Occup. Med. \to). 49, No. 1, pp. 17-26, 1999Copyright O 1999 Upplncott Wlfflams & Wllktns for SOM

Printed In Great Britain. All rights reserved0962-7480/99

Military parachuting injuries: aliterature reviewM. C. M. Bricknell* and S. C. Craig**Army Medical Directorate, Keogh Barracks, Aldershot, Hants,GUI 2 5RR, UK; +Epidemiology Programs, Directorate of Epidemiologyand Disease Surveillance, USACHPPM, Aberdeen Proving Ground,Maryland 21010, USA

This article is a literature review of the aspects of military parachuting related tooccupational medicine and focuses on 'conventional' military static line parachutingusing a round parachute. The analysis of injuries resulting from military parachutingprovide an excellent example of military occupational medicine practice. Thetechniques of military parachuting are described in order to illustrate the potentialmechanisms of injury, and a number of 'classical' parachuting Injuries are described.Rnally some recommendations are made for the recording of parachute injuries whichwould assist in the international comparison of injury rates and anatomical distribution.

Key words: Military; occupational health; parachuting.

Occup. Med. Vol. 49, 17-26, 1999

Received 26 January 1998; accepted in final form 18 Junt 1998

INTRODUCTION

The development of military parachuting techniqueswhich have allowed large numbers of soldiers to be deliv-ered to the battlefield by air provides an example of howphysicians have been closely involved with a workforceoperating in a hazardous environment. This relationshiphas led to the definition of a health and safety policy; thecreation of medical standards for employees; refinementof workplace equipment and procedures; the provisionof a medical service; the measurement of performancewith effective audit and the publication of numerous aca-demic papers. The medical support of military parachut-ing is an excellent example of the practice of militaryoccupational medicine.

This review focuses on 'conventional' military staticline parachuting using a round parachute. It excludes theuse of square parachutes which, for military use, isalmost invariably the province of small teams of special-ist soldiers. The over-riding requirement in military para-chuting is to have a system which enables soldiers tojump from an aircraft and land on the ground in a fitstate to fight. The parachute system should enable theaircraft to fly as low as possible to enable it to avoid radarand anti-aircraft weapons systems. The soldiers shouldexit the aircraft as fast as possible to minimize the timethe aircraft spends over the dropping zone (DZ) and alsoto reduce the dispersal of soldiers across the DZ. The

Correspondence and reprint requests to: M. C. M. Bricknell, 53 AlbanyRoad, Fleet, Hants GU13 9PU, UK. Tel (+44) 01252 624389.

design of the parachute should allow the soldier to para-chute with sufficient personal equipment to be effectiveand it should be released as soon as possible after arrivalon the ground so that the soldier can get into actionquickly. Such an operation would be likely to be con-ducted at night.

The technique of military parachuting

The principles of operation of the military parachutehave remained essentially unchanged since the 1940s butseveral modifications have improved its performance andsafety record. The military parachute is contained in abag on the back of the soldier. The soldier almost invaria-bly will have a reserve parachute attached to his front. Ifmilitary equipment is carried, it is usually attached belowthe reserve parachute.

The parachute is opened by a 'static' line attached to astrong point on the aircraft. Parachutists exit from theside door of the aircraft, either singly and in rapid suc-cession or from alternate sides of the aircraft in rapidsuccession. As the parachutist falls the static line pulls theparachute and rigging lines from the bag until the systemhas completely deployed. At this point the breakingstrain of the tie holding the static line to the parachute isexceeded, the static line breaks off and the parachutistfalls free as shown in Figure 1. If the parachutist is carry-ing equipment this is often lowered on the end of a ropeduring descent so that the parachutist hits the groundunencumbered. The landing force varies between typesof parachute but is usually equivalent to jumping off a

18 Occup. Med. Vol. 49, 1999

Figure 1. A military parachutist. Figure 2. The parachute landing roll.

I

9-12 foot wall. The kinetic energy is dissipated by a land-ing roll.

During the early days of parachute training the Ger-mans and the Americans taught a forward landing roll.Trainees landed with feet apart and conducted a forwardroll across an outstretched arm. The German parachuteharness was attached at a single point at the centre of theupper back and consequently the parachutist landed in aforward facing position making this type of landing rollthe only option. The US harness was similar to the Brit-ish harness with the rigging lines merging onto riserswhich attached to the parachute harness on the top ofeach shoulder. Thus the parachutist descended in anupright position. The British developed an alternativelanding roll in which the parachutist landed with trie feetand knees together and conducted a sideways roll suc-cessively onto outer side of the leg, thigh, buttocks,across the back and onto the opposite shoulder. Thistechnique caused significantly fewer injuries than thefirst forward landing roll and was adopted by the USArmy in June 1943.' The parachute landing fall (PLF) isshown in Figure 2.

It is possible for the wind to catch the parachute afterlanding and drag the parachutist along the ground, thuscausing injury. In order to prevent this the parachute is

collapsed as quickly as possible, either by pulling on therigging lines which causes air to spill from the canopy, orreleasing a riser from the harness using a speciallydesigned release catch. Once this is done the parachutistremoves the harness and is ready for action.

Training and selecting military parachutists

The military parachutist is regarded as part of an eliteelement in all the armed forces. Appointment to the roleis usually the result of a selection process that tests phys-ical fitness and mental determination. The rationalebehind this has more to do with the nature of airborneoperations than the requirement for high standards ofphysical fitness for parachuting per se. Once a soldier hasqualified as a military parachutist in the British airborneforces the basic fitness standards are no different fromthe remainder of the British Army. There is internationalvariation in the military physical standards required forparachuting and in many countries women are allowedto parachute if they achieve the physical standardsrequired.

The training for military parachutists is considerablylonger than that required for civilian parachutists. This isbecause the practical skills required are substantiallygreater, eventually leading to the ability to conduct amassed parachute assault at night. This training has thedesired effect of imprinting the biomechanical skillsinvolved so that the basic drills become automatic. This

M. C. M. Bricknel and S. C. Craig: Military parachuting Injuries 19

principally applies to conditioning the response of exit-ing the aeroplane on the 'Green light' or command 'Go'and the proper execution of the PLF.

PARACHUTING INJURY RATES

The aim of this review was to produce a 'benchmark' forparachuting injury rates from a review of the medicalliterature. A systematic search was made of the medicalliterature using Medline to search Index Medicus back to1963 for reports of medical aspects of parachuting. TheMesh terms used were 'parachuting' and 'aviation'. IndexMedicus was also hand-searched for reports dating from1940-63. The Journal of the Royal Army Medical Corpsand Military Medicine were hand-searched for paperspublished prior to 1963. Only English language publica-tions were obtained because there was no facility fortranslation. The reference list for each paper was alsochecked to obtain further reports.

Each paper was reviewed to obtain injury rates. Paperswere included in the analysis if there was a clear casedefinition, a clear description of the setting and the ratedenominator was based on parachute descents. Studieswere excluded if it was clear that not all parachute inju-ries were included (e.g., studies based on positive x-rayfindings) or if the denominator was based on time (e.g.,annual incidence) rather than descents.

Table 1 shows all reported rates of injury for militaryparachuting per thousand descents. Rates for single par-achute programmes were excluded because these reportsmay cover extreme casualty rates. All reports chosenshow a mean of injury rates measured over at least a 6month period. The summary statistics exclude the USand UK reports from the Second World War becauseboth report rates approximately ten times greater than allsubsequent reports.

Table 2 shows a summary of the reported injury ratesfor civilian parachuting. Unfortunately, only threereports could be found. It should be noted that a sub-stantial proportion of civilian parachuting included free-fall parachuting in which the parachutist deploys his ownparachute. This affects the injury pattern, obviating staticline injuries but creating the risk of injury during thefreefall period. A study by Ellitsgaard17 reported fiveinjuries occurring during freefall of which four werefatalities.

There are many factors reported that affect the casu-alty rates for individual parachute programmes, a num-ber of which are listed in Table 3. The associationbetween ground wind speed and casualty rates was real-ized very early on in the development of military para-chuting. Early British experience suggested a markedincrease in casualty rates at wind speeds greater than 15mph (13 knots),3 and a more recent analysis11 suggesteda cut-off point at 9 knots. A Belgian report suggested acut-off point at 12.75 knots.9 It is clear that casualty ratesincrease with increasing windspeed and thus many mili-tary forces have a windspeed threshold for parachuting.The height and weight of the parachutist also has aneffect on injury rates. Several studies have shown that the

mean weight of casualties amongst military parachutistsis greater than the mean weight of the military parachut-ing population as a whole.9'11>13 The evidence for anassociation of risk of injury with increasing height is lessclear with an English study demonstrating a linear corre-lation11 but a Belgian study failing to show any rela-tionship.9

ANATOMICAL DISTRIBUTION OFPARACHUTING INJURIES

There is a well-recognized constellation of injuries asso-ciated with a fall from a height, which reflects the dis-tribution of kinetic energy along the body. Table 4 is asummary of the anatomical distribution of injuriesreported from military parachuting. It is not appropriateto summarize the anatomical distribution by taking amean of the reported injury rate for each region becauseof the variation in reporting criteria and diagnostic cate-gories used by different authors. However, it can be seenthat most injuries occur to the ankle with a progressivelylower proportion affecting the leg, back, arm, shoulderand chest Closed head injuries represent a significantproportion of injuries, which reflects the vulnerability ofthe brain to impact.

The mechanisms of parachuting injuries

Parachute injuries can occur at any time between leavingthe aircraft and completing the removal of the harness.These are best grouped as problems with exit, descentand landing. Bizarre incidents, such as a reserve para-chute opening within the aircraft, will be excluded fromthis discussion.

The static line is usually attached to a cable runningthe length of the aircraft. This enables the parachutist'sstatic line to move down the aircraft with him until it is inline with the door as he exits. Initial parachute exit train-ing required the parachutist to grasp both sides of thedoor. This created a gap between the parachutist and hisoutstretched arms in which, occasionally, the static linebecame trapped. This could lead to injury to the upperarm or shoulder.23 The exit procedure used by UKforces has always emphasized a tight exit with the handsclasped onto the equipment. The US airborne forcesadopted this technique in March 1994 by holding ontothe reserve which has led to a substantial reduction inthis mechanism of injury for their airborne forces.

Parachutists are taught to look up and make a positive'drive' out of the door on exit, thereby ensuring a goodposition. If the parachute fails to deploy properly afterexiting the aircraft, parachutists are trained to operatetheir reserve. If the parachutist exits in an uncontrolledmanner he may tumble or twist which can lead to prob-lems with the deployment of the parachute or rigginglines. In severe cases this can cause entanglement whichmay affect the deployment of the main parachute or theparachutist's ability to take up a safe landing position. Ifhe falls with his legs above his head then his legs can becaught as the rigging lines deploy — an accident which

Tab

le 1

A.

Rep

orte

d in

jury

rat

es f

or m

ilita

ry p

arac

hutin

g (In

jurie

s pe

r th

ousa

nd d

esce

nts)

Ref 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Pub

licat

ion

year

1941

1946

1946

1951

1965

1960

1975

1985

1989

1991

1992

1995

1996

1997

1998

Cou

ntry

US

AU

K

UK

US

A

US

A

US

A

Isra

el

Bel

gium

UK

UK

Aus

tral

ia

Mal

aysi

aU

SA

US

A

Isra

el

Yea

r of

stud

y

Aug

194

0-A

ug 1

941

Jan-

Nov

194

4

Apr

194

2^Ja

n 19

43Ja

n 19

44-O

un 1

945

1946

1947

1948

1949

1946

1947

1948

1949

1956

1957

1958

1959

1960

1961

1962

1962

1963

1956

1957

1958

1959

1974

-198

3

n/k

1983

-86

Mar

198

7-O

ec 1

988

n/k

n/k

1993

1994

1995

n/k

Cru

de r

ates

(pe

rth

ousa

nd d

esce

nts)

No

ofJu

mps

4490

2077

7

1069

666

408

2100

439

662

3284

880

706

2100

439

662

3284

880

706

6164

989

325

9778

510

7127

9528

110

1226

8341

295

099

1155

1861

649

8932

597

785

1071

2783

718

2019

77

5182

834

236

8886

9514

7948

1381

3210

7115

1338

8843

542

Inju

ryra

te

24 21 37 2.6

6.5

7.6

6.4

4.2

6.5

7.6

6.4

4.2

4.5

2.1

4.3

4.7

3.4

2.4

2.3

0.9

1.4

4.5

2.1

4.3

4.7

6.26

5 4 11.1 7.1

3.8

227.

18.

97.

58.

9

Day

Jum

ps fr

om

Day

Jum

ps f

rom

baB

oon,

with

out

ballo

on,

with

equi

pmen

t eq

uipm

ent

No

ofJu

mps

810

1493

3433

2

3752

5

7120

Inju

ry

No

of

Inju

ryra

te

Jum

ps

rate

11 24 0.17

21

150

0.33

1.41

0.13

Day

Jum

ps f

rom

airc

raft,

with

out

equi

pmen

t

No

ofJu

mps

1327

2

2121

5

2107

3

1353

5687

Inju

ryra

te

1.7

0.52

1.9

1.5

3.3

Day

jum

ps

from

airc

raft,

with

equi

pmen

t

No

ofju

mps

1783

1

9203 779

2342

3

2374

0

3199

3211

Inju

ryra

te

19 412.

7

4.62

0.85

15.3

13.7

14

Nig

ht J

umps

fro

mai

rcra

ft, w

itheq

uipm

ent

No

ofJu

mps

2136

9948

2116

4358

Inju

ryra

te

14 11.2

5

0.7

1.37

27

Inju

ry c

lass

ifica

tion

Inju

ry •=

rec

eipt

of

med

ical

trea

tmen

t on

DZ

n/k

not

give

n

Inju

ry «

Inci

de

nt

caus

ing

time

lost

fro

m d

uty

Inju

ry =

rece

ipt

of m

edic

altr

eatm

ent

on D

ZIn

jury

= fr

actu

re,

first

sho

ulde

rdi

sloc

atio

n, a

dmis

sion

<

1

day

Inju

ry =

see

n at

A+E

Inju

ry =

eve

nt r

equi

ring

trea

tmen

ton

DZ

Inju

ry •

req

uirin

g ev

acua

tion

from

DZ

, re

stric

tion

of d

utie

s o

rad

mis

sion

Inju

ry =

mod

erat

e/se

vere

Inju

ry =

any

res

tric

tion

of d

uty

Inju

ry «

ER

con

sulta

tion

82nd

AB

Dfv

Inju

ry =

Inci

dent

pre

vent

ing

jum

ps

for

at l

east

2 d

ays

Rem

arks

PLF

was

by

fwd

roll

6th

AB

Dfv

1st

AB

Dlv

672

typ

e of

para

chut

e66

5 ty

pe o

fpa

rach

ute

Par

achu

te t

rain

ing

US

Ran

gers

82nd

AB

Dlv

82

nd

AB

Dlv

Par

achu

te t

rain

ing

Tabl

e 1B

. S

umm

ary

stat

istic

s (e

xclu

ding

ref

eren

ces

4 &

5)

Cru

de r

ates

No

of j

umps

Tot

alM

ean

rate

Max

Mln

SD

95%

CI

5%C

I

Inju

ry r

ate

2437

940 5.

6122

.00

0.90

3.78

6.77

4.90

Day

jum

ps

from

bal

loon

,w

ithou

t eq

uipm

ent

Inju

ryra

te

7897

7 0.57

1.41

0.13

0.73

0.79

0.49

Day

jum

ps f

rom

bal

loon

,w

ith e

quip

men

t

Inju

ryra

te

2115

0 0.33

0.33

0.33

Day

jum

ps

from

airc

raft,

with

out

equi

pmen

t

Inju

ryra

te

6260

0 1.78

3.30

0.52

1.00

2.09

1.56

Day

jum

ps

from

airc

raft,

with

eq

uipm

ent

Inju

ryra

te

5435

2 8.53

15.3

00.

856.

4910

.52

7.42

Nig

ht j

umps

fr

om a

ircra

ft.w

ith

equi

pmen

t

Inju

ryra

te

1642

2 10.0

827

.00

0.70

12.2

713

.84

8.62

Tabl

e 2A

. R

epor

ted

inju

ry r

ates

for

civ

ilian

par

achu

ting

Onj

urie

s pe

r th

ousa

nd d

esce

nts)

Ref

Pub

licat

ion

year

Cou

ntry

Y

ear

of s

tudy

Cru

de r

ates

Day

jum

ps f

rom

Day

jum

ps

from

D

ay ju

mps

fr

om

Day

jum

ps

from

N

ight

jum

psba

lloon

, w

ithou

t ba

lloon

, w

ith

airc

raft,

with

out

airc

raft,

with

fr

om

airc

raft,

equi

pmen

t eq

uipm

ent

equi

pmen

t eq

uipm

ent

with

eq

uipm

ent

Inju

ry

clas

sific

atio

nRe

mand

s

17 18 19

1987

1986

1988

Den

mar

k

UK

Net

herla

nds

1979

-83

1984

1981

-85

1100

00

1935

647

278

6.7

2.7

3.7

110000

19356

4727

8

6.7

2.7

3.7

Inju

ry =

requ

irem

ent

for

Civ

ilian

med

ical

tre

atm

ent

Inju

ries

seen

at

A+

E d

ep

t C

ivili

an

Tabl

e 2B

. S

umm

ary

stat

istic

s

Tot

alM

ean

rate

Max

Min

SD

95%

CI

1766

34 4.3

6.7

2.7

2.08

5.00

2.84

22 Occup. Med. Vol. 49, 1999

Table 3. Associations with parachuting injuries

Factor Effect on injury rate

Wlndspeed Increasing windspeed increase rateMultiple parachutists leaving Increase

aircraftIncreaseIncreaseHard, uneven or hazards increase

rateDecrease relative to aircraftDecreased with modern parachutesIncrease

Night descentCarriage of equipmentNature of dropping zone

Balloon descentsDesign of parachuteHeight and weight of

parachutistInexperience of parachutist Increase

has been shown to be associated with damage to the col-lateral ligaments of the knee.24

The principal hazard during the descent phase is otherparachutists. It is possible to steer military parachutes alittle by pulling on the risers on the left or right andallowing some air to spill out. This is sufficient tomanoeuvre the parachute. Collisions with other para-chutists can cause entanglements with consequent risk tothe canopy. If a parachutist drifts over the top of anotherparachutist's canopy a phenomenon know as an 'air steal'can occur. In this case the bottom canopy 'steals' airfrom the top canopy which collapses. The top parachut-ist then free-falls until he is on the bottom at which pointhis canopy catches air which in turn steals air from theother canopy. Clearly if this happens close to the groundone of the parachutists can land without the support of afully deployed canopy.

It is impact with the ground that causes the majority ofmilitary parachuting injuries. In preparation for landing,the parachutist is trained to adopt a relaxed position. Thechin is placed on the chest and the hands clasp the liftwebs with the elbows tightly tucked in. The legs are heldforwards with the knees slightly bent and the toes liftedso that the feet land flat on the ground.

When the parachutist hits the ground he is subjectedto a number of forces as shown in Figure 3. These arethe downward force from gravity, sideways force fromwind, sideways force from oscillation and possibly a rota-tional force if he is spinning. The downward force isdependent on the parachute design and load. Factorsthat affect this are limits to the weight and volume ofparachute material that the parachutist can carry, themaximum design load for a parachutist and his equip-ment and the maximum descent speed consistent withlanding safely. The sideways force from the wind is acrucial factor that determines injury rate which hasalready been discussed. Oscillation of the parachute wasa significant problem with the early, semicircular designof parachute. This was reduced by removing a circle ofmaterial from the apex of the parachute so that air couldvent from the top and was not forced out from the edgeof the parachute in a uneven fashion. A mesh skirt wasdeveloped during the 1950s5 which is attached to theperiphery of the parachute to even the flow of air from

Figure 3. Diagram of forces on landing.

GRAVITY

WIND

OSCILLATION

the edge. Modern circular military parachutes are para-bolic in shape rather than semicircular which furtherreduces oscillation.12 The parachutist is taught to steerinto the wind during the last phase of descent in order toreduce the lateral velocity to a minimum. Spinning isusually the result of the untwisting of twisted rigginglines and is not normally a significant problem.

The feet should be the first point of contact with theground. If the toes are pointed the landing force is trans-mitted through the metatarsals (which may fracture) tothe articular surface of the tibia, possibly causing theposterior lip to fracture.25 If the landing is made with thefeet apart, one foot is likely to strike the ground beforethe other. When a paratrooper attempts a PLF, the anklefurthest from the direction of the PLF is subjected to aneversion force which may lead to a fracture of the ankle.If there is substantial sideways drift, even if the feet areheld tightly together, there is likely to be considerableforce acting on the ankle closest to the direction of thePLF which causes marked supination. This may causedamage to the ankle ligament complex, fracture of thetibia or fracture of the tibia and fibula.26 Strain of thesuperior tibio-fibular joint or fracture of the upper thirdof the fibula have been reported as classical parachuteinjuries, but are not often seen.1 Likewise, isolated kneeinjuries do not seem to be a common result of poorlandings.24

Severe landings due to parachute mishaps may causefractures of the femur or pelvis but the force required forthis is so great that it is unlikely that the unfortunateparachutist could have influenced the outcome. Landingbackwards can cause the parachutist to 'sit down' thus

M. C. M. Brtcknel and S. C. Craig: Mlitary parachuting injuries 23

Table 4. Regional distribution of parachuting Injuries (as percent of total reports)

Site of injury

Head and NeckClosed head injuryClosed HI with LOCClosed HI without LOCFacial contusionSkull/facial fractureMandible fractureNose fracture

Neck injuryNeck contusionNeck strain

ShoulderShoulder InjuryShoulder contusionShoulder sprainShoulder fractureShoulder fracture-dislocationShoulder dislocationAcromloclavicular dislocationFracture clavicleFracture scapula

ArmArm contusionStrain/sprainUpper extremity fracture/dislocationHumerus fractureElbow sprainForearm fractureUlna fractureFtadius fractureHand and wrist fractureWrist dislocationFinger dislocation

Chest and abdomenChest or abdominal wall injuryChest contusionSternum fractureRib fractureAbdomen contusionGroin contusionPelvic fractureSeparation of symphysls pubis

BackBack injuryBack contusionButtock contusionBack strainLumbrosacral sprainSacro-iliac sprainBack fractureBack fracture-dislocationContusion or fracture of coccyx

LegLeg strainContusion of legContusion of thighHip contusionHip sprainHip dislocationFemur fractureKnee contusionKnee sprainTear of collateral knee ligamentKnee meniscus injuryKnee dislocationPatella fractureTibia fractureFibula fractureTibia-flbular fractureFibula dislocationAnkle sprainContusion of ankleAnkle fractureAnkle fracture dislocationNavlcular fractureFoot Injun/Foot contusionFoot sprainFoot fractureFoot dislocation

OtherOther (diagnostic category)ContusionsAbrasions/lacerations/contusionsStatic line InjuryNerve InjuryHeat injuryTotal number of injuries

5

6.45.2

0.30.30.50.11.40.31.15.30.31.30.6

2.50.20.10.41.60.3

0.70.2

0.10.1

0.24.2

0.60.11.30.30.31.6

40.1

13.22.2

12.71.7

10.00.3

38.0

3.6

1.30.60.22.71.04.9

0.20.23.14.5

7.5

5.5

0.1

1.21.5

3.03.0

1,012

8

0.0

0.0

0.0

2.5

0.4

0.4

16.4

11.2

3.2

247.4

1.11

1.1

4.71

1.6

17.84.8

13

0.70.6

33.3

33.3

723

14

4.04

2.0

20.0

2.0

2.5

3.03

16.0

14

1

157.0

7

113

2

42

121

13

2

17.017

579

75

19.419.3

0.1

5.9

5.91.1

1.1

1.8

1.220.5

0.1

0

0.5

0.5

12.5

9.5

3

26.35.9

0.5

3.3

0.521.1

8.7

1

1.51.8

32.31.6

22.85.21.80.80.1

734

T5

Reference

75Military

17.8

8.79.1

0

9.4

9.41.1

1.1

1.1

0.7

0.1

0.2

0.1

0.3

0.3

15.5

12.4

3.1

26.94.7

0.6

1.7

1.53.51.6

9.1

1.3

0.62.3

27.32.5

19.83.61.400

1,106

16.4

7.98.5

0

8.8

8.81.1

1.1

1.9

1.7

0

0

0.2

0.3

0.3

16.0

12.9

3.1

27.84.1

0.5

2.4

0.74.71.5

10.2

0.7

1.71.3

27.21.7

19.14.81.30.30

1,169

20

14.212.9

0.41.0

0.0

11.5

1.90.44.83.8

0.6

5.0

4.0

0.80.2

0.8

0.8

15.2

3.8

3.3

8.1

50.0

1.7

6.3

3.5

9.0

22.9

1.94.6

0.0

520

21

3.63.6

0.0

3.4

1.30.81.20.24.00.1

1.3

0.20.91.50.2

1.3

0.3

0.70.35.8

5.8

81.0

0.01.2

3.1

0.41.62.64.10.3

48.5

18.90.30.50.5

3,015

12

12.012.0

0.0

14.5

12.81.7

0.0

0.0

13.7

13.7

50.4

6.0

44.4

9.49.4

109

76

7.0

0.7

0.7

4.04.0

25.07.30.1

6.035.2

388

78

2.82.3

0.6

0.0

1.7

1.7

13.61.1

1.1

0.6

10.20.6

1.7

1.7

12.51.72.3

0.6

8.0

60.2

2.8

1.10.62.31.7

0.6

5.7

11.9

25.0

2.3

5.11.15.75.7

176

79Civilian

3.3

2.3

7.6

3.3

9.3

7.3

64.5

1.68.0

301

22

4.94.9

2.4

2.42.4

2.4

4.82.4

2.4

2.4

2.4

7.3

68.2

4.9

4.9

2.4

15

2.4

279.8

2.4

4.8

2.4

2.4

41

24 Occup. Med. vol. 49, 1999

Table 5. Classic parachuting injuries

Injury Mechanism Reference

Concussion

Fracture-dislocation of shoulderTraumatic rupture of biceps brachiiPartial or complete dislocation of

acromlo-clavlcular jointStrain of the superior tibio-fibular Joint

or fracture in upper third of fibulaCompression fracture of vertebrae

Collateral knee ligament injuries

Fracture of posterior lip of tibia

Allowing head to whip back during the PLF, especially in a 3, 27backward landing

Landing without tucking elbows in tightly 10Entrapment of the static line with an arm on exiting the aircraft 23Landing on the point of the shoulder 25

Sideways strain on the leg which 'springs' the fibula head 1laterally

Backwards landing with incomplete absorption of fall through 21PLF

Excessive abduction of lower teg by somersaulting against 24rigging lines

Landing with the toes pointed down 25

transmitting the force directly through the coccyx andlumbar spine which can cause compression-type frac-tures.21 If the force is transmitted further, the head canbe jerked backwards leading to 'whiplash' injuries of theneck or indeed a closed head injury if the helmet strikesthe ground hard.5'27

If the parachutist has performed a good PLF, the land-ing forces will be transmitted across the back as he rollsover. If his elbows are not protected whilst this is hap-pening the point of the elbow may strike the groundcausing transmission of impact to the shoulder girdle.This may cause a humerus fracture, shoulder disloca-tion, acromio-clavicular joint dislocation or a fracturedclavicle.8'25 Finally the parachutist will complete the PLFand come to rest!

A number of 'classical' parachuting injuries have beenreported. These are listed in Table 5. The mechanism ofeach type of injury has been discussed above. It shouldbe noted that most of these are a reflection of a heavier-than-normal landing or poor parachuting skills.

DISCUSSION

The large number of medical papers written on militaryparachuting shows the close relationship that has devel-oped between military doctors and military parachutists.This is largely because these military doctors are oftentrained parachutists themselves and thus have absorbedsome of the culture associated with military airborneforces.

The results are skewed by the injury reports from theSecond World War period of 1941-452'3 when both theBritish and the Americans reported injury rates ten timesgreater than subsequent reports. These reports wereexcluded from the summary statistics in Table 1 becausethey reflect parachute design and procedures which havebeen substantially modified since then. The comparisonbetween reports of injury rates shows that the crudemean injury rate for military parachuting is 5.61 injuriesper thousand descents [standard deviation (SD) = 3.78;95% confidence interval (CI) = 6.77-4.90]. This com-pares to a mean for civilian parachuting of 4.37 (SD =2.08; CI = 5.0-2.84). The difference between thesemeans is 1.25 injuries per thousand descents. However,

the heterogeneity of the types of military static line para-chute programmes complicates interpretation of this dif-ference. The military parachute programme which mostclosely equates to civilian parachuting is 'day jumps fromaircraft without equipment'. The aggregated injury ratefor this type of descent is 1.78 injuries per thousanddescents (SD = 1.0; CI = 2.09-1.56) which comparesfavourably with civilian injury rates. Additional factorsthat increase the risk of injury in military parachutingrelative to civilian parachuting include: the carriage ofheavy equipment, pre-descent stress on prolonged tur-bulent aircraft flights, massed drops from multiple air-craft and night descents.

The principal source of bias between all the reports isthe variation in the definition of an 'injury'. These defini-tions vary from any casualty requiring treatment to onlycasualties receiving attention at an Accident and Emer-gency department. Clearly this variation is attributable tothe setting in which the authors work, but it does alsolimit the value of a comparison between reports.

This review has identified a number of factors thatcontribute to the injury rate for a particular military par-achute programme. Table 1 shows the reported variationin injury rates between descent by day or night and withand without equipment. The rate of injury increases aswould be expected, with balloon descents having thelowest injury rate and night jumps from aircraft withequipment the highest rate. It is not possible to makedetailed comparisons between individual parachute pro-grammes because of the wide variation in the effects ofthe various factors on single programmes.

Table 5 lists other variables that are associated withparachute injuries. Although these have been identified itis not possible to quantify the effects of many of them.The effect of windspeed is well known and is routinelyused as a limiting factor for parachuting. Although nightdescents, multiple parachutists leaving the aircraft andthe carriage of equipment are known to increase theinjury rate, these factors are fundamental to the opera-tional capabilities of parachute forces and thus cannot beavoided. Equally the choice of dropping zone isrestricted to the availability of land for military training.Many forces use specially selected areas for basic para-chute training8'10'14 which are fiat and free of hazards

M. C. M. Brtcknel and S. C. Craig: MIBtary parachuting injuries 25

but it is often necessary to use less suitable droppingzones for military manoeuvre training.

These casualty rates have been used to guide the plan-ning of emergency medical services for military para-chuting. A predicted rate based on the numbersparachuting and time of descent (day or night) can beused to determine the number of medical personnel andevacuation vehicles required to ensure suitable provisionfor any parachutist who becomes injured. A knowledgeof the anatomical distribution of injury also assists indetermining the type of emergency equipment requiredsuch as spinal boards, cervical collars and traction splin-tage. It also ensures that medical personnel are aware ofparticular patterns of injury and can examine casualtiesappropriately. These principles can be extended foroperational planning to determine the appropriate num-ber of medical personnel and equipment required tosupport a parachute operation and also the number ofparachutists required to ensure that sufficient are avail-able to undertake the operational task after landing.

A review such as this may lead a non-military reader toconsider that military parachuting is excessively danger-ous. However, no attempt has been made to compare therisk of military parachuting with other military activities.There are a number of military activities which are care-fully monitored (e.g., flying and diving). The overall riskto an individual associated with being a military para-chutist can only be assessed by a comparison of injuryrates and patterns between soldiers who are military par-achutists and soldiers who are not.

There is a clear benefit from maintaining this standardof medical surveillance of military parachuting andindeed the increasing constraints of health and safety leg-islation in many countries makes this surveillance man-datory. It is suggested that there would be greatadvantages to international authors conforming to anagreed data set to allow better comparisons. This couldsignificantly assist in creating an international 'bench-mark' standard. The definition of injury should be basedon the potential effect on military operations for whichthere would be two criteria: (1) unfit to continue themilitary mission (which would inevitably exclude someminor injuries) and (2) admission to hospital. The sec-ond category is more relevant for injury surveillancebecause these injuries are most likely to have an effect onthe soldier's long-term medical fitness.

The description of the anatomical distribution ofinjury could also be standardized, possibly using the cat-egories in Table 4. The injury to each region could bedescribed as a contusion, sprain, fracture, dislocation orfracture dislocation with additional categories for specificinjuries, e.g., closed head injury with or without loss ofconsciousness. This would also improve internationalcomparisons.

CONCLUSIONS

This paper has reviewed the reports of military para-chuting injuries in the medical literature. It is likely thatindividual armies retain other data but this is not available

in the public domain. Overall it can be seen that there is ameasurable risk associated with military parachuting.

The injury rates reported in this paper are indicationsof average expectations. It has to be anticipated thatthere will be variations in the injury rate for individualparachute programmes which will reflect chance. Fur-thermore it is important to remember the operationalrequirement that justifies the existence of airborne forceswhich is the ability to deploy a body of soldiers by para-chute at night with all their fighting equipment. Theseare the most hazardous combination of circumstanceswhich, although not practised excessively, must beincluded in training in order to ensure that the soldiersare as prepared as possible for this type of operation.

ACKNOWLEDGEMENTS

MB was supported by the Golden Jubilee Travelling Fel-lowship from the Society of Occupational Medicine andthe Drummond Foundation from the Royal Army Medi-cal Corps.

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