Introduction

About 100.000 anterior cruciate liga-ment (ACL) reconstructions are performedcurrently in Europe per year. Inspite of thesignificant improvements of the intraarticu-lar techniques, there is an obvious increasein the number of failures following thesereconstructive proceduresdur to the increas-

ing numbers of primary reconstructiones.Revision ACL surgery is technically de-manding and requires a great deal of perso-nal theoretical and clinical experience. Ca-reful preoperative planning is vital. Techni-cal considerations include skin incisions,tunnel size and placement, identification ofexact hardware types and location, and an

48 • Wiosna 2002

New techniques for anteriorcruciate ligament revision surgery

H.H. Paessler, D.S. Mastrokalos, E.K. Motsis

Center for Knee and Foot Surgery,Sports Trauma, ATOS-Clinic,

Heidelberg

SummarySimiliar to the development in joint replacementsurgery, revision surgery is becoming more and mo-re important in Anterior Cruciate Ligament (ACL)surgery. Localisation and volume of previous tun-nels are crucial for planning revision surgery. Basedon these different tunnel conditiones, a new gradingsystem has been developed indicating the difficultyof the upcoming revision surgery. Evaluation of ourmore than 500 cases of ACL revision surgery dem-onstrated in 74% malposition of the previous bonetunnels as the reason for graft failure and revision.Severely abnormal tunnel position allows in gener-ally for new tunnel drilling in the correct position(Grade 1 revision). Isolated tibial tunnel dilation isseen mainly following ACL reconstruction usingbone-patellar tendon-bone grafts (BPTB). In mostof these cases the femoral tunnelI is obliterated bythe bone block of the BPTB (Grade II). In these ca-ses, bone grafting of the tibial tunnel alone is fre-quently neccessary. Severe dilation of both the tibialand femoral tunnels are seen mainly following ACLreconstruction using hamstrings with graft fixationfar away from the anatomical side (Grade III). Inthese cases bone grafting of the both old and drillingof new tunnels in the correct position as a one stageprocedure might be a possible solution. On the tib-ial side the tunnels may be positioned or dilated toofar anteriorly and/or posteriorly or medially. In so-me instances the opening of the old tunnel by osteo-tomy may be the safest approach for revision, espe-cially if the old graft is still functioning but loose.

A new technique for harvesting bone grafts from theiliac crest using specially designed bone cutting tu-bes was developed. 20 – 70 mm long and 8 – 15 mmlarge cortico-cancellous grafts may be cut out of thecrest using a single 2 – 3 cm incision. The previousenlarged tunnels are reamed up in order to excisethe sclerotic wall and achieve a cylindric form. Aniliac crest graft with a diameter 1 mm more than thetunnel will be inserted press-fit. Then the new tun-nel is drilled at its correct position. This allows sing-le stage procedure in many of the grade III revisioncases. Rehabilitation depends on the revision grade.Grade 1 revisions are treated postoperatively likeprimary ACL reconstructions. Grade II and III revi-sions using more or less amounts of bone graftinghave to be rehabilited delayed with partial weightbearing for about 6 weeks. Results: Between 1/93and 12/95 108 failed ACL reconstructions under-went revision surgery, all performed by one surgeon(HHP). During the same time 288 ACL ruptureshave been reconstructed in this center (HHP). 16patients (15%) were lost for follow up. The remain-ing 92 patients were 32 women, 64 men. The agerange was 28 years (17 – 44). The overall IKDC rat-ing at 3.3 (2 – 6) years followup demonstrates, thatearly revision has better results than late ones (p.01).But the best results still are obtained with primaryreconstruction using correct tunnel positions (p.01).[Acta Clinica 2002 2:48-60]

Key words: ACL reconstruction, ACL revision sur-gery, tunnel dilation, bone grafting, grading system

analysis of notch size and notch impinge-ment. In cases of large, capacious tunnels,cystic changes, or osteolysis, often seconda-ry to the use of prosthetic ligaments, stag-ing of the reconstruction might be favour-able. In cases of significant varus thrust andadditional lateral or posterolateral instabili-ty, osteotomy must be considered either incombination with the ACL reconstructionor as a two stage procedure. The pa-tient’s co-operation and motivation are cru-cial. Already disappointed because of failedprimary ACL surgery, mental preparationof the patient is imperative. The patientshould understand his problem and knowthe potential outcome without having falseexpectations, and must maintain a positivemental outlook.

Causes of failure

Graft failures may result from a num-ber of factors acting either alone or in com-bination (Table 1) (5) and are mostly ca-used by problems involving the surgicaltechnique (1,8). The most frequent causefor failure in a study of 350 revisions follo-wing ACL reconstruction and all operatedfrom the senior author (H.H.P.) was in74% improper tunnel placement with orwithout impingement (Figure 1). AlsoWetzler et al. (1998) (7) estimated the inci-dence of malposition to be between 70 and80%. Due to better understanding, and the

use of drill guides, tunnels are in a moreacceptable, but often still not ideal position.Therefore the new tunnel will involve partsof the previous one, which results in a verylarge tunnel. In addition, with distant graftfixation techniques, such as Endobut-ton-tape fixation, tunnel dilation is also se-en more frequent (Bungee and windshieldwiper effect) (2). In order to avoid stagedsurgery, new techniques for primary stablegrafting of the enlarged tunnels allowingimmediate reconstruction had been devel-oped.

Indications

Indications for revision ACL-recon-struction are:

1. subjective feeling of instability duringthe normal daily and sports activities.

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New techniques

Preoperative Intraoperative Postoperative

State of secondary constraints Inadequate notchplasty Improper graft incorporation

State of menisci Improper tunnel placement Improper rhabilitation

State of cartilage Improper tensioning Trauma

Inadequate fixation

Faulty selection/harvest of graft

Table 1. Factors causing graft failure (Vergis et al 1995) (2)

Fig. 1. Reasons for failure in 350 ACL reconstruc-tions

2. functional instability with or withoutpain under weight bearing.

3. Objective anterior laxity (during theclinical examination) with positive Lach-man test and significant KT-1000 si-de-to-side difference.

New grading system of ACL

revision surgery

For the planning of a revision case con-cerning the difficulty of surgery and even-tually staging it seemed to be appropriate todevelop a classification system based onprevious tunnel positions, tunnel enlarge-ment, cartilage and meniscal conditions,and eventual deficiant secondary restraints.Grade I indicates a simple revision similiarto primary reconstruction, whereas GradeIV (Table 1). is the most difficult one, in-volving multiple surgical steps (bone graft-ing, osteotomy, peripheral ligament recon-struction, meniscal allograft etc.) (figs. 8a,10a, 26a, 33).

Graft selection

In Europe, autografts generally areused in primary ACL surgery as well as inrevision surgery. Synthetic grafts, originallyused in these so-called salvage procedures,have been abondend. Allografts are rarelyavailable in Europe. Allografts are used on-ly in cases of bilateral multidirectional revi-sion instabilities (6).

For autograft tissue there are multiplesources. These include patellar tendons,hamstrings or quadriceps tendons, from ei-ther the injured or non-injured leg. Theo-retically this allows up to six revisions forone knee or 3 revisions if both knees are in-volved. The main advantage of the patellartendon is the possibility of harvesting itwith a large bone block from the tibial at-tachment in order to fill up spacious bonetunnels.

If for the previous reconstructiona BPTB graft was used, in most cases thebone block or the graft was fixed in the fe-mur close to the notch wall using an interfe-rence screw. After removal of the screw,a new tunnel posterior to the interferencesrew may be drilled leaving a sufficiant largeand stable bone bridge between the screwdefect and the new tunnel. A semitendino-sus and gracilis tendon is our first choice forthis second reconstruction. The second cho-ice would be a quadriceps tendon graft. Ifhamstrings were used as a graft at the pri-mary reconstruction, a BPT graft or a quad-riceps graft from the same knee could beharvested. If these graft sources are not ava-ilable in the injured knee due to the use forprevious reconstructions, a graft would beharvested from the controlateral knee.

Hardware removal

Hardware removal may be the mostchallenging part of the procedure. Radio-graphic evaluation is vital to determine di-rection and position of screws, staples orwires. Such information is necessary to de-termine whether hardware might compro-mise the drilling of a new tunnel or whe-ther it can be left in place. In ACL revisionsurgery, the availability of a collection ofspecial instruments for hardware extractionis imperative. They should include all sizesof screwdrivers and multiple sizes of coringreamers. Furthermore, a counterclockwisereversed thread for removing stripped inter-ference screws can be used. The alternativefor broken AO screws is a reversed threa-ded internal drill bit, both with clockwiseand counter clockwise thread, dependingon from which end the screw must be re-moved. Also a bone harvesting tube, mat-ching the size of the screw, may be insertedunder fluoroscopic control over the screwfor retraction (Fig. 2) Staples can be remo-ved most easily by using an elevator rather

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than an extractoror osteotome.Small chisels andgouges can behelpful for remo-ving any bone,covering thescrews. In caseswhere removinghardware might

result in excessive loss of bone, necessitat-ing bone grafting or staging of the procedu-re, it is better to leave it in place and chan-ge the tunnel direction (4). Removal of pro-sthetic ligament devices can present prob-lems. All intraarticular synthetic materialshould be completely removed (4). Often,in cases of severe abrasion synovitis, thishas to be combined with synovectomy.

Revision notchplasty

Notchplasty in revision cases eliminatesimpingement and facilitates correct femoraltunnel placement. This should also includeremoval of posterior osteophytes.

Bone grafting for enlarged tunnels

All Grade II-IV revisiones demands ingenerally for bone grafting. A new atrau-matic harvesting technique for cylindric bo-ne blocks has been developed: The iliaccrest is exposed using a 2 cm incision. TwoK-wires mark the internal and externalwall of the iliac crest (Figures 3, 4). A 6 to8 cm long cortico-cancellous bone graft isharvested using specially designed bonecutting tubes with an external diameterranging from 12 to 16 mm (Figures 5, 6).Due to the V-form of the ileum, the plug iswedge-shaped at its distal end. The harves-ted bone is divided into one cylindrical andone wedge-shaped plug (Figure 7).

Bone tunnel revision and placement

of new graft

Grade I:

a) Narrow femoral tunnel and tibial

tunnel in correct position

b) Femoral ± tibial tunnel far away

from correct position

The previous tunnel is located in quad-rant 1 or 2 on both the femoral and tibialside according to the classification of Har-

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New techniques

Fig. 3+4. Iliac crest with 2 mm incision. K-wiresmarks direction of bone wall

Fig. 2. Hardware removal

ner (1). In these cases new tunnels have tobe drilled in the correct position. Hardwaremay be disregarded or removed if compli-cating the new tunnels’ drilling. If the fem-oral tunnel is just slightly more anterior,the tunnel can be expanded posteriorly and

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Fig. 5+6. Harvested cortico-cancellous bone graftwith spezial bone cutting tubes

Fig. 8 a. Grade I. Small femoral tunnel and tibialtunnel in correct position

Fig. 8 b. Both tunnels too far anterior

again, the new tunnel can be drilled diver-gent to the old tunnel (Fig. 9). If this is notpossible, a graft bone plug can be used. Be-cause of drilling the femoral tunnel withthe knee flexed to 120, all to 130 degrees,the tunnels are directed perpendicular toBlumensaat’s line. Since most of the tun-nels in revision cases had been positionedin a more oblique direction (flat angle toBlumensaat’s line), it is easy to avoid theold tunnel even in cases of less anterior po-sition.

Grade II:

Large tibial tunnel + small femoral

tunnel or previous tunnel closed by bone

block of initial graft (Fig. 10a, 10b)In such a case drilling of a new femoral

tunnel is easy, leaving a bone bridge betwe-en the previous and the new tunnel. Thedilated tibial tunnel is bone grafted anda new tunnel is driled in a correct positionunder fluoroscopic control in a one stageoperation.

Two different technical steps allow therevision of the tibial tunnel: a) opening of

the previous tunnel by osteotomy and b)tunnel expansion with resection of the scle-rotic wall.

a) opening of the previous tunnel by

osteotomy

A K-wire is positioned into the old tun-nel manually. If the tibial entrance is oblit-erated, a drill guide is used for the placem-net of the K-wire. Using an oscillating saw,

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New techniques

Fig. 9. Semitendinosus/gracilis graft in completelynew tunnels

Fig. 10 b. Large, capacious tibial tunnel (postop.Hamstring graft)

Fig. 10 a. Grade II. Large tibial tunnel + smallfemoral tunnel or previous tunnel closed by boneblock or initial graft

two parallel cuts are performed in directionof the K-wire medially and laterally to it ina distance of about 8 – 10 mm. The result-ing triangular bone chip is removed usinga small osteotom (Figs. 11, 12).

The opened tunnel can now be debri-ded easily including removal of the oldgraft (Figs. 13, 14). If the tunnel is slightlyanteriorly located, the tunnel can be expan-ded posteriorly and filled up anteriorly witha bone graft. If the previous tunnel is loca-

ted too far posteriorly, a posterior bonegrafting is necessary.

The new ACL graft is inserted into thenew femroal tunnel and than into the ope-ned tibial tunnel. The graft itself is fixed bytying the holding sutures over a distal bo-ne-bridge (see paragraph graft fixation). Fi-nally, the triangular bone chip is replacedinto the osteotomy and fixed with a staple(Figs. 14, 15). In most cases, this fixation issufficient and an additional interferencescrew is not necessary.

Alternatively, a resorbable interferencescrew fixation for both the graft and the bo-ne plug is possible. The CT-scan confirmsthe correct position of the graft (Figs. 17,18).

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Fig. 11. Placement of a 2.5 mm drill along the ante-rior border of the previous tunnel

Fig. 12. Opening the tunnel by removal of a 8 – 10mm bone chip

Fig. 13. Old hamstring graft in situ

Fig. 14. Debrided tunnel

b) tunnel expansion with resection of

sclerotic wall and bone grafting.

A K-wire is positioned into the old tun-nel manually. If the tibial entrance is oblit-erated, a drill guide is used for the placem-net of the K-wire.

The distal entrance of the tibial tunnelis overdrilled, the old graft is removed (Fig.19) and the previous tibial tunnel is debri-ded. The K-wire is drilled slightly into thenotch wroof in order tostabilize it into

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New techniques

Fig. 15. Replacement of bone chip

Fig. 16. Axial drawing of reconstruction. From po-sterior to anterior bone graft; tendon graft and bonechip with staple

Fig. 17. Axial CT-scan

Fig. 18. Sagittal CT-scan

Fig. 19. Graft removed from tunnel

a central positon in th tunnel. Than thetunnel is enlarged to a cylindric form byoverdrilling of the K-wire. By this meansthe sclerotic tunnel wall is also resected.A cylindric iliac crest bone is impacted intothe tibial tunnel preesfit (Figs. 20, 21).Now a new tibial tunnel is drilled underfluoroscopic controll in the correct position.If the previous tunnel was too far medialpositioned, involving the cartilage posteriorto the anterior horn of the medial menis-cus, the bone graft should be harvestedslighly oblique to the iliac crest in order tofit exactly to the surface of the tibial pla-

teau. In this case, the periosteum of thegraft should be preserved in order to enco-urage the repair with fiber cartilage.

Another cause of failure of an ACL re-construction may be the elongation of anintact and well positioned graft or initial fi-xation failure. This is seen mainly follow-ing reconstructiones in which soft tissuegrafts (hamstrings etc.) were used (Fig. 22).In these cases the tibial tunnel is opened byosteotomy as described above and the graft,including its osseus ingrowth zone, is mo-bilized (Figs. 23, 24). The graft is then refi-xed and the removed bone chip of the os-teotomy is repositioned and fixed it witha staple (Fig. 25).

Grade III:

Large femoral + tibial tunnel (Fig.26a)

In these revision cases, widening ofboth femoral and tibial tunnel occursmainly after ACL reconstruction usinghamstrings fixed far away from the anato-mical side (Fig. 26b). For the dilated tibialtunnel the technique described above forgrade II revision may be used. The dilatedfemoral tunnel has to be filled up usingiliac crest bone graft similiar to the techni-

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Fig. 20. Tunnel grafted with cylindric bone from il-liac crest

Fig. 21. Previous and new tunnel in CT-scanFig. 22. Loosening of tibial fixation with intacthamstring graft

que described above for closed tibial tunnelrevision. Then a new tunnel has to be dril-led in the correct position. The tunnelwidth is measured using impactors in halfmilimeters steps (Figure 27). A K-wire isinserted through the impactor and drilledinto the condyle. The K-wire is overdrilledusing a drill bit matching the width of the

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New techniques

Fig. 24. Mobilized graft with bone shell

Fig. 25. Graft refixed under tension

Fig. 23. Opening the tibial tunnel by osteotomy andmobilization of the graft

Fig. 26 b. Sagittal CT-scan: femoral and tibial tun-nel dilation after ACL reconstruction with quadrup-le hamstring graft

Fig. 26 a. Grade III. Large femoral + tibial tunnel(e.g.postop hamstrings)

tunnel entrance (Figure 27). The drill bitmay be changed against a bone cutting tu-be in order to gain cancellous bone forgrafting. Then a sufficiant long cylindriccortico-cancelous bone graft is harvestedaccording to the technique already descri-bed. The plug is introduced into the prepa-red femoral tunnel using one of the harves-ting tubes. If it does not fill out the oldtunnel entrance completely, a wedge-sha-ped plug is impacted additionally. Now thenew tunnel can be drilled in the correct po-sition (Figs. 29, 30). Using a bone-patellartendon graft (BPT) with a bone block onlyfrom the tuberositas, or a bone-quadricepstendon graft, the bone block is pulled into

the femoral tunnel using a holding sutureand impacted pressfit (Figs. 31, 32). Some-times, in cases of large, capacious tunnels,a staged procedure procedure may be nec-essary with primary bone grafting and ACLreconstruction 6 months later. In no casewe had to convert the procedure into an„over the top” two incision technique.

Grade IV:

Grade III and additional lesions of

secondary restraints osteoarthritis ± PCL(Fig. 33)

In these cases the new femoral and tib-ial tunnels are drilled as described in GradeII and III. In addition secondary restraintsare reconstructed by adequate graft techni-ques, the PCL is replaced or an osteotomyis performed at the same time, if possible.

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Fig. 27. Sizing of the tunnel using an impactor

Fig. 28. Tunnel expansion

Fig. 29. Femoral drill guide in correct position

Fig. 30. Redrill of tunnel

A meniscal allograft may be implanted si-multaneously or in staged procedure.

Graft fixation

For graft fixation a press fit techniqueon the femur is used, if possible. An addi-tional interference screw fixation is rarelynecessary. On the tibial side, a bone bridgeis created by drilling a 4.5 mm drillhole 10mm distal to the tibial tunnel outlet andcombining both drill holes using a curvedclamp. A Deschamp ligatur needle helps topass the holding sutures beneath the bonebridge. The holding sutures (Krackow su-tures, baseball sutures using Ethibond Nr2 or 3, Ethicon) of the graft are tied overthe bone bridge in full extension.

Rehabilitation

In revision cases of grade I, acceleratedrehabilitation can generally be used safely.In cases of additional extensive bone graft-ing or high tibial osteotomy (grades II toIV), partial weight bearing is necessary forat least 6 weeks. If secondary restraints arereconstructed, a brace is also mandatory.

Clinical experience and results

Between 1/1993 and 12/1995 108 failedACL reconstructions underwent revisionsurgery all performed by one surgeon(HHP). During the same time 288 ACLruptures have been reconstructed in thiscenter (HHP). 16 patients (15%) were lostfor followup. The remaining 92 patients in-cluded 32 women and 64 men. The agerange was 28 years (17 – 44). The overallIKDC rating at 3.3 (2 – 6) years follow-upis shown on table 3. It demonstrates thatearly revision has better results than lateones (p,01). But the best results still are ob-tained with primary reconstruction usingcorrect tunnel position (p,01). Conclusion

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New techniques

Fig. 31. Bone block of BPT graft is pulled into thefemoral tunnel and impacted pressfit

Fig. 32. Scetch of grafted and new tunnel

Fig. 33. Grade IV. Additional lesions of secondaryrestraints ±osteoarthritis ± PCL

Based on our 585 ACL revision cases bet-ween 1988 and 1999, we have found that itis possible to achieve acceptable to good re-sults by using the techniques just described.Early revision surgery has better resultsthan late revision due to secondary arthritis.

Preventing ACL reconstruction failureis imperative. This can be achieved by im-proved surgical techniques such as correcttunnel placement, use of adequate grafts,and metal free graft fixation. It is critical toaddress secondary restraints at the time ofthe initial surgery.

References:

1. Harner C.D., Marks P.H., Fu F.H., Irrgang J.J.,

Silby M.B., Mengato R.: Anterior Cruciate Liga-

ment Reconsruction: Endoscopic versus two-inci-

sion Technique. Arthroscopy (1994)10(5): 502 – 512.

2. Hher J., Mller H.D., Fu F.H.: Bone tunnel en-

largement after anterior cruciate ligament recon-

struction: fact or fiction? Knee Surg. Sports Trau-

matol. Arthrosc (1998) 6: 231 – 240.

3. Karts J., Stener S., Lindahl S., Eriksson B.I.,

Karlson J.: Ipsi- or Contralateral Patellar Tendon

Graft in Anterior Cruciate Ligament Revision Sur-

gery. A Comparison of two Methods. The American

Journal of Sports Medicine Vol. 26, No 4 (1998):

499 – 504.

4. Safran M.R., Harner C.D.: Technical considera-

tions of revision ACL surgery. Clin Orthop (1996)

325: 50 – 64.

5. Vergis A., Gillquist J.: Graft failure in Intra-Arti-

cular Anterior Cruciate Ligament Reconstructions:

A Review of the Literature. Arthroscopy Vol 11, No

3; 1995: 312 – 321.

6. Vorlat P., Verdonk R., Arnauw G.: Long-term re-

sults of tendon allografts for anterior cruciate liga-

ment replacement in revision surgery and in cases of

combined complex injuries. Knee Surg. Sports

Traumatol. Arthrosc (1999) 7: 318 – 322.

7. Wetzler M.J., Getelman M.H., Friedman M.J.,

Bartolozzi A.R.: Revision anterior cruciate ligament

surgery: Etiology of failures. Operative techniques

in Sports Medicine 6, 64 – 70 (1998).

8. Wirth C.J., Peters G.: The dilemma with multip-

ly reoperated knee stabilities. Knee Surg. Sports

Traumatol. Arthrosc. (1998) 6: 148 – 159.

Address fot correspondence: Dr med. Hans H. Pa-

essler ATOS-Clinic Heidelberg, Center for Knee

and Foot Surgery Bismarckstrasse 9 – 15 69115 Hei-

delberg — Germany Tel.: 0049 – 6221 – 983194 Fax.:

0049 – 6221 – 983199 e-Mail: paessler@atos.de

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60 • Wiosna 2002

IKDC rating Total revisions Early revisions Late revisions Primary

% % % reconstructions

A 10 17 3 25

B 44 57 40 57

C 31 21 39 17

D 15 5 18 1

Table 2. IKDC scoring system