Increased Lateral Tibial Plateau Slope Predisposes Male College Football Players to Anterior Cruciate Ligament Injury

Modifiers of the Posterior Tibial Slope as a Predisposing Factor for Anterior Cruciate Ligament Ruptures

Background

An increased posterior tibial slope (PTS) has been shown to be a risk factor for anterior cruciate ligament (ACL) ruptures, but the difference in the mean PTS between patients with ACL ruptures and patients with intact ACLs is only approximately 1°, and the PTS has a wide range between 1° and 22°. Therefore, an ACL rupture may be associated with other morphological differences along with the PTS.

Purpose

To evaluate whether the predictive value of the PTS can be increased with new parameters associated with the proximal tibia, distal femur, and extensor mechanism.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

This study included 81 patients who underwent surgical treatment for isolated ACL ruptures and 81 patients with intact ACLs as the control group.Lateral PTS (LPTS), medial PTS (MPTS), lateral femoral condylar offset, anterior patellar offset (APO), lateral tibial plateau offset, and tibial tubercle offset were measured on magnetic resonance imaging. The patella-lateral tibial plateau ratio (P-LTPR) was obtained by dividing the APO by the lateral tibial plateau offset, and the patella-tibial tubercle ratio (P-TTR) was obtained by dividing the APO by the tibial tubercle offset. Patients with ACL ruptures and intact ACLs were subdivided according to an LPTS ≥8° and an LPTS <8° and compared.

Results

The parameters independently associated with ACL ruptures were P-LTPR (P = .001), P-TTR (P = .006), LPTS (P = .016), and MPTS (P = .047). In patients with intact ACLs and an LPTS ≥8°, P-LTPR was negatively correlated with LPTS and MPTS (P = .015 and P < .001, respectively; r = -0.736 and r = -0.758, respectively). In patients with an LPTS ≥8°, P-LTPR was associated with ACL ruptures, with 77.8% sensitivity and 73.7% specificity, at values >1.38, while P-TTR was associated with ACL ruptures, with 68.3% sensitivity and 67.7% specificity, at values >1.77. In patients with an LPTS <8°, P-TTR was associated with ACL ruptures, with 68.7% sensitivity and 77.2% specificity, at values >1.86.

Conclusion

An evaluation of the P-LTPR and P-TTR parameters when assessing anatomic risk factors for an ACL rupture may increase the predictive information provided by the PTS. P-LTPR may be especially useful in re-evaluating the risk of ACL ruptures in patients who are considered to have a high risk because of a high PTS but an intact ACL, and P-TTR may be useful in re-evaluating the risk of ACL ruptures in patients who are considered to have a low risk because of a low PTS.

Increased posterior tibial slope is a risk factor for anterior cruciate ligament injury and graft failure after reconstruction: A systematic review

IMPORTANCE

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) graft failure are important clinical concerns that result in long recovery periods, potential long-term knee instability, and poor patient outcomes. Identifying risk factors such as posterior tibial slope (PTS), meniscal slope (MS), and meniscal bone angle (MBA) is important for improving risk stratification, guiding management decisions, and reducing the incidence of both ACL injury and ACLR graft failure.

OBJECTIVE

This systematic review and meta-analysis aim to determine whether increased PTS, increased MS, and decreased MBA serve as independent predictors of both ACL injury and ACLR graft failure.

EVIDENCE REVIEW

A comprehensive search of the literature was conducted following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. For evaluating ACL injury, the review included comparative studies measuring PTS, MS, or MBA between ACL injury patients and ACL-intact controls. For ACLR graft failure, studies comparing these measurements between patients with ACLR graft failures and those with successful ACLR outcomes were included. Data were pooled using a random-effects model to calculate the overall mean difference (MD) between groups.

FINDINGS

Out of 1,683 initially identified studies, 75 studies were selected for detailed analysis, 53 analyzing ACL injury and 24 studies analyzing ACLR graft failure. The meta-analysis revealed that increased PTS significantly increases the risk of both ACL injury (MD 1.64°; 95% CI: 1.08-2.20, p ​< ​0.01) and ACLR graft failure (MD 1.76°; 95% CI: 1.03-2.48, p ​< ​0.01). This is statistically significant for both lateral and medial PTS, and across both radiograph and magnetic resonance imaging. A higher lateral MS (MD 3.25°; 95% CI: 1.70-4.80, p ​< ​0.01) and a lower lateral MBA (MD -3.85°; 95% CI: -6.38-1.32, p ​< ​0.01) were also significantly associated with an increased risk of ACL injury. However, no statistically significant differences were observed for MS or MBA between ACLR graft failure and successful ACLR groups.

CONCLUSION AND RELEVANCE

The findings indicate that increased PTS, whether measured medially or laterally, is a statistically significant risk factor for both ACL injury and ACLR graft failure. Additionally, increased lateral MS and decreased lateral MBA are associated with ACL injury. This evidence supports the consideration of tibial slope in risk assessment, preoperative planning, and surgical decision-making for both prevention of ACL injury and ACLR procedures. Further research is necessary to fully understand the role of MS and MBA in ACL injury.

LEVEL OF EVIDENCE

Level IV; systematic review of level III-IV studies.

Primary Anterior Cruciate Ligament Injury: Extrinsic and Intrinsic Risk Factors

Anterior cruciate ligament (ACL) injuries continue to increase in incidence despite extensive research into prevention strategies. Many extrinsic and intrinsic risk factors for sustaining ACL injuries have been identified and continue to be investigated. Extrinsic risk factors for ACL injury relate to the athlete's environment, such as the shoe-surface interaction, weather conditions, and sport played. Intrinsic risk factors relate to the athlete's sex, hormones, knee anatomy, landing and pivoting biomechanics, and neuromuscular control. Recent research has highlighted the role of the bony morphology of the proximal tibia and distal femur on primary ACL injury risk, as well as the risk for ACL graft failure. Sex differences in bony and ligamentous morphology of the knee, neuromuscular control, and hormonal factors, such as serum relaxin levels and variations within the menstrual cycle, have been correlated with a higher risk of noncontact primary ACL injuries in female athletes compared with male athletes.

Slope Osteotomies in the Setting of Anterior Cruciate Ligament Deficiency

➤ Posterior tibial slope (PTS) of ≥12° represents an important risk factor for both anterior cruciate ligament (ACL) injury and ACL reconstruction failure.➤ PTS measurements can significantly differ on the basis of the imaging modality and the measurement technique used. PTS should be measured on strictly lateral radiographs, with a recommended proximal tibial length of 15 cm in the image. The PTS measurement can be made by placing 2 circles to define the proximal tibial axis, 1 just below the tibial tubercle and another 10 cm below it. PTS measurements are underestimated when made on magnetic resonance imaging and computed tomography.➤ Slope-reducing osteotomies can be performed using a (1) supratuberosity, (2) tubercle-reflecting transtuberosity, or (3) infratuberosity method. The correction target remains a topic of debate. Although it is controversial, some authors recommend overcorrecting the tibial slope slightly to a range of 4° to 6°. For instance, if the initial slope is 12°, a correction of 6° to 8° should be performed, given the target tibial slope of 4° to 6°.➤ Clinical outcomes following slope-reducing osteotomies have been favorable. However, potential complications, limited data with regard to the impact of slope-reducing osteotomies on osteoarthritis, and uncertainty with regard to the effects on the patellofemoral joint are notable concerns.➤ Patients with complex deformities may need biplanar osteotomies to comprehensively address the condition.

Anterior Cruciate Ligament Injury Prevention and Rehabilitation

At all levels of American football, knee injuries are common, with injuries to the anterior cruciate ligament (ACL) making up a significant proportion. Historically, ACL injuries were career-altering for professional players, but innovative techniques in surgery and rehabilitation have returned many to the field. While there is a consensus on surgical techniques for ACL reconstruction, significant discrepancies remain on injury prevention and rehabilitation programs. This review article describes the burden of ACL injury on players in the National Football League, best practices in injury prevention and rehabilitation, and evidence-based recommendations for preparing injured athletes to return to play.

Posterior Tibial Slope in Patients Undergoing Bilateral Versus Unilateral ACL Reconstruction: MRI and Radiographic Analyses

BACKGROUND

An increased posterior tibial slope (PTS) is a risk factor for primary anterior cruciate ligament (ACL) tears and graft failure, but the PTS has not been well-defined in those who have experienced bilateral ACL injuries.

PURPOSE

The primary aim was to compare the PTS, as well as the rate of an elevated PTS (>12° on lateral radiography; >7° on magnetic resonance imaging [MRI]), between patients who have undergone bilateral ACL reconstruction (ACLR) versus unilateral ACLR. A secondary purpose was to examine whether these associations remained consistent on both plain radiography and MRI.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

We retrospectively identified patients who underwent primary ACLR at our institution from the years 2012 to 2020. Patients who underwent nonsimultaneous bilateral ACLR (n = 53) were matched to those who underwent unilateral ACLR (n = 53) by age, sex, and body mass index. Exclusion criteria were rotated lateral radiographs, MRI scans of inadequate quality, and concomitant ligament injuries or fractures. Those who had undergone unilateral ACLR with <5-year follow-up were further excluded. There were 3 blinded readers who measured the PTS on lateral radiographs, while the medial PTS (MPTS) and lateral PTS (LPTS) were measured on MRI scans. Bivariate regression was performed to determine the correlation between radiographic and MRI measurements.

RESULTS

The PTS on radiography (11.26° vs 10.13°, respectively; P = .044) and the LPTS on MRI (7.32° vs 6.08°, respectively; P = .012) in the bilateral ACLR group were significantly greater than those in the unilateral ACLR group but not the MPTS on MRI (4.55° vs 4.17°, respectively; P = .590). The percentage of patients in the bilateral group with a radiographic PTS >12° was 41.0% compared with 13.2% in the unilateral group (P = .012). The bilateral group had a significantly higher rate of an LPTS >7° compared with the unilateral group (53.8% vs 32.1%, respectively; P = .016) but not for an MPTS >7° (P = .190). On MRI, the LPTS (6.90°± 2.73°) was significantly greater than the MPTS (4.41°± 2.92°) (P < .001). There was a weak correlation between MPTS and radiographic PTS measurements (R = 0.24; P = .021), but LPTS and radiographic PTS measurements were not significantly correlated (R = 0.03; P = .810).

CONCLUSION

Patients who underwent bilateral ACLR had a significantly greater PTS on radiography and a significantly greater LPTS on MRI compared with those who underwent unilateral ACLR. The rate of a radiographic PTS >12° was 2.4 times greater among patients undergoing bilateral ACLR compared with those undergoing unilateral ACLR. PTS measurements on radiography demonstrated a weak to negligible correlation with PTS measurements on MRI, suggesting that future normative PTS values should be reported specific to the imaging modality.

Editorial Commentary: Bony Morphology Determines the Extent of Concomitant Injuries in Anterior Cruciate Ligament Injured Knees

The bony morphology of both tibia and femur has been found to influence the risk of anterior cruciate ligament (ACL) injuries. Quantifying the femoral condylar's sagittal morphology, the lateral femoral condyle ratio (LFCR) has been associated with injuries to the anterolateral knee joint capsule, including the anterolateral ligament in ACL-injured knees. Rotational instability may be in part attributable to femoral anisometry with an increase of the LFCR contributing to increased laxity and risk for ACL ruptures as well as concomitant injuries. While there is currently no surgical treatment available to change the bony morphology of the femur, possibilities such as the addition of a lateral extra-articular tenodesis, adjustment of graft selection, or modification of surgical techniques may mitigate the risk of ACL rerupture in patients with a high LFCR.

Determining the relationship between tibiofemoral geometry and passive motion with partial least squares regression

Tibiofemoral geometry influences knee passive motion and understanding their relationship can provide insight into knee function and mechanisms of injury. However, the complexity of the geometric constraints has made characterizing the relationship challenging. The aim of this study was to determine the tibiofemoral bone geometries that explain the variation in passive motion using a partial least squares regression (PLSR) model. The PLSR model was developed for 29 healthy cadaver specimens (10 female, 19 male) with femur and tibia geometries retrieved from MRI images and six degree-of-freedom tibiofemoral kinematics determined during a flexion cycle with minimal medial pressure. The first 13 partial least squares (PLS) components explained 90% of the variation in the kinematics and accounted for 89% of the variation in geometry. The first three PLS components which shared geometric changes to particular surface congruencies of the tibial and femoral condyles explained the most amount of variation in the kinematics, primarily in anterior-posterior translation. Meanwhile, variations in femoral condyle width and the intercondylar space, tibia plateau size and conformity, and tibia eminences heights in PLS 2 and 4 explained the greatest amount of variation in internal-external rotation. PLS 4 exhibiting variation in overall size of the knee accounted for greatest amount of variation in geometry (50%) and had the greatest influence on the abduction-adduction motion and some on internal-external rotation but, overall, explained only a small proportion of the kinematics (10%). Elucidating the complex relationship between tibiofemoral bone geometry and passive kinematics may help personalize treatments for improved functional outcomes in patients.

Loading mechanisms of the anterior cruciate ligament

This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

The posterior tibial slope and Insall-Salvati index in operative and nonoperative adolescent athletes with Osgood-Schlatter disease

INTRODUCTION

Osgood-Schlatter disease (OSD) is a common cause of anterior knee pain in adolescent athletes due to repetitive stress on the tibial tubercle. The posterior tibial slope angle (PTSA) and the Insall-Salvati Index (ISI) play a role in knee biomechanics. However, to our knowledge, the posterior tibial slope and patellar height have not been compared in operated versus nonoperative OSD patients. The purpose of the current study is to compare the differences in the PTSA and the ISI between operative and nonoperative patients with OSD.

MATERIALS AND METHODS

The study was approved by the College of Medicine's Institutional Review Board. A retrospective review was performed on 75 adolescent athletes with OSD between 2008 and 2019. The data extracted included: age, sex, body mass index (BMI), sporting activity and type, mechanism of injury (MOI), chronicity of symptoms, PTSA, and the ISI. Descriptive and quantitative statistics were used.

RESULTS

Seventy-five patients (88 knees) with OSD were studied (28 boys, 47 girls). The average age was 12.2 years and the average BMI was 22.3. The mechanism of injury (MOI) included repetitive stress (77%) and trauma (23%). The duration of knee pain averaged 10.3 months. Sixty-six patients were included in the nonoperative cohort. Nine patients were included in the operative cohort and underwent surgery due to persistent symptoms after skeletal maturity with tubercleplasty and/or ossicle excision. The average PTSA was 12.1° ± 1.7° and average ISI was 1.05 ± 0.15. Comparing the operative and nonoperative patients, we found no significant difference in PTSA (11.2° ± 0.73° versus 12.8° ± 1.8°, p < 0.064). However, we did find that patients treated operatively had a lower ISI (0.95 ± 0.18 versus 1.14 ± 0.13, p < 0.001).

CONCLUSION

In patients with OSD, operative and nonoperative patients demonstrated a similar PTSA. On the other hand, the ISI was higher in nonoperative patients. In the current paper, a decreased ISI was helpful in predicting the need for operative intervention in symptomatic patients after skeletal maturity.

STRENGTH MAINTENANCE TRAINING IN THE REHABILITATION OF COMMON INJURIES IN SOCCER ATHLETES DURING THE WINTER

ABSTRACT Introduction: The level of soccer athletics develops rapidly, requiring athletes to be more capable of training, strengthening, and competitive readiness. Often, these characteristics are compromised by preventable injuries resulting from excessive or unreasonable training, especially in winter. The outcome is the athlete’s absence from games during the season, compromising the team’s qualification. Objective: Improve the treatment and prevention of the major injuries caused to soccer athletes in winter. Methodology: The main injuries resulting from poor training and the best practices of awareness and recovery were researched. The selected actions were implemented on ten athletes with follow-up during the entire annual season, totaling 50 games. Results: An increase in the number of active athletes during the competition phase was observed in 7 games, and competition efficiency was increased by 14%. Conclusion: Soccer players can get better rehabilitation through practical strength maintenance training in the rehabilitation phase between winter training and competitions. This scientific and rational method has a significantly positive effect on the physical performance of athletes. Evidence Level II; Therapeutic Studies – Investigating the results.

Meniscal Bone Angle Is a Strong Predictor of Anterior Cruciate Ligament Injury

Purpose

To evaluate the influence of lateral posterior tibial slope (LPTS) and meniscal bone angle (MBA) on primary anterior cruciate ligament (ACL) tear risk in an adult population through the LPTS-MBA ratio.

Methods

A retrospective case-control study was performed with patients from a tertiary hospital who underwent primary ACL surgery and had preoperative magnetic resonance imaging (MRI). These subjects were matched by age and sex in a 1:1 ratio to patients who had an MRI without ACL tear. LPTS and MBA were measured on MRI scan. Quantitative data are presented in the median ± interquartile range (IQR). Identification of independent risk factors for primary ACL tear was performed using multivariable logistic regression. Receiver operating characteristics curves detected any variable with strong discriminative capacity.

Results

In total, 95 patients with primary ACL tear confirmed on MRI were matched with 95 controls (N = 190). Nearly 80% were male subjects, with a median age of 26 years. In the ACL tear group, the median value of LPTS-MBA ratio was 0.20 (IQR 0.11-0.37) versus 0.12 (IQR 0.08-0.19) in the control group (P = .001). LPTS had a median value of 4.20° in the ACL tear group (IQR 2.05-7.35°) and 2.90° in the control group (IQR, 2.05-5.00°) (P = .026), whereas MBA was 19° (IQR, 16-24°) versus 26° (IQR, 24-30°) (P = .001), respectively. Logistic regression showed that LPTS (odds ratio 1.20, 95% confidence interval 1.03-1.42, P = .021) and MBA (odds ratio 0.78, 95% confidence interval 0.71-0.85, P = .001) were independent predictors. The area under the curve (AUC) of LPTS-MBA ratio was 0.69, greater than that of LPTS alone (AUC = 0.61) but lower than that for MBA (AUC = 0.82).

Conclusions

In this study, a reduced MBA was the strongest predictive variable associated with a primary ACL tear. A threshold of 22.35° of MBA was associated with an increased risk of ACL tear, with a sensitivity of 70% and specificity of 84%. A cut-off of 0.22 of LPTS-MBA was associated with an increased risk of ACL tear, with a sensitivity of 55% and specificity of 87%.

Level of Evidence

Level III, case-control study.

Narrow Notch Width and Low Anterior Cruciate Ligament Volume Are Risk Factors for Anterior Cruciate Ligament Injury: A Magnetic Resonance Imaging-Based Study

BACKGROUND

The relationship between anterior cruciate ligament (ACL) injury and anatomical structures is still a topic of debate.

PURPOSE

The aim of this study was to compare knee geometry in demographically matched ACL-injured and ACL-intact athletes.

METHODS

We conducted a case-control study comparing 2 groups, each consisting of 55 professional athletes (44 men and 11 women): 1 group with complete ACL tears (cases) and 1 group with intact ACLs (controls). The groups were compared using magnetic resonance imaging (MRI) in terms of intercondylar notch geometry, tibial plateau characteristics, and ACL volume.

RESULTS

Among cases and controls, we found the cases had lower notch width (20.24 ± 2.68 mm vs. 22.04 ± 2.56 mm, respectively) and notch width index (0.29 ± 0.03 vs. 0.31 ± 0.03, respectively). The mean ACL volume in the cases (1181.63 mm³ ± 326 mm³) was also lower than in controls (1352.61 mm³ ± 279.84 mm³). The parameters of tibial slope geometry were comparable between groups. In addition, women had lower ACL volume than men (1254 ± 310 mm³ vs. 890 ± 267 mm³, respectively) and higher medial posterior tibial slope (4.76 ± 2.6 vs. 6.63 ± 1.83, respectively). Among cases, women had narrower notch width than men (16.9 ± 2.42 mm vs. 21.08 ± 2.03 mm). However, notch width index was comparable between male (0.3 ± 0.02) and female (0.28 ± 0.03) cases.

CONCLUSION

Our findings suggest that narrow notch width and low ACL volume may enhance the risk of ACL injury among athletes. There was no association found between posterior tibial slope and ACL injury between athletes with injured ACLs and controls. Further study is indicated.

Can MRI knee joint measurements predict the population at risk of ACL injury?

BACKGROUND

Anterior cruciate ligament (ACL) injuries have been increasing significantly over time. The relationship between the ACL injury and the knee joint structures is poorly understood. The purpose of this study is to examine whether the measurements of different structures in the knee joint are linked with ACL injury in affected patients.

METHODS

This retrospective case-control study included patients who suffered from ACL tears and underwent magnetic resonance imaging (MRI). A control group of patients with no knee pathologies on MRI was included. Fourteen knee variables, including lateral meniscus (LM) posterior horn height, length, depth, and volume; medial meniscus (MM) posterior horn height, length, depth, and volume; lateral and medial (MFC) femoral condyle sphere diameter; lateral and medial tibial plateau length; and patella tendon horizontal and vertical diameter, were collected. A multivariate logistic regression including LM posterior horn depth, MM posterior horn length, MM volume, MFC sphere diameter, and patella tendon horizontal diameter and receiver operating characteristic curve, was used to compare the two groups.

RESULTS

A total of 85 patients were included in our study; 54 suffered from ACL injuries and 31 as a control group with normal knee MRI. Logistic regression revealed that increased LM posterior horn depth (OR = 1.27; 95% CI = 1.03-1.56; p = 0.028), decreased MM posterior horn length (OR = 0.71; 95% CI = 0.55-0.93; p = 0.013), and MFC sphere diameter (OR = 1.20; 95% CI = 1.01-1.43; p = 0.035) were independent risk factors for ACL rupture. The MFC sphere diameter yielded the highest area under the curve: 0.747 (95% CI, 0.632-0.862). No difference was found in the other measurements between the two groups.

CONCLUSIONS

Concerning the difference in anatomical variations, the lateral meniscus posterior horn depth and medial femoral condyle sphere diameter were higher, while medial meniscus posterior horn length was lower in patients with an ACL injury. These structural knee measurements could have a possible increase in the likelihood of sustaining an ACL injury and can be used by clinicians to predict ACL injury.

Posterior Tibial Slope in Patients With Torn ACL Reconstruction Grafts Compared With Primary Tear or Native ACL: A Systematic Review and Meta-analysis

Background:

Increased posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) rupture and failure of ACL reconstruction (ACLR) grafts.

Purpose:

The purpose was to conduct a systematic review of literature on PTS measurements and to conduct a meta-analysis of comparable PTS measurements based on a patient’s ACL status. It was hypothesized that patients with torn ACLR grafts would have significantly larger medial and lateral PTS compared with patients with native ACLs or those who underwent primary ACLR.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic review was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included were studies that reported medial and/or lateral PTS measurements, those that reported PTS measurements based on ACL status (ie, intact ACL, primary ACL tear, failed ipsilateral ACLR, or revision ACLR), and those that reported their specific PTS measurement technique. Average PTS measurements, measurement location (medial or lateral tibial plateau) and technique, imaging modality used, and ACL status were extracted from each study. Data were pooled using DerSimonian and Laird random-effects models, and results were compared using the Altman interaction test.

Results:

The literature search identified 1705 studies, of which 82 (N = 12,971 patients) were included. There were 4028 patients in the intact ACL group (31%), 7405 in the primary ACLR group (57%), and 1538 in the failed ACLR group (12%). Measurements were obtained from lateral radiographs in 31 studies (38%), from magnetic resonance imaging in 47 studies (57%), and from computed tomography in 4 studies (5%). The failed ACLR group had a significantly larger lateral PTS (9.55°; 95% CI, 8.47°-10.63°) than either the primary ACL tear (7.13°; 95% CI, 6.58°-7.67°) or intact ACL (5.57°; 95% CI, 5.03°-6.11°) groups (P < .001 for both). The failed ACLR group also had a significantly larger medial PTS (9.05°; 95% CI, 7.80°-10.30°) than the primary (6.24°; 95% CI, 5.71°-6.78°) or intact ACL (6.28°; 95% CI, 5.21°-7.35°) groups (P < .001 for both).

Conclusion:

Both lateral and medial PTS measurements were greater in patients who had failed previous ACLR than those with a primary ACL tear or an intact native ACL. The lateral PTS of patients with primary ACL tears was greater than those with an intact native ACL.

Screening Tests for Assessing Athletes at Risk of ACL Injury or Reinjury-A Scoping Review

Various tests are available to assess athletes for factors associated with their susceptibility and risk of anterior cruciate ligament (ACL) injury or reinjury; however, it is unclear which tests are clinically meaningful and what should be considered when using them. Therefore, the aim of this scoping review was to screen and summarize testing and to derive evidence-based recommendations for clinicians, practitioners and future research. Five databases were searched to identify studies addressing musculoskeletal morphology or functional-performance-related screening tests with a clear conceptual link or an evidence-based relationship to ACL (re)injury. A quality rating was carried out using the National Institutes of Health (NIH) Study-Quality Assessment Tool. Six different categories of common screening tests were identified: balance and postural control, gait- and running-related tests, joint laxity, joint morphology and anthropometrics, jump tests and strength tests. Predicting future injury in a complex, dynamic system based on a single screening test is methodologically challenging, which is also reflected in the highly controversial findings in the literature regarding potential associations between specific screening tests and the occurrence of ACL injuries and reinjuries. Nonetheless, various screening tests can provide clinically relevant information on ACL-(re)injury-related factors and help to provide tailored preventive measures. A selection of corresponding evidence-based recommendations is derived and presented in this scoping review.

Lateral posterior tibial slope and length of the tendon within the tibial tunnel are independent factors to predict tibial tunnel widening following anatomic anterior cruciate ligament reconstruction

PURPOSE

This study aimed to conduct a multivariate analysis to identify independent factors that predict tibial tunnel widening (TW) after anatomical anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) grafts.

METHODS

In total, 103 patients who underwent ACL reconstructions using BPTB grafts were included. Tunnel aperture area was measured using three-dimensional computed tomography 1 week and 1 year postoperatively, and the tibial TW was calculated. The patients were divided into group S comprising 58 patients who had tibial TW < 30% and group L comprising 45 patients who had tibial TW > 30%, retrospectively. Using univariate analyses, age, gender, body mass index, Tegner activity scale, the time between injury and surgery, tibial tunnel location, tibial tunnel angle, medial posterior tibial slope, lateral posterior tibial slope, and length of the tendon in the tibial tunnel were compared between two groups. Multivariate regression analysis was conducted to reveal the independent risk factors for the tibial TW among preoperative demographic factors and radiographic parameters that correlated with the tibial TW in the univariate analyses.

RESULTS

Compared with those at 1 week postoperatively, mean tibial tunnel aperture areas were increased by 30.3% ± 26.8% when measured at 1 year postoperatively. The lateral posterior tibial slope was significantly larger (p < 0.001), and the length of the tendon within the tibial tunnel was significantly longer in group L than that in group S (p = 0.03) in the univariate analyses. Multivariate regression analysis showed that the increase in lateral posterior tibial slope (p = 0.001) and the length of the tendon within the tibial tunnel (p = 0.03) were predictors of the tibial TW.

CONCLUSIONS

This study showed that increased lateral posterior tibial slope and a longer tendinous portion within the tibial tunnel were independent factors that predicted the tibial TW following anatomical ACL reconstruction with a BPTB graft.

LEVEL OF EVIDENCE

III.

Relationship between anterior cruciate ligament rupture and the posterior tibial and meniscal slopes in professional soccer athletes

OBJECTIVE

Several anatomical parameters have been associated with increased risk of anterior cruciate ligament rupture; however, published studies provide conflicting results. The objectives of this study are to assess whether there is a relationship between anterior cruciate ligament rupture and the lateral and medial posterior tibial slopes, as well as the lateral and medial posterior meniscal slopes and posterior tibial and meniscal delta-slopes.

MATERIALS AND METHODS

A retrospective case-control study was conducted in professional soccer athletes, using images from knee magnetic resonance imaging scans in athletes with clinical and radiological diagnosis of anterior cruciate ligament rupture, and control group, with no signs of ligament rupture.

RESULTS

The lateral and medial posterior tibial slopes, the lateral and medial posterior meniscal slopes, and the posterior tibial and meniscal delta-slopes showed significant differences between the groups (p < 0.05). Multivariate analysis logistic regression revealed that the lateral and medial posterior meniscal slopes proved to be predictors for increased risk of anterior cruciate ligament rupture in professional soccer players.

CONCLUSION

Posterior tibial and meniscal slopes and tibial and meniscal delta-slopes are related to a greater risk of rupture of the anterior cruciate ligament in professional male soccer athletes. The lateral and medial posterior meniscal slopes are predictors for ligament rupture.

A Surgical Algorithm According to Pivot-Shift Grade in Patients With ACL Injury: A Prospective Clinical and Radiological Evaluation

Background:

Some patients have a positive pivot-shift finding and rotational instability after anterior cruciate ligament (ACL) reconstruction (ACLR). Three major pathologies known to affect the pivot-shift examination include ACL tear, anterolateral ligament injury, and loss of posterior lateral meniscus root function.

Purpose:

To describe a surgical algorithm determining indications for lateral extra-articular tenodesis (LET) based on intraoperative pivot-shift examination to prevent postoperative pivot shift and rotational instability and to evaluate the 2-year clinical and functional outcomes.

Study Design:

Case series; Level of evidence, 4.

Methods:

The study included 47 consecutive patients (39 men and 8 women) who underwent operative treatment for ACL injury between 2016 and 2017. Pivot-shift examination was performed under anesthesia, and the pivot shift was graded as grade 1 (glide), grade 2 (clunk), or grade 3 (gross). According to the surgical algorithm, single-bundle ACLR was performed in patients with grade 1 pivot shift. In patients with grade 2 with loss of posterior lateral meniscus root function, concurrent lateral meniscal repair was performed, and in patients with grade 2 with an intact lateral meniscus posterior root, concurrent extra-articular iliotibial band tenodesis was performed. Patients with grade 3 underwent ACLR, lateral meniscal repair, and LET. Clinical and radiographic evaluations were performed.

Results:

The mean age was 27.2 years (range, 16-56 years). In total, 26 (55.3%) patients were evaluated as having pivot-shift grade 1; 16 (34%) patients, grade 2; and 5 (10.6%) patients, grade 3. A total of 7 (14.9%) patients underwent LET in addition to ACLR. Two of these patients had pivot-shift grade 2, and LET was performed since the lateral meniscus posterior root was intact. In 14 of 16 patients with grade 2, lateral meniscus root disruption was detected, and lateral meniscal repair was performed. One patient was excluded from the further follow-up because of graft failure. At a mean postoperative follow-up of 29 months in 46 patients, the pivot-shift examination was negative in all patients. The mean Lysholm and International Knee Documentation Committee subjective scores were 95.35 ± 4.40 and 82.87 ± 9.36, respectively. Radiographic evidence of osteoarthritis was not detected.

Conclusion:

Only 14.9% of patients needed LET. With proper ACL, lateral meniscal, and anterolateral ligament surgery, it was possible to prevent positive pivot-shift findings postoperatively.

Tibial Slope Can Be Maintained During Medial Opening-Wedge Proximal Tibial Osteotomy With Sagittally Oriented Hinge, Posterior Plate Position, and Knee Hyperextension: A Cadaveric Study

PURPOSE

The purpose of this study is (1) to determine if, when optimizing modern techniques, medial opening-wedge osteotomies can effectively maintain tibial slope and (2) to determine how different magnitude coronal plane corrections affect tibial slope.

METHODS

Proximal tibial osteotomies (PTOs) were performed on 10 fresh-frozen cadaveric knees leaving a consistent lateral hinge, using either a 5-mm or a 10-mm trapezoidal wedged osteotomy plate. Techniques including posterior plate placement; a trapezoidal, sloped plate; and knee hyperextension were used during plate fixation to help close the anterior osteotomy gap. Medial coronal proximal tibia angle and posterior tibial slope were measured preosteotomy, after a 5-mm implant, and after a 10-mm implant using true anteroposterior and lateral fluoroscopic images. Three independent observers performed all radiographic measurements, and intraclass correlation coefficients were calculated.

RESULTS

The 5-mm and 10-mm osteotomy plates increased the coronal medial proximal tibia angle by a mean of 3.4° (range, 3.0°-3.7°) and 7.3° (range, 6.7°-7.7°), respectively. The 5-mm and 10-mm trapezoidal wedged osteotomy plates decreased the posterior tibial slope by a mean of 0.9° (range, 0.5°-1.2°) and 0.3° (range, 0°-0.6°), respectively. Intraobserver reliability was found to be high for both the coronal medial proximal tibia angle (intraclass correlation coefficient [ICC] = 0.897 [0.821-0.946]) and the tibial slope measurements (ICC = 0.761 [0.672-0.826]).

CONCLUSIONS

When optimizing the medial opening-wedge proximal tibial osteotomy, including utilization of a sagittally oriented hinge, placement of a trapezoidal plate posteriorly, and fixation with knee hyperextension, posterior tibial slope can be maintained regardless of the degree of coronal correction.

CLINICAL RELEVANCE

Tibial slope has a significant effect on cruciate ligament stress and a better understanding of coronal plane correction, and its effect on tibial slope is critical when performing proximal tibia osteotomies.

[Influence of lateral posterior tibial slope on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament reconstruction]

Objective

To investigate the influence of lateral posterior tibial slope (LPTS) on tibial tunnel expansion after anatomical single-bundle anterior cruciate ligament (ACL) reconstruction and the effect of tibial tunnel expansion on knee joint function.

Methods

A clinical data of 52 patients with ACL rupture, who underwent arthroscopic anatomical single-bundle reconstruction between November 2018 and December 2019, was retrospectively analyzed. There were 32 males and 20 females with an average age of 34.3 years (range, 14-64 years). There were 22 cases of left knee and 30 cases of right knee. The time from injury to operation ranged from 7 to 30 days, with an average of 15.9 days. The knee function was evaluated by International Knee Documentation Committee (IKDC) score and Lysholm score before operation and at 3 and 6 months after operation. At 3 and 6 months after operation, the LPTS and the width of exit, middle segment, entrance, and 2 cm from the exit of the articular surface of the tibial tunnel were measured based on MRI. The expansion of tibial tunnel was calculated and graded (degrees 0-3). According to LPTS, the patients were divided into group A (<6.0°), group B (6°-12°), and group C (>12°), and the difference in the expansion of tibial tunnel between groups was compared.

Results

All the 52 patients were followed up 6-12 months (mean, 7.1 months). The IKDC and Lysholm scores at 3 and 6 months after operation were significantly different from those before operation ( P<0.05); and the difference of knee scores between 3 and 6 months after operation was significant ( P<0.05). The tibial tunnel expanded after operation, and the relative expansion at the exit and the middle segment showed significant difference between 3 months and 6 months after operation ( P<0.05). The expansion degree of tibial tunnel was rated as degree 0 in 5 cases, degree 1 in 28 cases, degree 2 in 16 cases, and degree 3 in 3 cases at 3 months after operation, and degree 0 in 5 cases, degree 1 in 20 cases, degree 2 in 25 cases, and degree 3 in 2 cases at 6 months after operation. There was no significant difference in IKDC and Lysholm scores between patients with different expansion degrees of tibial tunnels ( P>0.05). The LPTS of 52 patients ranged from -0.8° to 18.7° (mean, 10.6°); there were 7 cases in group A, 24 cases in group B, and 21 cases in group C. There was no significant difference in age, gender, preoperative IKDC and Lysholm scores, and initial width of tibial tunnel between groups ( P>0.05). There was no significant difference in the relative expansion of tibial tunnel at exit and middle segment between groups at 3 months after operation ( P>0.05), and there was significant difference at 6 months after operation ( P<0.05).

Conclusion

After anatomical single-bundle reconstruction of ACL, the tibial tunnel would expand to some extent in a short time. LPTS had a significant effect on tibial tunnel expansion, and the larger the angle was, the more obvious the expansion of the proximal tibial tunnel was. However, early knee function is not affected by tibial tunnel expansion.

Higher risk of contralateral anterior cruciate ligament (ACL) injury within 2 years after ACL reconstruction in under-18-year-old patients with steep tibial plateau slope

PURPOSE

To assess the role of Tibial Plateau Slope (TPS) as risk factor for early Anterior Cruciate Ligament (ACL) reconstruction failure and contralateral ACL injury in a population of patients with less than 18 years of age and operated on with the same surgical technique.

METHODS

Ninety-four consecutive patients (mean age 15.7 ± 1.5 years) with at least 2 years of follow-up, who underwent ACL reconstruction with a single-bundle plus lateral-plasty hamstring technique in the same centre were included. Subsequent ACL injuries (ipsilateral ACL revision or contralateral ACL reconstruction) were assessed within the first 2 years after surgery. Anterior, central, posterior TPS of medial compartment were measured on lateral radiographs and compared between patients with intact graft and those with a second injury. Cut-off values with sensitivity and specificity were calculated with receiver operating characteristic (ROC) analysis. Survival analysis for second ACL injuries and multivariate analysis were performed.

RESULTS

Eight patients (9%) had ipsilateral ACL Revision and eight patients (9%) had contralateral ACL reconstruction. Patients with contralateral injury had a higher Central TPS with respect to those without second injury (12.6° ± 2.8° vs 9.3° ± 3.7°, p = 0.042). No differences were present in patients with ipsilateral ACL revision. Sensitivity and specificity for central TPS slope ≥ 12° to detect a contralateral rupture were 63% and 75% (p = 0.0092), for Anterior TPS were 100% and 52% (p = 0.0009). Patients with TPS values exceeding these cut-offs had higher rate of contralateral ACL injuries (19%vs4%, p = 0.0420) and lower 2-year survival (p = 0.0049). Multivariate analysis identified pre-operative sport level and TPS (either anterior or central) as risk factors for contralateral injuries.

CONCLUSIONS

Steep tibial plateau slope ≥ 12° is associated with a higher risk of contralateral ACL injury within 2 years after ACL reconstruction in patients less than 18 years of age. However, TPS has no role in early ipsilateral re-injury after combined ACL reconstruction and lateral plasty. The clinical relevance is that both the surgeon and the patient should be aware of this higher risk and consider it in the rehabilitation phase to reduce the incidence of such injuries.

LEVEL OF EVIDENCE

III.

Predictors of Pediatric Anterior Cruciate Ligament Injury: The Influence of Steep Lateral Posterior Tibial Slope and Its Relationship to the Lateral Meniscus

PURPOSE

To examine the relationship between posterior tibial slope and lateral meniscal bone angle (LMBA) on anterior cruciate ligament (ACL) tear risk in a pediatric population.

METHODS

In this case-control study, non-contact ACL-injured pediatric patients with no significant lateral meniscal lesions were matched by age and sex in a 1:1 ratio to a group of radiologically normal controls. Knee magnetic resonance imaging (MRI) studies were analyzed by 3 independent, blinded observers measuring the medial posterior tibial slope (MTS), lateral posterior tibial slope (LTS), and LMBA. Sagittal slope asymmetry was calculated as the absolute difference in degrees between slopes, and the relationship between LMBA and LTS was calculated as a ratio. Binary logistic regressions identified independent predictors of ACL injury. Receiver operator characteristics were performed to determine predictive accuracy.

RESULTS

20 study patients were compared with 20 sex- and age-matched controls (age 14.8 ± 2.42, mean ± standard deviation). LTS was significantly higher in the ACL-injured group (11.30° ± 3.52° versus 7.00° ± 2.63°, P = .0001), as were the absolute slope difference (7.10 ± 2.92° versus 3.14 ± 3.25°, P = .0002) and LTS:LMBA ratio (0.46 ± 0.17 versus 0.26 ± 0.12, P = .0001). No significant differences were observed for MTS or LMBA. Independent predictors were LTS (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.18 to 2.13, P = .002), LTS:LMBA ratio (OR 3.13, 95% CI 1.48 to 6.62, P = .003), and absolute slope difference (OR 1.65, 95% CI 1.17 to 2.32, P = .005). LTS:LMBA ratio was the strongest predictor variable (area under the curve 0.86).

CONCLUSION

This study suggests that LTS, absolute slope difference, and LTS:LMBA ratio are significant pediatric ACL-injury risk factors. All 3 demonstrate good predictive accuracy; however, the relationship between steep LTS and shallow LMBA was the strongest predictor.

LEVEL OF EVIDENCE

III, case-control study.

Notch Volume Measured on Magnetic Resonance Imaging Is Better Than 2-Dimensional Notch Parameters for Predicting Noncontact Anterior Cruciate Ligament Injury in Males

PURPOSE

To evaluate and compare intercondylar notch volume with other 2-dimensional notch parameters (measured on magnetic resonance imaging [MRI]) for prediction of noncontact anterior cruciate ligament (ACL) injury in males.

METHODS

Retrospective case-control study in males based on MRI images. The case group consisted of 80 noncontact ACL-injured males and a control group of 80 age- and height-matched ACL-intact males. Inclusion criteria were 18 to 50 years old, full-thickness tear, MRI obtained within 1 year of injury, and ACL tear visually documented during arthroscopy. Multiligamentous, bilateral, or concomitant bony injuries were excluded. Notch volume and 2D parameters in both planes, including notch depth, notch width, intercondylar notch angle, notch-width index, and notch-shape index, were measured on MRI and compared. Slice interval was included in the formula for notch-volume assessment. Bivariate Pearson correlation between notch volume and 2D parameters was estimated. Multivariate conditional logistic regression analysis was used for predictor model. Receiver operating characteristic (ROC) curves were plotted.

RESULTS

All MRIs had a standard slice thickness of 3 mm and slice interval of 0.3 mm. Notch volume (P < .001), notch angle in the axial plane (P = .001), and notch width in the coronal plane (P = .009) were significantly smaller in the ACL-injured group. Notch volume had inconsistent and negligible to low correlation with 2D parameters. Notch volume was the only significant contributor in the predictor model (P < .001). ROC curve showed that notch volume had highest area under the curve of 84.1% and optimal cutoff at 7.1550 cm³ (specificity, 88.7%; sensitivity, 65%).

CONCLUSION

Significantly smaller intercondylar notch volume is associated with noncontact ACL injury in men and is the most important predictor for such an injury (optimal cutoff of 7.1550 cm³). Two-dimensional notch parameters are inconsistently associated with noncontact ACL injury in men, and none of the 2D parameters can be used as a surrogate for notch volume. Two-dimensional notch parameters fare poorly in predicting noncontact ACL injury in males. Notch volume measurement should include slice interval as a factor.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Is There a Role of Meniscal Morphology in the Risk of Noncontact Anterior Cruciate Ligament Rupture? A Case-Control Study

The purpose of this study was to identify the anatomical risk factors and determine the role of meniscal morphology in noncontact anterior cruciate ligament (ACL) rupture. A total of 126 patients (63 with noncontact ACL rupture and 63 age- and sex-matched controls) with intact menisci were included in this retrospective case-control study. On knee magnetic resonance imaging (MRI), meniscal morphometry (anterior, corpus, and posterior heights and widths of each meniscus), tibial slope (medial and lateral separately), notch width index, roof inclination angle, anteromedial bony ridge, tibial eminence area, and Q-angle measurements were assessed. The data were analyzed using multiple regression analyses to identify independent risk factors associated with ACL rupture. Using a univariate analysis, medial and lateral menisci anterior horn heights (p < 0.001; p < 0.003), medial and lateral menisci posterior horn heights (p < 0.001; p < 0.001), lateral meniscus corpus width (p < 0.004), and notch width index (p < 0.001) were significantly higher in the control group. Lateral tibial slope (p < 0.001) and anteromedial bony ridge thickness (p < 0.001) were significantly higher in the ACL rupture group. Multivariate analysis revealed that decreased medial meniscus posterior horn height (odds ratio [OR]: 0.242; p < 0.001), increased lateral meniscus corpus width (OR: 2.118; p < 0.002), increased lateral tibial slope (OR: 1.95; p < 0.001), and decreased notch width index (OR: 0.071; p = 0.046) were independent risk factors for ACL rupture. Notch stenosis, increased lateral tibial slope, decreased medial meniscus posterior horn height, and increased lateral meniscus corpus width are independent anatomical risk factors for ACL rupture. Meniscal morphological variations also play a role in ACL injury. This is a Level III, retrospective case-control study.

Narrow Notch Width is a Risk Factor for Anterior Cruciate Ligament Injury in the Pediatric Population: A Multicenter Study

Purpose

The purposes of this study were to evaluate the notch width index (NWI) as a risk factor for anterior cruciate ligament (ACL) rupture in the pediatric and adolescent patient population via multicenter analysis and to detect any differences in the NWI among cohorts having sustained either a unilateral or bilateral ACL rupture.

Methods

A consecutive series of patients ≤19 years old was enrolled from January 1999 through July 2010 at 2 academic pediatric orthopaedic tertiary-care hospitals. Demographic and anatomic morphology data were collected for 3 cohorts: unilateral ACL ruptures, bilateral ACL ruptures, and a control group. A single blinded reviewer determined notch width measurements via T2 coronal magnetic resonance imaging sequences in a standardized manner, using a previously described technique.

Results

Of the 68 patients included for analysis, 22 sustained unilateral ACL rupture, 23 sustained bilateral ruptures, and 23 comprised the control group. There was a statistically significant difference appreciated in direct comparison of the NWI in the bilateral rupture group and the control group, as well as between the unilateral rupture group and the control group. There was no statistically significant difference between the NWI in the unilateral versus the bilateral rupture group.

Conclusion

Given the known inconsistencies in the existing literature, our findings provide further support of a narrow NWI as a significant contributing factor to both unilateral and bilateral ACL injury risk in the pediatric and adolescent patient population.

Level of Evidence

III, retrospective cohort study.

Beighton Score, Tibial Slope, Tibial Subluxation, Quadriceps Circumference Difference, and Family History Are Risk Factors for Anterior Cruciate Ligament Graft Failure: A Retrospective Comparison of Primary and Revision Anterior Cruciate Ligament Reconstructions

PURPOSE

To assess patient history, physical examination findings, magnetic resonance imaging (MRI) and 3-dimensional computed tomographic (3D CT) measurements of those with anterior cruciate ligament (ACL) graft failure compared with primary ACL tear patients to better discern risk factors for ACL graft failure.

METHODS

We performed a retrospective review comparing patients who underwent revision ACL reconstruction (ACLR) with a primary ACLR group with minimum 1-year follow-up. Preoperative history, examination, and imaging data were collected and compared. Measurements were made on MRI, plain radiographs, and 3D CT. Inclusion criteria were patients who underwent primary ACLR by a single surgeon at a single center with minimum 1-year follow-up or ACL graft failure with revision ACLR performed by the same surgeon.

RESULTS

A total of 109 primary ACLR patients, mean age 33.7 years (range 15 to 71), enrolled between July 2016 and July 2018 and 90 revision ACLR patients, mean age 32.9 years (range 16 to 65), were included. The revision ACLR group had increased Beighton score (4 versus 0; P < .001) and greater side-to-side differences in quadricep circumference (2 versus 0 cm; P < .001) compared with the primary ACLR group. A family history of ACL tear was significantly more likely in the revision group (47.8% versus 16.5%; P < .001). The revision group exhibited significantly increased lateral posterior tibial slope (7.9° versus 6.2°), anterolateral tibial subluxation (7.1 versus 4.9 mm), and anteromedial tibia subluxation (2.7 versus 0.5 mm; all P < .005). In the revision group, femoral tunnel malposition occurred in 66.7% in the deep-shallow position and 33.3% in the high-low position. The rate of tibial tunnel malposition was 9.7% from medial to lateral and 54.2% from anterior to posterior. Fifty-six patients (77.8%) had tunnel malposition in ≥2 positions. Allograft tissue was used for the index ACLR in 28% in the revision group compared with 14.7% in the primary group.

CONCLUSION

Beighton score, quadriceps circumference side-to-side difference, family history of ACL tear, lateral posterior tibial slope, anterolateral tibial subluxation, and anteromedial tibia subluxation were all significantly different between primary and revision ACLR groups. In addition, there was a high rate of tunnel malposition in the revision ACLR group.

Editorial Commentary: Respect the Posterior Tibial Slope and Make Slope-Reducing Osteotomies an Integral Part of the Surgical Repertoire

The posterior tibial slope (PTS), as part of the complex 3-dimensional bony knee morphology, has been a topic of interest for many years but has recently become a hot topic in the scope of reconstructive knee ligament surgery. Biomechanical and clinical evidence suggests that the PTS is an independent and well-accepted risk factor for primary and recurrent anterior cruciate ligament (ACL) injuries. As part of an individualized approach to anatomic ACL reconstruction, the PTS should be respected, and if necessary, addressed, which is especially true for the treatment of multiple failed ACL reconstructions.

Steep Posterior Tibial Slope and Excessive Anterior Tibial Translation Are Predictive Risk Factors of Primary Anterior Cruciate Ligament Reconstruction Failure: A Case-Control Study With Prospectively Collected Data

BACKGROUND

Steep posterior tibial slope (PTS) and excessive anterior tibial translation (ATT) have been identified as important anatomic risk factors for anterior cruciate ligament (ACL) injury, which have raised concerns about clinical outcomes after primary ACL reconstruction (ACLR).

PURPOSE

To investigate anatomic risk factors of primary ACLR failure and to determine the cutoff values of PTS and ATT for predicting primary ACLR failure.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Between November 2015 and May 2017, a total of 215 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Among them, 25 patients who showed complete discontinuity of ACL fibers on final follow-up magnetic resonance imaging scans were allocated into the failure group (study group). They were matched 1:2 to 50 control participants who showed clear and continuous ACL fibers on magnetic resonance imaging scans (control group). PTS and ATT were measured on preoperative weightbearing whole leg lateral radiographs and compared between the groups. The cutoff values of PTS and ATT for predicting primary ACLR failure were determined by the receiver operating characteristic curve. Moreover, predictors of primary ACLR failure were assessed by multivariate logistic regression analysis, including sex, age, body mass index, concomitant meniscal tears, degree of pivot-shift test, and KT-1000 arthrometer side-to-side difference, PTS, and ATT.

RESULTS

PTS and ATT values in the study group were significantly higher than those in the control group (mean ± SD: PTS, 17.2°± 2.2° vs 14.4°± 2.8°; ATT, 8.3 ± 3.4 mm vs 4.1 ± 3.1 mm; P < .001). The cutoff values of PTS and ATT for predicting primary ACLR failure were 17° (sensitivity, 66.7%; specificity, 90.9%) and 6 mm (sensitivity, 87.5%; specificity, 79.5%), respectively. Additionally, PTS ≥17° (odds ratio, 15.6; 95% CI, 2.7-91.5; P = .002) and ATT ≥6 mm (odds ratio, 9.9; 95% CI, 1.9-51.4; P = .006) were determined to be risk factors of primary ACLR failure, whereas sex, age, body mass index, concomitant meniscal tears, degree of the pivot-shift test, and KT-1000 arthrometer side-to-side difference were not.

CONCLUSION

In this study, PTS ≥17° and ATT ≥6 mm, as measured on weightbearing whole leg radiographs, were identified to be predictive risk factors of primary ACLR failure. This study adds to the existing knowledge about potential surgical indications of simultaneous slope-reducing high tibial osteotomy to mitigate the primary ACLR failure rate.

Influence of Posterior Tibial Slope on Clinical Outcomes and Survivorship After Anterior Cruciate Ligament Reconstruction Using Hamstring Autografts: A Minimum of 10-Year Follow-Up

PURPOSE

To investigate the influence of medial and lateral posterior tibial slope (PTS) on long-term clinical outcomes and survivorship after anterior cruciate ligament (ACL) reconstruction using hamstring autografts.

METHODS

A total of 232 patients (mean age, 28.2 ± 8.9 years) who underwent primary ACL reconstruction from October 2002 to July 2007 were retrospectively reviewed. Patients with multiple ligament reconstruction, total meniscectomy, contralateral knee surgery before ACL reconstruction, open growth plate, and less than 10-year follow-up were excluded in the study. The medial and lateral PTS were measured from preoperative magnetic resonance imaging. Based on Li et al.'s previous study, the patients were divided into 2 groups according to their medial PTS (≤5.6° vs >5.6°) and lateral PTS (≤3.8° vs >3.8°), respectively. Clinical outcomes (clinical scores, stability tests and failure rate) were compared between the groups at the last follow-up. Furthermore, survival analysis was performed using the Kaplan-Meier method.

RESULTS

All clinical scores (International Knee Documentation Committee subjective, Lysholm, and Tegner activity scores) and stability tests (physical examinations and side-to-side difference in Telos stress radiographs) were insignificantly different between the 2 groups classified based on medial or lateral PTS. However, the failure rate was significantly higher in patients with medial PTS >5.6° (16.1% vs 5.1%, P = .01) or lateral PTS >3.8° (14.5% vs 4.7%; P = .01). The odds ratios of graft failure due to increased medial and lateral PTS were 3.18 (95% confidence interval, 1.22-8.28; P = .02) and 3.43 (95% confidence interval, 1.29-9.09; P = .01), respectively. In addition, the 10-year survivorship was significantly lower in patients with medial PTS >5.6° (83.9% vs 94.9%, P = .01) or lateral PTS >3.8° (85.5% vs 96.0%; P = .01).

CONCLUSIONS

Increased medial (>5.6°) and lateral (>3.8°) PTS were associated with higher failure rate and lower survivorship at a minimum of 10-year follow-up after primary ACL reconstruction using hamstring autografts.

LEVEL OF EVIDENCE

Level III, retrospective comparative trial.

Correlation between notch width index assessed via magnetic resonance imaging and risk of anterior cruciate ligament injury: an updated meta-analysis

PURPOSE

To analyze the correlation between notch width index (NWI) and/or femoral intercondylar notch width (NW) assessed by magnetic resonance imaging (MRI) and risk of anterior cruciate ligament (ACL) injury.

METHODS

We searched the PubMed, Embase, China National Knowledge Infrastructure and Wanfang databases for literature reporting a correlation between ACL injury and NWI and/or NW. Subgroup analyses were stratified by ethnicity, sex and control source. The weighted mean difference (WMD) and 95% confidence intervals (95% CIs) were calculated for the ACL injury cases and controls using random- or fixed-effects models. Begg's test and sensitivity analyses were applied to assess publication bias and stability of the results, respectively.

RESULTS

Twenty-eight eligible studies were finally enrolled. The NW was significantly narrowerin the ACL injury cases than in the control cases (pooled WMD, - 1.88 [95% CI, - 2.43 to - 1.32]). The results were similar when stratified by ethnicity and sex. Similarly, the NWI was lower in ACL injury cases than in the controls. Asian populations presented similar results when stratified by ethnicity, among the self-control group when stratified by control source, and among men when stratified by sex. No publication bias was identified; however, the sensitivity analysis suggested unstable results in the NWI subgroup analysis.

CONCLUSIONS

The current meta-analysis evidenced that the NW assessed via MRI was significantly smaller in ACL injury cases than in the controls. The NWI was lower in ACL injury cases among men. Prevention strategies for ACL injury could be applied for people with intercondylar notch stenosis.

The role of anterolateral augmentation in primary ACL reconstruction

The anterolateral soft tissue envelope of the knee has long been recognised as a key stabilising structure. Once the mainstay of operative management of anterior cruciate ligament (ACL) rupture, interest in the area fell away with the advent of intraarticular arthroscopic reconstruction. Renewed interest in these structures together with cadaveric data evidencing the potential for restoration of near normal knee biomechanics following ACL and anterolateral soft tissue reconstruction has driven current concepts and development of operative techniques. Options for current anterolateral augmentation techniques in primary ACL reconstruction plus patient selection considerations are reviewed, together with an outlook at future research key to development of this area.

The Influences of Chronicity and Meniscal Injuries on Pivot Shift in Anterior Cruciate Ligament-Deficient Knees: Quantitative Evaluation Using an Electromagnetic Measurement System

PURPOSE

To investigate the influences of time from injury to surgery and meniscal injuries on knee rotational laxity in anterior cruciate ligament (ACL)-deficient knees using the electromagnetic system retrospectively.

METHODS

Ninety-four unilateral ACL-injured patients (44 male and 50 female, mean age: 27.3 ± 11.8 years) were included. The pivot-shift test was performed before ACL reconstruction, as was a quantitative evaluation using the electromagnetic system to determine tibial acceleration. Patients were divided into 4 groups according to the chronicity: group 1, within 3 months (22 patients); group 2, between 3 and 6 months (29 patients); group 3, between 6 and 12 months (23 patients); and group 4, more than 12 months (20 patients). The presence of meniscal injuries was examined arthroscopically.

RESULTS

The tibial acceleration was significantly greater in group 4. There was a positive correlation between tibial acceleration and the time from injury to surgery (r = 0.47, P = .02). In groups 1, 2 and 3, the tibial acceleration in patients with a lateral meniscal injury was significantly greater than in patients with a medial meniscal injury and without meniscal injury. When patients with lateral meniscal injury were excluded (leaving those with medial meniscus injury or without meniscal injury), group 4 had significantly greater accelerations than other groups.

CONCLUSIONS

In ACL-deficient knees, rotational laxity increased with time and the increased rotational laxity was evident more than 1 year after injury whereas it increased with concomitant lateral meniscal injuries within 1 year after injury.

LEVEL OF EVIDENCE

Ⅳ, diagnostic study of nonconsecutive patients.

Knee Morphological Risk Factors for Anterior Cruciate Ligament Injury: A Systematic Review

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction incidence has increased substantially in the past 25 years. Recently, there has been a focus on knee morphology as a contributor to ACL injury risk. The purpose of this study was to systematically review the literature to assess the influence of knee morphology on ACL injury.

METHODS

In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, PubMed, Embase, and MEDLINE were searched in September 2017 for studies reporting on knee morphology and ACL injury. The search was updated in June 2018. The following inclusion criteria were used: English language; full text available; Level-I, II, or III evidence; human studies; and skeletally mature patients.

RESULTS

After systematically screening 6,208 studies, 65 studies met the inclusion/exclusion criteria. Three additional studies were identified in the search update, for a total of 68 studies comprising 5,834 ACL-injured knees. Intercondylar notch stenosis, most commonly defined by an "A-shaped" notch, decreased notch width, or decreased notch width index, was the most commonly reported femoral morphological risk factor for ACL injury. Increased femoral condylar offset ratio (>63%) and decreased condylar radius of curvature also were associated with an increased risk of ACL injury. Increased medial and lateral tibial slopes were the most commonly reported tibial risk factors. A smaller tibial eminence, reduced ACL size, and poor tibiofemoral congruity were also associated with increased injury risk.

CONCLUSIONS

Intercondylar notch stenosis, variations in sagittal condylar shape, increased tibial slope, reduced tibial eminence size, poor tibiofemoral congruity, and reduced ACL size are substantial risk factors for ACL injury. In future research, it would be valuable to identify a slope beyond which slope correction should be performed concomitantly with ACL reconstruction, and to determine whether an optimal relationship of notch size to graft size exists. To achieve optimal outcomes, the osseous morphological risk factors should be considered in individualized anatomic ACL reconstructions.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Prevalence of knee injuries among male college students in Riyadh, Kingdom of Saudi Arabia

BACKGROUND

The knee is considered the most common injured joint between young sport participants. However, there is lack of proper prevalence estimation in our population. The purpose of this study was to identify the prevalence of knee injuries among male college students and to observe the demographic data associated with it. Our secondary objective was to evaluate the awareness and knowledge about these injuries.

METHODS

This is a cross-sectional study. A survey was distributed to collect the data among male college students, King Saud University, Riyadh, Saudi Arabia. Out of 688 students who participated and completed the questionnaire, a total of 482 were considered valid and met the inclusion criteria. Data were analyzed using Statistical Package for Social Sciences (SPSS).

RESULTS

The overall prevalence of knee injury was 23.2% (n = 112). Most of them injured during sport activities especially soccer and 68.7% involved in a non-contact mechanism of injury. Among those who went to a hospital mostly were diagnosed as contusion (31.4%) then as meniscus tear, ACL, and collateral ligament injury, respectively. Majority was treated conservatively and only 10.7% needed surgery surprisingly. There was no statistically significant difference between those who are injured and whether they were warmed up and stretched or not (P = 0.619). Low level of knowledge about knee injuries was noticed among the participants 57.7%.

CONCLUSION

Our study has highlighted the high prevalence of knee injuries and the need to raise the level of awareness and knowledge about these injuries in our population. Soccer was the most common sport associated with knee injuries; most of these injuries were treated conservatively.

Increased Posterior Tibial Slope in Patients With Osgood-Schlatter Disease: A New Association

BACKGROUND

Osgood-Schlatter disease (OSD) is a traction apophysitis of the tibial tubercle caused by repetitive strain and chronic avulsion from the patellar tendon. No widely accepted anatomic risk factors have been associated with OSD.

PURPOSE

To determine if OSD is associated with increased posterior tibial slope (PTS).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Forty knees with OSD and 32 control knees examined by the senior author between 2008 and 2019 were included. Patients 10 to 15 years of age with a clinical diagnosis of OSD and available lateral radiograph and magnetic resonance imaging (MRI) were eligible. Age- and sex-matched patients with a history of knee pain but no evidence of OSD on clinical examination and without significant pathology on lateral radiograph and MRI were included in the control group. PTS was defined as the angle between a reference line perpendicular to the proximal anatomic axis and a line drawn tangent to the uppermost anterior and posterior edges of the medial tibial plateau. Measurements were carried out in duplicate on true lateral radiographs by 2 blinded investigators. Interrater reliability of PTS measurements was evaluated using intraclass correlation coefficient (ICC). The independent samples t test was used to compare PTS between the OSD and control knees.

RESULTS

The mean age was 12.6 ± 1.6 years and 51% (37/72) of the knees were from male youth. There were no differences in age, sex, and laterality of knees between the OSD and control groups. The mean PTS was significantly higher in the OSD group (12.23°± 3.58°) compared with the control group (8.82°± 2.76°; P < .001). The ICC was 0.931 (95% CI, 0.890-0.957), indicating almost perfect interrater reliability.

CONCLUSION

This study identifies an association between OSD and increased PTS. The clinical implications of this finding have not yet been elucidated. It may be speculated that in patients with OSD, stress from the extensor mechanism through the patellar tendon loads the anterior portion of the tibia disproportionately to the posterior segment, thereby resulting in asymmetric growth and an increased PTS.

Diagnosis and treatment of rotatory knee instability

BACKGROUND

Rotatory knee instability is an abnormal, complex three-dimensional motion that can involve pathology of the anteromedial, anterolateral, posteromedial, and posterolateral ligaments, bony alignment, and menisci. To understand the abnormal joint kinematics in rotatory knee instability, a review of the anatomical structures and their graded role in maintaining rotational stability, the importance of concomitant pathologies, as well as the different components of the knee rotation motion will be presented.

MAIN BODY

The most common instability pattern, anterolateral rotatory knee instability in an anterior cruciate ligament (ACL)-deficient patient, will be discussed in detail. Although intra-articular ACL reconstruction is the gold standard treatment for ACL injury in physically active patients, in some cases current techniques may fail to restore native knee rotatory stability. The wide range of diagnostic options for rotatory knee instability including manual testing, different imaging modalities, static and dynamic measurement, and navigation is outlined. As numerous techniques of extra-articular tenodesis procedures have been described, performed in conjunction with ACL reconstruction, to restore anterolateral knee rotatory stability, a few of these techniques will be described in detail, and discuss the literature concerning their outcome.

CONCLUSION

In summary, the essence of reducing anterolateral rotatory knee instability begins and ends with a well-done, anatomic ACL reconstruction, which may be performed with consideration of extra-articular tenodesis in a select group of patients.

Multivariable analysis of anatomic risk factors for anterior cruciate ligament injury in active individuals

OBJECTIVE

The aim of the present study was to compare the morphometric differences between patients with or without anterior cruciate ligament (ACL) injury, and identify the anatomic risk factors associated with ACL injury in active individuals.

METHODS

The knee joint magnetic resonance images (MRI) of 100 subjects were included in this study. Data from the ACL-injured group (50 patients) and matched controls (50 subjects) were obtained from the same hospital. These data were analyzed by univariable analysis or multivariable conditional logistic regression analysis to examine the effects of the following variables on the risk of suffering ACL injury for the first time: TT-TG distance, medial and lateral tibial slope, intercondylar notch width and depth, femur condylar width, lateral femoral condylar depth, notch width index (NWI), notch shape index (NSI), notch depth index (NDI), and cross-sectional area (CSA).

RESULTS

In the univariable analysis, the ACL-injured group had a larger TT-TG distance, increased medial and lateral tibial slope, narrower intercondylar notch width, deeper lateral femoral condylar depth, lesser NWI and NSI, and CSA when compared with the control group (P < 0.05). However, there were no significant between-group differences in intercondylar notch depth (P = 0.174), femur condylar width (P = 0.797), and NDI (P = 0.436). The multivariable analysis revealed that TT-TG distance [odds ratio (OR) = 1.37, 95% CI = 1.04-1.81, P = 0.028], medial tibial slope (OR = 1.30, 95% CI = 1.02-1.66, P = 0.036) and NWI (OR = 0.46, 95% CI = 0.24-0.91, P = 0.025) had significant multivariable associations with the sole independent risk of ACL injury.

CONCLUSION

Larger TT-TG distance, increased MTS, and lesser NWI are independent anatomic risk factors for active individuals with ACL injury.

LEVEL OF EVIDENCE

Case-control study; Level of Evidence, III.

The Combined Effect of Body Mass Index and Tibial Slope Angles on Anterior Cruciate Ligament Injury Risk in Male Knees: A Case-Control Study

Introduction:

Tibial slope angles (TSAs) have been identified as potential risk factors of anterior cruciate ligament (ACL) injury in the literature. A higher body mass index (BMI) might increase the risk of ACL tear because of greater axial compressive force. The aim of this study was to determine the relationship of these factors and the combined effect of BMI and TSA in determination of risk potential for ACL injury.

Methods:

The preoperative magnetic resonance (MR) images of 81 ACL-injured male knees and of 68 male individuals with no ACL injuries were evaluated by 2 radiologists to measure the TSA. The Mann-Whitney U-test was performed to indicate the significant difference in height, weight, and BMI values. The independent samples t-test was used to determine the differences between ACL-injured and non-injured groups regarding TSA values. Odds ratios were calculated by logistic regression tests, and receiver operating characteristics (ROC) curves revealed the area under the receiver operating characteristics curve (AUC) values to compare the relationships of these parameters with ACL injury.

Results:

Body mass index, lateral tibial slope (LTS), and medial tibial slope (MTS) were predictive of ACL risk injury. Body mass index alone had the greatest effect among these parameters, and there were no statistically significant differences in coronal tibial slope values between the ACL-ruptured and control groups. The greatest AUC was observed for the combination of BMI, MTS, and LTS.

Conclusions:

Body mass index, LTS, and MTS angles were associated with ACL injury risk and BMI + MTS + LTS together revealed the greatest effect on ACL injury.

Steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant posterolateral meniscus root tears in anterior cruciate ligament injuries

PURPOSE

To compare sagittal and coronal tibial slopes between anterior cruciate ligament (ACL) injured subjects with and without posterolateral meniscus root tear (PLRT).

METHODS

A chart review was conducted to identify patients with isolated ACL tears and patients with an associated PLRT. Patients with other concomitant injuries and patients who underwent surgery > 6 months after the injury were excluded. Magnetic resonance image data were used to compare the medial and lateral sagittal tibial slope (MTS and LTS), lateral-to-medial slope asymmetry (LTS-MTS), and coronal slope of the tibial plateau between both groups. Mean LTS and standard deviation (SD) of the control group were calculated, and a value of > mean + 1 SD was considered an abnormal LTS. Interobserver reproducibility was assessed by calculating interclass correlation coefficients (ICCs) of measurements independently obtained by two reviewers.

RESULTS

Fifty-nine patients met the in- and exclusion criteria. Thirty nine (66%) had an isolated ACL tear and 20 (34%) had an associated PLRT. Interrater ICCs for LTS, MTS, and coronal slope were 0.930, 0.884 and 0.825, respectively, representing good to excellent interobserver reproducibility. Patients with a PLRT had significantly steeper LTS (8.0 ± 3.2 vs. 4.0 ± 2.0; p < 0.001) and significantly greater difference of LTS-MTS (3.7 ± 2.9 vs. - 0.6 ± 2.0; p < 0.001). Furthermore, patients with abnormal LTS were significantly overrepresented among patients with PLRT (70% vs. 18%; p < 0.001). No significant difference between both groups was found for MTS and coronal slope.

CONCLUSION

A steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant PLRT in ACL-injured subjects.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Anatomical Risk Factors of Anterior Cruciate Ligament Injury

Background:

Nowadays, the anterior cruciate ligament (ACL) injury has been one of the most common diseases of the knee joint. The relationships between the ACL injury and the anatomical structures are still controversial. This study aimed to identify the anatomical risk factors of ACL injury by magnetic resonance imaging (MRI) of the knee.

Methods:

This was a retrospective study of 125 patients undergoing primary ACL reconstruction between July 2013 and May 2017. Another 125 patients without any organic knee joint injury were served as controls. The shape of intercondylar notch, the intercondylar notch width index, the intercondylar notch height index, the α angle, the β angle, and the medial and lateral tibial plateau slope were measured with MRI and compared. The data were compared by binary logistic regression to find the risk factors.

Results:

The two groups differed in the proportion of male patients (70.4% vs. 52.0%, χ² = 8.911, P = 0.003), but gender was excluded as a risk factor for ACL injury with regression analysis (odds ratio = 1.476, 95% confidence interval [CI]: 0.689–3.160, P = 0.317). The injured group was found to have a smaller notch width index (95% CI = 7.960E-23–2.154E-9, P < 0.001), a larger β angle (95% CI = 1.311–1.785, P < 0.001), and a larger lateral tibial plateau slope (95% CI = 1.201–1.683, P < 0.001). The cutoff values of notch width index, β angle, and the lateral tibial plateau slope were 0.252, 38.5°, and 7.5°, respectively.

Conclusions:

In this study, a narrow intercondylar notch (intercondylar notch width index <0.252), a larger lateral tibial slope (>7.5°), and larger β angle (>38.5°) might be the factors associated with ACL injury.

Trial Registration:

ChiCTR-RRC-17014116; http://www.chictr.org.cn/showproj.aspx?proj=24119 .

Relationship between intercondylar notch angle and anterior cruciate ligament injury: a magnetic resonance imaging analysis

OBJECTIVES

This study was performed to compare the intercondylar notch angle (INA) and tibial slope in patients with and without anterior cruciate ligament (ACL) injury and determine the risk factors and influence of these anatomic variations on ACL injury.

METHODS

Participants with and without non-contact ACL injuries were included in the patient and control groups, respectively. The INA (formed by the femoral axis and Blumensaat line), lateral tibial slope (LTS), and medial tibial slope (MTS) were measured on magnetic resonance images. Comparisons were performed between the two groups. A binary logistic regression model was used to determine the influence of the variables on ACL injury.

RESULTS

Fifty-two participants were included in each group. The INA was significantly smaller and the LTS was significantly greater in the patients than in the controls. No difference was found in the MTS between the two groups. The area under the receiver operating characteristic curve for the combination of the INA and LTS was 0.776 (95% confidence interval, 0.688-0.864).

CONCLUSIONS

The INA was smaller and the LTS was greater in patients with than without ACL tears. The INA in combination with the LTS could be used to predict ACL injury.

Static Lateral Tibial Plateau Subluxation Predicts High-Grade Rotatory Knee Laxity in Anterior Cruciate Ligament-Deficient Knees

BACKGROUND

In anterior cruciate ligament-deficient (ACL-D) knees, injury pattern and bony morphologic features have been shown to influence both static anterior tibial subluxation relative to the femur and dynamic rotatory knee laxity. Therefore, the relationship between static anterior tibial subluxation and dynamic rotatory knee laxity was investigated.

PURPOSE

To determine whether static tibial subluxation as measured on magnetic resonance imaging (MRI) is associated with the grade of rotatory knee laxity in ACL-D knees.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Two-hundred fifty-eight knees underwent preoperative, image-guided assessment of lateral knee compartment translation during quantitative pivot shift (QPS). Subluxations of the medial and lateral tibial plateaus were measured on preoperative MRI in a subset of primary ACL-D knees meeting criteria for high-grade (QPS > 5.2 mm) and low-grade (QPS < 2.4 mm) rotatory laxity. Tibial subluxations on MRI were compared between patients with high- and low-grade rotatory laxity through use of pairwise t test and were analyzed via univariate and multivariate logistic regression. Significance was set at P < .05.

RESULTS

On MRI, greater anterior subluxation of the lateral tibial plateau was observed in patients with high-grade compared with low-grade rotatory knee laxity (4.5 mm vs 2.3 mm; P < .05). No similar relationship was observed for the medial tibial plateau (-0.9 mm vs -0.4 mm; P > .05). Univariate logistic regression demonstrated that static subluxation of the lateral tibial plateau was associated with high-grade rotatory knee laxity (odds ratio [OR], 1.2; P < .05). An optimal cutoff of 2.95 mm of static lateral tibial subluxation was associated with high-grade rotatory knee laxity (sensitivity, 75%; specificity, 63%). Lateral meniscal injury was the first variable entered into a multivariate regression analysis and proved to be most associated with high-grade rotatory knee laxity (OR, 6.8; P < .05). When lateral meniscal injury was excluded from multivariate regression analysis, static anterior subluxation of the lateral tibial plateau alone was associated with high-grade rotatory knee laxity (OR, 1.2; P < .05).

CONCLUSION

Data from this MRI study of two distinct rotatory knee laxity groups showed that static anterior subluxation of the lateral tibial plateau of 2.95 mm or greater was associated with high-grade rotatory knee laxity, and each millimeter increase of lateral tibial plateau subluxation was associated with a 1.2-fold odds of high-grade rotatory knee laxity. Anterior subluxation of the lateral tibial plateau on MRI was not independently associated with high-grade rotatory knee laxity in the presence of concomitant lateral meniscal injury. Static measurements made preoperatively may aid in predicting high-grade rotatory knee laxity and refining the indications for individualized knee surgery.

External loads associated with anterior cruciate ligament injuries increase the correlation between tibial slope and ligament strain during in vitro simulations of in vivo landings

BACKGROUND

The aim of the present study was to evaluate the relationship between tibial slope angle and ligament strain during in vitro landing simulations that induce ACL failure through the application of variable external loading at the knee. The hypothesis tested was that steeper posterior tibial slope angle would be associated with higher ACL strain during a simulated landing task across all external loading conditions.

METHODS

Kinetics previously derived from an in vivo cohort performing drop landings were reproduced on 45 cadaveric knees via the mechanical impact simulator. MRIs were taken of each specimen and used to calculate medial compartment posterior tibial slope, lateral compartment posterior tibial slope, and coronal plane tibial slope. Linear regression analyses were performed between these angles and ACL strain to determine whether tibial slope was a predictive factor for ACL strain.

FINDINGS

Medial and lateral posterior tibial slope were predictive factors for ACL strain during some landings with higher combined loads. Medial posterior slope was more predictive of ACL strain in most landings for male specimens, while lateral posterior and coronal slope were more predictive in female specimens, but primarily when high abduction moments were applied.

INTERPRETATION

Tibial slope has the potential to influence ACL strain during landing, especially when large abduction moments are present at the knee. Deleterious external loads to the ACL increase the correlation between tibial slope and ACL strain, which indicates that tibial slope angles are an additive factor for athletes apt to generate large out-of-plane knee moments during landing tasks.

Increased medial and lateral tibial posterior slopes are independent risk factors for graft failure following ACL reconstruction

PURPOSE

To analyze the contribution of increased lateral (LTPS) and medial tibial slopes (MTPS) as independent risk factors of graft failure following anterior cruciate ligament (ACL) reconstruction.

MATERIALS AND METHODS

Fifty-seven patients with graft failure after ACL reconstruction who underwent revision surgery between 2009 and 2014 were enrolled and matched to a control group of 69 patients with primary anatomic successful ACL reconstruction. Patients were matched based on age, sex, date of primary surgery and graft type. LTPS and MTPS were measured on MRI in a blinded fashion. Tibial and femoral tunnel positions were determined on CT scans. Independent t test was used to compare the MTPS and LTPS between subgroups. Risks of graft failure associated with an increasing MTPS and LTPS were analyzed using binary logistic analysis.

RESULTS

The means of LTPS (7.3°) and MTPS (6.7°) in the graft failure group were found to be significantly greater than in the control group (4.6° and 4.1°, respectively; p = < 0.001). Non-anatomic and anatomic tunnel positions were found in 42 cases (73.7%) and 15 cases (26.3%), respectively. There were no significant differences in MTPS or LTPS between patients with anatomic and non-anatomic tunnel positions within the graft failure group. An increase of the MTPS of 1° was associated with an 1.24 times increased likelihood of exhibiting graft failure [95% CI 1.07-1.43] (p = 0.003) and an increase of the LTPS of 1° was associated with an 1.17 times increased likelihood of exhibiting graft failure [95% CI 1.04-1.31] (p = 0.009). The increased risk was most evident in patients with a lateral tibial posterior slope of ≥ 10°.

CONCLUSIONS

Increased LTPS and MTPS are independent risk factors for graft failure following ACL reconstruction regardless whether tunnel position is anatomic or non-anatomic. This information may be helpful to clinicians when considering slope correction in selected revision ACL reconstruction procedures.

Anterior Closing-Wedge Osteotomy for Posterior Slope Correction

Increased tibial slope can be a cause of recurrent instability after anterior cruciate ligament reconstruction. This article presents a technique for an anterior closing-wedge osteotomy for slope correction. The indications for this procedure are patients with recurrent instability after anterior cruciate ligament reconstruction with a neutral leg axis or slightly varus deformity and a posterior slope of more than 12°. The exposure of the anterior aspect of the tibia is best made through an anterior approach approximately 1 to 2 cm medial to the tibial tuberosity. Hohmann retractors are placed from the medial and lateral sides behind the proximal tibia. The osteotomy lines are marked with 2 converging Kirschner wires with the use of an image intensifier. The entry point of the first Kirschner wire is just below the most inferior fibers of the patellar tendon. The hinge of the osteotomy should be just below the tibial insertion of the posterior cruciate ligament. The osteotomy is performed with an oscillating saw. The posterior cortex of the tibia should be left intact. After removal of the anterior base wedge, the osteotomy is closed by manual pressure. Osteosynthesis is performed with a lag screw from the tibial tuberosity to the distal tibia and an angular stable plate fixator.

Bone morphology and morphometry of the lateral femoral condyle is a risk factor for ACL injury

PURPOSE

The purpose of this study was to investigate the influence of the knee lateral compartment bony morphology and morphometry on risk of sustaining an anterior cruciate ligament (ACL) injury.

METHODS

A total of 400 age and sex-matched patients (200 ACL-ruptured and 200 ACL-intact) were included. The lateral femoral and tibial bone morphology and morphometric parameters were measured on knee lateral radiographs, taken at 30° of knee flexion with overlapping of the femoral condyles. Radiographic measurements included: anteroposterior-flattened surface of the femur's lateral condyle (XY); femur's diaphysis anteroposterior distance (A); anteroposterior distance of the femur's lateral condyle (B); height of the femur's lateral condyle (C); anteroposterior distance of the tibial plateaus (AB); tibial slope. In addition, three morphological ratios were calculated: B/AB; B/XY; XY/AB (Porto ratio).

RESULTS

Most of bone morphological parameters were different between genders (P < 0.05). ACL-ruptured female subjects showed statistical significant smaller condyle heights (C), smaller distances of the flattened surface of the distal femoral condyle (XY), smaller tibial plateau anteroposterior distances (AB), and higher XY/AB ratio (P < 0.05). ACL-ruptured male subjects had statistical significant smaller condyle height (C), anteroposterior distance of the femur's lateral condyle (B), tibial plateau anteroposterior distances (AB), and tibial slope (P < 0.05). Multivariate logistic regression model showed that five morphological parameters (A, XW, XY, XZ, and AB) were significantly associated with ACL rupture (AUC = 0.967, P < 0.001). Calculated ratios (XY/AB; B/AB; B/XY) showed a significant accuracy in identifying individuals with ACL injury (P < 0.001).

CONCLUSIONS

The most important finding of this study was that the calculated ratios (XY/AB; B/AB; B/XY) showed a significant accuracy in identifying the individuals with and without an ACL injury. Within this line, a longer flat surface of the lateral femoral condyle or higher Porto ratio (XY/AB) is associated with a lower the risk of ACL injury. Moreover, when considering the combination of five primary bone morphology and morphometric parameters (A, XW, XY, XZ, and AB), the accuracy in identifying these individuals was excellent (AUC = 0.967). These findings may contribute to injury risk assessment, sports participation, and injury prevention counseling and surgical planning refining by identifying high-risk patients who would benefit from the addition of associated procedures to the anatomic ACL reconstruction aiming the improvement of knee stability and decrease the risk of further injuries.

LEVEL OF EVIDENCE

III, case-control study.

Automated, accurate, and three-dimensional method for calculating sagittal slope of the tibial plateau

Increased posterior-inferior directed slope of the subchondral bone of the lateral tibial plateau is a risk factor for noncontact rupture of the anterior cruciate ligament (ACL). Previous measures of lateral tibial slope, however, vary from study to study and often lack documentation of their accuracy. These factors impede identifying the magnitude of lateral tibial slope that increases risk of noncontact ACL rupture. Therefore, we developed and evaluated a new method that (1) requires minimal user input; (2) employs 3D renderings of the tibia that are referenced to a 3D anatomic coordinate system; and (3) is precise, reliable, and accurate. The user first isolated the proximal tibia from computed tomography (CT) scans. Then, the algorithm placed the proximal tibia in an automatically generated tibial coordinate system. Next, it identified points along the rim of subchondral bone around the lateral tibial plateau, iteratively fit a plane to this rim of points, and, finally, referenced the plane to the tibial coordinate system. Precision and reliability of the lateral slope measurements were respectively assessed via standard deviation and intra- and inter-class correlation coefficients using CT scans of three cadaveric tibia. Accuracy was quantified by comparing changes in lateral tibial slope calculated by our algorithm to predefined in silico changes in slope. Precision, reliability, and accuracy were ≤0.18°, ≥0.998, and ≤0.13°, respectively. We will use our novel method to better understand the relationship between lateral tibial slope and knee biomechanics towards preventing ACL rupture and improving its treatment.