ACL Graft Position Affects in Situ Graft Force Following ACL Reconstruction.

BACKGROUND: The purpose of our study was to evaluate the relationship between graft placement and in situ graft force after anterior cruciate ligament (ACL) reconstruction. METHODS: Magnetic resonance imaging (MRI) was obtained for twelve human cadaveric knees. The knees, in intact and deficient-ACL states, were subjected to external loading conditions as follows: an anterior tibial load of 89 N at 0°, 15°, 30°, 45°, 60°, and 90° of flexion and a combined rotatory (simulated pivot-shift) load of 5 Nm of internal tibial torque and 7 Nm of valgus torque at 0°, 15°, and 30° of flexion. Three ACL reconstructions were performed in a randomized order: from the center of the tibial insertion site to the center of the femoral insertion site (Mid), the center of the tibial insertion site to a more vertical femoral position (S1), and the center of the tibial insertion site to an even more vertical femoral position (S2). The reconstructions were tested following the same protocol used for the intact state, and graft in situ force was calculated for the two loadings at each flexion angle. MRI was used to measure the graft inclination angle after each ACL reconstruction. RESULTS: The mean inclination angle (and standard deviation) was 51.7° ± 5.0° for the native ACL, 51.6° ± 4.1° for the Mid reconstruction (p = 0.85), 58.7° ± 5.4° for S1 (p < 0.001), and 64.7° ± 6.5° for S2 (p < 0.001). At 0°, 15°, and 30° of knee flexion, the Mid reconstruction showed in situ graft force that was closer to that of the native ACL during both anterior tibial loading and simulated pivot-shift loading than was the case for S1 and S2 reconstructions. At greater flexion angles, S1 and S2 had in situ graft force that was closer to that of the native ACL than was the case for the Mid reconstruction. CONCLUSIONS: Anatomic ACL reconstruction exposes grafts to higher loads at lower angles of knee flexion. CLINICAL RELEVANCE: Rehabilitation and return to sports progression may need to be modified to protect an anatomically placed graft after ACL reconstruction.

Use of a fluoroscopic overlay to guide femoral tunnel placement during posterior cruciate ligament reconstruction.

BACKGROUND: Intraoperative recognition of the local anatomy of the posterior cruciate ligament (PCL) is difficult for many surgeons, and correct positioning of the graft can be challenging. PURPOSE: To investigate the efficacy of an overlay system based on fluoroscopic landmarks in guiding femoral tunnel placement during PCL reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty cadaveric knees were arthroscopically prepared, and their PCL femoral insertion sites were digitized. The digitized images were co-registered to computed tomography-acquired 3-dimensional bone models. Twenty surgeons with diverse backgrounds performed simulated arthroscopic reconstruction of the anterolateral (AL) and posteromedial (PM) bundles of the PCL, first without and then with the aid of a lateral fluoroscopic image on which the position of a target insertion site based on literature data was displayed as an overlay. The surgeons were allowed to adjust tunnel placement in accordance with the displayed target position. A 3-way comparison was made of the tunnel positions placed by the surgeons, the native insertion site positions, and the literature-based positions. RESULTS: The overlay system was effective in helping surgeons to improve femoral tunnel placement toward the target and toward the anatomic insertion site (P < .05). For femoral AL tunnel placement, surgeons needed 2.35 ± 2.21 extra attempts, which added an extra 80.00 ± 67.95 seconds to the procedure. For PM tunnel placement, surgeons needed 1.80 ± 1.88 extra attempts, adding 66.00 ± 70.82 seconds to the simulated surgery. In their first attempts, more than half of the surgeons positioned either the AL or PM femoral tunnel >5 mm from the native insertion site. With the use of the overlay, 70% of the surgeons were <5 mm away from the PM and 75% from the AL native insertion site. CONCLUSION: The use of a fluoroscopic overlay to guide intraoperative placement of the femoral tunnel(s) during PCL reconstruction can result in more anatomic reconstructions and therefore assist in re-creating native knee kinematics after PCL reconstruction. CLINICAL RELEVANCE: Intraoperative fluoroscopy is an effective, easy, and safe method for improving femoral tunnel positioning during PCL reconstruction.

Individualized ACL reconstruction.

UNLABELLED: The pivot shift test is the only physical examination test capable of predicting knee function and osteoarthritis development after an ACL injury. However, because interpretation and performance of the pivot shift are subjective in nature, the validity of the pivot shift is criticized for not providing objective information for a complete surgical planning for the treatment of rotatory knee laxity. The aim of ACL reconstruction was eliminating the pivot shift sign. Many structures and anatomical characteristics can influence the grading of the pivot shift test and are involved in the genesis and magnitude of rotatory instability after an ACL injury. The objective quantification of the pivot shift may be able to categorize knee laxity and provide adequate information on which structures are affected besides the ACL. A new algorithm for rotational instability treatment is presented, accounting for patients' unique anatomical characteristics and objective measurement of the pivot shift sign allowing for an individualized surgical treatment. LEVEL OF EVIDENCE: V.

Comparison of three non-invasive quantitative measurement systems for the pivot shift test.

PURPOSE: The purpose of this study was to evaluate three different non-invasive measuring devices for the pivot shift phenomenon with reference to direct bony movement measured by an electromagnetic device rigidly attached to the tibia and femur. METHODS: A lower body cadaveric specimen was prepared to create a positive pivot shift in both knees. Twelve expert knee surgeons from worldwide performed their preferred pivot shift technique three times in each knee. After watching an instructional video, the examiners used a standardized technique to perform three additional pivot shift maneuvers in each knee. An electromagnetic tracking system, rigidly attached to femur and tibia, was used to provide reference measurements during the pivot shift test. Three different devices were correlated to the reference method and evaluated in this study: (1) Electromagnetic tracking system with skin sensors; (2) Triaxial accelerometer system; (3) Simple image analysis. RESULTS: When results from both pivot shift techniques (preferred and standardized) were combined, the electromagnetic tracking system with skin sensors showed positive correlation with the reference measurement for acceleration and translation parameters (r = 0.88 and r = 0.67, respectively; both P < 0.01); The triaxial accelerometer system demonstrated good correlation with the reference measurement for acceleration (r = 0.75; P < 0.001). The image analysis system was poorly correlated to the translation of the reference measurement (r = 0.24; P < 0.01). CONCLUSION: The electromagnetic tracking system with skin sensors provided the best correlation with the reference method. The triaxial accelerometer showed also a good correlation and the image analysis system showed a positive, but poor correlation with the reference method. More research is needed in order to validate simple and non-invasive devices for clinical application.

Individualized anatomic anterior cruciate ligament reconstruction.

Arthroscopic anterior cruciate ligament reconstruction (ACL-R) is a technique that continues to evolve. Good results have been established with respect to reducing anteroposterior laxity. However, these results have come into question because nonanatomic techniques have been ineffective at restoring knee kinematics and raised concerns that abnormal kinematics may impact long-term knee health. Anatomic ACL-R attempts to closely reproduce the patient's individual anatomic characteristics. Measurements of the patient's anatomy help determine graft choice and whether anatomic reconstruction should be performed with a single- or double-bundle technique. The bony landmarks and insertions of the anterior cruciate ligament (ACL) are preserved to assist with anatomic placement of both tibial and femoral tunnels. An anatomic single- or double-bundle reconstruction is performed with a goal of reproducing the characteristics of the native ACL. Long-term outcomes for anatomic ACL reconstruction are unknown. By individualizing ACL-R, we strive to reproduce the patient's native anatomy and restore knee kinematics to improve patient outcomes.

Advances in the three-portal technique for anatomical single- or double-bundle ACL reconstruction.

PURPOSE: To describe the "three-portal technique for anatomical ACL single- or double-bundle reconstruction" and the arthroscopic viewing improvement provided by this technique. METHODS: A "high" anterolateral portal was placed 1 cm lateral to the patellar tendon and the most inferior portion of the portal at the level of the inferior pole of the patella. A "central" portal was placed using a spinal needle under arthroscopic visualization following the orientation of the previous ACL fibers. An accessory medial portal was also placed using a spinal needle respecting a 2-mm distance to the medial femoral condyle. RESULTS: The "high" anterolateral portal permitted a broad and unobstructed view of the ACL tibial attachment. The "central" portal allowed a straightforward view of the ACL femoral remnant and bony landmarks in the intercondylar notch. The accessory medial portal enabled to reach the femoral native insertion site of the ACL. CONCLUSION: The three-portal technique provides a proper view of the soft tissue remnants and bony landmarks facilitating an anatomical positioning of the graft.