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The importance of the valgus stress test in the diagnosis of posterolateral instability of the knee
Injury, Int. J. Care Injured (2006) 37, 1011—1014
www.elsevier.com/locate/injury
The importance of the valgus stress test in the diagnosis of posterolateral instability of the knee Tamir Pritsch a,*, Nehemia Blumberg b, Amir Haim a, Shmuel Dekel a, Ron Arbel b a
Department of Orthopaedic Surgery B’, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel Department of Orthopedic Surgery B’, Sports Medicine Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
b
Accepted 13 March 2006
KEYWORDS Knee; Posterolateral instability; Dial test; Valgus stress; Medial collatera ligament
Summary Background: The diagnosis of posterolateral instability of the knee is often based on a typical indirect mechanism of injury, a history of ‘‘giving way’’ and a positive dial test. Our search of the English literature revealed no mention of including the valgus stress test in the diagnostic protocol for posterolateral instability. Hypothesis: Based on our experience, we hypothesised that a medial collateral ligament (MCL) tear will also produce a positive dial test and that a valgus stress test would provide differential diagnostic information. Methods: The MCL’s of 14 fresh cadaveric knees (7 cadavers) were cut to simulate a grade 3 tear, taking care not to damage the medial retinaculum or the posteromedial stabilisersrs of the knee. The amount of tibial external rotation (the dial test) was measured for each knee before and after transection of the MCL. Results: The results of the dial test after transection of the MCL were similar to those stemming from a solitary injury to the posterolateral corner. There was a significant increase in external rotation of the knee in 308 and 908 of flexion. More over, external rotation in 308 was significantly greater than external rotation in 908 of knee flexion. Conclusions: Whenever suspecting a posterolateral complex injury, one has to carefully perform a valgus stress test in 08 and 308. Although the support of a clinical study is needed in order to make a definite conclusion, the dial test is probably not reliable in the presence of medial instability, and alternative diagnostic measures should be used. # 2006 Elsevier Ltd. All rights reserved.
* Corresponding author at: Department of Orthopaedic Surgery B’, Tel Aviv Sourasky Medical Center, 6 Weitzman St., Tel Aviv 64239, Israel. Tel.: +972 3 6974727; fax: +972 3 6074546. E-mail address: [email protected] (T. Pritsch). 0020–1383/$ — see front matter # 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2006.03.009
1012
T. Pritsch et al.
Introduction
Table 1 The mean results of the dial test before and after transecting the medial collateral ligament (MCL)
Injuries of the posterolateral corner of the knee are infrequent. They can cause severe disability due to both instability and articular cartilage degeneration. The dial test (posterolateral rotation test) is the usual element of the physical examination specific to the evaluation of posterolateral instability; it was shown to provide a good assessment of the extent of posterolateral knee damage.4,5,13 The dial test was first described by Gollehan et al.4 It can be performed with the patient in a prone or supine position. The thigh is stabilised and a rotational force is applied through the foot and ankle. The examiner then looks for the extent of external rotation of the tibial tuberosity, and compares it with the contralateral healthy knee: an increase of >108 in external rotation at 308 of knee flexion compared with the contralateral side indicates a posterolateral knee injury. The test is then repeated at 908 of knee flexion. Normally, in an isolated posterolateral knee injury, there is less external rotation of the tibia at 908 than at 308.10 Greater external rotation of the tibia at 908 is indicative of a combined posterior cruciate ligament (PCL) and posterolateral corner injury.4,5,13 During the past year, we encountered two patients who underwent posterolateral corner reconstruction and still complained of persistent instability. On physical examination, both patients had positive dial tests and valgus opening at 08 and 308 of knee flexion, consistent with grade 3 medial collateral ligament (MCL) tears. The anteroposterior stability was intact. Both patients were operated elsewhere, and we retrieved their medical records: the diagnosis of posterolateral corner injury was apparently based on a history of indirect trauma to the knee, complaints of instability and a positive dial test. The purpose of this study was to find out whether the results of the dial test in a grade 3 MCL tear are similar to those of an injury to the posterolateral corner of the knee.
Dial test
Materials and methods Both knees of seven fresh frozen cadavers of individuals with no medical record of knee surgery or instability were studied. The stability of each knee was first verified by applying the anterior drawer test, the Lachman test and a mediolateral stress at 08 and 308 of flexion. The dial test was then performed at 308 and 908 of knee flexion. It was carried out with the cadaver lying in a supine position and the examined knee flexed over the examination
MCL intact (n = 14) 308 Flexion 908 Flexion
Mean
8.358 8.428
MCL transected (n = 14) 308 Flexion 22.928 * 908 Flexion 19.868 * *
Standard deviation 1.277 1.398 3.26 1.96
p = 0.001 (Wilcoxon).
table. After stabilising the thigh, one examiner maximally externally rotated the leg while the other measured the amount of external rotation of the foot using a goniometer. Each measurement was taken three times and a mean was calculated. After examining the intact knees, the deep and superficial components of the MCL were cut, taking care not to dissect the posterior oblique ligament or the medial patellar reticulum. The dial test was then performed again at 308 and 908 of knee flexion using the same method for the measurements.
Statistics The Wilcoxon statistical test was used to analyse the results. A p value of <0.05 was considered significant.
Results The mean values for the dial test in the intact knees at 308 and 908 of flexion were 8.358 and 8.428, respectively. Cutting the MCL increased those values significantly (Table 1). The mean value of the dial test was 22.938 at 308 ( p = 0.0001) and 19.868 at 908 ( p = 0.0001). The differences between the results of the dial test at 308 and 908 of knee flexion, before and after transection of the MCL were also compared. After transecting the MCL, the external rotation of the tibia at 308 had increased by a mean value of 3.148 as compared to the external rotation at 908 ( p = 0.0006).
Discussion We carried out this study after having treated two cases of grade 3 MCL tears imitating posterolateral complex injury during the past year. Both patients described a typical mechanism of injury (indirect trauma), complaints of ‘‘giving way’’ and a positive dial test, and both underwent posterolateral recon-
Importance of the valgus stress test structions. They presented to our outpatient clinic due to continuous complaints of knee instability postoperatively. Recent reviews1,3,9 have considered the dial test to be almost pathognomonic for posterolateral complex injury. However, according to the results of this study, it is also positive in grade 3 MCL tears. Moreover, similar to the results of the dial test in an isolated posterolateral complex injury, the external rotation of the tibia at 908 of knee flexion was significantly less than at 308. Several biomechanical studies had found excessive external rotation of the tibia after transection of the MCL.8,11,14 However, most of them did not analyse their findings statistically and none looked at the difference in external rotation between 308 and 908 of knee flexion. Warren et al.14 performed a sequential transection of the MCL on cadaver knees and found an increase in tibial external rotation after transecting the long fibres. Kennedy and Fowler8 sectioned the deep portion of the medial collateral ligament in otherwise intact specimens. Although they noted instability, they did not record its extent. Matsumoto and Seedhom11 sectioned the MCL in three cadaveric knees and noted that external rotation was increased between flexion angles of 308 and 908 in two of the knees and throughout the range of flexion in the third knee. Haimes et al.6 measured the motion limits in human cadaveric knees before and after sectioning the anterior cruciate ligament (ACL) and the MCL. According to their results, cutting the MCL increased the external rotation limit, and the increase was independent of whether the ACL was intact. Hallen and Lindahl7 first sectioned the superficial portion of the MCL and then its deep portion and found a significant increase in total rotation of the tibia after sectioning the superficial part in an otherwise intact specimen. The results of our investigation are in agreement with the principle that compromise of the MCL leads to rotational instability of the tibia. A search of the English medical literature failed to uncover any mention of an MCL tear as part of the differential diagnosis of posterolateral instability, nor has it ever been recommended that a valgus stress test at 08 and 308 of knee flexion be performed after a dial test was found to be positive.1—3,9,10,12 Our findings demonstrated a statistically significant increase in the results of the dial test after transecting the deep and superficial part of the MCL as well as, a significant difference between 308 and 908 of knee flexion, thus mimicking an isolated injury to the posterolateral corner. An MCL tear probably causes excessive external rotation due to anterior translation of the medial tibial plateau,
1013 whereas posterolateral corner injury causes excessive external rotation due to subluxation of the lateral tibial plateau, however, the end result regarding the dial test is the same. We recognise that the amount of tibial rotation could have been determined more accurately by measuring the intermalleolar axis; however, the purpose of this study was to re-evaluate the Dial test, which is performed by external rotation of the foot. The advantage in a cadaveric study is the ability to create the exact injury that one wants to investigate. However, although measurements on cadaveric limbs are useful, they are somewhat different from the clinical scenario. The stability of the cadaveric knee relies only on the static stabilisers where as clinically, the surrounding muscles additionally contribute a very important dynamic stability. The results of this study should be supported by a clinical study before making definite conclusions, yet, according to our results, if medial instability compatible with a grade 3 MCL tear is diagnosed, the dial test might not be reliable, and alternative diagnostic tests for posterolateral instability should be used. We recommend performing a valgus stress test at 08 and 308 whenever a posterolateral complex injury is suspected. In addition, before undertaking a reconstructive procedure, it is recommended to perform magnetic resonance imaging of the knee, which can provide valuable evidence of MCL and posterolateral corner injury.
Acknowledgments We would like to thank the department of anatomy in Sackler Medical School, Tel Aviv University, for full cooperation and assistance. We would also like to thank Ms. Esther Eshkol for editorial assistance.
References 1. Chen FS, Rokito AS, Pitman MI. Acute and chronic posterolateral rotatory instability of the knee. J Am Acad Orthop Surg 2000;8:97—110. 2. Covey DC. Injuries of the posterolateral corner of the knee. J Bone Joint Surg A 2001;83:106—18. 3. Davies H, Unwin A, Aichroth P. The posterolateral corner of the knee. Anatomy, biomechanics and management of injuries. Injury 2004;35:68—75. 4. Gollehan DL, Torzilli PA, Waren RF. The role of the posterolateral and cruciate ligaments in the stability of the human knee: a biomechanical study. J Bone Joint Surg A 1987;69: 233—42. 5. Grood ES, Stowers SF, Noyes FR. Limits of movement in the human knee: effect of sectioning the posterior cruciate
1014
6.
7.
8.
9.
ligament and posterolateral structures. J Bone Joint Surg A 1988;70:88—97. Haimes JL, Wroble RR, Grood ES, Noyes FR. Role of the medial structures in the intact and anterior cruciate ligament-deficient knee. Limits of motion in the human knee. Am J Sports Med 1994;22:402—9. Hallen LG, Lindahl O. Rotation in the knee joint in experimental injury to the ligaments. Acta Orthop Scand 1965;36: 400—7. Kennedy JC, Fowler PJ. Medial and anterior instability of the knee. An anatomical and clinical study using stress machines. J Bone Joint Surg 1971;53A:1257—70. LaPrade RF, Wentorf FA. Diagnosis and treatment of posterolateral knee injuries. Clin Orthop 2002;402:110—21.
T. Pritsch et al. 10. Magee DJ, editor. Orthopedic Physical Assessment. Philadelphia: WB Sunders; 2002. 11. Matsumoto H, Seedhom BB. Rotation of the tibia in the normal and ligament-deficient knee. A study using biplanar photography. Proc Inst Mech Eng [H] 1993;207:175—84. 12. Miller III RH. Knee injuries. In: Canale ST, editor. Campbell’s Operative Orthopaedics. Philadelphia: Mosby; 2003. p. 2165—339. 13. Veltri DM, Deng XH, Torzilli PA, et al. The role of the cruciate and posterolateral ligaments in stability of the knee: a biomechanical study. Am J Sports Med 1995;23:436—43. 14. Warren LF, Marshall JL, Girgis F. The prime static stabilizer of the medial side of the knee. J Bone Joint Surg 1974;56A: 665—74.
www.elsevier.com/locate/injury
The importance of the valgus stress test in the diagnosis of posterolateral instability of the knee Tamir Pritsch a,*, Nehemia Blumberg b, Amir Haim a, Shmuel Dekel a, Ron Arbel b a
Department of Orthopaedic Surgery B’, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel Department of Orthopedic Surgery B’, Sports Medicine Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
b
Accepted 13 March 2006
KEYWORDS Knee; Posterolateral instability; Dial test; Valgus stress; Medial collatera ligament
Summary Background: The diagnosis of posterolateral instability of the knee is often based on a typical indirect mechanism of injury, a history of ‘‘giving way’’ and a positive dial test. Our search of the English literature revealed no mention of including the valgus stress test in the diagnostic protocol for posterolateral instability. Hypothesis: Based on our experience, we hypothesised that a medial collateral ligament (MCL) tear will also produce a positive dial test and that a valgus stress test would provide differential diagnostic information. Methods: The MCL’s of 14 fresh cadaveric knees (7 cadavers) were cut to simulate a grade 3 tear, taking care not to damage the medial retinaculum or the posteromedial stabilisersrs of the knee. The amount of tibial external rotation (the dial test) was measured for each knee before and after transection of the MCL. Results: The results of the dial test after transection of the MCL were similar to those stemming from a solitary injury to the posterolateral corner. There was a significant increase in external rotation of the knee in 308 and 908 of flexion. More over, external rotation in 308 was significantly greater than external rotation in 908 of knee flexion. Conclusions: Whenever suspecting a posterolateral complex injury, one has to carefully perform a valgus stress test in 08 and 308. Although the support of a clinical study is needed in order to make a definite conclusion, the dial test is probably not reliable in the presence of medial instability, and alternative diagnostic measures should be used. # 2006 Elsevier Ltd. All rights reserved.
* Corresponding author at: Department of Orthopaedic Surgery B’, Tel Aviv Sourasky Medical Center, 6 Weitzman St., Tel Aviv 64239, Israel. Tel.: +972 3 6974727; fax: +972 3 6074546. E-mail address: [email protected] (T. Pritsch). 0020–1383/$ — see front matter # 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2006.03.009
1012
T. Pritsch et al.
Introduction
Table 1 The mean results of the dial test before and after transecting the medial collateral ligament (MCL)
Injuries of the posterolateral corner of the knee are infrequent. They can cause severe disability due to both instability and articular cartilage degeneration. The dial test (posterolateral rotation test) is the usual element of the physical examination specific to the evaluation of posterolateral instability; it was shown to provide a good assessment of the extent of posterolateral knee damage.4,5,13 The dial test was first described by Gollehan et al.4 It can be performed with the patient in a prone or supine position. The thigh is stabilised and a rotational force is applied through the foot and ankle. The examiner then looks for the extent of external rotation of the tibial tuberosity, and compares it with the contralateral healthy knee: an increase of >108 in external rotation at 308 of knee flexion compared with the contralateral side indicates a posterolateral knee injury. The test is then repeated at 908 of knee flexion. Normally, in an isolated posterolateral knee injury, there is less external rotation of the tibia at 908 than at 308.10 Greater external rotation of the tibia at 908 is indicative of a combined posterior cruciate ligament (PCL) and posterolateral corner injury.4,5,13 During the past year, we encountered two patients who underwent posterolateral corner reconstruction and still complained of persistent instability. On physical examination, both patients had positive dial tests and valgus opening at 08 and 308 of knee flexion, consistent with grade 3 medial collateral ligament (MCL) tears. The anteroposterior stability was intact. Both patients were operated elsewhere, and we retrieved their medical records: the diagnosis of posterolateral corner injury was apparently based on a history of indirect trauma to the knee, complaints of instability and a positive dial test. The purpose of this study was to find out whether the results of the dial test in a grade 3 MCL tear are similar to those of an injury to the posterolateral corner of the knee.
Dial test
Materials and methods Both knees of seven fresh frozen cadavers of individuals with no medical record of knee surgery or instability were studied. The stability of each knee was first verified by applying the anterior drawer test, the Lachman test and a mediolateral stress at 08 and 308 of flexion. The dial test was then performed at 308 and 908 of knee flexion. It was carried out with the cadaver lying in a supine position and the examined knee flexed over the examination
MCL intact (n = 14) 308 Flexion 908 Flexion
Mean
8.358 8.428
MCL transected (n = 14) 308 Flexion 22.928 * 908 Flexion 19.868 * *
Standard deviation 1.277 1.398 3.26 1.96
p = 0.001 (Wilcoxon).
table. After stabilising the thigh, one examiner maximally externally rotated the leg while the other measured the amount of external rotation of the foot using a goniometer. Each measurement was taken three times and a mean was calculated. After examining the intact knees, the deep and superficial components of the MCL were cut, taking care not to dissect the posterior oblique ligament or the medial patellar reticulum. The dial test was then performed again at 308 and 908 of knee flexion using the same method for the measurements.
Statistics The Wilcoxon statistical test was used to analyse the results. A p value of <0.05 was considered significant.
Results The mean values for the dial test in the intact knees at 308 and 908 of flexion were 8.358 and 8.428, respectively. Cutting the MCL increased those values significantly (Table 1). The mean value of the dial test was 22.938 at 308 ( p = 0.0001) and 19.868 at 908 ( p = 0.0001). The differences between the results of the dial test at 308 and 908 of knee flexion, before and after transection of the MCL were also compared. After transecting the MCL, the external rotation of the tibia at 308 had increased by a mean value of 3.148 as compared to the external rotation at 908 ( p = 0.0006).
Discussion We carried out this study after having treated two cases of grade 3 MCL tears imitating posterolateral complex injury during the past year. Both patients described a typical mechanism of injury (indirect trauma), complaints of ‘‘giving way’’ and a positive dial test, and both underwent posterolateral recon-
Importance of the valgus stress test structions. They presented to our outpatient clinic due to continuous complaints of knee instability postoperatively. Recent reviews1,3,9 have considered the dial test to be almost pathognomonic for posterolateral complex injury. However, according to the results of this study, it is also positive in grade 3 MCL tears. Moreover, similar to the results of the dial test in an isolated posterolateral complex injury, the external rotation of the tibia at 908 of knee flexion was significantly less than at 308. Several biomechanical studies had found excessive external rotation of the tibia after transection of the MCL.8,11,14 However, most of them did not analyse their findings statistically and none looked at the difference in external rotation between 308 and 908 of knee flexion. Warren et al.14 performed a sequential transection of the MCL on cadaver knees and found an increase in tibial external rotation after transecting the long fibres. Kennedy and Fowler8 sectioned the deep portion of the medial collateral ligament in otherwise intact specimens. Although they noted instability, they did not record its extent. Matsumoto and Seedhom11 sectioned the MCL in three cadaveric knees and noted that external rotation was increased between flexion angles of 308 and 908 in two of the knees and throughout the range of flexion in the third knee. Haimes et al.6 measured the motion limits in human cadaveric knees before and after sectioning the anterior cruciate ligament (ACL) and the MCL. According to their results, cutting the MCL increased the external rotation limit, and the increase was independent of whether the ACL was intact. Hallen and Lindahl7 first sectioned the superficial portion of the MCL and then its deep portion and found a significant increase in total rotation of the tibia after sectioning the superficial part in an otherwise intact specimen. The results of our investigation are in agreement with the principle that compromise of the MCL leads to rotational instability of the tibia. A search of the English medical literature failed to uncover any mention of an MCL tear as part of the differential diagnosis of posterolateral instability, nor has it ever been recommended that a valgus stress test at 08 and 308 of knee flexion be performed after a dial test was found to be positive.1—3,9,10,12 Our findings demonstrated a statistically significant increase in the results of the dial test after transecting the deep and superficial part of the MCL as well as, a significant difference between 308 and 908 of knee flexion, thus mimicking an isolated injury to the posterolateral corner. An MCL tear probably causes excessive external rotation due to anterior translation of the medial tibial plateau,
1013 whereas posterolateral corner injury causes excessive external rotation due to subluxation of the lateral tibial plateau, however, the end result regarding the dial test is the same. We recognise that the amount of tibial rotation could have been determined more accurately by measuring the intermalleolar axis; however, the purpose of this study was to re-evaluate the Dial test, which is performed by external rotation of the foot. The advantage in a cadaveric study is the ability to create the exact injury that one wants to investigate. However, although measurements on cadaveric limbs are useful, they are somewhat different from the clinical scenario. The stability of the cadaveric knee relies only on the static stabilisers where as clinically, the surrounding muscles additionally contribute a very important dynamic stability. The results of this study should be supported by a clinical study before making definite conclusions, yet, according to our results, if medial instability compatible with a grade 3 MCL tear is diagnosed, the dial test might not be reliable, and alternative diagnostic tests for posterolateral instability should be used. We recommend performing a valgus stress test at 08 and 308 whenever a posterolateral complex injury is suspected. In addition, before undertaking a reconstructive procedure, it is recommended to perform magnetic resonance imaging of the knee, which can provide valuable evidence of MCL and posterolateral corner injury.
Acknowledgments We would like to thank the department of anatomy in Sackler Medical School, Tel Aviv University, for full cooperation and assistance. We would also like to thank Ms. Esther Eshkol for editorial assistance.
References 1. Chen FS, Rokito AS, Pitman MI. Acute and chronic posterolateral rotatory instability of the knee. J Am Acad Orthop Surg 2000;8:97—110. 2. Covey DC. Injuries of the posterolateral corner of the knee. J Bone Joint Surg A 2001;83:106—18. 3. Davies H, Unwin A, Aichroth P. The posterolateral corner of the knee. Anatomy, biomechanics and management of injuries. Injury 2004;35:68—75. 4. Gollehan DL, Torzilli PA, Waren RF. The role of the posterolateral and cruciate ligaments in the stability of the human knee: a biomechanical study. J Bone Joint Surg A 1987;69: 233—42. 5. Grood ES, Stowers SF, Noyes FR. Limits of movement in the human knee: effect of sectioning the posterior cruciate
1014
6.
7.
8.
9.
ligament and posterolateral structures. J Bone Joint Surg A 1988;70:88—97. Haimes JL, Wroble RR, Grood ES, Noyes FR. Role of the medial structures in the intact and anterior cruciate ligament-deficient knee. Limits of motion in the human knee. Am J Sports Med 1994;22:402—9. Hallen LG, Lindahl O. Rotation in the knee joint in experimental injury to the ligaments. Acta Orthop Scand 1965;36: 400—7. Kennedy JC, Fowler PJ. Medial and anterior instability of the knee. An anatomical and clinical study using stress machines. J Bone Joint Surg 1971;53A:1257—70. LaPrade RF, Wentorf FA. Diagnosis and treatment of posterolateral knee injuries. Clin Orthop 2002;402:110—21.
T. Pritsch et al. 10. Magee DJ, editor. Orthopedic Physical Assessment. Philadelphia: WB Sunders; 2002. 11. Matsumoto H, Seedhom BB. Rotation of the tibia in the normal and ligament-deficient knee. A study using biplanar photography. Proc Inst Mech Eng [H] 1993;207:175—84. 12. Miller III RH. Knee injuries. In: Canale ST, editor. Campbell’s Operative Orthopaedics. Philadelphia: Mosby; 2003. p. 2165—339. 13. Veltri DM, Deng XH, Torzilli PA, et al. The role of the cruciate and posterolateral ligaments in stability of the knee: a biomechanical study. Am J Sports Med 1995;23:436—43. 14. Warren LF, Marshall JL, Girgis F. The prime static stabilizer of the medial side of the knee. J Bone Joint Surg 1974;56A: 665—74.