Computer-assisted Anterior Cruciate Ligament(ACL) Reconstruction:The US Perspective
Jason Koh,MD*and Matthew S.Marcus,MD w
Abstract:Computer-assisted anterior cruciate ligament(ACL) reconstruction in the United States has been ud to help improve clinical outcomes and investigate tunnel placement and kinematic activity.Computer-assisted techniques were developed to improve accuracy of tunnel placement,becau of concerns about the accuracy of manual tunnel placement causing revisions.Several authors have demonstrated improved tunnel location with com-puter assistance,although others have demonstrated little or no difference.More recently,American investigators have ud com-puter assistance to evaluate the position and biomechanical behavior and kinematics of theoretical tunnel placement and also to asss in vitro and in vivo knee stability following ligament reconstruction.Computer assistance of anterior ligament recon-struction has demonstrated its value as a rearch and clinical tool in the United States.
Key Words:anterior cruciate ligament,computer assisted,navi-gation,tunnel placement,knee surgery
(Sports Med Arthrosc Rev2014;22:206–214)语音信箱
A nterior cruciate ligament(ACL)reconstruction has
五四演讲稿
become a common surgical procedure with an esti-mated200,000injuries annually in the United States,1with the majority performed by surgeons who do<1a week and over20%performed by tho doing<6a year.2Computer-assisted ACL reconstruction in the United States has been ud to help improve clinical outcomes3and investigate tunnel placement4–7and kinematic activity.4,8,9Computer-assisted techniques were developed to improve accuracy of tunnel placement,10–14becau of concerns about the accuracy of manual tunnel placement13,15–17causing revi-sions.18Several authors have demonstrated improved tunnel location with computer assistance,5,15,19although others have demonstrated little or no difference.20,21More recently,American investigators have ud computer assistance to evaluate the position6and biomechanical behavior and kinematics of theoretical tunnel place-ment22,23and also to asss in vitro and in vivo knee sta-bility following ligament reconstruction.6,24,25Computer assistance of anterior ligament reconstruction has demon-strated its value as a rearch and clinical tool in the United States.
GUIDANCE
Early U of Computer Guidance
Early computer-aided guidance techniques were ini-tially developed in the United States to assist in appropriate tunnel placement.Douglas Jackson in the early1980s devid a technique where computed tomography(CT) scanning was ud to provide guidance for tunnel posi-tions.26Intraoperatively,the knee wasfixed in a frame,and then the patient was transferred for an intraoperative CT scan.Tunnel positions were calculated and then drilled with the knee still within the frame.Although effective,this was a laborious procedure,and there was a transition to an arthroscopic technique.
Need for Accuracy of Tunnel Placement
It is well established that graft placement and tunnel position have significant clinical effects on outcomes after ACL reconstruction.Although the appropriate position for ACL grafts remains a source of ongoing debate,there are clearly tunnel positions that are nonanatomic and result in significant effects on the knee.18,27–36Tunnel placement can change graft strain,35,36impingement on adjacent structures,28,37–39and may fail to control rotational stress on the knee.36Exces-sively anterior tibial tunnel placement can result in graft impingement,loss of knee extension,knee synovitis,and graft failure,most likely becau of chronic damage to the liga-ment.27,28,40–42Posterior tibial tunnel placement can result in a vertical graft orientation and decread rotational
con-trol,39,40,43,44as well as posterior cruciate ligament impinge-ment causing loss of kneeflexion or graft strain.39Medial tibial tunnel placement has also been associated with loss of knee flexion.45Femoral tunnel placement also has significant effects on knee mechanics.Transtibial drilling can result in excessively anterior femoral tunnels,resulting in grafts that are tight in flexion and loo in extension.6,23,46A more vertically oriented graft may result in poor control of knee rotation,which is a critical part of the pivot shift phenomenon.47The complexity of graft placement is incread with the u of double tunnel techniques to create double bundle ACL reconstructions. Increasing the number of tunnels that need to be drilled pro-vides additional opportunity for misplacement and also the possibility that tunnels may inadvertently converge.48–50 Clinically,the result of inappropriate tunnel placement is poor patient outcomes.51–55The patients have wor Lysholm and IKDC scores,55incread knee laxity,56pain, and higher rates of graft failure and revision.38,47,53At mid-term follow-up(7y)the patients have higher rates of osteoarthritis of the knee.33
Surgeon Accuracy With Manual Tunnel Placement
Multiple authors have evaluated the accuracy of ACL tunnel placement,both in a laboratory and clinical tting.
From the*Department of Orthopaedic Surgery,NorthShore Uni-
versity Health System,Evanston;and w Department of Orthopaedic
Surgery,University of Chicago Pritzker School of Medicine,
Chicago,IL.
J.K.rved as a consultant to Aesculap-B.Braum regarding computer
navigation.M.S.M.has no relevant disclosures.
Disclosure:The authors declare no conflict of interest.
Reprints:Jason Koh,MD,Department of Orthopaedic Surgery,
NorthShore University Health System,2650Ridge Ave.,
Walgreen’s2505,Evanston60201,IL
Copyright r2014by Lippincott Williams&Wilkins
R EVIEW A RTICLE
206| Sports Med Arthrosc Rev Volume22,Number4,December2014
ACL reconstruction using standard techniques has a failure rate of up to20%.57The primary reason for the failures has been identified as incorrect tunnel position in up to 70%to80%of cas.18,47,58In both clinical and controlled laboratory ttings,reproducible,accurate tunnel place-ment can be difficult to consistently achieve even for experienced surgeons,with up to40%of tunnels in an undesired position.59Postoperative imaging studies have demonstrated a high degree of variability in tunnels placed by purely arthroscopic guidance.60–63This may be related to the difficulty of asssing relative depth and perspective using a monocular arthroscope and the challenge of appropriate identification of intra-articular landmarks. Additional feedback in the form of a virtual map can potentially enhance the accuracy of identification.
One of thefirst studies demonstrating the significant variability of arthroscopically placed tunnels was per-formed at the University of Pittsburg.13Two experienced ACL surgeons drilled tunnels in20identical foam knees using standard arthroscopic guides.The femoral tunnel deviated on average4.2mm±1.8mm from the ideal posi-tion,and tibial tunnel deviated 4.9±2.3mm from the desire
d location.Similarly,in another study performed on identical foam knees by4surgeons,the femoral tunnel was 2.3to4.5mm away from the desired location,and the tibial tunnel was2to3.4mm away.64
Cadaveric studies have also shown similarfindings.A group of24experienced ACL specialists performed liga-ment reconstruction at an advanced arthroscopy cour. After the procedures,specimens were discted and tunnel position evaluated.In12of24knees,the femoral tunnel was felt to be inaccurate,and6of24tibial tunnels were also deemed inappropriately located.17exceedingly
Radiographic evaluation of tunnel positioning either intraoperatively or postoperatively also has shown that even very experienced ACL surgeons will not be satisfied with purely arthroscopically placed tunnels.Several groups have shown a rate of repositioning of approximately15% when using intraoperativefluoroscopic guidance,even for experienced surgeons.61,62
Another study involved postoperative radiographic evaluation of tunnels in32patients.16The2experienced ACL surgeons,using either a mini-open or arthroscopic technique,created tunnels and recorded their presumed locations.The were correlated with location as identified radiographically.There was substantial deviation between the intraoperative and postoperative radiographicfindings. The coronal position of the tibial tunnel had poor corre-lation
(R2=0.14,P=0.22),and the anterior-posterior tunnel position on the lateral view had no correlation (R2=0.07,P=0.36).Four tunnels out of32(12.5%)“were in very different positions to that expected by the surgeon.”
Other authors such as Aglietti et al51and Howell and Clark28have found in radiographic and magnetic resonance imaging follow-up studies that a high rate of variability of tunnel position exists even among experienced knee sur-geons who specialize in ACL reconstruction.This has sig-nificant clinical implications.The multicenter MARS group reported that60%of revisions had a specific technical cau of failure,and47.6%had femoral tunnel malposi-tion.Inappropriate tunnel placement remains the most common mode of graft failure resulting in revision.65 Several authors have suggested the u of alternative arthroscopic techniques,such as placing the scope in a medial portal,to enhance visualization of intra-articular landmarks.Although we feel that this can enhance the ability to e the lateral wall of the intercondylar notch,it is unclear if this has resulted in improved surgical outcomes in a clinical tting.Although some studies by expert surgeons show improvements in outcomes with drilling the femoral tunnel through an anteromedial portal,66issues continue to occur despite the u of this technique.A recent large reg-istry study has shown a higher rate of ACL reconstruction failure and revision when the initial femoral tunnel was drilled though the a
nteromedial portal.67This may be related to unfamiliarity with arthroscopic anatomy as visualized from this portal.
Accuracy of Computer-assisted Systems
Preci3-dimensional location of the knee joint has been accomplished using both optical and electromagnetic tracking systems.The u of electromagnetic systems for ACL deficient knees has been primarily in a laboratory tting,and systems that are available for clinical u typ-ically have ud an infra-red camera system to track passive markers rigidly attached to the tibia and femur.The infra-red systems can track the position of the femur,tibia, and various instruments to within<1mm and<1 degree.11,68We have the most experience with an image-free,wireless system(Orthopilot,Aesculap-BBraun,PA) that does not require intraoperativefluoroscopy or pre-operative CT or radiographic images11(Fig.1).Dynamic, real-time information of knee position and anterior-poste-rior and rotational laxity is captured during anterior drawer,Lachman,and rotational tests.With the most recent software(V3.0),the pivot shift can be performed and the relative anteroposterior translation and rotation during the maneuver is graphically displayed.Femoral and tibial tunnel positions and angles are identified with respect to intra-articular landmarks.
brainy
TECHNIQUE
全天候什么意思
The image-free system is initiated after standard graft preparation and addressing the intra-articular damage of the knee,such as meniscal injuries and excess stump removal.Patient identification,laterality,and size and type of graft are input into the computer.The order of tunnel drilling is also lected.Two2.5mm K-wires are ud to curely attach rigid bodies with passive reflective markers to the femur and to the tibia(Fig.2).The markers are in unique configurations that can be recognized by the navi-gation system.Another unique rigid body is attached to the instrumentation.
Registration of extra-articular landmarks is then per-formed,using a special pointer and a foot pedal to indicate that the correct position has been achieved.The land-marks are the medial and lateral sides of the tibial plateau, tibial tubercle,and anterior tibial crest.Static extension and 90degrees offlexion are measured,followed by registration through a dynamic range of motion.
Laxity testing is then performed at chon degrees of flexion.Both anterior-posterior translation and rotation are displayed and recorded.Pivot shift testing is also performed and the resulting curve of translation and rotation com-pared with degrees offlexion can be analyzed.
As typical with arthroscopic-assisted ACL recon-struction,intra-articular landmarks are visualized;how-ever,they are also registered in the navigation system using
Sports Med Arthrosc Rev Volume22,Number4,December2014Computer-assisted ACL Reconstruction r2014Lippincott Williams&Wilkins 207
a pointer with attached rigid body.The landmarks on the tibial side include the posterior cruciate ligament,anterior horn of the lateral meniscus,and medial tibial eminence,along with the tibial footprint of the ACL.On the femoral side,notch width and shape (Fig.3)are registered.The femoral ACL footprint,articular cartilage edge,and over the top position are recorded.The registered length of Blumensaat’s line can be compared with known standards or premeasured radiographic values.This is an additional accuracy check that can reduce the risk of mistaking “resident’s ridge”as the “over the top”position.
Tunnel positions can then be independently chon using pointers or guides with attached markers.The quence of tunnel drilling can be chon according to surgeon preference,as can be the number of tunnels drilled.Figure 4depicts the femoral tunnel navigation for a
宝贝的英文怎么写posterolateral bundle.The location of the tunnel with respect to the previously drilled anteromedial bundle loca-tion and within the native footprint is identified.The dis-tance from the over the top position and percentage loca-tion in the anterior-posterior plane are shown.The relative clock-face orientation and the amount of impingement are also calculated and displayed.
Tibial tunnel guidance also shows the relationship of the various tunnels,their angulation,the amount of graft isometry,and the location of the tunnels with respect to the intercondylar notch and the original footprint,as well as to the posterior cruciate ligament (Fig.5).Esntially,the navigation screens provide a map for tunnel position,as well as an indicator of the mechanical conquences of the position.
Laxity measurements are then repeated after appro-priate graft passage and fixation.Pre-operative and post-operative anterior-posterior translation and rotation are shown (Fig.6),and the pivot shift curves can also be obtained and compared with baline (Fig.7).
Time needed for the navigation portion of the proce-dure is minimal,consisting of 3to 5minutes to fix the K-wires and register the landmarks.Another 5to 7minutes are ud for enhanced decision making as it becomes readily apparent that there will need to be tradeoffs for the different tunnel positions.Of note,the “normal”anatomy can
often
FIGURE 1.Orthopilot system,showing computer,monitor screen,and infrared camera head
(arrow).
FIGURE 2.Intraoperative registration.Note passive markers (arrows)on tibia,femur,and
华中农业大学分数线
instrumentation.
FIGURE 3.Screen graphic of intra-articular registration of inter-condylar notch dimensions.
Koh and Marcus Sports Med Arthrosc Rev
Volume 22,Number 4,December 2014
208|
r
2014Lippincott Williams &Wilkins
result in graft impingement or anisometry,suggesting that the may be contributing significantly to the underlying caus of ACL rupture.
Other Systems
Several other systems have been developed,but at the time of this article,do not appear to be commercially sup-ported.They are discusd here briefly as different
investigators have utilized them in clinical or rearch ttings.Their primary clinical usage has been outside of the United States,although rearchers have ud them to investigate tunnel positions and biomechanics in the United States.
Brainlab
Brainlab (Mu nchen,Germany)VectorVision ACL 1.0utilizes a standalone computer with infrared
control.
FIGURE 4.Double bundle femoral navigation.Note that information is provided regarding femoral tunnels with regard to tunnel position on intercondylar notch wall,clock face,impingement,and tunnel interction.Navigation screen provides labels on graphics to aid in tunnel
positioning.
FIGURE 5.Double bundle tibial navigation.Navigation screen showing tunnel positions with regard to intercondylar notch projection in extension,relative tunnel location,and isometry.
Sports Med Arthrosc Rev
Volume 22,Number 4,December 2014Computer-assisted ACL Reconstruction
r
2014Lippincott Williams &Wilkins |
209
Passive infrared reflectors are fixed to the femur and tibia.At the beginning of the ACL reconstruction,true ante-roposterior and lateral radiographs are made of the femur and tibia with a calibrated c-arm that is connected to the computer-assisted surgery navigation system.The are ud to help with templating the tunnel positions.
This system has been ud clinically in Europe,notably by Meuffels and colleagues in a prospective study where tunnels were evaluated with CT scans.Surprisingly,“there
was a considerable and unexpected lack of precision in tibial and femoral tunnel placement in both groups (navi-gated and un-navigated).”This lack of precision is con-cerning and rais a question of if this result was related to the specific system ud or other aspects of the technique.21
男生去痘Praxim
Praxim (Grenoble,France)utilizes a standalone computer with infrared reflectors.There is no
remembermeadditional
picturesFIGURE 6.Double bundle preoperative and postoperative rotational and translational stability at 29degrees knee flexion.Preoperative and postoperative anterior translation and internal and external rotation are
shown.
FIGURE 7.Double bundle pivot shift rotational and translational stability.The relative anteroposterior translation and rotation of the tibia and femur are shown with respect to knee flexion during a pivot shift test preoperatively and postoperatively.
Koh and Marcus Sports Med Arthrosc Rev
Volume 22,Number 4,December 2014
210|
r
2014Lippincott Williams &Wilkins
