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Tibial Rotation Under Combined In Vivo Loading After Single-and Double-Bundle Anterior Cruciate Ligament Reconstruction

Alexander Tsarouhas, M.D., Ph.D., Michael Iosifidis, M.D., Ph.D., Giannis Spyropoulos, M.Sc.,Dimitrios Kotzamitelos, M.D., Themistoklis Tsatalas, M.Sc., and Giannis Giakas, Ph.D.

Purpose: To evaluate in vivo the differences in tibial rotation between single- and double-bundleanterior cruciate ligament (ACL)–reconstructed knees under combined loading conditions. Methods:An 8-camera optoelectronic system and a force plate were used to collect kinematic and kinetic datafrom 14 patients with double-bundle ACL reconstruction, 14 patients with single-bundle reconstruc-tion, 12 ACL-deficient subjects, and 12 healthy control individuals while performing 2 tasks. The firstincluded walking, 60° pivoting, and stair ascending, and the second included stair descending, 60°pivoting, and walking. The 2 variables evaluated were the maximum range of internal-external tibialrotation and the maximum knee rotational moment. Results: Tibial rotation angles were notsignificantly different across the 4 groups (P � .331 and P � .851, respectively) or when side-to-sidedifferences were compared within groups (P � .216 and P � .371, respectively) for the ascendingand descending maneuvers, nor were rotational moments among the 4 groups (P � .418 and P �.290, respectively). Similarly, for the descending maneuver, the rotational moments were notsignificantly different between sides (P � .192). However, for the ascending maneuver, rotationalmoments of the affected sides were significantly lower by 20.5% and 18.7% compared with theirintact counterparts in the single-bundle (P � .015) and double-bundle (P � .05) groups, respectively.Conclusions: High-intensity activities combining stair ascending or descending with pivoting pro-duce similar tibial rotation in single- and double-bundle ACL-reconstructed patients. During suchmaneuvers, the reconstructed knee may be subjected to significantly lower rotational loads comparedwith the intact knee. Level of Evidence: Level III, retrospective comparative study.

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The restoration of the native anterior cruciate lig-ament (ACL) anatomy is considered the key el-

ment in achieving excellence in ACL reconstruction.natomic reconstruction of the ligament is defined as

ts functional restoration with respect to its native dimen-

From the Department of Physical Education and Sports Science,University of Thessaly (A.T., G.S., T.T., G.G.), Trikala; Orthopae-dic Department, Papageorgiou General Hospital (M.I.), Thessalo-niki; Orthopaedic Department, University Hospital of Alexan-droupolis (D.K.), Alexandroupolis; and Institute of HumanPerformance and Rehabilitation, Center for Research and Tech-nology–Thessaly (T.T., G.G.), Trikala, Greece.

The authors report no conflict of interest.Received November 1, 2010; accepted June 20, 2011.Address correspondence to Alexander Tsarouhas, M.D., Ph.D.,

16 Omogenon Amerikis St, 42200, Kalambaka, Trikala, Greece.E-mail: tsarouhas_a@yahoo.gr

© 2011 by the Arthroscopy Association of North America

0749-8063/10655/$36.00doi:10.1016/j.arthro.2011.06.028

1654 Arthroscopy: The Journal of Arthroscopic and Related Surg

ions, collagen orientation, and insertion sites.1,2 Conse-uently, the double-bundle technique was introducedn the last few decades in an attempt to replicate theomplex geometry and mechanics of the nativeigament and to address the alleged disadvantagesf the conventional single-bundle technique. Theovel technique is expected to provide superiorlinical outcomes by controlling both anteroposte-ior tibial translation and tibial rotation more effi-iently.3-6

The findings of in vitro, intraoperative, and in vivostudies using static laxity testing, which assessed theeffectiveness of different ACL reconstruction tech-niques in restoring knee kinematics, were contradic-tive.7-9 Numerous studies have also investigated thelterations in knee kinematics after ACL reconstruc-ion under dynamic loading conditions.10-15 However,

current in vivo research on the differences in rotational

ery, Vol 27, No 12 (December), 2011: pp 1654-1662

iofTa

1655TIBIAL ROTATION AFTER ACL RECONSTRUCTION

knee laxity between the single- and double-bundle tech-niques is still limited.16 Therefore the kinematic superi-ority of the double-bundle technique remains to be es-tablished in vivo, leading some investigators to argue itspotential benefits especially when considering its in-creased cost and surgical complexity.17

In a previous study by our group, the rotational kneelaxity after single- and double-bundle ACL reconstruc-tion was examined during a 60°-pivoting maneuver froma standing position with the knee in full extension.16 Nosignificant differences in tibial rotation were estab-lished between the 2 ACL-reconstructed groups.However, the kinematic behavior of the knee is taskdependent. Forces on the intact ACL during cuttingand acceleration-deceleration activities are signifi-cantly higher compared with level walking.18 It is,therefore, intriguing to investigate whether highlydemanding activities, such as stair ascending ordescending combined with immediate pivoting, re-sult in higher tibial torsion and whether a particularsurgical technique could provide better kinematicoutcomes in this setting.

The purpose of this study was to evaluate in vivothe differences in tibial rotation between single- anddouble-bundle ACL-reconstructed knees under com-bined loading conditions. Two different pivoting taskswere selected to subject the knees to substantial rota-tional stress simulating highly demanding activities.The first task included walking, 60° pivoting, and stairascending, and the second included stair descending,60° pivoting, and walking. On the basis of previousfindings, our hypothesis was that tibial rotationwould not differ significantly between the single-and double-bundle ACL-reconstructed groups.

METHODS

A total of 52 male volunteers were allocated into 4groups. The double-bundle group consisted of 14 pa-tients who underwent successful (based on clinicalexamination and patient feedback) ACL reconstruc-

TABLE 1.

Control (n � 12) ACL Defi

Age (mean � SD) (yr) 30.0 � 5.7 28Body mass (kg) (mean � SD) 71.3 � 17.2 77Body mass index (kg/m2)

(mean � SD)24.6 � 4.7 25

Follow-up (mean � SD) (mo) —

No. of meniscectomies — —

tion with hamstring tendon autograft. The single-bundle group consisted of 14 patients who weretreated successfully with ACL reconstruction withquadruple hamstring tendon autograft. All the recon-structions were performed in 2007. Exclusion criteriafor the reconstructed groups included other ligamen-tous (posterior cruciate, medial, or lateral) injury orbone and chondral lesions in the same knee as as-sessed by magnetic resonance imaging and clinicalexamination, as well as any history of pain or trauma tothe contralateral knee. Patients with simultaneous men-iscectomy in the injured knee were included in the study,provided that less than two-thirds of the meniscalvolume was resected as confirmed during arthros-copy. All the ACL-reconstructed patients had com-pleted their rehabilitation protocol and returned toeveryday activities and recreational or competitivesports. The ACL-deficient group consisted of 12 pa-tients with chronic ACL deficiency (�1 year). Rup-ture of the ligament was confirmed by magnetic res-onance imaging and clinical examination. Copers(e.g., ACL-deficient participants who returned tohigh-level physical activity without problems) werenot excluded from the study. Specifically, all theACL-deficient participants reported occasional symp-toms of instability. However, 7 of them participatedroutinely in competitive sports and reported no inten-tion to undergo surgical reconstruction of the liga-ment. The remaining 5 were examined while waitingfor ligament reconstruction. The control group con-sisted of 12 volunteers with a negative history ofneuromusculoskeletal injury or any other functionaldeficit. All the participants signed an informed con-sent form approved by the institutional review boardto participate in the study.

The 4 groups did not differ significantly (P � .05)n terms of age, body mass, body mass index, durationf follow-up, and number of meniscectomies per-ormed. Patient characteristics are shown in Table 1.he minimum time interval between surgery and ex-mination was 1 year.

nt Profile

n � 12) Single Bundle (n � 14) Double Bundle (n � 14)

.5 26.6 � 7.6 28.3 � 6.9

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1656 A. TSAROUHAS ET AL.

Surgical Technique

All the reconstructions were performed or directlysupervised by the same surgeon (M.I.). The surgicaltechniques for single- and double-bundle ACL recon-structions have been previously described in detail.16

In brief, for the double-bundle procedure, 2 femoraland 2 tibial tunnels were created. The femoral tunnelswere drilled at 110° of knee flexion through the an-teromedial (AM) portal for the AM bundle and anaccessory medial portal for the posterolateral (PL)bundle. Both the femoral and tibial tunnels weredrilled through the insertion sites of the native ACLbundles. The grafts were secured with EndoButtons(Smith & Nephew Endoscopy, Andover, MA) on thefemoral side and bioabsorbable interference screwsand staples for post-fixation on the tibial side. Theywere tensioned by maximum manual power and fixedon the tibia at 45° of knee flexion for the PL bundle and0° for the AM bundle. In general, the degree of kneeexion for graft fixation varies considerably among or-

hopaedic surgeons, ranging from 0° to 90° for the AMundle and 20° to 45° for the PL bundle.19 The graft

fixation option used in our series is among the optionssuggested in the literature. For the single-bundle tech-nique, the femoral tunnel was drilled between the inser-tions of the native ACL bundles through the AM portal

with the knee at 110° of flexion. The graft was manuallytensioned and fixed at 10° of knee flexion.

Testing Procedure

Clinical evaluation of the ACL-reconstructed and-deficient participants preceded the biomechanicaldata collection. Blinded clinical and kinematic exam-inations were performed by 1 examiner who per-formed the Lachman, anterior drawer, and pivot-shifttests; obtained Lysholm and Tegner scores; and car-ried out the experimental protocol, which was thesame for every participant. The participants wereasked to perform 2 maneuvers at self-selected speedand in a randomized order. In the first task, they wereasked to walk toward a 2-step stair positioned in frontof a force platform with an approaching angle of 30°.Consequently, they had to pivot 60° with the support-ing leg and ascend the stairs vertically. Maximumknee rotational loading was achieved by instructingthem to keep the supporting foot on the floor until thecontralateral foot contacted the first step (Fig 1). In asimilar fashion, the second maneuver included a de-scending movement, landing, and turning at 60° (Fig2). The points of touchdown for both legs weremarked to provide a target for the 60° of rotation. Theexamined maneuvers were performed at self-selected

FIGURE 1. First movement:(A) approaching and (B) pivot-ing and stair ascending. Thesignificant external rotation ofthe left knee while in full ex-tension should be noted.

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1657TIBIAL ROTATION AFTER ACL RECONSTRUCTION

speed after some pilot testing. Initially, we controlledthe speed of the patients, but the movement for someof them was not “natural.” Because these were de-manding movements, it was difficult for the partici-pants to move at specific speeds. Therefore they wereall asked to move at self-selected speed.

The subjects were encouraged to pivot as rapidlyand intensely as possible to achieve homogeneity inthe tasks performed. Real-time inspection of the videoand foot kinematic data was used to exclude trials thatdid not fulfill the previously mentioned requirements.After pivoting, the subjects continued to ascend untilthey reached the top of the stair for the first maneuverand kept walking for at least 2 strides for the second.At least 5 successful trials were recorded for each side.

Data Collection

The motion of the lower extremities was tracked by anoptoelectronic 3-dimensional motion analysis system(Vicon MX; Oxford Metrics Group, Oxford, UnitedKingdom). The system used 8 cameras (MX40�; Ox-ord Metrics Group) (4 megapixels), sampling at a fre-uency of 100 Hz. A total of 24 retro-reflective skinarkers (9 mm) were attached to the pelvis and lower

FIGURE 2. Second movement:(A) descending and (B) pivot-ing and walking. The rightknee is stressed in external ro-tation while in full extension.

xtremities of each subject according to the model de-

cribed by Schwartz and Rozumalski.20 This model isinitially based on the standard Davies model21 for stati-cally calculating the approximate positions of the lowerjoints but subsequently uses a cluster of markers tofunctionally optimize the knee and hip joint centers andaxes of rotation. This method has been shown to provideprecise hip and knee joint centers of rotation (within 1 to3 mm and 3 to 9 mm, respectively) and knee axisalignment (deviation of 2°).20

A force platform (type 4060-10; Bertec, Worthington,OH) was flush mounted in the center of the calibratedvolume to collect ground reaction force (GRF) data.Only the pivoting leg was on the force plate during eachtrial. GRF data were collected at a sampling frequency of1,000 Hz and synchronized with the Vicon MX system.Kinematic data were smoothed by use of a Woltringfilter at a cutoff frequency of 6 Hz. Joint loading wascalculated by the combination of kinematic, anthropo-metric, and GRF data. Knee joint moment was normal-ized to body mass.

Statistical Analysis

Statistical analysis was performed with the SPSSsoftware package, version 15 (SPSS, Chicago, IL).

The evaluation period for both maneuvers began from

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1658 A. TSAROUHAS ET AL.

touchdown of the supporting leg on the force platformand ended with touchdown of the contralateral leg.The 2 variables evaluated were the maximum range ofinternal-external tibial rotation and the maximum kneerotational moment. A paired t test between the left andight sides of the control group showed no significantifferences, and therefore the left side was used foromparisons. Side-to-side differences in the examinedariables for the 4 groups were assessed by use ofepeated-measures analysis of variance. One-waynalysis of variance was used to examine between-roup differences, on the affected side, for both vari-bles under evaluation. A power analysis was alsoerformed. The significance level was set at P � .05.

RESULTS

linical Evaluation and Functional Scores

The same surgeon conducted the clinical evaluationM.I.). The anterior drawer, Lachman, and pivot-shiftests were negative in all ACL-reconstructed patients.here was no extension deficit in any of the ACL-

econstructed patients, and knee flexion averaged 130°ithout any significant differences between the 2roups. On the contrary, all the ACL-deficient patientsad positive (minimum, �2) anterior drawer, Lach-an, and pivot-shift tests. The Lysholm score did not

iffer significantly between the single-bundle (95.8 �

TABLE 2. Tibial Rotatio

Control (n � 12) ACL Deficient

Ascending (°)Unaffected knee 12.9 � 2.9 14.0 � 5Affected knee — 14.3 � 3

Descending (°)Unaffected knee 14.2 � 2.0 15 � 3Affected knee — 15.3 � 3

Data are given as mean � standard deviation.

TABLE 3. Maximum Knee Rotation

Control (n � 12) ACL Deficien

Ascending (Nmm/kg)Unaffected knee 201 � 55 169 �Affected knee — 166 �

Descending (Nmm/kg)Unaffected knee 198 � 65 283 �Affected knee — 268 �

Data are given as mean � standard deviation.* Significant at .05 level.

.9), double-bundle (95.1 � 4.2), and control groups96 � 2.3) (minimum P � .78). However, the Lysh-lm score of the ACL-deficient group (82.7 � 11.4)as significantly lower compared with all otherroups (P � .01; observed power, 0.91). The meanegner score in the deficient group was 5.7, whichas significantly lower (P � .01; observed power,.82) than that in both the single- and double-bundleroups (7.3 and 7.6, respectively).

inematic and Kinetic Assessment

Kinematic and kinetic data were analyzed from aotal of 1,040 trials for both maneuvers (52 subjects �

maneuvers � 5 trials � 2 sides). Group means andtandard deviations of the examined variables—tibialotation and rotational moment—are presented in Ta-les 2 and 3, respectively. Tibial rotation angles didot differ significantly among the 4 groups (P � .331nd P � .851 for the ascending and descending ma-euvers, respectively; observed power, 0.30 and 0.29,espectively) (Fig 3). In both maneuvers the highestibial rotation was recorded in the ACL-deficientroup. In the descending maneuver, tibial rotation forhe single- and double-bundle groups was lower com-ared with the control group (1.5° and 0.3°, respec-ively). Side-to-side differences were also not signifi-ant (P � .216 and P � .371 for the ascending andescending maneuvers, respectively; observed power,

ng Examined Maneuvers

2) Single Bundle (n � 14) Double Bundle (n � 14)

14.1 � 4.8 12.1 � 2.913.2 � 4.7 12.6 � 3.9

14.1 � 4.3 14.3 � 4.112.7 � 3.8 13.9 � 4.3

ment During Examined Maneuvers

12) Single Bundle (n � 14) Double Bundle (n � 14)

200 � 71 187 � 50159 � 54* 152 � 77*

243 � 61 274 � 72231 � 53 259 � 73

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1659TIBIAL ROTATION AFTER ACL RECONSTRUCTION

0.35 and 0.36, respectively). Generally, tibial rotationon the affected side was lower than that on the unaf-fected side in the ACL-reconstructed groups, with theexception of the double-bundle group during theascending maneuver. On the contrary, in the ACL-deficient group the affected side showed higher tibialrotation values.

In both maneuvers, maximum knee rotational mo-ment values were recorded near the ending of theswinging phase. Rotational moments did not differsignificantly between the affected sides of ACL-deficient and -reconstructed patients and the controlgroup with both ascending and descending maneuvers(P � .418 and P � .290, respectively; observedower, 0.27 and 0.32, respectively) (Fig 4). Rotationaloments applied on the affected side were constantly

FIGURE 3. Tibial rotation (mean � standardeviation) of examined groups.

ower compared with the unaffected side. In the as-ending maneuver, the rotational moments of the af-ected sides were significantly lower by 20.5% and8.7% compared with their intact counterparts in theingle-bundle (P � .015) and double-bundle (P � .05)roups, respectively (observed power, 0.78). In theescending maneuver, the rotational moments wereot significantly different between sides (P � .192;bserved power, 0.31).

DISCUSSION

In this study, tibial rotation in single- and double-undle ACL-reconstructed patients was investigatedn vivo with 2 highly demanding activities. Specifi-ally, 3-dimensional kinematic and kinetic analysis

FIGURE 4. Rotational moments (mean � stan-dard deviation) of examined groups.

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1660 A. TSAROUHAS ET AL.

was used to quantify the range of internal-externaltibial rotation and the maximum rotational moment ofACL-deficient and -reconstructed patients. Our analysisconfirmed our primary hypothesis, showing no signifi-cant differences in tibial rotation angles and momentsbetween the single- and double-bundle groups. However,rotational moments on the affected side of the 2 recon-structed groups were significantly lower compared withtheir intact counterparts.

We examined 2 maneuvers. One task includedwalking, 60° pivoting, and stair ascending, and theother included descending, 60° pivoting, and walking,focusing on the pivoting maneuver. Both of thesetasks included cutting and pivoting, which are rela-tively close to the demanding tasks of competitivesports, such as basketball and football, to which themajority of patients who undergo surgery wish toreturn.22 During these tasks, the supporting knee wasn full extension. Between 0° and 30° of knee flexion,he PL bundle primarily controls combined rotationaloads.23,24 Therefore, because in the double-bundle tech-ique the PL bundle is augmented to the conventionallyeconstructed AM bundle, testing in the extended-kneeosition allows for assessment of its potential contribu-ion in limiting residual knee laxity. However, furtheriomechanical testing under different loading condi-ions or knee flexion angles is needed, because ourndings cannot be extrapolated to other movements,uch as a single-leg hop or an anterior lunge, that arenown to impose considerable loads on the ACL. Ithould also be noted that our study examined isolatedransverse-plane tibial rotation. Previous studies haveimilarly investigated the effect of ACL injury andeconstruction on tibial rotation.13-15 The latter, how-ver, must be distinguished from the pivot-shift mech-nism examined in most clinical studies, which in-olves a combination of anterior tibial translation andotation.

Our results indicated that double-bundle ACL-econstructed knees did not differ significantly inerms of tibial rotation compared with the single-undle technique. There is still significant controversyegarding the issue of rotational knee laxity after ACLeconstruction. In a study using electromagnetic sen-ors, Yagi et al.5 found better pivot-shift control of

complex instability in patients with double- comparedwith single-bundle reconstructions. However, mount-ing evidence from both in vitro and in vivo studies isin agreement with our results. In a recent cadavericstudy, Ho et al.9 found equal kinematics betweenentrally placed anatomic single-bundle and 4-tunnel

ouble-bundle ACL reconstructions. Using computer

avigation intraoperatively, Ferretti et al.8,25 foundthat anatomic double-bundle reconstruction did notfurther reduce internal and external tibial rotation atdifferent degrees of flexion compared with isolatedAM bundle reconstruction. Our findings also showedthat tibial rotation on the affected side in the ACL-reconstructed groups was lower than that on the intactside, with the exception of the ascending maneuver inthe double-bundle group. Steckel et al.26 have alsoocumented a decrease in internal-external knee laxityfter single- and double-bundle ACL reconstructionsompared with the intact state. In our case, althoughhe possibility that a subtle difference in confidenceetween sides accounts for these findings cannot bexcluded, it is possible that surgery itself has led tover-tightening of the knee.Kinematic analysis has been used before to inves-

igate in vivo the effect of ACL reconstruction onibial rotation. Ristanis et al.27 and Georgoulis et al.13

found abnormal rotational kinematics in the ACL-reconstructed knee compared with the contralateralintact knee during a 90°-pivoting maneuver after stairdescent, which resembled one of the examined ma-neuvers in our study. Their findings were not in agree-ment with our results. However, there were certaindifferences between the studies. First, different grafttypes were used. Differences in functional knee kine-matics and kinetics were established by Webster etal.28 between patellar and hamstring tendon ACL re-constructions. Second, in our ACL reconstructions weadopted a more horizontal graft orientation that hasbeen shown to control rotational knee laxity moreefficiently in varying degrees of flexion.29-31 In gen-eral, biomechanical studies investigating ACL kine-matics present significant variability in terms of sur-gical technique, graft type, fixation methods, andpatient characteristics. Assessment methods also con-tribute to this variability. In vivo studies, for example,present difficulties particularly in achieving accuratemeasurements of bone movement. As a consequence,in vitro studies are unable to precisely replicate theactual loading conditions of the knee. Intraoperat-ive studies, on the other hand, can hardly comprisethe effect of the graft incorporation and remodelingprocess on knee kinematics. We believe that much ofthe controversy regarding knee kinematics after ACLreconstruction is attributed to the variability of exist-ing studies.

Our analysis showed that the values of tibial rota-tion were higher but not significantly different in theACL-deficient group compared with the other 3

groups. This finding is not in accordance with previ-

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1661TIBIAL ROTATION AFTER ACL RECONSTRUCTION

ous biomechanical studies. A possible explanationmay be that copers were not excluded from our study.Using gait analysis in patients with ACL deficiency,Patel et al.32 found that absolute knee laxity measure-ments did not correlate with dynamic knee functionand that patients with greater-than-normal quadricepsstrength performed high-stress activities in a morenormal fashion compared with those with less-than-normal strength. Similarly, Tsepis et al.33 found asignificant effect of hamstring weakness among ACL-deficient patients in their ability to compensate forinstability symptoms. Findings of recent studies, how-ever, were in agreement with our findings. In a cadav-eric study, for example, Diermann et al.34 did notdentify any effect of ACL deficiency on rotationalnee kinematics.Rotational moment values that were recorded in the

escending maneuver (up to 283 Nmm/kg) were sub-tantially higher than in the ascending maneuver (201mm/kg), indicating that the former is more demand-

ng for the knee joint. Rotational moments achieved inhis maneuver were also higher than during a pivotinganeuver from a standing position (260 Nmm/kg).ompared with walking, stair descending places andditional axial force on the knee. In addition, eccen-ric quadriceps activity during stair descending in-reases strains on the ACL by causing anterior tibialisplacement and an increase in joint compressiveorce. The latter has been found to increase ACLoading by posteriorly displacing the femur in relationo the tibia coupled with the sliding of the lateralemoral condyle over the tibial plateau, which in turnesults in rotational translation of the tibia.35 There-

fore the accumulation in rotational forces due to thesubsequent 60°-pivoting maneuver is expected toelicit, if present, increased tibial rotation values. Find-ings of this study also showed a substantial differencein rotational moment values of the control group com-pared with the other 3 groups in the descending ma-neuver. However, there is little evidence to establish arobust theory to explain this finding. It is possible thatthe absence of hamstrings in the ACL-reconstructedpatients and the ACL in the deficient patients,which are both antagonists to the quadriceps, pre-disposes patients to increased rotational momentsand angles in these groups based on the mechanismdescribed previously.

Rotational moments on the affected side of the 2reconstructed groups were constantly lower comparedwith the intact side. Similar findings were noted aftera 60°-pivoting maneuver from a standing position,

suggesting a difference in confidence between the 2

sides. Although rotational moments during the as-cending maneuver were not the highest recorded,the reduction in moment values on the affected side ofthe ACL-reconstructed participants was significant.We believe that it is the nature of the specific maneu-ver that allows adjacent joints to absorb the overallrotational loading, thus reducing joint loading andprotecting the knee.

Our study has certain limitations. First, the ability of3-dimensional kinematic analysis to calculate effec-tively the relative movement of bones by use of skinmarkers has been questioned in the past. Nevertheless,we believe that the advanced kinematic model withdynamic joint calibration implemented in our studysignificantly reduces the kinematic error comparedwith the standard Davies model.21 Second, examina-ion for knee stability in our study did not includeT-1000 testing (MEDmetric, San Diego, CA). How-

ver, the functional and stability conditions of theatients’ knees were evidenced by numerous otherlinical and functional tests. Finally, the analysis pre-ented involved a homogeneous group of patients whonderwent ACL reconstruction by use of the sameraft type and fixation technique. Therefore the con-lusions drawn cannot be applied to all different ACLeconstruction techniques that are currently available.

CONCLUSIONS

High-intensity activities combining stair ascending orescending with pivoting produce similar tibial rotationn single- and double-bundle ACL-reconstructed pa-ients. During such maneuvers, the reconstructed kneeay be subjected to significantly lower rotational loads

ompared with the intact knee.

REFERENCES

1. van Eck CF, Lesniak BP, Schreiber VM, Fu FH. Anatomicsingle- and double-bundle anterior cruciate ligament recon-struction flowchart. Arthroscopy 2010;26:258-268.

2. Petersen W, Zantop T. Anatomy of the anterior cruciate liga-ment with regard to its two bundles. Clin Orthop Relat Res2007;454:35-47.

3. Siebold R, Dehler C, Ellert T. Prospective randomized com-parison of double-bundle versus single-bundle anterior cruci-ate ligament reconstruction. Arthroscopy 2008;24:137-145.

4. Muneta T, Koga H, Mochizuki T, et al. A prospective ran-domized study of 4-strand semitendinosus tendon anteriorcruciate ligament reconstruction comparing single-bundle anddouble-bundle techniques. Arthroscopy 2007;23:618-628.

5. Yagi M, Kuroda R, Nagamune K, Yoshiya S, Kurosaka M.

Double-bundle ACL reconstruction can improve rotationalstability. Clin Orthop Relat Res 2007;454:100-107.

1

1

1

2

2

2

2

2

2

2

2

2

2

3

3

1662 A. TSAROUHAS ET AL.

6. Yasuda K, Tanabe Y, Kondo E, Kitamura N, Tohyama H. Ana-tomic double-bundle anterior cruciate ligament reconstruction.Arthroscopy 2010;26:S21-S34 (Suppl).

7. Yagi M, Wong EK, Kanamori A, Debski RE, Fu FH, Woo SL.Biomechanical analysis of an anatomic anterior cruciate liga-ment reconstruction. Am J Sports Med 2002;30:660-666.

8. Ferretti A, Monaco E, Labianca L, Conteduca F, De Carli A.Double-bundle anterior cruciate ligament reconstruction: Acomputer-assisted orthopaedic surgery study. Am J Sports Med2008;36:760-766.

9. Ho JY, Gardiner A, Shah V, Steiner ME. Equal kinematicsbetween central anatomic single-bundle and double-bundleanterior cruciate ligament reconstructions. Arthroscopy 2009;25:464-472.

10. Deneweth JM, Bey MJ, McLean SG, Lock TR, Kolowich PA,Tashman S. Tibiofemoral joint kinematics of the anterior cru-ciate ligament-reconstructed knee during a single-legged hoplanding. Am J Sports Med 2010;38:1820-1828.

11. Tashman S, Collon D, Anderson K, Kolowich P, Anderst W.Abnormal rotational knee motion during running after anteriorcruciate ligament reconstruction. Am J Sports Med 2004;32:975-983.

12. Scanlan SF, Chaudhari AM, Dyrby CO, Andriacchi TP. Dif-ferences in tibial rotation during walking in ACL reconstructedand healthy contralateral knees. J Biomech 2010;43:1817-1822.

13. Georgoulis AD, Ristanis S, Chouliaras V, Moraiti C, StergiouN. Tibial rotation is not restored after ACL reconstruction witha hamstring graft. Clin Orthop Relat Res 2007;454:89-94.

4. Chouliaras V, Ristanis S, Moraiti C, Stergiou N, GeorgoulisAD. Effectiveness of reconstruction of the anterior cruciateligament with quadrupled hamstrings and bone-patellar ten-don-bone autografts: An in vivo study comparing tibial inter-nal-external rotation. Am J Sports Med 2007;35:189-196.

5. Chouliaras V, Ristanis S, Moraiti C, Tzimas V, Stergiou N,Georgoulis AD. Anterior cruciate ligament reconstruction with aquadrupled hamstrings tendon autograft does not restore tibialrotation to normative levels during landing from a jump andsubsequent pivoting. J Sports Med Phys Fitness 2009;49:64-70.

16. Tsarouhas A, Iosifidis M, Kotzamitelos D, Spyropoulos G,Tsatalas T, Giakas G. Three-dimensional kinematic and ki-netic analysis of knee rotational stability after single- anddouble-bundle anterior cruciate ligament reconstruction. Ar-throscopy 2010;26:885-893.

17. Brophy RH, Wright RW, Matava MJ. Cost analysis of con-verting from single-bundle to double-bundle anterior cruciateligament reconstruction. Am J Sports Med 2009;37:683-687.

18. Markolf KL, Burchfield DM, Shapiro MM, Cha CW, Finer-man GA, Slauterbeck JL. Biomechanical consequences ofreplacement of the anterior cruciate ligament with a patellarligament allograft. Part II: Forces in the graft compared withforces in the intact ligament. Bone Joint Surg Am 1996;78:1728-1734.

9. Zantop T, Kubo S, Petersen W, Musahl V, Fu FH. Currenttechniques in anatomic anterior cruciate ligament reconstruc-tion. Arthroscopy 2007;23:938-947.

0. Schwartz MH, Rozumalski A. A new method for estimating

joint parameters from motion data. J Biomech 2005;38:107-116.

1. Davies R, Ounpuu S, Tyburski D, Gage J. A gait analysis datacollection and reduction technique. Hum Mov Sci 1991;10:575-587.

2. Swirtun LR, Eriksson K, Renström P. Who chooses anteriorcruciate ligament reconstruction and why? A 2-year prospec-tive study. Scand J Med Sci Sports 2006;16:441-446.

3. Amis AA, Dawkins GP. Functional anatomy of the anteriorcruciate ligament. Fibre bundle actions related to ligamentreplacements and injuries. J Bone Joint Surg Br 1991;73:260-267.

4. Zantop T, Herbort M, Raschke MJ, Fu FH, Petersen W. Therole of the anteromedial and posterolateral bundles of theanterior cruciate ligament in anterior tibial translation andinternal rotation. Am J Sports Med 2007;35:223-227.

5. Ferretti A, Monaco E, Labianca L, De Carli A, Maestri B,Conteduca F. Double-bundle anterior cruciate ligament recon-struction: A comprehensive kinematic study using navigation.Am J Sports Med 2009;37:1548-1553.

6. Steckel H, Murtha PE, Costic RS, Moody JE, Jaramaz B, Fu FH.Computer evaluation of kinematics of anterior cruciate ligamentreconstructions. Clin Orthop Relat Res 2007;463:37-42.

7. Ristanis S, Giakas G, Papageorgiou CD, Moraiti T, StergiouN, Georgoulis AD. The effects of anterior cruciate ligamentreconstruction on tibial rotation during pivoting after descend-ing stairs. Knee Surg Sports Traumatol Arthrosc 2003;11:360-365.

8. Webster KE, Gonzalez-Adrio R, Feller JA. Dynamic jointloading following hamstring and patellar tendon anterior cru-ciate ligament reconstruction. Knee Surg Sports TraumatolArthrosc 2004;12:15-21.

9. Loh JC, Fukuda Y, Tsuda E, Steadman RJ, Fu FH, Woo SL.Knee stability and graft function following anterior cruciateligament reconstruction: Comparison between 11 o’clock and10 o’clock femoral tunnel placement. 2002 Richard O’ConnorAward paper. Arthroscopy 2003;19:297-304.

0. Yamamoto Y, Hsu WH, Woo SL, Van Scyoc AH, Takakura Y,Debski RE. Knee stability and graft function after anteriorcruciate ligament reconstruction: A comparison of a lateral andan anatomical femoral tunnel placement. Am J Sports Med2004;32:1825-1832.

1. Tsuda E, Ishibashi Y, Fukuda A, Tsukada H, Toh S. Compa-rable results between lateralized single- and double-bundleACL reconstructions. Clin Orthop Relat Res 2009;467:1042-1055.

32. Patel RR, Hurwitz DE, Bush-Joseph CA, Bach BR Jr, Andri-acchi TP. Comparison of clinical and dynamic knee function inpatients with anterior cruciate ligament deficiency. Am JSports Med 2003;31:68-74.

33. Tsepis E, Vagenas G, Giakas G, Georgoulis A. Hamstringweakness as an indicator of poor knee function in ACL-deficient patients. Knee Surg Sports Traumatol Arthrosc 2004;12:22-29.

34. Diermann N, Schumacher T, Schanz S, Raschke MJ, PetersenW, Zantop T. Rotational instability of the knee: Internal tibialrotation under a simulated pivot shift test. Arch OrthopTrauma Surg 2009;129:353-358.

35. Boden BP, Sheehan FT, Torg JS, Hewett TE. Noncontact

anterior cruciate ligament injuries: Mechanisms and risk fac-tors. J Am Acad Orthop Surg 2010;18:520-527.