Yasutaka Tashiro

The Graft Bending Angle Can Affect Early Graft Healing After Anterior Cruciate Ligament Reconstruction: In Vivo Analysis With 2 Years’ Follow-up

Background: A high graft bending angle (GBA) after anterior cruciate ligament (ACL) reconstruction has been suggested to cause stress on the graft. Nevertheless, evidence about its effect on graft healing in vivo is limited. Hypothesis: The signal intensity on magnetic resonance imaging (MRI) would be higher in the proximal region of the ACL graft, and higher signals would be correlated to a higher GBA. Study Design: Descriptive laboratory study. Methods: Anatomic single-bundle ACL reconstruction was performed on 24 patients (mean age, 20 ± 4 years) using the transportal technique. A quadriceps tendon autograft with a bone plug was harvested. To evaluate graft healing, the signal/noise quotient (SNQ) was measured in 3 regions of interest (ROIs) of the proximal, midsubstance, and distal ACL graft using high-resolution MRI (0.45 × 0.45 × 0.70 mm), with decreased signals suggesting improved healing. Dynamic knee motion was examined during treadmill walking and running to assess the in vivo GBA. The GBA was calculated from the 3-dimensional angle between the graft and femoral tunnel vectors at each motion frame, based on tibiofemoral kinematics determined from dynamic stereo X-ray analysis. Graft healing and GBAs were assessed at 6 and 24 months postoperatively. Repeated-measures analysis of variance was used to compare the SNQ in the 3 ROIs at 2 time points. Pearson correlations were used to analyze the relationship between the SNQ and mean GBA during 0% to 15% of the gait cycle. Results: The SNQ of the ACL graft in the proximal region was significantly higher than in the midsubstance (P = .022) and distal regions (P < .001) at 6 months. The SNQ in the proximal region was highly correlated with the GBA during standing (R = 0.64, P < .001), walking (R = 0.65, P = .002), and running (R = 0.54, P = .015) but not in the other regions. At 24 months, signals in the proximal and midsubstance regions decreased significantly compared with 6 months (P < .001 and P = .008, respectively), with no difference across the graft area. Conclusion: The signal intensity was highest in the proximal region and lowest in the distal region of the reconstructed graft at 6 months postoperatively. A steep GBA was significantly correlated with high signal intensities of the proximal graft in this early period. A steep GBA may negatively affect proximal graft healing after ACL reconstruction.

Steeper posterior tibial slope correlates with greater tibial tunnel widening after anterior cruciate ligament reconstruction

PurposeTo investigate the correlation between posterior tibial slope (PTS) and tibial tunnel widening after anterior cruciate ligament reconstruction (ACL-R).MethodsTwenty-five patients underwent anatomic single-bundle ACL-R using quadriceps tendon autograft. Six months after surgery, each patient underwent high-resolution computed tomography (CT). Tibial tunnel aperture location was evaluated using a grid method. Medial and lateral PTS (°) was measured based on a previously described method. To evaluate tibial tunnel widening, cross-sectional area (CSA) of the tibial tunnel beneath the aperture was measured using CT axial slice. Nominal elliptical area was calculated using the diameter of a dilator during the surgery and the angle between the axial slice and the tunnel axis. Percentage of tunnel widening (%) was determined by dividing the CSA by the nominal area. Pearson correlation coefficient was used to explore the association between medial/lateral PTS and tibial tunnel widening (P < 0.05).ResultsLocation of tibial tunnel aperture was 29.8 ± 6.3% in anterior–posterior direction, and 45.7 ± 2.1% in medial–lateral direction. Medial and lateral PTS were 3.7° ± 2.5° and 4.9° ± 2.4° respectively. Tibial tunnel widening was 97.2 ± 20.3%. Tibial tunnel widening was correlated with medial PTS (r = 0.558, P = 0.004) and lateral PTS (r = 0.431, P = 0.031).ConclusionSteeper medial and lateral PTS correlated with greater tibial tunnel widening. The clinical relevance is that surgeons should be aware that PTS may affect tibial tunnel widening after ACL-R. Thus, subjects with steeper PTS may need to be more carefully followed to see if there is greater tibial tunnel widening, which might be important especially in revision ACL-R.Level of evidenceIII.

Patient-reported outcome measures following anterior cruciate ligament reconstruction are not related to dynamic knee extension angle

Objectives Controversy still exists on whether knee hyperextension affects the outcome following anterior cruciate ligament reconstruction (ACL-R). Therefore, the purpose of the present study was to determine if maximum knee extension angle of ACL-R knees and contralateral uninjured knees during walking is related to the clinical outcome following ACL-R. It was hypothesised that maximum knee extension angle would not be significantly correlated with patient-reported outcome measures (PROMs) following ACL-R. Methods Forty-two patients (age at surgery: 23±9 years, 23 male and 19 female) underwent unilateral ACL-R. Twenty-four months after surgery, subjects performed level walking on a treadmill while biplane radiographs were acquired at 100 Hz. Three-dimensional tibiofemoral motion was determined using a validated model-based tracking process. Tibiofemoral rotations were calculated from foot strike through early stance. The primary kinematic outcome measure was maximum knee extension angle of ACL-R and contralateral uninjured knees during walking, with positive values indicating hyperextension. The side-to-side difference (SSD) in maximum knee extension angle was calculated by subtracting the angle of the contralateral uninjured knee from that of the ACL reconstructed knee. PROMs (International Knee Documentation Committee Subjective Knee Form, Knee Injury and Osteoarthritis Score and Marx Activity Rating Scale) were obtained at 24 months after surgery. Correlations between PROMs and maximum dynamic knee extension angle in ACL-R and contralateral knee were evaluated (P<0.05). Results Maximum knee extension angle during walking was 2.3±4.5° in ACL-R knees and 4.3±4.2° in contralateral uninjured knees at 24 months after surgery, indicating hyperextension during walking on average. SSD in maximum knee extension angle was −2.0±3.7°. No significant correlation was observed between maximum knee extension angle and the PROMs. Conclusion Maximum knee extension angle during walking was not significantly correlated with PROMs, suggesting that clinically, physiologic knee hyperextension can be restored after ACL-R and not adversely affect PROMs. Level of evidence Level III.

Anterolateral rotatory instability in vivo correlates tunnel position after anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft

AIM To quantitatively assess rotatory and anterior-posterior instability in vivo after anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BTB) autografts, and to clarify the influence of tunnel positions on the knee stability. METHODS Single-bundle ACL reconstruction with BTB autograft was performed on 50 patients with a mean age of 28 years using the trans-tibial (TT) (n = 20) and trans-portal (TP) (n = 30) techniques. Femoral and tibial tunnel positions were identified from the high-resolution 3D-CT bone models two weeks after surgery. Anterolateral rotatory translation was examined using a Slocum anterolateral rotatory instability test in open magnetic resonance imaging (MRI) 1.0-1.5 years after surgery, by measuring anterior tibial translation at the medial and lateral compartments on its sagittal images. Anterior-posterior stability was evaluated with a Kneelax3 arthrometer. RESULTS A total of 40 patients (80%) were finally followed up. Femoral tunnel positions were shallower (P < 0.01) and higher (P < 0.001), and tibial tunnel positions were more posterior (P < 0.05) in the TT group compared with the TP group. Anterolateral rotatory translations in reconstructed knees were significantly correlated with the shallow femoral tunnel positions (R = 0.42, P < 0.01), and the rotatory translations were greater in the TT group (3.2 ± 1.6 mm) than in the TP group (2.0 ± 1.8 mm) (P < 0.05). Side-to-side differences of Kneelax3 arthrometer were 1.5 ± 1.3 mm in the TT, and 1.7 ± 1.6 mm in the TP group (N.S.). Lysholm scores, KOOS subscales and re-injury rate showed no difference between the two groups. CONCLUSION Anterolateral rotatory instability significantly correlated shallow femoral tunnel positions after ACL reconstruction using BTB autografts. Clinical outcomes, rotatory and anterior-posterior stability were overall satisfactory in both techniques, but the TT technique located femoral tunnels in shallower and higher positions, and tibial tunnels in more posterior positions than the TP technique, thus increased the anterolateral rotation. Anatomic ACL reconstruction with BTB autografts may restore knee function and stability.

Does Knee Hyperextension Affect Dynamic In Vivo Kinematics and Clinical Outcomes after Anterior Cruciate Ligament Reconstruction

Objectives: There is no consensus on whether knee hyperextension affects postoperative outcome after anterior cruciate ligament reconstruction (ACL-R). A limitation of previous studies is that they evaluated only static joint laxity. The purpose of this study was to evaluate the effect of dynamic hyperextension on postoperative dynamic in vivo kinematics and clinical outcomes. It was hypothesized that patients with a high degree of knee hyperextension in the contralateral normal knee would have larger ranges of anterior translation and internal-external rotation of the ACL reconstructed knee during dynamic activities, and lower patient-reported outcome (PRO) subjective scores compared to the patients who have less contralateral knee hyperextension. Methods: Forty-one patients (22±8 y.o., 27 male / 14 female) underwent unilateral ACL-R. According to the maximum extension angle of the contralateral normal knee during gait using dynamic stereo X-ray (DSX) images, subjects were divided into 2 groups at the median value (4.7°): Hyperextension group (n = 21, knee extension: 7.8±2.2°), and Normal extension group (n = 20, knee extension: 2.4±2.0°). Six and twenty-four months after ACL-R, subjects performed level gait and downhill running on a treadmill while DSX images were acquired at 100Hz (gait) or 150Hz (running). Tibiofemoral motion was determined from DSX images using a previously validated model-based tracking process, and tibiofemoral translations/rotations from initial contact to initial loading (gait cycle: 0-10%) were calculated. The side-to-side differences (SSD) of range of tibiofemoral motions at 6 and 24 months after surgery were calculated. KT-1000 measurements and PRO (IKDC Subjective Knee Form and KOOS scores) at 24 months after surgery were also evaluated. Results of kinematics were analyzed using 2-way repeated-measures ANOVA, and the SSD of kinematics, KT-1000 measurements and PROs were analyzed using student t-test (P < 0.05). Results: The ACL reconstructed knee was significantly more extended in Hyperextension group than in Normal extension group at 6 months (3.9±4.7° vs -0.5±5.3°, P = 0.007) and 24 months (4.8±3.2° vs 0.5±4.6°, P = 0.001) after surgery. Regarding the kinematics of affected knees, there were no significant differences in anterior translation or internal rotation between the 2 groups at 6 months and 24 months after surgery, although there were trends of increased anterior translation and internal rotation over time in both groups (Figure 1). Even in SSD, there was no significant difference between 2 groups. There were also no significant differences in terms of KT-1000 measurements and PRO. Conclusion: This is the first study to assess the effect of dynamic knee hyperextension on in vivo kinematics after ACL reconstruction. The main findings of this study were that there were no significant differences of dynamic in vivo kinematics and clinical outcomes between Hyperextension and Normal extension groups, contrary to the hypothesis. Although knee hyperextension is believed to be a risk factor for poor outcome, the results of this study do not show significant influence of knee hyperextension on the functional kinematics and clinical outcomes after ACL-R. Figure 1. Mean knee kinematics during downhill running in affected knees. There was no significant difference in anterior tibial translation (A) or internal rotation (B) between two groups at both six and twenty-four months after surgery (n.s.: not significant).

Posterior Tibial Subchondral Bone and Meniscal Slope Correlate with In Vivo Internal Tibial Rotation

Objectives: Increased posterior tibial slope (PTS) results in an anteriorly directed force on the knee and is associated with a high-grade pivot shift. However, all published articles on this topic draw conclusions based on static measurements, while no study investigated the role of the PTS and posterior meniscal slope (PMS) on in vivo knee kinematics. Therefore, the objective of this study was to correlate the lateral and medial PTS and PMS with in vivo anterior tibial translation (ATT) and internal tibial rotation during level walking and downhill running on both the ACL reconstructed and healthy knees six months after index surgery. It was hypothesized that an increased lateral PTS and lateral PMS are associated with increased ATT and internal tibial rotation. Methods: Forty-two individuals (twenty-six males; mean age 21.2 ± 6.9 years) who underwent unilateral ACL reconstruction were included in this study. Morphologic parameters were measured on 3T magnetic resonance images (MRI) using the 3D DESS sequence on the ACL reconstructed and healthy contralateral knee. Lateral and medial PTS and PMS were measured according to the method described by Hudek et al. Briefly, the tibial shaft axis was determined by connecting the centroids of two circles fitting the tibial shaft on the central sagittal MRI slice. The PTS and PMS were determined by the angle between the tibial shaft axis and the line connecting the two most proximal anterior and posterior subchondral bone and meniscal points in the center of each joint compartment. Three-dimensional in vivo kinematics data were acquired using dynamic stereo X-ray during level walking (1.3 m/s) at 100 Hz and downhill running (3.0 m/s, 10° slope) at 150 Hz, six months after unilateral ACL reconstruction. Correlations between bone morphology and dynamic kinematics were evaluated using Spearman´s Rho. The significance level was set at p < .05. Results: In ACL intact knees, ATT did not correlate significantly with PTS and PMS (all p ≥ .264; Table 1). Internal tibial rotation was associated with higher posterior slopes in the lateral knee compartment. Larger differences between lateral and medial PTS and PMS were significantly correlated with increased internal tibial rotation (all ≤ .010), while medial PTS and PMS did not correlate with tibial rotation (all p ≥ .457). In ACL reconstructed knees ATT was positively correlated with an increased lateral PMS during level walking (p = .016). ACL reconstructed knees were found to have greater internal tibial rotation with larger lateral compartment slopes as well as with larger lateral-medial differences for PTS and PMS during level walking (all p ≤ .035). Conclusion: The most important finding of the present study is that both lateral PTS and PMS are related to dynamic, functional in vivo kinematics, especially internal tibial rotation. ATT was only associated with lateral PMS in ACL reconstructed knees. Taking into account the results of the present study, the lateral PTS and PMS and the slope differences between the lateral and medial joint compartment may contribute to internal rotation when an ACL injury occurs. However, the analyzed movement was a straight-ahead walk and run without any cutting or pivoting maneuvers commonly related to ACL tears. In such motion patterns, the correlations may be even stronger compared to the results of this study. However, this novel study is the first to assess the relationship between articulating surface morphology and in vivo functional movement.