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Anterior cruciate ligament (ACL) is one of the most difficult tissues to heal once injured. Ligament regeneration and tendon-bone junction healing are two major goals of ACL reconstruction. This study aimed to investigate the synergistic therapeutic effects of Stromal cell-derived factor 1 (SDF-1)-releasing collagen-silk (CSF) scaffold combined with intra-articular injection of ligament-derived stem/progenitor cells (LSPCs) for ACL regeneration and the amelioration in the long-term complication of osteoarthritis (OA). The stem cell recruitment ability of CSF scaffold and the multipotency, particularly the tendon forming ability of LSPCs from rabbits were characterized in vitro, while the synergistic effect of the CSF scaffold and LSPCs for ACL regeneration and OA amelioration were investigated in vivo at 1, 3, and 6 months with a rabbit ACL reconstruction model. The CSF scaffold was used as a substitute for the ACL, and LSPCs were injected into the joint cavity after 7 days of the ACL reconstruction. CSF scaffold displayed a controlled release pattern for the encapsulated protein for up to 7 days with an increased stiffness in the mechanical property. LSPCs, which exhibited highly I Collagen and CXCR4 expression, were attracted by SDF-1 and successfully relocated into the CSF scaffold at 1 month in vivo. At 3 and 6 months post-treatment, the CSF scaffold combined with LSPCs (CSFL group) enhanced the regeneration of ACL tissue, and promoted bone tunnel healing. Furthermore, the OA progression was impeded efficiently. Our findings here provided a new strategy that using stem cell recruiting CSF scaffold with tissue-specific stem cells, could be a promising solution for ACL regeneration. Statement of Significance In this study, we developed a silk scaffold with increased stiffness and SDF-1 controlled release capacity for ligament repair. This advanced scaffold transplantation combined with intra-articular injection of LSPCs (which was isolated from rabbit ligament for the first time in this study) promoted the regeneration of both the tendinous and bone tunnel portion of ACL. This therapeutic strategy also ameliorated cartilage degeneration and reduced the severity of arthrofibrosis. Hence, combining LSPCs injection with SDF-1-releasing silk scaffold is demonstrated as a therapeutic strategy for ACL regeneration and OA treatment in the clinic. [ABSTRACT FROM AUTHOR]

Objective High-resolution peripheral quantitative computed tomography (HR-pQCT) is a novel imaging modality capable of visualizing bone microarchitecture in vivo at human peripheral sites such as the distal radius and distal tibia. This research has extended the technology to provide a non-invasive assessment of bone microarchitecture at the human knee by establishing new hardware, imaging protocols and data analysis. Design A custom leg holder was developed to stabilize a human knee centrally within a second generation HR-pQCT field of view. Five participants with anterior cruciate ligament reconstructions had their knee joint imaged in a continuous scan of 6 cm axially. The nominal isotropic voxel size was 60.7 μm. Bone mineral density and microarchitecture were assessed within the weight-bearing regions of medial and lateral compartments of the knee at three depths from the weight-bearing articular bone surface, including both the cortical and trabecular bone regions. Results Scan duration was approximately 18 min per knee and produced 5 GB of projection data and 10 GB of reconstructed image data (2304 × 2304 image matrix, 1008 slices). Motion during the scan was minimized by the leg holder and was similar in magnitude as a scan of the distal tibia. Bone mineral density and microarchitectural parameters were assessed for 16 volumes of interest in the tibiofemoral joint. Conclusions This is a new non-invasive in vivo assessment tool for bone microarchitecture in the human knee that provides an opportunity to gain insight into normal, injured and surgically reconstructed human knee bone architecture in cross-sectional or longitudinal studies. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament (ACL), a structure involved in providing knee stability, is an important restraint for anterior tibial translation and secondary restraint for internal tibial rotation. Injury to ACL, leading to its rupture can cause a lot of problems such as effect on knee stability, cartilage wear and other joint structures. Understanding the anatomy, physiology and the mechanical behavior is important as it helps in the understanding of its function and healing capacity after injury. This review takes a brief look at the anatomy, physiology and mechanical behavior of ACL. The causes of injury and healing process of ACL have also been discussed. This review gives an overview of the surgical treatment options for ACL rupture. These treatment options include methods that have been abandoned like primary repair, methods that are currently in use like the biological grafts and prosthetic grafts that are no longer being used (except LARS which is currently not used widely) due to the complications associated with them. Non-surgical, conservative treatment options for ACL have also been discussed. [ABSTRACT FROM AUTHOR]

Quadriceps strengthening exercises designed for the early phase of anterior cruciate ligament (ACL) rehabilitation should limit the anterior tibial translation developed by quadriceps contraction near full knee extension, in order to avoid excessive strain on the healing tissue. We hypothesize that knee-flexion exercises with simultaneous voluntary contraction of quadriceps (voluntary quadriceps cocontraction) can yield considerable levels of quadriceps activation while preventing the tibia from translating forward relative to the femur. Electromyographic activity in quadriceps and hamstring muscles was measured in 20 healthy males during isometric knee-flexion exercises executed near full knee extension with maximal voluntary effort of quadriceps cocontraction and external resistance ( R ) ranging from 0% to 60% of the 1-repetition maximum (1RM). Biomechanical modeling was applied to derive the shear (anterior/posterior) tibiofemoral force developed in each exercise condition. Isometric knee-flexion exercises with small external resistance ( R =10% 1RM) and maximal voluntary effort of quadriceps cocontraction yielded a net posterior (ACL-unloading) tibial pull ( P =0.005) and levels of activation of 32%, 50%, and 45% of maximum voluntary isometric contraction, for the rectus femoris, vastus medialis, and vastus lateralis, respectively. This exercise might potentially rank as one of the most appropriate quadriceps strengthening interventions in the early phase of ACL rehabilitation. [ABSTRACT FROM AUTHOR]

Introduction: Proprioceptive knee braces have been shown to improve knee mechanics, however much of the work to date has focused on tasks such as slow step down tasks rather than more dynamic sporting tasks.Objective: This study aimed to explore if such improvements in stability may be seen during faster sports specific tasks as well as slower tasks.Method: Twelve subjects performed a slow step down, single leg drop jump and pivot turn jump with and without a silicone web brace. 3D kinematics of the knee were collected using a ten camera Qualisys motion analysis system. Reflective markers were placed on the foot, shank, thigh and pelvis using the Calibrated Anatomical Systems Technique. A two way ANOVA with repeated measures was performed with post-hoc pairwise comparison to explore the differences between the two conditions and three tasks.Results: Significant differences were seen in the knee joint angles and angular velocities in the sagittal, coronal and transverse planes between the tasks. The brace showed a reduction in knee valgum and internal rotation across all tasks, with the most notable effect during the single leg drop jump and pivot turn jump. The transverse plane also showed a significant reduction in the external rotation knee angular velocity when wearing the brace.Discussion: The brace influenced the knee joint kinematics in coronal and transverse planes which confirms that such braces can have a significant effect on knee control during dynamic tasks. Further studies are required exploring the efficacy of proprioceptive braces in athletic patient cohort. [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) rupture is a common lesion. Current treatment emphasizes arthro-scopic ACL reconstruction via a graft, although this approach is associated with potential drawbacks. A new method of dynamic intraligamentary stabilization (DIS) was subjected to biomechanical analysis to determine whether it provides the necessary knee stability for optimal ACL healing. Methods: Six human knees from cadavers were harvested. The patellar tendon, joint capsule and all muscular attachments to the tibia and femur were removed, leaving the collateral and the cruciate ligaments intact. The knees were stabilized and the ACL kinematics analyzed. Anterior-posterior (AP) stability measurements evaluated the knees in the following conditions: (i) intact ACL, (ii) ACL rupture, (iii) ACL rupture with primary stabilization, (iv) primary stabilization after 50 motion cycles, (v) ACL rupture with DIS, and (vi) DIS after 50 motion cycles. Results: After primary suture stabilization, average AP laxity was 3.2 mm, which increased to an average of 11.26 mm after 50 movement cycles. With primary ACL stabilization using DIS, however, average laxity values were consistently lower than those of the intact ligament, increasing from an initial AP laxity of 3.00 mm to just 3.2 mm after 50 movement cycles. Conclusions: Dynamic intraligamentary stabilization established and maintained close contact between the two ends of the ruptured ACL, thus ensuring optimal conditions for potential healing after primary reconstruction. The present ex vivo findings show that the DIS technique is able to restore AP stability of the knee. [ABSTRACT FROM AUTHOR]

Aims: The purpose of this study was to determine the optimal clinical and cost-effective strategy for managing people following ACL rupture. Methods: A systematic review of the published (AMED, CINAHL, MEDLINE, EMBASE, PubMed, psycINFO and the Cochrane Library) and unpublished literature (OpenGrey, the WHO International Clinical Trials Registry Platform, Current Controlled Trials and the UK National Research Register Archive) was conducted on April 2013. All randomised and non-randomised controlled trials evaluating clinical or health economic outcomes of isolated ligament reconstruction versus non-surgical management following ACL rupture were included. Methodological quality was assessed using the PEDro appraisal tool. When appropriate, meta-analysis was conducted to pool data. Results: From a total of 943 citations, sixteen studies met the eligibility criteria. These included 1397 participants, 825 who received ACL reconstruction versus 592 who were managed non-surgically. The methodological quality of the literature was poor. The findings indicated that whilst reconstructed ACL offers significantly greater objective tibiofemoral stability (p b 0.001), there appears limited evidence to suggest a superiority between reconstruction versus non-surgical management in functional outcomes. There was a small difference between the management strategies in respect to the development of osteoarthritis during the initial 20 years following index management strategy (Odds Ratio 1.56; p = 0.05). Conclusions: The current literature is insufficient to base clinical decision-making with respect to treatment opinions for people following ACL rupture. Whilst based on a poor evidence, the current evidence would indicate that people following ACL rupture should receive non-operative interventions before surgical intervention is considered. [ABSTRACT FROM AUTHOR]

Background: Optimal therapy for anterior cruciate ligament (ACL) rupture in the paediatric population still provokes controversy. Although conservative and operative treatments are both applied, operative therapy is slightly favored. Among available surgical techniques are physeal-sparing reconstruction and transphyseal graft fixation. The aim of this study was to present our mid-term results after transphyseal ACL reconstruction. Methods: Fifteen young patients (mean age = 12.8 ± 2.6, range = 6.2-15.8 years, Tanner stage = 2-4) with open physis and traumatic anterior cruciate rupture who had undergone transphyseal ACL reconstruction with unilateral quadriceps tendon graft were prospectively analyzed. All children were submitted to radiological evaluation to determine the presence of clearly open growth plates in both the distal femur and proximal tibia. Postoperatively, all patients were treated according to a standardized rehabilitation protocol and evaluated by radiographic analysis and the Lysholm-Gillquist and IKDC 2000 scores. Their health-related quality of life was measured using the SF-12 PCS (physical component summary) and MCS (mental component summary) questionnaires. Results: Mean postoperative follow-up was 4.1 years. Mean Lysholm-Gillquist score was 94.0. Thirteen of the 15 knees were considered nearly normal on the IKDC 2000 score. The mean SF-12 questionnaire score was 54.0 ± 4.8 for SF-12 PCS and 59.1 ± 3.7 for SF-12MCS. No reruptures were observed. Radiological analysis detected one knee with valgus deformity. All patients had a normal gait pattern without restrictions. Conclusion: Transphyseal reconstruction of the anterior cruciate ligament shows satisfactory mid-term results in the immature patient. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The purpose of this investigation was to examine adolescent athletes' injury recovery and return-to-sport experiences. Given previous research highlighting competence, autonomy, and relatedness concerns among returning athletes (Podlog & Eklund, 2006), we sought to examine the extent to which basic psychological needs theory (BPNT: Ryan & Deci, 2007) could be used as framework for interpreting the research findings. Design: A qualitative design was employed in the present investigation. Method: Eleven Australian athletes (M age = 15.3) who had incurred a range of severe injuries (e.g., anterior cruciate ligament tears, shoulder dislocations) were interviewed on 2–3 occasions (n = 27 interviews) spanning an 11-month period. Results: Analysis of the data revealed the following four key themes: (a) injury stress, (b) coping strategies, (c) experiences with social support, and (d) recovery outcomes. Injury stress provides insights into a range of stressors and strain responses reported by the adolescents across the recovery phases, while the theme on coping highlights the specific strategies used to maintain motivation, reduce uncertainties associated with the injury experience, and to keep focused on future athletic attainment. The third theme, experiences with social support, considers the transactions the adolescents held with members of their social network throughout their recovery. The final theme, recovery outcomes, describes participant perceptions of a successful/unsuccessful recovery and stress-related growth. Conclusions: Results suggest that competence and relatedness issues highlighted in BPNT may be relevant in exploring adolescent athletes' injury experience. Somewhat less evidence for the autonomy dimension of BPNT was apparent in adolescent comments. [Copyright &y& Elsevier]

Background: There is no study comparing tibial tunnel widening after hamstring anterior cruciate ligament (ACL) reconstructions between RigidFix(r) and Bio-TransFix(r). Methods: Hamstring ACL reconstructions using RigidFix(r) in 56 patients and Bio-TransFix(r) in 41 with a minimum of 2 years postoperative evaluation were reviewed. Tibial fixation was performed using Intrafix in both groups. On the anterior-posterior (AP) and lateral radiographs, the diameter of the tibial tunnel was measured at proximal, middle, and distal positions. Postoperative laxity evaluations were performed using Lachman test, pivot-shift test, and instrumented laxity testing using the KT-1000 arthrometer. Results: On the AP and lateral radiographs, the average diameter of the tibial tunnel in the Bio-TransFix(r) group significantly increased after 6 months compared to the immediate postoperative measurement (p=0.002 and p=0.002, respectively). However, the average diameter of the tibial tunnel in the RigidFix(r) group did not increase after 6 months compared to the immediate postoperative measurement. Tunnel widening at 12months postoperatively in the Bio-TransFix(r) group was significantly more than that of the RigidFix(r) group on AP and lateral radiographs (p=0.012 and 0.016, respectively). Tunnelwidening at 24 months postoperatively showed a significant difference between the two groups (p=0.000 and 0.000, respectively). Fifteen patients (36.6%) in the Bio-TransFix(r) group and 15 patients (26.8%) in the RigidFix(r) group showed tunnel widening. There were no significant differences in results of the Lachman and pivot-shift tests, and mean KT-1000 measurement between the two groups. Conclusion: The Bio-TransFix(r) group showed progressive tibial tunnel widening after 6 months postoperatively but no clinical signs of instability. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

Abstract: Background: Anterior cruciate ligament rupture is the most common knee ligament injury sustained by active individuals, and the relative injury risk is sex-specific. Women not only demonstrate an increased risk for injury, but also a poorer response following ligament rupture. Perturbation training has shown positive results in healthy females, but gender-specific responses to training after injury have not been evaluated. The purpose of this investigation was to describe the effects of perturbation training on the gait characteristics of male and female non-copers. Methods: Biomechanical data were collected before and after training on 12 male and nine female non-copers using standard motion analysis techniques. Subjects walked at a consistent, self-selected speed over an embedded force plate. Data from both limbs were post-processed and analyzed using a mixed model analysis of variance and minimal clinically important differences to compare the limb behaviors of men and women. Findings: Prior to training, only women demonstrated significant hip joint excursion asymmetry (ES=1.03; P =0.009). Minimal clinically important difference values showed that the involved limb of the women had reduced hip and knee flexion angles and moments, truncated knee excursions, and increased hip excursions when compared to their own uninvolved limb and the limbs of the male non-copers. Following training, only knee extensor moment values exceeded the minimal clinically important differences in women. Interpretation: Female non-copers demonstrated unique movement strategies following injury and perturbation training. Women may be a meaningful subgroup of non-copers, and future investigations should consider the effects of gender in the outcomes of non-copers. [Copyright &y& Elsevier]

Abstract: Objective: The development of osteoarthritis following traumatic anterior cruciate ligament (ACL) injury is well established. However, few reliable indicators of early osteoarthritic changes have been established, which has limited the development of effective therapies. T 1ρ and T 2 mapping techniques have the ability to provide highly accurate and quantitative measurements of articular cartilage degeneration in vivo. Relating these cartilaginous changes to high-resolution bone-densitometric evaluations of the late-stage osteoarthritic bone is crucial in elucidating the mechanisms of development of traumatic osteoarthritis (OA) and potential therapies for early- or late-stage intervention. Methods: Twelve rabbits were monitored with in vivo magnetic resonance imaging (MRI) scans following ACL transection surgery with a contralateral leg sham operation. Six of the rabbits were treated with oral doxycycline for the duration of the experiment. At 12 weeks, the excised knees from three animals from each group (n=6 overall) were subjected to micro-computed tomography (CT) analysis. Results: Consistent with previous studies, initial elevations in T 1ρ and T 2 values in ACL-transected animals were observed with relative normalization towards values see in sham-operated legs over the 12-week study. This biphasic pattern could hold diagnostic potential to differentiate osteoarthritic cartilage by tracking the relative proportions of T 1ρ and T 2 values as they rise with inflammation then fall as collagen and proteoglycan loss leads to further dehydration. The addition of doxycycline resulted in inconclusive, yet potentially interesting, cartilaginous changes in several compartments of the rabbit legs. Micro-CT studies demonstrated decreased bone densitometrics in ACL-transected knees. Correlation studies suggest that the cartilaginous changes may be associated with some aspects of bony change and the development of OA. Conclusion: We conclude that there are definite relationships between cartilaginous changes as seen on MRI and late-stage microstructural bony changes after traumatic ACL injury in rabbits. In addition, doxycycline may show promise in mitigating early-stage cartilage damage that may serve to lessen late-stage osteoarthritic changes. This study demonstrates the ability to track OA progression and therapeutic efficacy with imaging modalities in vivo. [Copyright &y& Elsevier]

Objective Functional knee instability due to rupture of the anterior cruciate ligament (ACL), is difficult to measure in the clinic setting, thereby limiting the monitoring of deficiencies and the choice of treatments. This prospective and observational study aims to quantify the motor asymmetry associated with knee instability after ACL rupture, over ambulation tasks on forceplates. Material/patients and methods Five subjects with ACL rupture occurring in the 2 months before enrolment (ACL group, 5F, age 24 ± 3) and five healthy subjects (control group, CTL, age 24 ± 5) paired by age and sex, were evaluated barefoot using six forceplates in a movement analysis laboratory. All participants performed linear displacements at comfortable and fast walking speed as well as slow running (3 × 6 meters/task), angular displacements with lateral and medial rotations (3 trials/side/task), and bipodal (3 trials) and unipodal jumps (3 trials/side). Nine temporal and dynamic parameters were bilaterally measured: duration of stance (tstance), flight (tflight), reception (treception) and propulsion (tpropulsion), maximal ground reaction force in medial, lateral, anterior, posterior, and vertical directions (respectively, Fmed, Flat, Fant, Fpos, Fver), and root mean square of the vertical ground reaction force moment (Mz). For each parameter, we calculate the asymmetry index, defined as the difference between the dominant and the non-dominant legs in CTL and between the injured and non-injured legs in ACL divided by the dominant or non-injured side. Mann-Whitney tests were used to compare asymmetry between ACL and CTL (significance, P < 0.05). Results The asymmetry index was higher in ACL compared with CTL for tstance in fast walking speed ( P = 0.009), tflight in bilateral jump ( P = 0.07), Fver in comfortable walking speed ( P = 0.02) and in unipodal jump (p = 0.02) and Flat in angular displacement with lateral rotation ( P = 0.07). Others results were non-significant. Discussion/conclusion Functional ambulation tasks in the lab, including fast ambulation and jumps, using force plates, may provide objective quantification of temporal and dynamic asymmetry associated with ACL rupture. [ABSTRACT FROM AUTHOR]

Objective After anterior cruciate ligament (ACL) tear, the ACL reconstruction (ACLR) is the standard treatment to return to pivots/contacts sports. The goal of rehabilitation programs is to guide the functional recovery and the safe return to sport without additional knee injury or other injuries. Functional tests, like Hop tests and their side to-side difference index [limb symmetry index (LSI)], are commonly used following ACLR to help return to sport decision making. However, the most commonly used criterion to return to sport is the postoperative time: return to light activities (RtlA) at 3 or 4 month mark and return to sport with contacts and side-cuttings (RtS) between 6 and 9 month mark. The aim of this study was to analyse the functional recovery after ACLR using the standard hops LSI scores and compare these scores with usual timeline of RtlA and RtS. Patients and methods Thirty-one patients with ACLR (19 males) with a mean age of 23 ± 7 years. Functional recovery was evaluated during rehabilitation and return to sports phases (from 3 to 12 months postoperatively), with 2 straight one-legged Hop tests for distance (Single and Triple Hop tests). The LSI was calculated for each test. A non-linear regression was calculated to obtain predictive values of 3, 4, 6 and 9 months postoperatively. Results At 3 months, Hop tests LSI was nearly 80%, with great variability [interquartile range (IQR): 75%–95%]. At 4 months, Hop tests LSI was just under 85% but with important variability (IQR: 78%–94%). At 6 months, Hop tests LSI was about 90%, and over 90% at 9 months. From 6 postoperatively, the variability decreased (IQR: 94%–99%). Discussion/Conclusion Comparing our results with the usual timeline of RtlA, we can say that the timeline of 3 months postoperatively is a little too short to RtlA. At 4 months postoperatively, the functional recovery can allow a safely RtlA. At 6 months postoperatively, the LSI is greater than 90%, allowing RtS. Given the great variability between patients before 6 months postoperatively, this functional assessment could be used in association with clinical and isokinetic evaluations to individualize the decision to return to sport. [ABSTRACT FROM AUTHOR]

Objective Several ways exist to assess return to sport (RTS) after anterior cruciate ligament tear (ACLT): main sport or anterior level, pivoting contact sports or competition. Performing a relevant evaluation is difficult especially for moderate level patients. Our objective was to evaluate the reliability of these different outcomes after ACLT; then to assess the concordance between each other. Patients and methods Fifty-eight patients with moderate sport level were included (mean age 33.6 ± 12.4 years; 38 men vs. 20 women; 69% of operated, at 17.1 ± 5.3 months; Tegner before injury at 6.3 ± 1.9 vs. 4.9 ± 1.7 after RTS). Return to sport was declarative patients answering yes/no to main sport, previous level, pivoting contact sport, competition. A global level of RTS was measured as the variation of Tegner score and weekly hours of practice before/after ACLT (Tegner score × weekly hours of practice). Results Fifty-one percent of patients returned to main sport, 28% to anterior level (of whom 56% to anterior level of main sport), 31% to same global activity level, 19% to competition, 43% to pivoting contact sport. “Tegner.hour score” has decreased by 16.3 ± 33.6 after surgery. There was a strong discordance between declarative RTS and return to similar global activity level with Kappa coefficient respectively of 0.19, 0.17, 0.05 and 0.29 for main sport, previous level, pivoting contact sport, competition. Discussion/Conclusion We confirmed low RTS rates with a clear discordance between different outcomes of RTS. Considering the global activity volume calculated with Tegner score (Tegner.hour) is an interesting alternative scale to evaluate RTS for moderate sport level patients. [ABSTRACT FROM AUTHOR]