Physiological anterior laxity in healthy young females: the effect of knee hyperextension and dominance

Clinico-Radiological Correlation Between Anterior Cruciate Ligament Deficiency and Hyperextension of the Knee Joint: A Prospective Study

INTRODUCTION

The anterior cruciate ligament (ACL) primarily restricts anterior sliding of the tibia over the fixed femur, thereby also postulating to prevent hyperextension of the knee joint. The main objective of our study was to identify the role of the ACL in the prevention of knee hyperextension and to quantify the amount of hyperextension caused by an ACL tear, apart from its well-established role in the prevention of anterior tibial translation on the fixed femur.

METHODS

 This prospective study was conducted in a tertiary care hospital. Eighty patients with unilateral ACL tears were assessed clinico-radiologically in the preoperative period to quantify the knee hyperextension, which was then compared with the uninjured contralateral knee of the same patient. Posterior tibial slope and notch width index were also assessed to rule out bias in our study.

RESULTS

The mean age of patients in our study was 27.3 years. Out of 80 patients, 70 were male and 10 were female. The Pearson coefficient for clinically and radiologically assessed hyperextension was 0.919 (p-value 0.001) and 0.910 (p-value 0.001), respectively. Posterior tibial slope and notch width index assessment showed Pearson coefficients of -0.018 (p-value 0.887) and -0.068 (p-value 0.547), respectively.

CONCLUSION

Anterior cruciate ligament complete tear or deficiency produces knee hyperextension, which varies from patient to patient. Though the amount of hyperextension produced is mild (less than five degrees in most patients), it can cause a significant amount of knee instability. Hence, correction of knee hyperextension is crucial while performing ACL reconstruction.

Alteration in ACL loading after total and partial medial meniscectomy

Anterior cruciate ligament (ACL) injuries are often caused by high impact loadings during competitive sports but may also happen during regular daily activities due to tissue degeneration or altered mechanics after a previous knee injury or surgery such as meniscectomy. Most existing research on ACL injury has focused on impact loading scenarios or the consequence of ACL injury on meniscus. The objective of the present study was to investigate the effects of varying degrees of medial meniscectomy on the mechanics of intact ACL by performing a poromechanical finite element analysis under moderate creep loadings. Four clinical scenarios with 25%, 50%, 75% and total medial meniscectomy were compared with the intact knee finite element model. Our results suggested that different medial meniscal resections may increase, at different extents, the knee laxity and peak tensile stress in the ACL, potentially leading to collagen fiber fatigue tearing and altered mechanobiology under normal joint loadings. Interestingly, the ACL stress actually increased during early knee creep (~ 3 min) before it reached an equilibrium. In addition, meniscectomy accelerated ACL stress reduction during knee creep, transferred more loading to tibial cartilage, increased contact pressure, and shifted the contact center posteriorly. This study may contribute to a better understanding of the interaction of meniscectomy and ACL integrity during daily loadings.

Positional MR imaging of normal and injured knees

OBJECTIVES

This study uses a practical positional MRI protocol to evaluate tibiofemoral translation and rotation in normal and injured knees.

METHODS

Following ethics approval, positional knee MRI of both knees was performed at 35° flexion, extension, and hyperextension in 34 normal subjects (mean age 31.1 ± 10 years) and 51 knee injury patients (mean age 36.4 ± 11.5 years, ACL tear n = 23, non-ACL injury n = 28). At each position, tibiofemoral translation and rotation were measured.

RESULTS

Normal knees showed 8.1 ± 3.3° external tibial rotation (i.e., compatible with physiological screw home mechanism) in hyperextension. The unaffected knee of ACL tear patients showed increased tibial anterior translation laterally (p = 0.005) and decreased external rotation (p = 0.002) in hyperextension compared to normal knees. ACL-tear knees had increased tibial anterior translation laterally (p < 0.001) and decreased external rotation (p < 0.001) compared to normal knees. Applying normal thresholds, fifteen (65%) of 23 ACL knees had excessive tibial anterior translation laterally while 17 (74%) had limited external rotation. None (0%) of 28 non-ACL-injured knees had excessive tibial anterior translation laterally while 13 (46%) had limited external rotation. Multidirectional malalignment was much more common in ACL-tear knees.

CONCLUSIONS

Positional MRI shows (a) physiological tibiofemoral movement in normal knees, (b) aberrant tibiofemoral alignment in the unaffected knee of ACL tear patients, and (c) a high frequency of abnormal tibiofemoral malalignment in injured knees which was more frequent, more pronounced, more multidirectional, and of a different pattern in ACL-tear knees than non-ACL-injured knees.

KEY POINTS

• Positional MRI shows physiological tibiofemoral translation and rotation in normal knees. • Positional MRI shows a different pattern of tibiofemoral alignment in the unaffected knee of ACL tear patients compared to normal control knees. • Positional MRI shows a high prevalence of abnormal tibiofemoral alignment in injured knees, which is more frequent and pronounced in ACL-tear knees than in ACL-intact injured knees.

Dynamic Taping Improves Landing Biomechanics in Young Volleyball Athletes

Poor landing biomechanics such as hip adduction, internal rotation, and knee valgus have been recognized as modifiable risk factors of anterior cruciate ligament (ACL) injury. Dynamic taping is a newly developed technique with better elasticity and extensibility, which could change the landing biomechanics. The purpose of this study was to identify whether dynamic taping could improve lower limb biomechanics in athletes. Forty-two high school volleyball athletes (21 males and 21 females) participated in the study. Biomechanical properties, including the landing error scoring system (LESS) and anterior-posterior knee laxity, were evaluated before and after the application of dynamic tape while athletes performed the jump-landing task. As a result, we found that dynamic tape significantly reduced the faulty landing strategy by an average of 0.64 errors in all volleyball athletes. The effect induced by dynamic tape was more prominent in female athletes and high-risk athletes (1.1 errors). Furthermore, the application of dynamic tape improved anterior-posterior knee laxity, especially in female athletes (p < 0.001). In conclusion, we found that dynamic tape provided a short-term, passive, and clinically significant means to normalize inadequate biomechanics during landing in athlete groups, which could have a protective effect and further alleviate the risk of ACL injury.

Sex and Limb Differences in Lower Extremity Alignment and Kinematics during Drop Vertical Jumps

Sex and limb differences in lower extremity alignments (LEAs) and dynamic lower extremity kinematics (LEKs) during a drop vertical jump were investigated in participants of Korean ethnicity. One hundred healthy males and females participated in a drop vertical jump, and LEAs and LEKs were determined in dominant and non-dominant limbs. A 2-by-2 mixed model MANOVA was performed to compare LEAs and joint kinematics between sexes and limbs (dominant vs. non-dominant). Compared with males, females possessed a significantly greater pelvic tilt, femoral anteversion, Q-angle, and reduced tibial torsion. Females landed on the ground with significantly increased knee extension and ankle plantarflexion with reduced hip abduction and knee adduction, relatively decreased peak hip adduction, knee internal rotation, and increased knee abduction and ankle eversion. The non-dominant limb showed significantly increased hip flexion, abduction, and external rotation; knee flexion and internal rotation; and ankle inversion at initial contact. Further, the non-dominant limb showed increased peak hip and knee flexion, relatively reduced peak hip adduction, and increased knee abduction and internal rotation. It could be suggested that LEAs and LEKs observed in females and non-dominant limbs might contribute to a greater risk of anterior cruciate ligament injuries.

Prevalence of joint hypermobility in children and adolescents: A systematic review and meta-analysis

Background:

The inconsistent results of different studies regarding the prevalence of joint hypermobility (JH) or joint laxity in children and adolescents made us conduct a meta-analysis on the prevalence of JH in this age group.

Materials and Methods:

We searched electronic databases including Trip, Scopus, Medline, Embase, PubMed, and Google Scholar; some Iranian databases including Iran Medex and Magiran; and Scientific Information Database to find studies in which the prevalence of JH in children and adolescents had been reported since January 1990 to April 2017. In this process, two researchers evaluated the articles separately while they were not aware of each other's method, and they extracted and matched the information.

Results:

Necessary data of twenty studies (15,097 boys and 6048 girls) were entered into this meta-analysis. The age range in these studies was 3–19 years. According to the meta-analysis conducted on the twenty studies, it was determined that the total prevalence of JH among children and adolescents was 34.1% (95% confidence interval [CI]: 33.3%–34.8%). Based on the results obtained from the studies, a significant heterogeneity (I₂ index equals to 99,415 and P ≤ 0.001) was shown, so we used random-effects model; moreover, the overall assessment of studies showed a statistically significant publication bias (P = 0.02). In total, the prevalence in girls was equal to 32.5% (95% CI: 31.4%–33.7%), and in boys, it was equal to 18.1% (95% CI: 17.2%–19.1%).

Conclusion:

According to this meta-analysis, studies showed high heterogeneity, and the prevalence of JH in children and adolescents around the world was equal to 34.1% (95% CI: 33.3%–34.8%) in total, whereas it was higher in girls and lower in older ages.

The significant effect of the medial hamstrings on dynamic knee stability

PURPOSE

While hamstring autograft is a popular option for the general population, BTB autograft is still significantly more popular among professional athletes due to concerns of altering knee kinematics with hamstring harvest. This study seeks to quantify the contribution of the medial hamstrings to knee stability.

METHODS

Valgus knee laxity, anterior tibial translation, and rotational motion were measured in eight fresh-frozen cadaveric knees after forces were applied on the tibia in each plane (coronal, sagittal, and axial). Four muscle loading conditions were tested: (1) physiologic fully loaded pes anserinus, (2) semitendinosus only loaded, (3) gracilis only loaded, and (4) unloaded pes anserinus. The protocol was then repeated with the ACL transected.

RESULTS

In the ACL intact knee, the neutral position of the tibia with an unloaded pes anserinus was significantly more externally rotated (p < 0.01) and anteriorly translated (p < 0.05) at all knee flexion angles than a tibia with a physiologic loaded pes anserinus. Applying an external rotation torque significantly increased external rotation for the fully unloaded (p < 0.001), gracilis only loaded (p < 0.001), and semitendinosus only loaded (p < 0.01) conditions at all flexion angles. Applying a valgus torque resulted in a significant increase in laxity for the fully unloaded condition only at 30° of flexion (p < 0.05). Applying an anterior tibial force resulted in significant increase in anterior translation for the fully unloaded condition at all flexion angles (p < 0.01), and for the gracilis only loaded condition in 30° and 60° of flexion (p < 0.05). Similar results were seen in the ACL deficient model.

CONCLUSION

The medial hamstrings are involved in rotational, translational, and varus/valgus control of the knee. Applying anterior, external rotation, and valgus forces on the hamstring deficient knee significantly increases motion in those planes. Harvesting the gracilis and semitendinosus tendons alters native knee kinematics and stability. This is clinically relevant and should be a consideration when choosing graft source for ACL reconstruction, especially in the elite athlete population.

A threshold value of 3.5 mm of passive anterior tibial subluxation on MRI is highly specific for complete ACL tears

PURPOSE

To identify and quantify passive anterior tibial subluxation on MRI using a standardized measurement protocol and determine the diagnostic threshold of subluxation for complete anterior cruciate ligament tears.

METHODS

A retrospective case-control study was performed. Patients who underwent surgery for a complete isolated ACL tear between 2009 and 2015 were matched for age and gender to controls with an intact ligament on knee MRI. All subjects underwent 1.5 T closed field MR imaging with the same protocol. Measurements were performed on axial sequences to evaluate translation of the medial and lateral condyles compared to the tibial plateau. Each compartment was measured between the vertical tangent to the posterior femoral condyles and the most posterior part of the tibial plateau. The main criterion was global passive subluxation measurements on MRI, corresponding to mean medial and lateral compartment subluxation. The reproducibility and diagnostic value of passive subluxation were calculated.

RESULTS

Sixty (30/30) subjects were included, mean age 27.1 ± 1.7 years, 20 women and 40 men. Patients had a significantly higher global passive subluxation than controls (3.3 ± 0.6 mm vs 0.6 ± 0.2 mm, respectively p < 0.00001). Reproducibility was excellent and the diagnostic value of passive subluxation for a complete ACL tear was fair. A passive subluxation threshold of 3.5 mm had a sensitivity of 55.2%, a specificity of 100% and 77.6% of well-classified subjects.

CONCLUSION

The calculated cutoff value for global passive subluxation to identify patients with a complete ACL tear was 3.5 mm, with excellent specificity and a high positive likelihood ratio. Suboptimal clinical results following ACL reconstruction could be partially due to failure to restore an anatomical femorotibial relationship.

LEVEL OF EVIDENCE

III.

Physiologic Preoperative Knee Hyperextension Is a Predictor of Failure in an Anterior Cruciate Ligament Revision Cohort: A Report From the MARS Group

BACKGROUND

The occurrence of physiologic knee hyperextension (HE) in the revision anterior cruciate ligament reconstruction (ACLR) population and its effect on outcomes have yet to be reported. Hypothesis/Purpose: The prevalence of knee HE in revision ACLR and its effect on 2-year outcome were studied with the hypothesis that preoperative physiologic knee HE ≥5° is a risk factor for anterior cruciate ligament (ACL) graft rupture.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients undergoing revision ACLR were identified and prospectively enrolled between 2006 and 2011. Study inclusion criteria were patients undergoing single-bundle graft reconstructions. Patients were followed up at 2 years and asked to complete an identical set of outcome instruments (International Knee Documentation Committee, Knee injury and Osteoarthritis Outcome Score, WOMAC, and Marx Activity Rating Scale) as well as provide information regarding revision ACL graft failure. A regression model with graft failure as the dependent variable included age, sex, graft type at the time of the revision ACL surgery, and physiologic preoperative passive HE ≥5° (yes/no) to assess these as potential risk factors for clinical outcomes 2 years after revision ACLR.

RESULTS

Analyses included 1145 patients, for whom 2-year follow-up was attained for 91%. The median age was 26 years, with age being a continuous variable. Those below the median were grouped as "younger" and those above as "older" (age: interquartile range = 20, 35 years), and 42% of patients were female. There were 50% autografts, 48% allografts, and 2% that had a combination of autograft plus allograft. Passive knee HE ≥5° was present in 374 (33%) patients in the revision cohort, with 52% being female. Graft rupture at 2-year follow-up occurred in 34 cases in the entire cohort, of which 12 were in the HE ≥5° group (3.2% failure rate) and 22 in the non-HE group (2.9% failure rate). The median age of patients who failed was 19 years, as opposed to 26 years for those with intact grafts. Three variables in the regression model were significant predictors of graft failure: younger age (odds ratio [OR] = 3.6; 95% CI, 1.6-7.9; P = .002), use of allograft (OR = 3.3; 95% CI, 1.5-7.4; P = .003), and HE ≥5° (OR = 2.12; 95% CI, 1.1-4.7; P = .03).

CONCLUSION

This study revealed that preoperative physiologic passive knee HE ≥5° is present in one-third of patients who undergo revision ACLR. HE ≥5° was an independent significant predictor of graft failure after revision ACLR with a >2-fold OR of subsequent graft rupture in revision ACL surgery. Registration: NCT00625885 ( ClinicalTrials.gov identifier).

A between sex comparison of anterior-posterior knee laxity after anterior cruciate ligament reconstruction with patellar tendon or hamstrings autograft: a systematic review

Anterior-posterior (AP) knee laxity after anterior cruciate ligament (ACL) reconstruction may differ between sexes for different graft types. Females may experience an increase in AP knee laxity following an ACL reconstruction with a hamstrings graft, which is not seen in males with a hamstrings graft or in males or females with a bone-patellar tendon-bone (BTB) graft. The hypothesis of this review is sex differences in AP knee laxity and this will be identified in patients who undergo an ACL reconstruction with a hamstrings graft, while no sex differences will be observed in patients who have an ACL reconstruction with a BTB graft. A systematic search was performed in PubMed, CINAHL and SPORTDiscus. Inclusion criteria were articles published in the English language that studied human subjects who underwent an ACL reconstruction with a BTB or hamstrings autograft, and the presence of a sex comparison on outcome measures including side-to-side difference in AP knee laxity. Methodological quality was assessed using a Modified Coleman Methodology Score. Eleven cohort studies met the inclusion criteria. Six investigated sex differences in both hamstrings and BTB grafts. Three only investigated BTB grafts and two only investigated hamstrings grafts. These studies consistently reported increases in AP knee laxity in females after an ACL reconstruction with a hamstrings graft that was not observed in the other cohorts. This systematic review indicates that female patients have greater AP knee laxity following an ACL reconstruction with a hamstrings autograft compared with males with a similar procedure, and both females and males following an ACL reconstruction with a BTB autograft. These results are derived from lower level evidence, as no randomized control trials have attempted to answer this question. Future studies need to rigorously address this clinical question to confirm the results currently in the literature.

Epidemiology of generalized joint laxity (hypermobility) in fourteen-year-old children from the UK: a population-based evaluation

Objective

Although diagnostic criteria for generalized ligamentous laxity (hypermobility) in children are widely used, their validity may be limited, due to the lack of robust descriptive epidemiologic data on this condition. The present study was undertaken to describe the point prevalence and pattern of hypermobility in 14-year-old children from a population-based cohort.

Methods

We performed a cross-sectional analysis using the Avon Longitudinal Study of Parents and Children, a large population-based birth cohort. Hypermobility among children in the cohort (mean age 13.8 years) was measured using the Beighton scoring system. Objective measures of physical activity were ascertained by accelerometry. Data on other variables, including puberty and socioeconomic status, were collected. Simple prevalence rates were calculated. Chi-square tests and logistic regression analyses were used to assess associations of specific variables with hypermobility.

Results

Among the 6,022 children evaluated, the prevalence of hypermobility (defined as a Beighton score of ≥4 [i.e., ≥4 joints affected]) in girls and boys age 13.8 years was 27.5% and 10.6%, respectively. Forty-five percent of girls and 29% of boys had hypermobile fingers. There was a suggestion of a positive association between hypermobility in girls and variables including physical activity, body mass index, and maternal education. No associations were seen in boys.

Conclusion

We have shown that the prevalence of hypermobility in UK children is high, possibly suggesting that the Beighton score cutoff of ≥4 is too low or that this scoring is not appropriate for use in subjects whose musculoskeletal system is still developing. These results provide a platform to evaluate the relationships between the Beighton criteria and key clinical features (including pain), thereby testing the clinical validity of this scoring system in the pediatric population.

A new diagnostic approach using regional analysis of anterior knee laxity in patients with anterior cruciate ligament deficiency

PURPOSE

The first purpose of this study was to analyze the characteristics of the anterior knee laxity in the three regions of different stiffness in the force-displacement curve, which was obtained from a frequently used arthrometer for quantifying knee joint stability in the patients with anterior cruciate ligament (ACL) rupture and the healthy controls. The second purpose was to compare the characteristics from the regional analysis of the anterior knee laxity between the two subject groups in order to explore proper diagnosis criteria.

METHODS

Seventy-one patients with unilateral ACL tear and eighty healthy controls were enrolled and their anterior knee laxities were tested using the KT-2000 arthrometer. The displacements and stiffness of the three regions were extracted separately and compared between groups to further develop the diagnostic criteria.

RESULTS

The results indicated that the laxity behavior was mostly affected in Region 2 and Region 3 after ACL tear. Two good indicators for ACL tear were found in the receiver operating characteristic (ROC) curve analysis: Region 2 with the displacement larger than 3.7 mm and Region 3 with the stiffness smaller than 22 N/mm. These two criteria provided a better diagnostic accuracy with increased sensitivity.

CONCLUSIONS

The regional analysis method developed in this study could provide more information for understanding the characteristics of the anterior knee laxity and help increase the diagnostic accuracy for ACL rupture.

LEVEL OF EVIDENCE

II.