In vivo graft tension in anatomic double-bundle anterior cruciate ligament reconstruction during active leg-raising motion with the knee splinted

The Role of Bracing in ACL Injuries: The Current Evidentiary State of Play

Anterior cruciate ligament (ACL) injuries and surgeries are both increasing in incidence. A notable rate of reinjury and failure does occur after ACL surgery. As a result, interventions that may reduce ACL injury or reinjury are needed and are active areas of innovation. Knee bracing as a strategy to either prevent primary ACL injury, reduce reinjury, or failure after ACL surgery is common. The evidence for bracing around ACL injuries is not straightforward. Clinicians therefore need to understand the relevant literature on bracing around ACL injuries to make personalized decisions for individuals who may be at risk for ACL injury. The purpose of this review is to provide an overview on bracing for ACL injuries and summarize the current available clinical evidence for its use in ACL injuries.

A Biomechanical Comparison of Single-, Double-, and Triple-Bundle Anterior Cruciate Ligament Reconstructions Using a Hamstring Tendon Graft

PURPOSE

The first objective of our cadaveric study was to perform a biomechanical comparison of single-bundle (SB), double-bundle (DB), and triple-bundle (TB) anterior cruciate ligament (ACL) reconstructions using a hamstring tendon graft to determine the laxity match pre-tension (LMP) value, which is the tension within the graft required to re-create the same anterior laxity as the ACL-intact knee. The second objective was to determine the anterior laxity and force distribution during the application of both an anterior force and a simulated pivot-shift test.

METHODS

Eleven fresh-frozen cadaveric knees were tested using a robotic/universal force-moment sensor system in the intact state, TB-reconstructed knee, DB-reconstructed knee, and SB-reconstructed knee. The LMP in each reconstruction was recorded. Each reconstructed knee was tested with an external load of 100-N anterior drawer and combined rotatory loads of 10-Nm valgus moment and 5-Nm internal rotation. The anterior tibial translation and tensile forces of each graft bundle were measured.

RESULTS

The LMP values for the TB reconstruction were 1.7 N for the anteromedial-medial graft, 1.7 N for the anteromedial-lateral graft, and 3.4 N for the posterolateral graft (PLG). The LMP value was 5.6 N for the anteromedial graft and PLG in the DB reconstruction. The LMP value was 26.3 N for the whole graft in the SB reconstruction. No statistically significant difference in stability was found between TB and DB reconstructions during the anterior load and the combined rotatory load test. For force distribution, the PLG tension in the TB reconstruction was statistically lower than that in the DB reconstruction.

CONCLUSIONS

Anatomic TB ACL reconstruction with the lowest initial tension on the graft stabilized the knee equally to DB or SB reconstruction, which required greater initial tension.

CLINICAL RELEVANCE

Although SB, DB, and TB ACL reconstructions through the anatomic tunnel position could equally restore stability, the initial tension on the graft required to restore stability was less in the latter 2 multi-tunnel reconstructions.

Effect of fixation angle and graft tension in double-bundle anterior cruciate ligament reconstruction on knee biomechanics

PURPOSE

To compare the effect of graft fixation angle and tension in double-bundle anterior cruciate ligament (ACL) reconstruction on knee biomechanics.

METHODS

Fourteen cadaver knees were tested using a robotic system under two loadings: (1) an 89-N anterior tibial load (ATL) at full extension (FE), 15°, 30°, 45°, 60°, and 90°, and (2) combined 7 N m valgus and 5 N m internal tibial torques (simulated pivot-shift test) at FE, 15° and 30°. Four graft fixation angles and tensions were used for the anteromedial (AM) and posterolateral (PL) bundles, respectively: (Recon 1) 30°/20N and FE/20N, (Recon 2) 30°/30N and FE/10N, (Recon 3) 45°/20N and 15°/20N, and (Recon 4) 45°/30N and 15°/10N.

RESULTS

All fixation protocols closely restored the intact knee kinematics under ATL and simulated pivot-shift loading. For the AM bundle under ATL, the in situ force (ISF) with Recon 3 at the FE was significantly lower than that of the intact knee. For the PL bundle under ATL, the ISF with Recon 3 at the FE, 15° and 30° was significantly higher than that of the intact knee. In PL bundle under simulated pivot-shift loading, the ISF with Recon 1 and Recon 2 at FE was lower and the ISF of the PL bundle with Recon 3 at the 15° was higher than that of the intact knee.

CONCLUSION

The AM-45°/30N and PL-15°/10N fixation most closely matched intact knee kinematics; however, stabilizing the knee during anterior tibial translation may risk an imbalance of the AM and the PL bundle loading. The results indicate that ACL bundle forces may not be restored even if the clinical assessment shows good results with the Lachman test and pivot-shift test. This may alter the loading on other structures of the knee.

Effects of initial graft tension on clinical outcome after anatomic double-bundle anterior cruciate ligament reconstruction: comparison of two graft tension protocols

BACKGROUND

In anatomic double-bundle anterior cruciate ligament (ACL) reconstruction, there are great controversies concerning the ideal graft tension protocols. The purpose of this study was to clarify differences in the effect of two graft tension protocols on the clinical outcome after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction by comparing the minimum 2-year clinical results.

METHODS

Ninety-seven patients with unilateral anatomic double-bundle ACL reconstruction were divided into two groups. In the first 44 patients (Group I), a 40-N tension was applied to each of the two hamstring autografts at 30° of knee flexion, and simultaneously fixed onto the tibia. In the remaining 53 patients (Group II), a 30-N tension was applied to each graft at 10° of knee flexion, and simultaneously fixed onto the tibia. Each patient was examined 2 years after surgery.

RESULTS

There wasn't a significant difference in the background of the two groups. There was no significant difference in the postoperative anterior laxity between the two groups. The average was 1.1 mm and 0.9 mm in Groups I and II, respectively. There wasn't any differences between the two groups in Lysholm knee score, International Knee Documentation Committee (IKDC) evaluation and muscle strength. Four patients had loss of knee extension in a range of 5° and 10° in Group I and none of the patients in Group II exhibited any loss in knee extension; which was statistically significant (p = 0.025).

CONCLUSION

The two initial graft tension protocols did not result in any significant differences in the Lysholm knee score and IKDC grade. However, it was noted that the 40-N tension applied to each graft at 30° of knee flexion more significantly induced loss of knee extension in comparison to the 30-N tension applied to each graft at 10°. From a clinical viewpoint, the loss of knee extension is one of the pathological conditions that should be absolutely avoided after ACL reconstruction. Therefore, the 30-N tension applied to each graft at 10° is preferable to the other graft tension protocol.

A Comparison of Ligament Tensions Between Intra- and Extra-Articular Measurement in Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) reconstruction is one of the treatments of ACL injuries. In the surgery, the reconstructed ligament should be properly tensioned to provide a normal ligament behavior. However, the ligament tension has been measured with an extra-articular technique in past studies, while the intra-articular ligament tension is still unknown. The purpose of this study is to compare the ligament tensions between intra- and extra-articular measurements in the ACL reconstruction. Intra-articular measurement employs a micro-force sensor designed with a width and thickness same as those of the reconstructed ligament. This study performed two experiments (i.e., sensor accuracy and cadaveric study). In the sensor accuracy experiment, the accuracy of the sensor was about 3% until an applied force of 100 N. In the cadaveric study, the results of the intra- and extra-articular measurement tensions were 13.6±3.9 N and 18.7±1.3 N (n= 6), respectively. The significant difference in student t-test (p-value was 0.026) between the intra- and extra- articular measurements was observed. The bending angle and friction between the graft and bone tunnel, and the shape of the intra-articular edge of tibial bone tunnel affected the intra-articular measurement in ACL reconstruction.