The Validation of Clinical Examination and MRI as a Diagnostic Tool for Cruciate Ligaments and Meniscus Injuries of the Knee Against Diagnostic Arthroscopy

Background: This study was conducted to compare the accuracy of MRI findings and clinical examination of ligamentous and meniscal injuries of the knee, taking arthroscopy as a standard diagnostic tool in knee injuries. Methods: All patients with knee injuries attending the outpatient department or emergency of our hospital underwent clinical examination. Out of them, 60 patients with knee injuries were subjected to clinical examination, MRI, and then arthroscopy. The findings of these diagnostic tools in respect to the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and meniscus injuries were validated, compared, and analyzed using various statistical tools. The accuracy, sensitivity, negative predictive value (NPV), positive predictive value (PPV), and specificity were calculated and an agreement between various tests was established using kappa statistics. Results: The accuracy of clinical examination in our study was 88% for ACL tears, 85% for meniscal tears, and 100% for PCL tears. The kappa measure of agreement between arthroscopy and clinical finding and MRI for ACL was 0.610 and 0.698, respectively, which was statistically significant. MRI (98.1) was found to be a more sensitive test for detecting ACL injury than clinical examination (90.4%) resulting in higher diagnostic accuracy (98.3%), while diagnostic accuracy of clinical examination and MRI was found to be 100% for PCL injuries. Hence, MRI is an excellent screening tool for ligamentous and meniscal injuries of the knee joint. We can avoid diagnostic arthroscopy in patients with knee injuries having equivocal clinical and MRI examinations and can proceed for therapeutic arthroscopy to deal with such injuries. Conclusions: For the assessment of ligamentous and meniscal injuries, MRI is an accurate and noninvasive modality. It can be used as a first-line investigation but arthroscopy remains the gold standard.


Introduction
In today's world of technology and advancement, we often come across ill hazards popping out of it. Road traffic accidents are tremendously increasing in number with increasing incidence of various injuries like ligamentous and meniscal injuries within the knee. Many times, we find patient coming with complaints of knee injury from all age groups, from a pedestrian crossing street to elderly falling on the ground, almost all athletes' experiences knee injury during their lifetimes.
The knee joint has a complex structure due to which it is more susceptible to different types of injuries like fracture, dislocation, and tear in the ligaments, tendons, and cartilage. Because of its physical nature, its vulnerability to external forces, and the functional demands imposed on it, the knee is one of the most commonly injured joints [1].
In older times we had limited resources to diagnose and manage cases associated with a knee injury and it was mainly done based on the clinical examination and x-rays. Clinical examinations are used to diagnose knee injuries, with some of them have become standard clinical tests for particular injuries a long time ago [2].
With the advent of radiological advancements, like MRI and CT scans we can look more clearly inside the joint. Above all, MRI provides the advantage of being a fast, non-invasive, diagnostic tool to look for ligament and menisci injuries. Thus, it minimizes the agony and morbidity faced by the patients, along with the ease in the management with better planning and optimal intervention in time. MRI provides a better understanding to identify the ligament, menisci, synovial injury. MRI diagnosed almost all the ligamentous and meniscus injuries with a great level of confidence [3].
Arthroscopic examination of the knee is a more valuable method than diagnosis by MRI and clinical tests for detecting meniscal-cruciate injuries of the knee [4][5][6]. Arthroscopy has now become the gold standard in diagnosing knee pathologies [5].
The purpose of our study was to validate the findings of clinical examination and MRI as a diagnostic tool for intraarticular knee injuries; anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and meniscal injuries of the knee against findings of diagnostic arthroscopy.

Materials And Methods
This prospective cohort study was conducted on 60 individuals in the Department of Orthopedics, King George's Medical University, Lucknow, Uttar Pradesh, India, who had fulfilled the inclusion criteria and had given consent for the study. The study period was one year from February 2019 to February 2020. The study was approved by the institutional ethics committee.
The study population was having a history of knee injury with suspected anterior cruciate ligament, posterior cruciate ligament, and meniscus injury admitted to the Department of Orthopedics, King George's Medical University. The patients within the age group of 18-45 years having a history of knee injury and suspected traumatic anterior cruciate ligament, posterior cruciate ligament, and menisci injury within eight weeks were included.
The patients with conditions that preclude MRI-like patients having intracerebral aneurysmal clips, cardiac pacemaker, stainless steel implants in bone, patients having symptoms suggestive of tumor of the knee joint structures, patients who underwent arthroscopic examination directly without undergoing MRI scanning, and those who were unfit for anesthesia were excluded from the study.
All patients underwent clinical, MRI, and arthroscopic examinations. The findings of clinical examination and MRI were compared with diagnostic arthroscopy. In all patients, radiological investigations were done after three weeks of injury. MRI used was of 1.5 Tesla scanner and T1-and T2-weighted and proton dense slices on sagittal and coronal planes were obtained. Their MRI films were read by our radiologist to report; the radiologist was unaware of the finding of the clinical examination. The cruciate ligaments were classified as partial disruption or complete ligament injury. MRI grading system for meniscal injuries was used in this study ( Table 1).

Grade Signal
Normal No abnormal signal intensity  Arthroscopy was performed by a single operating surgeon having 15 years of experience in knee arthroscopy and who was unaware of clinical and MRI findings. The findings of arthroscopy were considered as true diagnoses.
To classify the location of meniscal tear arthroscopically, each meniscus was divided into three equal segments: (1) the anterior one-third or anterior horn; (2) the middle one-third or body; (3) posterior onethird or posterior horn.
The results were recorded on Microsoft Excel. The number and percentage for qualitative data and mean + SD for quantitative data. In order to assess the reliability and validity of screening tests, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated. The agreement between various tests was evaluated by kappa statistics. The data were analyzed using Microsoft Excel and IBM-SPSS software version 20 (Armonk, NY: IBM Corp.). The p-value less than 0.05 was taken as significant.

Results
In a total of 60 cases, those who had fulfilled inclusion criteria for traumatic cruciate ligaments and meniscal injuries were clinically examined and reviewed with MRI followed by diagnostic arthroscopy and repair/reconstruction. The data were analyzed to calculate true positive, true negative, false positive, and false negatives. Using this, specificity and sensitivity, positive and negative predictive values were calculated with arthroscopic examination as the gold standard for comparison.
Among the enrolled patients, the majority were males, 55 (91.7%), and the rest were females, five (8.3%). The maximum number of patients, 29 (48.3%), were aged between 26 years and 35 years. The mean age of the patients was 29.17±7.98 years. Among the enrolled patients, a maximum of 32 (53.3%) was the victim of road traffic accidents followed by a sports injury and slip-on ground each with 11 (18.3%) cases while 6 (10.0%) cases were of the fall from height.   Both clinical and MRI findings found PCL injury to be positive in eight (13.3%) cases and it corresponds to the arthroscopic findings (  The kappa measure of agreement between arthroscopy and clinical finding for PCL was perfect, 1.00. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy of clinical diagnosis were all 100% (   The clinical and arthroscopy diagnosis for medial meniscus matched positive for nine (15.0%) cases while it was matched positive for 17 (28.33%) with MRI findings. Ten (16.67%) cases were clinically negative but found positive in arthroscopy while one case was clinically positive and negative in arthroscopy ( Table 7). High numbers of false-positive meniscal injury were detected with MRI which can be attributed to the fact that signal of T2-weighted images detects mostly superficial surfaces of menisci.   The lateral meniscus was found to be positive clinically in five (8.3%) cases, MRI found in 10 (16.7%) cases, while arthroscopically, it was detected in eight (13.3%) cases ( Table 9).

TABLE 9: The lateral meniscus injury result summary
The clinical and arthroscopy diagnosis for lateral meniscus matched positive for four (6.67%) cases and matched negative for 51 (85.0%) cases. Further, four (6.67%) cases were positive in arthroscopic findings but clinically negative while one case was negative in arthroscopy but clinically positive (

Discussion
The proper history taking and clinical examination are needed for effective clinical decision-making, which further determines whether the patient needs more investigations or therapeutic intervention, which is beneficial for patients ergonomically as well as the time of his morbidity.
In the past, the clinical examination had a significant role in the diagnosis of knee joint injuries, but with the invention of MRI and because of very few side effects, non-invasiveness and progressive growth in technology made it an important tool of diagnosis.
Among 60 patients, 55 were males and five were females of 18-45 years age group having clinically suspected traumatic ligamentous and meniscal injuries, we found that it was more common in males of 26-35 years age group. A study by Avcu et al. found that knee injuries were common in the male population due to their active participation in outdoor works and sports activities [7]. In our study right knee is more involved than the left knee due to the dominating side in most sportspersons.
We found that sensitivity, specificity, PPV, NPV, and accuracy of clinical examinations performed concerning arthroscopy for an ACL tear is 90.4%, 75.0%, 95.9%, 54.5%, and 83.3%, respectively. A study performed by Panigrahi et al. found that the sensitivity, specificity, PPV, NPV, and accuracy of clinical tests were 94.7%, 71.4%, 90.0%, 83.3%, and 88.5%, respectively [2]. The negative predictive value in our study is less due to the five false-negative cases which were not found during a clinical examination. Out of five patients, two were of chronic anterior cruciate ligament tear; when viewed arthroscopically, we found the stump fibrosis of torn anterior cruciate ligament fibers and its attachment with posterior cruciate ligament which result in negative clinical tests; three patients were of partial anterior cruciate ligament tear on arthroscopy which was also negative on clinical examination. Two patients were positive on clinical examination but arthroscopically normal ACL was found in them. These patients were of 44 years and 45 years of age having a history of trauma presented with knee pain, but on arthroscopy, all ligaments and menisci were normal with some early arthritic changes. A study done by Madhusudhan et al. found that knee with degenerative changes can give false-positive results on clinical examination [8].
For the posterior cruciate ligament injury, we did the clinical examination on the same patients and found that only eight out of 60 patients were of suspected PCL injury clinically. All of the eight patients when undergone MRI, every patient had been detected with PCL injury which was further confirmed on arthroscopy. In our study, we found the sensitivity, specificity, PPV, NPV, and diagnostic accuracy of diagnosing the PCL injury on clinical examination and MRI was 100% for each. A study performed by Gimhavanekar [11]. Previous studies showed these values ranges as for sensitivity 41-100% [2,3,11,14,15], specificity 72-100% [2,10,11,14,15], PPV 34-100% [2,14], NPV 90-100% [2,14], and accuracy 68-100% [2,3,11,14,16]. Our results of MRI for diagnosing the lateral meniscus injuries were as per the findings of the literature.

Conclusions
The accuracy of MRI in the diagnosis of ACL, PCL, and meniscus injuries is exceedingly good. Besides being a noninvasive screening modality, it provides detailed insight and is an essential tool in decision-making before planning for any therapeutic intervention. For the better implications of these results, further studies are warranted with a focus on including using larger sample quantities and multi-centric study.

Additional Information
Disclosures