Sensitivity and specificity of bell-hammer tear as an indirect sign of partial anterior cruciate ligament rupture on magnetic resonance imaging

The potential of posterior cruciate ligament buckling phenomenon as a sign for partial anterior cruciate ligament tears

INTRODUCTION

Diagnosis of a partial tear of the anterior cruciate ligament (ACL) can be challenging with physical examination and imaging techniques. Although magnetic resonance imaging (MRI) has high sensitivity and specificity for diagnosing complete ACL tears, its effectiveness may be limited when it is used to diagnose for partial tears. The hypothesis of the present study is that the posterior cruciate ligament (PCL) buckling phenomenon, which is a secondary sign of complete ACL tears on MRI, may be a useful method for diagnosing partial ACL tears.

MATERIALS AND METHODS

The data of 239 patients who underwent knee arthroscopy in a single institution between 2016 and 2022 were analyzed retrospectively. Patients were divided into three groups based on the condition of their ligaments: partial tears, complete tears and intact ligaments. To evaluate the buckling phenomenon on sagittal T2-weighted MRI, measurements of the posterior cruciate ligament angle (PCLA) and the posterior cruciate ligament-posterior cortex angle (PCL-PCA) were conducted in each group. Subsequently, the ability of these two measurement methods to distinguish partial tears from the other groups was assessed.

RESULTS

Both methods provided significantly different results in all three groups. Partial tears could be distinguished from intact ligaments with 86.8% sensitivity, 89.9% specificity when PCLA < 123.13° and 94.5% sensitivity, 93.2% specificity when PCL-PCA < 23.77°. Partial tears could be distinguished from complete tears with 79.5% sensitivity, 78.4% specificity when PCLA > 113.88° and with 86.1% sensitivity, 85.3% specificity when PCL-PCA > 16.39°.

CONCLUSION

The main finding of the present study is that the PCLA and PCL-PCA methods are useful on MRI for diagnosing partial ACL tears. PCLA value between 113°-123° and PCL-PCA value between 16°-24° could indicate a partial ACL tear. With these methods, it is possible to distinguish partial tears from healthy knees and reduce missed diagnoses. In addition, the differentiation of partial and complete tears by these methods may prevent unnecessary surgical interventions.

LEVEL OF EVIDENCE

Level III.

MRI findings of acute anterior instability of the knee in the absence of recent trauma

BACKGROUND

Anterior knee instability is usually encountered in the context of trauma, with the clinical examination and imaging focusing on anterior cruciate ligament (ACL) disruption. Limited data exist on magnetic resonance imaging (MRI) of acute anterior knee instability in the absence of recent trauma.

PURPOSE

To provide the first comprehensive account of MRI findings in acute anterior knee laxity in the absence of acute trauma and to evaluate predictors of ACL integrity and pain.

MATERIAL AND METHODS

A total of 84 consecutive patients with non-traumatic knee instability were prospectively studied. Instability was assessed with Lachman's, pivot shift, and Lelli's tests. MRI findings were recorded, and ACL integrity was surgically confirmed in all 24 cases of MRI suggesting tear and in 21/60 cases of MRI suggesting no tear. Binary logistic regression models were used to identify predictors of ACL tears and pain, and Mann-Whitney U test served for comparisons between continuous variables. The study was approved by the institutional review board.

RESULTS

Osteoarthritis and notch bony outgrowth (NBO) were present in 44% and 42.9% of all knees, respectively. NBO did not correlate with osteoarthritis (P = 0.606). NBO (odds ratio [OR] = 4.157; P = 0.016) and ACL grafts (OR = 9.277; P = 0.01) predisposed to non-traumatic ACL tears (torn in 28.6% of total cases). Presence of osteoarthritis was predictive of pain (OR = 17.671; P < 0.001).

CONCLUSION

We present a comprehensive analysis of MRI findings in clinically significant non-traumatic anterior instability, showing that NBO and ACL grafts predispose in non-traumatic ACL tears, whereas osteoarthritis is the only predictor of pain.

A modified anterior drawer test for anterior cruciate ligament ruptures

Objective

This study was aimed to utilize a modified anterior drawer test (MADT) to detect the anterior cruciate ligament (ACL) ruptures and investigate its accuracy compares with three traditional tests.

Methods

Four hundred patients were prospectively enrolled between January 2015 and September 2017 preoperatively to undergo knee arthroscopic surgeries. The MADT, anterior drawer test, Lachman test, and pivot shift test were used in the outpatient clinical setting and were compared statistically for their accuracy in terms of ACL ruptures, with arthroscopic findings as the gold standard.

Results

The prevalence of ACL ruptures in this study was 37.0%. The MADT demonstrated the highest sensitivity (0.89) and accuracy (0.92) among the four tests and had comparable specificity (0.94) and a positive predictive value (0.90) compared with the anterior drawer test, Lachman test, and pivot shift test. The diagnostic odds ratio (DOR) of MADT was 122.92, with other test values of no more than 55.45. The area under the receiver operating characteristic curve (AUC) for the MADT was 0.92 ± 0.01, with a significant difference compared with that for the anterior drawer test (z = 17.00, p < 0.001), Lachman test (z = 9.66, p = 0.002), and pivot shift test (z = 16.39, p < 0.001). The interobserver reproducibility of the MADT was good, with a kappa coefficient of 0.86.

When diagnosing partial tears of ACL, the MADT was significantly more sensitive than the anterior drawer test (p < 0.001), Lachman test (p = 0.026), and pivot shift test (p = 0.013). The MADT showed similar sensitivity in detecting anteromedial and posterolateral bundle tears (p = 0.113) and no difference in diagnosing acute and chronic ACL ruptures (χ² = 1.682, p = 0.195).

Conclusions

The MADT is also an alternative diagnostic test to detect ACL tear, which is equally superior to the anterior drawer test, Lachman test, and pivot shifting test. It could improve the diagnosis of ACL ruptures combined with other clinical information including injury history, clinical examination, and radiological findings.

Levels of evidence

Level II/observational diagnostic studies

Trial registration

Chinese Clinical Trial Registry. ChiCTR1900022945 /retrospectively registered

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02381-x.

Is a Partial Anterior Cruciate Ligament Tear Truly Partial? A Clinical, Arthroscopic, and Histologic Investigation

PURPOSE

(1) To determine whether examination under anesthesia (EUA) and/or magnetic resonance imaging (MRI) is an accurate means for determining patient selection for a selective-bundle reconstruction, (2) to determine whether the preoperative clinical assessment correlates with the arthroscopic examination, and (3) to examine histologically whether a partial anterior cruciate ligament (ACL) tear is truly partial in terms of vascular insult.

METHODS

This prospective, nonrandomized cohort study included 95 patients who underwent primary ACL reconstruction from January 2013 through May 2014. All patients underwent an EUA, MRI, and arthroscopic evaluation. In patients with partial ACL tears, the intact bundle was resected and underwent histologic examination. The χ² test was used to compare EUA and MRI in the detection of partial tears.

RESULTS

Of the 95 patients included, 40 (42%) had EUA findings consistent with a partial ACL tear whereas 22 (23%) had MRI findings interpreted as showing a partial ACL tear. Arthroscopic examination confirmed a partial ACL tear in only 11 patients (12%). The sensitivity of EUA and MRI in the detection of partial ACL tears was 100% and 90.9%, and the specificity was 65% and 85.7%, respectively. The χ² test suggested statistically significant associations between the method of evaluation and diagnostic outcome [χ²(1) = 7.83, P = .005]. MRI was 1.24 times more likely to correctly identify a partial tear (95% confidence interval, 1.06-1.45). EUA was 2.23 times as likely to incorrectly identify a partial tear (95% confidence interval, 1.24-4.02). The histologic analysis showed increased numbers of lymphocytes, absent polymorphonuclear leukocytes, predominant fibroblasts, neovascularization, and variable collagen orientation.

CONCLUSIONS

There is a disparity between EUA, MRI, and arthroscopic findings in the evaluation of partial ACL tears. Arthroscopy remains the gold standard for diagnosing the macroscopic integrity of the intact bundle. Microscopic analysis reveals that the integrity of the remaining intact ligament material is altered and may show a histologic response similar to a complete ACL rupture.

LEVEL OF EVIDENCE

Level III, prospective, nonrandomized cohort study.

Knee Extension Deficit in the Early Postoperative Period Predisposes to Cyclops Syndrome After Anterior Cruciate Ligament Reconstruction: A Risk Factor Analysis in 3633 Patients From the SANTI Study Group Database

BACKGROUND

Cyclops syndrome is characterized by a symptomatic extension deficit attributed to impingement of a cyclops lesion within the intercondylar notch. The syndrome is an important cause of reoperation after anterior cruciate ligament reconstruction (ACLR). It has been suggested that remnant-preserving ACLR techniques may predispose to cyclops syndrome, but there is very limited evidence to support this. In general terms, risk factors for cyclops syndrome are not well-understood.

PURPOSE

To determine the frequency of and risk factors for reoperation for cyclops syndrome in a large series of patients after ACLR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A retrospective analysis of prospectively collected data was performed, including all patients who underwent primary ACLR between January 2011 to December 2017. Patients undergoing major concomitant procedures were excluded. Demographic data, intraoperative findings (including the size of preserved remnants), and postoperative outcomes were recorded. Those patients who underwent reoperation for cyclops syndrome were identified, and potential risk factors were evaluated in multivariate analysis.

RESULTS

A total of 3633 patients were included in the study, among whom 65 (1.8%) underwent reoperation for cyclops syndrome. Multivariate analysis demonstrated that preservation of large remnants did not predispose to cyclops lesions (odds ratio [OR], 1.11; 95% CI, 0.63-1.93). The most important risk factor was extension deficit in the early postoperative period. If present at 3 weeks postoperatively, it was associated with a >2-fold increased risk of cyclops syndrome (OR, 2.302; 95% CI, 1.268-4.239; P < .01), which was increased to 8-fold if present 6 weeks after ACLR (OR, 7.959; 95% CI, 4.442-14.405; P < .0001). None of the other potential risk factors evaluated were found to be significantly associated with an increased frequency of cyclops syndrome.

CONCLUSION

Failure to regain full extension in the early postoperative period was the only significant risk factor for cyclops syndrome after ACLR in a large cohort of patients. Other previously hypothesized risk factors, such as preservation of a large anterior cruciate ligament remnant, did not predispose to the development of this debilitating postoperative complication.

Increased ATFL-PTFL angle could be an indirect MRI sign in diagnosis of chronic ATFL injury

PURPOSE

Magnetic resonance imaging (MRI) has relatively low accuracy in diagnosing chronic anterior talofibular ligament (ATFL) injury. This study's purpose was to evaluate the angle between the ATFL and posterior talofibular ligament (PTFL) as a new indirect MRI sign of chronic ATFL injury in patients with mechanical ankle instability (MAI).

METHODS

This study included 200 participants: 105 patients with MAI and 95 patients seen at our institution for reasons unrelated to ankle instability. MR images of all 200 participants were reviewed. The ATFL-PTFL angle in the axial plane was measured and compared between groups. Receiver operating characteristic curves (ROC) were used to analyze ATFL-PTFL angles in participants with and without ATFL injury. The sensitivity and specificity of this method for diagnosing ATFL injury were calculated.

RESULTS

The mean ATFL-PTFL angle was significantly larger among MAI patients than among control patients (81.5° ± 9.8° vs 75.2° ± 8.9°, respectively; P < 0.01). The area under the ROC was 0.789 (P < 0.01). The optimal cut-off point for diagnosing ATFL injury on the basis of the ATFL-PTFL angle was 79.0° (sensitivity 0.89, specificity 0.67).

CONCLUSION

The ATFL-PTFL angle was significantly larger among MAI patients than among those without MAI. Increased ATFL-PTFL angle offers a new indirect MRI sign for diagnosing chronic ATFL injury. The ATFL-PTFL angle can be used not only to improve the accuracy of diagnosis of chronic ATFL injury, but also to evaluate the restoration of normal ankle joint geometry after lateral ligament reconstruction.

LEVEL OF EVIDENCE

III.

Imaging of Athletic Injuries of Knee Ligaments and Menisci: Sports Imaging Series

Acute knee injuries are a common source of morbidity in athletes and if overlooked may result in chronic functional impairment. Magnetic resonance (MR) imaging of the knee has become the most commonly performed musculoskeletal MR examination and is an indispensable tool in the appropriate management of the injured athlete. Meniscal and ligamentous tearing are the most frequent indications for surgical intervention in sports injuries and an understanding of the anatomy, biomechanics, mechanisms of injury, and patterns of injury are all critical to accurate diagnosis and appropriate management. These will be discussed in reference to meniscal tears and injuries of the cruciate ligaments as well as injuries of the posterolateral and posteromedial corners of the knee. (©) RSNA, 2016.

Clinical outcomes and biomechanical analysis of posterolateral bundle augmentation in patients with partial anterior cruciate ligament tears

PURPOSE

To examine the clinical and biomechanical results of posterolateral (PL) augmentation to reconstruct damaged PL bundle while preserving the less-damaged anteromedial bundle for partial anterior cruciate ligament (ACL) tears in comparison with double-bundle ACL reconstruction.

METHODS

Sixteen patients who underwent PL augmentation for partial ACL tears (Group P) and 37 patients who underwent double-bundle ACL reconstructions for complete ACL tears were examined (Group D). Anterior tibial translation (ATT) was evaluated using the KT-1000 arthrometer. ATT during the Lachman test and acceleration of posterior tibial translation (APT) during the pivot shift test were evaluated using an electromagnetic measurement system (EMS). Clinical outcomes were evaluated using the Lysholm score. Second-look arthroscopy was performed 1 year after surgery.

RESULTS

The mean postoperative Lysholm scores were 91.7 ± 12.2 and 94.6 ± 7.2 in Groups P and D, respectively, and there was no statistically significant difference between the two groups. The mean side-to-side difference of ATT on the KT-1000 was significantly improved in both Groups P and D. In the EMS analysis, the mean side-to-side difference of ATT and the mean APT were significantly improved in both Groups P and D. There was no significant difference in the second-look evaluation between the two groups.

CONCLUSIONS

The clinical and biomechanical outcomes of PL augmentation were satisfactorily comparable to those of double-bundle ACL reconstruction. PL augmentation could be a useful treatment option for patients with partial ACL tears.

LEVEL OF EVIDENCE

IV.

How sensitive and specific is 1.5 Tesla MRI for diagnosing injuries in patients with knee dislocation?

PURPOSE

The purpose of this study was to assess the sensitivity and specificity of 1.5 T magnetic resonance imaging (MRI) in diagnosing and identifying the specific injury pattern in patients with knee dislocation. The hypothesis was that the sensitivity and specificity are low in patients with posterolateral corner injury and/or PCL tear.

METHODS

A retrospective study was performed on 38 patients (m:f = 29:9, mean age ± SD 34.3 ± 14.0) with traumatic knee dislocation, who underwent 1.5 T MRI prior to surgery. MRI scans were analysed by a musculoskeletal radiologist, and the presence and type of tears to ligaments, tendons and meniscus or bone were recorded. Comparison was made with the intraoperative findings from the surgical records using the same reporting scheme. The agreement between MRI and surgical findings was assessed using kappa statistics, and the sensitivity and specificity were calculated.

RESULTS

In patients with knee dislocation, MRI was found to have low sensitivity (25-38 %) but high specificity (94-97 %) for diagnosing injury to the posterolateral corner. There was high sensitivity in the diagnosis of tears in the cruciate and collateral ligaments (97-100 %); the specificity, however, was lower (50-67 %). The diagnosis of meniscal injury showed low sensitivity (36-56 %) and moderate specificity (69-83 %).

CONCLUSIONS

MRI is a sensitive measure of cruciate and collateral ligament injury in acute knee dislocation; however, it does not reliably diagnose injury to the posterolateral corner or meniscus, and therefore, a higher index of suspicion is required during arthroscopy to prevent misdiagnosis which could affect long-term clinical outcome.

LEVEL OF EVIDENCE

Diagnostic study, Level II.

Hamstring Contracture After ACL Reconstruction Is Associated With an Increased Risk of Cyclops Syndrome

Background:

Cyclops syndrome is characterized by loss of terminal knee extension due to proliferative fibrous nodule formation in the intercondylar notch. This complication occurs in the early postoperative period after anterior cruciate ligament reconstruction (ACLR). The pathogenesis of Cyclops syndrome is not well understood.

Hypothesis:

Persistent hamstring contracture after ACLR is associated with an increased risk of subsequent Cyclops syndrome.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The files of 45 patients who underwent arthroscopic debridement of a Cyclops lesion after ACLR were analyzed. Recorded data included demographic information and technical details of surgery. Preoperative magnetic resonance images were also analyzed, and patients with femoral bone bruising were identified. Passive and active range of motion were recorded in all patients preoperatively and at 3 and 6 weeks after surgery to address the Cyclops lesion. Passive extension deficit was evaluated in comparison with the contralateral limb and classified as secondary to hamstring contracture when contracture was observed and palpated in the prone position and when the extension deficit was reversed after exercises performed to fatigue the hamstrings. A control group was selected using a random numbers table among our entire ACLR cohort. Statistical analysis was performed to analyze differences between the 2 groups.

Results:

There was no significant difference between the groups with regard to age at ACLR, sex distribution, time from injury to surgery (P > .05), proportion of professional athletes, presence of femoral bone bruise, or technical aspects of surgery. The overall extension deficit incidence was significantly higher in the Cyclops group at 3 weeks (Cyclops, 71%; control, 22%) (P < .001) and at 6 weeks (Cyclops, 60%; control, 7%) (P < .001). The extension deficit related to hamstring contracture was significantly higher in the Cyclops group at 3 weeks (Cyclops, 58%; control, 22%) (P < .001) and at 6 weeks (Cyclops, 29%; control, 2%) (P < .001).

Conclusion:

The Cyclops lesion is associated with a persistent hamstring contracture at 3 and 6 weeks after ACLR.

The "Lever Sign": a new clinical test for the diagnosis of anterior cruciate ligament rupture

PURPOSE

A new clinical test for the diagnosis of ACL rupture is described: the so-called "Lever Sign". This prospective study on four groups of patients divided subjects on the basis of MRI findings (complete or partial ACL lesion) and the clinical phase of the injury (acute or chronic). The hypothesis was that this manual test would be diagnostic for both partial and complete tears of the ACL regardless of the elapsed time from injury.

METHODS

A total of 400 patients were evaluated and divided into four, equal-sized groups based on time elapsed from injury and MRI findings: Group A (acute phase with positive MRI for complete ACL rupture), Group B (chronic phase with positive MRI for complete ACL rupture), Group C (acute phase with positive MRI for partial ACL rupture), and Group D (chronic phase with positive MRI for partial ACL rupture). Clinical assessment was performed with the Lachman test, the Anterior Drawer test, the Pivot Shift test, and the Lever Sign test. The Lever Sign test involves placing a fulcrum under the supine patient's calf and applying a downward force to the quadriceps. Depending on whether the ACL is intact or not, the patient's heel will either rise off of the examination table or remain down. Additionally, the Lever Sign test was performed on the un-injured leg of all 400 patients as a control.

RESULTS

All tests were nearly 100 % sensitive for patients with chronic, complete tears of the ACL. However, for patients with acute, partial tears, the sensitivity was much lower for the Lachman test (0.42), Anterior Drawer test (0.29), and Pivot Shift test (0.11), but not the Lever Sign test (1.00).

CONCLUSION

In general, chronic, complete tears were most successfully diagnosed but acute, partial tears were least successfully diagnosed. The Lever Sign test is more sensitive to correctly diagnosing both acute and partial tears of the ACL compared with other common manual tests. The clinical relevance is that some ACL ruptures may be more accurately diagnosed.

The arthroscopical and radiological corelation of lever sign test for the diagnosis of anterior cruciate ligament rupture

The aim of the current study was to evaluate the sensitivity of the lever sign test and the widely used basic tests of the Lachman, anterior drawer and pivot shift tests, both under anaesthesia and without anaesthesia, according to the gold standard diagnostic arthroscopic results in patients undergoing anterior cruciate ligament reconstruction. The study included 117 patients, diagnosed with ACL tear which was definitively determined during an arthroscopic surgical procedure applied. Before anaesthesia and while under anaesthesia, the Lachman, anterior drawer, pivot shift and lever sign tests were applied to all patients. Evaluation was made of MR images for each patient and documented. The patients comprised 96 males and 21 females, witha mean age of 25.8 ± 5.9 years (range, 17-45 years). Total tear was determined in 82 cases, anteromedial (AM) bundle in 14, posterolateral (PL) bundle in 13 and elongation in 8. Pre-anaesthesia positivity was found in lever sign at 94.2 %, Lachman at 80.5 %, pivot shift at 62.3 % and anterior drawer at 60.1 %. These rates were determined after anaesthesia as lever sign 98.4 %, Lachman 88.7 %, pivot shift 88.3 % and anterior drawer 84.2 %. The lever sign test can be easily applied clinically and it seems to have higher sensitivity than the Lachman test which is the basis of classic information, it should be included in routine clinical practice. In the light of the results of this study, further studies are required to review the accepted view that the Lachmann test is the most reliable test.

Functional imaging in OA: role of imaging in the evaluation of tissue biomechanics

Functional imaging refers broadly to the visualization of organ or tissue physiology using medical image modalities. In load-bearing tissues of the body, including articular cartilage lining the bony ends of joints, changes in strain, stress, and material properties occur in osteoarthritis (OA), providing an opportunity to probe tissue function through the progression of the disease. Here, biomechanical measures in cartilage and related joint tissues are discussed as key imaging biomarkers in the evaluation of OA. Emphasis will be placed on the (1) potential of radiography, ultrasound, and magnetic resonance imaging to assess early tissue pathomechanics in OA, (2) relative utility of kinematic, structural, morphological, and biomechanical measures as functional imaging biomarkers, and (3) improved diagnostic specificity through the combination of multiple imaging biomarkers with unique contrasts, including elastography and quantitative assessments of tissue biochemistry. In comparison to other modalities, magnetic resonance imaging provides an extensive range of functional measures at the tissue level, with conventional and emerging techniques available to potentially to assess the spectrum of preclinical to advance OA.