Injured Anterior Cruciate Ligament Research Articles

Braided biomimetic PCL grafts for anterior cruciate ligament repair and regeneration

Anterior cruciate ligament (ACL) is a knee joint stabilizer with a limited regeneration capacity mainly because of low cellular content. State-of-the-art procedures are unable to restore the functions of the tissue as demonstrated by limited success rates. Regenerative engineering can offer a solution for restoring the functions of torn/ruptured ligaments provided that biomimetic grafts are available as grafts/scaffolds. However, a model construct to test behavior of cells to better understand the healing mechanism of ACL is still missing. This study, firstly, aimed at creating an injured rabbit ACL model. Then, the injured and healthy ACL tissues were characterized in terms of alignment and diameter distributions of collagen fibrils. Next, polycaprolactone (PCL) grafts were prepared from braided electrospun meshes and were characterized in terms of alignment and diameter distributions of fibers. Finally, biomechanical properties of ACL tissue and mechanical properties of PCL grafts were determined and compared. Findings demonstrated that distributions of the fiber diameters of PCL electrospun grafts were similar to diameter distribution of collagens of healthy and injured rabbit ACL. The novelty of this study relies on the determination of the diameter distribution of collagens of healthy and injured rabbit ACL tissues, and fabrication of PCL grafts with diameter distributions similar to that seen in healthy and injured ACLs. This study is significant because it addresses a worldwide clinical problem associated with millions of patients. The fibrous biomimetic graft designed in this study is different from the traditional grafts that exhibit unimodal distribution, and it is expected to have a significant contribution to ACL regeneration efforts.

Left peroneal paresis in a young female basketball player after anterior cruciate ligament reconstruction of the right knee

There are various reasons for the injury to the peroneal nerve but the most common cause is compression anywhere along its route, from the origin to the distal branches, usually at the knee level. At the knee level, compression on the fibular level within the course of the peroneal nerve and anatomical and pathological is the site where the peroneal nerve is usually affected. Iatrogenic injuries after surgical interventions to the knee, metabolic, or toxic causes are also common. We present the case of a young female basketball player who underwent a surgical procedure for the injured anterior cruciate ligament of the right knee and during the rehabilitation process, peroneal paresis of a left leg occurred.

The Risk Factors Affected Upon Non-Contact ACL Injury in Gymnastics, Swimming and Basketball Collegiate Student Female Players

The purpose of the present study was to determine of the risk factors affected upon non-contact ACL injury in Gymnastics, Swimming and basketball collegiate student female players. If an athlete injured anterior cruciate ligament the most important thing is to identify factors that affect the injury. However, growing research implicates hormonal, anatomical, environmental and neuromuscular factors that may predispose athletes to these injuries. For this research selected 510 athletes for assess ACL injury factors by two different methods (A) Questionnaire and (B) Interview that information collected among athletes who were play Gymnastics, Swimming and basketball. Our results indicate 61.4% of ACL injury occurred in practice time and 38.6% of ACL injury was during competition. Also, our finding showed that 69% mechanism of injury was non-contact, 4.7% via accident and 26.3% with unknown reason. Furthermore, dynamic alignment at the time of the injury included: Knee-in & Toe- out 44%, Knee-out & Toe-in 22.5 and Hyperextension 11.1%. The ACL prevents the femur from moving forward during weight bearing. It also helps to prevent rotation of the joint. Injury of the ACL most often occurs when an athlete is pivoting, decelerating suddenly or landing from a jump. The injury can also be caused by another player falling across the knee. ACL injuries are, probably, the most common devastating knee ligament injuries amongst sports persons. Usually these injuries are isolated, mainly in non-contact sports, but many often are a part of more complex ligamentous injuries. They occur more often in contact sports, such as basketball. In conclusion, our study produced strong evidence in support of a significant some factors influencing of ACL injury in Gymnastics, Swimming and basketball collegiate student female players.

Muscle dynamics analysis by clustered categories during jogging in patients with anterior cruciate ligament deficiency

BackgroundPatients with anterior cruciate ligament (ACL) deficiency (ACLD) tend to have altered lower extremity dynamics. Little is known about the changes in dynamic function and activation during jogging in patients with ACLD.MethodsTwenty patients with an injured ACL before ACL reconstruction (ACLD group) and nine healthy male volunteers (control group) were recruited. Each volunteer repeated the jogging experiment five times. Based on the experimental data measured, a musculoskeletal multibody dynamics model was employed to simulate the tibiofemoral joint dynamics during jogging. Eighteen muscles were used for analysis. The obtained dynamics data were used for clustering and curve difference analysis.ResultsThe 18 muscles studied were divided into 3 categories. All the quadriceps, the soleus, the gastrocnemius, and the popliteus were classified as label 1. All the hamstrings were classified as label 2, and the sartorius muscles were classified as label 3. Among them, the classification of the short head of the biceps femoris was significantly different between the two groups (P < 0.001). The force curves of all 18 muscles and the between-group differences were studied according to clustered categories. Most muscle force in label 1 was approaching zero in the terminal stance phase, which was significantly lower than that in the control group (P < 0.05). The muscle force in label 2 had areas with significant differences in the stance phase. Muscle force in label 3 was significantly lower than that in the control group in the pre-swing phase.ConclusionsThis study showed that there are various changes of muscle function and activation in patients with ACLD. Through clustering and curve analysis, the joint reactions and changes of different muscle forces in the gait cycle between the ACLD and control groups could be further clarified.

Ligament Healing After Anterior Cruciate Ligament Rupture: An Important New Patient Pathway?

Recent studies have shown satisfactory functional results after spontaneous healing of a ruptured anterior cruciate ligament (ACL). However, current literature on this topic may exclude important parting selection, outcome measures, and long-term results. Rehabilitation protocols applied in those studies, as well as objective assessments appear far from the usual gold standard after ACL reconstruction. Ideally, outcomes measures should be based on the same testing procedures that are recommended to clear an athlete to return to sport following ACL reconstruction. There is still a lot to understand in how an injured ACL may heal, and therefore ACL injury management should be individualized to each patient and carefully discussed.

Construction and validation of a functional diagnostic score in anterior cruciate ligament ruptures of the knee in the immediate post-traumatic period. Preliminary results of a multicenter prospective study

IntroductionKnee ligament injuries are frequent and their number is constantly increasing with the development of sports activities. Dynamic knee maneuvers usually make it possible to diagnose anterior cruciate ligament (ACL) injuries but they remain difficult to perform in the early post-traumatic phase. This leads to the almost systematic use of MRI scans, many of which turn out to be superfluous. The aim of this study was to construct a screening score based solely on history-taking, in order to help diagnose ACL injuries, and to define thresholds that could help inform recommendations for MRI usage. The hypothesis was that this score could distinguish a population of patients with a ruptured ACL from a population of patients with other knee injuries. Material and methodsThis prospective multicenter study included 166 patients. Patients were included if they were between 18 and 55 years of age, with knee trauma that had occurred in the last 10 days, and without a bone fracture on standard radiographs. They were excluded if the trauma required immediate surgical management and if they had a history of knee trauma. The screening score was completed by the physician. The score included the following items: assessment of pain, immediate post-traumatic functional impairment, notion of a “pop”, feeling of instability and presence of a swelling. An MRI was systematically performed and the patient consulted a referring physician to compare the initial score with the diagnosis. ResultsEighty-six patients had an injured ACL and 80 had a healthy ACL. Two thresholds could be identified. For a score lower than 4, the risk of an ACL injury was low with a sensitivity of 96% and a negative predictive value of 87%. For a score above 8, the ACL injury was highly probable with a specificity of 88% and a positive predictive value of 83%. Discussion/conclusionThe score was able to distinguish a population of patients with a ruptured ACL from a population of patients with other knee injuries. These preliminary results confirm that the selected items are relevant and that the score can help improve the diagnostic orientation of patients with recent knee trauma. Increasing the sample size in combination with an analysis of influencing factors will determine whether the performance of this score can be refined. Level of evidenceII prospective multicenter study.

Anterior cruciate ligament (ACL) injury: correlation with MRI morphometry

BackgroundThis study aims to investigate the association between bony morphological features and ACL injury and to identify potential risk factors for the identification and prevention of ACL injuries. The study used knee MRIs to examine the distal femoral and proximal tibia morphology of 500 patients aged 19–50, including 250 cases with an injured ACL and 250 controls with a non-injured ACL. Previous literature has shown that ACL injuries are a common occurrence in sports and can have serious long-term consequences. Several risk factors have been identified, including anatomical variations in the bony structures of the knee. However, the relationship between bony morphology and ACL injury is not well understood, and there is a need to investigate the potential role of these factors in the identification and prevention of ACL injuries. This study was necessary because of the high incidence of ACL injuries and the potential long-term consequences, such as osteoarthritis, associated with this injury. By identifying potential risk factors, such as bony morphological features, it may be possible to develop targeted prevention strategies to reduce the incidence of ACL injuries. The study also adds to the existing literature by providing new insights into the relationship between bony morphology and ACL injury, and by identifying specific parameters that can be used to predict ACL injury. ResultsThere was a significant difference in bony morphology between ACL-injured and non-injured patients. The most convincing parameters of femur and tibia were notch width index (NWI), medial tibial plateau depth (MTPD), and lateral tibial plateau slope (LTPS). A significantly smaller intercondylar notch was seen in the injured patients (mean 17.25 mm) than in controls (mean 18.41 mm) (p < 0.001, unpaired t test). The findings indicate that among all the features assessed, the medial tibial plateau depth (MTPD) stands out as the most statistically significant with an odds ratio of 2.4, and it demonstrates a substantial association.ConclusionsACL-injured patients have a narrower NWI, shallower MTPD, and steeper LTPS, which appear to be associated with ACL injury. Identifying the cut-off values for these parameters can help predict ACL injury.

Valid and reliable diagnostic performance of dual-energy CT in anterior cruciate ligament rupture

ObjectivesTo determine whether dual-energy CT (DECT) can be used to accurately and reliably detect anterior cruciate ligament (ACL) rupture.Materials and methodsParticipants with unilateral ACL rupture were prospectively enrolled, and the bilateral knees were scanned by DECT. A tissue-specific mapping algorithm was applied to improve the visualization of the ACLs. The 80-keV CT value, mixed-keV CT value, electron density (Rho), and effective atomic number (Zeff) were measured to quantitatively differentiate torn ACLs from normal ACLs. MRI and arthroscopy served as the reference standards.ResultsFifty-one participants (mean age, 27.0 ± 8.7 years; 31 men) were enrolled. Intact and torn ACLs were explicitly differentiated on color-coded DECT images. The 80-keV CT value, mixed-keV CT value, and Rho were significantly lower for the torn ACLs than for the intact ACLs (p < 0.001). The optimal cutoff values were an 80-keV CT value of 61.8 HU, a mixed-keV CT value of 60.9 HU, and a Rho of 51.8 HU, with AUCs of 98.0% (95% CI: 97.0–98.9%), 99.2% (95% CI: 98.6–99.7%), and 99.8% (95% CI: 99.6–100.0%), respectively. Overall, DECT had almost perfect reliability and validity in detecting ACL integrity (sensitivity = 97.1% [95% CI: 88.1–99.8%]; specificity = 98.0% [95% CI: 89.5–99.9%]; PPV = 98.0% [95% CI: 93.0–99.8%]; NPV = 97.1% [95% CI: 91.7–99.4%]; accuracy = 97.5% [95% CI: 94.3–99.2%]). There was no evidence of a difference between MRI and DECT in the diagnostic performance (p > 0.99).ConclusionDECT has excellent diagnostic accuracy and reliability in qualitatively and quantitatively diagnosing ACL rupture.Clinical relevance statementDECT could validly and reliably diagnose ACL rupture using both qualitative and quantitative methods, which may become a promising substitute for MRI to evaluate the integrity of injured ACLs and the maturity of postoperative ACL autografts.Key Points• On color-coded DECT images, an uncolored ACL was a reliable sign for qualitatively diagnosing ACL rupture.• The 80-keV CT value, mixed-keV CT value, and Rho were significantly lower for the torn ACLs than for the intact ACLs, which contributed to the quantitative diagnosis of ACL rupture.• DECT had an almost perfect diagnostic performance for ACL rupture, and diagnostic capability was comparable between MRI and DECT.

The use of slice encoding for metal artifact correction (SEMAC) sequencing improves the diagnostic evaluation of graft integrity following anterior cruciate ligament reconstruction

ObjectivesTo determine whether magnetic resonance imaging (MRI) with metal artifact reduction sequencing is superior to conventional knee MRI in the evaluation of an injured anterior cruciate ligament (ACL) graft, where visualisation on conventional MRI can be limited by the metal artifact from fixation devices. MethodsEighteen patients underwent conventional MRI sequence (proton density fat saturated [PDFS]) and two types of metal artifact reduction sequencing MRI (WARP, slice encoding for metal artifact correction (SEMAC); Siemens) following a secondary injury to their ACL reconstructed knee. Six raters with experience in knee MRI evaluation reviewed sagittal PDFS, WARP, and SEMAC sequences, providing semi-quantitative grades for visualisation and diagnostic confidence assessing the ACL, posterior cruciate ligament , menisci, tibial and femoral tunnel margins, and articular cartilage. Intra-class correlation coefficients for inter-rater reliability were evaluated. The 6-rater mean scores for the visualisation and diagnostic confidence derived from each sequence were compared using the Friedman test for multiple paired samples. ResultsNo statistically significant difference in the ACL visualisation among the sequences was found (p ​= ​0.193). Further, a subgroup analysis was performed in cases evaluated as “moderately blurry” or “indistinct ACL visualisation” on PDFS (58% of cases). SEMAC significantly improved diagnostic confidence in ACL visualisation (p ​= ​0.041) and ACL graft rupture (p ​= ​0.044) compared to PDFS.There was no statistically significant difference in the inter-observer reliability between sequences. The WARP sequence added 2.84 ​± ​0.69 ​min, while SEMAC added 2.95 ​± ​0.40 ​min to the standard knee MRI scan time. Conclusionuse of the SEMAC metal reduction sequence significantly improved diagnostic accuracy and confidence in the detection of ACL graft rupture in cases where the ACL was moderately blurry or indistinct on the PDFS sequence. This sequence should be considered as an adjunct to conventional PDFS in cases where graft visualisation is limited by the metal artifact from fixation devices. Level of evidenceIII.

Collagen Fibril Diameter Distribution of Sheep Anterior Cruciate Ligament.

The anterior cruciate ligament (ACL) tissue is a soft tissue connecting the femur and tibia at the knee joint and demonstrates a limited capacity for self-regeneration due to its low vascularity. The currently available clinical procedures are unable to fully restore damaged ACL tissue, and tissue engineering can offer options with a potential of restoring the torn/ruptured ACL by using biomimetic constructs that are similar to native tissue in terms of structure, composition, and functions. However, a model substrate to understand how the ACL cells regenerate the injured tissue is still not available. In this study, it is hypothesized that the nanofiber-based model substrate with bimodal and unimodal fiber diameter distributions will mimic the diameter distribution of collagen fibrils seen in healthy and injured sheep ACL, respectively. The aims were to (i) create an ACL injury in a sheep ACL by applying extensional force to rupture the healthy ACL tissue, (ii) measure the collagen fibril diameter distributions of healthy and injured ACL, (iii) fabricate polycaprolactone (PCL) nanofiber-based model constructs using electrospinning with diameter distributions similar to healthy and injured ACL tissue, and (iv) measure mechanical properties of ACL tissue and PCL electrospun constructs. The results showed that the fiber diameter distributions of PCL electrospun constructs and those of the healthy and injured ACL tissues were similar. The novelty in this investigation is that the collagen fibril diameter distribution of healthy and injured sheep ACL tissues was reported for the first time. The study is significant because it aims to create a model construct to solve an important orthopedic-related clinical problem affecting millions of people globally. The model construct fabricated in this work is expected to have an important impact on ACL regeneration efforts.

Bone Bruise Patterns in Ligamentous Injuries of the Knee With Focus on Anterior Cruciate Ligament.

Introduction After sustaining an anterior cruciate ligament (ACL) injury, the bone bruises seen on magnetic resonance imaging (MRI) could reveal plenty of information regarding the loading mechanisms causing injury to the ACL. The current study was conducted to evaluate the common distribution patterns of bone bruises following an ACL injury and understand the loading mechanisms. Methods The knee MRI sequences of the patients operated arthroscopically for an injured ACL between August 2016 to August 2018 were selected for the study. The distribution pattern of the bone bruises was determined using the sagittal and coronal sections of MRI. The pattern of distribution of the bone bruises was categorized and analyzed by two independent observers. Results Twenty-two patients were found to have bone bruises diagnosed in the MRI scans. The mean age of the patients was 27.8 ± 8.7 years. The pattern of a bone bruises in only the lateral femoral and tibial compartments was the most typical pattern observed in this study. The study pattern has a significant anterior distribution of bone bruises on the outer (lateral) compartment of both the femur and tibia as compared to the inner (medial) compartment (p< .05 and p > .05, respectively). The inter-rater reliability between the two observers by Cronbach's Alpha was 93.2%. Conclusion Having the appropriate information regarding the pattern distribution of bone bruises and the concomitant injuries associated with it furthers our knowledge and helps us understand the loading mechanisms of ACL tears. A combination of coup forces acting on the lateral compartment and the contrecoup varus force on the medial compartment of the knee during the primary pivot-shift injury suggests an an involvement of multiplanar loading patterns at the point of sustaining ACL tear.

Bridge-Enhanced Anterior Cruciate Ligament Repair for Mid-Substance Tear With Concomitant Lateral Meniscus Radial Repair

In recent years, repair of the injured anterior cruciate ligament (ACL) has been subject to a renewed interest as novel arthroscopic techniques have been developed. Specifically, the bridge-enhanced ACL repair is a technique composed of a resorbable protein-based implant combined with autologous blood that is used to bridge the gap between 2 torn edges of a mid-substance ACL tear. This implant is believed to help facilitate healing of a primary suture repair and suture cinch and has since demonstrated noninferiority to ACL reconstruction with autograft at 2-year follow-up. The purpose of this Technical Note is to describe a step-by-step surgical technique of a mid-substance ACL repair using the bridge-enhanced ACL repair system in a case with a concomitant lateral meniscus radial repair

Walking in the Absence of Anterior Cruciate Ligament: The Role of the Quadriceps and Hamstrings

The actual need for surgical reconstruction of an injured anterior cruciate ligament (ACL) is still a matter of debate. The aim of this study was to quantify and analyze the knee kinematics and the ligament force redistribution resulting from the ACL sacrifice and the consequent effects of changing the quadriceps and hamstring activity during walking. A three-dimensional musculoskeletal model was used to simulate the behavior of the knee joint during the gait cycle, in different testing conditions: an ACL-deficient knee, an ACL-deficient knee with hamstrings inactivated and an ACL-deficient knee with quadriceps inactivated. Our results showed that in the ACL-deficient knee, the medial collateral ligament (MCL) was the main passive stabilizer of the anterior translation of the tibia. Furthermore, the compensation effects produced by the hamstrings and quadriceps in the ACL-deficient knee during walking were quantified and analyzed. In the case of ACL sacrifice, reducing the quadriceps activity would allow for relieving all ligaments in general, except for the posterior cruciate ligament, which required more consistent recruitment in the support phase. Meanwhile, hamstring activity was crucial not only to compensate for the absence of ACL in limiting the anterior tibial displacement but also to reduce the risk of MCL injury.

TGF-β1 and Mechanical-Stretch Induction of Lysyl-Oxidase and Matrix-Metalloproteinase Expression in Synovial Fibroblasts Requires NF-κB Pathways

The imbalance in the expression of matrix metalloproteinases (MMPs) and lysyl oxidases (LOXs) in synovial fibroblasts (SFs) caused by mechanical injury and inflammatory response prevents injured anterior cruciate ligaments (ACLs) from self-healing. However, research on the effect of growth factors on SFs on regulating the microenvironment is limited. In this study, mechanical injury and exogenous transform growth factor-β1 (TGF-β1) were employed to mimic a joint-cavity microenvironment with ACL trauma. The function of the NF-κB transcription factor was further studied. The study found that the gene expression of LOXs (except LOXL-1), MMP-1, -2, and -3 in SFs was promoted by the combination of injurious mechanical stretching and TGF-β1 and that the upregulation of MMPs was higher than that of LOXs. In addition, MMP-2 activity induced by the combination of injurious stretch and TGF-β1 was inhibited by NF-κB inhibitors such as Bay11-7082 and Bay11-7085. The findings concluded that the synovium was an important regulator of the knee joint-cavity microenvironment after ACL injury and that the NF-κB pathway mediated the regulation of MMP-2 in SFs via mechanical factors and TGF-β1.

The influence of ruptured scar pattern of human anterior cruciate ligament remnant tissue on tendon-bone healing in vivo.

The purpose of this study was to determine whether the transplantation of human cells from a non-reattached injured anterior cruciate ligament (ACL) remnant could enhance tendon-bone healing. Human ACL remnant tissue was classified into two groups based on the morphologic pattern as per Crain's classification: (1) non-reattachment group (Crain Ⅳ) and (2) reattachment group (Crain Ⅰ-Ⅲ). Seventy-five 10-week-old immunodeficient rats underwent ACL reconstruction followed by intracapsular administration of one of the following: (1) ACL-derived cells from the non-reattached remnant (non-reattachment group) (n = 5), (2) ACL-derived cells from the reattached tissue (reattachment group) (n = 5), or (3) phosphate-buffered saline(PBS) only (PBS group) (n = 5). Histological (Weeks 2, 4, and 8), immunohistochemical (Week 2), radiographic (Weeks 0, 2, 4, and 8), and biomechanical (Week 8) assessments were performed. Histological evaluation showed high and early healing, induction of endochondral ossification-like integration, and mature bone ingrowth at Week 4 in the non-reattachment group. Microcomputed tomography at Week 4 showed that the tibial bone tunnels in the non-reattachment group were significantly reduced compared to those in the reattachment and PBS groups. Moreover, biomechanical testing showed that ultimate load-to-failure in the non-reattachment group tended to be larger than that in the reattachment group, though not statistically significant. The enhanced healing potential in the non-reattachment group was explained by the increase in intrinsic angiogenesis/osteogenesis. In the subacute phase, the ACL-derived cells with the non-reattached morphologic pattern showed greater and earlier tendon bone healing compared with the cells obtained from the reattached morphologic pattern.

Mechano Growth Factor Accelerates ACL Repair and Improves Cell Mobility of Mechanically Injured Human ACL Fibroblasts by Targeting Rac1-PAK1/2 and RhoA-ROCK1 Pathways

Exceeded mechanical stress leads to a sublethal injury to anterior cruciate ligament (ACL) fibroblasts, and it will hinder cell mobility and ACL regeneration, and even induce osteoarthritis. The mechano growth factor (MGF) could be responsible for mechanical stress and weakening its negative effects on cell physiological behaviors. In this study, effects of MGF on cell mobility and relevant molecules expression in injured ACL fibroblasts were detected. After an injurious mechanical stretch, the analysis carried out, at 0 and 24 h, respectively, showed that the cell area, roundness, migration, and adhesion of ACL fibroblasts were reduced. MGF (10, 100 ng/mL) treatment could improve cell area, roundness and promote cell migration and adhesion capacity compared with the injured group without MGF. Further study indicated that cell mobility-relevant molecules (PAK1/2, Cdc42, Rac1, RhoA, and ROCK1) expression in ACL fibroblasts was down-regulated at 0 or 24 h after injurious stretch (except Rac1 and RhoA at 0 h). Similarly, MGF improved cell mobility-relevant molecule expression, especially the ROCK1 expression level in ACL fibroblasts at 0 or 24 h after injurious stretch. Protein expression of ROCK1 in injured ACL fibroblasts was also reduced and could be recovered by MGF treatment. In a rabbit partial ACL transection (ACLT) model, ACL exhibited poor regenerative capacity in collagen and extracellular matrix (ECM) synthesis after partial ACLT for 2 or 4 weeks, and MGF remarkably accelerated ACL regeneration and restored its mechanical loading capacity after partial ACLT for four weeks. Our findings suggest that MGF weakens the effects of pathological stress on cell mobility of ACL fibroblasts and accelerates ACL repair, and might be applied as a future treatment approach to ACL rupture in the clinic.

Intraoperative pivot-shift accelerometry combined with anesthesia improves the measure of rotatory knee instability in anterior cruciate ligament injury

PurposeThe knee stiffness acquired following an Anterior Cruciate Ligament (ACL) injury might affect clinical knee tests, i.e., the pivot-shift maneuver. In contrast, the motor effects of spinal anesthesia could favor the identification of rotatory knee deficiencies prior to ACL reconstruction. Hence, we hypothesized that the intra-operative pivot-shift maneuver under spinal anesthesia generates more acceleration in the lateral tibial plateau of patients with an injured ACL than without.MethodsSeventy patients with unilateral and acute ACL rupture (62 men and 8 women, IKDC of 55.1 ± 13.8 pts) were assessed using the pivot-shift maneuver before and after receiving spinal anesthesia. A triaxial accelerometer was attached to the skin between Gerdys’ tubercle and the anterior tuberosity to measure the subluxation and reduction phases. Mixed ANOVA and multiple comparisons were performed considering the anesthesia and leg as factors (alpha = 5%).ResultsWe found a higher acceleration in the injured leg measured under anesthesia compared to without anesthesia (5.12 ± 1.56 m.s− 2 vs. 2.73 ± 1.19 m.s− 2, p < 0.001), and compared to the non-injured leg (5.12 ± 1.56 m.s− 2 vs. 3.45 ± 1.35 m.s− 2, p < 0.001). There was a presence of significant interaction between leg and anesthesia conditions (p < 0.001).ConclusionsThe pivot-shift maneuver performed under anesthesia identifies better rotatory instability than without anesthesia because testing the pivot-shift without anesthesia underestimates the rotatory subluxation of the knee by an increased knee stiffness. Thus, testing under anesthesia provides a unique opportunity to determine the rotational instability prior to ACL reconstruction.

State of the mineralized tissue comprising the femoral ACL enthesis in young women with an ACL failure.

Despite poor graft integration among some patients that undergo an anterior cruciate ligament (ACL) reconstruction, there has been little consideration of the bone quality into which the ACL femoral tunnel is drilled and the graft is placed. Bone mineral density of the knee decreases following ACL injury. However, trabecular and cortical architecture differences between injured and non-injured femoral ACL entheses have not been reported. We hypothesize that injured femoral ACL entheses will show significantly less cortical and trabecular mass compared with non-injured controls. Femoral ACL enthesis explants from 54 female patients (13-25 years) were collected during ACL reconstructive surgery. Control explants (n = 12) were collected from seven donors (18-36 years). Injured (I) femoral explants differed from those of non-injured (NI) controls with significantly less (p ≤ 0.001) cortical volumetric bone mineral density (vBMD) (NI: 736.1-867.6 mg/cm3 ; I: 451.2-891.9 mg/cm3 ), relative bone volume (BV/TV) (NI: 0.674-0.867; I: 0.401-0.792) and porosity (Ct.Po) (NI: 0.133-0.326; I: 0.209-0.600). Injured explants showed significantly less trabecular vBMD (p = 0.013) but not trabecular BV/TV (p = 0.314), thickness (p = 0.412), or separation (p = 0.828). We found significantly less cortical bone within injured femoral entheses compared to NI controls. Lower cortical and trabecular bone mass within patient femoral ACL entheses may help explain poor ACL graft osseointegration outcomes in the young and may be a contributor to the osteolytic phenomenon that often occurs within the graft tunnel following ACL reconstruction.

Using the Remnant Anterior Cruciate Ligament to Improve Knee Stability: Biomechanical Analysis Using a Cadaveric Model.

Background:Injured anterior cruciate ligament (ACL) tissue retains proprioceptive nerve fibers, vascularity, and biomechanical properties. For these reasons, remnant ACL tissue is often preserved during the treatment of ACL injuries.Purpose:To assess through a cadaveric model whether reorienting and retensioning the residual ACL via an osteotomy improves knee stability after partial ACL tear, with substantial remnant tissue and intact femoral and tibial attachments.Study Design:Controlled laboratory study.Methods:In 8 adult cadaveric knees, we measured anterior tibial translation and rotational laxity at 30° and 90° of flexion with the ACL in its native state and in 3 conditions: partial tear, retensioned, and ACL-deficient. The partial-tear state consisted of a sectioned anteromedial ACL bundle.Results:In the native state, the translation was 10 ± 2.7 mm (mean ± SD) at 30° of flexion and 8.4 ± 3.6 mm at 90° of flexion. Anterior translation of the knees in the partial-tear state (14 ± 2.7 mm at 30° and 12 ± 2.7 mm at 90°) was significantly greater than baseline (P < .001 for both). Translation in the ACL-retensioned state (9.2 ± 1.7 mm at 30° and 7.2 ± 2.1 mm at 90°) was significantly less than in the ACL-deficient state (P < .001 for both), and translation was not significantly different from that of the intact state. For ACL-deficient knees, translation (20 ± 4.3 mm at 30° and 16 ± 4.4 mm at 90°) was significantly greater than all other states (P < .001 for all). Although rotational testing demonstrated the least laxity at 30° and 90° of flexion in the retensioned and intact states and the most laxity in the ACL-deficient state, rotation was not significantly different among any of the experimental states.Conclusion:In a cadaveric model of an incomplete ACL tear, a reorienting and retensioning core osteotomy at the tibial insertion of the remnant ACL improved anteroposterior translation of the knee without compromising its rotational laxity.Clinical Relevance:The findings of this study support the concept of ACL tissue reorienting and retensioning in the treatment of ACL laxity as an area for future investigation.

Change in Collagen Fibril Diameter Distribution of Bovine Anterior Cruciate Ligament upon Injury Can Be Mimicked in a Nanostructured Scaffold

More than 200,000 people are suffering from Anterior Cruciate Ligament (ACL) related injuries each year in the US. There is an unmet clinical demand for improving biological attachment between grafts and the host tissue in addition to providing mechanical support. For biological graft integration, it is important to provide a physiologically feasible environment for the host cells to enable them to perform their duties. However, behavior of cells during ACL healing and the mechanism of ACL healing is not fully understood partly due to the absence of appropriate environment to test cell behavior both in vitro and in vivo. This study aims at (i) investigating the change in fibril diameter of bovine ACL tissue upon injury and (ii) fabricating nanofiber-based scaffolds to represent the morphology and structure of healthy and injured ACL tissues. We hypothesized that distribution and mean diameter of ACL fibrils will be altered upon injury. Findings revealed that the collagen fibril diameter distribution of bovine ACL changed from bimodal to unimodal upon injury with subsequent decrease in mean diameter. Polycaprolactone (PCL) scaffold fiber diameter distribution exhibited similar bimodal and unimodal distribution behavior to qualitatively represent the cases of healthy and injured ACL, respectively. The native ACL tissue demonstrated comparable modulus values only with the aligned bimodal PCL scaffolds. There was significant difference between mechanical properties of aligned bimodal and unaligned unimodal PCL scaffolds. We believe that the results obtained from measurements of diameter of collagen fibrils of native bovine ACL tissue can serve as a benchmark for scaffold design.