Current concepts in ACL Injuries

Effect of Age and Sex on Anterior Cruciate Ligament Functional Tests Approximately 6 Months After Anterior Cruciate Ligament Reconstruction

Purpose

To examine age- and sex-related differences in postoperative functional outcomes at approximately 6 months after anterior cruciate ligament reconstruction (ACLR).

Methods

In this study, patients who underwent primary ACLR performed a series of return-to-sport functional tests at 5 to 8 months after surgery. Functional tests included strength tests (knee extensors, knee flexors, hip abductors, and hip extensors), a balance test (Y-balance composite score), and hop tests (single, triple, crossover, and 6-m timed hop tests). Limb symmetry was calculated to compare the reconstructed limb with the uninvolved limb. A 2-way multivariate analysis of covariance was used, and effect size was calculated for data analysis.

Results

A total of 176 subjects were included in this study. There were no significant interaction between age and sex on return-to-sport functional tests after ACLR. Also, no main effects of age and sex on return-to-sport functional tests were found in our data.

Conclusions

Age and sex do not significantly affect functional test performance after ACLR 6 months postoperatively.

Level of Evidence

Level III, retrospective review of prospective cohort study.

Relative Telomere Length in Blood Leukocytes of Patients with Anterior Cruciate Ligament Injury: A Pilot Study

Introduction: Anterior cruciate ligament (ACL) tear is the most common knee ligament injury, especially in athletes. The objective of this study was to investigate relative telomere length (RTL) in blood leukocytes of patients with ACL injury compared with that of controls.

Materials and Methods: A total of 187 subjects were invited to participate in this study. Ninety-two patients with clinically diagnosed ACL rupture were enrolled. Ninety-five age and gender-matched healthy controls were also recruited. Blood leukocyte RTL were analysed using quantitative real-time polymerase chain reaction.

Results: Patients with ACL rupture had significantly longer relative telomere length than healthy controls (P=0.002). The patients with ACL rupture were classified into two groups according to the sport history of patients which are contact sports and non-contact sports. RTL in patients with non-contact sports was significantly greater than those with contact sports (P=0.006). Moreover, RTL was inversely correlated with body mass index of patients with ACL injury (r=-0.34, P=0.001). Logistic regression analysis indicated that long RTL was associated with a higher risk of ACL rupture.

Conclusion: The present study showed that subjects with ACL rupture had significantly greater telomere length compared with their age and gender-matched controls. This finding may result from the increases in physical activity and overexpression of telomerase which acts as a protective mechanism against ACL injury. RTL in blood leukocytes is associated with a risk of ACL rupture.

Direct Visualization of Suspensory Fixation Deployment in Knee Ligament Reconstructions Without Fluoroscopic Imaging

The authors describe a technique for visualizing the deployment of femoral suspensory fixation during ligament reconstructions that avoids the need for intraoperative fluoroscopic radiographs. Many surgeons currently use intraoperative fluoroscopic radiographs to confirm satisfactory deployment of the suspensory button on the femur; however, this technique involves prolonged surgical time, additional costs, and radiation exposure to the surgical team and patient. The authors' technique uses novel leg and camera positioning to allow for direct visualization of the button deployment. This technique can greatly improve operating room efficiency, save money, and decrease radiation exposure during surgery. [Orthopedics. 2018; 41(4):e587-e590.].

Relation between peak knee flexion angle and knee ankle kinetics in single-leg jump landing from running: a pilot study on male handball players to prevent ACL injury

OBJECTIVES

The relationship between knee kinematics and knee-ankle kinetics during the landing phase of single leg jumping has been widely studied to identify proper strategies for preventing non-contact ACL injury. However, there is a lack of study on knee-ankle kinetics at peak knee flexion angle during jumping from running. Hence, the purpose of this study is to establish the relationship between peak knee flexion angle, knee extension moment, ankle plantar flexion moment and ground reaction force in handball players in order to protect ACL from excessive stress during single leg jumping. In addition, the study also clarifies the role of calf muscles in relieving part of ACL stresses with different knee flexion angles during landing.

METHODS

Fifteen active male elite handball players of Saudi Arabia have participated in this study (Age = 22.6 ± 3.5years, Height = 182 ± 3.7 cm, Weight = 87.5 ± 10.2 kg). The players performed three successful landings of single-leg jump following running a fixed distance of about 450cm. The data were collected using a 3D motion capture and analysis system (VICON).

RESULTS

Pearson product moment correlation coefficients showed that greater peak knee flexion angle is related significantly to both lesser knee extension moment (r = -.623, P = .013) and vertical component of ground reaction force (VGRF) (r = -.688, P = .005) in landing phase. Moreover, increasing the peak knee flexion angle in landing phase tends to increase the ankle plantar flexion moment significantly (r = .832, P = .000).

CONCLUSION

With an increase of the peak knee flexion angle during single leg jump landing from running, there would be less knee extension moment, low impact force and more plantar flexion moment. As such, the clinical implication of this study is that there may be a possible protective mechanism by increasing the knee flexion angle during landing phase, which tends to protect the ACL from vigorous strain and injuries.

Incarceration of the intermeniscal ligament in tibial eminence injury: a block to closed reduction identified using MRI

Tibial eminence fractures are a relatively uncommon injury, but most frequently occur in children and adolescents with open physes. Entrapment of the intermeniscal ligament or the meniscus itself can occur in the setting of a tibial eminence fracture and when present, poses a significant obstacle to successful closed or surgical reduction. Identification of these entrapped structures on preoperative imaging may be helpful to the physicians caring for these patients and assist with preoperative planning. We present a case of a 13-year-old male who sustained a tibial eminence fracture while playing football. Review by the orthopedic surgeon identified entrapment of the intermeniscal ligament. Subsequently, a closed reduction attempt under anesthesia prior to surgery was unsuccessful and arthroscopy was needed to remove the entrapped intermeniscal ligament and reduce the tibial eminence fracture. Pre-operative knowledge of entrapped soft tissue structures under the fracture plane, particularly the meniscus and intermeniscal ligament, provides the surgeon with valuable insight as to how to best counsel patients on the success of treatment options, how to best prepare for operative treatment, and can guide the surgeon during open reduction to maximize treatment success.

Neuromuscular electrical stimulation induces beneficial adaptations in the extracellular matrix of quadriceps muscle after anterior cruciate ligament transection of rats

OBJECTIVE

The aim of this study was to assess the effect of neuromuscular electrical stimulation (NMES) on the extracellular matrix remodeling of the quadriceps muscle after anterior cruciate ligament (ACL) transection in rats. The hypothesis of this study was that ACL transection would induce maladaptive modifications in the extracellular matrix through the increase in connective tissue (CT) accumulation and net degradation of type IV collagen of the quadriceps muscle. In addition, clinical-like NMES, applied to the quadriceps muscle immediately after the ACL transection, would reduce the accumulation of the CT content and net degradation of type IV collagen.

DESIGN

Wistar male rats were randomized into five different groups: ACL (surgery and ACL transection), Sham (surgery without ACL transection), ACLES (surgery, ACL transection, and NMES), ShamES (surgery without ACL transection, but NMES), and Control (intact animals). The vastus medialis, rectus femoris, and vastus lateralis muscles of the quadriceps were harvested 1, 2, 3, 7, and 15 days after surgery. Matrix metalloproteinase-2 (MMP-2) (messenger RNA [mRNA] levels and activity), collagen IV (mRNA and protein levels), and CT density were assessed.

RESULTS

The ACL transection increased the CT content and MMP-2 mRNA levels and decreased collagen IV mRNA and protein levels. NMES minimized the CT density in all muscles and reduced the MMP-2 mRNA levels mainly in the vastus lateralis muscle at 7 days. Moreover, type IV collagen mRNA levels were increased in all muscles at 7 days, as was the protein level only at 15 days, in the NMES groups.

CONCLUSIONS

This study showed that ACL transection increases CT content and MMP-2 mRNA levels and induces rapid changes in basement membranes, causing net degradation of type IV collagen during the first 2 wks after ACL injury. Furthermore, clinical-like NMES minimized the accumulation of CT density, regulated the MMP-2 mRNA levels, and increased both type IV collagen mRNA and protein levels.

Quadriceps muscle atrophy after anterior cruciate ligament transection involves increased mRNA levels of atrogin-1, muscle ring finger 1, and myostatin

OBJECTIVE

The aim of this study was to assess the mRNA levels of atrogin-1, muscle ring finger 1, and myostatin in rat quadriceps after anterior cruciate ligament (ACL) transection.

DESIGN

Wistar rats were randomized into three different groups: ACL (surgery and ACL transection), sham (surgery without ACL transection), and control. Vastus medialis, rectus femoris, and vastus lateralis muscles were harvested at 1, 2, 3, 7, and 15 days after ACL transection. The mRNA levels of atrogin-1, muscle ring finger 1, and myostatin, as well as the ubiquitinated protein content, muscle mass, and cross-sectional area of the muscle fibers, were evaluated.

RESULTS

Elevated levels of atrogin-1, muscle ring finger 1, and myostatin mRNA were detected in all tested muscles at most time points. The ubiquitinated protein content was increased at 3 days in the ACL and sham groups. The muscle mass of the ACL group was reduced at 3, 7, and 15 days (vastus lateralis and vastus medialis) and at 7 and 15 days (rectus femoris), whereas it was reduced in the sham group at 3 and 7 days (vastus lateralis and vastus medialis) and at 7 days (rectus femoris). The cross-sectional area of vastus medialis was reduced at 3, 7, and 15 days in the ACL group and at 3 and 7 days in the sham group. The cross-sectional area of the vastus lateralis was reduced at 7 and 15 days in the ACL group and at 7 days in the sham group. Whereas muscle mass and cross-sectional area recovery was noted in the sham group, no recovery was observed in the ACL group.

CONCLUSIONS

Quadriceps atrophy after ACL transection involves increased levels of myostatin, atrogin-1, and muscle ring finger 1 mRNA and the accumulation of ubiquitinated protein.

Muscle strength and hop performance criteria prior to return to sports after ACL reconstruction

PURPOSE

The purpose of this article is to present recommendations for new muscle strength and hop performance criteria prior to a return to sports after anterior cruciate ligament (ACL) reconstruction.

METHODS

A search was made of relevant literature relating to muscle function, self-reported questionnaires on symptoms, function and knee-related quality of life, as well as the rate of re-injury, the rate of return to sports and the development of osteoarthritis after ACL reconstruction. The literature was reviewed and discussed by the European Board of Sports Rehabilitation in order to reach consensus on criteria for muscle strength and hop performance prior to a return to sports.

RESULTS

The majority of athletes that sustain an (ACL) injury do not successfully return to their pre-injury sport, even though most athletes achieve what is considered to be acceptable muscle function. On self-reported questionnaires, the athletes report high ratings for fear of re-injury, low ratings for their knee function during sports and low ratings for their knee-related quality of life.

CONCLUSION

The conclusion is that the muscle function tests that are commonly used are not demanding enough or not sensitive enough to identify differences between injured and non-injured sides. Recommendations for new criteria are given for the sports medicine community to consider, before allowing an athlete to return to sports after an ACL reconstruction.