Allograft Acl 2012

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196 | march 2012 | volume 42 | number 3 | journal of orthopaedic & sports physical therapy

[ CLINICAL COMMENTARY ]

The anterior cruciate ligament (ACL) plays an important rolein the maintenance of knee stability. If left untreated, thenatural history of an ACL-decient knee can result in recurrentinstability, inability to return to full athletic activity, meniscal

tears, and articular cartilage damage. 27 Therefore, the goals of ACLreconstruction (ACL-R) are to re-establish the form and function ofthe native ACL, restore knee stability, allow return to the preinjury

activity level, and preserve the long-termhealth of the knee. Despite adherenceto strict surgical principles, the inabilityto predict long-term articular cartilagedegeneration after ACL-R has raised

questions about the choices of surgicaltechnique, xation, graft type (various au-tografts versus allografts), and rehabili-tation. 10 Although ACL-R is a frequentlyresearched topic in sports medicine,signicant disagreement exists on theappropriate management of the torn ACL. 28 The following clinical commen-

SYNOPSIS: The anterior cruciate ligament(ACL) is an important stabilizer of the knee againsttranslational and rotational forces. The goal of

anatomic reconstruction of the ACL-decientknee is to re-create a stable knee that will allowfor return to sport and prevent recurrent injury.Multiple graft options exist for ACL reconstruc-tion, and each option has unique advantages anddisadvantages. With appropriate patient selection,each graft can be utilized to optimize patient out-comes. Allograft options limit morbidity followingACL reconstruction, but care must be taken with

surgical technique and postoperative rehabilitationto allow for graft incorporation. An understandingof the surgical technique and differences between

graft options will allow the patient, surgeon, andphysical therapist to maximize outcomes followingACL reconstruction.

LEVEL OF EVIDENCE: Therapy, level 5.JOrthop Sports Phys Ther 2012;42(3):196-207, Epub 25 January 2012. doi:10.2519/jospt.2012.4083

KEY WORDS: ACL, grafts, medial portaltechnique, surgery

1Orthopaedic Surgeon, UPMC Center for Sports Medicine, Department of Orthopaedic Surgery, Pittsburgh, PA. Dr Christopher Harner is a consultant for Smith & Nephew Inc anDepuy Mitek, Inc. Address correspondence to Dr Stephen J. Rabuck, 3200 South Water Street, Pittsburgh, PA 15203. E-mail: [email protected]

DHARMESH VYAS,MD, PhD1 STEPHEN J. RABUCK,MD1 CHRISTOPHER D. HARNER,MD1

Allograft Anterior CruciateLigament Reconstruction: Indications,

Techniques, and Outcomes

tary discusses the factors affecting graftselection, with emphasis on indicationsand the technique of allograft ACL-R, as

well as the rehabilitation and outcomesspecic to this surgical approach.

PATIENT SELECTION

Acomprehensive history andphysical exam are critical for se-lecting patients for ACL-R, as well

as for choosing the optimal graft. Thisincludes demonstration of ACL insuf-

ciency and assessment of the patientsactivity level, expectations, associated

injuries, and medical comorbidities. Sur-gical indications are based on 3 majorcriteria: the severity of perceived instability, associated knee injuries (meniscusor multiple ligaments), and chronicity ofthe ACL insufficiency.

Prior to surgical intervention on anacute ACL tear, the patient is treated withphysical therapy, with the goals of achiev-ing near full range of motion (ROM),symmetric quadriceps strength, and adecrease in joint effusion. Generally,

most patients meet these criteria within3 to 4 weeks. Contraindications to ACL-Rinclude (1) partial tears with minimal re-ported instability and no joint laxity on ex-amination, (2) older individuals with lowphysical demands and minimal instability,and (3) comorbidities that make surgicalintervention unsafe for the patient.

PREOPERATIVE (DIAGNOSTICIMAGING

Radiographs

Diagnostic imaging begins withplain radiographs. At our insti-tution, we routinely obtain a 45

exion, weight-bearing posteroanteriorradiograph of both knees and lateral andMerchant views of the patella. These ra-diographs help identify associated frac-tures (avulsion, plateau, or subchondral
mailto:[email protected]:[email protected]


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journal of orthopaedic & sports physical therapy | volume 42 | number 3 | march 2012 | 197

impaction), gauge the amount of jointspace narrowing in the 3 compartments,and assess patellar height (lateral view),tilt, and subluxation (Merchant view). Along-cassette anteroposterior view of the bilateral lower extremity is obtained todetermine overall limb alignment. Im-portantly, radiographs are a prerequisiteto assess the status of the growth plate inpediatric patients.

Magnetic Resonance Imaging

If a patients history and physical examsuggest an ACL tear, then noncontrastmagnetic resonance imaging of the kneeis obtained ( FIGURE 1). Discontinuity of the ACL in the coronal and sagittal planes isa reliable indication of an ACL tear. Inaddition, magnetic resonance imaginghelps to identify associated injuries suchas meniscal tears, chondral damage (in-cluding bone bruises), and concomitantligament injuries (posterior cruciateligament, medial and lateral collateral

ligaments, and posterolateral corner). Allograft reconstructions may be ben-ecial for multiligament injuries, as theydecrease operative time and minimize theassociated morbidity of graft harvesting.

PREOPERATIVEREHABILITATION

Rupture of the ACL results insignicant hemarthrosis, which mayaffect outcomes following ACL-R.

Large effusions can result in quadricepsinhibition. In patients with an ACL-de-cient knee, the role of the quadriceps asa dynamic stabilizer of the knee should

not be underestimated. The return ofquadriceps function and a reduction ineffusion are among the primary goals ofpreoperative rehabilitation. Inadequatequadriceps strength has been shown toproduce altered gait patterns following

ACL-R 26 and an increase in the transferof forces across the reconstructed ACL.

One of the early pitfalls of arthroscop-ically assisted ACL-R was the develop-ment of postoperative stiffness. Thiscomplication was largely attributed to

poor preoperative ROM and early sur-gical intervention during the inamma-tory phase of healing. 18,44,45 More recentstudies have shown early surgical inter-

vention to be safe, 3,9,20 with the best in-dicator of postoperative ROM loss beingthe patients preoperative ROM. 30 Pa-tients should be carefully evaluated forpreoperative ROM decits and aggres-sively treated to prevent postoperativecomplications. The patient is ready forsurgery once the inammatory period

has resolved. This period may last 2 to 3 weeks and corresponds to a decrease ineffusion and a resultant increase in ROM.Flexion must be adequate enough to al-

low for knee hyperexion during ACL re-construction. Depending on concomitantpathology, surgery may be performedearly (eg, displaced bucket-handle menis-cus tears) or may be delayed (eg, medialcollateral ligament disruption).

GRAFT SELECTION

Principles of Graft Selection

Successful ACL-R depends onseveral factors, including stable x-

ation, biological graft-bone integra-tion, adequate graft strength, and, mostimportantly, anatomic positioning. Ac-cordingly, graft selection is a very impor-tant part of preoperative planning anddepends on several factors: the patientspreference, age, activity level, and physi-cal requirements; expected outcomes;the time line for return to play; associatedligamentous injuries; medical comorbidi-ties; previous surgery; tissue availability;and surgeon preference and experience.

TABLE 1Comparison of the Advantages

and Disadvantages of Graf t Options

Graft Type Advantages Disadvantages

Allograft, bone-tendon Bone-to-bone healing

Decreased surgical time

Predictable graft size

Availability

Cost

Infectious disease transmission

Risk of bridging physis

Higher failure rate

Delayed incorporation

Allograft, soft tissue Decreased surgical time

Predictable graft size

Availability

Less risk with bridging physis

Cost

Infectious disease transmission

Higher failure rate

Delayed incorporation

Autograft, bone-tendon Faster incorporation and healing

Better outcomes in young, active patients

Prolonged surgical time

Donor site morbidity (anterior knee pain)

Risk of bridging physis

Risk of fracture

Autograft, soft tissue Faster incorporation and healing

Better outcomes in young, active patients

Less risk with bridging physis

Prolonged surgical time

Donor site morbidity (knee exion

weakness)

Unpredictable graft size

Compromise of medial structures

FIGURE 1.Sagittal magnetic resonance imagingdemonstrating anterior cruciate ligament rupture.


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[ CLINICAL COMMENTARY ] Whereas signicant debate still existsregarding the best graft choice, what is widely accepted is that the ideal graftshould reect the anatomy and biome-

chanics of the native ACL, minimize harvest site morbidity, be amenable to stablexation, and result in rapid remodelingand incorporation into the reconstructedknee. As such, graft selection is a trade-off between the benets and potentialmorbidity of each graft ( TABLE 1).

Graft TypesGraft sources for ACL-R fall into 3 majorcategories: synthetic/articial ligaments,autografts, and allografts. Synthetic

grafts such as scaffolds (carbon ber) andstents (Kennedy ligament augmentationdevice), and prostheses such as polytetra-uoroethylene Gore-Tex (W.L. Gore & As-sociates, Inc, Elkton, MD), polyethyleneterephthalate (Leeds-Keio articial liga-ment), and Dacron (Invista, Wichita, KS),have demonstrated poor clinical resultssecondary to loosening, fatigue failure,and a strong host immune response. 29,43,58 Commonly used autografts include thecentral third of the patellar tendon,

hamstring tendons (semitendinosus andgracilis), and the quadriceps tendon.Several allograft options are availableas well. These can be divided into graftsproviding bone-to-bone healing andgrafts consisting solely of soft tissue. Thepatellar-tendon allograft is the only op-tion for proximal and distal osseous inte-gration. Achilles tendon and quadricepstendon allografts contain a single osseousattachment. Soft tissue allografts includethe hamstring, tibialis anterior, tibialis

posterior, and peroneus longus tendons,as well as the tensor fascia lata. Allograft Advantages/Disadvantages All graft types offer distinct advantagesand disadvantages to the patient and thesurgeon. The benets of allograft use in-clude absence of donor site morbidity,shortened operating time, availability forcomplex cases (multiligament knee andrevision ACL-R), greater availability andmore predictable graft sizes, and compa-rable strength and stiffness to autograft

tissue at the time of reconstruction. 4,35,38,52

Signicant disadvantages of allograft tis-sue are potentially higher failure rates,increased time to incorporation, vari-ability in mechanical strength due to sec-ondary sterilization techniques, risk ofdisease transmission, immunogenic reac-tion, lack of long-term outcome data (es-pecially for young patients under the ageof 25), and higher cost. 31,46,58 The seniorauthors (C.D.H.) preferred technique isanatomic single-bundle ACL-R using a bone-patellar tendon-bone autograft.

INDICATIONS FOR ALLOGRAFTACL RECONSTRUCTION

In the senior authors (C.D.H.) prac-tice, the graft choice for each ACL-Ris tailored to suit the individual pa-

tient. We routinely utilize multiple graftchoices, with approximately 80% of them being autografts (70% bone-patellar ten-don-bone and 30% hamstring) and 20%allografts (100% bone-patellar tendon-

bone). Generally, allograft tissue is re-served for patients older than 40 years.In this population, the autograft benetsof more rapid incorporation and healingdo not appear to warrant the increasedmorbidity from harvesting a graft fromthe patient. Allograft tissue is only usedin special circumstances for patients whoare 12 to 30 years old, and autografts arealso strongly recommended for patients who are 30 to 40 years old. The ideal can-didate for an allograft at our center is a

mildly to moderately active patient older

than 40 years who experiences symptom-atic instability during activities of dailyliving and whose clinical presentation isconsistent with ACL rupture. Other in-dications for use of allograft tissue arereconstruction of multiligament knee injuries, revision ACL-R, cases where au-tograft tissue is inadequate, and patientpreference ( TABLE 2).1,41,42

TECHNIQUE FOR MEDIALPORTAL ACL-R

We provide a brief descriptionof our technique for anatomic ACL-R using the medial portal

for femoral tunnel drilling. We aim foranatomic placement of the femoral andtibial tunnels. Femoral tunnel placementis done via the medial portal, allow-ing placement independent of the tibialtunnel (the transtibial technique). Thistechnique may be utilized in all cases ofprimary (single-bundle, double-bundle,

or augmentation) or revision ACL-R, andis not dependent on the choice of graft,instrumentation, or nal xation.

Portals and IncisionsDuring the procedure, we utilize 3 portals(FIGURE 2): anterolateral (viewing), an-teromedial (working), and superolateral(outow). The medial portal is made un-der direct arthroscopic visualization us-ing a spinal needle. This is done not onlyto avoid damaging the medial meniscus

TABLE 2 A Summary of the Relat ive

Indications for Allograft AnteriorCruciate Ligament Reconstruction

Abbreviation: ACL-R, anterior cruciate ligament reconstruction.* It is the authors preference to use an autograft in revision cases if that graft has not been harvested in previous surgery and if the patient meets criteria for autograft use (ie, age, activity level).

Most Common Indications for Allograft ACL-R

Patients older than 40 y

Multiple ligament knee injuries

Prior harvest from donor sites

Patient preference

Revision ACL-R*


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but also to allow adequate clearance fromthe medial femoral condyle. When usingallograft tissue, a 3-cm vertical incisionis made on the anteromedial aspect ofthe tibia for drilling the tibial tunnellater in the procedure. The location of

this incision is estimated by provisionalplacement of the tibial tunnel ACL guidemidway between the anterior and poste-rior borders of the tibia.

Allograft PreparationBone-Patellar Tendon-Bone Our prefer-ence is for the bone-patellar tendon-boneallograft ( FIGURE 3). The central 10 mmof the patellar tendon is utilized, with bone plugs measuring 20 mm in length both proximally and distally. The plugs

are designed to be trapezoidal in shape,and the leading plug is tapered to facili-tate graft passage. Two 1.5-mm holes aredrilled in the tibial bone plug and a num-

ber 5 Ethibond (braided, nonabsorbable;Ethicon, Inc, Somerville, NJ) is threadedthrough the holes. These will be used tosecure nal plug xation over a post. The

femoral bone plug is secured using theEndoButton CL (Smith & Nephew Inc,Memphis, TN) device to provide suspen-sory xation ( FIGURE 4).Soft Tissue In certain cases, a soft tissueallograft is used. This graft is generallydoubled over to increase its diameter. It isimportant to pay careful attention to thenecessary diameter of the graft because di-mensions may not be consistent through-out the entire length of the graft. The goalis to prepare an appropriately sized graft

with consistent dimensions and adequatelength for ACL-R. We use an EndoButtonCL device, over which the graft is doubled. A suture is tied within the proximal por-

tion of the graft, and a second nonabsorb-able suture is secured within the distalportion of the graft to be tied around apost for tibial xation ( FIGURE 4).

Arthroscopic ACL-RThe fat pad is left intact to prevent post-operative scarring, patellar entrapment,and pain. Assessment of any associatedintra-articular pathology is performed before preparation of the femoral andtibial insertion sites. On the femoral

side, using the location of the torn ACLremnant as a guide ( FIGURE 5), we markthe center of the anatomic ACL insertionsite with a 30 Steadman awl ( FIGURES 6Aand 6B). On the tibial side, a signicantportion of the ACL stump is preservedto enhance proprioceptive and vascularproperties. 25 We do not routinely performa notchplasty unless it is needed for bet-ter visualization (1-2 mm) or to alleviategraft impingement.Femoral Tunnel Placement The native

ACL footprint, although variable in eachindividual, is generally 4 to 6 mm ante-rior to the posterior femoral cortex withthe knee at 90 of exion. Appropriatetunnel position is further conrmed viaintraoperative uoroscopy by taking alateral image of the knee (90 of exionand overlapping condyles) with the awlstill in position ( FIGURE 6C). With the kneehyperexed, a guide pin is placed in theanatomic footprint ( FIGURE 7A) and anacorn reamer is carefully advanced over

the guide wire to avoid damaging thecartilage of the medial femoral condyle(FIGURE 7B). Finally, a 3.2-mm EndoBut-ton drill is used to breach the lateralfemoral cortex.Tibial Tunnel Placement Anatomic tibialtunnel position is also accomplished us-ing a combination of visual arthroscopiclandmarks ( FIGURE 8) and uoroscopic im-aging ( FIGURE 9). An ACL elbow-tip guideis set at 50 to 55 and placed at the inter-section between the posterior edge of the

FIGURE 2.Incisions for allograft anterior cruciateligament reconstruction. Anterolateral viewing portal,anteromedial working portal, and superolateraloutow portal. A medial tibial incision is used for

tibial tunnel placement and graft passage.

FIGURE 3.Bone-patellar tendon-bone allograft priorto (A) and following (B) graft preparation.

FIGURE 4.Posterior tibialis allograft prior to (A) andfollowing (B) graft preparation.

FIGURE 5.Arthroscopic image of anterior cruciateligament rupture.


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anterior horn of the lateral meniscus andthe midline of the tibial spines. Verica-tion of the Kirschner wire placement isdone with arthroscopy and uoroscopy. After correct placement of the guide pin,a cannulated compaction reamer is usedover the Kirschner wire.Graft Passage Using passing sutures, thegraft is advanced up the tibial tunnel andthe tendinous portion of the bone-patel-lar tendon-bone allograft is maintained in

the posterior aspect of both tunnels ( FIG-URE 10). After clearing the lateral femoralcortex with the EndoButton, the device istoggled to engage the cortex and preventpassage back into the tunnel. Tension isapplied to the tibial sutures, and the kneeis cycled to minimize graft creep. Graftisometry and impingement are checked.

Graft FixationMultiple options exist for graft xation.These options include tying over a post,

suspensory xation, and interferencescrews, and are dependent to some extenton the type of graft chosen (ie, bone blockor soft tissue alone). Our choice for tibialxation is tying over a post (4.5-mm AOfully threaded cortical screw over a washer, bicortical purchase). After the far cortex isengaged but before nal seating, the tibialsutures are individually tied around thepost. The screw-and-washer constructis then fully tightened and the Lachmanand pivot shift tests are performed for -

nal verication of graft tension. We prefer

suspensory and suture/post xation with bone plugs to allow for maximal healing between the graft and host bone ( FIGURE 11).

There are many benets to perform-ing xation in this manner. The tunnelsin the above technique are dilated to ex-actly t the graft, providing circumfer-ential interaction between the graft andapposed bone within the tunnel. Thereis no xation device within the tunnelto interfere with graft healing or theinteraction of the graft with potentially

benecial growth factors. Lastly, shouldrevision surgery be required, the retainedhardware will not limit surgical options.

POSTOPERATIVEREHABILITATION ANDRETURN TO PLAY

ROM and Strengthening

Rehabilitation following ACL-Rshould follow a logical progressionthat allows for progressive strength-

FIGURE 6.The anatomic femoral insertion isidentied during arthroscopy (A and B). The plannedtunnel placement is conrmed with uoroscopy (C).

FIGURE 7.Femoral tunnel placement. With theknee hyperexed, a guide pin is placed in theanatomic footprint of the anterior cruciate ligamenton the medial wall of the lateral femoral condyle(A). Arthroscopic view of guide wire placement inanatomic footprint (B).

FIGURE 8.The tibial guide is placed in the anatomicfootprint for passage of the tibial guide pin.


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ening and protection of the reconstructed ACL. Following ACL-R, the overall goalsof rehabilitation are to minimize in-ammation, to restore knee motion andquadriceps strength, to enhance pro-prioception, neuromuscular control, anddynamic joint stability, and to ensure areturn to sport-specic activities.

During the initial postoperative pe-riod, guarded ROM exercises help to

initiate the processes of healing andstrengthening. For the rst week aftersurgery, the patients are asked to bear weight with crutches and a knee bracelocked in full extension. Basic home ex-ercises include quadriceps sets, straightleg raises, calf pumps, and heel slides.The goal during this phase is to protectthe graft while regaining quadricepsstrength and full passive and active kneeextension symmetrical to the uninvolvedside. At the rst postoperative visit (1

week), we init iate heel-to-toe gait train-ing with the brace unlocked and enrollthe patient in formal physical therapy.Important milestones for ROM are fullpassive extension within 1 week and fullactive extension within 2 weeks. Goalsfor knee exion are 90 by 2 weeks andfull symmetrical exion by 8 weeks afterreconstruction. The patient is allowed to

wean himself or herself from crutchesafter 6 weeks.

As rehabilitation progresses, sport-specic activities are initiated. Thereshould be a logical, supervised progres-sion from protected, simple exercises tocomplex, sport-specic drills aimed atregaining neuromuscular control andreturning the patient to full participa-tion. Some protocols follow a time linefor transition through specic phases,assuming that graft incorporation willoccur over time and that protecting the

FIGURE 9. The tibial guide pin placement is veriedvia uoroscopy on anteroposterior (A) and lateral

(B) views.

FIGURE 10. Arthroscopic view of graft passage before(A) and after (B) the bone plug has been advancedinto the femoral tunnel. Fluoroscopic imaging toconrm EndoButton placement (C).

FIGURE 11. Postoperative radiographs followingallograft anterior cruciate ligament reconstruction.


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[ CLINICAL COMMENTARY ]graft will allow for incorporation and pro-gression of activities once adequate timehas passed. Other protocols follow objec-tive measurements of muscle strength

in the involved and uninvolved sides.Once the patient has regained adequatestrength and proprioception to minimizethe forces transmitted across the graftand adequate healing/maturation hastaken place, the patient is allowed to re-turn to sport.

A combination of the previous ap-proaches is used to best rehabilitate pa-tients; however, good measures of patientrehabilitation and adequate assessmentprior to return to sport are lacking in

the literature.6

Suggested objective mea-sures to determine a patients readinessto return to sport include muscle strengthtesting, thigh circumference, ROM, laxitytesting, validated questionnaires, and hoptesting. 6,57 Specically, the importance oftesting the involved extremity in isola-tion (eg, unilateral hop tests) is increas-ing because unilateral decits may not beapparent during bipedal tasks. 11,36 Devel-oping and adhering to these protocols iseven more important for individuals with

an allograft. Compared to autografts, al-lografts are at greater risk of rupture, andthey undergo delayed incorporation andhealing. Additionally, with allografts, pa-tients experience less morbidity associ-ated with graft harvesting, particularly inthe early phases of rehabilitation, whichfurther increases the risks of being overlyaggressive during rehabilitation. Progres-sion through the rehabilitation process isindividualized, based on an evaluation ofobjective measures during each phase of

rehabilitation. Guidelines can be helpfulto allow for adequate graft incorporationand healing ( APPENDIX).

Return to PlayThe expected return to full activity istypically 9 to 12 months after surgery(APPENDIX). However, accelerated rehabil-itation programs that allow early returnto sport have been described. 14 Theseprograms have drawn the attention ofathletes and coaches who have new ex-

pectations and pressures for surgeons tomeet those expectations. These protocolsshould be utilized with caution. Biologichealing and incorporation of ACL grafts

require time. 12 Rehabilitation protocolshave not been shown to change the timeto graft healing and maturation. Mount-ing data have shown that the reconstruct-ed ACL is at greatest risk of failure duringthe initial 9 months following reconstruc-tion, especially in patients undergoing al-lograft reconstruction. 56

More systematic protocols examiningobjective measures for return to sport are being developed. The specic measuresproposed include the visual analog scale

for pain, thigh circumference, ROM,the International Knee DocumentationCommittee Subjective Knee Form, hoptests, and isokinetic testing. 57 Other po-tential measures include an assessmentcomparing the involved and contralateralsides, fatigue resistance, and measuresof neuromuscular control. By develop-ing these measures, we may be able to better assess the protective capabilitiesof dynamic knee stabilizers prior to re-turn to play. These tests are even more

important for patients with an allograft-reconstructed knee, where healing andcellular repopulation are delayed. 12 Asstated earlier, the risks associated withan accelerated program in this popula-tion are compounded by the fact thatthese patients clinically appear ready toprogress more rapidly than patients whohave the morbidity associated with auto-graft harvesting.

Bracing and ACL-R

Perceived benets of bracing following ACL-R are decreased swelling, improvedROM, protection of the graft, improvedproprioception, and improved walkingkinematics to regain a normal gait pat-tern. 8 Knee immobilizers, functional braces, and hyperextension bracing haveall been described as options in the im-mediate postoperative period. 34 The ben-et of bracing in the early postoperativeperiod has been demonstrated primarilyfor swelling and ROM, because bracing

does appear to help achieve full kneeextension. 33,34

The use of functional bracing follow-ing ACL-R has not had a clear role in the

late phases of rehabilitation. Routine bracing to achieve satisfactory objectiveoutcome measures of stability, strength,single-leg hop performance, and ROMhas been under scrutiny, as the literaturehas not demonstrated that braces are ef-fective at achieving those goals. 32,59 How-ever, functional bracing appears to helpprevent reinjury in skiers. 53

Effect of Allograft Tissue on RehabilitationThe use of allograft tissue allows for reha-

bilitation without the postoperative morbidity of autograft harvesting. Allograftsare associated with less anterior kneepain and hamstring weakness than pa-tellar tendon and hamstring autografts,respectively. 23,54 As a result, patients withallograft ACL-R may be better preparedfor early physical therapy, which may al-low for easier progression of and adher-ence to exercises than for those who haveundergone autograft ACL-R. Even so, al-lograft ACL-R should follow a delayed re-

habilitation protocol to allow for allograftincorporation and healing, as discussedearlier. 12

It has been demonstrated that thestrength of nonirradiated allograft tissueis comparable to that of autograft tissue.However, allograft remodeling (ligamen-tization) and incorporation are slowerand presumably more susceptible to earlyfailure. 7,17 This hypothesis was tested viaa model that compared patellar-tendonautografts to allografts in goats that un-

derwent ACL-R. The authors showedthat after 6 months, the autograft-recon-structed knees had less anterior/poste-rior displacement, twice the force to ACLfailure, a greater cross-sectional area, anda greater number of small-diameter col-lagen brils. 21 In our practice, we delaythe return-to-play time line for patients who undergo allograft ACL-R (6 to 9months for autograft ACL-R and 9 to 12months for allograft reconstruction). Inthis study, compared to autograft tissue,


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allograft tissue demonstrated more simi-lar cellular repopulation and reorganiza-tion of collagen brils to the native ACL,albeit at a delayed rate. 21 Greater laxity at

6 months in the allograft group, as mea-sured by anterior translation, was notedas well, leading the authors to suggestprolonged protection in patients under-going allograft ACL-R. 21

GRAFT PROCESSING

To minimize the risk of diseasetransmission from the allograft,careful processing of the tissue is

paramount. Contamination can occur

from pathogens originating within thedonors blood/organs or during tissueprocessing/packaging. This process be-gins with a careful screening of all donorsfor risk factors of communicable disease.To minimize the risk of harvesting a con-taminated graft, standards for the timingand methods of procurement have beenset by the American Association of Tis-sue Banks.

Terminal sterilization is the last step before the graft can be stored and even-

tually utilized for ACL-R. Historically,ethylene oxide and gamma irradiationhave been effective in terminal steriliza-tion; however, ethylene oxide has beenshown to result in chronic synovitis andhas largely been abandoned in favor ofgamma irradiation. 22 Relatively low doses(1.5-2.0 mrad) can effectively kill bacte-ria, fungi, and spores. To deactivate HIV,doses of 2.5 mrad are required. 16,49 A bio-mechanical trade-off exists at doses above2.0 mrad: studies have demonstrated a

reduction in the biomechanical proper-ties of the graft. 13,15 Newer methods ofsterilization have been developed andpatented by various companies. Thesemethods include patented washes thatuse a combination of detergents, antibi-otics, alcohol, and peroxide to safely dis-infect the tissue and minimize the risk ofdisease transmission while limiting thedetrimental effect on the biomechanicalproperties of the graft. As these newermethods are rened, future studies will

be needed to dene their effects on the biomechanical properties of the graft.

OUTCOMES

Allografts

Allograft options includegrafts with bone-to-bone healing(patellar tendon, quadriceps ten-

don, Achilles tendon) and those withsoft tissue alone (hamstring, anteriortibialis, posterior tibialis, and peroneuslongus tendons). In the long term, al-lograft tissue has been shown to undergoligamentization and resemble the native ACL both grossly and microscopically. 21,37

Clinically, the reported failure rates of al-lograft tissue vary. When looking at tibi-alis anterior allografts, the literature isinconsistent, with good outcomes andlow failure rates (5.5%) reported in somestudies 50 and early graft slippage andfailure rates as high as 23% in youngpatients in other studies. 47,48 Interest-ingly, the age-dependent variation inoutcomes has not been established in bone-patellar tendon-bone allografts.Barber et al 5 showed no difference in

outcomes between patients older than40 years and patients younger than 40 years when bone-patellar tendon-boneallografts were used. One theory is thatthe variation in healing between youngerand older patients may be negated by theprocess of bone-to-bone healing in bone-patellar tendon-bone allografts.Comparison to Autografts Historically,outcome research has reported compa-rable results between allograft and au-tograft ACL-R. Initial outcome studies

found similar stability between groups, with less morbidity for the allograftgroup. 2,19 Some outcomes, such as post-operative ROM, appeared to favor al-lograft reconstruction. 19 These studies were generally smaller cohorts, and theresults were not always reproducible.

Recently, several meta-analyseshave reviewed the recent literature andcompared the outcomes of allograft re-construction to those of autograft recon-struction, with mixed results. Carey et

al10 reviewed laxity data in addition tosubjective outcomes after a minimumfollow-up of 2 years. This study evalu-ated 191 autograft and 266 allograft

reconstructions and found no signi-cant difference between groups. In thisreview, patients treated with bone plugand soft tissue reconstructions wereincluded in both groups. Rerupture ofthe reconstructed ACL was not speci-cally examined but was included withall other reasons for failure of the re-construction, with the data favoring theuse of autografts. A signicant rerupturerate was identied in the allograft groupin a meta-analysis by Krych et al 24 that

compared bone-patellar tendon-boneallografts to autografts. In that study,256 autograft reconstructions and 278allograft reconstructions were evaluatedafter a minimum follow-up of 2 years.Return to sport was allowed between6 and 12 months after reconstruction.Results on the Lachman and pivot shifttests and rates of return to the preinjurylevel of activity were similar betweengroups.

In one of the largest meta-analyses,

Prodromos et al40

compared the stabilityof allograft and autograft reconstructionsafter a minimum of 2 years of follow-up.The authors found that the use of auto-grafts resulted in signicantly better kneestability compared to allografts. Theythen compared soft tissue allografts tosoft tissue autografts and bone-tendonallografts to bone-patellar tendon-boneautografts. The nding of improved stability with autograft reconstruction wasstill present when soft tissue grafts were

used. A similar but less pronounced trend was present in the bone-tendon recon-structions. In summary, short-term datahave demonstrated subtle differences instability and graft rerupture rates be-tween allograft and autograft ACL-R.

Longer follow-up has helped to dem-onstrate differences in graft choices between populations. Spindler et al 51 re-ported on a cohort of 446 patients, 84%of whom were still being followed after 6 years. Their ndings suggest greater im-


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REFERENCES

1. Allen CR, Giffin JR, Harner CD. Revision anteriorcruciate ligament reconstruction.Orthop ClinNorth Am. 2003;34:79-98.

2. Bach BR, Jr., Aadalen KJ, Dennis MG, et al.Primary anterior cruciate ligament reconstruc-tion using fresh-frozen, nonirradiated patellartendon allograft: minimum 2-year follow-up. AmJ Sports Med. 2005;33:284-292.

3. Bach BR, Jr., Jones GT, Sweet FA, Hager CA.Arthroscopy-assisted anterior cruciate ligamentreconstruction using patellar tendon substitu-

tion. Two- to four-year follow-up results. Am JSports Med. 1994;22:758-767.

4. Baer GS, Harner CD. Clinical outcomes of al-lograft versus autograft in anterior cruciateligament reconstruction.Clin Sports Med.2007;26:661-681.http://dx.doi.org/10.1016/j.csm.2007.06.010

5. Barber FA, Aziz-Jacobo J, Oro FB. Anteriorcruciate ligament reconstruction using patellartendon allograft: an age-dependent outcomeevaluation. Arthroscopy. 2010;26:488-493.http://dx.doi.org/10.1016/j.arthro.2009.08.022

6. Barber-Westin SD, Noyes FR. Factors used to de-termine return to unrestricted sports activitiesafter anterior cruciate ligament reconstruction.

Arthroscopy. 2011;27:1697-1705.http://dx.doi.org/10.1016/j.arthro.2011.09.009

7. Barbour SA, King W. The safe and effective useof allograft tissue--an update. Am J Sports Med.2003;31:791-797.

8. Beynnon BD, Johnson RJ, Fleming BC, et al.The effect of functional knee bracing on theanterior cruciate ligament in the weightbearingand nonweightbearing knee. Am J Sports Med.1997;25:353-359.

9. Bottoni CR, Liddell TR, Trainor TJ, FrecceroDM, Lindell KK. Postoperative range of mo-tion following anterior cruciate ligamentreconstruction using autograft hamstrings:

a prospective, randomized clinical trial ofearly versus delayed reconstructions. Am JSports Med. 2008;36:656-662. http://dx.doi.org/10.1177/0363546507312164

10. Carey JL, Dunn WR, Dahm DL, Zeger SL,

Spindler KP. A systematic review of anteriorcruciate ligament reconstruction with autograftcompared with allograft.J Bone Joint Surg Am.2009;91:2242-2250. http://dx.doi.org/10.2106/JBJS.I.00610

11. Chmielewski TL. Asymmetrical lower extremityloading after ACL reconstruction: more thanmeets the eye. J Orthop Sports Phys Ther .2011;41:374-376.http://dx.doi.org/10.2519/jospt.2011.0104

12. Corsetti JR, Jackson DW. Failure of anterior cru-ciate ligament reconstruction: the biologic basis.Clin Orthop Relat Res. 1996;325:42-49.

13. Curran AR, Adams DJ, Gill JL, Steiner ME,Scheller AD. The biomechanical effects of low-dose irradiation on bone-patellar tendon-boneallografts. Am J Sports Med. 2004;32:1131-1135.http://dx.doi.org/10.1177/0363546503260060

14. Decarlo MS, Shelbourne KD, McCarroll JR, RettigAC. Traditional versus accelerated rehabilitationfollowing ACL reconstruction: a one-year follow-up. J Orthop Sports Phys Ther . 1992;15:309-316.

15. Fideler BM, Vangsness CT, Jr., Lu B, OrlandoC, Moore T. Gamma irradiation: effects on bio-mechanical properties of human bone-patellartendon-bone allografts. Am J Sports Med.1995;23:643-646.

16. Fideler BM, Vangsness CT, Jr., Moore T, Li Z,Rasheed S. Effects of gamma irradiation on thehuman immunodeciency virus. A study in fro-zen human bone-patellar l igament-bone graftsobtained from infected cadavera. J Bone JointSurg Am. 1994;76:1032-1035.

17. Gulotta LV, Rodeo SA. Biology of autograftand allograft healing in anterior cruciateligament reconstruction. Clin Sports Med.2007;26:509-524. http://dx.doi.org/10.1016/j.csm.2007.06.007

18. Harner CD, Irrgang JJ, Paul J, Dearwater S,Fu FH. Loss of motion af ter anterior cruciateligament reconstruction. Am J Sports Med.1992;20:499-506.

19. Harner CD, Olson E, Irrgang JJ, Silverstein S,Fu FH, Silbey M. Allograft versus autograftanterior cruciate ligament reconstruction:3- to 5-year outcome. Clin Orthop Relat Res.

1996;324:134-144. 20. Hunter RE, Mastrangelo J, Freeman JR, Purnell

ML, Jones RH. The impact of surgical timingon postoperative motion and stability followinganterior cruciate ligament reconstruction. Ar-throscopy. 1996;12:667-674.

21. Jackson DW, Grood ES, Goldstein JD, et al. Acomparison of patellar tendon autograft andallograft used for anterior cruciate ligamentreconstruction in the goat model. Am J SportsMed. 1993;21:176-185.

22. Jackson DW, Windler GE, Simon TM. Intraarticu-lar reaction associated with the use of freeze-dried, ethylene oxide-sterilized bone-patella

provements in validated knee scores andreturn-to-sport function in patients whounderwent autograft reconstruction. Inaddition, a recent study on a cohort of

military cadets demonstrated the ACLrerupture rate to be as much as 3 timeshigher after allograft reconstructionthan after autograft reconstruction. 39 Asa result, there has been a trend towardfavoring autograft reconstruction inhigher-demand, younger athletes.

COMPLICATIONS

Complications specic to the me-dial portal technique for ACL-R can

occur secondary to incorrect place-ment of the medial portal and resultantdamage to the medial femoral condyle.This is usually the result of inadequateclearance from the medial femoral con-dyle for safe passage of the guide pins anddrill bits. Other complications generallyassociated with arthroscopic ACL-R us-ing either autograft or allograft tissueinclude iatrogenic injury to the menisci,articular cartilage, and tibial spines,postoperative infection, arthrofibro-

sis, deep vein thrombosis, or failure ofgraft healing despite a properly executedreconstruction.

Complications related specically toallograft tissue primarily relate to therisk of disease transmission and the im-mune response to allograft tissue by thehost. The potential for infection is low, with few reported cases in the literatureof either viral (HIV and hepatitis) or bac-terial transmission. 55 The HIV transmis-sion rate is approximately 1 in 1.5 million.

The risk of disease transmission can bereduced by polymerase chain reactiontesting for viral transmission and closeadherence to the recommendations forscreening, harvesting, and storage out-lined by the American Association ofTissue Banks. Complications associated with autograft harvesting, which can beavoided by utilizing allograft tissue, in-clude fracture of the donor site that canresult from quadriceps and bone-patellartendon-bone harvesting.

SUMMARY

When deciding between al-lograft and autograft ACL-R,

it is important to consider theadvantages and disadvantages of eachtechnique and which graft option will

best address the patients needs. Theseconsiderations will extend into the post-operative period. Extra caution is neces-sary when allograft tissue has been usedfor ACL-R, because patients tend to clini-cally improve faster than their graft canincorporate itself. As a result, they maydesire a return to activities that the graftis not yet prepared to handle.
http://dx.doi.org/10.1016/j.csm.2007.06.010http://dx.doi.org/10.1016/j.csm.2007.06.010http://dx.doi.org/10.1016/j.arthro.2009.08.022http://dx.doi.org/10.1016/j.arthro.2011.09.009http://dx.doi.org/10.1016/j.arthro.2011.09.009http://dx.doi.org/10.1177/0363546507312164http://dx.doi.org/10.1177/0363546507312164http://dx.doi.org/10.2106/JBJS.I.00610http://dx.doi.org/10.2106/JBJS.I.00610http://dx.doi.org/10.2519/jospt.2011.0104http://dx.doi.org/10.2519/jospt.2011.0104http://dx.doi.org/10.1177/0363546503260060http://dx.doi.org/10.1016/j.csm.2007.06.007http://dx.doi.org/10.1016/j.csm.2007.06.007http://dx.doi.org/10.1016/j.csm.2007.06.007http://dx.doi.org/10.1016/j.csm.2007.06.007http://dx.doi.org/10.1177/0363546503260060http://dx.doi.org/10.2519/jospt.2011.0104http://dx.doi.org/10.2519/jospt.2011.0104http://dx.doi.org/10.2106/JBJS.I.00610http://dx.doi.org/10.2106/JBJS.I.00610http://dx.doi.org/10.1177/0363546507312164http://dx.doi.org/10.1177/0363546507312164http://dx.doi.org/10.1016/j.arthro.2011.09.009http://dx.doi.org/10.1016/j.arthro.2011.09.009http://dx.doi.org/10.1016/j.arthro.2009.08.022http://dx.doi.org/10.1016/j.csm.2007.06.010http://dx.doi.org/10.1016/j.csm.2007.06.010


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Phase 1: 0 to 6 Weeks

Goals Protect graft xation Minimize effects of immobilization Control inammation Full extension range of motion Educate patient on rehabilitationBrace: 0 to 1 week, locked in full extension for ambulation and sleeping 1 to 6 weeks, unlocked for ambulation, remove for sleepingWeight-bearing status:

0 to 6 weeks, weight bearing as tolerated with 2 crutchesTherapeutic exercises: Heel slides Quadriceps sets, hamstring sets Patellar mobilization Nonweight-bearing gastrocnemius/soleus, hamstring stretches Straight leg raise (all planes) with brace locked in full extension until

quadriceps strength is sufficient to prevent extension lag Quadriceps isometrics at 60 and 90 of knee exion

Phase 2: 6 to 8 Weeks

Criteria for Advancement to Phase 21. Good quadriceps set, straight leg raise without knee extension lag

2. Approximately 90 of knee exion3. Full extension4. No signs of active inammationGoals Initiate weight-bearing (closed kinetic chain) exercises Restore normal gait Protect graft xationBrace/weight-bearing status: Discontinue use of brace and crutches as allowed by physician when

the patient has full extension and can perform a straight leg raise with-out extension lag

Patient must exhibit nonantalgic gait pattern. Consider using singlecrutch or cane until gait is normalized

Therapeutic exercises: Wall slides, 0 to 45, progressing to minisquats 4-way hip Stationary bike (begin with high seat and low tension to promote range

of motion. Progress to single leg) Weight-bearing terminal knee extension with resistive tubing or weight

machine Toe raises Balance exercises (eg, single-leg balance) Hamstring curls Aquatic therapy with emphasis on normalization of gait

Continue hamstring stretches. Progress to weight-bearinggastrocnemius/soleus stretches

Phase 3: 2 to 6 Months

Begins at approximately 8 weeks and extends through approximately6 months

Goals Full range of motion Improve strength, endurance, and proprioception of the lower extremity

to prepare for functional activities Avoid overstressing the graft

Protect the patellofemoral jointTherapeutic exercises: Continue and progress previous exibility and strengthening activities Seated knee extensions, 90 to 45, and progress to eccentrics Advance weight-bearing activities (leg press, single-leg minisquats

0 to 45 of exion, step-ups beginning at 5 cm and progressingto 20 cm, etc)

Progress proprioceptive activities (slide board, use of ball, etc) Progress aquatic program to include pool running, swimming

Phase 4: 6 to 9 Months

Begins at approximately 6 months and extends through approximately9 months

Criteria for Advancement to Phase 41. Full, pain-free range of motion2. No evidence of patellofemoral joint irritation3. Strength and proprioception of approximately 70% of the uninvolved

side4. Physician clearance to initiate advanced weight-bearing exercises and

functional progressionGoals Continue and progress previous exibility and strengthening activities Functional progression, including:

- Walk/job progression- Forward/backward running at half, three-quarters, and full speed

Phase 5: After 9 MonthsCriteria for Advancement to Phase 51. No patellofemoral or soft tissue complaint2. Necessary joint range of motion, strength, endurance, and propriocep-

tion to safely return to work or athletics3. Physician clearance to resume partial or full activityGoals Initiate cutting and jumping activities Completion of appropriate functional progression Maintenance of strength, endurance, and proprioception Patient education with regard to any possible limitations

APPENDIX

REHABILITATION FOLLOWING ALLOGRAFT ACL RECONSTRUCTION


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jo rnal of orthopaedic & sports ph sical therap | ol me 42 | n mber 3 | march 2012 | 207

Therapeutic exercises:

Functional progression, including but not limited to the following:- Walk/job progression- Forward/backward running at half, three-quarters,

and full speed- Cutting- Plyometric activities appropriate to patients goals

- Sport-specic drills

Safe, gradual return to sport after successful completion of functionalprogression

Maintenance program for strength and enduranceBrace: Functional brace may be recommended by the physician for use during

sports for the rst 1 to 2 years after surgery

APPENDIX

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Allograft Acl 2012