closed-chain rehabilitation for upper and lower …...to the upper extremity. for exam-ple, a...

Journal of the American Academy of Orthopaedic Surgeons412

Orthopaedic surgeons are intimatelyinvolved in the rehabilitation pro-cess, in that they establish the ana-tomic diagnosis of the injury, deter-mine the timing of entrance into andexit from the rehabilitation program,and select the modalities and exer-cises that are used. Even though theyusually do not physically demon-strate or personally supervise theexercises, they must understand thebasic concepts underlying the vari-ous types of exercises and the timingof exercise progressions, in order toeffectively communicate with thephysical therapists and coordinatethe best program for the individualpatient’s needs.

Most current rehabilitation pro-grams emphasize functional resto-ration of the injured part, whichrequires not only repair and healingof injured tissues but also restorationof correct positioning and move-ment of joints as well as activation ofmuscles in the proper sequence so asto achieve normal function. Closed-

chain protocols have been advocatedin rehabilitation because they havecharacteristics that encourage morecomplete functional restoration. Theseexercises have been used extensivelyfor anterior cruciate ligament (ACL)injuries as a major component of“accelerated” knee rehabilitation, aswell as for rehabilitation of patientswith patellofemoral and shoulderinjuries.

Despite increasing usage, there isstill controversy about what closed-chain exercises are and how andwhen to use them. Neither is therea common understanding of whatdefines a closed-chain exercise, howclosed-chain exercises promotefunctional restoration, and what thebest closed-chain exercises are fordifferent stages of the rehabilitationprocess. To be able to appropriatelyprescribe and utilize these tech-niques, the physician must first un-derstand the underlying physiologyand biomechanics of closed-chainrehabilitation.

Definitions

The human body produces motionsand performs complex skills throughsequential activation of muscles andmovement of body segments, orlinks.1,2 This link activation, whichmay be activity- or sport-specific, istermed a “kinetic chain.” There aretwo broad-based classes of kineticchains—”open,” in which the termi-nal link of the chain is not loadedand is freely movable (mobile end,no load [MNL]), and “closed,” inwhich the terminal link is con-strained or immovable due to afixed position or large load (fixedend, external load [FEL]). The mo-tion of the foot of a kicking leg is anexample of an MNL kinetic chain.A pure FEL kinetic chain is exempli-fied by a fixed foot during a squatexercise. Force generation, forcedistribution, joint motion, muscle ac-tivation, and resultant tissue stresscan be quite different in the twoclasses.

Dr. Kibler is Medical Director, LexingtonSports Medicine Center, Lexington, Ky. Mr.Livingston is Clinical Specialist, LexingtonSports Medicine Center.

Reprint requests: Dr. Kibler, Lexington SportsMedicine Center, 1221 South Broadway,Lexington, KY 40504.

Copyright 2001 by the American Academy ofOrthopaedic Surgeons.

Abstract

Closed-chain exercise protocols are used extensively in rehabilitation of kneeinjuries and are increasingly used in rehabilitation of shoulder injuries. Theyare felt to be preferable to other exercise programs in that they simulate normalphysiologic and biomechanical functions, create little shear stress acrossinjured or healing joints, and reproduce proprioceptive stimuli. Because ofthese advantages, they may be used early in rehabilitation and have been inte-gral parts of “accelerated” rehabilitation programs. The authors review theimportant components of a closed-chain rehabilitation program and provideexamples of specific exercises that are used for rehabilitation of knee and shoul-der injuries.

J Am Acad Orthop Surg 2001;9:412-421

Closed-Chain Rehabilitation for Upper and Lower Extremities

W. Ben Kibler, MD, and Beven Livingston, MS, PT


Vol 9, No 6, November/December 2001 413

Steindler2 was the first to de-scribe the differences in muscleactivation and joint motion thatoccur when the distal end of thearm or leg in a kinetic chain meetsconsiderable resistance comparedwith when it is freely movable. Hisdefinition of a closed-chain condi-tion required that the foot or handmeet enough resistance to prohibitor restrain its free motion, and thatthe resultant extremity muscle acti-vation was sequential from distalto proximal in the extremity.

Physical therapy protocols havebeen developed to take advantageof the force-generation and loadingcharacteristics of closed-chain exer-cises. There has been wide varietyin their application, but in general,closed-chain protocols include aprogression of exercises that arebased on application of a load to thedistal end of an extremity that doesnot move freely due to either posi-tioning (e.g., on a wall or on theground [Fig. 1]) or the load charac-teristics (e.g., axially applied heavyload). Subsequent joint motion takesplace in multiple planes while thelimb is supporting weight. Theseconditions differentiate these exer-cises from “open chain” exercises,such as knee extensions, trunk ex-tensions against gravity, and isolatedrotator cuff exercises with tubing orweights.

Dillman et al3 described condi-tions that define closed-chain exer-cises. They realized that the effectof the exercise on joint positionsand muscle activations is the criticalpoint in defining a closed-chainexercise. They felt that closed-chainexercises have to include relativelysmall joint movements, low jointaccelerations, large resistanceforces, joint compression, decreasedjoint shear, stimulation of joint pro-prioception, and enhanced dynamicstabilization through muscle coac-tivation. They also recognized thatthe amount of load at the terminalend 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 largeenough load can still create physio-logic conditions that replicateclosed-chain characteristics. Thisenlarged the concept of a closed-chain exercise from being only anFEL activity to include mobileend–external load (MEL) activitiesas well, making it more applicableto the upper extremity. For exam-ple, a military press (an MEL exer-cise) can have closed-chain effectssimilar to those of a pushup (anFEL exercise). This concept hasbeen validated by Blackard et al,4who found that there was no differ-ence in muscle activation betweenequivalently loaded upper-extremityexercises with either fixed or mobileends. They concluded that externalloading characteristics were moreimportant than arm motion in de-scribing and simulating humanactivity.

Lephart and Henry5 modified theMEL condition to include two differ-ent external load conditions—axialload (e.g., military press) and rotaryload (e.g., arm rotations with dumb-bells). This helped to define types ofexercises but did not change the con-cept that closed-chain joint loadingand muscle activation characteristicscan be obtained with a movable dis-tal end. However, it enlarged thescope of the types of exercises thatcan be employed in a closed-chainrehabilitation program.

Livingston6 developed an opera-tional definition to guide implemen-tation of closed-chain exercises andto determine whether exercises havethe characteristics described byDillman et al.3 As Livingston de-fines closed-chain rehabilitationexercises, the activities require asequential combination of jointmotions; the distal end of the kineticchain meets considerable resistance(MEL or FEL conditions); and move-ment of the individual joints of thekinetic chain sequence and transla-

tion of their instant centers of rota-tion occur in a predictable mannerdetermined by the distribution offorces throughout the chain. Thisdefinition implies control by thephysician or therapist of (1) extrem-ity position, (2) distal segment mo-tion and position, (3) application offorces and loads, and (4) movementof the entire extremity.

Physiology andBiomechanics of Closed-Chain Rehabilitation

Most lower-extremity occupationaland athletic activities involve kineticchain activity. The large majority ofthese activities start with the feet onthe ground, which gives a base ofstability, allows generation of aground-reaction force, and initiatesa sequence of segment activity toprovide optimal position and mo-tion for the distal aspect of the ter-minal segment in the chain.1,6 Forceproduction 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. Thearms may be used to help balance thetrunk initially.

Closed-Chain Rehabilitation


which the total energy or force in akinetic chain is summated from thecontributions of individual seg-ments.1

Kinetic-chain segment motionsand positions are created by mus-cle activation patterns. Length-dependent patterns operate locallyaround a joint, using co-contractionforce couples to control joint per-turbations. Force-dependent pat-terns harmonize segment motionsby operating around two or morejoints and using agonist-antagonistforce couples to generate or trans-fer force.7 These two types of mus-cle activations result in coordinatedsegment motions that allow kinetic-chain activity to produce the de-sired forces needed for occupa-tional or athletic purposes. Theresultant synergistic patterns createpostural stability throughout theentire extremity while allowingvoluntary muscle activity at thedistal 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., gluteusmedius, soleus)9 and coordinationof arm and scapular movements toproduce glenohumeral stabilitythrough the range of motion, al-lowing maximum arm motion.10

They are highly dependent onjoint- and angle-specific proprio-ceptive feedback.11

In the leg, the hamstrings act aspart of a length-dependent force cou-ple to control anterior tibial transla-tion.8 They also work as part of aforce-dependent pattern to coordi-nate hip and knee motion,1 stabilizethe hip, and transfer loads up anddown the leg.9 In the shoulder, therotator cuff acts as part of a length-dependent force couple to increaseglenohumeral concavity and com-pression,10 but also works as part ofa force-dependent pattern to linktrunk extension, scapular rotation,and arm internal rotation.8,10

Closed-chain exercise protocolshave characteristics that simulatethese biomechanical and physiolog-ic requirements. Mechanically, theyinitiate joint movements from the

ground or a base of support, em-phasize sequential control of seg-ment position or motion, place thesegments in functionally correctpositions, and control the transfer ofgenerated loads. Physiologically, theyutilize both length-dependent andactivity-specific force-dependentactivation patterns, emphasize position-specific proprioceptivefeedback to initiate and control acti-vation, and can use the more versa-tile MEL configuration to achieveFEL muscle activation (Fig. 2).

Closed-chain exercises have alsobeen shown to be protective forhealing and repaired tissues. Theyproduce minimal translation, shear,and distraction forces due to thecompressive nature of the appliedload and the greater control of theresultant motions.5,6,9,12,13 This con-fers a margin of safety that allowsshorter periods of complete immo-bilization, earlier initiation of reha-bilitation, and resultant “accelerated”protocols.12-14

Because closed-chain exercisesemphasize and produce patterns of

A B

Figure 2 Intermediate-stage lower-extremity exercises. A, Use of a sliding board for an MEL exercise to balance the body over a movingleg. 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, butthere is a more unstable base due to its rounded edges, therefore presenting more of a proprioceptive challenge.



motions and muscle activations,they may not maximally rehabilitateall of the individual muscles orachieve normal motion of all of thejoints in the relevant kinetic chain.This is due to both muscle-activationsubstitutions and alterations thatallow approximations of the normalpatterns and to individual character-istics of muscle activation. Somemuscles, such as the deltoid, uppertrapezius, gluteus medius, and gas-trocnemius, are more resistant toinhibition and alteration in injury orfatigue situations; others, such as theserratus anterior, lower trapezius,supraspinatus, and vastus medialisobliquus (VMO), are easily fatiguedand inhibited, and tend to “dropout” from the activation patterns.

Clinical examples of these alter-ations include hip abductors andextensors substituting for knee ex-tensors in gait after ACL recon-struction,15 the upper trapeziussubstituting for the lower trapeziusin acromial elevation,10,16 and thedeltoid substituting for the supra-spinatus in arm elevation. In thesesituations, the desired kinetic-chainfunction (walking or arm elevation)may be accomplished, but activa-tion of important muscles is not.

Rehabilitation strategies can bedeveloped to maximize activationof the inhibited muscles while stillutilizing a closed-chain framework.This involves placing the extremityin a closed-chain position, empha-sizing the normal activation pat-tern, and progressively “unmask-ing” the target muscle by eliminat-ing the substituting muscle. Thisprocess may be called “facilitationof muscle activation.”

Role of Closed-ChainExercises in Rehabilitation

Closed-chain rehabilitation protocolshave beneficial characteristics thatare associated with functional physi-ology and biomechanics. They may

be utilized early in the rehabilitationsequence to protect the injured areaand to prepare the entire kineticchain for function. They are the foun-dation for some rehabilitation pro-grams. However, they must be mon-itored to ensure that all muscles arebeing appropriately activated. Theseprotocols can be used in both MELand FEL configurations for knee andshoulder rehabilitation (Figs. 3-7).Different levels of exercises may beused in the early (acute or healing)phase, the intermediate (recovery)phase, and the late (functional) phaseof rehabilitation,6,7 depending on thedegree of tissue healing, the possiblepositions of the extremity, and theamount of load and the range ofmotion that are allowed.

Knee and Leg RehabilitationClosed-chain rehabilitation tech-

niques have been utilized to accel-erate and improve functional re-storation after ACL injury andreconstruction.12-14 These tech-niques create weight-bearing forcesacross the joint that increase localagonist-antagonist muscle coactiva-tion, decrease joint shear, minimizejoint displacement and ACL strain,and reproduce proprioceptive stim-uli. In addition, they activate thekinetic chains of weight bearing,running, and jumping. This repro-duces the normal biomechanics ofthe entire leg, allowing hip-muscleactivation to increase quadricepsand hamstring force output bytransferring muscle work to thesebiarticular muscles9 and by creatinga hip moment that is a major con-tributor to the knee moment.15 Hip-muscle activation and work outputcreate load-absorbing capacity thatcan compensate for a low load-absorbing capacity in the knee sothat the entire leg functions at anacceptable level early in rehabilita-tion.15 Closed-chain exercises alsoreproduce the physiologic length-dependent patterns for hip- andknee-joint stability, as well as force-

dependent patterns of coordinationof hip, knee, and ankle joint motion.The effect that closed-chain exerciseshave on the entire kinetic chain ismore functionally important thanthe effect on the knee joint alone.

Closed-chain techniques are alsouseful in rehabilitation of thepatient with patellofemoral pain,largely due to the same factors ofjoint position control, larger im-provements in the strength of theentire kinetic chain, and alterationof the magnitude and position ofapplied forces. Increased total legstiffness, with resultant knee jointcontrol, is achieved by activatingthe hip muscles concurrently withthe knee muscles.9,17 Closed-chainexercises have been shown to pro-duce greater improvements inquadriceps strength and leg perfor-mance than open-chain exercises.18

Closed-chain exercises producelower patellofemoral joint stressesin the functionally and sympto-matically important arc of motionfrom extension to 45 degrees of flex-ion than do open-chain exercises.19

Lower-extremity closed-chainexercises are largely FEL, with thefoot on the ground in the early reha-bilitation stages. Most protocolsemphasize early, if not immediate,weight bearing on the affected ex-tremity. The leg may be supported,but controlled range of motion andcompression loading of the joint areencouraged. Initially, the patient isin a two-legged support stance, butmay be moved into a one-leggedsupport stance as healing progresses.Rhythmic motion patterns of flexion/extension and lateral movement areused. Early emphasis is placed onachievement and maintenance of aposition of 0 degrees of hip exten-sion and neutral pelvic tilt to allowmaximum hip-muscle activation.Most leg exercises should proceedfrom this “ideal” position.

Closed chain–based protocolsadvocated for rehabilitation of ACLand patellofemoral injuries12-14,17



are similar in their early stages, butdiffer in the intermediate and re-covery stages (from 3 weeks to 3months). Common characteristicsinclude progressive compressionloading of the joint, controlledincrease in range of motion, main-

tenance of functional posture of theknee and leg, and emphasis onearly return to functional activities,such as running, weight lifting, andmild cutting.

Some of the more commonlyadvocated closed-chain exercises in

the intermediate and recoverystages include the two-legged squatwith increasing resistance, the one-legged squat with support, and thestep up–step down maneuver—allof which are FEL exercises. Exam-ples of MEL exercises include slid-

A B

D E

C

Figure 3 Exercises to increase quadricepsactivation. A and B, Hip extension andfoot-flat in step down–pull up exercise acti-vates the quadriceps eccentrically and con-centrically. Hip control is maintained byactivation of hip extensors and abductors.Notice VMO activation in left leg. C, Slantboard 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 theplanted leg. Notice VMO activation.



ing on a smooth surface (Fig. 2, A)or using a Fitter device (FitterInternational, 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 creativitymay be used to match the exercisesto the sport or activity demand.

In the late stage (after 3 months),emphasis is on functional progres-sions and a mixture of closed- andopen-chain exercises. The closed-chain exercises for joint coordina-tion, leg control, and resistance toperturbation should be regarded asa base for the open-chain exercisesof jumping rope, cutting, kicking,leg extensions, and leg curls.

Facilitation patterns to maximizequadriceps activation and increaseknee load-bearing capacity are alsoemployed in the recovery and func-tional stages of rehabilitation. Theyinitially involve active hip extensionand quadriceps activation with the

foot flat on the floor or stepping offa flat step (Fig. 3, A and B). ThisFEL pattern reactivates the normalsequencing pattern for the entireleg, but probably does not maximallyisolate or activate the quadriceps.The MEL equivalent, using a tram-poline, wobble board, or Fitter, addsan element of increased propriocep-tive feedback. More effective quad-riceps activation in a closed-chainexercise is accomplished by placingthe foot on a slant board. Ankleplantar-flexion and slight hip flex-ion decrease hip and ankle activa-tion, but slight knee flexion placesmore emphasis on quadriceps acti-vation as the patient executes a stepup–step down maneuver (Fig. 3, C).Further quadriceps facilitation isaccomplished by one-legged stance,hip extension, slight knee flexion,and hip and trunk rotation aroundthe 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 allowearly weight bearing, protect theinjured or healing area, and preparethe entire extremity for vigorousfunctional open- or closed-chainathletic activities. They should formthe basis for most knee rehabilita-tion protocols, including those forACL 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 tofunctional status with protocols inwhich these types of exercises areemphasized.12,13

Shoulder and ScapularRehabilitation

On superficial analysis, it wouldappear that closed-chain rehabilita-tion would have little application forthe shoulder and arm. The hand is

A B C

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.



obviously moving in an open-chainfashion in throwing and serving,and the arm assumes a weight-bearing position only in gymnasticsand blocking in football. However,shoulder position, motion, and forcetransfer fit the physiologic and bio-mechanical requirements of closed-chain activities. In throwing andserving, the scapula and shoulderdisplay intersegmental coordination,with coupled movements that arepredictable on the basis of arm posi-tion.8,10 The shoulder acts as a stablefunnel, transferring and regulatingforces in the kinetic chain from thelegs to the hand.1,20 The shouldermuscles are activated in mainly co-contraction length-dependent pat-terns to stabilize the joint.9,10,20,21

Proprioception plays a major role incontrolling and activating musclepatterns.11 In swimming, weight lift-ing, and playing on the offensive ordefensive line in football, the handmeets considerable resistance butstill moves, creating MEL conditionsat the distal end of the extremity.

Closed-chain exercises should,therefore, be utilized in shoulderand scapula rehabilitation for func-tional return to most athletic activi-ties from all types of shoulder in-juries. Rehabilitation protocols fortendinitis, postoperative instability,and postoperative labral injuries arebasically the same in the acutephase and in the early functionalphase.5,6 Postoperative rotator cuffprotocols should vary with the in-tegrity of the repair, but can alsobenefit from the proximal activationand low shear characteristics. Justas in knee and leg rehabilitation,closed-chain exercises may be usedin the early stages of rehabilitation,and emphasis should be placed oninvolving all of the joints of thekinetic chain.

Early-stage exercises involve notonly the scapula but also the hipand trunk. The large extrinsic mus-cles of the shoulder (the latissimusdorsi and pectoralis major) and the

muscles that position the scapula(the upper and lower trapezius andserratus anterior) are all attached tothe trunk. They provide key stabili-ty and force generation to decreaseshoulder load and facilitate rotatorcuff activation. Early in rehabilita-tion, when the shoulder muscles areweakest, facilitation needs fromproximal muscle activation are attheir greatest. Muscle activationpatterns to rehabilitate these mus-cles start with stabilization of thehip and trunk, and involve diagonalas well as ipsilateral exercises.Diagonal activations (from left hipto right arm and from right hip toleft arm) are important to recreatethe rotational activation and controlpatterns that are used in athleticactivities such as throwing and

swimming and in daily activitiessuch as reaching and starting a lawnmower. Commonly employed exer-cises to rehabilitate these patternsinclude trunk extension–scapularretraction (Fig. 4, A) and diagonalhip extension–scapular retraction(Fig. 4, B). These exercises may bedone both preoperatively and in theimmediately postoperative period.They involve minimal forces at theshoulder and may be done with thearm in a sling or other protectivedevice. Such exercises create a stableposture of the proximal segmentsthat allows accelerated rehabilita-tion of the healing distal tissues.

Closed-chain exercises are themost effective method for rehabili-tation of the patient with scapulardyskinesis (alterations in scapular

A B

C D

Figure 5 Intermediate-stage scapular “clock” exercises (arrows indicate direction ofscapular 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).

closed-chain rehabilitation for upper and lower …...to the upper extremity. for exam-ple, a...

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