Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has many disorders that may affect both movement and posture (Bobath 1991). Spastic cerebral palsy influence 70% of child population with CP and happen when white matter tracks damage between the cortex and the spinal cord. Moreover, a main problem for children with spastic CP is their feet and leg muscles, which might shorten or tighten around certain joints (Bjorklund 2006). C

1. Comparison between Hamstring Lengthening Tendon and Hamstring Tendon
Transfer on Child’s Crouch Knee Cerebral Palsy with Gait Outcome
Introduction:
Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has
many disorders that may affect both movement and posture (Bobath 1991). Spastic
cerebral palsy influence 70% of child population with CP and happen when white
matter tracks damage between the cortex and the spinal cord. Moreover, a main
problem for children with spastic CP is their feet and leg muscles, which might
shorten or tighten around certain joints (Bjorklund 2006). Crouch knee is one of
many gait pattern for spastic cerebral palsy and described as walking with sever
knee flexion during stance phase associated with other problems such hip and knee
flexion (Flynn and Wiesel 2012). Therefore, orthopaedic surgery is necessary for
children who is in a worse condition in order to enhance their mobility (Bjorklund
2006). The main objective of surgery is to improve or regain function by treating
deformities of bone or muscle shortening, such as the hamstring (Kocher and Millis
2011). Hamstring tendon lengthening and hamstring tendon transfer are two main
surgeries that could improve crouch knee especially in mid-stance that require full
knee extension (Dreher et al. 2013). However, Lengthening tendon of hamstring by
surgery technique is considered as the standard intervention to enhance crouch
knee (Chang et al. 2004). Thus, there are some argument about which has more
positive impact on crouch knee between two types of surgeries (Dreher et al. 2013).
I found 4 articles that make comparison between both surgeries in kinematic with
little attention of kinetic parameters this gap lead me to do scrutiny investigation to
answer the following question: Which has a significant improvement between
hamstring tendon lengthening or hamstring tendon transfer surgery in the
biomechanics aspect of gait after correction crouch knees of children with cerebral
palsy and how that reflect on physiotherapy clinic?

2. Normal Gait Analysis:
Gait analysis provide large picture that helps to understand normal
and abnormal pattern of gait and aims to assist movement diagnosis which
intervention is more suitable for certain condition. The gait cycle illustrates
gait in tow parameters that are distance (spatial) and time (temporal). The
gait cycle starts with heal contact on ground and ends when the same heal
contact the surface again. There are two phases of gait cycle that are stance
(heel strike, foot flat, midstance, heel-off, and toe off) and swing phase
(acceleration, midswing, and deceleration). First, stance phase is defined as
the time consuming when the foot on the ground and represent 60% of gait
cycle. Second, swing phase is defined as the time consuming when the foot
does not contact with floor and represent 40% of gait cycle. In addition, there
are two periods of double support that means two legs contact with the
ground at the same time in order to shift body weight form one leg to another
during two different phases. Moreover, the other parameters that can help
understanding better gait analysis are steps and stride. There are two steps
right and left lead to a stride that equal the gait cycle. The distance between
heel contact of one foot to the opposite foot heel point define as step length
while stride length is a point form heel contact of one extremity to heel
contact again for the same limb.

3. The types of Gait Analyses:
The gait analysis is divided into two parts: Kinematic, which illustrates
movement angle without force consideration and Kinetic, which illustrates
movement with force involved. Considering kinematic of knee that is related
to topic question in two different phases. First, knee stance phase in heal
contact to foot flat the knee angel bend from 0-15 degree in flexion position
and quadriceps contracts first to hold knee in extension and then eccentrically
to reduce flexion and control movement. Second, foot flat to mid-stance the
knee extend from 15-5 degree the movement starts from flexion toward
extension and quadriceps just work at the beginning of movement. Third, mid-
stance to heel off the knee continues to extend from 5 degree of flexion to 0
degree (neutral) and no muscle activity required. Finally in stance phase,
from heel off to toe off the knee starts flex from 0 to 40 degree of flexion and
quadriceps needed to control knee flexion. However, in the knee swing phase
there are three stages. First, from acceleration to mid-swing the knee become
flex form 40 to 60 degree and the muscle activities are biceps femoris (short
head), gracilis and sartorious contract concentrically. Second, mid-swing
phase the knee moves from flexion 60 to 30 degree of extension. Finally,
deceleration phase the knee continuous to extend until 0 degree and
quadriceps contracts concentrically to stabilize knee in extension position
(O’Sullivan and Schmitz 2007). The second type of gait analysis is kinetic that
focus on movement with force and torque consideration. First, force is a
fundamental element of kinetic that helps to distinguish between normal and
abnormal gait pattern. The force that applied under the ground of leg when
the subject walks called foot force. In contrast, the force that applied to the
leg by the surface defined as reaction force. To describe the ground reaction
force, there are three orthogonal axes: vertical, anterior-posterior and medial-
lateral force. Second important element in kinetic is joint torque that focus on
ground reaction force applied under leg during walking generate external
torque (Neumann 2013).

4. Abnormal kinetic pattern of crouch knee:
Crouch knee define as more knee flexion in the stance period, with variation of
range of motion during swing period (Sutherland and Davids 1993). Child with
spastic cerebral palsy will suffering from anterior knee pain because the great
amount of loading on the patellofemoral joint that may affect gait and function
(Ganjwala 2011). First, the hip joint angel in crouch gait persistently increased in hip
flexion through gait cycle and the hip joint was large extensor moment in initial
contact and mid-stance by -0.8 Nm/kg because contracture of flexor knee muscle.
Second, the Knee in initial stance increased flexion by 50-degree more than normal
gait (0-15 degree) and continually increased flexion through the stance period (Lin
et al. 2000). Thus, more knee flexion will create a high extensor moments in knee
(Matjačić et al. 2006). However, the knee extension moment will be decrease when
ankle planter-flexion moment increase in mid stance because of soleus firing to
accelerate knee extension (Neptune et al. 2001). The vertical ground reaction force
passes behind knee joint and creates internal extension moment. Furthermore, the
ankle is an excessive dorsiflexion and ground reaction force moves forward and
generates external Doris-flexor and internal planter-flexor moment. In EMG,
hamstring muscles activate in initial stance and terminal swing. To sum up, stance
period is the main issue of crouch group especially in mid-stance when body unable
to shift weight because of excessive knee flexion. Another issue is excessive ankle
dorsiflexion that lead to generate internal planter flexor because the ground reaction
force moves anteriorly (Lin et al. 2000).
Biomecanics different beteen hamstring tendon lengthening and transfer:
To treat the pervious crouch knee complication, there are two main operation
that may improve crouch gait if the hamstring contrctuer is the reason. First, distal
hamstring lengthening surgery that procedure is tendomized or elongated tendon by
intramuscular tendon release (Feng et al. 2012). The adentages of distal hamstring
lengthening is improve rang of motion of hip and knee esspically in knee extension
in mid-stanse as well as sort of kinetic such knee and hip power (Rethlefsen and
Tolo 1999). However, the disadanteges of distal hamstring lengthening are

5. hyperlordosis, increase anerior pelvic tilit and recurent knee flexion (Baumann et al.
1980). The second operation technique that may enhanse crouch knee disfunction
is a hamstring tendon transfer that is transfer both semitendinouses and gracilis
tendons to the adductor tuberecle in distal part of femer (Flynn and Wiesel 2012).
Therefore, this process of tendon transfer will change middle hamstring from
biarticular into monoarticular mucele (Fitoussi and Bachy 2015). The advantages of
hamstring transfer are more than hamstring lenthening tendon in kinematic as well
as kinetic at peak hip power (Feng et al. 2012). However, the disadvantages are
loss knee flexion in swing phase and increase pelvic tilt (Dreher et al. 2013).
The Chang et al.(Chang et al. 2004) ,who includeS 83 limbs, and Feng et al
(Feng et al. 2012), who includeS 20 limbs, tend to investigate distal hamstring
lengthening that correct crouch knee disfunction. They found in primary hasmstring
lengthening the popliteal angel decreased approximate 15 degree, the knee flexion
at foot contact was decresed about 10 degree and pelvic tilit was incresed about 2
degree from pre to post-operative. In comarison, the Feng et al (Feng et al. 2012),
who includes 18 limbs, and De Mattos et al (De Mattos et al. 2014), who includes 32
limbs, investigate the post one year hamstring tendon transfer surgery outcome.
The result was an imrovment in poplitial angel that decreased approximatlly 10
degree, the knee flexion at foot contact was decresed 15 degree and pelvic tilit was
incresed approximatlly 6 degree after suergery. Both surgeries have the similar
outcome on kinematic elements with slightly difference in anterior pevic tilt in
hamstring tendon transfer group.
On the other hand, when compear between two surgeries on kinetic elements
we obvious notice that while peak hip and knee power decresed approximately 0.5
w/kg in hamstring lengthening group, the peak hip power was increasd significantly
0.4 w/kg in hamstring transfer group. Thus, there is some improvement in short time
may be happen after hamstering tendon lenghrening that might increase knee
extension at mid-stance phase, but increse pelvic tilt and loss hip and knee power
support the idea that elongate muscle tendon may lead to loss mucsel
contractability as a result the muscle become weak (Fitoussi and Bachy 2015).
However, there are two miss assumtion that is the anterior pelivic tilt does not has
clinical significant even there is a statistical difference in both types of surgery (Feng

6. et al. 2012). The second miss assumtion is about the peak hip power is not
deterioration in hamstring tendon lengthening group over time (De Mattos et al.
2014). However, both studies that have miss assumtion show small sample size
that may affect on result and contradicted the study that include large power size
(Rosenthal et al. 2011). Furthermore, the drwabacks of hamstring tendon
lengthening surgery, which are anterior pelvic tilt and hamstring weakness, may
increase chance of recrouch knee happen in long time period because of vertical
ground reaction force that cause more knee extention moment during loading
response and mid-stance (Matjačić et al. 2006). This conceren was agreed by
Chang et al (Chang et al. 2004) who notice the recurrence crouch knee in 18
children who underwent hamstring lengthening tendon.
investigating the long-term follow up of hamstring tendon lengthening and
transfer will help to know the effect of surgery is remaing conistant or has
deterioration effect. Thus, I found (De Mattos et al. 2014) ,who studied the the
comparison of hamsting transfer with hamstring elongation in long-term follow up,
provide me the imapct of hamstring elongation and transfer on long term. The study
include 18 limbs that showed similar imrovement in the perivious studies in poplitial
angel, minimum knee flexion in stance phase , average of pelvic tilt and worse in
peak hip power in stance phase pre and post-operative. However, when compear
between post-operative and long-term we will see obviously improvement in poplitial
angel about 6 degree in long-term, minimum knee flexion incresed slightly from 0.5
degree, average pelvic tilt decrese from 1 degree and peak hip improved
approximate 0.2 w/kg in long term follow-up. Therefore, Decreasing pelvic tilit
degree and imroving peak hip power in long term might contradicte privious
assumation about recurence of crouch knee after hamstring lengthening surgery,
but this findinding need more investigation to confirm the long-term effect of
hamstring tendon lengthening because of number of sample size. In contrast,
hamstring tendon transfer long term group was slightly increse in poplitial angel 4
degree, the average pelvic tilt was slightly deterioration 1 degree and minimum
knee flexion in stance was almost double incresed by 5 degree in long term follow
up. Although, all parameters indicate the long term hamstring tendon transfer
become deterioration slightly and indicate the potiential recurence of crouch knee,
the hip power superisingly improved approximate 0.2 w/kg in long-term follow up.

7. Thus, this improvement in peak hip power raise my conceren and encourge my to
invstigate why hip power improved while all parameters decresed. The answer that
may solve this concern is hamstring tendon transfer may has ability to stablize the
pelvis and generate hip extenstion power that will move pelvic posteriorly because
the hamstring moment arm become greater when this muscle become
monoarticular rather than biarticular (Dreher et al. 2013). Moreover, another
explenation is spastic childern cerebral palsy suffering form different muscle not just
spesific singel muscle, so aouther muscle rather than hamstring that has enough
power may attribuate to crouch knee (Flynn and Wiesel 2012).
Relatetd to the article that include in this assingment, comparing between
hamsrtring tendon lengthening and transfer raise my criousity to understand what
has more positive impact on child’s gait. Therefore, the hamstring tendon transfer
show a postive impact on pelvic tilt degree and poplitial angel that was more
improve. Morovere, the result of hamstring tendon transfer, which would change
hamstring muscle from biarticular muscle into monoarticular muscle, is create large
moment arm that generate high amount of hip power as a consequence and
reflects on kinematic of knee postively to correct crouch gait. However, lenthening
hamstring tendon will lose hip and knee power even one study show long-term
imrovement because of the relative small power size in that study comparing with
other studies that show large power size and recuerrence crouch knee. In general,
the hamstring tendond transfer show a postive impact on child’s knee kinematicly
and kineticaly that may enhance the quality of the gait.
Clinical Implication:
The hamstring tendon lengthening has some drawbacks that may influence
Child’s gait negatively such as anterior pelvic tilit, decrese hip and knee power and
may lead to recurence crouch knee (Dreher et al. 2013). The reason for that is
elongation contructer muscle that will loss its contractibility that lead to weakness
(Jozsa et al. 1990) and muscle implance in pelivic also may contribute to increse
pelvic tilit (De Mattos et al. 2014). foucsing on hamstring and qudercips flexability
and strenthing in knee will stablize knee joint and prevent recurrent crouch knee

8. (Tecklin 2008). One of the best exercise that may improve muscle strengthining and
coordination for both hamstring and qudercips is cycling therapy (Rimmer 2001).
Fowler et al (Fowler et al. 2010) did randomized control trail study on 68 child with
spastic cerebral palsy and the result was significant improvements in, gross motor
function, and some measures of strength such hamstring in the cycling group.
Therefore, the cycling therapy will be recommended to include in rehabilitation
protocol after hamstring tendon lengthening operation to maximize knee and hip
power. Another concern about hamstring tendon lengthening is increase pelvic tilt
because of weakness of hip extensor that show in hip power and hip flexor
contracture that may lead to recurrent flexed knee (Dreher et al. 2012). Thus,
stretching exercise for hip flexor and strength hip extensor should be considered to
minimize the side effect of hamstring tendon lengthening surgery (Sahrmann 2013).
On the other hand, hamstring tendon transfer has more advantages than hamstring
tendon lengthening in pelvic tilt and great hip power that reflect on hamstring
strength, but the main issue in hamstring tendon transfer is decrease knee flexion
during swing phase because of the hamstring tendon was changed into distal femur
side (Dreher et al. 2013). To increase knee flexion in swing phase strength
gastrocnemius, which is act as knee flexion and ankle planter flexion, should be
include in treatment plane after hamstring tendon transfer surgery (Rha et al. 2015).
The reason of anterior pelvic tilt in transfer group is different in lengthening group
that because the unequal force between hip flexor and extensor muscle that
illustrate in peak hip power (Dreher et al. 2013). Therefore, strengthening exercise
in hip flexor might equalization pelvic power and reduce anterior pelvic tilt
(Mansfield and Neumann 2014). In general, the hamstring tendon transfer surgery
shows significant difference in hip power and I did not find article conclude
recurrence of flex knee, while the hamstring tendon surgery shows the opposite
effect. The plane of treatment is different between two types of surgery in tendon
transfer group the gastrocnemius should be strength, while hamstring should be
strength in lengthening group. Both groups should strength and stretches selective
muscle group hip flexor or extensor depend on cause of the anterior pelvic tilt and
cycling will be best training for both groups.

9. Conclusion:
The cerebral palsy child, who has crouch knee, faces difficulties in walking
such as hip and knee flexion because of hamstring contracture(De Mattos et al.
2014). The surgery aims to enhance increase knee extension in mid-stance rather
than knee flexion ((Feng et al. 2012). The types of surgery that could help improving
crouch knee is hamstring tendon lengthening and hamstring tendon transfer. Both
surgeries show significant difference in kinematic parameter that provides scientific
evidence to enhance children’s gait. However, hamstring tendon transfer shows a
great positive impact on both kinematic and kinetic parameters that would be more
beneficial than hamstring tendon lengthening. In addition, the treatment plane is
different in both groups because of variation that cause the problem, but the cycling
therapy should be included as a treatment for both groups to improve muscle power
for different muscle. To sum up, these findings may assist both physiotherapist and
pediatric surgeon to decide which treatment and surgery most appropriate for
crouch knee gait in CP child.

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