Biomechanics of the anterior cruciate ligament: Physiology, rupture and reconstruction techniques

Lower limbs kinematic analysis during a jump landing task in soccer players with unilateral anterior cruciate ligament reconstruction

BACKGROUND

Fatigue leads to an acute decline in muscle strength, altered patterns of lower extremity muscle activation, changes in hip and knee kinematics. In terms of the effects of fatigue on knee joint kinematics during plyometric training, there is still a lack of knowledge regarding kinematic differences between athletes who passed the ACL reconstructions rehabilitation period and healthy athletes. Therefore, this study aimed to compare lower limb joint kinematic parameters between reconstructed cruciate ligament and healthy control soccer players during jump landing in a fatigued setting.

METHODS

Lower limb kinematic parameters were recorded in 20 professional soccer players (age, 24.95 ± 2.92 years; body mass, 77.20 ± 12.88 kg; height, 1.77 ± 3.19 m) during jump landing task before and after the fatigue protocol. The control group consisted of healthy subjects and the experimental group consisted of subjects with ACL reconstruction by thigh transplantation. Kinematic data was recorded with 4 cameras to measure lower limb angles at first foot contact and maximum range of motion.

RESULTS

The results showed that before fatigue, there was only a significant difference between the two groups in the maximum range of motion of the non-involved hip joint (P = 0.022) and angle of the involved hip at first contact (P = 0.049). In other data on joint range of motion or initial contact angle, no significant difference was observed between the two groups (P > 0.05). After fatigue protocol, there was a significant difference in initial foot contact in non-involved (P = 0.030), and involved (P = 0.020) hip joint angles between the two groups. However, no significant difference in initial contact angle or range of motion of other joints was observed between the groups.

CONCLUSIONS

This study shows that plyometric fatigue does not contribute to numerous changes in contact angles and range of motion in lower extremity joints in healthy soccer players and those with a history of cruciate ligament repairs.

DOES CRUCIATE LIGAMENT SUBSTITUTION AND IMPLANT ASYMMETRY MAKE A DIFFERENCE FOR TOTAL KNEE ARTHROPLASTY KINEMATICS? A MULTI-IMPLANT EVALUATION

BACKGROUND

The non-implanted knee differs in comparison to total knee arthroplasty (TKA) designs, with regard to asymmetry and functionality of the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). While surgeons may choose to implant either posterior stabilized (PS) or bi-cruciate stabilized (BCS) TKAs, substituting for one or both cruciate ligaments, the effects of symmetry versus asymmetry in substituting TKA designs have not been widely analyzed to determine possible benefits. Therefore, the objective of this research study was to determine if either TKA asymmetry and/or anterior ligament stabilization can lead to more normal-like kinematics and clinical benefit for patients.

METHODS

In vivo, femoro-tibial kinematics for 64 subjects were evaluated in this retrospective study. Overall, ten subjects had a normal, non-implanted knee, 20 had a BCS TKA, and 34 had one of two different PS TKAs. All three TKAs had varying degrees of symmetry incorporated into the design, and all were implanted by the same surgeon and were analyzed using fluoroscopy during a deep knee bend.

RESULTS

At full extension, the BCS TKA subjects demonstrated a statistically more anterior position of both condyles compared to both PS TKAs. The BCS TKA subjects also experienced more posterior femoral rollback and axial rotation in early flexion and from full extension to maximum knee flexion. Additionally, the TKAs in this study having asymmetry experienced greater amounts of posterior femoral rollback and weight-bearing knee flexion.

CONCLUSION

The results from this study indicated that in early flexion, the anterior cam/post mechanism does pull the femoral component more anterior, and all TKAs experienced posterior femoral rollback when the posterior cam engaged the post. The asymmetric designs also achieved greater rollback and axial rotation compared to the symmetric designs.

Anterior Cruciate Ligament Reconstruction in Young Athletes: A Comprehensive Review of Lateral Extra-Articular Tenodesis and Anterolateral Ligament Reconstruction Techniques

Anterior cruciate ligament (ACL) injuries are prevalent among young athletes and pose significant challenges due to their impact on immediate and long-term knee function. Traditional ACL reconstruction techniques, while effective, may not always meet the unique needs of this population, particularly given their high physical demands and the risk of future complications. This review evaluates two advanced surgical techniques - lateral extra-articular tenodesis (LEAT) and anterolateral ligament (ALL) reconstruction - as potential enhancements to conventional ACL reconstruction. LEAT involves augmenting knee stability by addressing lateral compartment issues, while ALL reconstruction focuses on reconstructing the ALL to improve overall knee function. The review compares these techniques regarding surgical procedures, clinical outcomes, biomechanical effectiveness, and complications. LEAT and ALL reconstruction are examined for their impact on recovery, return-to-sport rates, and long-term knee health, highlighting their advantages and limitations. Findings suggest that both techniques offer promising benefits, with the potential for improved outcomes compared to traditional methods. However, the effectiveness of each technique can vary based on individual factors and the specific demands of different sports. Further research is needed to fully understand the long-term implications and refine these approaches. This review aims to guide clinical decision-making and optimize treatment strategies for young athletes with ACL injuries, enhancing their prospects for a successful return to athletic activity.

Understanding the Structure-Function Relationship through 3D Imaging and Biomechanical Analysis: A Novel Methodological Approach Applied to Anterior Cruciate Ligaments

Understanding the microstructure of fibrous tissues, like ligaments, is crucial due to their nonlinear stress-strain behavior from unique fiber arrangements. This study introduces a new method to analyze the relationship between the microstructure and function of anterior cruciate ligaments (ACL). We tested the procedure on two ACL samples, one from a healthy individual and one from an osteoarthritis patient, using a custom tensioning device within a micro-CT scanner. The samples were stretched and scanned at various strain levels (namely 0%, 1%, 2%, 3%, 4%, 6%, 8%) to observe the effects of mechanical stress on the microstructure. The micro-CT images were processed to identify and map fibers, assessing their orientations and volume fractions. A probabilistic mathematical model was then proposed to relate the geometric and structural characteristics of the ACL to its mechanical properties, considering fiber orientation and thickness. Our feasibility test indicated differences in mechanical behavior, fiber orientation, and volume distribution between ligaments of different origins. These indicative results align with existing literature, validating the proposed methodology. However, further research is needed to confirm these preliminary observations. Overall, our comprehensive methodology shows promise for improving ACL diagnosis and treatment and for guiding the creation of tissue-engineered grafts that mimic the natural properties and microstructure of healthy tissue, thereby enhancing integration and performance in biomedical applications.

Management of Meniscus Pathology with Concomitant Anterior Cruciate Ligament Injury

PURPOSE OF REVIEW

The purpose of this review is to summarize current clinical knowledge on the prevalence and types of meniscus pathology seen with concomitant anterior cruciate ligament (ACL) injury, as well as surgical techniques, clinical outcomes, and rehabilitation following operative management of these pathologies.

RECENT FINDINGS

Meniscus pathology with concomitant ACL injury is relatively common, with reports of meniscus pathology identified in 21-64% of operative ACL injuries. These concomitant injuries have been associated with increased age and body mass index. Lateral meniscus pathology is more common in acute ACL injury, while medial meniscus pathology is more typical in chronic ACL deficiency. Meniscus tear patterns associated with concomitant ACL injury include meniscus root tears, lateral meniscus oblique radial tears of the posterior horn (14%), and ramp lesions of the medial meniscus (8-24%). These meniscal pathologies with concomitant ACL injury are associated with increased rotational laxity and meniscal extrusion. There is a paucity of comparative studies to determine the optimal meniscus repair technique, as well as rehabilitation protocol, depending on specific tear pattern, location, and ACL reconstruction technique. There has been a substantial increase in recent publications demonstrating the importance of meniscus repair at the time of ACL repair or reconstruction to restore knee biomechanics and reduce the risk of progressive osteoarthritic degeneration. Through these studies, there has been a growing understanding of the meniscus tear patterns commonly identified or nearly missed during ACL reconstruction. Surgical management of meniscal pathology with concomitant ACL injury implements the same principles as utilized in the setting of isolated meniscus repair alone: anatomic reduction, biologic preparation and augmentation, and circumferential compression. Advances in repair techniques have demonstrated promising clinical outcomes, and the ability to restore and preserve the meniscus in pathologies previously deemed irreparable. Further research to determine the optimal surgical technique for specific tear patterns, as well as rehabilitation protocols for meniscus pathology with concomitant ACL injury, is warranted.

Precise and efficient measurement of tibial slope on magnetic resonance imaging (MRI): two novel autonomous pipelines by traditional and deep learning algorithms

Background

The measurement of posterior tibial slopes (PTS) can aid in the screening and prevention of anterior cruciate ligament (ACL) injuries and improve the success rate of some other knee surgeries. However, the circle method for measuring PTS on magnetic resonance imaging (MRI) scans is challenging and time-consuming for most clinicians to implement in practice, despite being highly repeatable. Currently, there is no automated measurement scheme based on this method. To enhance measurement efficiency, consistency, and reduce errors resulting from manual measurements by physicians, this study proposes two novel, precise, and computationally efficient pipelines for autonomous measurement of PTS.

Methods

The first pipeline employs traditional algorithms with experimental parameters to extract the tibial contour, detect adhesions, and then remove these adhesions from the extracted contour. A cyclic process is employed to adjust the parameters adaptively and generate a better binary image for the following tibial contour extraction step. The second pipeline utilizes deep learning models for classifying MRI slice images and segmenting tibial contours. The incorporation of deep learning models greatly simplifies the corresponding steps in pipeline 1.

Results

To evaluate the practical performance of the proposed pipelines, doctors utilized MRI images from 20 patients. The success rates of pipeline 1 for central, medial, and lateral slices were 85%, 100%, and 90%, respectively, while pipeline 2 achieved success rates of 100%, 100%, and 95%. Compared to the 10 minutes required for manual measurement, our automated methods enable doctors to measure PTS within 10 seconds.

Conclusions

These evaluation results validate that the proposed pipelines are highly reliable and effective. Employing these tools can effectively prevent medical practitioners from being burdened by monotonous and repetitive manual measurement procedures, thereby enhancing both the precision and efficiency. Additionally, this tool holds the potential to contribute to the researches regarding the significance of PTS, particularly those demanding extensive and precise PTS measurement outcomes.

Peroneus Longus Tendon Autografts have Better Graft Diameter, Less Morbidity, and Enhanced Muscle Recuperation than Hamstring Tendon in ACL Reconstruction

Background

Recently the peroneus longus tendon (PLT) gained popularity in anterior cruciate ligament (ACL) reconstruction and has been utilized with satisfactory outcomes. However, there are concerns regarding donor site morbidity. This study aims to compare the functional outcome of ACL reconstruction using hamstring (HT) and PLT autografts and evaluate the donor site morbidity.

Methods

Patients who underwent ACL reconstruction were allocated to two groups (HT and PLT). Graft diameter was measured intraoperatively. Knee functional outcome was evaluated with IKDC and Tegner-Lysholm scores preoperatively, and postoperatively after 3 months, 6 months, and 1 year. Donor site morbidities were assessed with thigh circumference measurements, subjective evaluation of sensory disturbances, and ankle scoring with AOFAS and FADI scores.

Results

At 1-year follow-up, the PLT group showed comparable IKDC (p = 0.925) and Tegner-Lysholm (p = 0.600) scores with those of the HT group. The mean graft diameter in the PLT group (7.93 ± 0.52 mm) was larger compared with the HT group (7.43 ± 0.50 mm) (p < 0.001). The incidence of thigh atrophy (HT-16.7%, PLT-10%) and sensory disturbances (HT-73.3%, PLT-10%) was greater in the HT group. There was no significant ankle donor site morbidity in the PLT group (AOFAS-98.67 ± 3.45, FADI-99.23 ± 1.69).

Conclusion

ACL reconstruction with PLT had comparable functional outcome with that of HT at 1 year. However, PLT demonstrated larger graft diameter, less donor site morbidity, and enhanced muscle recovery without significantly affecting the ankle function. PLT can be safely used as an acceptable alternative graft choice harvested from outside the knee for ACL reconstruction.

Examining the Prevalence of Anterior Cruciate Ligament Injuries on Artificial Turf Surfaces Compared to Natural Grass Surfaces in Athletes: A Scoping Review

The anterior cruciate ligament (ACL) is commonly injured in sports such as American football and soccer. It is currently unknown if ACL injuries are more prevalent on natural grass or artificial turf fields. The purpose of this scoping review is to analyze research studies evaluating the effect of the playing surface on the prevalence of ACL injuries. We hypothesize that athletes face a greater risk of suffering ACL injuries while playing on artificial turf compared to natural grass. Our team conducted a comprehensive literature review by screening three databases (PubMed, Embase, and Cochrane) that comprised a wide range of peer-reviewed articles on ACL injuries suffered on natural grass and artificial turf surfaces. Inclusion criteria consisted of epidemiological and cohort studies published after 1990 that were written in English and focused on athletes ranging in skill level from youth to professional. Exclusion criteria consisted of biomechanical studies, review articles, and papers that focused on injuries of structures other than the ACL. Bias was assessed with the MINORS criteria. Results were presented by injury rates, calculated ratios, and confidence intervals. The final analysis included nine papers published in peer-reviewed journals. Three of nine papers found that ACL injuries are more likely to occur on artificial turf than on natural grass. Three papers found that there is no difference in the prevalence of ACL injuries between surfaces and one paper stated that ACL injuries are more likely on natural grass than artificial turf. Two papers did not report confidence intervals for ratios comparing injury rates between playing surfaces. There is no consensus in the current literature regarding the prevalence of ACL injuries on artificial turf versus natural grass surfaces. The primary limitation of this study was that the papers used a variety of methods to compare rates of ACL injuries on artificial and natural surfaces, making comparisons between the nine papers difficult.

Diagnostic Accuracy of Non-invasive Tests Versus Arthroscopy in Anterior Cruciate Ligament (ACL) Injuries

BACKGROUND

The knee joint assessment to detect anterior cruciate ligament (ACL) injury after trauma involves clinical examination and radiography. The gold standard method is doing arthroscopy. We did this study seeking to evaluate the effectiveness of other non-invasive diagnostic methods, including the Anterior Drawer test, Lachman test and magnetic resonance imaging (MRI) in detecting ACL tears after trauma, compared to the reference standard method (the arthroscopy).

METHODOLOGY

This descriptive cross-sectional study was conducted in the Orthopaedic Department of the Khyber Teaching Hospital, Peshawar, for six months. A total of 86 participants with knee injuries fulfilling the inclusion criteria were recruited for the study. Mechanism of injury, side of injury and body weight were recorded. The Anterior Drawer test and Lachman test for ACL injury were performed by orthopaedic surgeons with at least five years of post-fellowship experience in orthopaedic surgery. Sensitivities, specificities and accuracy of the clinical tests and MRI were calculated.

RESULTS

The statistical analysis revealed that the mean age of participants was 35.73 (SD 12.7) years, with a range from 18 to 55 years. Among the participants, 67 (77.91%) were male and 19 (22.09%) were female. The side of injury was predominantly right in 50 (58.14%) and left in 36 (41.86%) participants. Road traffic accidents (RTAs) were the leading cause of knee injury, accounting for 63.95% (55) of cases, followed by sports injuries at 23.26% (20). Regarding diagnostic accuracy, MRI showed a sensitivity of 98.57%, specificity of 87.50% and diagnostic accuracy of 96.51% in detecting ACL tears. The Lachman test demonstrated a sensitivity of 90%, specificity of 87.5% and diagnostic accuracy of 89.53% compared to arthroscopy. Similarly, the anterior Drawer test exhibited a sensitivity of 88.57%, specificity of 87.50% and diagnostic accuracy of 88.37% against the gold standard of arthroscopy. These findings underscore the effectiveness of these diagnostic modalities in identifying ACL injuries.

CONCLUSIONS

All three tests (MRI, Lachman test and anterior Drawer test) can be used for the diagnosis of anterior cruciate ligament injury with optimal results.

Functional Outcome of Single-Bundle Arthroscopic Anterior Cruciate Ligament Reconstruction using Peroneus Longus Graft and Hamstring Graft: An Open-Label, Randomized, Comparative Study

Background This study investigates the functional outcomes of single-bundle arthroscopic anterior cruciate ligament (ACL) reconstruction, comparing the use of two distinct graft sources: peroneus longus (PL) graft and hamstring graft. The choice of graft material in ACL reconstruction is crucial for optimal postoperative results, and this study aims to contribute valuable insights into the comparative efficacy of these two graft types. Method This open-label randomized comparative study involved a carefully selected cohort of patients undergoing single-bundle arthroscopic ACL reconstruction. Participants were randomly assigned to either the PL graft group or the hamstring graft group. Surgical procedures were conducted using standardized techniques, and postoperative rehabilitation protocols were closely monitored. Functional outcomes, including range of motion, stability, and patient-reported measures, were assessed at predefined intervals to ensure comprehensive data collection. Results The study underscores significant demographic and clinical factors in ACL reconstruction outcomes. Participants were predominantly aged 17-30 years (58.33%) with a mean age of 29.27 years and exhibited a male predominance (80.56%). Common complaints included knee pain and instability, primarily due to falls from bikes (55.56%) or sports-related trauma (44.44%). Notably, PL grafts demonstrated advantages over hamstring grafts, with longer mean length (10.11 mm vs. 8.77 mm, p=0.0001) and shorter operation times. Visual analog scale (VAS), International Knee Documentation Committee (IKDC), and Tegner Lysholm scores show no significant differences between grafts over the period of time. There is no notable foot eversion weakness or significant donor site morbidity after the PL graft harvest. Hamstring graft cases exhibit a higher incidence of altered sensation and muscle atrophy, suggesting the potential benefits of PL grafts for improved surgical outcomes. Conclusions Graft comparisons favored PL grafts due to longer length, and functional outcome assessments between the two graft types. However, foot and ankle strength assessments revealed fluctuations in strength recovery with PL grafts, highlighting the need for tailored rehabilitation. Thigh circumference variations suggested potential muscle atrophy in the hamstring graft group, along with reported paresthesia in the ipsilateral proximal leg. In conclusion, PL grafts offer potential advantages for ACL surgery, but ongoing monitoring and specialized rehabilitation are crucial.

The Integral Role of Physiotherapy in Combined Complete Anterior Cruciate Ligament and Posterior Cruciate Ligament Arthroscopic Reconstruction: A Case Report

Combined anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injuries are infrequent in clinical practice, often leading to severe knee instability and functional limitations. A 30-year-old male presented with right knee pain and swelling following a two-wheeler accident. Diagnostic investigations confirmed complete ACL and PCL tears. The surgical intervention comprised arthroscopic-assisted ACL reconstruction using semitendinosus and gracilis tendons, accompanied by arthroscopic PCL reconstruction. Postoperatively, structured physiotherapy rehabilitation was initiated. After 12 weeks of rehabilitation, significant improvements in range of motion and muscular strength were observed. Tailored physiotherapy facilitated prompt recovery, enhancing functional mobility and independent ambulation. This case highlights the efficacy of comprehensive surgical intervention followed by structured rehabilitation in achieving favorable outcomes in patients with combined ACL and PCL injuries. Tailored physiotherapy plays a crucial role in optimizing functional recovery and facilitates the enhancement of the patient's functional mobility and independent ambulation.

Epidemiology and distribution of cruciate ligament injuries in children and adolescents, with an analysis of risk factors for concomitant meniscal tear

Introduction

To investigate the epidemiological features and prevalence of cruciate ligament injuries (CLI) in children and adolescents, and to examine the potential risk factors associated with concomitant meniscal tear (MT) among this population.

Methods

The demographic data and injury details of children and adolescents with CLI from Southeast China were analyzed to describe their distribution characteristics, alongside an analysis of the prevalence of MTs, the most frequent complication. In addition, binary logistic analysis was employed to ascertain the risk factors linked to MT in individuals suffering from CLI.

Results

A total of 203 patients with CLI (n = 206) met the inclusion criteria, with a male-to-female ratio of 2.3:1. Notably, a higher proportion of females were aged ≤16 years old compared to males, who predominated in patients aged >16 years (P = 0.001). Among children and adolescents, anterior cruciate ligament (ACL) injuries were the primary type of CLI, accounting for 88.18% (179/203) of all cases. The majority of cases (132/203, 65.02%) were sustained during sports activities, and sprains were the predominant mechanism of injury (176/203, 86.7%). Additionally, the most common associated injury was an MT (157/203, 77.34%). The posterior horn is the most frequently affected site for both medial MT (62.93% out of 73 cases) and lateral MT (70.19% out of 73 cases). Moreover, vertical tears constituted the majority of medial MTs (59.48% out of 116 cases). Furthermore, patients with a higher BMI faced an increased risk of associated MT in comparison to non-overweight patients (88% vs. 73.86%; P = 0.038). Each increase in BMI unit was linked with a 14% higher probability of associated MT occurrence in children and adolescents with CLI (OR = 1.140; P = 0.036).

Discussion

ACL injuries are a common form of knee ligament injury among children and adolescents, especially those over the age of 16, and are often the result of a sprain. Meniscal posterior horn injury is the most commonly associated injury of youth with CLI. Additionally, overweight or obese people with CLI are at a greater risk of developing MT.

Changes in passive hamstring stiffness after primary anterior cruciate ligament reconstruction: A prospective study with comparison of healthy controls

BACKGROUND

The mechanical properties of knee flexors muscles contribute to reducing anterior cruciate ligament loading. This case-control study evaluated the passive knee flexors stiffness after primary anterior cruciate ligament reconstruction with comparison of healthy controls.

METHODS

After anterior cruciate ligament reconstruction, 88 participants (24.5 [8.6] years, 56,8% males) had two isokinetic tests at 4 and 8 postoperative months with measurement of the passive resistive torque of knee flexors and extensors/flexors strength. In the control group, 44 participants (24.5 [4.3] years, 56,8% males) had one visit with the same procedures. Passive knee flexors stiffness was calculated as the slope of the passive torque-angle curve on the last 10° of knee extension (Nm/°). We investigated the impact of timing and type of surgery (autograft and combined meniscus repair) and persistent knee extension deficits on knee flexors stiffness.

FINDINGS

At 4 and 8 postoperative months, passive knee flexors stiffness was lower on the operated limb than on the non-operated limb (P < 0.001) but both limbs had significant lower values than controls (P < 0.001). Stiffness was positively correlated with knee flexors strength (P < 0.010), and knee flexors stiffness at 4 months was lower in individuals who underwent surgery <6 months from injury (P = 0.040). Knee extension deficit or the type of surgery did not have a significant influence on knee flexors stiffness.

INTERPRETATION

Similarly to neuromuscular factors that are traditionally altered after anterior cruciate ligament reconstruction, evaluating passive knee flexors stiffness changes over time could provide supplementary insights into postoperative muscle recovery.

Examining Postoperative Posterior Cruciate Ligament Index: A Structural Paradigm in Anterior Cruciate Ligament (ACL) Reconstructions With Hamstring Tendon Autograft

BACKGROUND

The current study aimed to compare the posterior cruciate ligament (PCL) index values of patients who underwent hamstring tendon (HT) autograft reconstruction due to an anterior cruciate ligament (ACL) tear. The comparison involved assessing these values in a similar cohort and evaluating the association between the alteration in the PCL index and functional results.

METHODS

Patients who were clinically diagnosed with a complete, unilateral ACL tear and underwent ACL reconstruction (ACLR) using HT autograft between January 2018 and January 2021 constituted the operated group (Group 1) of the study. The control group (Group 2) consisted of patients selected from a convenience sample without ACL rupture, meniscal lesion, or cartilage damage who underwent an MRI during an outpatient orthopaedic consultation for knee pain. The operated group was submitted for an MRI of the knee one year after the operation for any reason such as pain, graft healing, the presence of tunnel widening, or suspicion of re-rupture. The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form and the Lysholm Scoring System were applied to the patients in the operated group in the preoperative and postoperative periods to evaluate their complaints, function, and participation in sports and to assess functional ability and functional capacity. A radiologist with five years of experience measured the PCL index in the sagittal section of an MRI. In the operated group, changes in PCL index, IKDC, and Lysholm values during the postoperative period were assessed, along with their correlation. Additionally, a comparison was made between the values of the operated group and the non-operated group.

RESULTS

No statistically significant correlation was found between the PCL index alteration and the functional score alteration (IKDC and Lysholm) in the operated group (p>0.05). In comparison to the non-operated group, the preoperative PCL index measures of the operated group were significantly lower (p: 0.000; p<0.05). The increase in the postoperative PCL index measurements of the operated group was similarly statistically significant (p: 0.000; p<0.05).

CONCLUSION

Although the PCL index appears to be a strong anatomical structural parameter in ACLR patients performing HT autograft in the postoperative period, its correlation with functional results is weak.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure

PURPOSE

To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts.

METHODS

In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities.

RESULTS

Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012).

CONCLUSIONS

This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health.

LEVEL OF EVIDENCE

Level III, retrospective database study.

Do Differences Exist in Impact Test Domains between Youth Athletes with and without an Anterior Cruciate Ligament Injury?

Poor baseline reaction time, as measured via the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), has been associated with anterior cruciate ligament (ACL) injury risk in adult athletes. Our study sought to determine whether the reaction time and impulse control ImPACT test domains differed between ACL injured and uninjured pediatric athletes. A total of 140 high-school aged athletes comprising 70 athletes who went on to sustain an ACL injury between 2012 and 2018 and 70 age- and sex-matched uninjured controls were included in the study. Mean reaction times were similar for the injured (0.67 s) and uninjured (0.66 s) athletes (p = 0.432), and the impulse control scores were also similar for those with (5.67) and without (6.07) an ACL injury (p = 0.611). Therefore, neurocognitive risk factors for sustaining an ACL injury in adults cannot necessarily be extrapolated to adolescent athletes. Further research is needed to understand why differences exist between injury risk in youth and adult athletes.

Epidemiology of Injuries in Professional and Amateur Football Men (Part II)

Background (1): Men's football is a physically demanding contact sport that involves intermittent bouts of sprinting, jogging, walking, jumping and changes of direction. The physical demands of the game vary by level of play (amateur club, sub-elite and open club or international), but injury rates at all levels of the men's football game remain the highest of all sports. Objective: The aim of this study is to conduct a systematic review of data from the epidemiological literature regarding the profile, severity and mechanisms of injuries and the frequency of recurrent injuries in professional and amateur football players. Methods (2): A systematic review, according to PRISMA guidelines, was performed up to June 2023 in the databases of PubMed, Web of Science, Google academic, Google scholar and the Diva portal. Twenty-seven studies that reported data on the type, severity, recurrence and mechanisms of injury in professional and amateur men's football were selected and analyzed. Two reviewers independently audited data and assessed the study quality using the additional and adapted version of the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement and the Newcastle Ottawa Scale (NOS) to assess risk of bias for the quality of external validity. Results (3): In professional male football players, the mean prevalence of muscle/tendon injuries was 39.78%, followed by joint and ligament injuries-21.13%, contusions-17.86%, and fractures-3.27%, and for amateur football players, the prevalence's were 44.56% (muscle/tendon injuries), 27.62% (joint and ligament injuries), 15.0% (contusions) and 3.05% (fracture), respectively. The frequency of traumatic injuries was higher in amateur football players (76.88%) compared to professional football players (64.16%), the situation being reversed in the case of overuse injuries: 27.62% in professional football players and 21.13% in amateur football players. Most contact injuries were found in professional footballers (50.70%), with non-contact injuries predominating in amateur footballers (54.04%). The analysis of the severity of injuries showed that moderate injuries dominated in the two categories of footballers; the severe injuries in amateur footballers exceeded the severe injuries recorded in professional footballers by 9.60%. Recurrence proportions showed an inverse relationship with the level of play, being higher in amateur footballers (16.66%) compared to professional footballers (15.25%). Conclusions (4): Football-related injuries have a significant impact on professional and amateur football players and their short- and long-term health status. Knowing the frequency of severe diagnoses, such as strains, tears and cramps of the thigh muscles, ankle ligament sprains and hip/groin muscle strain requires the establishment of adequate programs to prevent them, especially in amateur football players, who are more prone to serious injuries.

Knee lesions with anterior cruciate ligament (ACL) tear in Iraqi adult males: arthroscopic findings

This cross-sectional study aimed at exploring the frequency and extent of knee joint lesions associated with delayed treatment of anterior cruciate ligament (ACL) injury. It enrolled 300 patients from 2020 to 2022 who were subjected to arthroscopy for anterior cruciate ligament reconstruction. The sample was comprised of Iraqi adult male patients from different regions of Iraq, and the surgical procedure was carried out in Al-Diwaniyah Teaching Hospital. The findings were recorded by Karl Storz's camera system. Dissection and arthroscopy were done under general anesthesia using an anterolateral portal technique. The study employed a visualization of the anterior cruciate ligament probing the meniscus and reaching the posteromedial space for the ramp lesion. The mean age of patients was 28.05±6.92 years, ranging from 19 to 35 years and the mean duration from onset of injury to the time of operation was 3.69±1.07 years, ranging from 6 months to 10 years. The arthroscopic examination revealed medial meniscus tear in 80% of the cases, lateral meniscus tear in 40% of the cases, cartilage lesion in 40% of the cases, and meniscus ramp lesions in 10% of the cases. Most cases of ACL tear are associated with a meniscus injury, cartilage defect, and collateral ligament tear. These serious lesions, such as complex meniscus tears or full articular cartilage defects, are a direct consequence of delayed treatment. Consequently, it is crucial to inform the patients about the significant issues that can arise due to treatment delays.

Improved Cartilage Protection with Low Molecular Weight Hyaluronic Acid Hydrogel

Traumatic joint injuries are common, leading to progressive tissue degeneration and the development of osteoarthritis. The post-traumatic joint experiences a pro-inflammatory milieu, initiating a subtle but deteriorative process in cartilage tissue. To prevent or even reverse this process, our group previously developed a tissue-penetrating methacrylated hyaluronic acid (MeHA) hydrogel system, crosslinked within cartilage to restore and/or protect the tissue. In the current study, we further optimized this approach by investigating the impact of biomaterial molecular weight (MW; 20, 75, 100 kDa) on its integration within and reinforcement of cartilage, as well as its ability to protect tissue degradation in a catabolic state. Indeed, the low MW MeHA integrated and reinforced cartilage tissue better than the high MW counterparts. Furthermore, in a 2 week IL-1β explant culture model, the 20 kDa MeHA demonstrated the most protection from biphasic mechanical loss, best retention of proteoglycans (Safranin O staining), and least aggrecan breakdown (NITEGE). Thus, the lower MW MeHA gels integrated better into the tissue and provided the greatest protection of the cartilage matrix. Future work will test this formulation in a preclinical model, with the goal of translating this therapeutic approach for cartilage preservation.

Smaller diameter femoral tunnel biocomposite interference screws provide adequate fixation strength in anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to evaluate the effect of bioabsorbable interference screw diameter on the pullout strength and failure mode for femoral tunnel fixation in primary anterior cruciate ligament reconstruction (ACLR) at time zero fixation using bone-patellar tendon-bone (BTB) autograft in a cadaveric model.

METHODS

Twenty-four fresh-frozen cadaveric knees were obtained from 17 different donors. Specimens were allocated to three different treatment groups (n = 8 per group) based on interference screw diameter: 6 mm, 7 mm, or 8 mm biocomposite interference screw. All specimens underwent dual energy X-ray absorptiometry (DEXA) scanning prior to allocation to ensure no difference in bone mineral density among groups (n.s.). All specimens underwent femoral-sided ACLR with BTB autograft. Specimens subsequently underwent mechanical testing under monotonic loading conditions to failure. The load to failure and failure mechanism were recorded.

RESULTS

The mean pullout force (N) at time zero for each group was 309 ± 213 N, 518 ± 313 N, and 541 ± 267 N for 6 mm, 7 mm, and 8 mm biocomposite interference screw diameter, respectively (n.s.). One specimen in the 6 mm group, two specimens in the 7 mm group, and one specimen in the 8 mm group failed by screw pullout. The remainder in each group failed by graft failure (n.s.).

CONCLUSION

Biocomposite interference screw diameter did not have a significant influence on fixation pullout strength or failure mode following femoral tunnel fixation using BTB autograft at time zero. A 6 mm interference screw can improve preservation of native bone stock, increase potential for biologic healing, and decrease the risk of damage to the graft during insertion without significantly compromising fixation strength. This study supports the use of smaller 6 mm interference screw diameter options for femoral tunnel fixation in ACLR.

Clinical Reproducibility and Reliability of Lever Sign (Lelli's) Test for Acute ACL Tear Performed by Medical Students

BACKGROUND

Injuries to the anterior cruciate ligament (ACL) in sports are frequent in children and young adults participating in sporting activities involving rotational and pivoting movements. Magnetic resonance imaging is the most accurate diagnostic tool to detect an ACL tear. There are, however, a number of specialized tests available to assess ACL competency.

HYPOTHESIS

A novel test was described with extremely high clinical accuracy. The purpose of this study was to assess its clinical accuracy when performed by non-orthopedic providers, such as medical students.

METHODS

A cross-sectional study design was adopted, and two patients with an MRI-proven complete ACL tear were selected. One patient was thin, and the other was overweight, and both were examined by 100 medical students for both the injured and uninjured knee. The results for these exams were recorded, and a statistical analysis of the screening test was done to evaluate the new special test.

RESULTS

Our results were different from the ones found in the literature: we found the test to have a significantly lower performance in terms of sensitivity, specificity, and positive and negative likelihood ratios compared to the literature numbers.

CONCLUSION

The Lever sign (Lelli's) test loses clinical credibility and significance when performed by non-orthopedic providers or doctors, such as medical students in our study.

Is augmentation the best solution in partial anterior cruciate ligament tears? A literature systematic review and meta-analysis

Purpose

The appropriate management of partial anterior cruciate ligament (ACL) tears is still debated. There is a tendency in orthopedic clinical practice to prefer complete ACL reconstruction, while few surgeons perform ACL augmentation. The purpose of the present study is to evaluate the current evidence on the effectiveness of ACL augmentation compared with standard ACL reconstruction to assess whether ACL augmentation may be the treatment of choice in partial ACL injury.

Methods

According to PRISMA guidelines, literature research was performed in PubMed/Medline, Cochrane Library, Embase, Scopus, and Web of Science databases. A PICOS model was used, and a preliminary search resulted in 1101 articles. The methodological quality was assessed through ROBINS-I. A meta-analysis was conducted on postoperative Tegner, Lysholm scores and KT-1000 values between ACL augmentation and ACL reconstruction, and a p < 0.05 has been assumed as statistically significant. PROSPERO, ID: CRD42022343502.

Results

Seven papers were included. A total of 472 knees underwent ACL reconstruction, and 311 underwent ACL augmentation. A statistically significant discrepancy was found in the postoperative Tegner score in favor of ACL augmentation compared with ACL reconstruction (p < 0.05). Regarding the postoperative Lysholm score and KT-1000 measurement, no statistically significant difference was shown between ACL reconstruction and ACL augmentation (p > 0.05).

Conclusions

ACL augmentation has proved to be an effective and safe procedure and should be preferred to ACL reconstruction in partial ACL tears for the tendency to achieve better functional outcomes.

Morphometric MRI Evaluation of Three Autografts Used in Anterior Cruciate Ligament Reconstruction in Athletes

The purpose of the present study was to quantify the morphometric characteristics of three tendon autografts (hamstring tendons (HT), quadriceps tendon (QT), and patellar tendon (PT)) used in anterior cruciate ligament (ACL) reconstruction. For this purpose, knee magnetic resonance imaging (MRI) was obtained in 100 consecutive patients (50 males and 50 females) with an acute, isolated ACL tear without any other knee pathology were used. The level of the physical activity of the participants was determined using the Tegner scale. Measurements of the tendons' dimensions (PT and QT tendon length, perimeter, cross-sectional area (CSA), and maximum mediolateral and anteroposterior dimensions) were performed perpendicular to their long axes. Higher values were recorded as regards the mean perimeter and CSA of the QT in comparison with the PT and the HT (perimeter QT: 96.52 ± 30.43 mm vs. PT: 63.87 ± 8.45 mm, HT: 28.01 ± 3.73 mm, F = 404.629, p < 0.001; CSA QT: 231.88 ± 92.82 mm² vs. PT: 108.35 ± 28.98 mm², HT: 26.42 ± 7.15 mm², F = 342.415, p < 0.001). The length of the PT was shorter in comparison with the QT (53.1 ± 7.8 vs. 71.7 ± 8.6 mm, respectively, t = -11.243, p < 0.001). The three tendons showed significant differences in relation to sex, tendon type, and position as regards the perimeter, CSA, and the mediolateral dimensions but not for the maximum anteroposterior dimension.

Modern Treatment Principles for Multiligament Knee Injuries

Multiligament knee injuries are complex injuries that must be addressed with a comprehensive diagnostic workup and treatment plan. Multiligament injuries are commonly observed with concomitant meniscal, chondral, and neurovascular injuries, requiring a thorough clinical assessment and radiographic evaluation. Due to the higher failure rates associated with knee ligament repair following multiligament knee injury, the current literature favors single-stage anatomic knee reconstructions. Recent studies have also optimized graft sequencing and reconstruction tunnel orientation to prevent graft elongation and reduce the risk of tunnel convergence. In addition, anatomic-based ligament reconstruction techniques and the usage of suture anchors now allow for early postoperative knee motion without the risk of stretching out the graft. Rehabilitation following multiligament knee reconstruction should begin on postoperative day one and typically requires 9-12 months. The purpose of this article is to review the latest principles of the surgically relevant anatomy, biomechanics, evaluation, treatment, rehabilitation, and outcomes of multiligament knee injuries.

Is the Rotatory Knee Stability Immediately Decreased Following a Competitive Soccer Match?

Fatigue induced by soccer playing increases physical efforts, which might alter the transverse knee stability, a known factor that promotes knee injuries, particularly anterior cruciate ligament injury. Thereby, primarily, we aimed to determine whether rotatory knee stability decreases immediately following a competitive soccer match in amateur players. Furthermore, we assessed the role of the preferred and non-preferred limbs to kick a ball in rotatory knee stability and the correlation between performance parameters and rotatory knee stability. We hypothesized that the knee stability decreases immediately after a competitive soccer match in amateur players. Eight healthy amateur soccer players (aged 27.2 ± 4.7 years and with body mass index of 23.8 ± 1.2 kg m−2) were included immediately before and after a competitive soccer match. The rotatory knee stability was assessed in the preferred and non-preferred limbs through the acceleration and jerk of the pivot shift maneuver and by the internal knee rotation of a pivoting landing task. Two-way repeated-measures ANOVA for factors time (before and after the soccer match) and limb (preferred and non-preferred) and multiple comparisons were performed using α = 5%. There was a statistical significance for the main factor time in the acceleration (5.04 vs. 6.90 ms−2, Δ = 1.86 ms−2, p = 0.020, η2 = 0.331) and jerk (18.46 vs. 32.10 ms−2, Δ = 13.64 ms−2, p = 0.004, η2 = 0.456) of the pivot shift maneuver. Rotatory stability decreases following a competitive soccer match in amateur soccer players under fatigue. Both the acceleration and jerk during the pivot shift maneuver is increased without significant internal knee rotation changes during the pivoting landing task.

Global research in arthroscopy of the anterior cruciate ligament: A bibliometric and visualized study

Purpose

To carry out a bibliometric analysis of the scientific articles that address the topic of arthroscopy of the anterior cruciate ligament (ACL).

Methods

A bibliographic search of the original articles published in orthopedics journals indexed in the Web of Science database until 2020 was carried out. Evaluation of compliance with the inclusion criteria was carried out in the Rayyan web application. The Bibliometrix package in the R programming language and VOSviewer were used to perform the bibliometric analysis.

Results

2249 articles published in 87 journals were included. The first publication on the subject was in 1980, and the highest number of publications was registered in 2020 (151) (annual percentage growth rate of 5.7). Fu FH was the author with the highest number of published articles, and the institutional affiliation with the highest number of original articles was the University of Pittsburgh. The most cited article was the study by Peterson et al. (2000) and the journal with the highest number of publications was Arthroscopy: the journal of arthroscopic and related surgery. United States had the highest frequency of publications and the highest number of total citations received by country. It was found on the network that the largest number of published studies had keywords such as: injuries and follow-up, whereas, in the most recent articles, the most common terms were risk-factors and outcomes.

Conclusions

There is a sustained increase in scientific production on ACL arthroscopy among the world scientific community. Our results can be used for collaborative research purposes and by professionals seeking training in this topic.

Is 12 months enough to reach function after athletes' ACL reconstruction: a prospective longitudinal study

CONTEXT

Anterior Cruciate Ligament (ACL) injury is disabling in several sports because it causes knee instability and functional deficit. Usually, surgical treatments produce the best functional outcomes, however, sometimes they are not always able to fully restore stability and function.

OBJECTIVE

The objective of this study was to evaluate postural balance, muscle strength, and functional performance of young athletes with an ACL injury before and after ACL reconstruction.

DESIGN

This was a longitudinal observational prospective study.

METHOD

74 athletes, 60 men, and 14 women, aged between 16 and 45, divided into two groups: the Group-Lesion of ACL with 34 athletes (24.1 years) and the Group-Control with 40 athletes without ACL lesion (27.7 years old). All volunteers performed posturography, isokinetic dynamometry, and the Hop-Test. The ACL-Group was evaluated before and 12 months after the reconstruction and the control group was evaluated once.

RESULTS

The Postoperative ACL Group presented greater limb symmetry, 0.96 (± 0.12), than the preoperative ACL Group, 0.87 (± 0.17), p < 0.01 in the Hop-Test. In the posturography, the displacement area was smaller in the postoperative ACL Group, 19.85 (± 5.74), compared to the preoperative ACL Group, 24.20 (± 8.97), p < 0.01. In isokinetic dynamometry the torque peak was greater in the postoperative ACL Group, 0.91 (± 0.14), than in the preoperative ACL Group, 0.74 (± 0.15), p < 0.01.

CONCLUSION

The functional outcomes increased in ACL reconstruction athletes after 12 months, but not at the same level as in the Control Group. The result indicates an incomplete functional recovery, adaptive changes in postural control after injury, reconstruction, and return to sport.

Graft position at the femoral condyle affects knee mobility after posterior cruciate ligament replacement

BACKGROUND

In some cases posterior cruciate ligament (PCL) tears require surgical reconstruction. As the femoral footprint of the ligament is quite large, an ideal graft fixation position on the medial notch wall has not yet been identified. The aim of this study was to compare three different graft fixation positions within the anatomical footprint of the PCL and test it for posterior tibial translation at different knee flexion angles.

METHODS

In six human knee specimens a drawer test was simulated on a material testing machine by applying load on the tibia. At three different knee flexion angles (0°, 45°, 90°) knee mobility was examined with respect to tibial posterior translation and stiffness for the following conditions: intact ligaments, detached PCL, three different graft fixation positions on the femoral condyle.

RESULTS

Replacement of the PCL within its femoral footprint restored knee stability in terms of tibial posterior translation. Low graft position showed comparable drawer displacements to the intact condition for all knee flexion angles (p > 0.344). A higher graft position excessively reduced the posterior translation (p < 0.047) and resulted in a restricted knee mobility and a stiffer joint.

CONCLUSIONS

Graft fixation positions on the femoral condyle play a crucial role in post-operative knee mobility and joint functionality after PCL replacement. Even though all graft fixation positions were placed within the femoral footprint of a native PCL, only the lower position on the medial notch wall showed comparable posterior tibial translation to an intact PCL.

Experimental testing and finite element method analysis of the anterior cruciate ligament primary repair with internal brace augmentation

The internal brace (IB) technique is a promising treatment option for repairing the proximal rupture of the anterior cruciate ligament (ACL). This paper presents a biomechanical evaluation of the IB technique. Sixteen cadaveric sheep knees underwent monotonic tensile tests, cyclic loading, and passive flexion-extension testing. Data were compared in a series of eight control specimens with an intact ACL and eight repaired specimens where the ACL was cut and repaired using the IB. In parallel with the mechanical testing, finite element analysis (FEA) was performed to investigate the influence of IB loading on the femur-ACL-tibia complex (FATC). The 3D geometry of the FATC was reconstructed from CT scans of the sheep. The IB 3D model was integrated with the 3D FATC for FEA to obtain the femur-repaired ACL with IB - tibia complex (FRA-IB-TC) group. For the intact specimens, the mean (±SD) failure load in the tensile testing was 937 N (±192 N), while for the FRA-IB-TC specimens, it was 519 N (±52 N). The FRA-IB-TC remained biomechanically stable during the cyclic loading testing. The FEA demonstrated an increase in ACL stress to 24.59 MPa and displacement values of 0.391 mm. The IB construct exhibited shear and notch effects at the button-suture-bone fixation site. Testing on this sheep model allowed us a parametric analysis of the impact of the IB repair technique. However, the results will need to be confirmed in a human model. In conclusion, although the IB technique has biomechanical drawbacks, the mechanical properties of the technique are satisfactory.

A Criterion Based Rehabilitation Protocol for ACL Repair with Internal Brace Augmentation

The anterior cruciate ligament (ACL) is one of the main stabilizing structures of the knee and its rupture is a common injury in young active adults. ACL reconstruction has been the preferred operative management of an ACL rupture for several decades; however, success rates are variable. Recently, interest in arthroscopic primary repair of the ligament has increased. The repair is augmented with an Internal Brace (IB), which is an ultra-high strength suture tape that bridges the ligament. This technique protects the ligament during the healing and the ligament is encouraged to heal naturally, whilst not requiring any external braces. It acts as a stabiliser to permit early mobilization and optimise rehabilitation. As understanding of rehabilitation has progressed, there has been an increased focus on early weight-bearing and achieving full range of movement. While detailed criterion-based rehabilitation protocols exist for ACL reconstruction, this is not the case for ACL repair. The purpose of this commentary is to present a novel criterion-based rehabilitation protocol following ACL repair surgery augmented with an IB.

LEVEL OF EVIDENCE

V.

Accuracy of magnetic resonance imaging in predicting anterior cruciate ligament tear location and tear degree

Purpose

The purpose of this study is to evaluate the reliability of magnetic resonance imaging (MRI) in predicting the location of ACL tears in preoperative planning for anterior cruciate ligament (ACL) repair.

Methods

Thirty-four patients who underwent ACL repair were retrospectively analyzed to compare intraoperative arthroscopic findings with preoperative MRIs.

Results

For identifying type I tears, the sensitivity of MRI was 9.0% and the accuracy of MRI was 8.8%. There was moderate interrater agreement between MRI findings for tear location and tear degree.

Conclusion

MRI alone may not necessarily be accurate in identifying which ACL tears are amenable to repair.

Study design

Retrospective case series; Level of Evidence: IV.

Age-related changes in ACL morphology during skeletal growth and maturation are different between females and males

Despite a well-established role of anterior cruciate ligament (ACL) anatomy on its biomechanics, little is known on how ACL anatomy develops and changes during skeletal growth. We hypothesized that ACL size and orientation will change by age during skeletal growth and maturation with different trends in males vs females. Magnetic resonance images of 269 unique knees (3-18 years old; 51% female) were used to measure ACL length, cross-sectional area, length-to-cross-sectional area ratio, and elevation angles. In both males and females, ACLs became longer, thicker, and more vertical in sagittal and coronal planes by increasing age (R2  > 0.2; P < .001 for all associations). ACL cross-sectional area-to-length ratio increased by age only in males (R2  = 0.06; P = .003). Despite similar ACL sizes between males and females at early age, adolescent males had significantly longer and thicker ACLs compared to the age-matched females (P < .05). There were no sex differences in ACL elevation angles (P > .2) except for larger coronal elevation in 7 to 10 years old females compared to age-matched males (P = .012). Observed changes in ACL cross-sectional area-to-length ratio indicate that age- and sex-dependent changes in ACL size are not homogenous. The trends seen in normalized ACL size measurements suggest that unlike ACL cross-sectional area, ACL length is primarily controlled by body size. Smaller ACLs and lower cross-sectional growth rates observed in females may be contributing factors to the higher risk of ACL injuries in females. Further investigations are required to identify the intrinsic and extrinsic factors responsible for these discrepancies.

Analysis of Posterior Tibial Slope as Risk Factor to Anterior Cruciate Ligament Tear

Objective  The objective of the present study was to evaluate the relationship between patients with anterior cruciate ligament (ACL) injury by indirect trauma and increased posterior tibial inclination.

Methods  Retrospective study, performed by analysis of medical records and digital radiographs of patients, present in a database of a tertiary orthopedic hospital. The sample consisted of two groups, the first group consisting of patients diagnosed with ACL injury by indirect trauma, and a control group matched by age.

Results  Each group consisted of 275 patients, whose measurements of posterior tibial inclination were measured by three specialists. It was observed that the group of patients with ACL lesion presented a significantly higher tibial slope (in degrees) than the control group in the total sample and in the subsamples stratified by gender. The best cutoff point for the first group was identified as a posterior tibial inclination ≥ 8°, achieving a sensitivity of 63.3% and a specificity of 62.5%. The first group also had a tibial slope ratio ≥ 8° (63.3%), significantly higher than the control group (37.5%), with an odds ratio of 2.8.

Conclusion  It was concluded that the increase of the posterior tibial inclination is associated with an increased risk for injury of the ACL by indirect trauma, mainly for values ≥ 8°.

Immunohistochemical analysis of sensory corpuscles in human transplants of the anterior cruciate ligament

Background

Sensory nerve endings in ligaments play an important role for the proprioceptive function. Clinical trials show that the sense of body position does not fully recover in the knee joint after reconstructive surgery of the ruptured anterior cruciate ligament. The aim of this study is to identify sensory corpuscles in autogenous and allogenous transplants of the ligament and to compare their quantity between the used allografts and autografts.

Methods

Thirty-three patients were included in this study. Three patellar tendon allografts, 14 patellar tendon autografts and 12 semitendinosus autografts were harvested during revision surgery after traumatic rerupture of the graft. The control consisted of 4 healthy anterior cruciate ligaments after fresh rupture. After haematoxylin staining, immunohistochemical analysis was performed using antibodies against S100, p75 and PGP9.5. Microscopical examination was carried out, and the number of mechanoreceptors was counted. Statistical analysis was performed using the Mann-Whitney U test.

Results

Two types of mechanoreceptors were identified in each graft: Ruffini corpuscles and free nerve endings. The number of Ruffini corpuscles per square centimeter was the highest in the control. Comparing the grafts, the highest number of receptors could be detected in the semitendinosus autograft. The amount of free nerve endings was higher in the semitendinosus and patellar tendon autografts than in the control; the allografts showed the lowest number of receptors. With increasing time after reconstruction, the number of both types of receptors showed a decrease in the semitendinosus graft, whereas it increased in the patellar tendon graft and allograft. The number of mechanoreceptors in the semitendinosus and patellar tendon graft decreased over time after graft-failure, whereas it increased slightly in the allograft.

Conclusion

This study was the first to identify mechanoreceptors in human transplants of the anterior cruciate ligament. The partial increase in the number of receptors over time after reconstruction could indicate a reinnervation of the grafts.

Predicting the peroneus longus tendon autograft size in ACL reconstruction by using anthropometric parameters: A study in South Sulawesi population

Introduction

Some literature use peroneus longus tendon (PLT) as the alternative to anterior cruciate ligament (ACL) reconstruction to overcome inadequate autograft size potential risk by using hamstring tendon (HT) autograft. Among the available methods to predict PLT measurements, anthropometric parameters are one of the most accessible and feasible methods. The objective of this prospective study was to predict the PLT autograft sizes in single bundle ACL reconstruction by using preoperative anthropometric measurement.

Method

Anthropometric parameters, including age, gender, height, weight, body mass index (BMI), true leg length (TLL), shank circumference and shank length of 20 patients with primary ACL reconstruction was measured before surgery. Univariate analysis, independent-sample t-test, Pearson correlation test, and logistic regression to evaluate the influence of these anthropometric variables on the diameter and length of the PLT autograft obtained.

Result

Pearson correlation test has shown that body weight and height correlates to PLT length and diameter also autograft's length and diameter significantly (p < 0.05). The linear regression analysis showed that height, weight, TLL and shank length were signifcantly related to autograft diameter. While height and TLL were significantly related to autograft length.

Conclusion

Height, weight, TLL and shank length can use to predict PLT autograft diameter. While height and TLL can use to predict PLT autograft length.

•

It is important to estimate tendon graft size prior to ACL reconstruction surgery.

•

Preoperative anthropometric measurement is a good method to predict PLT autograft size.

•

Height is a good predictor of the PLT autograft diameter and length.

•

Patient less than 153 cm in height, high risk for having in adequate graft size.

Characterization of Post-Traumatic Osteoarthritis in Rats Following Anterior Cruciate Ligament Rupture by Non-Invasive Knee Injury (NIKI)

Small animal models are essential for studying anterior cruciate ligament (ACL) injury, one of the leading risk factors for post-traumatic osteoarthritis (PTOA). Non-surgical models of ACL rupture have recently surged as a new tool to study PTOA, as they circumvent the confounding effects of surgical disruption of the joint. These models primarily have been explored in mice and rabbits, but are relatively understudied in rats. The purpose of this work was to establish a non-invasive, mechanical overload model of ACL rupture in the rat and to study the disease pathogenesis following the injury. ACL rupture was induced via non-invasive tibial compression in Lewis rats. Disease state was characterized for 4 months after ACL rupture via histology, computed tomography, and biomarker capture from the synovial fluid. The non-invasive knee injury (NIKI) model created consistent ACL ruptures without direct damage to other tissues and resulted in conventional OA pathology. NIKI knees exhibited structural changes as early as 4 weeks post-injury, including regional structural changes to cartilage, chondrocyte and cartilage disorganization, changes to the bone architecture, synovial hyperplasia, and the increased presence of biomarkers of cartilage fragmentation and pro-inflammatory cytokines. These results suggest that this model can be a valuable tool to study PTOA. By establishing the fundamental pathogenesis of this injury, additional opportunities are created to evaluate unique contributing factors and potential therapeutic interventions for this disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:356-367, 2020.

Effects of cartilage-targeting moieties on nanoparticle biodistribution in healthy and osteoarthritic joints

Understanding intra-articular biodistribution is imperative as candidate osteoarthritis (OA) drugs become increasingly site-specific. Cartilage has been identified as opportunistic for therapeutic intervention, but poses numerous barriers to drug delivery. To facilitate drug delivery to cartilage, nanoscale vehicles have been designed with different features that target the tissue's matrix. However, it is unclear if these targeting strategies are influenced by OA and the associated structural changes that occur in cartilage. The goal of this work was to study the effectiveness of different cartilage-targeting nanomaterials with respect to cartilage localization and retention, and to determine how these outcomes change in OA. To address these questions, a nanoparticle (NP) system was developed, and the formulation was tuned to possess three distinct cartilage-targeting strategies: (1) passive targeting cationic NPs for electrostatic attraction to cartilage, (2) active targeting NPs with binding peptides for collagen type II, and (3) untargeted neutrally-charged NPs. Ex vivo analyses with bovine cartilage explants demonstrated that targeting strategies significantly improved NP associations with both healthy and OA-like cartilage. In vivo studies with collagenase-induced OA in rats revealed that disease state influenced joint biodistribution for all three NP formulations. Importantly, the extent of cartilage accumulation for each NP system was affected by disease differently; with active NPs, but not passive NPs, cartilage accumulation was increased in OA relative to healthy knees. Together, this work suggests that NPs can be strategically designed for site-specific OA drug delivery, but the biodistribution of the NPs are influenced by the disease conditions into which they are delivered. STATEMENT OF SIGNIFICANCE: As emerging drugs for osteoarthritis are becoming increasingly site-specific, the need for targeted intra-articular drug delivery has evolved. To improve drug delivery to cartilage, targeting strategies for nanomaterials have been developed, but the manner in which these targeted systems accumulate at different sites within the joint remains poorly understood. Moreover, it is unclear how nanomaterial-tissue interactions change in osteoarthritic conditions, as tissue structure and composition change after disease onset. By understanding how nanomaterials distribute within healthy and disease joints, we can advance targeted drug delivery strategies and improve therapeutic outcomes for emerging drugs.

Fixation of the Anterior Ligament Graft at the Tibial Pole: Biomechanical Analysis of Three Methods

Objective  Comparative biomechanical analysis of tibial fixation strength for ligament reconstruction with interference screw compared with screw post and washer, and compared with the associated fixation of both methods (hybrid fixation).

Method  A total of 54 specimens were used (porcine tibias and bovine flexor digital tendons), which were divided into three groups with fixation types similar to those used in anterior cruciate ligament (ACL) reconstruction: 1) fixation with interference screw; 2) fixation with screw post and toothed washer over knot and suture strand; and )- fixation with screw post and washer combined with interference screw (hybrid fixation). The analyses were performed through pull-out biomechanical tensile tests to determine the stiffness and load to system failure (yield load).

Results  The hybrid fixation group presented a significantly higher final stiffness (59.10 ± 3.45 N/mm) in comparison to the other groups ( p  < 0.05) and a higher yield load (581.34 ± 33.48 N) compared to the interference screw group ( p  < 0.05).

Conclusion  Hybrid fixation had biomechanical advantages over the bovine digital flexor graft fixation system in swine tibia during tensile tests.

Mechanical properties of a hierarchical electrospun scaffold for ovine anterior cruciate ligament replacement

The anterior cruciate ligament (ACL) acts to stabilize the knee and prevent excessive motion of the tibia relative to the femur. Tears of the ACL are common and can result in pain and damage to surrounding tissues. Thus a torn ACL is often surgically replaced with an autograft or allograft material. Drawbacks to clinically available ACL grafts motivate the development of a tissue engineered ACL replacement. Our group has previously developed a polycaprolactone electrospun scaffold that mimics the hierarchical structure of the ACL. The goal of this study was to investigate the mechanical properties of the electrospun scaffold as an ACL replacement. Scaffold mechanical properties were assessed prior to implantation via stress relaxation and pull to failure testing. Following in vitro characterization, electrospun scaffolds and soft tissue grafts were implanted into ovine cadaver stifle joints as ACL replacements. Stifle joints with ACL replacements were tested via a simulated anterior drawer test as well as in situ stress relaxation and pull to failure tests and compared to stifle joints with the native ACL intact. Prior to implantation the scaffold matched the native ovine ACL well in the range of functional strains as evidenced by stress relaxation measures and the toe region stiffness. After implantation the scaffold was more similar to the native ACL than the soft tissue graft, particularly when it came to reducing joint laxity and matching stress relaxation measures. These results demonstrate that the electrospun scaffold has the potential to be a suitable material for ACL replacement. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:421-430, 2019.

Passive anterior tibia translation in anterior cruciate ligament-injured, anterior cruciate ligament-reconstructed and healthy knees: a systematic review

Abstract

Anterior tibia translation (ATT) is mainly prevented by the anterior cruciate ligament. Passive ATT tests are commonly used to diagnose an anterior cruciate ligament (ACL) injury, to select patients for an ACL reconstruction (ACLR), and as an outcome measure after an ACLR. The aim of this review was to present an overview of possible factors determining ATT. A second purpose was to give a summary of the ATT measured in the literature in healthy, ACL-injured and ACLR knees and a comparison between those groups. A literature search was conducted with PubMed. Inclusion criteria were full-text primary studies published in English between January 2006 and October 2016. Studies included reported ATT in explicit data in healthy as well as ACL-injured or ACLR knees or in ACL-injured as well as ACLR knees. Sixty-one articles met inclusion criteria. Two articles measured the ATT in healthy as well as ACL-injured knees, 51 in ACL-injured as well as in ACLR knees, three in ACLR as well as in healthy knees and three in healthy, ACL-injured and ACLR knees. A difference in ATT is found between healthy, contralateral, ACLR and ACL-injured knees and between chronic and acute ACL injury. Graft choices and intra-articular injuries are factors which could affect the ATT. The mean ATT was lowest to highest in ACLR knees using a bone–patella tendon–bone autograft, ACLR knees using a hamstring autograft, contralateral healthy knees, healthy knees, ACLR knees with an allograft and ACL-injured knees. Factors which could affect the ATT are graft choice, ACL injury or reconstruction, intra-articular injuries and whether an ACL injury is chronic or acute. Comparison of ATT between studies should be taken with caution as a high number of different measurement methods are used. To be able to compare studies, more consistency in measuring devices used should be introduced to measuring ATT. The clinical relevance is that an autograft ACLR might give better results than an allograft ACLR as knee laxity is greater when using an allograft tendon.

Level of evidence

III.

Knee Extensors Muscle Plasticity Over a 5-Years Rehabilitation Process After Open Knee Surgery

We investigated molecular and cellular parameters which set metabolic and mechanical functioning of knee extensor muscles in the operated and contralateral control leg of 9 patients with a chronically insufficient anterior cruciate ligament (ACL; 26.6 ± 8.3 years, 8 males, 1 female) after open reconstructive surgery (week 0), after ambulant physiotherapy under cast immobilization (week 9), succeeding rehabilitation training (up to week 26), and subsequent voluntary physical activity (week 260). Clinical indices of knee function in the operated leg were improved at 52 weeks and remained at a comparable level at week 260. CSA of the quadriceps (-18%), MCSA of muscle fibers (-24%), and capillary-to-fiber ratio (-24%) in m. vastus lateralis from the ACL insufficient leg were lower at week 0 than reference values in the contralateral leg at week 260. Slow type fiber percentage (-35%) and mitochondrial volume density (-39%) were reduced in m. vastus lateralis from the operated leg at weeks 9 and 26. Composition alterations in the operated leg exceeded those in the contralateral leg and, with the exception of the volume density of subsarcolemmal mitochondria, returned to the reference levels at week 260. Leg-specific deterioration of metabolic characteristics in the vasti from the operated leg was reflected by the down-regulation of mitochondrial respiration complex I-III markers (-41-57%) at week 9. After rehabilitation training at week 26, the specific Y397 phosphorylation of focal adhesion kinase (FAK), which is a proxy for mechano-regulation, was elevated by 71% in the operated leg but not in the contralateral leg, which had performed strengthening type exercise during ambulant physiotherapy. Total FAK protein and Y397 phosphorylation levels were lowered in both legs at week 26 resulting in positive correlations with mitochondrial volume densities and mitochondrial protein levels. The findings emphasize that a loss of mechanical and metabolic characteristics in knee extensor muscle remains detectable years after untreated ACL rupture, which may be aggravated in the post-operative phase by the deterioration of slow-oxidative characteristics after reconstruction due to insufficient load-bearing muscle activity. The reestablishment of muscle composition subsequent to years of voluntary physical activity reinforces that slow-to-fast fiber transformation is reversible in humans.

The clinical relevance of PCL index on the reconstruction of anterior cruciate ligament with hamstring tendon autograft

The posterior cruciate ligament index (PCL index) has been reported as a diagnostic and prognostic marker for anterior cruciate ligament (ACL) reconstruction. The clinical relevance of PCL index on the reconstruction of ACL with hamstring tendon autograft has not been described in the literature. The objective of this study is to evaluate the importance of the PCL index as a marker of anatomic reconstruction and of functional improvement of patients undergoing ACL reconstruction with HT autograft. Twenty-four patients were submitted to ACL reconstruction with HT autograft. The PCL index was assessed by magnetic resonance imaging before and after surgery. The functional evaluation was performed through the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form© and Knee Society Knee Scoring System© (IKS). Patients presented a significant positive variation of the PCL index, IKDC and IKS scores. There is no significant correlation between PCL index variation and IKDC and IKS scores (p > 0.05). Unlike other studies reporting a relationship between the PCL index, control of rotational kinematics, and functional improvement in patients undergoing ACL reconstruction with bone-patellar tendon-bone autograft, this study does not demonstrate this association. There is evidence in this study to show that the PCL index may be used as an anatomic reconstructive marker of ACL but not to predict the clinical outcome in this type of reconstruction.

A Method of Accurate Bone Tunnel Placement for Anterior Cruciate Ligament Reconstruction Based on 3-Dimensional Printing Technology: A Cadaveric Study

PURPOSE

To explore a method of bone tunnel placement for anterior cruciate ligament (ACL) reconstruction based on 3-dimensional (3D) printing technology and to assess its accuracy.

METHODS

Twenty human cadaveric knees were scanned by thin-layer computed tomography (CT). To obtain data on bones used to establish a knee joint model by computer software, customized bone anchors were installed before CT. The reference point was determined at the femoral and tibial footprint areas of the ACL. The site and direction of the bone tunnels of the femur and tibia were designed and calibrated on the knee joint model according to the reference point. The resin template was designed and printed by 3D printing. Placement of the bone tunnels was accomplished by use of templates, and the cadaveric knees were scanned again to compare the concordance of the internal opening of the bone tunnels and reference points.

RESULTS

The twenty 3D printing templates were designed and printed successfully. CT data analysis between the planned and actual drilled tunnel positions showed mean deviations of 0.57 mm (range, 0-1.5 mm; standard deviation, 0.42 mm) at the femur and 0.58 mm (range, 0-1.5 mm; standard deviation, 0.47 mm) at the tibia.

CONCLUSIONS

The accuracy of bone tunnel placement for ACL reconstruction in cadaveric adult knees based on 3D printing technology is high.

CLINICAL RELEVANCE

This method can improve the accuracy of bone tunnel placement for ACL reconstruction in clinical sports medicine.

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.