 25 cm blade, DeWalt DC S355 20 V XR(R) oscillating saw equipped with a DREMEL(R) PIPE & 2 x 4 BLADE and a DeWalt 20 V MAX(R) reciprocating saw with a 9 in. DIABOLO(R), 8/10 Teeth Per Inch blade.

^a Indicated weight includes the blades and batteries for the electric saws.

^b Physical space was defined as the space occupied by each device during the dynamic process of the amputation.

Table 2

Cadaver characteristics for through bone and joint amputations

Table 4

Results of the through joint amputations

	Cadaver 1	Cadaver 2	Cadaver 3			Scalpel and Scissors	Oscillating saw
Gender	female	female	female		Time (sec)
Ethnicity	white	white	white		Elbow	147.0	148.0
Age	postmenopausal	postmenopausal	67 years		Wrist	32.0	103.0
Height (cm)	170	167	161		Knee	103.0	240.0
Weight (kg)	79.0	78.2	56.0		Ankle	147.0	80.0
BMI (kg/m2)	36.7	36.6	21.6		Overall	125.0 (50–147)	125.5 (86–217)
Humerus circumference (cm)	6.2/5.9	6.0/6.0
Elbow circumference (cm)			22.0/22.0

bone amputations with the Gigli and reciprocating saw were signifi- cantly faster than the through joint amputation using the oscillating

Radius circumference (cm)	4.6/4.5	4.9/4.3
Ulna circumference (cm)	4.2/4.5	4.6/4.4
Wrist (cm)	15.0/15.5

Femur circumference (cm)	9.7/10.6	9.8/9.5		saw (5.6 [4.3-8.6] seconds vs 125.5 [86-217] seconds, p = 0.029 and 2.1 [1.4-3.7] seconds vs 125.5 [86-217] seconds, p = 0.029). The
Knee circumference (cm)			31.0/34.0	through bone amputations with the Gigli saw (5.6 [4.3-8.6] seconds),
Tibia circumference (cm)	11.5/12.3	10.4/10.9		the oscillating saw (3.0 [1.6-4.9] seconds) and the reciprocating saw
Fibula circumference (cm) Ankle (cm)	3.4/4.1	3.9/4.0	21.5/21.0	(2.1 [1.4-3.7] seconds) were also performed faster than the through joint amputations using scalpel and scissors for all comparisons (125.0

Through bone amputations were performed on cadaver 1 and 2, amputations through joints on cadaver 3. All circumferences were measured in cm at a standardized level. The right/left side is shown for all cadavers.

Table 3

Results of the through bone amputations according to the saw used

	Gigli	Pruning	Oscillating	Reciprocating	p value
Time (sec) Humerus	4.8	52.7	1.8	1.4	0.007
Ulna/radius	4.2	65.0	1.6	1.4
Femur	9.3	15.8	4.2	4.0
Tibia/fibula	6.5	140.0	5.1	2.9
Overall	5.6 (4.3–8.6)	58.8 (25–121)	3.0 (1.6–4.9)	2.1 (1.4–3.7)
Number of attempts	1	5.8 (3.0-8.3)	1	1	0.002
Slippage	0	3.0 (1.5-3.8)	0	1.0 (1.0-1.8)	0.003
Proximal bone cut
quality Good	3 (75%)	1 (25%)	4 (100%)	0 (0%)	0.04
Average	1 (25%)	1 (25%)	0 (0%)	1 (25%)
Poor	0 (0%)	2 (50%)	0 (0%)	3 (75%)
Proximal fracture propagation (mm)	0 (0.0-2.1)	0.7 (0.0-3.7)	0	1.4 (0.3-2.7)	0.236
Extent of splatter (cm)	46.5 (32-72)	28.5 (26-36)	37.0 (31-40)	47.5 (41-63)	0.044
Visual Splatter PPE Clean	1 (25%)	1 (25%)	2 (50%)	0 (0%)	0.301
Local contamination	2 (50%)	3 (75%)	2 (50%)	1 (25%)
Extensive contamination	1 (25%)	0 (25%)	0 (0%)	3 (75%)

The amputation time is shown for each amputation site and used saw, the remaining values are displayed as median or % values of all amputations performed according to the saw used. Abbreviations: PPE, Personal protective equipment. Significance of bold: p < 0.05

joint surfaces were detected after every run with the oscillating saw. The left elbow joint was partially missed during amputation with the oscillating saw resulting in a with partial resection of proximal ulna.

Overall, the oscillating saw performed the through bone amputa- tions significant faster than the through joint amputations (3.0 [1.6-4.9] seconds vs 125.5 [86-217] seconds, p = 0.029). The through

[50-147] seconds, p = 0.029).

1. Discussion

Field amputation can be a life-saving procedure for entrapped pa- tients requiring surgical extrication. Rapid extrication and transport of the casualty to a trauma center improves their chances for survival [12,13]. Performing an amputation in the field elevates both patient and provider risk dramatically and anything that can be done to im- prove the safety and efficacy of this procedure should be implemented to mitigate risk.

The Gigli saw may be considered the default standard for field am- putation. As seen in our evaluation, this saw is inexpensive and readily available for performing an amputation, easy to store, and there are no power requirements. However, when utilizing a Gigli saw, the wire has to be placed around the amputation site before initiating the sawing process. More importantly, in a confined space, achieving the correct operator positioning to perform the amputation may be impossible. The oscillating saw used in this study was superior or equivalent to the Gigli saw in every aspect tested, except for size and weight. It is ex- tremely fast with precision handling and minimal operator space re- quirements. The highly adjustable blade makes this saw ideal for a field amputation in confined spaces. The characteristics of the oscillating saw, specifically the relatively light weight, precise handling and the ad- justable blade angle, allow for a very flexible range of use including the option of one-handed operation. As operative space becomes limited, these attributes may mean the difference between success and failure. Although the integrated light available on the saw model used in this study cannot rotate fully with the blade, it remains a major advantage if a field amputation has to be performed under low light conditions. In comparison to the oscillating saw, the reciprocating saw utilized in this study required direct access to the amputation site and sufficient space to correctly position the saw for the procedure. In addition, one- handed operation of this heavy and bulky tool is not practical because the blade cannot be adequately controlled and the pressure of the blade against the bone required to perform the amputation cannot be maintained with one hand. Amputations completed with the manual pruning saw had ergonomic restrictions mandating free access to both sides (and ideally the space underneath) the amputation site in order to enable the dynamic sawing process. Additionally, the saw operator requires sufficient space in order to complete the full sawing range of motion. These major limitations paired with extended amputation times preclude its use for field amputation.

The extent of body fluid splatter encountered while performing a

field amputation is an important aspect of safety criteria [14]. The risk

of contamination for care providers increases with the quantity and ex- tent of splatter during the amputation process. The furthest extent of splatter measured in a straight-line distance from the amputation site correlated with the extent of splatter detected on the personal protec- tive equipment. When using the Gigli saw, the sawing direction and therefore the splatter, is inevitably directed toward the saw operator. The contamination was particularly noticeable at the moment of com- plete bone transection upon the sudden loss of resistance. In compari- son, the fast and relatively wide movements of the reciprocating saw blade resulted in a very large extent of splatter with constant direction- ality. This increased contamination risk associated with the use of a re- ciprocating saw is in agreement with the study published by Leech et al. [10]. Both, the oscillating saw and the pruning saw were associated with minimal contamination and represented an acceptable risk for care pro- viders wearing Personal protective equipment . In order to miti- gate this risk, and for Hemorrhage control, a tourniquet will be placed prior to amputation [15-18], but even then, decreasing splatter is of crit- ical importance.

The level of a field amputation is dictated by both the clinical situa- tion and the environment in which the patient is trapped. In general, the amputation is performed as distally as possible to preserve tissue. A through joint amputation may be required, however, this study dem- onstrated several practical anatomical challenges to such an approach. The ligaments and cartilaginous structures made it difficult to identify the joint space and prolonged the amputation time. The through joint amputations were also significantly slower than the through bone am- putations. If time is a critical factor, a through bone amputation may be superior.

All amputation procedures were performed under optimal experi- mental conditions by an experienced general surgeon assisted by a re- search coordinator. All cadavers were placed on a standard operating room table with ideal lighting, providing open access to the amputation specimen. Additionally, for standardization at all amputation sites, the skin was pre-cut to expose the bones or the joints. These conditions likely explain the faster amputation times of the tested saws compared to previous studies [9,10]. The real-life conditions under which field am- putation actually occurs are never ideal. Complex situations with an entrapped limb, limited space or lighting conditions, and minimal or no experience with amputation procedures may further limit the per- formance of these saws.

The skin was cut with a scalpel prior to sawing in this study in order to focus the evaluation on bone transection. While pre-amputation skin incisions may not be necessary, there are several tangible benefits to both the patient and the prehospital provider completing the amputa- tion. Sawing directly through the skin without first incising the skin and soft tissues can cause unnecessary damage to the soft tissues. Iatro- genic soft tissue destruction may require additional surgical revision and increase the possibility of a surgical site infection which would neg- atively impact limb length preservation. The use of a scalpel prior to sawing may also limit blood splatter, thus mitigating the risk of biohaz- ardous exposure to all of the nearby Prehospital personnel.

This was an extensive human evaluation designated to identify the optimal saw and approach, through bone or joint, for a field amputation. Different amputation levels, including through joint amputations were tested with various saws optimized in advance for this purpose. All amputations were performed by a single surgeon to avoid inter- personal differences in sawing abilities. However, there may be provider-specific differences in techniques, and experience that could not be captured by the study design. In addition, the field amputation may be performed by a prehospital care provider rather than a surgeon, with varying differences in efficacy. The extent of splatter was evaluated in non-perfused cadavers. While the low residual blood volume in the cadaveric vasculature did not allow for an estimation of hemorrhage during the amputation procedures, practically, the extent of splatter would be expected to be even greater for a living human extremity. The differences are still meaningful as this was held constant

throughout all of the test runs. Furthermore, the exact age of the two fe- male cadavers on which the through bone amputations were performed was not available. Because they were postmenopausal, their bone den- sity may be lower than the younger patient population. Finally, the out- comes and specific saw characteristics are based on the models used and the outcomes may differ if a different saw model or manufacturer is utilized.

1. Conclusion

The speed, precision, safety, space required, as well as the adjustable blade of the oscillating saw utilized make it ideal for a field amputation. A Gigli saw is an excellent backup for when electrical tools cannot be used. Through bone amputation is faster than through joint amputation and may be preferred.

Funding

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.

Grant support

None.

Statement of human rights

The study was approved by the Institutional Review Board of the University of Southern California.

Credit author statement

DAJ, MM, KI designed the study. DAJ and MM carried out the mea- surements. DAJ analyzed data. DAJ and KI wrote the first draft of the manuscript. All authors contributed to the interpretation of the data and writing of the manuscript, and approved the final version of the manuscript. KI supervised all aspects of study design, analyses, and manuscript writing.

Declaration of Competing Interest

All authors declare no potential conflict of interest.

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