Effects of modified trans-tibial versus trans-portal technique on stress patterns around the femoral tunnel in anatomical single-bundle ACL reconstruction with different knee flexion angles using finite element analysis

The healing effect of the all inside technique is superior to the traditional technique in the reconstruction of the anterior cruciate ligament

Our main objective was to examine the curative effect of all inside technique and traditional technique in anterior cruciate ligament (ACL) reconstruction. In our retrospective study at the First People's Hospital of Jiashan County, we analyzed 88 participants with ACL injuries (50 males, 38 females, average age 27 years). They were randomly divided into two groups: traditional ACL reconstruction (42 participants) and all inside ACL reconstruction (46 participants). We measured and recorded the Visual Analog Scores (VAS), International Knee Documentation Committee (IKDC), Lysholm scores, operation time, graft diameter and length between the traditional technique group and all inside technique group. There were statistically significant differences in the Lysholm scores and IKDC scores between traditional and all inside technique groups. The all inside technique showed a higher efficacy and effective post-operative recovery with minimal pain and recurrent injuries. Our findings showed that the differences in gender, age, side of injury and operation time were not significant (p> 0.05). Follow-up was conducted at 6 months and 12 months post operations (mean, 7.5 ± 1.1 months). All inside technique minimizing tissue disruption, optimizing graft placement and facilitating early recovery have a significant impact on patient outcomes.

Distribution of bone tunnel positions and treatment efficacy of bone landmark positioning method for anatomical reconstruction of the anterior cruciate ligament: a case control study

BACKGROUND

This study aimed to investigate the distribution of femoral tunnel and explore the influences of bone tunnel positions on knee functions. The bone landmark positioning method was used to position the femoral tunnel during the anatomical reconstruction surgery in patients with anterior cruciate ligament (ACL) rupture.

METHODS

Data of patients who underwent anatomical reconstruction of the ACL between January 2015 and July 2018, were retrospectively analyzed. The distribution of the femoral tunnel was recorded on 3-D CT after surgery. The tunnel positions were classified into good and poor position groups based on whether the position was in the normal range (24-37% on the x-axis and 28-43% on the y-axis). The Lysholm and IKDC scores, KT-1000 side-to-side difference, pivot shift test and Lachman test results of the knee joints were recorded, and then the differences in knee joint functions between the two groups were analyzed.

RESULTS

84 eligible patients (84 knees) were finally included in this study. Twenty-two and 62 of the patients were categorized in the good and poor position groups, respectively, and the rate of good position was 26.2%. The distribution of bone tunnel was as follows: (x-axis) deep position in 10 patients (12%), normal position in 58 patients (69%), and shallow position in 16 patients (19%); (y-axis) high position in 54 patients (64%), normal position in 26 patients (31%), and low position in 4 patients (5%). 1 year later, the Lysholm and IKDC scores were significantly better in the good position group (P < 0.05), the KT-1000 side to side difference, the pivot shift test and Lachman test results were better in the good position group (P < 0.05).

CONCLUSIONS

The bone tunnels were found to be distributed in and beyond the normal range using the bone landmark method to position the femoral tunnel in the single-bundle anatomical reconstruction of ACL, while the rate of good bone tunnel position was low. The knee joint function scores and stability were lower in patients with poor position of the femoral tunnel.

Elastin is responsible for the rigidity of the ligament under shear and rotational stress: a mathematical simulation study

BACKGROUND

An accurate understanding of the mechanical response of ligaments is important for preventing their damage and rupture. To date, ligament mechanical responses are being primarily evaluated using simulations. However, many mathematical simulations construct models of uniform fibre bundles or sheets using merely collagen fibres and ignore the mechanical properties of other components such as elastin and crosslinkers. Here, we evaluated the effect of elastin-specific mechanical properties and content on the mechanical response of ligaments to stress using a simple mathematical model.

METHODS

Based on multiphoton microscopic images of porcine knee collateral ligaments, we constructed a simple mathematical simulation model that individually includes the mechanical properties of collagen fibres and elastin (fibre model) and compared with another model that considers the ligament as a single sheet (sheet model). We also evaluated the mechanical response of the fibre model as a function of the elastin content, from 0 to 33.5%. Both ends of the ligament were fixed to a bone, and tensile, shear, and rotational stresses were applied to one of the bones to evaluate the magnitude and distribution of the stress applied to the collagen and elastin at each load.

RESULTS

Uniform stress was applied to the entire ligament in the sheet model, whereas in the fibre model, strong stress was applied at the junction between collagen fibres and elastin. Even in the same fibre model, as the elastin content increased from 0 to 14.4%, the maximum stress and displacement applied to the collagen fibres during shear stress decreased by 65% and 89%, respectively. The slope of the stress-strain relationship at 14.4% elastin was 6.5 times greater under shear stress than that of the model with 0% elastin. A positive correlation was found between the stress required to rotate the bones at both ends of the ligament at the same angle and elastin content.

CONCLUSIONS

The fibre model, which includes the mechanical properties of elastin, can provide a more precise evaluation of the stress distribution and mechanical response. Elastin is responsible for ligament rigidity during shear and rotational stress.