A new technique in double-bundle anterior cruciate ligament reconstruction with implant-free tibial fixation.

PURPOSE: This case-series outcome study presents a surgical technique for anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with 4-tunnel using two interference screws. There was a 2-year minimum follow-up. METHODS: From January to December 2009, an ACL 4-tunnel, anatomic, double-bundle reconstruction was performed on 27 patients. Double-strand hamstring tendon grafts were used in each femoral tunnel as well as two interference screws. Tibial fixation was insured through manual tension, by tying non-absorbable sutures on the bone bridge between the two tunnels at 20° of knee flexion. Clinical assessments included the International Knee Documentation Committee (IKDC) and Lysholm knee scores, range of motion (ROM), pivot-shift test, single-leg hop, and quadriceps-hamstrings strength tests using a hand-held dynamometer. Anterior knee laxity was also assessed using a rolimeter. A single examiner performed all testing pre-operatively at 6 months and during the 2-year follow-up. RESULTS: All patients were assessed during the 2-year follow-up. At that time, 92 % of the patients presented normal anterior laxity (average, 1.3 ± 0.5 mm) and rotational knee stability. No statistical side-to-side difference was found for ROM, muscle strength, single-leg hop, and function (n.s.). All patients presented a normal knee function according to the IKDC and the Lysholm score. In addition, no infection, graft failure, or pain were observed at the harvesting site. CONCLUSION: The study shows that satisfactory results in relation to knee laxity, function, and strength can be achieved with the implant-free tibial fixation in the ACL double-bundle reconstruction with two interference screws. LEVEL OF EVIDENCE: Therapeutic case series, Level IV.

Effect of fatigue on tibial rotation after single- and double-bundle anterior cruciate ligament reconstruction: a 3-dimensional kinematic and kinetic matched-group analysis.

BACKGROUND: Fatigue is an extrinsic factor adversely affecting joint proprioception and neuromuscular response, thereby increasing anterior cruciate ligament (ACL) strain and injury risk. The effectiveness of the single- and double-bundle techniques for ACL reconstruction to control residual rotational knee laxity under fatigue has not been examined. HYPOTHESIS: Fatigue results in a significant increase in tibial rotation angles and moments in both ACL-intact and single- and double-bundle ACL-reconstructed knees. The 2 groups with ACL-reconstructed knees will show no significant differences in tibial rotation angles and moments either pre- or postfatigue. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-four male patients who underwent successful single-bundle (n = 12) or double-bundle (n = 12) ACL reconstructions and 10 matched healthy controls were subjected to a standard lower limb muscle fatigue protocol using an isokinetic dynamometer. Three-dimensional motion analysis was used to measure tibial rotation and rotational knee moments in the pre- and postfatigue states, during a swinging maneuver on the weightbearing leg from a standing position with the knee in extension. RESULTS: Tibial rotation of the single-bundle group significantly increased postfatigue (prefatigue 22° ± 10° vs 29° ± 15° postfatigue, P = .015). In contrast, the double-bundle group showed similar tibial rotation values pre- and postfatigue (16° ± 6° vs 18° ± 4°, P = .22). The double-bundle group showed a trend toward decreased tibial rotation values pre- and post-fatigue compared with controls (22 ± 4 and 23 ± 4) (P = .065 and .08, respectively). In the prefatigue state, rotational moments (N·mm/Kg) of the single-bundle (339 ± 148) and double-bundle (317 ± 97) groups were significantly lower than that of controls (465 ± 134) (P = .05 and .03, respectively). In the postfatigue state, an increase was observed in rotational moments of the single-bundle (388 ± 131) and double-bundle (408 ± 187) groups compared with prefatigue values, whereas a decrease was noted in the control group (411 ± 117). CONCLUSION: Single-bundle ACL-reconstructed knees demonstrate a reduced ability to resist rotational loads under fatigue. Double-bundle reconstructed knees had significantly better control of tibial rotation when fatigued. However, they demonstrate an excessive, yet not significant, reduction in tibial rotation compared with the intact knee, suggesting a possible overcorrection in rotational laxity.

Postoperative evaluation of tibial footprint and tunnels characteristics after anatomic double-bundle anterior cruciate ligament reconstruction with anatomic aimers.

Following anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with hamstring tendon autografts, 38 consecutive patients were evaluated with high-speed three-dimensional computed tomography. Scans were performed within 3 days following surgery. The length and width of the reconstructed ACL footprint were measured on axial images. Then, 3D images were converted into 2D with radiologic density for measurement purposes. Tunnel orientation was measured on AP and lateral views. In the sagittal plane, the center of the anteromedial (AMB) and posterolateral bundle (PLB) tibial attachment positions was calculated as the ratio between the geometric insertion sites with respect to the sagittal diameter of the tibia. In addition, the length from the anterior tibial plateau to the retro-eminence ridge was measured; the relationship of this line with the centers of the AM and PL tunnels was then measured. The AP length of the reconstructed footprint was 17.1 mm ± 1.9 mm and the width 7.3 mm ± 1.2 m. The distance from retro-eminence ridge to center of AM tunnel was 18.8 mm ± 2.8 mm, and the distance from RER to center of PL tunnel was 8.7 mm ± 2.6 mm. The distance between tunnels center was 10.1 mm ± 1.7 mm. There were no significant differences between the intra- and inter-observer measurements. The bone bridge thickness was 2.1 mm ± 0.8 mm. In the sagittal plane, the centers of the tunnel apertures were located at 35.7% ± 6.7% and 53.7% ± 6.8% of the tibia diameter for the AMB and PLB, respectively. The surface areas of the tunnel apertures were 46.3 mm(2) ± 4.4 mm(2) and 36.3 mm(2) ± 4.0 mm(2) for the AM and PL tunnels, respectively. The total surface area occupied by both tunnels was 82.6 mm(2) ± 7.0 mm(2). In the coronal plane, tunnel orientation showed the AM tunnel was more vertical than the PL tunnel with a 10° divergence (14.8° vs. 24.1°). In the sagittal plane, both tunnels were almost parallel (29.9° and 25.4° for the AM and PL tunnels, respectively). When using anatomic aimers, the morphometric parameters of the reconstructed tibial footprint in terms of length and distances to the surrounding bony landmarks were similar to the native ACL tibial footprint. However, the native footprint width was not restored, and the surface area of the two tunnel apertures was in the lower range of the published values for the native footprint area.

Evaluation of the bone bridge between the bone tunnels after anatomic double-bundle anterior cruciate ligament reconstruction: a multidetector computed tomography study.

BACKGROUND: Double-bundle anterior cruciate ligament (ACL) reconstruction is a technically demanding procedure; it requires drilling 2 tibial and 2 femoral tunnels. Tunnel communication, whether intraoperative or postoperative, is a serious complication: It jeopardizes knee stability and graft function. HYPOTHESIS: During double-bundle ACL reconstruction, special aimers would be helpful to avoid intraoperative bone bridge fracture. The bone bridge between the bone tunnels would maintain its structural integrity, and no tunnel communication would be observed postoperatively because of tunnel widening. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This prospective study included 32 patients undergoing double-bundle ACL reconstruction. A multidetector computed tomography study was performed at a mean of 17 months postoperatively. The thickness of the bone bridge between the bone tunnels was measured in the femoral and tibial sides on an axial and sagittal plane, respectively, at 3 locations: the level of the joint line, the midportion of the bone bridge, and the base of the bone bridge. The bone density of the bone bridge was measured in Hounsfield units in the same locations. Bone density of the anterior tibial cortex and lateral femoral condyle was measured for comparisons. RESULTS: Tunnel communication occurred intraoperatively in 1 patient on the tibial side at the level of the joint line. In the rest of the patients, a well-defined triangular bone bridge was present between the 2 tunnels in the femoral and tibial sides. The thickness at the apex of the bone bridge was 2.0 and 2.2 mm for the femur and tibia, respectively. In addition, the density of the bone bridge at its apex was similar to that of cortical bone. CONCLUSION: This study demonstrated that double-bundle ACL reconstruction, as used with anatomic aimers, produces a low rate of tunnel convergence. The bone bridge remains intact postoperatively, although it is thin at the level of the joint line.

Effect of knee flexion angle on length and orientation of posterolateral femoral tunnel drilled through anteromedial portal during anatomic double-bundle anterior cruciate ligament reconstruction.

PURPOSE: Our purpose was to evaluate the radiologic orientation and length of the posterolateral (PL) femoral tunnel when drilled through the anteromedial (AM) portal at 90 degrees, 110 degrees, and 130 degrees of flexion. METHODS: In 9 fresh cadaveric knees the anterior cruciate ligament was excised and 2.4-mm guidewires were drilled through the center of the PL bundle footprint through an accessory AM portal. Pins were advanced, in a retrograde manner, until flush with the notch wall and left in place. Outcomes were measured by use of plain anteroposterior, lateral, and tunnel radiographs to determine tunnel orientation and clock position, and direct measurement was performed to determine the intraosseous length, the shortest distance to the posterior bone cortex, and the distance to the lateral collateral ligament attachment on the lateral aspect of the femoral condyle. RESULTS: With regard to tunnel orientation, each increase in knee flexion angle resulted in a more horizontal tunnel on both the lateral and anteroposterior views. On the tunnel view, the PL guidewire became more vertical with knee flexion. The mean clock position was 9 o'clock (standard deviation [SD], 00:12). No significant difference in the intraosseous length of the guidewires was observed. According to our hypothesis, knee flexion influenced the PL tunnel characteristics. At 90 degrees of flexion, the guidewire may blow out the posterior cortex of the lateral femoral condyle. CONCLUSIONS: A PL femoral tunnel drilled through the AM portal becomes more horizontal with bending of the knee during drilling. At 90 degrees, the tunnel is at risk of back wall blowout.

Validation of the position of the femoral tunnels in anatomic double-bundle ACL reconstruction with 3-D CT scan.

This study compares the positioning of femoral AM and PL tunnels obtained with specific ancillary instruments during anatomic double-bundle ACL reconstruction with the native ACL footprint using three-dimensional computed tomography (3-D CT). In 35 consecutive patients, anatomic double-bundle ACL reconstruction was performed with specific ancillary instruments. Three-dimensional CT reconstruction of both knees was performed using the volume rendering technique. In the controls (contralateral knee, with intact ACL), the angle between the longitudinal axis of the footprint and the axis of the femur, the "footprint angle" (FA) was measured. On the involved side, using the axis passing through the tunnel centers, FA was also measured. In both the groups, footprint's length and width, and distances to cartilage margins were measured. FA was 28.1 degrees +/- 5.0 degrees in the controls and 32.9 degrees +/- 15.8 degrees on the involved side (n.s.). There was no statistical difference between the two groups for the other morphometric parameters: footprint's length and width, and distances to cartilage margins. Using specific ancillary instruments the morphometric parameters of the reconstructed femoral ACL footprint were similar to the native ACL.

Graft selection for anterior cruciate ligament reconstruction.

More than 100,000 anterior cruciate ligament reconstructions are done in the United States each year. With improvements in technology and surgical ability, the number of variables that must be considered has increased dramatically. The choice of autograft or allograft, which is one of the most important variables, has largely become a decision to be made by the surgeon and the patient. It is critical to understand the advantages and disadvantages of each type of graft to make informed and intelligent decisions.

Anatomic double-bundle anterior cruciate ligament reconstruction with anatomic aimers.

Graft positioning is a key issue in anterior cruciate ligament (ACL) reconstruction and even more sensitive in double-bundle reconstruction, where 2 tunnels have to be drilled within the ACL footprints at both the femoral and tibial insertion sites. Specific ancillary instruments have been developed to facilitate the positioning of the 4 sockets necessary when performing anatomic double-bundle ACL reconstruction. This technical note describes the rationale and the step-by-step method of using the specific aimers developed for this purpose. However, a prerequisite for successful double-bundle ACL reconstruction is a good knowledge of ACL footprint anatomy.

Influence of knee flexion angle on femoral tunnel characteristics when drilled through the anteromedial portal during anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to determine the influence of knee flexion angle for drilling the femoral tunnel during anterior cruciate ligament (ACL) reconstruction via the anteromedial (AM) portal on resulting tunnel orientation and length. METHODS: In 8 fresh cadaveric knees, the ACL was excised and 2.4-mm guidewires were drilled through the AM bundle footprint using a 5-mm endofemoral aimer via the AM portal. We compared knee flexion angles of 90 degrees , 110 degrees , 130 degrees , and maximum flexion. Anteroposterior-, lateral-, and tunnel-view radiographs were measured to determine tunnel orientation, o'clock position, and direct measurement to determine intra-osseous tunnel length. RESULTS: With regard to tunnel orientation, each increase in knee flexion angle resulted in significantly more horizontal tunnel both on the anteroposterior view and on the lateral view. While on the tunnel view, the pin became more vertical with knee flexion. At 90 degrees , tunnel length was significantly less (27 +/- 9 mm) than at greater angles, and the guidewires were either resting against the posterior cortex or breaching it. CONCLUSIONS: The results of this study show the knee flexion angle influences the position of the femoral drilling. It appears in the current study that 110 degrees is optimum, while the 90 degrees pin leads to short tunnel and is so close to the posterior wall there are high risks of posterior wall blow out when drilling the tunnel at its final diameter. Also, 130 degrees of knee flexion is responsible for high tunnel acuity and, finally, maximum flexion being quite variable from one specimen to another cannot be recommended. CLINICAL RELEVANCE: Tunnels drilled through the AM portal at 90 degrees are at risk of back wall blow out.

Using navigation to measure rotation kinematics during ACL reconstruction.

Rotational kinematics of the knee is not fully restored after single-bundle anterior cruciate ligament (ACL) reconstruction. Cadaveric experiments using knee testing machines have suggested anatomical reconstruction replacing the anteromedial and posterolateral bundles could restore knee kinematics more effectively than single-bundle reconstruction. However, practical tools to objectively assess knee rotational laxities clinically have not been available. We used an optically based computer-assisted navigation system to measure the tibiofemoral motion kinematics in four fresh whole cadavers. Standard clinical knee laxity tests (anterior drawer, Lachman, and pivot shift) were performed and the kinematics described in terms of tibial axial rotation and anteroposterior translation. Data were obtained for intact knees after excision of the ACL and sequential reconstruction of the anteromedial and posterolateral bundles. In the ACL-deficient knee, the mean maximum tibial rotation during the pivot shift test was 27 degrees and mean maximum translation 11 mm. Reconstruction of the anteromedial bundle reduced the rotational component to 18 degrees and translation to 7 mm. Reconstruction of the posterolateral bundle reduced rotation to 14 degrees . This pilot study suggests computer assisted navigation could provide a practical method to objectively measure the pivot shift and may be used clinically to demonstrate differences in the control of tibiofemoral rotation kinematics afforded by single and two-bundle ACL reconstructions.

Morphology of anterior cruciate ligament attachments for anatomic reconstruction: a cadaveric dissection and radiographic study.

PURPOSE: To define the positions of the attachments of the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL). METHODS: The shape and positions of the femoral and tibial attachments of the 2 bundles relative to bony landmarks were measured in 7 fresh-frozen, unpaired cadaveric knees by 6 independent observers. Metallic marker beads were then inserted into the defined anatomic points, and plain radiographs of the specimens were taken. We used the line described by Amis and Jakob on the tibia and the grid prepared by Bernard et al. for the femur to define AM and PL bundle attachment positions. RESULTS: In the cadaveric specimens, referencing the position of the AM bundle tibial attachment from the retro-eminence ridge (RER) resulted in the least interobserver error. On tibial radiographs, the distance between the posterior tibial cortex and the perpendicular projection of the center of the AM bundle attachment onto Amis and Jakob's line was 35.6 +/- 5.1 mm. The ratio of this distance to the length of Amis and Jakob's line (from the anterior cortex) was 36% +/- 3.8% (and 52% +/- 3.4% for the center of the PL bundle). On the femur, the center of the AM bundle was situated at 26.4% +/- 2.6%, and the center of the PL bundle at 32.3% +/- 3.9%, along the length of Blumensaat's line. CONCLUSIONS: The RER provides an easily identifiable and accurate reference point that can be used clinically. On a lateral radiograph, the positions of the tibial attachments can be referenced to Amis and Jakob's line. This method, different from Blumensaat's line, is independent of knee flexion. CLINICAL RELEVANCE: This study details anatomically and radiologically the positions of the attachments of the AM and PL bundles of the ACL. This could assist with accurate tunnel placement in reconstruction surgery and provide reference data for postoperative radiographic evaluation.

Evaluation of posterior cruciate ligament healing: a study using magnetic resonance imaging and stress radiography.

PURPOSE: To review a series of tears of the posterior cruciate ligament (PCL) in order to understand its healing process, as well as to identify prognostic factors. TYPE OF STUDY: Prospective study. METHODS: Eighteen patients with isolated or combined PCL tears were evaluated and followed-up for 1 year after their initial injury. Magnetic resonance imaging (MRI) scans and stress radiographs were obtained serially at the time of injury, at 6 months, and at 12 months. RESULTS: Twelve of 18 PCL tears were found to have regained continuity at the 1-year follow-up. These patients complained of an isolated or combined PCL/medial collateral ligament injury at time 0 and all presented a posterior subluxation of less than 8 mm, detected with stress radiographs. The remaining 6 patients had posterior subluxations greater than 12 mm and presented with combined posterolateral corner injuries. CONCLUSIONS: This study underlines the importance of a complete MRI evaluation used in combination with stress radiography to adequately assess the healing process. The results obtained suggest that complete PCL tears with greater than 12 mm of posterior subluxation, as well as combined PLC injuries, are less likely to heal completely. These factors could further aid the surgeon in deciding the need and timing for surgical intervention in the acute setting of a PCL tear. LEVEL OF EVIDENCE: Level II.

Double-stranded hamstring graft for anterior cruciate ligament reconstruction.

Current techniques for anterior cruciate ligament (ACL) reconstruction do not completely reproduce the anatomy and function of the ACL. They address only the anteromedial bundle and do not fully restore ACL function throughout the range of motion. Current grafts control anterior tibial subluxation near extension, but are less efficacious in providing rotatory stability. Recently, several authors have suggested reconstructing not just the anteromedial bundle but also the posterolateral bundle. This technical note describes a double-bundle ACL reconstruction using hamstring tendons routed through 2 tibial and 2 femoral independent tunnels.

Basic principles for surgical reconstruction of the PCL in chronic posterior knee instability.

This article describes the various options which are available for posterior cruciate ligament (PCL) reconstruction in a chronic situation. On the femoral side, one- or two-bundle grafts may be used. In laboratory conditions, 2-bundle reconstruction makes it possible to mimic more closely the biomechanics of the native PCL. However, until now there is no clear-cut clinical evidence that 2-bundle reconstruction leads to a better outcome than the 1-bundle one. On the tibial side, either a tunnel or an inlay technique can be used. The advantages and drawbacks of both techniques are still subject to debate. The results of the laboratory tests are currently in favour of the inlay fixation; however, again, the clinical issue remains to be established. In any case, proper PCL graft positioning is the key issue for a successful reconstruction. Finally, in combined posterior and postero-lateral instabilities it is necessary to correct all the components of the instability and to perform a high tibial valgus osteotomy in the case of varus alignment.