Tom Gale

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.

The Effects of Anterior Cruciate Ligament Deficiency on the Meniscus and Articular Cartilage A Novel Dynamic In Vitro Pilot Study

Background: Anterior cruciate ligament (ACL) injury increases the risk of meniscus and articular cartilage damage, but the causes are not well understood. Previous in vitro studies were static, required extensive knee dissection, and likely altered meniscal and cartilage contact due to the insertion of pressure sensing devices. Hypothesis: ACL deficiency will lead to increased translation of the lateral meniscus and increased deformation of the medial meniscus as well as alter cartilage contact location, strain, and area. Study Design: Descriptive laboratory study. Methods: With minimally invasive techniques, six 1.0-mm tantalum beads were implanted into the medial and lateral menisci of 6 fresh-frozen cadaveric knees. Dynamic stereo x-rays (DSXs) were obtained during dynamic knee flexion (from 15° to 60°, simulating a standing squat) with a 46-kg load in intact and ACL-deficient states. Knee kinematics, meniscal movement and deformation, and cartilage contact were compared by novel imaging coregistration. Results: During dynamic knee flexion from 15° to 60°, the tibia translated 2.6 mm (P = .05) more anteriorly, with 2.3° more internal rotation (P = .04) with ACL deficiency. The medial and lateral menisci, respectively, translated posteriorly an additional 0.7 mm (P = .05) and 1.0 mm (P = .03). Medial and lateral compartment cartilage contact location moved posteriorly (2.0 mm [P = .05] and 2.0 mm [P = .04], respectively). Conclusion: The lateral meniscus showed greater translation with ACL deficiency compared with the medial meniscus, which may explain the greater incidences of acute lateral meniscus tears and chronic medial meniscus tears. Furthermore, cartilage contact location moved further posteriorly than that of the meniscus in both compartments, possibly imparting more meniscal stresses that may lead to early degeneration. This new, minimally invasive, dynamic in vitro model allows the study of meniscus function and cartilage contact and can be applied to evaluate different pathologies and surgical techniques. Clinical Relevance: This novel model illustrates that ACL injury may lead to significant meniscus and cartilage abnormalities acutely, and these parameters are dynamically measurable while maintaining native anatomy.

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.

Anterior Cruciate Ligament Reconstruction Affects Tibiofemoral Joint Congruency During Dynamic Functional Movement

Background: Anterior cruciate ligament reconstruction (ACLR) has been shown to alter kinematics, which may influence dynamic tibiofemoral joint congruency (a measure of how well the bone surfaces fit together). This may lead to abnormal loading of cartilage and joint degeneration. However, joint congruency after ACLR has never been investigated. Hypotheses: The ACLR knee will be more congruent than the contralateral uninjured knee, and dynamic congruency will increase over time after ACLR. Side-to-side differences (SSD) in dynamic congruency will be related to cartilage contact location/area and subchondral bone curvatures. Study Design: Descriptive laboratory study. Methods: The authors examined 43 patients who underwent unilateral ACLR. At 6 months and 24 months after ACLR, patients performed downhill running on a treadmill while synchronized biplane radiographs were acquired at 150 images per second. Dynamic tibiofemoral kinematic values were determined by use of a validated volumetric model-based tracking process that matched patient-specific bone models, obtained from computed tomography, to biplane radiographs. Patient-specific cartilage models, obtained from magnetic resonance imaging, were registered to tracked bone models and used to calculate dynamic cartilage contact regions. Principle curvatures of the subchondral bone surfaces under each cartilage contact area were calculated to determine joint congruency. Repeated-measures analysis of variance was used to test the differences. Multiple linear regression was used to identify associations between SSD in congruency index, cartilage contact area, contact location, and global curvatures of femoral or tibial subchondral bone. Results: Lateral compartment congruency in the ACLR knee was greater than in the contralateral knee (P < .001 at 6 months and P = .010 at 24 months). From 6 to 24 months after surgery, dynamic congruency decreased in the medial compartment (P = .002) and increased in the lateral compartment (P = .007) in the ACLR knee. In the lateral compartment, SSD in joint congruency was related to contact location and femur global curvature, and in the medial compartment, SSD in joint congruency was related to contact area. Conclusion: ACLR appears to affect dynamic joint congruency. SSD in joint congruency was associated with changes in contact location, contact area, and femoral bony curvature. Clinical Relevance: Alterations in tibiofemoral contact location, contact area, and bone shape affect dynamic joint congruency, potentially contributing to long-term degeneration after ACLR.

Intervertebral kinematics of the cervical spine before, during, and after high-velocity low-amplitude manipulation

BACKGROUND CONTEXT Neck pain is one of the most commonly reported symptoms in primary care settings, and a major contributor to health-care costs. Cervical manipulation is a common and clinically effective intervention for neck pain. However, the in vivo biomechanics of manipulation are unknown due to previous challenges with accurately measuring intervertebral kinematics in vivo during the manipulation. PURPOSE The objectives were to characterize manual forces and facet joint gapping during cervical spine manipulation and to assess changes in clinical and functional outcomes after manipulation. It was hypothesized that patient-reported pain would decrease and intervertebral range of motion (ROM) would increase after manipulation. STUDY DESIGN/SETTING Laboratory-based prospective observational study. PATIENT SAMPLE 12 patients with acute mechanical neck pain (4 men and 8 women; average age 40 ± 15 years). OUTCOME MEASURES Amount and rate of cervical facet joint gapping during manipulation, amount and rate of force applied during manipulation, change in active intervertebral ROM from before to after manipulation, and numeric pain rating scale (NPRS) to measure change in pain after manipulation. METHODS Initially, all participants completed a NPRS (0-10). Participants then performed full ROM flexion-extension, rotation, and lateral bending while seated within a custom biplane radiography system. Synchronized biplane radiographs were collected at 30 images/s for 3 seconds during each movement trial. Next, synchronized, 2.0-milliseconds duration pulsed biplane radiographs were collected at 160 images/s for 0.8 seconds during the manipulation. The manipulation was performed by a licensed chiropractor using an articular pillar push technique. For the final five participants, two pressure sensors placed on the thumb of the chiropractor (Novel pliance system) recorded pressure at 160 Hz. After manipulation, all participants repeated the full ROM movement testing and once again completed the NPRS. A validated volumetric model-based tracking process that matched subject-specific bone models (from computed tomography) to the biplane radiographs was used to track bone motion with submillimeter accuracy. Facet joint gapping was calculated as the average distance between adjacent articular facet surfaces. Pre- to postmanipulation changes were assessed using the Wilcoxon signed-rank test. RESULTS The facet gap increased 0.9 ± 0.40 mm during manipulation. The average rate of facet gapping was 6.2 ± 3.9 mm/s. The peak force and rate of force application during manipulation were 65 ± 4 N and 440 ± 58 N/s. Pain score improved from 3.7 ± 1.2 before manipulation to 2.0 ± 1.4 after manipulation (p <. 001). Intervertebral ROM increased after manipulation by 1.2° (p = .006), 2.1° (p = .01), and 3.9° (p = .003) at the C4/C5, C5/C6, and C6/C7 motion segments, respectively, during flexion-extension; by 1.5° (p = .028), 1.9° (p = .005), and 1.3° (p = .050) at the C3/C4, C4/C5, and C5/C6 motion segments, respectively, during rotation; and by 1.3° (p = .034) and 1.1° (p = .050) at the C4/C5 and C5/C6 motion segments, respectively, during lateral bending. Global head ROM relative to the torso increased after manipulation by 8º (p = .023), 10º (p = .002), and 13º (p = .019) during lateral bending, axial rotation and flexion-extension, respectively, after manipulation. CONCLUSIONS This study is the first to measure facet gapping during cervical manipulation on live humans. The results demonstrate that target and adjacent motion segments undergo facet joint gapping during manipulation and that intervertebral ROM is increased in all three planes of motion after manipulation. The results suggest that clinical and functional improvement after manipulation may occur as a result of small increases in intervertebral ROM across multiple motion segments. This study demonstrates the feasibility of characterizing in real time the manual inputs and biological responses that comprise cervical manipulation, including clinician-applied force, facet gapping, and increased intervertebral ROM. This provides a basis for future clinical trials to identify the mechanisms behind manipulation and to optimize the mechanical factors that reliably and sufficiently impact the key mechanisms behind manipulation.

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.

Integrating Multi-Modality Imaging and Biodynamic Measurements for Studying Neck Biomechanics During Sustained-Till-Exhaustion Neck Exertions

Neck musculoskeletal disorders have been associated with various occupational tasks, in particular tasks that require non-neutral sustained exertions. To gain a clear understanding of the neck biomechanics during such exertions, we have recently initiated an unprecedented integration of multi-modality state-of-the-art measurement procedures including dynamic radiographic imaging, surface-based motion capture, electromyography, computed tomography and magnetic resonance imaging. This paper describes an overview of our systematic, integrative efforts of in vivo biodynamic measurements during sustained-till- exhaustion neck exertions and multi-modality imaging data, and how such an integrated database can be used to construct subject-specific neck musculoskeletal models. A complete dataset of one participant is presented to illustrate the acquired data. In the next phase, subject-specific ‘what-if’ computer simulations will be implemented to understand the mechano-physiological effects of sustained-till-exhaustion neck exertions for different work scenarios and worker characteristics in order to derive effective injury prevention and intervention strategies.

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.