Factors affecting isometry of endoscopic anterior cruciate ligament reconstruction: the effect of guide offset and rotation

Evaluation of Tibial Tunnel Location with the Femoral Tunnel Created Behind the Resident's Ridge in Transtibial Anterior Cruciate Ligament Reconstruction

Few studies have determined whether a femoral bone tunnel could be created behind the resident's ridge by using a transtibial (TT) technique-single bundle (SB)-anterior cruciate ligament (ACL) reconstruction. The aim of this study was to clarify (1) whether it is possible to create a femoral bone tunnel behind the resident's ridge by using the TT technique with SB ACL reconstruction, (2) to define the mean tibial and femoral tunnel angles during anatomic SB ACL reconstruction, and (3) to clarify the tibial tunnel inlet location when the femoral tunnel is created behind resident's ridge. Arthroscopic TT-SB ACL reconstruction was performed on 36 patients with ACL injuries. The point where 2.4-mm guide pin was inserted was confirmed, via anteromedial portal, to consider a location behind the resident's ridge. Then, an 8-mm diameter femoral tunnel with a 4.5-mm socket was created. Tunnel positions were evaluated by using three-dimensional computed tomography (3D-CT) 1 week postoperatively. Quadrant method and the resident's ridge on 3D-CT were evaluated to determine whether femoral tunnel position was anatomical. Radiological evaluations of tunnel positions yielded mean ( ±  standard deviation) X- and Y-axis values for the tunnel centers: femoral tunnel, 25.2% ± 5.1% and 41.6% ± 10.2%; tibial tunnel, 49.2% ± 3.5%, and 31.5% ± 7.7%. The bone tunnels were anatomically positioned in all cases. The femoral tunnel angle relative to femoral axis was 29.4 ± 5.5 degrees in the coronal view and 43.5 ± 8.0 degrees in the sagittal view. The tibial tunnel angle relative to tibial axis was 25.5 ± 5.3 degrees in the coronal view and 52.3 ± 4.6 degrees in the sagittal view. The created tibial bone tunnel inlet had an average distance of 13.4 ± 2.7 mm from the medial tibial joint line and 9.7 ± 1.7 mm medial from the axis of the tibia. Femoral bone tunnel could be created behind the resident's ridge with TT-SB ACL reconstruction. The tibial bone tunnel inlet averaged 13.4 mm from the medial tibial joint line and 9.7 mm medial from the tibia axis.

Remnant Tissue Preserved Transtibial Anterior Cruciate Ligament Reconstruction With Femoral Tunnel Created Behind the Resident's Ridge

Although the transtibial (TT) technique for single-bundle (SB) arthroscopic anterior cruciate ligament (ACL) reconstruction has been widely used, surgeons often disadvantageously create the femoral bone tunnel at the arthroscopically noon position, which is alleged the "ACL isometric point," when the femoral bone tunnel could be created behind the resident's ridge with TT-SB ACL reconstruction by paying attention to the location of the tibial tunnel inlet and the angle of tibial tunnel. This alternative approach preserves ACL remnant tissue, which might contribute to better postoperative remodeling and regeneration of proprioceptive mechanoreceptors. This technique reduces surgical invasiveness and can enhance postoperative graft remodeling and proprioceptive recovery. To successfully use the devices required for this procedure, surgeons must understand the proper techniques. Hence, this technical note aims to demonstrate TT-SB ACL reconstruction with remnant tissue preservation.

Physiologic Preoperative Knee Hyperextension Is a Predictor of Failure in an Anterior Cruciate Ligament Revision Cohort: A Report From the MARS Group

BACKGROUND

The occurrence of physiologic knee hyperextension (HE) in the revision anterior cruciate ligament reconstruction (ACLR) population and its effect on outcomes have yet to be reported. Hypothesis/Purpose: The prevalence of knee HE in revision ACLR and its effect on 2-year outcome were studied with the hypothesis that preoperative physiologic knee HE ≥5° is a risk factor for anterior cruciate ligament (ACL) graft rupture.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients undergoing revision ACLR were identified and prospectively enrolled between 2006 and 2011. Study inclusion criteria were patients undergoing single-bundle graft reconstructions. Patients were followed up at 2 years and asked to complete an identical set of outcome instruments (International Knee Documentation Committee, Knee injury and Osteoarthritis Outcome Score, WOMAC, and Marx Activity Rating Scale) as well as provide information regarding revision ACL graft failure. A regression model with graft failure as the dependent variable included age, sex, graft type at the time of the revision ACL surgery, and physiologic preoperative passive HE ≥5° (yes/no) to assess these as potential risk factors for clinical outcomes 2 years after revision ACLR.

RESULTS

Analyses included 1145 patients, for whom 2-year follow-up was attained for 91%. The median age was 26 years, with age being a continuous variable. Those below the median were grouped as "younger" and those above as "older" (age: interquartile range = 20, 35 years), and 42% of patients were female. There were 50% autografts, 48% allografts, and 2% that had a combination of autograft plus allograft. Passive knee HE ≥5° was present in 374 (33%) patients in the revision cohort, with 52% being female. Graft rupture at 2-year follow-up occurred in 34 cases in the entire cohort, of which 12 were in the HE ≥5° group (3.2% failure rate) and 22 in the non-HE group (2.9% failure rate). The median age of patients who failed was 19 years, as opposed to 26 years for those with intact grafts. Three variables in the regression model were significant predictors of graft failure: younger age (odds ratio [OR] = 3.6; 95% CI, 1.6-7.9; P = .002), use of allograft (OR = 3.3; 95% CI, 1.5-7.4; P = .003), and HE ≥5° (OR = 2.12; 95% CI, 1.1-4.7; P = .03).

CONCLUSION

This study revealed that preoperative physiologic passive knee HE ≥5° is present in one-third of patients who undergo revision ACLR. HE ≥5° was an independent significant predictor of graft failure after revision ACLR with a >2-fold OR of subsequent graft rupture in revision ACL surgery. Registration: NCT00625885 ( ClinicalTrials.gov identifier).

Anatomic placement of the femoral tunnel by a modified transtibial technique using a large-offset femoral tunnel guide: A cadaveric study

BACKGROUND

The purpose of this study was to assess whether the use of a 10 mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel compared to the conventional seven millimeters-offset guide in transtibial anterior cruciate ligament (ACL) reconstruction.

METHODS

Sixteen knees from eight cadavers were employed. Four guide pins were inserted using a seven millimeters- or 10mm-offset transtibial femoral tunnel guide with or without lateral rotation technique in each knee. The pin positions were assessed by the quadrant method. Femoral tunnels were then reamed along the guide pins inserted through the laterally rotated guides: seven millimeters-offset for right knees and 10 mm- offset for left knees. The percentages of the coverage of native ACL femoral footprints were analyzed.

RESULTS

Lateral rotation of the seven millimeters- & 10mm-offset guides placed the pins more posteriorly (lower) by 15.7% and 24.5%, respectively (p<0.001). Laterally rotated 10 mm-offset guides placed the guide pins more distally by 6.2% and more posteriorly by 6.6% than laterally rotated seven millimeters-offset guides. Laterally rotated seven millimeters- & 10 mm-offset guides resulted in average coverage of 52.3% and 61.8% of the native ACL femoral footprints, respectively (p<0.001). The lengths of the tunnels were acceptable.

CONCLUSION

Compared to the conventional seven millimeters-offset guide, the use of a 10mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel in transtibial ACL reconstruction.

CLINICAL RELEVANCE

Anatomic single bundle ACL reconstruction by transtibial technique seems feasible by using the technique described in this study.

Excursion of bone-patella tendon-bone grafts during the flexion-extension movement in anterior cruciate ligament reconstruction: Comparison between isometric and anatomic reconstruction techniques

Background/objective

The purpose of this study was to elucidate the biomechanical differences between anterior cruciate ligament (ACL) grafts reconstructed by isometric and anatomic reconstruction techniques, based on their length changes.

Methods

One hundred and thirty-three knees with primary ACL reconstruction using the bone-patellar tendon-bone (BTB) graft were retrospectively identified. Twenty-two knees and 111 knees underwent isometric round tunnel (IRT) ACL reconstruction and anatomic rectangular tunnel (ART) ACL reconstruction, respectively.

Results

After femoral-side fixation of the graft in the surgery, the length change of the graft from 120° flexion to full extension was measured by using an isometric positioner at the tibial side. Both reconstructive techniques showed little length change from 120° to ∼20° of flexion, followed by elongation of the graft, until full extension. The amount of length change of the grafts was 1.0 ± 0.7 mm with the IRT technique, and 3.4 ± 0.9 mm with the ART technique. These findings were significantly different, based on the Mann–Whitney U test (p < 0.001).

Conclusion

The native ACL has an intrinsic length change of 3–6 mm, and therefore the ART technique may more closely replicate the biomechanical function of the native ACL.

Biomechanics of the anterior cruciate ligament and implications for surgical reconstruction

Injury to the anterior cruciate ligament (ACL) is regarded as critical to the physiological kinematics of the femoral-tibial joint, its disruption eventually causing long-term functional impairment. Both the initial trauma and the pathologic motion pattern of the injured knee may result in primary degenerative lesions of the secondary stabilisers of the knee, each of which are associated with the early onset of osteoarthritis. Consequently, there is a wide consensus that young and active patients may profit from reconstructing the ACL. Several factors have been identified as significantly influencing the biomechanical characteristics and the functional outcome of an ACL reconstructed knee joint. These factors are: (1) individual choice of autologous graft material using either patellar tendon-bone grafts or quadrupled hamstring tendon grafts, (2) anatomical bone tunnel placement within the footprints of the native ACL, (3) adequate substitute tension after cyclic graft preconditioning, and (4) graft fixation close to the joint line using biodegradable graft fixation materials that provide an initial fixation strength exceeding those loads commonly expected during rehabilitation. Under observance of these factors, the literature encourages mid-to long-term clinical and functional outcomes after ACL reconstruction.

Femoral tunnel placement in anterior cruciate ligament reconstruction: rationale of the two incision technique

Endoscopic anterior cruciate ligament (ACL) reconstruction can be performed through one-incision or two-incision technique. The current one-incision endoscopic ACL single bundle reconstruction techniques attempt to perform an isometric repair placing the graft along the roof of the intercondylar notch, anterior and superior to the native ACL insertion. However the ACL isometry is a theoretical condition, and has not stood up to detailed testing and investigation. Moreover this type of reconstruction results in a vertically oriented non-anatomic graft, which is able to control anterior tibial translation but not the rotational component of the instability. Femoral tunnel obliquity has a great effect on rotational stability. To improve the obliquity of graft, an anatomical ACL reconstruction should be attempt. Anatomical insertion of ACL on the femur lies very low in the notch, spreading between 11 and 9–8 o'clock position and the center lies lower than at 11 o'clock position. Femoral aiming devices through the tibial tunnel aim at an isometric placement, and they do not aim at an anatomic position of the graft. Also, a placement of tunnel in a position of 11 o'clock is unable to restore rotational stability. The two-incision technique, with the possibility to position femoral tunnel independently by tibial tunnel, allows us to place femoral tunnel entrance in a position of 10 'clock that can most accurately reproduce the anatomic behaviour of the ACL and can potentially improve the response of the graft to rotatory loads. This positioning results in a more oblique graft placement, avoiding problem related to PCL impingement during knee flexion. Further studies are required to understand if this kind of reconstruction can ameliorate proprioception as well as clinical outcome at a long-term follow-up.

Anatomic anterior cruciate ligament reconstruction: the two-incision technique

This article describes the anatomical two-incision reconstruction of anterior cruciate ligament (ACL) of knee. The major part of currently single incision tibial endoscopic techniques attempts to reproduce the most isometric anteromedial bundle of ACL. Often a relatively vertical femoral tunnel, respect to the notch, is drilled, which is not really efficacious in providing rotatory stability. The single incision technique was developed to obviate the necessity of the lateral femoral incision and dissection. This technical note describes a two-incision ACL reconstruction using an instrumentation, which avoids a large lateral femoral soft tissue dissection, and discusses the rational use of the two-incision ACL reconstruction technique.

Graft length changes in the bi-socket anterior cruciate ligament reconstruction: comparison between isometric and anatomic femoral tunnel placement

PURPOSE

To compare the length change of grafts in bi-socket anterior cruciate ligament (ACL) reconstruction between isometric and anatomic placement.

TYPE OF STUDY

Case series.

METHODS

The subjects were 110 knees of 110 patients with a mean age of 27 years. All knees were reconstructed using multistranded autogenous semitendinosus tendon and the bi-socket procedure. Of those, 43 knees were reconstructed in the isometric position, around the isometric point (group I) and the remaining 67 in the anatomic position, mimicking the anatomic footprint of ACL (group II). Grouping was performed based on the femoral socket position. Each femoral socket for the anterior medial graft (AMG) and the posterolateral graft (PLG) for the left knee was positioned at 1 o'clock and 2 o'clock to 2:30 in group I, or 2 o'clock and 3 o'clock in group II in the posterior border of the notch. Their positioning for the right knee was at 11 o'clock and 9:30 to 10 o'clock in group I, or 10 o'clock and 9 o'clock in group II. The length changes of grafts were intraoperatively measured while extending the knee from 120 degrees to full extension, using a commercially available isometric positioner. The Student t test was used for statistical analysis.

RESULTS

All the grafts showed the pattern of elongation approaching extension. The length change of AMG and PLG was 1.3+/-0.6 mm and 2.2+/-1.0 mm in the group I, 1.4+/-0.7 mm and 2.5+/-0.9 mm in the group II, respectively. There was no statistically significant difference in the values of AMG (P = .51) and PLG (P = .074) between the 2 groups.

CONCLUSIONS

The length change of ACL grafts placed in the anatomic position was not significantly different from that positioned in the isometric position.

LEVEL OF EVIDENCE

Level IV, case series.

In vitro evaluation of combined graft deformation in anterior cruciate ligament reconstructions

In this paper, we present a simple method of calculating deformation of an anterior cruciate ligament graft in combined elongation, bending and total twisting. We also report our results on these deformations for three types of ligament reconstruction in cadaver knees: two isometric reconstructions, using either a biological bone-patellar tendon-bone autograft or an artificial Trevira prosthesis, and modified over-the-top reconstruction with the prosthesis. The data show that the modified OTT technique produced elongation of the graft equivalent to that of the synthetic isometric technique, but significantly less than isometric reconstruction with the biological graft (p<0.05, ANOVA). Moreover, the grafts were subjected to bending and twisting.

The influence of reverse-thread screw femoral fixation on laxity measurements after anterior cruciate ligament reconstruction with hamstring tendon

In arthroscopically assisted anterior cruciate ligament reconstruction using hamstring tendon graft, the graft rotates slightly as the femoral screw is inserted. Its final position tends to be in the anterior half of the tunnel in right knees, resulting in clinical laxity. To perform identical procedures on left and right knees, a reverse-thread screw was designed for femoral fixation in right knees. We prospectively studied 80 patients undergoing right-knee anterior cruciate ligament reconstruction with hamstring tendon autograft. Thirty-six patients underwent reconstruction with a standard screw and 44 underwent reconstruction with a reverse-thread screw. The same technique, performed by the same surgeon, was used on all patients. At 12 months' follow-up, the average side-to-side differences on arthrometry testing were 2.00 mm for the standard screw group and 0.95 mm for the reverse-thread screw group using a manual maximum test, and 1.66 mm and 1.00 mm, respectively, using the 20-pound test. Both differences were statistically significant. Of the standard group, 23% had a manual maximum difference of 3 mm or more, compared with 8% of the reverse-thread group. A significant difference was found between these two groups for Lachman test (77% with grade 0 for the standard group compared with 92% for the reverse group) but pivot shift and Lysholm knee score were not significantly different. The use of a reverse-thread screw for femoral fixation in right-knee anterior cruciate ligament reconstructions in men significantly decreased laxity at 12 months after surgery compared with standard screw fixation.

Flipped patellar tendon autograft anterior cruciate ligament reconstruction

To determine the efficacy of an anterior cruciate ligament (ACL) graft that customizes length and facilitates anatomic outlet fixation, a prospective study of the "flipped" patellar tendon autograft ACL reconstruction began in 1995. This technique shortens the tendon portion to match the intra-articular length by rotating 1 bone plug 180 degrees proximally onto the tendon, thus flipping the bone plug over its ligamentous insertion. Bioscrews (poly L-lactic acid; Linvatec, Largo, FL) secured the grafts. All patients undergoing this procedure with a minimum 21 months follow-up were reviewed. Preoperative and postoperative Tegner, Lysholm, and IKDC activity scores, and Lachman and pivot shift tests were obtained. Postoperative KT testing and radiographs were obtained. Fifty patients were followed-up for an average of 28 months (range, 21 to 39 months). Average patient age was 34 years (range, 16 to 52 years). Tegner scores increased from 2.0 preoperatively to 6.0 postoperatively. Lysholm scores increased from 46 preoperatively to 93 at follow-up, with 86% excellent (66%) or good (20%). IKDC activity scores increased from 3.1 preoperatively to 1.7 postoperatively. KT manual-maximum difference at follow-up averaged 0.7 mm, with 74% less than 3-mm, 18% 3- to 5-mm, and 8% greater than 5-mm difference. Postoperative Lachman results were 0 in 45 patients and 1+ in 5 patients. Postoperative pivot shift was absent in all but 1 patient. Full extension was achieved in all cases and flexion averaged 136 degrees with no patient having less than 120 degrees flexion. No lytic bone changes or tunnel widening were seen. The flipped patellar tendon autograft reduces graft length to its intra-articular portion, increasing graft stability, isometry, and stiffness, and avoiding tunnel graft mismatch with clinically excellent results.

A technique for resolution of graft-tunnel length mismatch in central third bone-patellar tendon-bone anterior cruciate ligament reconstruction

The existence of graft-tunnel length mismatch in correctly reconstructed anterior cruciate ligament (ACL)-deficient patients can occur due to both anatomic variation and compromised tunnel placement encountered during revision, despite attempts at prevention with accurate measurement techniques. This study reports a method for resolution of graft-tunnel length mismatch during central third bone-patellar tendon-bone ACL reconstruction. The technique involves rotation of the graft to shorten its length. Variation in graft shortening occurs depending on the direction of rotation, with external rotation achieving greater shortening. At 630 degrees of external rotation, approximately 25% shortening of the collagenous portion of the graft can be achieved, which allows for adequate bitunnel interference fixation in most instances. This technique can be used during difficult ACL reconstructions, both primary and revision, and may also have uses in routine reconstructions. Early clinical results are presented.