The medial and lateral condyles of the femur, the tibial plateau, and the patellar surface all serve as articular surfaces that allow for flexion, extension, anterior-posterior sliding, and internal-external rotation of the knee. The knee may bend and straighten because it is a hinge joint. The knee, like all hinge joints, is reinforced by a set of collateral ligaments on either side of the joint. Cruciate ligaments connect the extremities of the femur and tibia, keeping them in their opposite positions. The knee is particularly vulnerable to frontal impacts and rotations due to its thin anterior covering and lack of strong muscle protection. At present, magnetic resonance imaging (MRI) is the best non-invasive diagnostic tool for evaluating internal knee dysfunction [1-5]. Although arthroscopy can be utilized for both diagnosis and treatment, it is intrusive and expensive and provides only a partial picture of the extracapsular soft tissues surrounding the joint. Internal knee derangements and other knee disorders have long been diagnosed with the help of arthroscopy and arthrography. Despite MRI’s rising prevalence in the examination of knee lesions, its diagnostic value is limited ^[6].

The purpose of this study was to compare the diagnostic accuracy of arthroscopy, MRI, and clinical assessment for traumatic knee diseases (Chart 1).

A prospective study was conducted in the Orthopaedics Department at Chettinad hospital and research institute between September 2022 and August 2023. There were a total of 30 patients, whom had experienced knee pain, instability, or other symptoms like locking or giving way following an episode of trauma. After gathering the patient history and performing a thorough physical examination, MRI of the knee was performed. Senior radiologist had examined the images thoroughly and reported his results which was confirmed by the senior orthopedic surgeon. Arthroscopy patients were evaluated and prepared for surgery.

A total of 30 patients (24 men and 6 women) were evaluated. Among the patients were those as young as 18 and as old as 60. The MRI and arthroscopy findings were compared (Table 1) to determine which diagnosis was more likely to be accurate.

The diagnostic accuracy of each technique was determined (Table 2 and 3).

 Patients between the ages of 25 and 38 made up the largest demographic of those who required treatment for knee injuries. Among the patients analyzed, lower leg twisting injuries were prevalent, with the most common causes being car accidents (40%), fall from stairs (26.6%), sports injuries (13.3%), and other causes (20%). When compared to the gold standard of arthroscopic inspection, the MRI showed a sensitivity of 93.87%, a specificity of 91.54%, an accuracy of 92.5%, and a negative predictive value (NPV) of 95.5% (Table 2).

Medical records of patients with pre-existing joint problems were used for this study. On MRI, we identified 17 cases of medial meniscus (MM) damage, however, arthroscopy confirmed only 15 (Fig. 1). The diagnostic accuracy of arthroscopy and MRI for medial meniscal tears is very similar; MRI has a sensitivity of 100% and a specificity of 86.6%. The predicted range of values was 88% positivity, 100% negativity, 88% sensitivity, and 88% specificity. In a study conducted by Elvenes et al., MRI was reported to have a sensitivity of 100%, specificity of 77%, a positive predictive value (PPV) of 71%, and an NPV of 100% for MM ^[7], while for lateral meniscus (LM), these values were found to be 40%, 89%, 33%, and 91%, respectively. MRI’s overall accuracy for both MM and LM was 84%. The NPV (100%) and PPV (88.2%) of arthroscopy are both excellent, and its sensitivity (100%) and specificity (86.6%) are also excellent. Our results show that arthroscopy outperforms MRI in terms of sensitivity, specificity, and predictiveness, whereas MRI fares worse in terms of its positive and NPVs. Of the 13 patients in our study with lateral meniscal injuries, 9 underwent successful arthroscopic surgeries (Fig. 2). Comparing arthroscopy with MRI, the former was 100% sensitive and the latter was 80.9% specific. MRI demonstrated a moderate connection with arthroscopy for the diagnosis of lateral meniscal injury. MRI has a 69.2% positive and 100% negative injury detection accuracy for the LM. Incorrect positive and negative diagnoses were more common when the MM was torn, but not when the LM was injured. There could be a number of factors for the unexpected MRI menisci findings. Meniscal rips and degenerative changes first seem identical on MRI due to the abundance of strong signals within the meniscus. The articular surface tear of the meniscus is diagnosed by the stretched high signal line. The signal from the inferior genicular artery might also be misinterpreted, leading to erroneous MRI results for the LM. Misdiagnosis as popliteal bursitis or Humphreys’ ligament damage is a common occurrence when a posterior LM injury is present^[3]. The anterior cruciate ligament was the site of injury in 22 of 30 MRI of patients with knee injuries (Fig. 3). MRI has a sensitivity of 88%, a specificity of 100%, and a 100% significant association with arthroscopy for detecting ACL injuries. MRI has a perfect PPV of 100%. Value in predicting failure is 62.5% negative. MRI provides a 93–97% detection rate for ACL injuries. MRI was found to have a 100% PPV and a 62.5% NPV in our study. Estimates of accuracy, sensitivity, and specificity for knee lesions have a wide range across the literature. A single ACL tear was detected with a sensitivity of 93%, as described by Rubin et al. ^[8]. Several prospective studies have demonstrated that MRI has a high potential for accurately diagnosing a torn ACL, with a sensitivity of 92–100% and a specificity of 93–100%. Rose and Gold. ^[9] observed that clinical evaluation was just as reliable as MRI in identifying meniscal tears and ACL ruptures; hence, they concluded that MRIs were unnecessary in patients with a clinical suspicion of these injuries due to their high cost. According to Boden et al. ^[2], if meniscus injury has already been diagnosed clinically, an MRI will not alter therapeutic options. Since the posterior cruciate ligament (PCL) was not damaged in any of the cases, imaging techniques (MRI and arthroscopy) show that it functions normally. The diagnosis of PCL rips with MRI has been shown to be accurate. This may be predicted because the PCL is typically thought of as a continuous, low-signal, homogeneous structure. Many studies have demonstrated a PPV of 99–100% and a NPV of 0%. Our study likewise had a 100% PPV, 100% NPV, 100% sensitivity, and 100% specificity [10, 11]. The severity of cartilage abnormalities cannot be disguised by arthroscopy as a standalone diagnostic method ^[12]. This shows that arthroscopic examination is more accurate than radiography or MRI at grading osteoarthritis and detecting anomalies in the surface cartilage. Retrospectively collecting MRI data, after noting arthroscopy results, enhanced the test’s sensitivity (from 40% to 71%), as discovered by Ochi et al. ^[13]. The computed sensitivity of MRI in cases of full-thickness cartilage loss and severe deep erosions in chondral lesions was 100% and 75%, respectively. However, arthroscopic imaging was unable to detect fibrilization or tiny lesions on the skin’s surface. Mori et al. stated that newer, more precise methods can help distinguish between partial and full-depth chondral damages in addition to displaying the degree of chondral lesions ^[14].

This study demonstrates that MRIs frequently misdiagnose individuals with multiple knee injuries or fail to detect a lesion while doing a diagnostic evaluation. Therefore, if the MRI comes out normal, there’s no reason to deny arthroscopic evaluation to the patient. Due to this MRI flaw, researchers have determined that arthroscopy can be performed following a comprehensive clinical assessment without the need for an MRI.

This study provides valuable insights for clinicians, enhancing diagnostic accuracy, preoperative planning precision, informed decision-making, resource optimization, and the continual improvement of diagnostic modalities in orthopedic practice