Comparison of Thessaly Test with Joint Line Tenderness and McMurray Test in the Diagnosis of Meniscal Tears

Introduction: Meniscus injuries are the most frequent problem of the knee. The aim of this study was to investigate the accuracy of the Thessaly test and comparing it with those of McMurray and Joint-line tenderness tests for diagnosing meniscal tears. Materials and methods: This study was designed as a prospective observational one done in an outpatient clinic at a university hospital. 106 patients with knee pain and 82 age-matched control were included during study period (from February 2014 to January 2015). Each patient was clinically examined with McMurray, Thessaly, and joint line tenderness tests. Then, the findings were matched by MRI and arthroscopic findings. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated as main outcomes. Results: Based on MRI, Thessaly was the most sensitive for medial meniscus tears (56.2%), while McMurray and joint-line tenderness were more specific (89.1% and 88.0%, respectively). For lateral meniscus tears, McMurray was the most sensitive (56.2%) and all were specific (McMurray 89.6%, Thessaly 88.4%, joint-line tenderness 90.2%). With arthroscopy, Thessaly was the most sensitive for medial meniscus (76.6%), while McMurray and joint-line tenderness were more specific (81.0%, and 81.0%). Agreement with arthroscopy was the highest with McMurray (for medial meniscus kappa=0.40, p<0.001, and for lateral meniscus kappa=0.38, p=0.002). Conclusion: The Thessaly can be used to screen for medial meniscus tears. McMurray and joint-line tenderness should be used for suspected medial meniscus tears. For lateral meniscus, McMurray is appropriate for screening and all the tests are useful in clinic.


INTRODUCTION
Knee pain comprises approximately one third of all outpatient physical therapy visits 1 of which 9% are associated with meniscal lesions 2 . A combination of subjective symptoms increases the predictive value of recognising meniscal lesion to 70-80%, but patient history is not enough for accurate diagnosis 3 .
Various physical tests have been described in the literature: the McMurray's, the Apley compression and distraction, and the joint line tenderness test with their adaptations are known examples [4][5][6][7][8][9][10][11][12][13][14] . The diagnostic accuracy of the clinical tests may improve with compressive forces applied to the knee joint with weight-bearing axial compression 15,16 . Medial joint line tenderness, knee locking, daily pain and work absence have been reported to predict 61% of meniscal tear confirmed by arthroscopy 3 .
More recently, the Thessaly test was suggested to be safely used as a first line screening test for identifying the candidates of arthroscopic meniscal surgery. The test also was reported to have a lower false positive and false negative compared to other clinical tests 16 . On the other hand, MRI is considered as the diagnostic method of choice because of providing a reliable non-invasive tool in identifying common knee pathology 4,17 . Arthroscopy is also the gold standard for the diagnosis of meniscal lesions, with 90-95% accuracy 18 . In addition, arthroscopy provides simultaneous therapeutic possibilities.

Comparison of Thessaly Test with Joint Line Tenderness and McMurray Test in the Diagnosis of Meniscal Tears
Low specificity, sensitivity, and diagnostic accuracy of the clinical tests may leave meniscal lesions undetected. The methodological quality of the studies on the clinical tests has a significant effect on reported sensitivities and specificities as well 2,19 .
High cost and false positives are the disadvantages of MRI for the diagnosis of meniscal lesions 4,20 . A false positive of 65% for identifying medial meniscal tears and 43% for lateral meniscus tears have been estimated for MRI when compared with surgical findings 21 . Even, some researchers believe that MRI is not superior to physical examination in the diagnosis of meniscal tears 20 . Invasiveness and high cost are the major drawbacks for common use of arthroscopy too 4 .
Therefore, we need less expensive, non-invasive, and more accurate methods of identifying meniscal lesions. The optimal clinical tests and measures should be selected with high sensitivity and specificity. The aim of conducting the present study was to investigate the accuracy of the Thessaly test in screening for meniscal tears. We examined whether the Thessaly test alone or in combination with other clinical tests could provide a non-invasive means of identifying lesions.

MATERIALS AND METHODS
The present study was designed as a prospective observational one which was conducted from February 2014 to January 2015 in an outpatient clinic of physical medicine and rehabilitation at the university hospital; Imam Reza, a large referral practice and research centre in Tehran. The study protocol was approved by the institutional review board (IRB) of AJA University of Medical Sciences and we obtained ethics approval from the local ethics committee before the study was commenced. All the participants read and signed an informed consent form prior to study involvement.
Consecutive patients aged more than 15 years who had a current knee pain or discomfort, history of swelling or effusion, knee locking, or clicking sensation on movement of the knee were enrolled in the study. Exclusion criteria included individuals with a previous history of knee surgery or arthroscopy, and the radiologic evidence or clinical manifestations of osteoarthritis and rheumatologic diseases. In addition, we excluded patients if they could not attend the clinical examinations and did not take MRI or refused arthroscopy.
At the first visit and according to predetermined inclusion and exclusion criteria patients were screened for eligibility. From 220 eligible patients, 106 completed the tests and composed our analytic sample. We also selected 100 age-matched participants as the group control from which 82 completed the study. The control group was randomly selected from patients who came to the clinic for complaints other than knee problems (e.g., pain in their shoulders).
At the beginning of the study, research staff was briefed. Our clinical assessors were two specialists of physical medicine and rehabilitation. The study was carried out under the supervision of two board-certified physical medicine and rehabilitation specialists, and an associate professor of radiology.
Patients were interviewed to obtain their past medical histories. The presence of the symptoms and signs of meniscal lesions and other knee problems were questioned. In addition, the recruitment questionnaire asked about consultation with a physician and active or previous treatment and surgery. Then our clinical assessors performed physical examinations and conducted further investigations for the diagnosis of meniscal lesions. We recorded any pain or discomfort, clicking sensation or locking on movement, and swelling and injury of the knee.
For the Thessaly test, participants were instructed to stand while supported by holding their hands. Thereafter, they were guided to perform internal and external rotation of the knee and body in three occasions during which the knee was flexed at almost 20°. We considered the test as positive when the patients had medial or lateral joint-line discomfort or experienced locking in the knee 4 . For all the participants, we performed McMurray and joint line tenderness at the lateral and medial sides. Further investigations including MRI were ordered and lesions were graded 22 . Then, the patients with suspected meniscal lesions were referred to arthroscopy for definitive diagnosis and appropriate treatment.
We used a block design to randomise the patients to the observers. The investigators who performed physical examinations were blinded to patients' medical history. Moreover, the assigned radiologists also were unaware of the study question and patients' medical history.
All statistical analyses were performed with the Statistical Package for Social Sciences version 16.0 [SPSS Inc, Chicago, IL, USA]. The distribution of variables was analysed with Kolmogorov-Smirnov test. Continuous data are presented as mean and standard deviation, and categorical data, as numbers and proportions. We used Chisquared and t-test to assess differences in demographic characteristics between the two groups. Sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, the accuracy of diagnoses, and diagnostic odds were calculated by forming two-by-two cross table and using standard formula. Combinations of the tests were also evaluated statistically to find the best diagnostic strategy in the clinic. A p-value of less than 0.05 was considered significant.

RESULTS
A total of 188 patients were included in the study. The mean age of the patients in was found to be 23 (Table II) demonstrates the diagnostic parameters based on the results of knee arthroscopy. We also measured the agreements between the results of the clinical tests and arthroscopy for the diagnosis of meniscal tears (Table III).

DISCUSSION
Meniscal tears are the result of injury or degeneration of the substance of the meniscus. Majority patients with meniscal tears complain of an acute onset of sharp pain following a twisting injury with the knee flexed and the foot planted on the ground 23 . The diagnosis of meniscus tear can frequently be made from a careful history, physical examination and appropriate diagnostic tests. There are various provocative manoeuvres or tests to elicit symptoms from a torn meniscus,   Our sample was sufficiently large to detect important differences among the diagnostic parameters. Our research team and assessors were highly trained, and they attempted to follow diagnostic protocols strictly. Meanwhile, ethical considerations prevent us to perform arthroscopy when it was not necessary. Therefore, we were not able to compare the clinical tests with the gold standard for all participants.

CONCLUSION
Our study showed that the Thessaly is a sensitive clinical test for the diagnosis of medial meniscus tears. Therefore, the test can be used to screen general population. On the other hand, McMurray and joint-line tenderness are more specific and should be used to diagnose medial meniscus tears in patients with the related clinical manifestations. For lateral meniscus tears, the McMurray test is appropriate for screening and all the three tests are useful in the physical examination of patients with the suspected tears. Therefore, with regard to sensitivity, specificity, and accuracy, the Thessaly should be used along with the other tests. Overall, we did not find important difference in the diagnostic usefulness of the three tests and prefer to use the tests combined. The tests combined have a high proportion in agreement with arthroscopy and are valuable in the detection of meniscal and the cruciate ligament lesions.

ETHICAL CONSIDERATION
Ethics approval was obtained from the institutional review boards, and the study protocol was carried out in accordance with the Declaration of Helsinki. The rationale of the study was explained to all participants. Patients were informed that they were free to withdraw from the study at any time. A trained study nurse accompanied patients, and provided patients with verbal information if needed, and a leaflet on the diagnostic procedures to eligible participants. All patients gave written informed consent.