Sheila J.M. Ingham

Application of the Anatomic Double-Bundle Reconstruction Concept to Revision and Augmentation Anterior Cruciate Ligament Surgeries

Anatomy is the basis of orthopaedic surgery. Our approach to anterior cruciate ligament reconstruction surgery is governed by this principle. In this article, we describe the concept of anatomic anterior cruciate ligament reconstruction as well as its application to single and double-bundle anterior cruciate ligament reconstruction, revision anterior cruciate ligament surgery, and anteromedial and posterolateral-bundle anterior cruciate ligament augmentation surgery. Traditional single-bundle anterior cruciate ligament reconstruction has been shown to achieve good-to-excellent results in only 60% of patients1. As many as 20% to 30% of athletes fail to achieve their previous level of performance, suggesting that there is room for improvement. Because of this high failure rate, we have been driven to explore alternative reconstruction techniques. Our goal is to restore the native anatomy, which we believe will result in superior outcomes and performance levels. Double-bundle anterior cruciate ligament reconstruction is an application of the concept of anatomic reconstruction. Since the native anterior cruciate ligament is composed of two functional bundles, we believe that it is crucial to restore the function of both. The anteromedial bundle is the main contributor to anterior-posterior stability, while the posterolateral bundle mainly controls rotational stability, especially in deep knee flexion2,3. Cadaver biomechanical studies demonstrate that single-bundle reconstruction fails to restore the rotational stability of the knee4, whereas double-bundle anterior cruciate ligament reconstruction effectively restores rotational stability5. Recent Level-I and II short-term studies6-11 also suggest that double-bundle anterior cruciate ligament reconstruction results in superior clinical outcomes. ### Definition of Failure of Anterior Cruciate Ligament Reconstruction We define failure of anterior cruciate ligament reconstruction by both objective and subjective parameters. Objectively, a knee lacking 10° of extension or 10° of flexion or a knee that demonstrates instability and giving-way is considered a failure. Furthermore, we recognize that a patients perception of failure …

Evaluation of the tunnel placement in the anatomical double-bundle ACL reconstruction: a cadaver study

The objective of this study was to investigate the accurate AM and PL tunnel positions in an anatomical double-bundle ACL reconstruction using human cadaver knees with an intact ACL. Fifteen fresh-frozen non-paired adult human knees with a median age of 60 were used. AM and PL bundles were identified by the difference in tension patterns. First, the center of femoral PL and AM bundles were marked with a K-wire and cut from the femoral insertion site. Next, each bundle was divided at the tibial side, and the center of each AM and PL tibial insertion was again marked with a K-wire. Tunnel placement was evaluated using a C-arm radiographic device. For the femoral side assessment, Bernard and Hertel’s technique was used. For the tibial side assessment, Staubli’s technique was used. After radiographic evaluations, all tibias’ soft tissues were removed with a 10% NaOH solution, and tunnel placements were evaluated. In the radiographic evaluation, the center of the femoral AM tunnel was placed at 15% in a shallow–deep direction and at 26% in a high–low direction. The center of the PL bundle was found at 32% in a shallow–deep direction and 52% in a high–low direction. On the tibial side, the center of the AM tunnel was placed at 31% from the anterior edge of the tibia, and the PL tunnel at 50%. The ACL tibial footprint was placed close to the center of the tibia and was oriented sagittally. AM and PL tunnels can be placed in the ACL insertions without any coalition. The native ACL insertion site has morphological variety in both the femoral and tibial sides. This study showed, anatomically and radiologically, the AM and PL tunnel positions in an anatomical ACL reconstruction. We believe that this study will contribute to an accurate tunnel placement during ACL reconstruction surgery and provide reference data for postoperative radiographic evaluation.

Biological approaches to improve skeletal muscle healing after injury and disease

Skeletal muscle injury and repair are complex processes, including well-coordinated steps of degeneration, inflammation, regeneration, and fibrosis. We have reviewed the recent literature including studies by our group that describe how to modulate the processes of skeletal muscle repair and regeneration. Antiinflammatory drugs that target cyclooxygenase-2 were found to hamper the skeletal muscle repair process. Muscle regeneration phase can be aided by growth factors, including insulin-like growth factor-1 and nerve growth factor, but these factors are typically short-lived, and thus more effective methods of delivery are needed. Skeletal muscle damage caused by traumatic injury or genetic diseases can benefit from cell therapy; however, the majority of transplanted muscle cells (myoblasts) are unable to survive the immune response and hypoxic conditions. Our group has isolated neonatal skeletal muscle derived stem cells (MDSCs) that appear to repair muscle tissue in a more effective manner than myoblasts, most likely due to their better resistance to oxidative stress. Enhancing antioxidant levels of MDSCs led to improved regenerative potential. It is becoming increasingly clear that stem cells tissue repair by direct differentiation and paracrine effects leading to neovascularization of injured site and chemoattraction of host cells. The factors invoked in paracrine action are still under investigation. Our group has found that angiotensin II receptor blocker (losartan) significantly reduces fibrotic tissue formation and improves repair of murine injured muscle. Based on these data, we have conducted a case study on two hamstring injury patients and found that losartan treatment was well tolerated and possibly improved recovery time. We believe this medication holds great promise to optimize muscle repair in humans.

Impingement Pressure in the Anatomical and Nonanatomical Anterior Cruciate Ligament Reconstruction A Cadaver Study

Background: Although the literature has extensively discussed impingement after anterior cruciate ligament (ACL) reconstruction, the definition of impingement is vague, and impingement pressure has not been well investigated as a function of tunnel position. Purpose: To determine the amount of impingement pressure between the ACL and posterior cruciate ligament (PCL) and between the ACL and notch roof in the native ACL, the single-bundle ACL reconstruction with different tunnel placements, and the anatomical double-bundle ACL reconstruction. Study design: Controlled laboratory study. Methods: Fifteen fresh-frozen nonpaired human cadaver knees were used. In each knee, different femoral and tibial tunnels were created, which allowed different graft placements. A single graft was placed in 3 positions: tibial anteromedial (AM) to femoral AM (anatomical), tibial posterolateral (PL) to femoral high AM (nonanatomical/mismatch), and tibial AM to femoral high AM. Double grafts were placed in an anatomical fashion (AM to AM and PL to PL). In each case, pressure-measuring films were inserted between the ACL and roof, the ACL and PCL, and the AM and PL bundles (for double-bundle group only). Knees were then moved with 40 N of force and from full flexion to full extension, and the pressure pattern on the film was analyzed. Results: Compared with other groups, only the AM–high AM group showed significantly higher roof impingement pressure (P < .05). There was no significant difference in PCL impingement pressure between the intact ACL group and any of the reconstructed groups. No impingement pressure was observed between the grafts in the anatomical double-bundle ACL reconstruction. Conclusion: This study evaluated the effect of different tunnel placements on the impingement pressure after ACL reconstruction. Anatomical single- or double-bundle ACL reconstruction and nonanatomical tibial PL–femoral high AM ACL reconstruction do not cause roof, PCL, and interbundle impingement. Clinical relevance: Surgeons can perform the anatomical double-bundle ACL, anatomical single-bundle, and nonanatomical tibial PL–femoral high AM reconstructions as impingement-free reconstructions.

Isolation and characterization of human anterior cruciate ligament-derived vascular stem cells.

The anterior cruciate ligament (ACL) usually fails to heal after rupture mainly due to the inability of the cells within the ACL tissue to establish an adequate healing process, making graft reconstruction surgery a necessity. However, some reports have shown that there is a healing potential of ACL with primary suture repair. Although some reports showed the existence of mesenchymal stem cell-like cells in human ACL tissues, their origin still remains unclear. Recently, blood vessels have been reported to represent a rich supply of stem/progenitor cells with a characteristic expression of CD34 and CD146. In this study, we attempted to validate the hypothesis that CD34- and CD146-expressing vascular cells exist in hACL tissues, have a potential for multi-lineage differentiation, and are recruited to the rupture site to participate in the intrinsic healing of injured ACL. Immunohistochemistry and flow cytometry analysis of hACL tissues demonstrated that it contains significantly more CD34 and CD146-positive cells in the ACL ruptured site compared with the noninjured midsubstance. CD34+CD45- cells isolated from ACL ruptured site showed higher expansionary potentials than CD146+CD45- and CD34-CD146-CD45- cells, and displayed higher differentiation potentials into osteogenic, adipogenic, and angiogenic lineages than the other cell populations. Immunohistochemistry of fetal and adult hACL tissues demonstrated a higher number of CD34 and CD146-positive cells in the ACL septum region compared with the midsubstance. In conclusion, our findings suggest that the ACL septum region contains a population of vascular-derived stem cells that may contribute to ligament regeneration and repair at the site of rupture.

Anterior Cruciate Ligament Tunnel Position Measurement Reliability on 3-Dimensional Reconstructed Computed Tomography

PURPOSE The purpose of this study was to evaluate intraobserver and interobserver reliability of anterior cruciate ligament tunnel location measurement by use of 3-dimensional reconstructed computed tomography (CT). METHODS Three-dimensional reconstructed CT images of 31 cadaveric knees were used in this study. Twenty-one knees were operated on with a double-bundle technique, and ten knees were operated on with a single-bundle technique. Femoral tunnel location was measured with 3 methods on the medial-lateral view of the lateral femoral condyle in the strictly lateral position. Tibial tunnel location was measured in the top view of the proximal tibia. The images were evaluated independently by 2 orthopaedic surgeons. A second measurement was performed, by both testers, after a 4-week interval. RESULTS The 3 methods of femoral tunnel location measurement had intraobserver intraclass correlation coefficients (ICCs) that ranged from 0.963 to 0.998 and interobserver ICCs that ranged from 0.993 to 0.999. Tibial tunnel measurement had intraobserver ICCs that varied between 0.957 and 0.998 and interobserver ICCs that varied between 0.993 and 0.996. CONCLUSIONS The measurement of the anterior cruciate ligament tunnel location on 3-dimensional reconstructed CT provided excellent intraobserver and interobserver reliability. CLINICAL RELEVANCE Three-dimensional reconstructed CT can be used for further studies to assess the effect of tunnel position on knee stability and patient outcomes.

Morphology of the tibial insertion of the posterior cruciate ligament.

BACKGROUND It has been demonstrated that double-bundle reconstruction of the posterior cruciate ligament restores knee kinematics better than does single-bundle reconstruction. The objective of this study was to identify the tibial insertion site of the posterior cruciate ligament and the related osseous landmarks to help guide surgeons in the performance of an anatomical double-bundle reconstruction of the posterior cruciate ligament. METHODS Twenty-one unpaired human cadaver knees were evaluated. The geometric data and surface features of the tibial insertion site of the posterior cruciate ligament and its bundles were studied with macroscopic observation and with three-dimensional laser photography. RESULTS The mean surface areas (and standard deviations) of the anterolateral and posteromedial insertion sites were 93.1+/-16.6 mm2 and 150.8+/-31.0 mm2, respectively, and the distance between their centers was 8.2+/-1.3 mm. The mean length and width of the anterolateral insertion site were 7.8+/-1.5 mm and 9.2+/-1.6 mm, and the mean length and width of the posteromedial insertion site were 9.4+/-1.4 mm and 15.0+/-2.7 mm. The average distances from the anterior and medial margins of the tibial plane to the center of the anterolateral insertion, defined as percentage ratios of the anteroposterior and mediolateral dimensions, were 83.4%+/-3.4% and 47.1%+/-1.9%, respectively, and the average distances from the anterior and medial margins of the tibial plane to the center of the posteromedial insertion were 95.5%+/-1.9% and 43.8%+/-2.2%. A notable change in angle, of >10 degrees, was observed between the anterolateral and posteromedial slopes in sixteen of the twenty-one knees. The average angle between the anterolateral and posteromedial slopes was 14.5 degrees+/-6.4 degrees. CONCLUSIONS The tibial insertion site of the posterior cruciate ligament and its bundles is very complex. However, the shapes and positions of the insertion sites of the two bundles are consistent in that they are located in different planes on the posterior intercondylar fossa. We noted a consistent change in slope between the tibial insertion sites of the anterolateral and posteromedial bundles.

Intercondylar roof impingement pressure after anterior cruciate ligament reconstruction in a porcine model

Anterior cruciate ligament (ACL) graft impingement against the intercondylar roof has been postulated, but not thoroughly investigated. The roof impingement pressure changes with different tibial and femoral tunnel positions in ACL reconstruction. Anterior tibial translation is also affected by the tunnel positions of ACL reconstruction. The study design included a controlled laboratory study. In 15 pig knees, the impingement pressure between ACL and intercondylar roof was measured using pressure sensitive film before and after ACL single bundle reconstruction. ACL reconstructions were performed in each knee with two different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM to AM) and (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL to High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. Neither the AM to AM nor the PL to High-AM ACL reconstruction groups showed significant difference when compared with intact ACL in roof impingement pressure. The AM to AM group had a significantly higher failure load than PL to High-AM group. This study showed how different tunnel placements affect the ACL-roof impingement pressure and anterior-posterior laxity in ACL reconstruction. Anatomical ACL reconstruction does not cause roof impingement and it has a biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in the pig knee. There is no intercondylar roof impingement after anatomical single bundle ACL reconstruction.

Changes in ACL length at different knee flexion angles: an in vivo biomechanical study

Recently, there has been a tremendous impetus on anatomical reconstruction of the anterior cruciate ligament (ACL), and the double-bundle reconstruction concept has been advocated by many authors. It is, therefore, important to understand how the lengths of the two bundles of the ACL vary during different knee flexion angles as this could influence the angle of graft fixation during surgery. The aim of this study is to determine the change in length of the ACL bundles during different knee flexion angles. Ten subjects with normal knees were evaluated. A high-resolution computer tomography scan was performed, and 3D knee images were obtained. These images were then imported to customized software, and digital length measurement of four virtual bundles (anatomical single bundle, AM, PL and over the top) was evaluated from fixed points on the femur and tibia. Length-versus-flexion curves were drawn, and statistical analysis was performed to evaluate changes in length for each bundle at varying angles of knee flexion (0°, 45°, 90° and 135°). All virtual bundles achieved greatest lengths at full extension. There was a significant difference between the posterolateral bundle length when compared to the other bundles at full extension. There were no significant differences between the lengths of the anteromedial and the over the top single bundles at all angles of knee flexion. Three-dimensional computer tomography can be used to assess the length changes of the virtual anterior cruciate ligament bundles, thereby allowing a better understanding of bundle function in clinical situations.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Restores Patellofemoral Contact Areas and Pressures More Closely Than Nonanatomic Single-Bundle Reconstruction

PURPOSE To investigate the effects of anterior cruciate ligament (ACL) deficiency and nonanatomic single-bundle (SB) and anatomic double-bundle (DB) ACL reconstruction on the contact characteristics of the patellofemoral (PF) joint. METHODS By use of a materials testing system, 7 fresh-frozen human cadaveric knees were tested. The following states were tested: ACL-intact knee, nonanatomic SB ACL reconstruction, anatomic DB ACL reconstruction, and ACL-deficient knee. Hamstring autografts were used. PF contact pressures and areas were measured with pressure-sensitive film at 30°, 60°, and 90° of knee flexion with a constant 100-N load on the quadriceps tendon. RESULTS The total contact area of ACL-deficient and nonanatomic SB ACL-reconstructed knees (123.8 ± 63.9 and 149.6 ± 79.3 mm(2), respectively) significantly decreased when compared with those of the intact knee (206.1 ± 83.6 mm(2)) at 30° of knee flexion. The lateral-facet peak pressure of ACL-deficient and nonanatomic SB ACL-reconstructed knees (1.12 ± 0.52 and 1.22 ± 0.54 MPa, respectively) significantly decreased when compared with those of the intact knee (0.68 ± 0.38 MPa) at 90° of knee flexion. Anatomic DB ACL reconstruction restored the contact pressures and areas to values similar to those of the intact knee (no significant difference). CONCLUSIONS ACL deficiency resulted in a significant decrease in the total and medial PF contact areas and in an increase in the lateral PF contact pressure. Anatomic DB ACL reconstruction more closely restored normal PF contact area and pressure than did nonanatomic SB ACL reconstruction. CLINICAL RELEVANCE Our findings suggest that the changes in the PF contact area and pressures in ACL deficiency and after nonanatomic SB ACL reconstruction may be one of the causes of PF osteoarthritis or other related PF problems found at long-term follow-up. Anatomic DB ACL reconstruction may reduce the incidence of PF problems by closely restoring the contact area and pressure.