Sebastian Kopf

The Location of Femoral and Tibial Tunnels in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Analyzed by Three-Dimensional Computed Tomography Models

BACKGROUND Characterization of the insertion site anatomy in anterior cruciate ligament reconstruction has recently received increased attention in the literature, coinciding with a growing interest in anatomic reconstruction. The purpose of this study was to visualize and quantify the position of anatomic anteromedial and posterolateral bone tunnels in anterior cruciate ligament reconstruction with use of novel methods applied to three-dimensional computed tomographic reconstruction images. METHODS Careful arthroscopic dissection and anatomic double-bundle anterior cruciate ligament tunnel drilling were performed with use of topographical landmarks in eight cadaver knees. Computed tomography scans were performed on each knee, and three-dimensional models were created and aligned into an anatomic coordinate system. Tibial tunnel aperture centers were measured in the anterior-to-posterior and medial-to-lateral directions on the tibial plateau. The femoral tunnel aperture centers were measured in anatomic posterior-to-anterior and proximal-to-distal directions and with the quadrant method (relative to the femoral notch). RESULTS The centers of the tunnel apertures for the anteromedial and posterolateral tunnels were located at a mean (and standard deviation) of 25% +/- 2.8% and 46.4% +/- 3.7%, respectively, of the anterior-to-posterior tibial plateau depth and at a mean of 50.5% +/- 4.2% and 52.4% +/- 2.5% of the medial-to-lateral tibial plateau width. On the medial wall of the lateral femoral condyle in the anatomic posterior-to-anterior direction, the anteromedial and posterolateral tunnels were located at 23.1% +/- 6.1% and 15.3% +/- 4.8%, respectively. The proximal-to-distal locations were at 28.2% +/- 5.4% and 58.1 +/- 7.1%, respectively. With the quadrant method, anteromedial and posterolateral tunnels were measured at 21.7% +/- 2.5% and 35.1% +/- 3.5%, respectively, from the proximal condylar surface (parallel to the Blumensaat line), and at 33.2% +/- 5.6% and 55.3% +/- 5.3% from the notch roof (perpendicular to the Blumensaat line). Intraobserver and interobserver reliability was high, with small standard errors of measurement. CONCLUSIONS This cadaver study provides reference data against which tunnel position in anterior cruciate ligament reconstruction can be compared in future clinical trials.

Nonanatomic tunnel position in traditional transtibial single-bundle anterior cruciate ligament reconstruction evaluated by three-dimensional computed tomography.

BACKGROUND Transtibial drilling techniques are widely used for arthroscopic reconstruction of the anterior cruciate ligament, most likely because they simplify femoral tunnel placement and reduce surgical time. Recently, however, there has been concern that this technique results in nonanatomically positioned bone tunnels, which may cause abnormal knee function. The purpose of this study was to use three-dimensional computed tomography models to visualize and quantify the positions of femoral and tibial tunnels in patients who underwent traditional transtibial single-bundle reconstruction of the anterior cruciate ligament and to compare these positions with reference data on anatomical tunnel positions. METHODS Computed tomography scans were performed on thirty-two knees that had undergone transtibial single-bundle reconstruction of the anterior cruciate ligament. Three-dimensional computed tomography models were aligned into an anatomical coordinate system. Tibial tunnel aperture centers were measured in the anterior-to-posterior and medial-to-lateral directions on the tibial plateau. Femoral tunnel aperture centers were measured in anatomic posterior-to-anterior and proximal-to-distal directions and with the quadrant method. These measurements were compared with reference data on anatomical tunnel positions. RESULTS Tibial tunnels were located at a mean (and standard deviation) of 48.0% +/- 5.5% of the anterior-to-posterior plateau depth and a mean of 47.8% +/- 2.4% of the medial-to-lateral plateau width. Femoral tunnels were measured at a mean of 54.3% +/- 8.3% in the anatomic posterior-to-anterior direction and at a mean of 41.1% +/- 10.3% in the proximal-to-distal direction. With the quadrant method, femoral tunnels were measured at a mean of 37.2% +/- 5.5% from the proximal condylar surface (parallel to the Blumensaat line) and at a mean of 11.3% +/- 6.6% from the notch roof (perpendicular to the Blumensaat line). Tibial tunnels were positioned medial to the anatomic posterolateral position (p < 0.001). Femoral tunnels were positioned anterior to both anteromedial and posterolateral anatomic tunnel locations (p < 0.001 for both). CONCLUSIONS AND CLINICAL RELEVANCE Transtibial anterior cruciate ligament reconstruction failed to accurately place femoral and tibial tunnels within the native anterior cruciate ligament insertion site. If anatomical graft placement is desired, transtibial techniques should be performed only after careful identification of the native insertions. If anatomical positioning of the femoral tunnel cannot be achieved, then an alternative approach may be indicated.

A systematic review of the femoral origin and tibial insertion morphology of the ACL

Transtibial single bundle anterior cruciate ligament (ACL) reconstruction has been the gold standard for several years. This technique often fails to restore native ACL femoral origin and tibial insertion anatomy of the ACL. Recently, there is a strong trend towards a more anatomical approach in single and double bundle ACL reconstruction. Using the anatomic double bundle structure of the ACL as a principle, the entirety of both tibial insertion and femoral origin of both bundles, the posterolateral and anteromedial, may be restored. Reflected by recent publications over the past two years, there is an increasing interest in the anatomy of the ACL. In the current study, a PubMed literature search was performed looking for measurements of the ACL femoral origin and tibial insertion. These studies show a large variability in the size and the anatomy of the femoral origin and tibial ACL insertion using different methods and specimens. The diversity of reported measurements makes clinical application of these data difficult at best. Thus, it is of paramount importance to understand the individual variations in size and shape of the ACL femoral origin and tibial ACL insertion. This study is a systematic review of the morphology of the ACL femoral origin and tibial insertion as reported in the literature.

Size Variability of the Human Anterior Cruciate Ligament Insertion Sites

Background: Current trends in anterior cruciate ligament reconstruction (ACLR) have been toward anatomical reconstruction that restores the normal size and location of the anterior cruciate ligament insertions and its 2 bundles, the posterolateral (PL) and anteromedial (AM) bundles. This has resulted in a more individualized approach to ACLR. Several studies have shown that the size of the anterior cruciate ligament insertion sites is variable; however, these studies are limited by use of relatively small sample sizes and cadaveric specimens. Purpose: This study was undertaken to evaluate the in vivo size variability of the anterior cruciate ligament insertion sites and its AM and PL bundles during arthroscopy in a large series of patients and to correlate these findings with individuals’ physical characteristics (height, weight, and body mass index). Study Design: Cross-sectional study; Level of evidence, 3. Methods: In 137 patients undergoing ACLR during the first 6 months after injury, the femoral and tibial anterior cruciate ligament insertion sites and the 2 bundles were identified, marked with electrocautery, and measured with an arthroscopic ruler. Additionally, physical characteristics of the patients, including self-reported height, weight, and body mass index, were recorded. Results: The tibial anterior cruciate ligament insertion site had a mean length of 17.0 ± 2.0 mm. The tibial AM bundle length was 9.1 ± 1.2 mm and the width was 9.2 ± 1.1 mm. The tibial PL bundle insertion site length averaged 7.4± 1.0 mm and the width averaged 7.0 ± 1.0 mm. The femoral insertion sites had a mean length of 16.5 ± 2.0 mm. The length of the femoral AM bundle insertion site averaged 9.2 ± 1.2 mm and the width averaged 8.9 ± 0.9 mm. The femoral PL bundle insertion site length averaged 7.1 ± 1.1 mm and the width averaged 6.9 ± 1.0 mm. There were significant positive correlations between patient height and weight (P < .05) with femoral and tibial anterior cruciate ligament insertion site length, tibial PL bundle insertion site length, femoral AM bundle insertion site length, and tibial AM bundle and PL bundle insertion site areas. However, the coefficients of determination values were low (1.0% to 19.4%). Conclusion: There is a large variation in size of the anterior cruciate ligament insertion sites and the AM and PL bundles. Additionally, there are significant but weak correlations between the size of the insertions and height, weight, and body mass index of the individual patient.

The ability of 3 different approaches to restore the anatomic anteromedial bundle femoral insertion site during anatomic anterior cruciate ligament reconstruction.

PURPOSE The purpose of this study was to determine whether drilling the femoral tunnel when performing anterior cruciate ligament (ACL) reconstruction through the accessory medial portal, as opposed to drilling the tunnel transtibially, will lead to more frequent location of the anteromedial femoral tunnel within the anatomic anteromedial bundle insertion site. METHODS Primary anatomic double-bundle reconstruction was performed on 113 patients. Intraoperatively, we placed a guide pin through the anteromedial and posterolateral tibial tunnels and accessory medial portal, attempting to reach the center of the native femoral anteromedial bundle insertion. For each approach, the position of the guide pin was classified as (1) within the center of, (2) off-center within, or (3) outside of the femoral anteromedial insertion. RESULTS There were significant differences in the ability of each approach to reach the center of the femoral anteromedial bundle insertion. Through the tibial anteromedial tunnel, the femoral anteromedial insertion center was reached in 4.4% of cases, whereas it was off-center within and outside of the femoral anteromedial insertion in 23.0% and 72.6%, respectively. Through the tibial posterolateral tunnel, the femoral anteromedial insertion center was reached in 60.2% of cases, whereas it was off-center within and outside of the femoral anteromedial insertion in 23.9% and 15.9% of cases, respectively. When approached from the accessory medial portal, the center of the femoral anteromedial insertion was reached in 100% of the cases. Ultimately, the femoral anteromedial tunnel was drilled through the tibial anteromedial tunnel in 0.9%, through the posterolateral tunnel in 62.8%, and through the accessory medial portal in 36.3% of cases. CONCLUSIONS Drilling the femoral tunnel for the anteromedial graft through the accessory medial portal, as opposed to drilling the tunnel transtibially, leads to more frequent location of the anteromedial femoral tunnel within the anterior cruciate ligament anteromedial bundle anatomic footprint.

Therapeutic potential of anterior cruciate ligament-derived stem cells for anterior cruciate ligament reconstruction.

We recently reported that the ruptured regions of the human anterior cruciate ligament (ACL) contained vascular-derived stem cells, which showed the potential for high expansion and multilineage differentiation. In this study, we performed experiments to test the hypothesis that ACL-derived CD34+ cells could contribute to tendon–bone healing. ACL-derived cells were isolated from the rupture site of human ACL by fluorescence-activated cell sorting. Following ACL reconstruction, immunodeficient rats received intracapsular administration of either ACL-derived CD34+ cells, nonsorted (NS) cells, CD34- cells, or phosphate-buffered saline (PBS). We also performed in vitro cell proliferation assays and enzyme-linked immunosorbent assays for vascular endothelial growth factor (VEGF) secretion. We confirmed the recruitment of the transplanted cells into the perigraft site after intracapuslar injection by immunohistochemical staining at week 1. Histological evaluation showed a greater area of collagen fiber formation and more collagen type II expression in the CD34+ group than the other groups at the week 2 time point. Immunostaining with isolectin B4 and rat osteocalcin demonstrated enhanced angiogenesis and osteogenesis in the CD34+ group at week 2. Moreover, double immunohistochemical staining for human-specific endothelial cell (EC) and osteoblast (OB) markers at week 2 demonstrated a greater ability of differentiation into ECs and OBs in the CD34+ group. Microcomputerized tomography showed the greatest healing of perigraft bone at week 4 in the CD34+ cell group, and the failure load of tensile test at week 8 demonstrated the greatest biomechanical strength in the CD34+ group. Furthermore, the in vitro studies indicated that the CD34+ group was superior to the other groups in their cell proliferation and VEGF secretion capacities. We demonstrated that ACL-derived CD34+ cells contributed to the tendon–bone healing after ACL reconstruction via the enhancement of angiogenesis and osteogenesis, which also contributed to an increase in biomechanical strength.

Local treatment of meniscal lesions with vascular endothelial growth factor.

BACKGROUND The healing potential in the avascular regions of the meniscus is very limited, and improving the vascularity might be a reasonable way to improve healing. Vascular endothelial growth factor (VEGF) is one of the most potent proangiogenetic factors. We hypothesized that the local application of VEGF(165) would (1) improve the healing of a lesion in the avascular region of the meniscus, (2) induce angiogenesis in both the avascular and vascular regions, and (3) increase the amounts of VEGF mRNA and VEGF. METHODS In eighteen sheep, the medial menisci were cut longitudinally in the avascular region and were sutured. Three groups were established depending on the suture material: (1) uncoated Ethibond, (2) Ethibond coated with VEGF(165) and its carrier Poly(D,L-Lactide) (PDLLA), and (3) Ethibond coated with PDLLA. The contralateral medial menisci served as a control group. Each of the three suture type groups included six animals. After eight weeks, the sheep were killed, and the menisci were examined macroscopically. Immunohistochemistry of Factor VIII and VEGF and real-time reverse-transcription polymerase chain reaction (RT-PCR) of VEGF mRNA were performed. Additionally, the VEGF release kinetics from the VEGF/PDLLA-coated suture were evaluated in vitro. RESULTS In this model, VEGF did not improve meniscal healing. It did not increase angiogenesis in the avascular or vascular region, the VEGF concentration, or the amount of VEGF mRNA. VEGF release from the coated suture peaked on Day 3 and was nearly zero on Day 9. CONCLUSIONS The local application of VEGF(165) as eluted from suture did not increase meniscal angiogenesis or improve meniscal healing. In addition, there was no effect on the amount of VEGF mRNA and VEGF. The VEGF carrier (PDLLA) may have been inadequate because of the short duration of VEGF supply.

Meniscal Root Suturing Techniques: Implications for Root Fixation

Background: Meniscal root tears have attracted increasing interest in recent years. Fixation is an important factor for rehabilitation and avoidance of early failure. Suture fixations have been the most commonly used techniques. The current study aimed to evaluate the maximum failure load of the native meniscal roots (anteromedial, posteromedial, anterolateral, and posterolateral) and of 3 commonly used meniscal root fixation techniques (2 simple stitches, modified Kessler stitch, and loop stitch). Hypotheses: (1) There will be no difference in maximum failure load between the native meniscal roots. (2) The loop stitch will sustain the greatest maximum load to failure, followed by the modified Kessler stitch and the 2 simple stitches. (3) The maximum failure load of the native meniscal roots will not be restored by the tested fixation methods. Study Design: Controlled laboratory study. Methods: The maximum failure load of the 4 human native meniscal roots was evaluated using 64 human meniscal roots. Additionally, the maximum failure load of the 3 fixation techniques was evaluated on 24 meniscal roots: (1) 2 simple stitches, (2) modified Kessler stitch, and (3) loop stitch using a suture shuttle. Results: The average maximum failure load of the native meniscal roots was 594 ± 241 N (anterolateral: 692 ± 304 N; posterolateral: 648 ± 140 N; anteromedial: 407 ± 180 N; posteromedial: 678 ± 200 N). The anteromedial root was significantly weaker than the posterolateral and posteromedial roots (P = .04 and P = .01, respectively). Regarding fixation techniques, the maximum failure load of the 2 simple stitches was 64.1 ± 22.5 N, the modified Kessler stitch was 142.6 ± 33.3 N, and the loop was 100.9 ± 41.6 N. None of the fixation techniques recreated the strength of the native roots. Conclusion: The native anterolateral root was the strongest meniscal root, and the anteromedial root was the weakest meniscal root. Regarding primary fixation strength, the modified Kessler stitch was the strongest technique compared with the loop and the 2 simple stitches. Clinical Relevance: None of our tested fixation methods restored the strength of native meniscal roots. Thus, rehabilitation after meniscal root fixation should proceed cautiously.

Effect of tibial drill angles on bone tunnel aperture during anterior cruciate ligament reconstruction.

BACKGROUND Anatomic reconstruction of the anterior cruciate ligament has received greater attention as patient outcome assessment has become increasingly sophisticated. A goal during anatomic reconstruction should be the creation of a tibial tunnel aperture that is similar in size and orientation to the native anterior cruciate ligament insertion. Aperture morphology depends primarily on three factors: (1) drill-bit diameter, (2) the angle at which the tunnel intersects the tibial plateau (drill-guide angle), and (3) the tibial tunnel orientation in the transverse plane (transverse drill angle). We evaluated the influence of the aforementioned factors on tibial bone-tunnel aperture size and orientation. METHODS With use of various drill-bit diameters at different drill-guide angles, tunnel aperture areas were calculated on the basis of an elliptical shape. The change in tunnel aperture orientation within the transverse plane (along the tibial plateau surface) was quantified by calculating the change in anteroposterior and mediolateral lengths of the aperture. RESULTS Use of a 9-mm drill-bit at a 45 degrees drill-guide angle created a 90-mm(2) bone-tunnel aperture area. Decreasing the drill-guide angle from 65 degrees to 30 degrees resulted in an increase in area of 81%. An aperture oriented 45 degrees relative to the orientation of the native insertion of the anterior cruciate ligament in the transverse plane fell short of the anatomic anteroposterior distance by 2.3 mm and exceeded the mediolateral distance by 1.4 mm on the basis of a 9-mm drill-bit at a drill-guide angle of 45 degrees. CONCLUSIONS During anterior cruciate ligament reconstruction, the drill-bit diameter, sagittal drill angle, and transverse drill angle can all affect tibial tunnel aperture size and orientation. An improperly sized and oriented tunnel aperture may increase the risk of damaging surrounding structures. An optimal combination of these parameters should be chosen during anatomic reconstruction of the anterior cruciate ligament.

Rotatory knee laxity tests and the pivot shift as tools for ACL treatment algorithm.

AbstractThe goal of anterior cruciate ligament (ACL) reconstruction surgery is to eliminate the pivot shift phenomenon. Different injury mechanisms and injury patterns may lead to specific knee laxity patterns. Computer navigation is helpful for the surgeon during examination under anesthesia. Surgical treatment may have to be altered if high-grade laxity is detected preoperatively for example by utilizing a computer navigation that is a helpful adjunct for surgeons during examination under anesthesia. A typical case for revision ACL reconstruction is presented. This article describes several techniques of laxity assessments. Based on the type and degree of pathologic laxity, a treatment algorithm has been developed. Level of evidence V.