Abstract Closed-chain exercise protocols are used extensively in rehabilitation of knee injuries and are increasingly used in rehabilitation of shoulder injuries.. This helped to define
Trang 1Orthopaedic surgeons are intimately
involved in the rehabilitation
pro-cess, in that they establish the
ana-tomic diagnosis of the injury,
deter-mine the timing of entrance into and
exit from the rehabilitation program,
and select the modalities and
exer-cises that are used Even though they
usually do not physically
demon-strate or personally supervise the
exercises, they must understand the
basic concepts underlying the
vari-ous types of exercises and the timing
of exercise progressions, in order to
effectively communicate with the
physical therapists and coordinate
the best program for the individual
patient’s needs
Most current rehabilitation
pro-grams emphasize functional
resto-ration of the injured part, which
requires not only repair and healing
of injured tissues but also restoration
of correct positioning and
move-ment of joints as well as activation of
muscles in the proper sequence so as
to achieve normal function
Closed-chain protocols have been advocated
in rehabilitation because they have characteristics that encourage more complete functional restoration These exercises have been used extensively for anterior cruciate ligament (ACL) injuries as a major component of
“accelerated” knee rehabilitation, as well as for rehabilitation of patients with patellofemoral and shoulder injuries
Despite increasing usage, there is still controversy about what closed-chain exercises are and how and when to use them Neither is there
a common understanding of what defines a closed-chain exercise, how closed-chain exercises promote functional restoration, and what the best closed-chain exercises are for different stages of the rehabilitation process To be able to appropriately prescribe and utilize these tech-niques, the physician must first un-derstand the underlying physiology and biomechanics of closed-chain rehabilitation
Definitions
The human body produces motions and performs complex skills through sequential activation of muscles and movement of body segments, or links.1,2 This link activation, which may be activity- or sport-specific, is termed a “kinetic chain.” There are two broad-based classes of kinetic chains—”open,” in which the termi-nal link of the chain is not loaded and is freely movable (mobile end,
no load [MNL]), and “closed,” in which the terminal link is con-strained or immovable due to a fixed position or large load (fixed end, external load [FEL]) The mo-tion of the foot of a kicking leg is an example of an MNL kinetic chain
A pure FEL kinetic chain is exempli-fied by a fixed foot during a squat exercise Force generation, force distribution, joint motion, muscle ac-tivation, and resultant tissue stress can be quite different in the two classes
Dr Kibler is Medical Director, Lexington Sports Medicine Center, Lexington, Ky Mr Livingston is Clinical Specialist, Lexington Sports Medicine Center.
Reprint requests: Dr Kibler, Lexington Sports Medicine Center, 1221 South Broadway, Lexington, KY 40504.
Copyright 2001 by the American Academy of Orthopaedic Surgeons.
Abstract
Closed-chain exercise protocols are used extensively in rehabilitation of knee
injuries and are increasingly used in rehabilitation of shoulder injuries They
are felt to be preferable to other exercise programs in that they simulate normal
physiologic and biomechanical functions, create little shear stress across
injured or healing joints, and reproduce proprioceptive stimuli Because of
these advantages, they may be used early in rehabilitation and have been
inte-gral parts of “accelerated” rehabilitation programs The authors review the
important components of a closed-chain rehabilitation program and provide
examples of specific exercises that are used for rehabilitation of knee and
shoul-der injuries.
J Am Acad Orthop Surg 2001;9:412-421
Upper and Lower Extremities
W Ben Kibler, MD, and Beven Livingston, MS, PT
Trang 2Steindler2 was the first to
de-scribe the differences in muscle
activation and joint motion that
occur when the distal end of the
arm or leg in a kinetic chain meets
considerable resistance compared
with when it is freely movable His
definition of a closed-chain
condi-tion required that the foot or hand
meet enough resistance to prohibit
or restrain its free motion, and that
the resultant extremity muscle
acti-vation was sequential from distal
to proximal in the extremity
Physical therapy protocols have
been developed to take advantage
of the force-generation and loading
characteristics of closed-chain
exer-cises There has been wide variety
in their application, but in general,
closed-chain protocols include a
progression of exercises that are
based on application of a load to the
distal end of an extremity that does
not move freely due to either
posi-tioning (e.g., on a wall or on the
ground [Fig 1]) or the load
charac-teristics (e.g., axially applied heavy
load) Subsequent joint motion takes
place in multiple planes while the
limb is supporting weight These
conditions differentiate these
exer-cises from “open chain” exerexer-cises,
such as knee extensions, trunk
ex-tensions against gravity, and isolated
rotator cuff exercises with tubing or
weights
Dillman et al3described
condi-tions that define closed-chain
exer-cises They realized that the effect
of the exercise on joint positions
and muscle activations is the critical
point in defining a closed-chain
exercise They felt that closed-chain
exercises have to include relatively
small joint movements, low joint
accelerations, large resistance
forces, joint compression, decreased
joint shear, stimulation of joint
pro-prioception, and enhanced dynamic
stabilization through muscle
coac-tivation They also recognized that
the amount of load at the terminal
end of the extremity is as important
as the motion of the extremity
Even if the distal end of the extrem-ity is somewhat mobile, a large enough load can still create physio-logic conditions that replicate closed-chain characteristics This enlarged the concept of a closed-chain exercise from being only an FEL activity to include mobile end–external load (MEL) activities
as well, making it more applicable
to the upper extremity For exam-ple, a military press (an MEL exer-cise) can have closed-chain effects similar to those of a pushup (an FEL exercise) This concept has been validated by Blackard et al,4
who found that there was no differ-ence in muscle activation between equivalently loaded upper-extremity exercises with either fixed or mobile ends They concluded that external loading characteristics were more important than arm motion in de-scribing and simulating human activity
Lephart and Henry5modified the MEL condition to include two differ-ent external load conditions—axial load (e.g., military press) and rotary load (e.g., arm rotations with dumb-bells) This helped to define types of exercises but did not change the con-cept that closed-chain joint loading and muscle activation characteristics can be obtained with a movable dis-tal end However, it enlarged the scope of the types of exercises that can be employed in a closed-chain rehabilitation program
Livingston6 developed an opera-tional definition to guide implemen-tation of closed-chain exercises and
to determine whether exercises have the characteristics described by Dillman et al.3 As Livingston de-fines closed-chain rehabilitation exercises, the activities require a sequential combination of joint motions; the distal end of the kinetic chain meets considerable resistance (MEL or FEL conditions); and move-ment of the individual joints of the kinetic chain sequence and
transla-tion of their instant centers of rota-tion occur in a predictable manner determined by the distribution of forces throughout the chain This definition implies control by the physician or therapist of (1) extrem-ity position, (2) distal segment mo-tion and posimo-tion, (3) applicamo-tion of forces and loads, and (4) movement
of the entire extremity
Physiology and Biomechanics of Closed-Chain Rehabilitation
Most lower-extremity occupational and athletic activities involve kinetic chain activity The large majority of these activities start with the feet on the ground, which gives a base of stability, allows generation of a ground-reaction force, and initiates
a sequence of segment activity to provide optimal position and mo-tion for the distal aspect of the ter-minal segment in the chain.1,6 Force production is governed by the
“summation of speed” principle, in
Figure 1 Positioning for early-stage
lower-extremity exercises With one-leg support, notice hip-trunk extension posture The arms may be used to help balance the trunk initially.
Trang 3which the total energy or force in a
kinetic chain is summated from the
contributions of individual
seg-ments.1
Kinetic-chain segment motions
and positions are created by
mus-cle activation patterns
Length-dependent patterns operate locally
around a joint, using co-contraction
force couples to control joint
per-turbations Force-dependent
pat-terns harmonize segment motions
by operating around two or more
joints and using agonist-antagonist
force couples to generate or
trans-fer force.7 These two types of
mus-cle activations result in coordinated
segment motions that allow
kinetic-chain activity to produce the
de-sired forces needed for
occupa-tional or athletic purposes The
resultant synergistic patterns create
postural stability throughout the
entire extremity while allowing
voluntary muscle activity at the
distal segment.1,2,8 These
synergis-tic patterns include increased
acti-vation of biarticular muscles (i.e.,
hamstrings, quadriceps) by
mon-articular muscles (i.e., gluteus medius, soleus)9 and coordination
of arm and scapular movements to produce glenohumeral stability through the range of motion, al-lowing maximum arm motion.10
They are highly dependent on joint- and angle-specific proprio-ceptive feedback.11
In the leg, the hamstrings act as part of a length-dependent force cou-ple to control anterior tibial transla-tion.8 They also work as part of a force-dependent pattern to coordi-nate hip and knee motion,1stabilize the hip, and transfer loads up and down the leg.9 In the shoulder, the rotator cuff acts as part of a length-dependent force couple to increase glenohumeral concavity and com-pression,10but also works as part of
a force-dependent pattern to link trunk extension, scapular rotation, and arm internal rotation.8,10
Closed-chain exercise protocols have characteristics that simulate these biomechanical and
physiolog-ic requirements Mechanphysiolog-ically, they initiate joint movements from the
ground or a base of support, em-phasize sequential control of seg-ment position or motion, place the segments in functionally correct positions, and control the transfer of generated loads Physiologically, they utilize both length-dependent and activity-specific force-dependent activation patterns, emphasize position-specific proprioceptive feedback to initiate and control acti-vation, and can use the more versa-tile MEL configuration to achieve FEL muscle activation (Fig 2) Closed-chain exercises have also been shown to be protective for healing and repaired tissues They produce minimal translation, shear, and distraction forces due to the compressive nature of the applied load and the greater control of the resultant motions.5,6,9,12,13 This con-fers a margin of safety that allows shorter periods of complete immo-bilization, earlier initiation of reha-bilitation, and resultant “accelerated” protocols.12-14
Because closed-chain exercises emphasize and produce patterns of
Figure 2 Intermediate-stage lower-extremity exercises A, Use of a sliding board for an MEL exercise to balance the body over a moving
leg The patient slides side to side and pushes off each edge B, Use of a Fitter involves the same principles as use of a sliding board, but
there is a more unstable base due to its rounded edges, therefore presenting more of a proprioceptive challenge.
Trang 4motions and muscle activations,
they may not maximally rehabilitate
all of the individual muscles or
achieve normal motion of all of the
joints in the relevant kinetic chain
This is due to both muscle-activation
substitutions and alterations that
allow approximations of the normal
patterns and to individual
character-istics of muscle activation Some
muscles, such as the deltoid, upper
trapezius, gluteus medius, and
gas-trocnemius, are more resistant to
inhibition and alteration in injury or
fatigue situations; others, such as the
serratus anterior, lower trapezius,
supraspinatus, and vastus medialis
obliquus (VMO), are easily fatigued
and inhibited, and tend to “drop
out” from the activation patterns
Clinical examples of these
alter-ations include hip abductors and
extensors substituting for knee
ex-tensors in gait after ACL
recon-struction,15 the upper trapezius
substituting for the lower trapezius
in acromial elevation,10,16 and the
deltoid substituting for the
supra-spinatus in arm elevation In these
situations, the desired kinetic-chain
function (walking or arm elevation)
may be accomplished, but
activa-tion of important muscles is not
Rehabilitation strategies can be
developed to maximize activation
of the inhibited muscles while still
utilizing a closed-chain framework
This involves placing the extremity
in a closed-chain position,
empha-sizing the normal activation
pat-tern, and progressively
“unmask-ing” the target muscle by
eliminat-ing the substituteliminat-ing muscle This
process may be called “facilitation
of muscle activation.”
Role of Closed-Chain
Exercises in Rehabilitation
Closed-chain rehabilitation protocols
have beneficial characteristics that
are associated with functional
physi-ology and biomechanics They may
be utilized early in the rehabilitation sequence to protect the injured area and to prepare the entire kinetic chain for function They are the foun-dation for some rehabilitation pro-grams However, they must be mon-itored to ensure that all muscles are being appropriately activated These protocols can be used in both MEL and FEL configurations for knee and shoulder rehabilitation (Figs 3-7)
Different levels of exercises may be used in the early (acute or healing) phase, the intermediate (recovery) phase, and the late (functional) phase
of rehabilitation,6,7depending on the degree of tissue healing, the possible positions of the extremity, and the amount of load and the range of motion that are allowed
Knee and Leg Rehabilitation
Closed-chain rehabilitation tech-niques have been utilized to accel-erate and improve functional re-storation after ACL injury and reconstruction.12-14 These tech-niques create weight-bearing forces across the joint that increase local agonist-antagonist muscle coactiva-tion, decrease joint shear, minimize joint displacement and ACL strain, and reproduce proprioceptive stim-uli In addition, they activate the kinetic chains of weight bearing, running, and jumping This repro-duces the normal biomechanics of the entire leg, allowing hip-muscle activation to increase quadriceps and hamstring force output by transferring muscle work to these biarticular muscles9and by creating
a hip moment that is a major con-tributor to the knee moment.15 Hip-muscle activation and work output create load-absorbing capacity that can compensate for a low load-absorbing capacity in the knee so that the entire leg functions at an acceptable level early in rehabilita-tion.15 Closed-chain exercises also reproduce the physiologic length-dependent patterns for hip- and knee-joint stability, as well as
force-dependent patterns of coordination
of hip, knee, and ankle joint motion The effect that closed-chain exercises have on the entire kinetic chain is more functionally important than the effect on the knee joint alone Closed-chain techniques are also useful in rehabilitation of the patient with patellofemoral pain, largely due to the same factors of joint position control, larger im-provements in the strength of the entire kinetic chain, and alteration
of the magnitude and position of applied forces Increased total leg stiffness, with resultant knee joint control, is achieved by activating the hip muscles concurrently with the knee muscles.9,17 Closed-chain exercises have been shown to pro-duce greater improvements in quadriceps strength and leg perfor-mance than open-chain exercises.18
Closed-chain exercises produce lower patellofemoral joint stresses
in the functionally and sympto-matically important arc of motion from extension to 45 degrees of flex-ion than do open-chain exercises.19
Lower-extremity closed-chain exercises are largely FEL, with the foot on the ground in the early reha-bilitation stages Most protocols emphasize early, if not immediate, weight bearing on the affected ex-tremity The leg may be supported, but controlled range of motion and compression loading of the joint are encouraged Initially, the patient is
in a two-legged support stance, but may be moved into a one-legged support stance as healing progresses Rhythmic motion patterns of flexion/ extension and lateral movement are used Early emphasis is placed on achievement and maintenance of a position of 0 degrees of hip exten-sion and neutral pelvic tilt to allow maximum hip-muscle activation Most leg exercises should proceed from this “ideal” position
Closed chain–based protocols advocated for rehabilitation of ACL and patellofemoral injuries12-14,17
Trang 5are similar in their early stages, but
differ in the intermediate and
re-covery stages (from 3 weeks to 3
months) Common characteristics
include progressive compression
loading of the joint, controlled
increase in range of motion,
main-tenance of functional posture of the knee and leg, and emphasis on early return to functional activities, such as running, weight lifting, and mild cutting
Some of the more commonly advocated closed-chain exercises in
the intermediate and recovery stages include the two-legged squat with increasing resistance, the one-legged squat with support, and the step up–step down maneuver—all
of which are FEL exercises Exam-ples of MEL exercises include
C
Figure 3 Exercises to increase quadriceps
activation A and B, Hip extension and
foot-flat in step down–pull up exercise acti-vates the quadriceps eccentrically and con-centrically Hip control is maintained by activation of hip extensors and abductors.
Notice VMO activation in left leg C, Slant
board use in a step down–pull up exercise.
Quadriceps activation is greater D and E,
Hip extension and hip and pelvis rotation The trunk and hip are rotated around the planted leg Notice VMO activation.
Trang 6ing on a smooth surface (Fig 2, A)
or using a Fitter device (Fitter
International, Calgary, Alberta,
Canada) with a rounded-edge
sup-port surface (Fig 2, B) and
trampo-line bounding The range of
possi-ble exercises is large, and creativity
may be used to match the exercises
to the sport or activity demand
In the late stage (after 3 months),
emphasis is on functional
progres-sions and a mixture of closed- and
open-chain exercises The
closed-chain exercises for joint
coordina-tion, leg control, and resistance to
perturbation should be regarded as
a base for the open-chain exercises
of jumping rope, cutting, kicking,
leg extensions, and leg curls
Facilitation patterns to maximize
quadriceps activation and increase
knee load-bearing capacity are also
employed in the recovery and
func-tional stages of rehabilitation They
initially involve active hip extension
and quadriceps activation with the
foot flat on the floor or stepping off
a flat step (Fig 3, A and B) This FEL pattern reactivates the normal sequencing pattern for the entire leg, but probably does not maximally isolate or activate the quadriceps
The MEL equivalent, using a tram-poline, wobble board, or Fitter, adds
an element of increased propriocep-tive feedback More effecpropriocep-tive quad-riceps activation in a closed-chain exercise is accomplished by placing the foot on a slant board Ankle plantar-flexion and slight hip flex-ion decrease hip and ankle activa-tion, but slight knee flexion places more emphasis on quadriceps acti-vation as the patient executes a step up–step down maneuver (Fig 3, C)
Further quadriceps facilitation is accomplished by one-legged stance, hip extension, slight knee flexion, and hip and trunk rotation around the planted leg (Fig 3, D and E)
This FEL exercise promotes maxi-mal electromyographic activity in
the VMO The MEL equivalent uti-lizes a trampoline or wobble board
In summary, closed-chain exer-cises for knee rehabilitation allow early weight bearing, protect the injured or healing area, and prepare the entire extremity for vigorous functional open- or closed-chain athletic activities They should form the basis for most knee rehabilita-tion protocols, including those for ACL and patellofemoral injuries The exact sequence and composi-tion of the protocols may be vari-able, but limited outcomes assess-ments indicate a faster return to functional status with protocols in which these types of exercises are emphasized.12,13
Shoulder and Scapular Rehabilitation
On superficial analysis, it would appear that closed-chain rehabilita-tion would have little applicarehabilita-tion for the shoulder and arm The hand is
Figure 4 Early-stage exercises for shoulder and scapular rehabilitation A, Trunk extension and scapular retraction The arm may be
ele-vated or at the side, depending on healing Diagonal hip extension and scapular retraction can be done with either a two-legged stance
(B) or a one-legged stance One-legged stance improves hip and pelvis control Muscle activation goes from the hip through trunk
exten-sion to scapular retraction in either stance C , The modified pushup is an early-stage exercise for lower trapezius–serratus anterior
weak-ness Pushups may also be done with the hands on a table.
Trang 7obviously moving in an open-chain
fashion in throwing and serving,
and the arm assumes a
weight-bearing position only in gymnastics
and blocking in football However,
shoulder position, motion, and force
transfer fit the physiologic and
bio-mechanical requirements of
closed-chain activities In throwing and
serving, the scapula and shoulder
display intersegmental coordination,
with coupled movements that are
predictable on the basis of arm
posi-tion.8,10 The shoulder acts as a stable
funnel, transferring and regulating
forces in the kinetic chain from the
legs to the hand.1,20 The shoulder
muscles are activated in mainly
co-contraction length-dependent
pat-terns to stabilize the joint.9,10,20,21
Proprioception plays a major role in
controlling and activating muscle
patterns.11 In swimming, weight
lift-ing, and playing on the offensive or
defensive line in football, the hand
meets considerable resistance but
still moves, creating MEL conditions
at the distal end of the extremity
Closed-chain exercises should,
therefore, be utilized in shoulder
and scapula rehabilitation for
func-tional return to most athletic
activi-ties from all types of shoulder
in-juries Rehabilitation protocols for
tendinitis, postoperative instability,
and postoperative labral injuries are
basically the same in the acute
phase and in the early functional
phase.5,6 Postoperative rotator cuff
protocols should vary with the
in-tegrity of the repair, but can also
benefit from the proximal activation
and low shear characteristics Just
as in knee and leg rehabilitation,
closed-chain exercises may be used
in the early stages of rehabilitation,
and emphasis should be placed on
involving all of the joints of the
kinetic chain
Early-stage exercises involve not
only the scapula but also the hip
and trunk The large extrinsic
mus-cles of the shoulder (the latissimus
dorsi and pectoralis major) and the
muscles that position the scapula (the upper and lower trapezius and serratus anterior) are all attached to the trunk They provide key
stabili-ty and force generation to decrease shoulder load and facilitate rotator cuff activation Early in rehabilita-tion, when the shoulder muscles are weakest, facilitation needs from proximal muscle activation are at their greatest Muscle activation patterns to rehabilitate these mus-cles start with stabilization of the hip and trunk, and involve diagonal
as well as ipsilateral exercises
Diagonal activations (from left hip
to right arm and from right hip to left arm) are important to recreate the rotational activation and control patterns that are used in athletic activities such as throwing and
swimming and in daily activities such as reaching and starting a lawn mower Commonly employed exer-cises to rehabilitate these patterns include trunk extension–scapular retraction (Fig 4, A) and diagonal hip extension–scapular retraction (Fig 4, B) These exercises may be done both preoperatively and in the immediately postoperative period They involve minimal forces at the shoulder and may be done with the arm in a sling or other protective device Such exercises create a stable posture of the proximal segments that allows accelerated rehabilita-tion of the healing distal tissues Closed-chain exercises are the most effective method for rehabili-tation of the patient with scapular dyskinesis (alterations in scapular
Figure 5 Intermediate-stage scapular “clock” exercises (arrows indicate direction of
scapular motion) A and B, Elevation and depression (12- and 6-o’clock positions, respec-tively) C and D, Retraction and protraction (9- and 3-o’clock positions).
Trang 8position and motion that are
fre-quently associated with shoulder
injury and lower trapezius and
serratus anterior muscle
weak-ness).5,6,21,22 These alterations are
clinically manifested by
promi-nence of the inferior medial, entire
medial, or superior medial border
of the scapula, depending on
asso-ciated muscle weakness or
inflexi-bility
Weakness of the lower trapezius
and serratus anterior is very
com-mon, and these muscles are
fre-quently difficult to reactivate
Early-stage exercises include modified
pushups (Fig 4, C) and scapular
“pinch” retractions—exercises in
which the scapulae are retracted to
the midline These initiate scapular
control, but do not create forces that
protract the scapula or place shear
stress on the shoulder joint
Facilita-tion of lower trapezius and serratus
anterior activation can be achieved
by combined hip-trunk extension
and shoulder extension (the “low
row” exercise) This exercise may be
started in an FEL pattern, with the
hand on a wall or table, and then
changed to an MEL pattern with the hand on rubber tubing, a ball, or a movable device Decreasing hip sta-bility by standing on a wobble board
or trampoline decreases hip exten-sion and facilitates maximal lower trapezius activation
Intermediate-stage closed-chain exercises include scapular “clock”
exercises (Fig 5), in which the scapula is rotated in elevation and depression (12- and 6-o’clock posi-tions) and retraction and protraction (9- and 3-o’clock positions) Elec-tromyographic studies have demon-strated that these exercises activate scapular stabilizers at moderate lev-els, but do not create shoulder-joint shear by deltoid activation.6 These can also be done in FEL fashion, with the hand on a wall, or in MEL fashion, with the hand on a ball
Other MEL exercises include “wall washes” (Fig 6), scapular retraction and shoulder extension, military or bench presses, pushups “with a plus” (performed by arching the back and pushing out farther at the end of the pushup),23and dynamic hug exercises.24
Functional-stage closed-chain scapular exercises include higher-speed scapular protraction and retraction with weights or tubing and medicine-ball drills These MEL exercises involve hip exten-sion and trunk rotation and provide plyometric-type stretch-shortening cycles to improve power develop-ment They can be coordinated with more open-chain exercises for rapid hand velocity when appropriate Rotator cuff rehabilitation with use of closed-chain techniques
close-ly simulates normal rotator cuff function The rotator cuff functions
as a compressor cuff when the arm
is in the common athletic position of
80 to 105 degrees of elevation, and is maximally activated off a stabilized scapula.10,25 The positions advo-cated for maximal isolation of the individual rotator cuff muscles for evaluation and strengthening are not commonly seen in normal serv-ing or throwserv-ing and do not allow integration of rotator cuff function with the rest of the kinetic chain Closed-chain exercises enhance joint compression, activate scapula- and shoulder-coupled motions, control joint position, and stimulate propri-oception.3-5,10,11,24,25 Because these exercises create low levels of mus-cle activation, they are safer in the early stages of rehabilitation.6
Early-stage exercises include table pushups and humeral head depressions (Fig 7, A) When the arm can safely achieve 90 degrees of abduction, intermediate-stage activ-ities include rotator-cuff clock exer-cises, isometric humeral head de-pression with trunk extension and scapular retraction, and pushups, either modified or normal These create joint compression, work the shoulder muscles in co-contraction
at physiologic positions, and reacti-vate normal proprioceptive pat-terns.25,26 Facilitation of rotator cuff activation is achieved by trunk ex-tension and scapular retraction This allows optimal positioning of
Figure 6 “Wall washes” for scapular rehabilitation The hand slides on a
smooth-surfaced wall Trunk extension and rotation and scapular motion are emphasized.
Trang 9the muscles to generate force while
minimizing length and tension
mis-matches.10,25 Late-stage
closed-chain exercises include MEL
exer-cises, such as punches with weights
(Fig 7, B and C), standing arm
abduction with weights or tubing,
and medicine-ball drills.6,23,25,26
Summary
Closed-chain exercise protocols have
assumed a large role in functional
knee rehabilitation They have been
advocated as being safer and more
effective than previously described
protocols for both ACL12-14 and
patellofemoral17,19 rehabilitation,
although not all studies demonstrate
a clear superiority in outcomes
Closed-chain exercises are also being
employed in shoulder rehabilitation
protocols,5,6,24although no outcomes
studies have been reported
Utiliza-tion of these protocols is based on theoretical benefits and anecdotal evidence of more rapid return of shoulder function On the basis of this information, it appears that closed-chain exercises may increase the effectiveness of both knee and shoulder rehabilitation protocols
by simulating normal physiologic activations and biomechanical motions Because of the utility and increasing use of these exercises, physicians should be familiar with the underlying biomechanics and when it is appropriate to use them
They appear to be effective in the early stages of rehabilitation due to the control of joint motion and tissue loads There is no clear consensus about a particular set of exercises that should be included in every rehabilitation protocol, although both FEL and MEL exercises can be effective at different stages The major criterion for including an
exercise in a closed-chain protocol
is whether it fits the definition6and accomplishes the purposes3,5 of closed-chain activation
Closed-chain exercises and reha-bilitation protocols are not the only techniques for functional rehabilita-tion A combination of open- and closed-chain exercises will ultimately
be necessary to simulate normal functions and optimize the return to activities, especially in throwing, striking, and kicking sports.5,24 The FEL and MEL exercises provide a stable base and allow shading into MNL exercises that are truly open-chain activities
Closed-chain exercises offer great promise in making rehabilitation more efficacious Much more atten-tion should be paid to standardizing protocols, validating their direct influence on joint loads and muscle activation, and reporting outcomes studies
Figure 7 Exercises for rotator-cuff rehabilitation A, Isometric humeral head depression The resistive weight is set so that the bar does
not move The arm is pulled down with the elbow straight, so that the depression force is concentrated at the shoulder B and C, Rotator
cuff punches with weights The weight should create a load but allow the arm to be extended The exercise should start with hip and
trunk extension and scapular retraction (B) and then proceed to arm punches at different levels of arm elevation (C).
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Body Under Normal and Pathological
Conditions Springfield, Ill: Charles C
Thomas, 1955, pp 63-67.
3 Dillman CJ, Murray TA, Hintermeister
RA: Biomechanical differences of
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respect to the shoulder J Sports Rehab
1994;3:228-238.
4 Blackard DO, Jensen RL, Ebben WP:
Use of EMG analysis in challenging
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5 Lephart SM, Henry TJ: The
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6 Kibler WB, Livingston B, Bruce R:
Current concepts in shoulder
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7 Nichols TR: A biomechanical
perspec-tive on spinal mechanisms of
coordi-nated muscular action: An architecture
principle Acta Anat (Basel) 1994;151:1-13.
8 Zattara M, Bouisset S: Posturo-kinetic
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