Is the femoral lateral condyle's bone morphology the trochlea of the ACL?

Editorial Commentary: Early Outcomes of Suture Tape Augmentation in Quadriceps Tendon Autograft Anterior Cruciate Ligament Reconstruction Are Promising but Require Long-term Proof

The management of anterior cruciate ligament (ACL) injuries continually evolves, with new interest in all-soft tissue quadriceps tendon autograft, as well as new interest in suture tape augmentation of the graft, particularly in high-risk patients with young age; female sex; lower-limb alignment, tibial, or femoral abnormalities; hyperlaxity; concomitant meniscal and/or additional ligamentous injuries; or participation in high-risk sports. Load-sharing suture tape enhances the biomechanical stability of the reconstructed ACL, especially during the initial ingrowth and ligamentization phase, and biomechanical evidence highlights a reduced risk of graft elongation and failure under the loads encountered during daily physical activities and sport. Optimal tape tensioning could be achieved in knee hyperextension, when the ACL is at maximal length, to avoid overconstraint. The published 2-year outcomes of this technique are excellent. Current comparative studies, however, have not shown superiority. Additional controlled studies and studies with longer-term follow-up are needed, as well as comparison to extra-articular tenodesis augmentation.

Increased Lateral Femoral Condyle Ratio Measured by Magnetic Resonance Imaging Is Associated With Anterior Cruciate Ligament Rerupture

PURPOSE

To investigate the association between lateral femoral condyle ratio (LFCR) measured by magnetic resonance imaging (MRI) and anterior cruciate ligament (ACL) rerupture after anatomic ACL reconstruction (ACLR) and to compare the diagnostic accuracy between MRI and radiograph measurements.

METHODS

A retrospective review was conducted on patients who underwent anatomic ACLR in our institution between 2015 and 2018. Patients who experienced rerupture after ACLR were identified and matched 1:1 with control patients who showed no evidence of graft failure during a minimum 48-month follow-up. The matching criteria included age, sex, and body mass index. LFCR was measured on MRI scans and radiographs of the affected limb. Patients' characteristics, surgical features, and anatomic measurements were compared between groups. Conditional logistic regression was performed to investigate whether MRI-measured LFCR is a risk factor for ACL rerupture. The optimal cutoff value was determined by receiver operating characteristic curves (ROC). Delong's test was performed to compare the diagnostic accuracy between MRI and radiograph measurements.

RESULTS

A total of 72 patients who sustained ACL rerupture were included and matched with 72 control subjects. Compared to patients with intact ACLR, those who sustained ACL rerupture showed a significant increase in LFCR on MRI scans (63.38% ± 2.26% [95% CI, 62.84%-63.91%] vs 61.10% ± 2.19% [95% CI, 60.59%-61.61%], P < .001). An MRI-measured LFCR >62.18% was set as the cutoff point to discern patients at a higher risk of graft failure after anatomic ACLR, with sensitivity and specificity of 75.0% and 70.8%, respectively. MRI-measured LFCR demonstrated superior diagnostic accuracy during ROC curve analysis, achieving a higher area under the curve compared to radiograph-measured LFCR (0.783 ± 0.051 vs 0.668 ± 0.060, P = .041).

CONCLUSIONS

The study found that MRI-measured LFCR was associated with ACL rerupture. A cutoff value of 62.18% was determined, which can help identify patients at a higher risk of rerupture.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Association of Increased Lateral Femoral Condylar Ratio With Lateral Meniscus Posterior Root Tear in Noncontact ACL Injury

Background

In the setting of anterior cruciate ligament (ACL) injury, lateral meniscus posterior root tears (LMPRTs) are less readily diagnosed on preoperative magnetic resonance imaging (MRI). Therefore, to predict LMPRTs in ACL injuries, it is necessary to understand the risk factors associated with them.

Purpose/Hypothesis

The purpose of this study was to investigate the association of lateral femoral condylar ratio (LFCR) with LMPRTs in ACL injuries. It was hypothesized that an increased LFCR would be associated with LMPRTs in noncontact ACL injuries.

Study Design

Cohort study; Level of evidence, 3.

Methods

Enrolled were consecutive patients who underwent primary acute (<6 weeks from injury) ACL reconstruction after noncontact injury and had LMPRT confirmed on preoperative MRI and arthroscopically (combined group; n = 62) as well as patients who underwent isolated acute ACL reconstruction (isolated group; n = 80) who were matched to the combined group by age, height, and body mass index (BMI). All patients underwent surgery between January 1999 and November 2021. LFCR and posterior tibial slope (PTS) were measured and compared between the isolated and combined groups. The area under the receiver operating characteristic curve (AUC) was calculated to determine the cutoff for detecting increased risk of LMPRTs.

Results

The demographic characteristics of the 2 groups did not differ significantly, nor did the PTS. The LFCR was a significant factor (odds ratio [OR], 1.23; P = .001) associated with LMPRT. Patient age, height, BMI, and PTS were not associated with LMPRT. The AUC (0.66; 95% CI, 0.57-0.75) for LFCR had a sensitivity of 39% and specificity of 90% to predict LMPRT. The calculated cutoff associated with an increased risk for LMPRT when compared with the isolated group was 67.0% (OR, 4.98; 95% CI, 2.10-11.79).

Conclusion

Increased LFCR was associated with the presence of LMPRTs in patients with acute ACL injuries. The LFCR may provide surgeons with additional information regarding the risk of having a concomitant LMPRT when planning ACL reconstructions.

Increased lateral femoral condyle ratio measured by MRI is associated with higher risk of solitary meniscus injury

Background: Past studies found that an increased lateral femoral condyle ratio is associated with anterior cruciate ligament injuries, but it is not clear if there is a link between MRI-measured lateral femoral condyle ratios and meniscal injuries. MRI provides a more accurate selection of measurement planes. Compared to X-rays, it further reduces data errors due to non-standard positions. Objective: To study the relationship between knee bone morphology and Solitary meniscal injuries by MRI. Methods: A total of 175 patients were included in this retrospective case-control study, including 54 cases of pure medial meniscus injury, 44 cases of pure lateral meniscus injury as the experimental group, and 77 control subjects. MRI images were used to measure the femoral notch width, femoral condylar width, femoral notch width index, lateral femoral condylar ratio (LFCR), posterior tibial slope, medial tibial plateau depth, and meniscus slope. In addition, carefully check for the presence of specific signs such as bone contusions and meniscal extrusions. Comparing the anatomical differences in multiple bone morphologies between the two groups, a stepwise forward multifactorial logistic analysis was used to identify the risk factors for Solitary meniscal injuries. Finally, ROC curves were used to determine the critical values and best predictors of risk factors. Results: MTS, LTS, and LFCR ended up as independent risk factors for meniscus injury. Among all risk factors, LFCR had the largest AUC of 0.781 (0.714-0.848) with a threshold of 72.75%. When combined with MTS (>3.63°), diagnostic performance improved with an AUC of 0.833 (0.774-0.892). Conclusion: Steep medial tibial plateau slope, steep lateral tibial plateau slope angle, and deep posterior lateral femoral condyles on MRI are independent risk factors for meniscal injuries. In patients with knee discomfort with the above imaging findings (X-ray, MRI), we should suspect and carefully evaluate the occurrence of meniscal injuries. It not only provides a theoretical basis to understand the mechanism of meniscus injury but also provides theoretical guidance for the prevention of meniscus injury and the development of intervention measures. Level of evidence III.

Bone morphology features associated with knee kinematics may not be predictive of ACL elongation during high-demand activities

PURPOSE

Bony morphology has been proposed as a potential risk factor for anterior cruciate ligament (ACL) injury. The relationship between bony morphology, knee kinematics, and ACL elongation during high-demand activities remains unclear. The purpose of this study was to determine if bone morphology features that have been associated with ACL injury risk and knee kinematics are also predictive of ACL elongation during fast running and double-legged drop jump.

METHODS

Nineteen healthy athletes performed fast running and double-legged drop jump within a biplane radiography imaging system. Knee kinematics and ACL elongation were measured bilaterally after using a validated registration process to track bone motion in the radiographs and after identifying ACL attachment sites on magnetic resonance imaging (MRI). Bony morphological features of lateral posterior tibial slope (LPTS), medial tibial plateau (MTP) depth, and lateral femoral condyle anteroposterior width (LCAP)/lateral tibial plateau anteroposterior width (TPAP) were measured on MRI. Relationships between bony morphology and knee kinematics or ACL elongation were identified using multiple linear regression analysis.

RESULTS

No associations between bony morphology and knee kinematics or ACL elongation were observed during fast running. During double-legged drop jump, a greater range of tibiofemoral rotation was associated with a steeper LPTS (β = 0.382, p = 0.012) and a deeper MTP depth (β = 0.331, p = 0.028), and a greater range of anterior tibial translation was associated with a shallower MTP depth (β = - 0.352, p = 0.018) and a larger LCAP/ TPAP (β = 0.441, p = 0.005); however, greater ACL elongation was only associated with a deeper MTP depth (β = 0.456, p = 0.006) at toe-off.

CONCLUSION

These findings indicate that observed relationships between bony morphology and kinematics should not be extrapolated to imply a relationship also exists between those bone morphology features and ACL elongation during high-demand activities. These new findings deepen our understanding of the relationship between bony morphology and ACL elongation during high-demand activities. This knowledge can help identify high-risk patients for whom additional procedures during ACL reconstruction are most appropriate.

Bone Morphological Characteristics as Risk Factors for Anterior Cruciate Ligament Injury: Comparison Between Contact and Noncontact Injury

Background

Altered bone morphologies are considered risk factors for noncontact anterior cruciate ligament (ACL) injuries.

Purpose/Hypothesis

This study aimed to investigate bone morphological characteristics as risk factors for ACL tears in contact injuries and compare these factors with those for noncontact ACL injuries. We hypothesized that altered bone morphologies would also be risk factors for contact ACL injury.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Enrolled were patients who underwent primary ACL reconstructions between January 2000 and December 2021 within 6 weeks after injury. Patients in the ACL group were classified according to injury mechanism (contact vs noncontact). During the same period, a control group of patients matched by age, height, and body mass index to the ACL group was selected. The lateral femoral condylar ratio (LFCR), notch width index (NWI), and lateral posterior tibial slope (PTS) were measured. Measured parameters were compared between the control, contact, and noncontact groups using analysis of variance.

Results

There were 86 patients in the control group, 102 patients in the contact ACL group, and 105 patients in the noncontact ACL group. The demographic characteristics of the 3 groups did not differ significantly. The contact group had significantly higher LFCRs and lower NWIs compared with the control group (P < .001 and P = .001, respectively). The noncontact group had significantly higher LFCRs and PTSs and lower NWIs compared with the control group (P = .031; P < .001; and P < .001, respectively). The noncontact group had significantly higher PTSs and lower NWIs compared with the contact group (P = .003 and P =.014, respectively). In the contact group, the LFCR, PTS, and NWI were significant risk factors for ACL tears (odds ratio [OR], 1.25 [P < .001]; OR, 1.16 [P = .008]; and OR, 1.27 [P = .001], respectively), and in the noncontact group, the PTS and NWI were significant risk factors for ACL tears (OR, 1.20 [P < .001]; OR, 1.59 [P < .001], respectively).

Conclusion

Altered bone morphological characteristics of the knee were found to be risk factors for ACL tears in contact injuries as well as noncontact injuries. Altered morphology has a more significant effect in noncontact ACL injuries.

Combined Anterolateral Ligament and Anterior Cruciate Ligament Injury Is Associated With Increased Lateral Femoral Condyle Ratio

PURPOSE

to investigate the association between the lateral femoral condylar ratio (LFCR), the posterior tibial slope (PTS), and injury of the anterolateral ligament (ALL).

METHODS

Inclusion criteria were patients with acute anterior cruciate ligament (ACL) tear after noncontact injury during sports from October 1997 to May 2021. The LFCR and PTS were measured, and injury of the ALL was evaluated. Patients were divided into 2 groups: isolated ACL tear (isolated group) and combined ACL with ALL tear (combined group). The LFCR and PTS were compared between the isolated and combined groups. For each risk factor, the receiver operating characteristic curve, the area under the curve (AUC), and its 95% confidence interval (CI) were calculated to determine the cutoff for detecting increased risk of ALL injury.

RESULTS

There were 83 patients in the isolated group and 176 patients in the combined group. Demographics of the 2 groups did not differ significantly. The LFCR was significantly larger in the combined group than in the isolated group (P = .000). The PTS did not differ between the two groups (P = .405). The LFCR (odds ratio [OR] = 1.58; P = .000) was a significant factor. Age, body mass index, and PTS were not associated with an ALL injury. The AUC (0.79; 95% CI, 0.74-0.85) for the LFCR had a sensitivity of 73% and specificity of 76% to predict an ALL rupture. The calculated cutoff of 64.5 was associated with an increased risk for ALL rupture (OR = 8.65; 95% CI, 4.73-15.81) when compared with the isolated group.

CONCLUSIONS

An increased LFCR was associated with the ALL injury. However, increased PTS was not associated with ALL injury. These findings need to be considered for clinicians in treating ACL tear patients at risk for an ALL injury.

LEVEL OF EVIDENCE

III, retrospective comparative prognostic trial.

Femoral condyle configuration and its impact on anterior cruciate ligament reconstruction

BACKGROUND

Rupture of the anterior cruciate ligament (ACL) is one of the most common knee injuries and has substantial impact on knee function. Beside primary ruptures, an increasing number of re-(re-)ruptures occur, representing a therapeutical challenge for the treating surgeon. Several risk factors for re-ruptures have been previously identified, including an increased tibial slope.

OBJECTIVE

In this study, we investigated the effect of femoral condyle configuration on ACL-ruptures and re-ruptures.

METHODS

In-vivo magnetic resonance imaging scans of three different groups of patients were compared. Group 1 included patients with an intact ACL on both sides, group 2 included patients with primary, unilateral ACL-rupture, while group 3 included patients with an ACL-re-rupture or re-(re-)rupture. Fourteen different variables were obtained and analyzed regarding their impact on ACL-re-(re-)rupture.

RESULTS

Overall, 334 knees were investigated. Our data allowed us to define parameters to identify anatomical configurations of bones associated with an increased risk of ACL-re-rupture. Our results show, that patients with ACL-re-rupture show increased radii of the extension facet of the lateral femoral condyle (p< 0.001) as well as of the extension facet of the medial femoral condyle (p< 0.001).

CONCLUSION

We conclude that a spherical femoral condyle form does influence the clinical outcome after ACL-reconstruction.

The Clinical Application of Machine Learning Models for Risk Analysis of Ramp Lesions in Anterior Cruciate Ligament Injuries

BACKGROUND

Peripheral tears of the posterior horn of the medial meniscus, known as "ramp lesions," are commonly found in anterior cruciate ligament (ACL)-deficient knees but are frequently missed on routine evaluation.

PURPOSE

To predict the presence of ramp lesions in ACL-deficient knees using machine learning methods with associated risk factors.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

This study included 362 patients who underwent ACL reconstruction between June 2010 and March 2019. The exclusion criteria were combined fractures and multiple ligament injuries, except for medial collateral ligament injuries. Patients were grouped according to the presence of ramp lesions on arthroscopic surgery. Binary logistic regression was used to analyze risk factors including age, sex, body mass index, time from injury to surgery (≥3 or <3 months), mechanism of injury (contact or noncontact), side-to-side laxity, pivot-shift grade, medial and lateral tibial/meniscal slope, location of bone contusion, mechanical axis angle, and lateral femoral condyle (LFC) ratio. The receiver operating characteristic curve and area under the curve were also evaluated.

RESULTS

Ramp lesions were identified in 112 patients (30.9%). The risk for ramp lesions increased with steeper medial tibial and meniscal slopes, higher knee laxity, and an increased LFC ratio. Comparing the final performance of all models, the random forest model yielded the best performance (area under the curve: 0.944), although there were no significant differences among the models (P > .05). The cut-off values for the presence of ramp lesions on receiver operating characteristic analysis were as follows: medial tibial slope >5.5° (P < .001), medial meniscal slope >5.0° (P < .001), and LFC ratio >71.3% (P = .033).

CONCLUSION

Steep medial tibial and meniscal slopes, an increased LFC ratio, and higher knee rotatory laxity were observed risk factors for ramp lesions in patients with an ACL injury. The prediction model of this study could be used as a supplementary diagnostic tool for ramp lesions in ACL-injured knees. In general, care should be taken in patients with ramp lesions and its risk factors during ACL reconstruction.

Morphological Risk Factors for Posterior Cruciate Ligament Tear and Tibial Avulsion Injuries of the Tibial Plateau and Femoral Condyle

BACKGROUND

Identification of morphological risk factors associated with the knee that threaten ligaments is important for understanding injury mechanisms and prevention. However, the morphological risk factors for posterior cruciate ligament (PCL) lesions are not clearly understood.

PURPOSE

To investigate whether the medial tibial depth (MTD), medial and lateral posterior tibial slope, asymmetry of the medial and lateral slopes, radius of the sagittal plane medial femoral condyle, coronal tibial slope, and notch width index (NWI) were risk factors for PCL intrasubstance tearing (PCLIT) and tibial avulsion fractures (PCLAF).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Between January 2015 and March 2022, 82 patients with isolated PCLIT, 68 patients with isolated PCLAF, and 82 controls without any ligamentous or meniscal pathologic findings as determined via physical examination and magnetic resonance imaging were included. Values were compared among the 3 groups. Logistic regression analysis was performed to confirm the risk factors. Receiver operating characteristic curves were defined for the morphological indicators and combination of risk factors.

RESULTS

Logistic regression analysis revealed (1) MTD, lateral minus medial posterior tibial slope, radius of the posterior circle of the medial femoral condyle, and NWI as significant independent predictors for PCLIT and (2) MTD and NWI for PCLAF. The areas under the curve combining the 4 indicators for PCLIT and noncontact PCLIT were 0.79 (95% CI, 0.72-0.86) and 0.90 (95% CI, 0.85-0.96), respectively. The area under the curve for the combination of MTD and NWI for PCLAF was 0.78 (95% CI, 0.70-0.86).

CONCLUSION

Decreased MTD and NWI were associated with an increased incidence of PCLIT and PCLAF. Increased asymmetry of the medial and lateral slopes and the radius of the posterior circle of the medial femoral condyle were associated with the presence of PCLIT. In addition, the model of a combination of risk factors showed good predictive ability for noncontact PCLIT. These findings may aid clinicians in identifying patients at risk for PCL lesions. Further studies are warranted for identifying the effect of these factors on biomechanical mechanisms.

An Increased Lateral Femoral Condyle Ratio in Addition to Increased Posterior Tibial Slope and Narrower Notch Index Is a Risk Factor for Female Anterior Cruciate Ligament Injury

PURPOSE

To investigate the relationship between the lateral femoral condyle ratio (LFCR) among osseous morphologic characteristics of the knee and anterior cruciate ligament (ACL) injury in female patients.

METHODS

Inclusion criteria were female patients (ACL group, n = 59) undergoing primary ACL reconstruction from 2012 to 2018. Control female patients (control group, n = 58) were matched by age, height, and body mass index to ACL group. They had no meniscal or ligament tear, and no trochlear dysplasia on magnetic resonance imaging. The LFCR, notch width index (NWI), and posterior tibial slope (PTS) were measured and compared between the ACL and control groups. For each risk factor, the receiver operating characteristic curve and the area under the curve and its 95% confidence interval (CI) was calculated to determine the cutoff for detecting increased risk of ACL injury.

RESULTS

The LFCR was significantly larger in the knees in the ACL group than in the control group (P = .001). The NWI was significantly smaller and the PTS was significantly larger in the knees in the ACL group than in the control group (P = .000, P = .000, respectively). The NWI (odds ratio [OR] 1.41; P = .000) was the most significant factor, followed by the PTS (OR 1.29; P = .003) and the LFCR (OR 1.26; P = .001). The area under the curve (0.67, 95% CI 0.58-0.77) for the LFCR had a sensitivity of 66% and specificity of 66% to predict an ACL injury. The cutoff of 63.9 was associated with an increased risk for ACL injury (OR 3.71; 95% CI 1.73-7.95).

CONCLUSIONS

An increased LFCR was associated with female ACL injury. The LFCR, NWI, and PTS are predictive risk factors for an ACL injury. These findings need to be considered for clinician in identifying female patients at risk for an ACL injury.

LEVEL OF EVIDENCE

III, retrospective comparative prognostic trial.

Increased lateral femoral condyle ratio measured by MRI is associated with higher risk of noncontact anterior cruciate ligament injury

BACKGROUND

Studies have shown a significant association between the radiographically measured lateral femoral condyle ratio (LFCR) and anterior cruciate ligament (ACL) injury. However, it is unclear whether LFCR measured by magnetic resonance imaging (MRI) is associated with a higher risk of noncontact ACL injury.

OBJECTIVE

To investigate the effect of LFCR on the risk of noncontact ACL injury by MRI. 2 to investigate the association of LFCR measured by MRI with multiple bone morphological risk factors and evaluate the most sensitive risk predictors of noncontact ACL injury.

METHODS

A total of 116 patients, including 58 subjects with noncontact ACL injury and 58 age-matched and sex-matched controls with only meniscus injury, were included in this retrospective case-control study. LFCR, lateral tibial slope (LTS), lateral tibial height (LTH), medial tibial slope (MTS), and medial tibial depth (MTD) were measured on MRI. The differences in each index between the two groups were compared, and risk factors were screened by single-factor logistic regression analysis. Indicators with P values < 0.1 were included in the logistic regression equation. The critical values and areas under the curve (AUCs) of independent risk factors were determined by receiver operating characteristic (ROC) curve analysis. Finally, the diagnostic performance of each risk factor was evaluated by the Z-test.

RESULTS

A total of 116 patients who met the inclusion criteria were included in the final analysis (58 cases in the noncontact ACL injury group and 58 cases in the control group). Patients with noncontact ACL injury had a higher femoral LFCR (0.64 ± 0.03) than patients with isolated meniscus tears. Among all the risk factors for ACL injury, the AUC for LFCR was the largest, at 0.81 (95% CI, 0.73-0.88), and when the critical value was 0.61, the sensitivity and specificity for the diagnosis of ACL injury were 0.79 and 0.67, respectively. When combined with LTH (> 2.35 mm), the diagnostic performance was improved. The AUC was 0.85 (95% CI, 0.78-0.92), the sensitivity was 0.83, and the specificity was 0.76.

CONCLUSION

This study shows that an increased LFCR is related to an increased risk of noncontact ACL injury as determined by MRI. LFCR and LTH are sensitive risk factors for noncontact ACL injury and may help clinicians identify individuals prone to ACL injury, allowing prevention and intervention measures to be applied.

The Relationship Between Lateral Femoral Condyle Index and Noncontact Anterior Cruciate Ligament Rupture

Purpose

The purpose of this study was to examine the relationship between distal femoral morphology and noncontact anterior cruciate ligament (ACL) rupture and the differences between digital X-ray imaging systems (DR) and magnetic resonance imaging (MRI) to evaluate distal femoral morphology.

Methods

A retrospective case-control study was performed on 120 patients. Two age- and sex-matched cohorts (each n = 60) were analyzed: primary ACL ruptures and a control group consisting of isolated meniscal tears. The lateral femoral condyle index (LFCI) was measured by DR and by MRI to quantify femoral sphericity. Differences among two groups were compared, and diagnostic performance of the risk factors was assessed. In addition, differences between DR and MRI to evaluate LFCI were examined.

Results

The LFCI by MRI was smaller in the knees with primary ACL rupture (median, 0.71; range, 0.62–0.78) than that of the control group (median, 0.77; range, 0.66–0.85) (p < 0.01). The LFCI was also significantly smaller in the knees with primary ACL rupture (median, 0.72; range, 0.63–0.77) than that of the control group (median, 0.79; range, 0.65–0.84) (p < 0.01) by DR. A cutoff of 0.74 of MRI yielded a sensitivity of 77% and a specificity of 78% to predict an ACL rupture, and of 0.75 of DR yield a sensitivity of 87% and a specificity of 77% to predict an ACL rupture.

Conclusion

This study showed that a decreased LFCI is associated with an ACL rupture, and both DR and MRI measurements can effectively predict the risk of ACL rupture. This helps expand the scope of the application of the LFCI and helps clinicians identify susceptible individuals who may benefit from targeted ACL rupture prevention counseling and intervention.

Femoral and Tibial Bony Risk Factors for Anterior Cruciate Ligament Injuries Are Present in More Than 50% of Healthy Individuals

BACKGROUND

Anterior cruciate ligament (ACL) injuries are multifactorial events that may be influenced by morphometric parameters. Associations between primary ACL injuries or graft ruptures and both femoral and tibial bony risk factors have been well described in the literature.

PURPOSE

To determine values of femoral and tibial bony morphology that have been associated with ACL injuries in a reference population. Further, to define interindividual variations according to participant demographics and to identify the proportion of participants presenting at least 1 morphological ACL injury risk factor.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Computed tomography scans of 382 healthy participants were examined. The following bony ACL risk factors were analyzed: notch width index (NWI), lateral femoral condylar index (LFCI), medial posterior plateau tibial angle (MPPTA), and lateral posterior plateau tibial angle (LPPTA). The proportion of this healthy population presenting with at least 1 pathological ACL injury risk factor was determined. A multivariable logistic regression model was constructed to determine the influence of demographic characteristics.

RESULTS

According to published thresholds for ACL bony risk factors, 12% of the examined knees exhibited an intercondylar notch width <18.9 mm, 25% had NWI <0.292, 62% exhibited LFCI <0.67, 54% had MPPTA <83.6°, and 15% had LPPTA <81.6°. Only 14.4% of participants exhibited no ACL bony risk factors, whereas 84.5% had between 2 and 4 bony risk factors and 1.1% had all bony risk factors. The multivariate analysis demonstrated that only the intercondylar notch width (P < .0001) was an independent predictor according to both sex and ethnicity; the LFCI (P = .012) and MMPTA (P = .02) were independent predictors according to ethnicity.

CONCLUSION

The precise definition of bony anatomic risk factors for ACL injury remains unclear. Based on published thresholds, 15% to 62% of this reference population would have been considered as being at risk. Large cohort analyses are required to confirm the validity of previously described morphological risk factors and to define which participants may be at risk of primary ACL injury and reinjury after surgical reconstruction.

An Increased Lateral Femoral Condyle Ratio Is an Important Risk Factor for a Medial Meniscus Ramp Lesion Including Red-Red Zone Tear

PURPOSE

This study aimed to determine radiological findings associated with ramp lesions in knees with anterior cruciate ligament (ACL) injury.

METHODS

This study included the primary ACL reconstructions from June 2011 to March 2019. The exclusion criteria were combined fractures and multiligament injuries. Patients were categorized based on arthroscopy-confirmed presence of ramp lesions, which was defined as a longitudinal tear around the meniscocapsular junction or red-red zone tear of medial meniscus posterior horn. Binary logistic regression analysis was performed to find the risk factors such as age, sex, body mass index, medial tibial slope, mechanical axis angle, presence of Segond fracture, and lateral femoral condyle (LFC) ratio. Additionally, receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) were evaluated.

RESULTS

Ramp lesions were identified in 89 (27.7%) patients among the total 321 included primary ACL reconstructions. The risk of ramp lesion was associated with increased LFC ratio (odds ratio [OR]: 62.929; 95% confidence interval [CI]: 8.473-467.351; P < .001), varus alignment >3° (OR: 5.858; 95% CI: 3.272-10.486; P < .001), and steeper medial tibial slope (OR: 1.183; 95% CI: 1.05-1.333; P = .006). The cutoff values of the LFC ratio and medial tibial slope for ramp lesions were >71% (AUC: 0.696; sensitivity: 43.82%; specificity: 91.38%; P < .001) and >12.1° (AUC: 0.643; sensitivity: 85.39%; specificity: 38.79%; P < .001), respectively.

CONCLUSION

Deep posterior LFC, varus alignment, and steep medial tibial slope were associated factors for ramp lesions in knees with ACL injury. In patients with ACL injury who show the above-mentioned radiographic findings, careful assessment and suspicion for ramp lesions should be considered.

STUDY DESIGN

Level III, retrospective cross-sectional study.

Analysis of copy number variation in dogs implicates genomic structural variation in the development of anterior cruciate ligament rupture

Anterior cruciate ligament (ACL) rupture is an important condition of the human knee. Second ruptures are common and societal costs are substantial. Canine cranial cruciate ligament (CCL) rupture closely models the human disease. CCL rupture is common in the Labrador Retriever (5.79% prevalence), ~100-fold more prevalent than in humans. Labrador Retriever CCL rupture is a polygenic complex disease, based on genome-wide association study (GWAS) of single nucleotide polymorphism (SNP) markers. Dissection of genetic variation in complex traits can be enhanced by studying structural variation, including copy number variants (CNVs). Dogs are an ideal model for CNV research because of reduced genetic variability within breeds and extensive phenotypic diversity across breeds. We studied the genetic etiology of CCL rupture by association analysis of CNV regions (CNVRs) using 110 case and 164 control Labrador Retrievers. CNVs were called from SNPs using three different programs (PennCNV, CNVPartition, and QuantiSNP). After quality control, CNV calls were combined to create CNVRs using ParseCNV and an association analysis was performed. We found no strong effect CNVRs but found 46 small effect (max(T) permutation P<0.05) CCL rupture associated CNVRs in 22 autosomes; 25 were deletions and 21 were duplications. Of the 46 CCL rupture associated CNVRs, we identified 39 unique regions. Thirty four were identified by a single calling algorithm, 3 were identified by two calling algorithms, and 2 were identified by all three algorithms. For 42 of the associated CNVRs, frequency in the population was <10% while 4 occurred at a frequency in the population ranging from 10–25%. Average CNVR length was 198,872bp and CNVRs covered 0.11 to 0.15% of the genome. All CNVRs were associated with case status. CNVRs did not overlap previous canine CCL rupture risk loci identified by GWAS. Associated CNVRs contained 152 annotated genes; 12 CNVRs did not have genes mapped to CanFam3.1. Using pathway analysis, a cluster of 19 homeobox domain transcript regulator genes was associated with CCL rupture (P = 6.6E-13). This gene cluster influences cranial-caudal body pattern formation during embryonic limb development. Clustered genes were found in 3 CNVRs on chromosome 14 (HoxA), 28 (NKX6-2), and 36 (HoxD). When analysis was limited to deletion CNVRs, the association was strengthened (P = 8.7E-16). This study suggests a component of the polygenic risk of CCL rupture in Labrador Retrievers is associated with small effect CNVs and may include aspects of stifle morphology regulated by homeobox domain transcript regulator genes.

A decreased ratio of height of lateral femoral condyle to anteroposterior diameter is a risk factor for anterior cruciate ligament rupture

Background

Studies have shown that the spherical shape of the lateral femoral condyle has a clear relationship with the relative axial movement of tibiofemoral joint and the anterior cruciate ligament (ACL) rupture. The purpose of this study was to describe the distal curvature of the lateral femoral condyle by ratio of height of lateral femoral condyle to anteroposterior diameter (HAPR), and evaluate its correlation with ACL rupture.

Methods

A retrospective case-control study of 64 patients was conducted. Two age-and sex-matched cohorts (each n = 32) were analyzed: primary ACL ruptures, and a control group consisting of isolated meniscal tears. On the radiograph, the distance from the intersection of the axis of the distal femur and the anteriorly diameter of the lateral femoral condyle to the lower point of the lateral femoral condyle divided by the anteriorly diameter of the lateral femoral condyle is HAPR. The HAPR was measured by digital radiograph imaging systems (DR) to quantify femoral sphericity. Cutoff values were defined; and diagnostic performance of the risk factors was assessed. Meanwhile, we measured the posterior tibial slope (PTS) on radiograph and compared the two methods to evaluate the significance of HAPR in predicting ACL rupture.

Results

A total of sixty-four patients who met the inclusion criteria were included in the final analysis (32 with primary ACL rupture, 32 controls). The HAPR was smaller in the knees with primary ACL rupture (0.31 ± 0.02) than that of the control group (0.33 ± 0.02) (p < 0.01). The PTS was bigger in the knees with primary ACL rupture (8.18 ± 2.77) than that of the control group (6.61 ± 2.85) (p = 0.036). The AUC of HAPR was bigger (0.825; 95% CI, 0.72–0.93) than that of PTS (0.675; 95%CI, 0.85–0.81). The calculated cutoff of HAPR of 0.32 (Youden index, 0.56) was associated with an increased risk for ACL rupture, with sensitivity of 75% and specificity of 81% to predict an ACL rupture.

Conclusions

This study showed that a decreased HAPR is associated with an ACL rupture, and the decrease of HAPR was more significant in predicting ACL ruptures than the PTS. This helps clinicians identify susceptible individuals who may benefit from targeted ACL rupture prevention counseling and intervention.

Introducing the Lateral Femoral Condyle Index as a Risk Factor for Anterior Cruciate Ligament Injury

BACKGROUND

The asymmetry of the medial and lateral knee compartments contributes significantly to femorotibial biomechanics and pivoting, and it is reported to be a relevant risk factor for an anterior cruciate ligament (ACL) injury.

PURPOSE

(1) To assess the role of femoral condyle sphericity as a risk factor for an ACL rupture and rerupture. (2) To compare the new risk factor with existing bony morphological risk factors via magnetic resonance imaging (MRI) and to assess the most predictive risk factor for an ACL rupture.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective case-control study of 60 patients was conducted. Three age- and sex-matched cohorts (each n = 20) were analyzed: ACL reruptures, primary ACL ruptures, and a control group consisting of isolated meniscal tears or patients with anterior knee pain without signs of trochlear dysplasia. The lateral femoral condyle index (LFCI) as a novel MRI measurement was developed to quantify femoral sphericity. In addition, previously known MRI risk factors associated with ACL injury were analyzed (notch width index, medial tibial slope, lateral tibial slope, medial tibial depth, and lateral tibial height). Differences among groups were compared; cutoff values were defined; and diagnostic performance of the risk factors was assessed. The risk factors were subsequently analyzed with multiple logistic regression.

RESULTS

The LFCI was significantly smaller in knees with ACL reruptures (median, 0.67; range, 0.59-0.75) and primary ACL ruptures (0.67; range, 0.60-0.75) than in the control group (0.76; range, 0.6-0.81; P < .01). The LFCI yielded the highest area under the curve among the analyzed risk factors: 0.82 (95% CI, 0.7-0.9). A cutoff of 0.70 yielded a sensitivity of 78% and a specificity of 80% to predict an ACL rupture or rerupture (odds ratio, 13.79; 95% CI, 3.67-51.75). In combination with lateral tibial height (cutoff, 3.8 mm) and lateral tibial slope (cutoff, 2.9°), the diagnostic performance was improved. The area under the curve was 0.86 (95% CI, 0.75-0.94), with a sensitivity of 90% and a specificity of 70% (odds ratio, 21.00; 95% CI, 5.10-85.80).

CONCLUSION

A decreased LFCI is associated with an ACL injury. The LFCI, lateral tibial height, and lateral tibial slope are the most predictive risk factors for an ACL injury. These findings might aid clinicians in identifying patients at risk for an ACL injury and inform the patient after reconstruction for a higher risk of rerupture.

Patients With Failed Anterior Cruciate Ligament Reconstruction Have an Increased Posterior Lateral Tibial Plateau Slope: A Case-Controlled Study

PURPOSE

To compare knee anatomical parameters of patients with failed anterior cruciate ligament reconstruction (ACL-R) with those of a control group of sex-matched patients with successful ACL-R.

METHODS

Forty-three patients (34 male, 9 female) who experienced graft failure after ACL-R were enrolled in the failed group. These patients were matched to a control group of 43 patients who underwent primary ACL-R with a minimum follow-up of 24 months. On magnetic resonance imaging, the following parameters were evaluated: transepicondylar distance, lateral and medial femoral condyle widths, tibial plateau width, notch width index, and the ratio of width and height of the femoral notch, ratio between the height and depth of the lateral and medial femoral condyle, lateral and medial posterior tibial slopes, and anterior subluxation of the lateral and medial tibial plateau. Multivariate regression with backward elimination, including only the previously identified significant variables, defined the independent predictors for revision surgery.

RESULTS

The anatomical variables that were significantly different between the 2 study groups were lateral and medial posterior tibial slopes, anterior subluxation of the lateral and medial tibial plateau, medial tibial plateau width, lateral tibial plateau width, medial femoral condyle width, and transepicondylar distance; however, the multivariate regression analysis identified the lateral posterior tibial slope (LTPs), the anterior subluxation of the medial tibial plateau, and the medial femoral condyle width as significant independent predictors (P < .05). The LPTs had the highest coefficient and the highest sensitivity (88%) and specificity (84%) to identify failures when considering the optimal cutoff value of 7.4°.

CONCLUSIONS

Several anatomical parameters have been identified that differ significantly between patients with failed ACL-R and those without a documented failure. The most accurate predictor of ACL failure was an LTPs >7.4°, with a sensitivity of 88% and specificity of 84%. Surgeons should consider measuring LTPs during preoperative assessment of ACL-injured patients, and patients with values >7.4° should be considered at high risk of ACL-R failure.

LEVEL OF EVIDENCE

Level III retrospective prognostic trial.

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.

Top orthopedic sports medicine procedures

Orthopedic sports medicine is a subspecialty of Orthopedics that focuses on managing pathological conditions of the musculoskeletal system arising from sports practice. When dealing with athletes, timing is the most difficult issue to face. Typically, athletes aim to return to play as soon as possible and at the pre-injury level. This means that management should be optimized to combine the need for prompt return to sport and to the biologic healing time of the musculo-skeletal. This poses a great challenge to sport medicine surgeons, who need to follow with attention to the latest scientific evidence to offer their patients the best available treatment options. We briefly review the most commonly performed orthopedic sports medicine procedures, outlining the presently available scientific evidence on their indications and outcomes.

Clinical Management in Early OA

Knee osteoarthritis affects an important percentage of the population throughout their life. Several factors seem to be related to the development of knee osteoarthritis including genetic predisposition, gender, age, meniscal deficiency, lower limb malalignments, joint instability, cartilage defects, and increasing sports participation. The latter has contributed to a higher prevalence of early onset of knee osteoarthritis at younger ages with this active population demanding more consistent and durable outcomes. The diagnosis is complex and the common signs and symptoms are often cloaked at these early stages. Classification systems have been developed and are based on the presence of knee pain and radiographic findings coupled with magnetic resonance or arthroscopic evidence of early joint degeneration. Nonsurgical treatment is often the first-line option and is mainly based on daily life adaptations, weight loss, and exercise, with pharmacological agents having only a symptomatic role. Surgical treatment shows positive results in relieving the joint symptomatology, increasing the knee function and delaying the development to further degenerative stages. Biologic therapies are an emerging field showing early promising results; however, further high-level research is required.