Prospective evaluation of the McMurray test PETER J. EVANS,* MD, PhD, G. DOUGLAS BELL, MD, FRCS(C), AND CY FRANK, MD, FRCS(C)

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1 Prospective evaluation of the McMurray test PETER J. EVANS,* MD, PhD, G. DOUGLAS BELL, MD, FRCS(C), AND CY FRANK, MD, FRCS(C) From the Division of Orthopaedic Surgery and Sport Medicine Centre, University of Calgary, Calgary, Alberta, and the *Division of Orthopaedic Surgery, University of Toronto, Toronto, Ontario, Canada ABSTRACT The accuracy and interexaminer reliability of the Mc- Murray test for the diagnosis of meniscal tears were compared with arthroscopic findings in a prospective study of 104 consecutive patients awaiting elective arthroscopy. The only significant McMurray sign found to correlate with meniscal injury was a "thud" elicited on the medial joint line with a medial meniscal tear (P 0.05) that had a fair interexaminer reliability (kappa 0.35). The sensitivity of a medial thud was 16%, and the specificity was 98% with a positive predictive value of 83%. Examiner experience had little effect on the accuracy of diagnosis of medial meniscal tears. This study supports the continued but limited emphasis on the McMurray test in the clinical diagnosis of meniscal tears. T. P. Mcmurray&dquo; described a test for meniscal tears of the knee in his lecture, entitled &dquo;the Semilunar Cartilages,&dquo; to the Royal College of Surgeons of England in Since that time, the McMurray test has been used as one of the primary diagnostic tests in the surgical decision-making process for meniscal tears. The validity of the McMurray test and its modifications have been questioned previously. Many articles have assessed the accuracy of a clinical diagnosis of meniscal tears. Apley2 reported on his test for meniscal tears using the prone position with knee joint compression or distraction with rotation. Apley compared the results of this &dquo;grind test&dquo; and &dquo;distraction test&dquo; with &dquo;orthodox methods&dquo; that included the McMurray test. His test was shown to be useful when false-negative orthodox methods were obtained, but he did not specify his statistical methods of comparison. Jackson and Abe,9 DeHaven and Collins, Daniel et a1.,4 and others7,14,15 have reported that arthroscopy is the most t Address correspondence and repnnt requests to: Peter J. Evans, MD, 262 Wobum Avenue, Toronto, Ontano, Canada, M5M 1 K9 604 accurate means of diagnosing meniscal injury; however, in their comparisons with clinical diagnoses, they did not comment on the McMurray test specifically.4,5,9 In a prospective study in 1980, Noble and Erat12 found that the McMurray test was positive in 62.1% of vertical or oblique tears, in 63% of horizontal tears, and in 41.7% of normal menisci. They noted the &dquo;absence of any reliable clinical pattern differentiating between the patients with a torn meniscus and those without Medlar et al.11 and Barry et a1.3 found that the McMurray test was positive in only 45% to 50% of patients with a suspected meniscal tear. In 1986, Anderson and Lipscomb reported on 100 patients with suspected meniscal tears undergoing scheduled arthroscopy. A McMurray test was positive in 58% and false-negative in 38%. False-negatives were attributed to locked knees and to those with flexion limited by pain. Collectively, these reports suggest a low sensitivity and specificity for the McMurray test, but to date no analysis of the interobserver reliability has been performed. The method of performing the McMurray test has been revised by some authors, most notably Hoppenfeld. As originally described by Mcmurray,&dquo; the &dquo;simplest routine is to bring the leg from its position of acute flexion to a right angle, whilst the foot is retained first in full internal, and then in full external rotation.&dquo; To examine the right knee, the left hand is placed on the knee with the thumb over the lateral joint line and with the first and second fingers over the medial joint line while the right hand maintains the rotation of the tibia. The opposite is true for the left leg. Note that at no time is a valgus or varus stress applied to the knee. McMurray described a &dquo;thud,&dquo; palpable and produced by the loose fragment of meniscus caught between the femur and tibia during rotation. He also noted a &dquo;sensation&dquo; that was described by patients as reproducing their clinical symptoms. McMurray stated that most medial meniscal tears could be detected by eliciting a thud or sensation during manipulation of the knee in external rotation from full

2 605 flexion to 90. Conversely, lateral meniscal tears could be detected by eliciting a thud or sensation during manipulation of the knee in internal rotation from flexion to 90/ McMurray also stated that by &dquo;altering the position of flexion of the joint the whole of the posterior segment of the cartilages can be examined from the middle of their posterior attachments.&dquo; The degree of flexion was thought to correlate with the position of the tear in the anterior-posterior plane. Extending the knee beyond 90 to look for signs of tears in the anterior segment of the cartilages was believed to be inaccurate. The purpose of this study was to determine prospectively the sensitivity and specificity of the McMurray test in predicting and localizing meniscal tears, as well as to determine its interexaminer reliability, using arthroscopic diagnosis as the designated standard. The frequency of a positive test in apparent normal controls was also studied. MATERIALS AND METHODS Patient selection Two populations were studied. The first population (normal controls) consisted of 60 medical students who did not undergo arthroscopic surgery, giving a total of 120 knees examined. Of these 120 knees examined, 25 knees with previous injuries were eliminated from the study. Ninetyfive knees had no history of a previous injury and had no symptoms present at the time of examination. The second population consisted of 104 consecutive patients awaiting elective arthroscopic surgery, giving a total of 104 knees examined. All patients had been booked for arthroscopy for a variety of reasons based on a previous history and physical examination. Conditions other than just the suspected meniscal tears were included for insight into the true sensitivity and specificity of the test in symptomatic knee examination. Patient examination and surgery Each patient had a McMurray test that was performed independently by two examiners before a repeat history was taken on admission to eliminate the influence of the history on the interpretation of each test. Examiners included the senior author (GDB), who has been in clinical practice for 10 years, and a medical student (PJE), who was taught the McMurray test specifically and who had ample opportunity before this investigation to practice it according to Mc- Murray s descriptions. In this study, therefore, each knee was assessed by both examiners in the fashion originally described by McMurray. If a thud or a sensation was elicited, it was recorded according to side, degree of flexion, and direction of rotation of the tibia. While pain is not part of the McMurray sign, it has been commonly interpreted as part of meniscal testing, and hence its production by the maneuver was also recorded in our series; however, we did not consider the test as being positive with pain alone. The operative group underwent arthroscopic surgery by one surgeon (GDB) and the type (longitudinal, horizontal, and radial) and position (posterior third, posterior two thirds, anterior two thirds, and anterior third) of a tear were recorded. These findings were then compared with the preoperative McMurray test findings. Statistical analysis Analysis of the McMurray test was done by a two-tailed analysis using the chi-square test (with the Yates correction) and the Fisher s exact test, where appropriate. The interexaminer reliability was analyzed by the kappa test.13 The clinical findings of thud and sensation were first compared with arthroscopic findings for each examiner. Subsequently, only when both examiners elicited a positive sign was this considered to be a positive finding and was compared with meniscal injury. Only when both did not elicit a sign was the finding considered to be negative. From this second analysis, the overall accuracy of the test was derived. RESULTS Control results Of the assumed normal knees, five knees were found to have a positive McMurray sign by only one examiner (PJE) and eight knees by only the second examiner (GDB). Only three knees were found to have a positive McMurray sign by both examiners. Arthroscopy results In the 104 knees undergoing arthroscopy, meniscal injury was found in 59 patients (56%), and it was localized to the medial meniscus in 47 (80%), and to the lateral meniscus in 12 (20%). Some menisci had multiple tears present, making a total of 69 individual tears. The types of tears on the medial meniscus included 81% longitudinal, 7% radial, and 11 % horizontal tears, while on the lateral meniscus these were 33%, 47%, and 20%, respectively. McMurray test for detection of actual tear sites Of the 69 tears, the site was localized arthroscopically to the posterior third in 29 cases (42%), spanning the posterior two thirds in 27 cases (39%), the middle third alone in 9 cases (13%), spanning the anterior two thirds in 3 cases (4%), and the anterior alone in 1 case. Similarly, 92% of the McMurray signs were elicited predominantly from the posterior segment (full flexion to 120), while only 6% were in the middle segment (60 to 120 of flexion), and 2% were in the anterior segment (0 to 60 of flexion). This indicates that most McMurray signs and actual injuries occurred at the posterior portion of the meniscus.

3 606 McMurray test results Of the 104 knees having subsequent arthroscopy, there were 51 with a positive McMurray sign (either sign, either side, either examiner), 46 with a positive McMurray thud, 29 with a sensation, and 24 with both signs present (either side, either examiner); 9 had a positive McMurray test by 1 examiner alone (GDB), 20 by the second examiner alone (PJE), and 20 by both examiners. Which sign is best? Tables 1 and 2 demonstrate the degree of association between eliciting a thud or sensation and a tear on either the medial or lateral meniscus. With the knee in the externally rotated position, only a thud elicited on the medial joint line was associated significantly with medial meniscal tears (P 0.05; Table 1). With the knee in the internally rotated position, a lateral thud was not associated significantly with lateral meniscal injury (Table 2). Sensation was not significant on either joint line. Rotation and laterality. McMurrayl0 described the detection of medial tears by medial joint line signs with the tibia externally rotated as we have presented (Table 1); however, no mention was made of other possibilities. In this study, the signs elicited on the lateral joint line with the tibia externally rotated were too few to be associated significantly. Similarly, with the tibia internally rotated, neither medial nor lateral joint line signs were significantly associated with medial tears (data not shown). McMurray detected lateral tears by lateral joint line signs elicited with the tibia internally rotated. In the current study, this association was not shown (Table 2). In addition, significant association between medial joint line signs and lateral tears when the tibia was held and internally rotated was not found. Similarly, with the tibia externally rotated, neither medial nor lateral signs were significantly associated with lateral tears (data not shown). Interexaminer reliability. The reliability between examiners using the McMurray test is shown in Tables 1 and 2. The kappa test consists of six levels of agreement, ranging from poor to almost perfect. The degree of agreement in detecting a thud was fair on the medial and slight on the lateral joint line. The degree of agreement for sensation was poor on both joint lines and fair for pain on both joint lines. Table 3 demonstrates the effect that clinical experience has on the accuracy of diagnosing medial meniscal tears with the McMurray test. A medial thud elicited by the McMurray maneuver was associated significantly with medial meniscal tears by the less experienced examiner only, whereas medial sensation and pain were associated significantly with medial meniscal tears by the experienced examiner only. Accuracy of the McMurray test. The clinical accuracy of the McMurray test was assessed only for a medial joint line thud because sensation on both joint lines and thud on the lateral joint line were not significant. Table 4 illustrates that when a medial thud is elicited the likelihood afterward of the presence of a medial meniscal tear is 83% (positive predictive value); however, when a medial meniscal tear was present a medial thud was elicited only 16% of the time (sensitivity). When a medial thud was not present, the likelihood afterward of the presence of a medial meniscal tear was 65% (negative predictive value). When no medial tear was present, no medial thud was elicited (specificity) 98% of the time. DISCUSSION This is the first study to correlate prospectively and systematically the medial and lateral joint line signs elicited by the McMurray maneuver with meniscal injury and determine the interexaminer reliability of the test. The findings of the present study support the continued but limited emphasis on the McMurray test in the clinical diagnosis of meniscal tears. Examination of our group of 95 normal knees revealed only 3 cases that both examiners agreed had a positive McMurray test. Particular concern would be expressed regarding the McMurray test if false-positive findings of TABLE 3 Effect of examiner experience on diagnosis of medial meniscus injury&dquo; TABLE 1 Signs elicited in external rotation with medial meniscus injury&dquo; TABLE 2 Signs elicited in internal rotation with lateral meniscus injury&dquo; TABLE 4 Accuracy of medial thud elicited in external rotation and lateral pain elicited in internal rotation

4 607 greater than 3% to 4% in normal knees had been found. We believe that this is the lst report of the McMurray test in knees deemed normal by history-normal being a negative history of injury or symptoms or any other pathologic signs. The 3 positive McMurray tests found may have been a result of a hypermobile but normal meniscus, an asymptomatic torn meniscus, or some other asymptomatic problem. Noble and Erat12 statistically analyzed a myriad of symptoms and signs, including the McMurray test, and were unable to find a reliable way of clinically diagnosing meniscal tears. They reported a 62.1% incidence of a positive Mc- Murray sign in patients with a vertical or oblique tear, a 63% incidence in patients with a horizontal cleavage tear, and a 41.7% incidence in patients with normal menisci at the time of surgery. Barry et al.3 looked at many signs and symptoms as well as radiographic findings and preoperatively allocated patients into either a definitive or dubious tear group. They found a 40% incidence of a positive McMurray sign in their definite tear group, all of whom had a tear present at surgery. The dubious tear group had a 28% incidence of a positive McMurray sign preoperatively, but only 7 had a tear present at surgery. Barry et al. did not statistically evaluate the predictive power of the McMurray test. Medlar et ail.&dquo; reported a preoperative finding of a positive McMurray sign in 11 of 26 children who underwent meniscectomy, but they did not comment on its accuracy in predicting the 15 tears found at surgery. Anderson and Lipscomb compared the accuracy of a new medial-lateral grind test with the accuracy of the McMurray test. Of 100 patients examined preoperatively, they reported a high yield of 93 meniscal tears found at arthroscopy. They found the McMurray test to be positive in 58%, and there were 5 false-positives and 38 false-negatives. There was no statistical measure of the degree of association between the McMurray test and meniscal tears, nor was there any measure of the predictive power of the test. In a recent prospective study by Fowler and Lubiner, the McMurray test was demonstrated to have a sensitivity of 28.8% and a specificity of 95.3%, and to be negatively correlated with a diagnosis of chondromalacia patella. Unfortunately, there was no breakdown as to the test accuracy in diagnosing medial versus lateral tears. This study has demonstrated that the McMurray test was not useful in diagnosing lateral meniscal tears. Although lateral joint line pain that was elicited using the McMurray maneuver in internal rotation was associated significantly with lateral meniscal tears (P 0.03; Table 2), the positive predictive value was only 29% (Table 4). This indicates that pain is reproducible in but not predictive of meniscal injury. Eliciting a sensation, similar to that when the patient s knee gave way previously, was of no value in diagnosing meniscal tears. Medial meniscal tears were accurately diagnosed by eliciting a thud using the McMurray test with the tibia in the externally rotated position and the knee between full flexion and 120 of flexion (P 0.05). A medial thud was very predictive (83%) of a medial meniscal tear, but unfortunately the sensitivity was very low (16%). Therefore, a torn medial meniscus would be missed in many patients if one solely relied on the McMurray test. We found a lower sensitivity (16%) than other reports in the literature, likely because our patient entry criteria included patients with various knee complaints, not just those with suspected or proven meniscal tears as in most other studies. We believe this more fairly represents the use of the McMurray test in its clinical role of aiding in the diagnosis of meniscal tears in patients with knee complaints. Importantly, the specificity of the test was high (98%), which indicates that false-negative signs from other injuries of the knee, such as synovial plica, osteochondral articular flaps, inflammatory popliteal tendinitis, loose bodies, or clunks associated with iliopsoas or iliotibial band snapping, rarely occurred. Like many other examination techniques, the McMurray test is quite subjective. The interexaminer reliability of medial thud was only fair (kappa 0.35), demonstrating the low level of agreement between the two examiners. In addition, examiner experience did not have an effect as evidenced by the fact that only the less experienced examiner accurately diagnosed medial meniscal tears by eliciting a medial thud. It is of interest that the more experienced examiner accurately diagnosed medial meniscal tears by eliciting a sensation and pain with the McMurray maneuver, again emphasizing the subjective nature of the test. It is possible that the amount of force applied with the McMurray maneuver may influence the pain and sensation response elicited, thus further emphasizing the subjectiveness of the test. At best, the McMurray test will aid in the diagnosis of a medial meniscal tear, but, in view of the low sensitivity and fair interexaminer reliability of the test, it cannot be considered as the diagnostic standard in the decision for arthrotomy or arthroscopy. Despite ever-increasing sophistication of noninvasive and invasive diagnostic procedures, physical examination remains the first important test for a patient. We hope that the improved knowledge of the McMurray test s accuracy will assist in putting physical examination on a more scientific basis. Many other commonly used physical diagnostic tests should be similarly evaluated. REFERENCES 1. Anderson AF, Lipscomb AB: Clinical diagnosis of meniscal tears. Description of a new manipulative test. Am J Sports Med 14: , Apley AG. The diagnosis of meniscus injuries. J Bone Joint Surg 29: 78-84, Barry OCD, Smith H, McManus F, et al. Clinical assessment of suspected meniscal tears Ir J Med Sci 152: , Daniel D, Daniels E, Aronson D: The diagnosis of meniscal pathology. Clin Orthop , DeHaven KE, Collins HR: Diagnosis of internal derangements of the knee J Bone Joint Surg 57A: , Fowler PJ, Lubiner JA The predictive value of five clinical signs in the evaluation of meniscal pathology. Arthroscopy 5: , Gillies H, Seligson D: Precision in the diagnosis of meniscal lesions: A comparison of clinical evaluation. Arthrography and arthroscopy. J Bone Joint Surg 61A: , 1979

5 Hoppenfeld S: Physical Examination of the Spine and Extremities. Norwalk, CT, Appleton-Century-Crofts, 1976, pp Jackson RW, Abe I : The role of arthroscopy in the management of disorders of the knee J Bone Joint Surg 54B , McMurray TP: The semilunar cartilages. Br J Surg , Medlar RC, Mandiberg JJ, Lyne ED. Meniscectomies in children Report of long-term results (mean 8.3 years) of 26 children. Am J Sports Med 8: 87-92, Noble J, Erat K: In defence of the meniscus J Bone Joint Surg 62B: 7-11, Rosner B: Fundamentals of Biostatistics. Boston, PWS-Kent Publishing, 1989, pp Shakespeare DT, Rigby HS: The bucket handle tear of the meniscus J Bone Joint Surg 65B: , Tregonning RJA. Diagnostic arthroscopy of the knee joint. Meniscal findings in a prospective study of 200 examinations. N Z Med J , 1981