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Resume Introduction L’analyse des causes d’echec d’une ligamentoplastie du LCA doit permettre de choisir la technique la plus adaptee lors de la reprise chirurgicale afin d’assurer au patient un bon controle de la stabilite rotatoire et de diminuer les risques de ruptures iteratives. Objectif L’objectif de ce travail est d’evaluer les plasties anterolaterales (PAL) dans les reprises de ligamentoplasties du LCA. Hypothese L’hypothese de ce travail etait que les PAL realisees lors des chirurgies de revision du LCA, permettaient d’assurer un bon controle du ressaut sans augmenter les risques de complication. Materiel et methodes Il s’agit d’une etude multicentrique, prospective (sur 24 mois) et retrospective (minimum 3 ans de recul) fondee sur 349 patients, 283 hommes et 66 femmes. Les criteres d’inclusion sont des patients pour lesquels une indication chirurgicale de revision du LCA avec plastie intra-articulaire et PAL a ete retenu suite a un echec de plastie du LCA par autogreffe avec un LCP intact. Les criteres d’exclusion sont les reconstruction du LCA de 1 re intention et les lesions peripheriques mediales et/ou laterale associees. Les patients ont eu une evaluation clinique et radiographique pre- et postoperatoire. Le score IKDC preoperatoire etait en moyenne de 56,5 ± 15,5 avec 96 % de score IKDC C ou D. Resultats Le taux de complications postoperatoires precoces etait de 5 % et postoperatoires tardives de 10,5 %. Au dernier recul, dans 97 % des cas le test de Lachman avait un arret dur. Le ressaut rotatoire etait positif dans 1 % des cas. Le score IKDC subjectif moyen etait de 84,5 ± 13 dont 86,5 % de classe A ou B. Les signes d’arthrose radiographique etaient stables au dernier recul sur les compartiments femorotibial lateral et femoropatellaire, mais en augmentation de 9,7 a 21,2 % sur le compartiment femorotibial medial. Le taux de reruptures etait de 1,2 % et le taux de re-intervention secondaire de 5,4 %. Conclusion La laxite anterieure au dernier recul est similaire aux autres series de revision de la litterature mais le controle du ressaut et le taux de rupture iterative sont inferieurs. Les PAL font partie des techniques a envisager dans l’arsenal therapeutique des chirurgies de reprise du LCA. Type d’etude Etude retrospective et prospective de cohorte niveau IV.

Resume Introduction Les ancillaires personnalisees dans l’arthroplastie totale de genou se definissent comme une technique innovante pour faciliter le geste operatoire. Neanmoins se pose la question encore controversee de la precision de ces guides sur mesure pour aligner les implants. L’objectif de cette etude a ete d’analyser les resultats radiographiques postoperatoires de 50 protheses totales du genou (PTG), en analysant plus particulierement la pente tibiale de l’implant, difficilement controlable en cours d’intervention. Notre hypothese etait que les guides personnalises determinent de facon variable la pente tibiale. Materiel et methode Cinquante PTG d’une serie prospective et continue ont fait l’objet d’une programmation personnalisee Signature® (Biomet) basee sur une IRM. La pente tibiale posterieure planifiee etait de 2°. L’analyse radiologique postoperatoire a ete realisee par un observateur independant a partir de cliches numeriques standardises. Un test de reproductibilite des mesures radiographiques a ete pratique sur 20 cas. La corticale posterieure du tibia a servi de reference pour mesurer la pente tibiale. Une deviation de ± 2° par rapport a la valeur cible a ete consideree comme une imprecision. Resultats La pente tibiale d’implantation etait de 2° ± 2° dans 70 % des cas. Dans 30 % des cas, une imprecision etait rapportee avec 11 pentes tibiales d’implantation excessives (maximum 9°) et 4 pentes inversees, (maximum −6°). L’angle HKA postoperatoire etait de 0° ± 3° dans 88 % des cas avec une deviation maximale en varus de 9°. Conclusion Nos resultats corroborent l’hypothese d’une moins bonne precision sur la pente tibiale en accord avec les donnees recentes issues de la litterature. L’instrumentation specifique a en revanche montre sa capacite a controler l’alignement frontal. Niveau de preuve IV. Etude de cohorte.

Resume Introduction Les plasties anterolaterales (PAL) sont utilisees pour diminuer le risque de rupture iterative apres reconstruction du ligament croise anterieur (LCA) chez les patients a risque. Ces plasties ajoutent un geste a la greffe isolee du LCA qui peut augmenter le temps operatoire et perturber les suites operatoires. L’objectif de cette etude etait d’evaluer le taux de complications precoces. L’hypothese etait que les plasties anterolaterales associees a une plastie du LCA n’augmentent pas le taux de complications par rapport aux plasties isolees. Materiel et methodes Il s’agit d’une etude multicentrique, prospective portant sur 392 patients dont 70 % d’hommes, âges en moyenne de 29,9 ans, operes d’une plastie du LCA avec PAL associee. L’ensemble des evenements indesirables ont ete releves. Resultats La duree moyenne d’hospitalisation a ete de 2 jours avec 46 % de chirurgie ambulatoire. La marche etait acquise en 27 jours en moyenne avec un avantage pour les patients operes avec une technique aux ischio-jambiers. Le taux de complication postoperatoire precoce etait de 12 % dont 1,7 % specifiques a la PAL : douleur, hematome, raideur en flexion et extension, infection. Cinq pour cent de re-interventions ont ete observees la premiere annee avec une majorite d’arthrolyse pour flexum. Le taux de rupture iterative etait de 2,8 % a l’issue de la premiere annee. Discussion Les complications des PAL associees aux plasties intra-articulaires ne sont pas plus importantes que pour les plasties intra-articulaires isolees, sans augmentation du taux d’infection ni de raideur. Les complications liees a la PAL sont faibles, 1,7 %, et sont a mettre en rapport avec des erreurs techniques de fixation ayant engendre des conflits avec les parties molles laterales. Niveau de preuve Niveau IV, etude multicentrique prospective.

Introduction Lateral tenodesis (LT) is performed to limit the risk of iterative tear following anterior cruciate ligament (ACL) reconstruction in at-risk patients. By adding an extra procedure to isolated ACL graft, LT reconstruction increases operating time and may complicate postoperative course. The objective of the present study was to evaluate the rate of early complications. The study hypothesis was that associating ALL reconstruction to ACL reconstruction does not increase the complications rate found with isolated ACL reconstruction. Material and methods A prospective multicenter study included 392 patients: 70% male; mean age, 29.9 years; treated by associated ACL and LT reconstruction. All adverse events were inventoried. Results Mean hospital stay was 2 days, with 46% day-surgery. Walking was resumed at a mean 27 days, with an advantage for patients treated by the hamstring technique. The early postoperative complications rate was 12%, with 1.7% specifically implicating LT reconstruction: pain, hematoma, stiffness in flexion and extension, and infection. There was a 5% rate of surgical revision during the first year, predominantly comprising arthrolysis for extension deficit. The 1-year recurrence rate was 2.8%. Discussion The complications rate for combined intra- and extra-articular reconstruction was no higher than for isolated intra-articular ACL reconstruction, with no increase in infection or stiffness rates. The rate of complications specific to ALL reconstruction was low, at 1.7%, and mainly involved fixation error causing lateral soft-tissue impingement. Level of evidence IV, prospective multicenter study.

Background A careful analysis of the reasons for ACL reconstruction failure is essential to selection of the optimal surgical revision technique designed to ensure good rotational stability and to minimise the risk of re-rupture. Objective To evaluate anterolateral ligament (ALL) stabilisation during revision ACL reconstruction. Hypothesis ALL stabilisation during revision ACL reconstruction provides good rotational stability without increasing the risk of complications. Material and methods This multicentre study included 349 patients, 151 retrospectively and 198 prospectively. There were 283 males and 66 females. Inclusion criteria were an indication for revision ACL reconstruction surgery with combined intra-articular reconstruction and ALL stabilisation after failed autograft ACL reconstruction, and intact PCL. Exclusion criteria were primary ACL reconstruction and concomitant peripheral medial and/or lateral lesions. Each patient underwent a clinical and radiographic evaluation before and after revision surgery. Before revision surgery, the mean IKDC score was 56.5 ± 15.5 and 96% of patients were IKDC C or D. Results Rates were 5.0% for early and 10.5% for late postoperative complications. Lachmann's test had a hard stop at last follow-up in 97% of patients. The pivot-shift test was positive in 1% of patients. The mean subjective IKDC score was 84.5 ± 13.0 and 86.5% of patients were IKDC A or B. The proportions of patients with radiographic knee osteoarthritis at last follow-up was unchanged for the lateral tibio-femoral and patello-femoral compartments but increased by 9.7% to 21.2% for the medial tibio-femoral compartment. The re-rupture rate was 1.2% and the further surgical revision rate was 5.4%. Conclusion Anterior laxity at last follow-up was consistent with previous studies of revision ACL reconstruction. However, rotational stability and the re-rupture risk were improved. ALL stabilisation is among the techniques that deserve consideration as part of the therapeutic options for revision ACL reconstruction. Level of evidence IV, retrospective and prospective cohort study.

Resume Introduction Dans l’arthroplastie totale de genou, la chirurgie assistee par ordinateur se definit depuis plus de 10 ans comme l’outil de precision pour aligner les implants dans le plan frontal. Notre hypothese a ete qu’une imprecision sur les reperes squelettiques pendant la phase d’acquisition et/ou une variabilite de mesure du systeme optique infrarouge pouvaient remettre en question la pertinence des informations numeriques qui guident le geste operatoire. Materiel et methode Une modelisation geometrique d’un systeme de navigation, sans acquisition d’imagerie preoperatoire, a permis de simuler les etapes du processus d’acquisition. Le centre de chaque reflecteur optique et les points anatomiques d’acquisition ont ete bruites aleatoirement de maniere multidirectionnelle dans une sphere d’incertitude dont le diametre a ete prealablement fixe. Trente mille simulations realisees selon la methode statistique de Monte-Carlo ont permis a partir du modele geometrique virtuel et du processus de navigation de calculer la variabilite des referentiels anatomiques qui guident les coupes osseuses. Les variabilites en rotation (α, β et γ) des reperes squelettiques femoral et tibial ont traduit respectivement les erreurs de positionnement des implants en flexion–extension, valgus–varus et rotation. Resultats En considerant les incertitudes du systeme de mesure optique infrarouge 3D et de l’acquisition des points anatomiques, les reperes femoral et tibial ont montre une erreur maximale alpha (flexion–extension), beta (valgus–varus) et gamma (rotation axiale) respectivement de 1,65° (0,9°) ; 1,51° (0,98°) et 2,37° (3,84°). La variabilite du systeme de mesure optique infrarouge n’a pas eu d’influence significative sur les angles d’alignement femoro-tibiaux. Conclusion Sur la base d’une simulation de Monte-Carlo, les systemes de navigation demontrent une certaine vulnerabilite pour le guidage en rotation mais une robustesse pour le controle de l’alignement frontal et coronal. Niveau de preuve de l’etude IV.

Resume Les recidives d’entorse apres ligamentoplastie du ligament croise anterieur (LCA) posent le difficile probleme de leur diagnostic etiologique. Les genoux dont le LCA a ete reconstruit presentent frequemment une laxite anterieure residuelle ou controlent parfois insuffisamment la stabilite rotatoire. L’examen ligamentaire des genoux sain et lese juste avant le nouveau traumatisme constitue une double reference a laquelle doit se referer le praticien pour definir les differentes entites anatomocliniques. Le seuil de la laxite anterieure comparative attestant l’incompetence du transplant se situe a 5 mm selon les criteres du groupe examen ligamentaire de la fiche IKDC. Une re-rupture traumatique se differencie en fonction du contexte clinique, d’un echec anatomique precoce ou d’une distension progressive. Un transplant continu et percu en hyposignal a l’IRM doit etre confronte a l’examen clinique, aux mesures instrumentales (KT 1000™) et radiographiques de la laxite avant d’affirmer son integrite. Le macrotraumatisme n’est que revelateur de l’echec en cas d’erreurs techniques liees a un mauvais positionnement des tunnels osseux. Les hypersignaux intra-osseux ou meniscaux persistants apres le premier traumatisme peuvent simuler une lesion recente. Certains facteurs predisposant aux recidives d’entorse ont ete analyses en tenant compte de l’experience des auteurs et des donnees recentes de la litterature.

Resume Introduction Notre etude a evalue la precision de reperes squelettiques mis en place a partir de reconstructions tridimensionnelles in vivo du membre inferieur realisees avec le systeme de radiographie biplanaire basse dose EOS®. Materiel et methodes Une base de donnees de 99 reconstructions de neuf membres inferieurs appartenant a sept patients a ete realisee par quatre operateurs. Huit reperes ont ete definis a partir de regions et points anatomiques du tibia et du femur. Pour chaque os et chaque repere etudie, un repere moyen issu de 11 series consecutives a ete calcule. L’ecart de chaque repere construit au repere moyen correspondant a ete calcule suivant les axes anteroposterieur (X), longitudinal (Y) et mediolateral (Z), en translation (Tx, Ty, Tz) et en rotation (Rx, Ry, Rz). L’incertitude a ete estimee par l’intervalle de confiance a 95 % (IC95 %). Resultats IC 95 % de Tx, Ty, Tz etait respectivement inferieur a 1 mm, 0,5 mm, 1,5 mm pour le femur et 1,5 mm, 0,6 mm, 0,6 mm pour le tibia. Les reperes femoraux utilisant le centre ou le bord posterieur des condyles posterieurs pour construire l’axe mediolateral ont ete retenus avec une incertitude pour les rotations femorales Rx, Ry, Rz, inferieure a 0,3°, 4° et 0,5°. L’ensemble des reperes tibiaux utilisant les bords posterieurs des plateaux a eu une reproductibilite comparable en rotation, 95 % des ecarts Rx, Rz etaient respectivement inferieurs a 0,5° et 1,3°. Pour la rotation tibiale Ry, l’erreur moyenne a ete plus importante (4°) avec une incertitude (IC 95 %) de 11,2°. Les angles 3D d’implantation ont ete mesures sur deux patients en utilisant les reconstructions squelettiques 3D preoperatoires et des modeles geometriques 3D des implants recales sur les pangonogrammes EOS® postoperatoires. Type d’etude : prospective. Niveau IV

Resume Pour evaluer l’evolution radiologique des arthrodeses cervicales par cage radio-transparente et plaques anterieures, nous avons revu les blesses pris en en charge entre octobre 1999 et juin 2003 pour traumatisme du rachis cervical sans lesion neurologique medullaire. Notre serie comportait 30 patients et 32 arthrodeses. Les lesions se repartissaient en : 1 tear Drop, 8 entorses graves en flexion, 4 luxations bi-articulaires, 4 entorses graves en hyperextension, 1 luxation-fracture, 7 fractures uni-articulaires, 4 fractures-separations du massif articulaire, 3 hernies post-traumatiques. Nous avons pris en compte l’angle inter-somatique, le deplacement anterieur ainsi que la hauteur au milieu du disque intervertebral. La technique chirurgicale consistait en une arthrodese intersomatique utilisant une cage remplie d’os spongieux associee a une plaque anterieure. Il a ete associe 4 temps posterieurs. Tous les malades ont etes revus au moins jusqu’a fusion intersomatique survenue en moyenne au 78e jour. L’angle intersomatique moyen est passe de 11,6° de cyphose a 13° de lordose. Le deplacement anterieur est passe de 3 mm a 0,3 mm. La hauteur de l’espace intersomatique est passee de 5,3 a 8,2 mm. Il n’a pas ete observe de deplacement secondaire, ni de complications. Cette etude montre que l’arthrodese par cages associees a une osteosynthese anterieure peut etre utilisee en traumatologie. Cette technique d’arthrodese inter-somatique est simple, fiable et a faible morbidite pour les lesions traumatiques instables sans lesion neurologique medullaire. Elle permet une reduction quasi anatomique en un delai de fusion faible.

Background Patient-specific cutting guides were recently introduced to facilitate total knee arthroplasty (TKA). Their accuracy in achieving optimal implant alignment remains controversial. The objective of this study was to evaluate postoperative radiographic outcomes of 50 TKA procedures with special attention to posterior tibial slope (PTS), which is difficult to control intraoperatively. We hypothesized that patient-specific cutting guides failed to consistently produce the planned PTS. Material and methods The Signature™ patient-specific cutting guides (Biomet) developed from magnetic resonance imaging data were used in a prospective case-series of 50 TKAs. The target PTS was 2°. Standardised digitised radiographs were obtained postoperatively and evaluated by an independent reader. Reproducibility of the radiographic measurements was assessed on 20 cases. The posterior cortical line of the proximal tibia was chosen as the reference for PTS measurement. Inaccuracy was defined as an at least 2° difference in either direction compared to the target. Results The implant PTS was within 2° of the target in 72% of knees. In the remaining 28%, PTS was either excessive ( n = 10; maximum, 9°) or reversed ( n = 4; maximum, –6°). The postoperative hip-knee-ankle angle was 0° ± 3° in 88% of knees, and the greatest deviation was 9° of varus. Conclusion These findings support our hypothesis that patient-specific instrumentation decreases PTS accuracy. They are consistent with recently published data. In contrast, patient-specific instrumentation provided accurate alignment in the coronal plane. Level of evidence IV, cohort study.

Resume Les auteurs ont evalue au recul moyen de 5,2 ans une serie continue de 50 patients sportifs en pivots repares dans les 8 premiers jours d’une rupture isolee du LCA selon la technique de MacIntosh modifiee utilisant le tractus iliotibial. La section de la cloison intermusculaire laterale a permis une reconstitution du hauban lateral tout en prelevant une bandelette de 40 a 45 mm de largeur. Les resultats globaux selon la fiche de cotation IKDC ont ete comparables a ceux d’autres auto-transplants : 38 % (IKDC A), 46 % (B), 12 % (C), 4 % (D). La laxite residuelle differentielle moyenne a ete mesuree a l’arthrometre KT-1000 a 1,86±1,74 mm. Quarante-huit pour cent des genoux ne presentaient pas de signe de Lachman. Les ressauts ont ete neutralises dans 88 % des cas. Selon les criteres de la fiche de cotation Arpege, nous avons observe 38 % de resultats excellents, 46 % de bons resultats, 12 % de resultats moyens et 4 % de mauvais resultats. Trente-trois patients sur 50 ont conserve au recul le meme niveau d’activite sportive. Un echec anatomique precoce et deux cas de ruptures iteratives traumatiques sont survenus a 25 et 38 mois de recul. Deux flexum irreductibles de plus de +5 et trois deficits en flexion superieurs a 20 ont altere les resultats fonctionnels. Une competitrice ayant pu reprendre ses activites sportives a eu une mobilisation de son genou sous anesthesie generale. Un seul cas de hernie musculaire par dehiscence a ete observe au niveau de la zone prelevee. Le deficit residuel moyen quadricipital a ete a 12 mois de 10 % a 90/s et celui des ischio-jambiers de 1,3 % a la meme vitesse.

Inaugural cutaneous metastasis is exceptional in osteosarcoma. We report a case of a woman with osteosarcoma of the right knee who presented two tumefactions of the scalp at the time of diagnosis. Magnetic resonance imaging identified a high intensity T2 signal in the femur and also a high-intensity signal in the soft tissues. The head scan confirmed the presence of two subcutaneous tumors. Biopsy of the two sites demonstrated the metastatic nature of the cutaneous lesions. The patient was given preoperative and postoperative chemotherapy. Wide resection followed by prosthesis reconstruction was performed. Pulmonary metastases developed and led to two thoracotomy procedures. The patient has remained in remission 22 months. Six cases of cutaneous metastases of osteosarcoma have been reported in the literature. The cutaneous metastases were secondary in five of six cases, occurring after other metastatic localizations had been discovered. The present case is the first published observation of synchronous cutaneous metastases. The duration of remission suggests that cutaneous localizations should be treated like other inaugural metastatic localizations with intensive chemotherapy and wide resection of the primary tumor.

The purpose of this study was to test the hypothesis that the surgical technique using alternating fluid irrigation and carbon dioxide (CO2) gas medium as a means of knee joint distension during arthroscopy is a safe and effective method, compared to traditional fluid arthroscopy. This prospective randomized comparative study involved 94 patients undergoing the same arthroscopic ACL reconstruction surgical procedure except for the medium used to distend the joint: In a first group of 48 patients (“ACL gas” group), CO2 insufflation was mainly used, at a low pressure of 40–50 mmHg, alternating with a fluid medium for knee joint washout only. In the second group of 46 patients, classical arthroscopic joint distension by fluid was used, with a pump pressure of 50–70 mmHg. Early pre- and post-operative complications, duration of surgery, intraoperative monitoring data and particularly the end-tidal carbon dioxide (EtCO2) as a marker of CO2 blood diffusion were prospectively collected. EtCO2 and other monitoring data changes before and after tourniquet release were not different between the two groups. Tourniquet time was significantly longer when using fluid rather than gas. We observed 3 cases of small and localized subcutaneous emphysema, resolving completely within hours. Hematoma and reflex sympathetic dystrophy occurred more often in the “ACL fluid” group, with no statistical significance. Low-pressure CO2 knee joint insufflation proved to be a safe technique capable of improving surgical comfort compared with the use of fluid alone. The CO2 blood diffusion measured by end-tidal carbon dioxide monitoring during ACL arthroscopic reconstruction was similar with or without gas insufflation. Randomized controlled trial, Level I.

Summary Introduction Lower extremity alignment remains one essential objective during total knee replacement. Implants positioning analysis requires selecting reliable skeletal landmarks. Our objective was to in vivo evaluate the precision of the implemented skeletal landmarks. This evaluation was based on multiple three-dimensional (3D) computer reconstructions of the lower extremity derived from an EOS ® biplanar low-dose X-ray system acquisition. A 3D angle measurement protocol was used. Hypothesis Currently defined landmarks carry a tolerable uncertainty margin, which can still probably be further improved. Material and methods Nine lower extremity 3D computer reconstructions were obtained from an EOS protocol based on seven simultaneous A–P and lateral views performed in standing position. A database was established by four operators; finally, building up a total of 99 in vivo 3D reconstructions of these nine lower extremities. Specific algorithms were used for such 3D reconstructions of lower extremities based on bone points and pre-identified contours on X-ray. Four femoral landmarks and four tibial landmarks were thus defined. For each bone and each landmark studied, a mean landmark for the 11 consecutive series elements was established. The deviation from each constructed landmark to the corresponding mean landmark was calculated based on the anteroposterior ( x ), longitudinal ( y ) and mediolateral axes ( z ), in translation (T x , T y , T z ) and in rotation (R x , R y , R z ). Uncertainty was estimated by the 95% confidence interval (95% CI). Results The landmarks located at the middle of the segment joining the center of each posterior condyle and at the barycenter of the plateaux showed a greater reliability; these landmarks uncertainty (95% CI) of T x , T y , T z was less than 1, 0.5, 1.5 mm for the femur and 1.5, 0.6, 0.6 mm for the tibia, respectively. The femoral landmarks using the center or posterior edge of the posterior condyles to define the mediolateral axis were retained; for rotations R x , R y , and R z , uncertainty remained less than 0.3, 4, and 0.5°. All of the tibial landmarks had a comparable reliability in rotation, 95% of the R x and R z deviations were under 0.5 and 1.3°, respectively, with a mean error less than 1°. For the tibial rotation R y , the mean error was greater (4°), with uncertainty (95% CI) at 11.2°. All tibial translations showed a mean error of 1 mm. The 3D implantation angles were measured on two patients using preoperative 3D skeletal reconstructions and 3D geometric models of the implants repositioned on postoperative EOS ® knee X-rays. Discussion The posterior condyles are rarely involved in the arthritic wear process, making them an anatomic landmark of choice in the analysis of the femoral component positioning. The femoral landmarks using the posterior condyles were sufficiently reliable for clinical use. However, the posterior contours of the tibial plateaux were less precise. The knees should be staggered from an anteroposterior perspective on the EOS ® lateral images so that they can be visualized separately. The anatomic zones on which the skeletal landmarks are based are usually removed by the bone cuts, making it preferable to save the preoperative computer reconstructions to analyze the postimplantation 3D reconstruction. Conclusion The lower extremity skeletal landmarks precision relates to the quality of the corresponding 3D reconstructions. Except for tibial rotation, all the translation and rotation parameters were estimated within a mean error margin inferior to 1.2 mm and 1.3°, respectively. Making the reconstruction algorithms more robust would render certain anatomic zones even more precise. Biplanar low-dose EOS ® X-ray system is a tool of the future to generate 3D knee X-rays that can improve the evaluation and follow-up of total knee arthroplasty patients. Level of evidence: level IV, diagnostic study.

Introduction The causes of failure of anterior cruciate ligament (ACL) reconstruction mainly involve incorrect tunnel positioning. There is no intraoperative tool allowing the surgeon to test graft biomechanics and to confirm that the new graft is in an optimal position. Hypothesis Control is improved with computer assisted navigation. Material and methods In this retrospective study, revision ACL reconstruction was performed with a new autologous graft in a continuous series of 52 failed ACL reconstructions. A computer assisted navigation system was used intraoperatively in all knees. Evaluation with this system confirmed the position of old and new tunnels as well as intraoperative laxity. Results Evaluation of tunnel position based on traditional radiological criteria found in the literature significantly underestimated graft biomechanics: 69% of the cases presented with unfavorable graft ansiometry (mean: 13 ± 2.2 mm) while the correct position of the tibial tunnel was identified in 64% of cases on radiography and the femoral tunnel in 48%. All new grafts were optimally positioned by the computer assisted navigation system with a mean isometery of 3.2 (±0.7) mm. Comparative pre- and postoperative evaluation of laxity showed a statistically significant improvement (P