- 1. Review ArticleMechanical aetiology,recognition, and
treatment ofspondylolisthesisJennifer E. EarlObjectives: To provide
the reader with information about the aetiology of spondylolysis
andspondylolisthesis, and describe a new treatment approach that
has been successful in treatingthese conditions. Data sources: A
MEDLINE search was performed using the keywords`spondylolysis,
`spondylolisthesis, and `low back pain for the years 19802000. Data
synthesis:Spondylolysis is a very common cause of low back pain,
and is characterized by the presence of afatigue fracture of the
pars interarticularis region of the vertebra. The mechanical design
of thelumbar spine allows it to withstand the high forces that are
placed on it. When these stresses areabove the threshold that can
be tolerated by the bone, a fatigue fracture results. Poor
healingleads to instability of the pars interarticularis and
eventually spondylolisthesis. Although thiscondition often develops
in early adolescence, it is frequently undetected until adulthood.
Athorough assessment of adolescents with low back pain may allow
these fatigue fractures to healproperly, and prevent problems later
in life. Recent emphasis on training the deep abdominalmuscles has
shown to be a more effective rehabilitation technique than
traditional measures.Conclusions: Early detection and treatment is
the key to successful rehabilitation of spondylolysis.Decreasing
the offending activity while increasing the neuromuscular control
of the deepabdominal muscles provides the best atmosphere for bony
healing, and decreases the chance offuture complications. * 2002
Published by Elsevier Science Ltd. cIntroduction result in
spondylolisthesis, which is dened asJennifer E. Earl MEd, Low back
pain is one of the most commona subluxation or `slippage of two
adjacentATC, Doctoralmusculoskeletal complaints, and can be
vertebrae (Wiltse et al. 1975; Stinson 1993;Candidate,
AthleticTraining Research attributed to many different causes.
ChildrenWhiting & Zernicke 1998).Laboratory, and adolescents
often endure low back pain forEpidemiological studies have shown
that theDepartment ofseveral years before being evaluated by
aincidence of spondylolysis is related to
age,Kinesiology,Pennsylvania Stateclinician (King 1999). The
differential diagnosisheredity, gender, race, and activity level
(WiltseUniversity, should include, but not be limited to, tumour,
et al. 1975; Johnson 1993; Comstock et al. 1994;University
Park,Philadelphia, USA.herniated disc, spondylolysis, Hickey et al.
1997). Spondylolysis mostspondylolisthesis, infection, and
inammationfrequently manifests during adolescence
(820Correspondence to:Jennifer E. Earl, 266 (Renshaw 1995).
Spondylolysis andyears) (Johnson 1993; Comstock et al.
1994),Recreation Hall,spondylolisthesis are two conditions
thatparticularly during the teenage growth spurtPennsylvania
Statedirectly involve changes in the vertebra.(Comstock et al.
1994). Of patients less than 19University,University Park, PA
Spondylolysis is dened as a defect in the parsyears old, 32% of
those whose chief complaint16802, USA. Tel: 1 interarticularis (
pars), the region of the lamina was back pain had at least one pars
defect814 865 7936; Fax:between the superior and inferior
articular(Morita et al. 1995). The risk declines through1 814 865
1275;E-mail: jee128@psu. facets (Wiltse et al. 1975; Stinson 1993;
Whitingmiddle age, then increases slightly from 6080edu &
Zernicke 1998). Progression of the defect canyears (Johnson 1993).
There appears to be a* 2002 Published by Elsevier Science Ltd.c
Physical Therapy In Sport (2002) 3, 7987 791466-853X/02/$ - see
front matterdoi : 10.1054/ptsp.2001.0084, available online at
http://www.idealibrary.com on
2. Physical Therapy in Sport genetic predisposition in that
3350% of in deformation and incongruence of the relatives may also
have spondylolysis (Johnson vertebrae (Junghanns 1990). Although
the 1993; Stinson 1993). The genetic contribution is defect may
appear radiographically before age higher in boys than in girls,
but the overall8, symptoms may not develop until later in life
incidence is highest in girls, possibly because(Johnson 1993; Smith
& Hu 1999). girls participate in more at risk activities such
as gymnastics, gure skating, and dance (Comstock et al. 1994; Omey
et al. 2000). In the Isthmic USA spondylolysis occurs in 2% of the
African American population and 6% of the whiteIsthmic
spondylolysis is the most common type, population, while up to 60%
of native Alaskans and occurs at the L5S1 level in adolescents may
develop this condition (Wiltse et al. 1975). and young adults
(Wiltse et al. 1976; Whiting & As will become clear in the
following sections,Zernicke 1998), It results from fatigue failure
of activities that require repetitive hyperextensionthe pars due to
repetitive stress. While some or hyperexion of the lumbar spine
increases cases may indeed be dysplastic, current thought the risk
for spondylolysis/listhesis (Comstock is that very few defects are
noted before the age et al. 1994). Sports such as gymnastics,
football, of 561 (Smith & Hu 1999). Perhaps the 2 diving,
wrestling, weight-lifting, cricket, andincidence increases during
this time because rowing have exceptionally high incidenceslong
periods of sitting are introduced as (Johnson 1993; Hickey et al.
1997; Whiting & schooling begins. Spondylolisthesis results
Zernicke 1998; Leary & White 2000).when the pars elongates or
separates andSpondylolysis is classied into ve categoriesallows the
superior vertebra to slide forward on based on the suspected
aetiology: dysplastic,the inferior one (Wiltse et al. 1976).
isthmic, degenerative, traumatic and pathologic (Wiltse et al.
1976). Although these conditions have been studied for many years,
there is Degenerative much debate on possible aetiologies. The This
type of spondylolisthesis occurs more purpose of this review is to
dene each type offrequently in adults over 40, and more
spondylolysis, describe the aetiology of the two frequently in
women than men (Wiltse 1976). most common types, and present a
brief overSometimes called pseudospondylolisthesis, it view of
clinical ndings and treatments. usually occurs at the L4L5 level
(Whiting &Zernicke 1998). The slippage is a result
ofdegeneration of the disc and/or inter-segmental Classication of
spondylolysis instability, rather than a defect in the pars
Dysplastic interarticularis. Hypomobility of the L5S1 jointcauses
the L4L5 joint to become hypermobile Dysplastic spondylolysis was
rst described by and degenerative changes are likely to occur at
Wiltse (1975) and results from abnormal tissue this site as well as
anterior sliding (Wiltse et al. development of the neural arch. The
neural arch1976; Whiting & Zernicke 1998). develops from each
side of the vertebral body and joins together via sutures in the
region of the pars interarticularis (Junghanns 1990).Traumatic and
pathologic Failure or delay of suture closure during development
results in abnormal formation of These types of spondylolysis are
much less the neural arch. Examples of this would be common, and
therefore will receive little spina bida and an abnormal isthmus
angle. A attention in this review. Traumatic fracture to defective
pars is less able to withstand the the pars usually occurs in
conjunction with forces that are applied to it. In a `normal other
fractures, and heals well with vertebra, the hyaline cartilage
growth platesimmobilization. Other pathologies, such as a remain
active until about 20 years of age, sotumour, can weaken the tissue
of the vertebra intense activity during childhood that placesand
make it susceptible to damage (Wiltse et al. high stresses on the
immature spine can result 1975).80 Physical Therapy in Sport (2002)
3, 7987* 2002 Published by Elsevier Science Ltd.c 3. Mechanical
aetiology, recognition, and treatment of spondylolisthesis
Aetiology of isthmicproduced by the muscles. The pars interarti-
spondylolysis cularis is the thickest part of the lamina because it
is subjected to the high force being transferred Children and
adolescents most commonly suffer between superior and inferior
facets. The from isthmic spondylolysis, therefore the posterior
position of the ligaments is suited to aetiology of this type will
be the focus of thiswithstand the high tensile forces that are
applied review. There are two theories about whichto the posterior
elements. The viscoelastic movements cause increased stress at the
pars. properties of the ligaments indicate that their The rst and
most common is that direct loading ability to withstand forces is
dependent on the of the facets during hyperextension causes high
loading conditions (Simons 1994). A posterior stress concentrations
at the pars. The second isshift in the bodies centre of mass causes
the that unbalanced shear forces at the pars during posterior
elements to become compressed and exion causes high stress
concentrations. their structure is poorly suited for this
(SchulitzTo understand these mechanisms, it is& Niethard 1980;
Haher et al. 1993). As the spine necessary to examine the structure
and normal moves into extension, the force between the mechanics of
the lumbar vertebrae. The body offacets increases, thus directly
increasing the the vertebra is designed like a cardboard box strain
on the pars interarticularis (Schulitz & with walls made out of
cortical bone. The Niethard 1980; Simons 1994). Introducing
mechanical properties of the vertebra are highlyrotation to a spine
that is already extended dependent of the trabecular structure
within the vertebra (Whiting & Zernicke 1998).
VerticallyCOMPRESSION oriented trabeculae are supported by
horizontal ones to prevent them from buckling and further
strengthen the structure (Fig. 1). This design is well adapted to
withstand the high compressive forces on the anterior spine during
standing (Junghanns 1990; Pope 1991; Simons 1994). Age + or
repetitive stress causes a decrease in theCOMPRESSION Tension
number of horizontal trabeculae, therefore the rest of the
structure is susceptible to collapse (Haher et al. 1993). Marrow
and water in the vertebral body act as a hydraulic cushion to
absorb some of the compressive force (Haher + et al. 1993; Simons
1994; Whiting & Zernicke 1998). The discs and cartilage end
plates assist inTension this shock absorptive capacity (Junghanns
1990). Intense cyclic loading of the spine decreases the water
content of the discs and vertebral bodies, therefore decreasing the
hydraulic effect (Haher COMPRESSIONTension et al. 1993).Tension=The
posterior elements of the spine are the pedicles, laminae, and
associated processes. AllSegment of Relative of the muscles
attached to the posterior spineWeakness exert a downward force on
the posterior elements. This means the pedicle is subject to a
bending moment where the inferior surface isFig. 1 Bony trabeculae
within the vertebra are oriented compressed and the superior
surface is underaccording to the type of load that occurs at that
region. In the vertebral body, they are vertical and suited for
tension. The pedicles are thick-walled cylinderscompressive forces.
In the posterior elements, they are of cortical bone that are
suited to withstand aligned according to the line of tensile
stress. these bending forces (Simons 1994). The cortical(Reproduced
with kind permission from Pope MH et al. Structure and function of
the lumbar spine. In: layer in the lamina is very thin. The
trabeculaeOccupational Low Back Pain: Assessment, Treatment, and
are oriented in a way to resist the tensile stressPrevention. St
Louis, MO: C V Mosby).* 2002 Published by Elsevier Science Ltd.c
Physical Therapy In Sport(2002) 3, 7987 81 4. Physical Therapy in
Sport further increases the stress experienced at thevertebrae is
increased during exion. The pars (Schulitz & Niethard 1980).
This is believedanterior shear causes increased pressure on the to
be the mechanism by which gymnasts, facet joints, which in turn
increases the stress on American football linemen, divers, and the
pars (Farfan et al. 1976; Johnson 1993). wrestlers develop or
exacerbate spondylolysis. Testing has shown that when these forces
areThe second theory is that repetitive exion applied the pars is
the rst structure to movements produce unbalanced shear
forcesexperience stress concentrations (Farfan et al. that results
in stress at the pars. During quiet 1976). This mechanism has been
postulated to stance, the vertebral bodies, the spinal lead to
micro fracture of the pars that progresses ligaments, and the psoas
muscle support thewith repetitive exion. Sports such as weight of
the trunk. Compressive force isgymnastics, rowing, weight-lifting,
diving, sustained by the bony structure of the vertebral cricket
and wrestling require repetitive or bodies (Junghanns 1990; Simons
1994). Becauseconstant exion movements that exposes the of the
incline of S1, an anterior shear force acts pars to high stress
(Johnson 1993; Hickey et al. upon the L5S1 joint (Farfan et al.
1976). As the1997; Motley et al. 1998 ; Whiting & Zernicke
trunk exes, higher shear forces are developed 1998; Leary &
White 2000). Spondylolysis in (Schulitz & Niethard 1980). In
addition to rowers has been especially attributed to psoas
compression, gravity causes a exion moment at hypertrophy (Hickey
et al. 1997). The psoas L5S1. The forces acting upon a lumbar
vertebraoriginates from the anterior lumbar vertebrae in a forward
exed position are illustrated in and acts to ex the hip.
Contraction of the psoas Fig. 2. The shear stress that acts on the
pars can increases the anterior shear force on the lumbar be mostly
attributed to the forces between the vertebrae (Kreighbaum &
Barthels 1996). superior and inferior facets (Farfan et al.
1976).Fatigue fractures result when a sub-maximal The erector
spinae muscles must exert an load is repeatedly applied to a region
of bone. A extension moment to equal the bending moment fatigue
fracture at the pars interarticularis caused by the weight of the
trunk. Because mostoccurs because increased stress at that region
of the erector spinae muscles have a downwardcauses bone resorption
to occur faster than line of action, compression between thebone
formation (Martin et al. 1998). FatigueF FcMFmF Fc Fig. 2 Forces
acting upon a lumbar vertebra when the trunk is in a exed position.
F,FH forces on articular facets, causes shearing across pars
region. M exion moment caused by gravity acting upon the trunk, Fc
compressive disc force, FM force produced by posterior ligaments
and muscles.82 Physical Therapy in Sport (2002) 3, 7987* 2002
Published by Elsevier Science Ltd.c 5. Mechanical aetiology,
recognition, and treatment of spondylolisthesis fractures in this
region do not heal like they do(Fig. 3). Therefore, anything that
increased the in other locations. Less periosteal callus is
seen,compressive force also increased the facet joint and the
defect often is lled with brocartilage force (Dietrich &
Kurowski 1985). The total without bony healing (Junghanns 1990;
Johnsonreaction force was greatest for all lumbar 1993). Poor blood
supply to the neural arch andvertebrae in exion, as compared to
neutral and excessive motion at the healing site could be
theextension, and the L5S1 segment had the cause of the non-union
fractures (Junghannshighest force of all. The highest loads were
1990). If the same loads continue to be applied, found in the pars
when the trunk was exed to the defect can become unstable and 808.
Tests to failure resulted in fracture of the spondylolisthesis
occurs (Farfan et al. 1976). pars in all vertebrae that were
tested. AnFatigue tests have been performed on cadaverinteresting
nding was that, when intra- vertebrae to determine where and when
aabdominal pressure was increased, the reaction fatigue fracture
might occur (Cyron & Hutton force at all levels was decreased
by as much as 1978). A model was designed to simulate an 20% (Fig.
4). This supports the theory that average person walking with a
50-kg back-packcontraction of the abdominal muscles lessens with
408 of trunk exion. Out of 74 vertebraethe compressive load on the
vertebra by acting tested, 53 fractured across the pars, theas a
hydraulic lift (Dietrich & Kurowski 1985; remainder fractured
in the pedicles or did not Junghanns 1990; Simons 1994). fracture.
This indicates that the posterior In addition to intra-abdominal
pressure, elements are the most susceptible to fatigue passive
structures have been hypothesized as fracture under sub-maximal
cyclic loading. Inplaying a role in reducing anterior shear. the
1430 year age group, all vertebraeAccording to one group of
researchers, once 608 fractured within ten hours of cyclic
loading.of exion is reached, the posterior ligaments and The 4060
year group had a very wide range offascia become taut and resist
the bending failure times, from 2 minutes to 100 hours whenmoment.
Beyond 608, the posterior ligament the cyclic loading was stopped.
This indicated system becomes tighter, producing more that the
neural arch was stronger during thisposterior resistance, thereby
decreasing the stage of life than during the adolescent period.
anterior shear forces imposed on the facets The oldest age group
(6080) fractured within 8(Farfan et al. 1976). If the posterior
connective hours, suggesting that osteoporosis or other disease had
weakened the bone (Cyron & Hutton 1978). The results of this
study are supported by Schulitz & Niethard (1980), who also
demonstrated that during axial loading of the spine even small
movements greatly increase the strain at the pars.One group of
researchers examined the loadsFa and stresses placed on the lumbar
spine during different conditions with the use of a model. An epoxy
resin vertebral model was created from information gained through
radiographs of a human spine and cadaver dissection. TheFc-N model
was created with relatively accurate Fc-H geometric and physical
properties. Forces exerted by the erector spinae and abdominalFc
muscles were altered, as well as the amount of trunk exion.
Reaction forces of interest were Fig. 3 The position of the
intervertebral disc relative tothe inferior facet causes the
horizontal component of the compressive force between vertebral
bodies,the intervertebral disc compressive force to be additive and
the facet joint force. Due to the relationship with the reaction
force of the inferior facet. This of the inferior facet to the
intervertebral disc, it increases the anterior shear at the pars
interarticularis.Fa articular shear force, Fc Compressive force,
was assumed that the shear component of theFc-H horizontal
component of compressive force, intervertebral force added to the
facet joint forceFc-N normal component of compressive force.* 2002
Published by Elsevier Science Ltd.c Physical Therapy In Sport(2002)
3, 7987 83 6. Physical Therapy in SportFdnkN Pabd = 05 Pabd = Popt
4 3 2 1 -80o -60o -40o -20o0o 20o 40o 60o 80o 100o 120o 140o 180o
Fig. 4 The relieving effect of the intra-abdominal pressure (load
in hands 400 N) to the normal force (force that compresses the
vertebrae) in the motion segment L5S1. Positions of the body out of
the range 20 to 100 were not recorded in vivo. (Reproduced with
kind permission from Dietrich M, Kurowski P. The importance of
mechanical factors in the aetiology of spondylolysis. Spine 1985;
10(6) 532542). tissues are lengthened, more anterior shear can
prior to the age of six, but then increases to 5% occur during
exion before the passive restraints at that age. This incidence is
equal to that in the are activated. This increases the demand on
the general population (Smith & Hu 1999). The muscles to
balance the force (Farfan et al. 1976).increase may be attributed
to two causes: The combination of increased shear andFirstly, it is
around this age that formal increased posterior muscle force puts
additionalschooling begins. Children are likely to be stress on the
pars. When these muscles become sitting for longer periods of time
than they have fatigued there is even less restraint to thebefore.
While this is not likely to cause enough damaging anterior shear
forces (Farfan et al. pain or disability to send the child to the
1976; Johnson 1993; Motley et al. 1998).doctor, it may be starting
the spondylolithicThe exion mechanism seems to explain whyreaction
that will become a problem later in life. factors such as prolonged
sitting, bending, and The second cause is the introduction of
activities that demand repetitive exionorganized sport and
practices. Society is exacerbate symptoms of spondylolysisdemanding
much more out of young athletes (Junghanns 1990). Two common
mechanisms when their skeletons are not physically mature. by which
workers compensation injuries occur What may have previously been a
benign is prolonged sitting and incorrect liftingdeformity of the
pars develops into a painful techniques. Sitting with poor posture
places thecondition that limits activity and can lead to lumbar
spine in a functionally exed position,long-term problems. and the
anterior shear force will be constant. If the muscles do not
balance this, the facets and Clinical examination pars are
subjected to continued high stress. While lifting, anterior shear
is affected by howPatients with spondylyolsis/-listhesis present
much weight is being carried, the distance of complaining of pain
that began as incidental the weight from the body, and the amount
of and worsened with activity. Young athletes trunk exion (Johnson
1993).often endure the pain for a long time before theyAnother
interesting observation is that theare seen by a physician (Stinson
1993). The pain incidence of spondylolysis is virtually zerois
exacerbated by extension, rotation, and84 Physical Therapy in Sport
(2002) 3, 7987* 2002 Published by Elsevier Science Ltd.c 7.
Mechanical aetiology, recognition, and treatment of
spondylolisthesis extending from a exed position (Stinson 1993;of
the injury can be determined by radiographic Comstock et al. 1994;
Motley et al. 1998). Weak ndings. An old injury is detectable on
abdominal muscles increase lordosis, whichradiographs, but no
active healing is evident increases the anterior shear on the
vertebrae with a bone scan. In this case, the defect has (Motley et
al. 1998). Hamstring tightness is aprobably lled with brocartilage
and scar frequent occurrence, and is thought to be antissue, and
bony healing is no longer possible attempt to tilt the pelvis
anteriorly to move the (Johnson 1993; Renshaw 1995). If the patient
is center of mass forward on the vertebral bodiessymptomatic, pain
control modalities such as (Stinson 1993; Comstock et al. 1994;
Motley et al.NSAIDs, thermal agents, and electrotherapy 1998). If
spondylolisthesis has occurred, should be used until symptoms
resolve. palpation of the lumbar spine will reveal a Conservative
rehabilitation can include `step-off of one spinous process to the
next. Theabdominal strengthening, postural and step-off is a result
of the vertebrae superior to the movement mechanics training,
hamstring and damaged one slipping forward (Motley et al. psoas
stretching, pelvic stabilization training 1998). A `pelvic waddle
gait is described as a (Comstock et al. 1994). A soft lumbosacral
brace shortened stride length, with increased pelvicis often used
in conjunction with rehabilitation rotation and decreased knee
extension. This is(Morita et al. 1995; Smith & Hu 1999).
High-risk believed to be a result of the hamstring
tightnessactivities should be limited, and follow-up (Comstock et
al. 1994). evaluation is necessary to monitor
progressionSpondylolisthesis will appear on lateral and (Johnson
1993; Comstock et al. 1994). oblique radiographs. The severity is
most oftenIf plain radiographs do not show a fracture measured by
the Talliard method that dividesline, and a bone scan reveals
increased uptake, the slip distance by the total sacral thickness
and bony healing is possible with proper this is interpreted as
percent slip. Spondylolysisimmobilization (Comstock et al. 1994;
Renshaw in its early stages may not be visible on plain 1995). Bony
healing is possible if symptoms radiographs. A bone scan will
reveal increasedhave been present for less than two months uptake
in the pars indicating a stress reaction (Renshaw 1995). Morita et
al. (1995) determined (Letts et al. 1986; Stinson 1993; Comstock et
al. that conservative treatment was successful and 1994; Renshaw
1995; Omey 2000). bony healing occurred in 73% of those
withRadiography can be used to determine early stage spondylolysis
(hairline fracture), whether a pars defect occurring in a young
childwhile this number declines to 0% for those with will progress
to spondylolisthesis. The extent of terminal stage
spondylolisthesis (separation the listhesis has been correlated to
the amount ofwith sclerotic changes). This supports the damage to
the cartilage end plate of thenecessity of early detection to
obtain optimal vertebrae (Ikata et al. 1996). Radiographsresults.
Lumbar movement is limited by a rigid demonstrating a listhesis
also revealed brace similar to that used in scoliosis treatment.
signicant damage to the end plate of S1 or L5. The brace should be
worn 23 hours a day for Increased damage to the endplate
increases12 weeks, with follow up X-rays every 4 weeks instability,
and therefore increases the likelihood (Letts et al. 1986; Comstock
et al. 1994; Renshaw of listhesis. It was once thought that the
shape of 1995). If, at the end of 12 weeks, symptoms L5 and S1 were
factors in how much a segmenthave resolved, bracing is continued
for another slipped, but it is now believed that the shape of 6
months (Comstock et al. 1994). If symptoms L5S1 is a result of
endplate damage. The have not resolved with bracing and decreased
amount of endplate damage present can be used activity, surgical
intervention should be as a predictive factor of how much the slip
willconsidered. This treatment is most successful in progress
(Ikata et al. 1996). young children whose growth plates are still
open. Displacements that progress to 50% or more are treated
surgically. Bilateral fusion of Treatment the transverse processes
of the involved Treatment is based on the age of the patient, the
segments is a common procedure (Comstock age of the fracture, the
progression of the et al. 1994; Renshaw 1995). Any case of
listhesis, and the patients activity level. The ageadolescent
spondylolysis should be treated* 2002 Published by Elsevier Science
Ltd.cPhysical Therapy In Sport (2002) 3, 7987 85 8. Physical
Therapy in Sport conservatively to prevent progression and1975). It
is now known that defects in the pars problems in later
life.interarticularis are not present at birth in theSome
researchers are suggesting thatmajority of the cases, and instead
are often the traditional treatment of rest and lumbar exionresult
of fatigue fractures. The high incidence of exercises may not be
appropriate for spondylolysis may be due to increased spondylolysis
(Panjanbi 1992; Renshaw 1995;compression of the posterior elements
due to Richardson & Jull 1995) Patients with lumbar extension,
or increased shear caused by exion dysfunction often lack voluntary
control of theon the immature spine. The incidence of deep
stabilization muscles and therefore use spondylolysis in young
people may be on an substitution patterns to stabilize the spine
increase as a result of more children being (Panjabi 1992;
Richardson & Jull 1995). Exercisesinvolved in highly
competitive training at an such as the pelvic tilt and abdominal
crunch early age. require strong contractions of the large torque
Testing has indicated that the pars producing muscles which may
enforceinterarticularis is subjected to very high forces
substitution patterns. The abdominal hollowing and indeed is the
mechanically weak link of the technique has been described by
Richardson vertebra. There are several mechanisms and Jull (1995)
as targeting the transverseavailable to decrease the forces imposed
on the abdominus and internal oblique. To perform facet joints,
such as increasing intra-abdominal this activity, subjects are
instructed to lift their pressure, strengthening the erector
spinae, and ribcage, and attempt to draw the navel closer to
tightening the posterior ligamentous structures. the spine.
Biofeedback would be an effective toolHowever, when repetitive
movements that stress to assist patients in performing this task
without the pars are performed, normal protective substitution
patterns (Allison et al. 1998). mechanisms sometimes fail,
subjecting the bone Contraction of these muscles increases intra-to
fatigue failure. Repeated stress after pars abdominal pressure
which has been shown to failure can cause adjoining vertebrae to
slide decrease the stress on the pars interarticularis apart,
resulting in spondylolisthesis. If the initial (Dietrich &
Kurowski 1985; Junghanns 1990; defect is detected early, bony
healing can occur, Simons 1994).with conservative treatment
preventing furtherRecent research indicates that targeting
theseparation. Most often, the defect is lled with deep stabilizing
muscles of the abdomen andbrocartilage and therefore will always be
lower back may be more benecial thanweaker than the rest of the
bone. Much debate traditional rehabilitation exercises in thestill
exists on which type of motion is more likely treatment of
spondylolysis (OSullivan to cause the problem, but it seems that et
al. 1997). A group of patients with unbalanced shear forces are a
likely culprit. spondylolysis who performed specic exercises Given
the substantial effect of the deep to train the deep abdominal
muscles reported abdominal muscles on spinal mechanics, it is
decreased pain, increased function, and less important to include
specic exercises to train medication use as compared to a group of
these muscles. Traditional exercise routines may similar patients
who performed traditional enforce substitution patterns and, while
the exercises (OSullivan et al. 1997). Once patient recovers
temporarily, future recurrences contraction of the deep abdominal
muscles wasare likely due to continued improper mastered,
functional positions and activitiesmechanics. Early detection of
spondylolysis in were performed while maintaining the children is
crucial to insure bony healing and contraction of the deep
abdominals. This minimize the chance of future instability. Any
allowed patients to learn how to safely performchild or adolescent
being evaluated for low activities that had been painful.back pain
should be carefully screened forspondylytic defects.
ConclusionReferences Spondylolysis was once considered to be
aAllison G T, Godfrey P, Robinson G 1998 EMG amplitude congenital
condition that was present at birth assessment during abdominal
bracing and hollowing. and progressed through adulthood (Wiltse et
al.Journal of Electromyography and Kinesiology 8: 515786 Physical
Therapy in Sport (2002) 3, 7987 * 2002 Published by Elsevier
Science Ltd. c 9. Mechanical aetiology, recognition, and treatment
of spondylolisthesis Comstock C P, Carraggee E J, OSullivan G S
1994Motley G, Nyland K, Jacobs J, Caborn D 1998 The
parsSpondylolisthesis in the young athlete. Physician
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Medicine 22 (12): 3946 spondylolisthesis progression. Journal of
Athletic Cyron B M, Hutton W C 1978 The fatigue strength of
theTraining 33 (4): 351358lumbar neural arch in spondylolysis.
Journal of Bone Omey M L, Micheli L T, Gerbino P G 2000
Idiopathicand Joint Surgery 60B (2): 234238 scoliosis and
spondylolysis in the female athlete. Clinical Dietrich M, Kurowski
P 1985 The importance of mechanicalOrthopaedics and Related
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