REVIEW ARTICLE
Physical Examination and Imaging of Medial Collateral Ligament and Posteromedial Corner of the Knee Jason A. Craft, MD and Peter R. Kurzweil, MD
Abstract: The medial collateral ligament (MCL) is the most commonly injured knee ligament. Most will heal well with nonoperative treatment. However, not all medial knee injuries are the same. A detailed physical examination can help determine the severity of the medial-sided injury. When combined with advanced imaging, the examination will delineate damage to associated medial knee structures, including the location of MCL damage, posteromedial capsule injuries, and combined cruciate injuries. Failure to recognize MCL injuries that may be prone to chronic laxity can lead to significant disability, joint damage, and failure of concomitant cruciate ligament reconstructions. Magnetic resonance imaging is the mainstay of diagnostic imaging, with coronal sequences allowing full assessment of the MCL complex. Tangential views aid in the diagnosis of concomitant injuries. Stress radiography can play a role in evaluating MCL healing and subtle chronic laxity. Ultrasonography is also gaining acceptance as a means to assess MCL injuries. Use of a detailed examination and advanced imaging will allow optimal treatment of medial knee injuries and improve clinical outcomes. Key Words: medial collateral ligament, posteromedial capsule, posterior oblique ligament, magnetic resonance imaging, knee ligament injuries
(Sports Med Arthrosc Rev 2015;23:e1–e6)
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he recent literature on medial collateral ligament (MCL) injuries has focused on the need for medial knee reconstruction techniques.1–7 Although most cases of MCL injuries can still be managed nonoperatively with a good functional outcome,8–12 the reconstruction trend highlights the growing evidence that not all MCL injuries completely heal.10,13,14 Persistent laxity potentially leads to dysfunction, failure of cruciate reconstructions and meniscal repairs, and articular cartilage damage. It is evident that accurate diagnosis of medial knee injuries is imperative. The goal of this chapter is to highlight the physical examination techniques and imaging findings needed to diagnosis the full spectrum of MCL and medial capsular injuries and their potential associated injuries. When assessing the integrity of the medial knee restraints, it is important to understand the anatomic structures involved and their biomechanical roles.15–20 Robinson et al,16 in a very thorough cadaveric sectioning study, highlighted the roles of the 3 major static restraints to valgus rotation: (1) the superficial MCL (sMCL); (2) the deep MCL (dMCL); and (3) the posteromedial capsule (PMC). The thickening of the PMC is often referred to as From the Southern California Center for Sports Medicine, Long Beach, CA. Disclosure: The authors declare no conflict of interest. Reprints: Peter R. Kurzweil, MD, Southern California Center for Sports Medicine, Long Beach, CA. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
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the posterior oblique ligament. Though mainly functioning from 30 to 90 degrees, when intact, the sMCL is the main static stabilizer to valgus stress. The dMCL and PMC play secondary roles to an intact sMCL. However, when the sMCL is injured, the PMC plays the major role to valgus stability in extension and the dMCL functions as the main stabilizer in higher flexion angles. In addition to valgus control, deficient medial knee structures place 20% more load on the anterior cruciate ligament (ACL) when anterior translation stress is applied.16,21 The ACL is also an important secondary valgus stabilizer when the MCL is deficient. In an MCL-deficient knee, the ACL sees 185% increased load when valgus stress is applied.21 Chronic medial knee laxity, even when subtle, is a major risk for loss of stability after ACL reconstruction.22,23
PHYSICAL EXAMINATION Most athletes with MCL injuries will describe an impact to the lateral side of the knee while the foot is planted. This is a common mechanism in both football and soccer injuries. Patients may describe that the knee “popped” or “collapsed inward.” Some will complain of only pain with weight-bearing or a loss of motion due to pain; though others may feel the knee collapse or “wobble” with each step. Noncontact MCL injuries frequently occur while skiing, particularly with external tibial rotation applied to a flexed knee. The goal of the MCL examination is not just to appropriately diagnose the injury, but to also assess the grade of injury, location of injury, and associated injuries. The examination can be broken into 4 phases as follows: (1) observation of the knee and lower extremity as a whole; (2) palpation for areas of tenderness (injury); (3) ligament laxity testing; (4) evaluation of associated injuries. Although it may not always be possible, attempts should be made to evaluate patients while supine, standing, and during gait. In the acute setting, pain may make it impossible to evaluate the MCL in stance or during gait; however, it has been the author’s experience that those with neutral or varus alignment of the lower extremity are able to stand and ambulate more quickly than those with valgus alignment due to more medial knee stress with weightbearing in those with genu valgum. The location of swelling may be a clue to the zone of medial knee injury, whether at the femoral insertion (most common) or on the tibial side (more rare but prone to chronic laxity24,25). The presence of an effusion should warn the examiner to an associated intra-articular injury as MCL injures, in isolation, typically do not lead to an effusion. Medial skin dimpling can be the sign of an entrapped MCL or and irreducible knee dislocation.26 Palpation is the next important step in examination of the knee. Tenderness at the femoral or tibial insertion can www.sportsmedarthro.com |
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be a clue to the site of MCL injury. Femoral origin pain is most common. When there is tenderness at the tibial insertion with a feeling of subcutaneous fluctuance, there may be concern about a potential combined ligament or multiligamentous injury where a hemarthrosis has leaked through the dMCL/capsular tear. Mid-substance injuries typically elicit tenderness along the joint line. This location can make it difficult to distinguish between an MCL injury and a concomitant meniscus tear. Palpation of the lateral knee is also important. Tenderness of the lateral femoral condyle to tibial plateau may indicate bone bruises27 from a significant valgus injury. The lateral compression injury can also lead to lead to meniscal tears or chondral injuries. Laxity testing of the MCL complex is the mainstay of the physical examination diagnosis. In the acute phase, pain and muscle spasm make can make the examination difficult. It is important to have a strategy to mitigate these factors. Having the patient toward the edge of the examination table allows the examiner to have the thigh rest on the bed, which can relax the lower extremity. The foot drops slightly below the height of the bed while the knee is stressed (Fig. 1). Stress testing begins by applying a valgus force at 0 and 30 degrees while assessing the amount of ligament opening by keeping the examiner’s thumb at the joint line. Typical grading guidelines28 are as follows (AMA): grade 1 is 0 to 5 mm of opening with painful/firm endpoint, grade 2 is 5 to 10 mm with a firm endpoint, and grade 3 is >10 mm with a soft or absent endpoint. A more “functional” grading system is also useful29—still using valgus stress at 0 and 30 degrees as the examination. Begin by testing at 30 degrees, pain and minimal laxity is grade 1 (sMCL sprain). Next, laxity at 30 degrees but stable (even if painful) at 0 degrees is a grade 2 injury (sMCL torn, PMC intact). Finally, laxity at 30 and 0 degrees suggests complete injury to the sMCL and PMC—this is a grade 3 injury. Grade 3 injury in this grading system should raise concern for concomitant cruciate injury, and possibly the need for acute medial collateral repair. Hughston and Barrett30 popularized the idea of anteromedial rotatory instability (AMRI). AMRI is assessed by performing knee valgus stress at 30 degrees while holding the foot (instead of the tibia) with an external rotation force (Fig. 2). A positive test occurs when the knee opens with valgus (usually a grade 3 injury) and the medial tibial plateau also rotates forward in relation to the femur. Anatomically, this occurs because the PMC and MCL components are disrupted. The dMCL injury allows the tibia to rotate forward without the “chock-block” function of the medial meniscus preventing the anterior translation.31 Similar to the idea of AMRI is the testing done via the external rotation anterior drawer test. Increased medial plateau translation with anterior tibial stress while the knee is at 80 to 90 degrees of flexion and 15 degrees of external tibial rotation is positive for a dMCL injury. Finally, associated injuries must be assessed. Most importantly is the neurovascular status of the limb. Although most commonly associated with a grade 3 injury, any degree of MCL injury may be associated with a multiligamentous knee injury or knee dislocation—many of which spontaneously reduce. In this setting it is imperative to assess neurovascular status of the limb. The first step is documentation of the pedal pulses. If any question remains about vascular injury, a simple ankle-brachial index test should be considered. This compares upper and lower extremity blood pressures. An ankle brachial index of
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FIGURE 1. Valgus stress applied with the thigh supported by the bed to lessen pain and muscle guarding.
3.2 mm of laxity compared with the opposite knee at 20 degrees of flexion signifies a grade 3 injury and also leads to laxity in full extension. Combined MCL and cruciate injuries will show laxity approaching
FIGURE 3. Pelligrini-Steida lesion.
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9 mm or more. Stress imaging functions primarily to aid in the decision to repair/reconstruct the medial knee structures; when worry of chronic laxity could jeopardize cruciate ligament outcomes. Magnetic resonance imaging (MRI) is the mainstay of assessing the soft-tissue structures of the knee. MRI allows the best evaluation of the degree and location of MCL injury, and the amount of displacement of the ligament. The MRI also can evaluate for combined cruciate, meniscal, and chondral damage. When stress imaging is not possible, MRI also allows assessment of physeal damage by showing periphyseal edema and periosteal stripping (Fig. 5). Some cases of low-grade proximal MCL injuries are so painful that the knee appears “locked.” For these, MRI can rule out any locked meniscus or other entrapped soft tissue as the reason for minimal knee motion. In this author’s practice, MRI is not indicated for grade 1 and 2 injuries that are without concern for associated injuries. An MRI would be ordered for grade 1 and 2 injuries with an effusion, suspected cruciate, or patellar instability or lateral joint line pain. For grade 3 injuries, laxity at 0 degrees of extension, an MRI should be ordered to evaluate other likely concomitant injuries and for possible surgical planning. The MCL is best assessed on the coronal MRI images, using T-1 and T-2 sequences, where it can be seen in continuity from the medial epicondyle to its insertion of 4 to 6 cm below the joint line (Fig. 6). Axial plane images can show edema and swelling along the posteromedial corner and suggest injury to the dMCL and PMC components. Sagittal plane images also allow evaluation of the posterior meniscofemoral and meniscotibial ligament attachments (Fig. 7). These sagittal and axial images also allow evaluation of surrounding structures of the posteromedial corner which can be injured in high-grade injuries, including the variable attachments of the semimembranosus tendon and the attachment of the medial head of the gactrocnemius muscle.30,31 Grading of the MCL on MRI is possible,41 although its correlation with clinical laxity grading is suspect.42 MRI grade I being ligament swelling and edema, partial tearing with all structures overall intact. MRI grade II will show tearing of some medial structures with others intact; for instance, the sMCL is torn with dMCL intact, or vice versa (Fig. 7). MRI grade III shows complete disruption of the superficial and deep layers. There can be significant softtissue fluid and edema with grade III lesions as intraarticular fluid can leak from the knee through the capsular tears. Hayes et al43 devised a mechanism-based classification of knee injuries. They used bone bruises and other signs as a clue to the direction of force applied to the knee. From this, there were better able to identify posteromedial corner and other associated injuries. MRI can also suggest which medial-sided knee injuries should be considered for repair. Injuries with medial structures entrapped in the knee (usually dMCL) should be surgically repaired. Nakamura et al44 studied the healing of grade III MCL injuries with combined ACL tears. After 6 weeks of bracing, patients underwent stress imaging at the time of, but before, ACL reconstruction. This is important as ACL reconstruction restores a secondary valgus stabilizer and will lead to underappreciation of residual MCL deficiency. Five of 17 patients had laxity that required MCL reconstruction with ACL reconstruction. These 5 patients who had MRI showed diffuse edema through sMCL, with
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FIGURE 4. Positive stress test for persistent medial collateral ligament laxity after ACL reconstruction. A, Stress view of normal knee. B, Stress view showing chronic MCL laxity.
minimal normal ligament seen on coronal MR images. This study suggests that these diffuse injuries may not heal with adequate stability by 6 weeks and should raise concern for
the need for combined ACL/MCL reconstruction. Also, MRI allows evaluation of the degree of displacement of distal MCL injuries. The tibial attachment may have less
FIGURE 5. Magnetic resonance imaging of proximal tibial physeal injury with entrapped superficial medial collateral ligament.
FIGURE 6. Normal coronal magnetic resonance imaging showing medial collateral ligament in continuity.
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Physical Examination and Imaging of MCL
fractures due to valgus stress. It also may aid in the diagnosis and surgical planning of suspected symptomatic Pelligrini-Steida lesions. Ultrasound has gained momentum as an alternative to soft-tissue injury diagnosis around the knee.45–48 There is also some renewed interest in ultrasound evaluation of MCL injuries, especially as ultrasound machines become more affordable and available. In 1 study,45 the use of ultrasound was able to predict the injury location and severity in 94% of patients. Another46 reported success in diagnosing acute or chronic medial knee laxity compared with a normal knee control group using applied stress combined with ultrasonography. Limitations of this modality continue to be technical, with most orthopedists having limited experience or training in using ultrasound for diagnosing knee injuries.
CONCLUSIONS
FIGURE 7. Deep medial collateral ligament (MCL) torn and superficial MCL intact.
healing capability than the femoral origin due to the overall environment. However, the increased displacement of injuries here also leads to poor healing ability.24 Most concerning is the MCL “Stener” lesion (Fig. 8) where the sMCL tears at its distal insertion and is able to pull proximal and displace anterior to the pes anserine tendons, which then block reduction. This distal injury requires repair. Computed tomography has a role in evaluating bony ligament avulsion from the medial epicondyle. Computed tomography is also the imaging of choice to evaluate amount of displacement of any lateral tibial plateau
FIGURE 8. Medial collateral ligament “Stener” lesion with superficial torn distally and displace anterior to the hamstring tendon attachment.
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MCL injuries are common, and most will heal well with conservative measures. However, prolonged disability can occur when the MCL complex does not fully heal and chronic valgus laxity persists. Unrecognized chronic laxity can lead to symptomatic knee instability, failed cruciate reconstructions, and progressive meniscal and/or articular cartilage damage. This article has attempted to highlight the variability of medial knee injuries and aid in their accurate diagnosis—they are not all the same. A thorough history, complete physical examination, and advanced imaging give the physician the needed information to evaluate and treat each medial knee injury appropriately. REFERENCES 1. Laprade RF, Wijdicks CA. Surgical technique: development of an anatomic medial knee reconstruction. Clin Orthop Relat Res. 2012;470:806–814. 2. Lind M, Jakobsen BW, Lund B, et al. Anatomical reconstruction of the medial collateral ligament and posteromedial corner of the knee in patients with chronic medial collateral ligament instability. Am J Sports Med. 2009;37:1116–1122. 3. Coobs BR, Wijdicks CA, Armitage BM, et al. An in vitro analysis of an anatomical medial knee reconstruction. Am J Sports Med. 2010;38:339–347. 4. Zhang H, Sun Y, Han X, et al. Simultaneous reconstruction of the anterior cruciate ligament and medial collateral ligament in patients with chronic ACL-MCL lesions: a minimum 2-year follow-up study. Am J Sports Med. 2014;42:1675–1681. 5. Wijdicks CA, Michalski MP, Rasmussen MT, et al. Superficial medial collateral ligament anatomic augmented repair versus anatomic reconstruction: an in vitro biomechanical analysis. Am J Sports Med. 2013;41:2858–2866. 6. Liu X, Feng H, Zhang H, et al. Surgical treatment of subacute and chronic valgus instability in multiligament-injured knees with superficial medial collateral ligament reconstruction using Achilles allografts: a quantitative analysis with a minimum 2-year follow-up. Am J Sports Med. 2013;41:1044–1050. 7. Stannard JP, Black BS, Azbell C, et al. Posteromedial corner injury in knee dislocations. J Knee Surg. 2012;25:429–434. 8. Indelicato PA. Non-operative treatment of complete tears of the medial collateral ligament of the knee. J Bone Joint Surg Am. 1983;65:323–329. 9. Indelicato PA. Isolated medial collateral ligament injuries in the knee. J Am Acad Orthop Surg. 1995;3:9–14. 10. Reider B, Sathy MR, Talkington J, et al. Treatment of isolated medial collateral ligament injuries in athletes with early functional rehabilitation. A five-year follow-up study. Am J Sports Med. 1994;22:470–477.
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11. Ballmer PM, Jakob RP. The non operative treatment of isolated complete tears of the medial collateral ligament of the knee. A prospective study. Arch Orthop Trauma Surg. 1988; 107:273–276. 12. Ellsasser JC, Reynolds FC, Omohundro JR. The nonoperative treatment of collateral ligament injuries of the knee in professional football players. An analysis of seventy-four injuries treated non-operatively and twenty-four injuries treated surgically. J Bone Joint Surg Am. 1974;56:1185–1190. 13. Kannus P. Long-term results of conservatively treated medial collateral ligament injuries of the knee joint. Clin Orthop Relat Res. 1988;226:103–112. 14. Frank CB, Loitz BJ, Shrive NG. Injury location affects ligament healing. A morphologic and mechanical study of the healing rabbit medial collateral ligament. Acta Orthop Scand. 1995;66:455–462. 15. Robinson JR, Bull AM, Amis AA. Structural properties of the medial collateral ligament complex of the human knee. J Biomech. 2005;38:1067–1074. 16. Robinson JR, Bull AM, Thomas RR, et al. The role of the medial collateral ligament and posteromedial capsule in controlling knee laxity. Am J Sports Med. 2006;34:1815–1823. 17. Grood ES, Noyes FR, Butler DL, et al. Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg Am. 1981;63:1257–1269. 18. Jacobson KE, Chi FS. Evaluation and treatment of medial collateral ligament and medial-sided injuries of the knee. Sports Med Arthrosc. 2006;14:58–66. 19. Marchant MH Jr, Tibor LM, Sekiya JK, et al. Management of medial-sided knee injuries, part 1: medial collateral ligament. Am J Sports Med. 2011;39:1102–1113. 20. Wijdicks CA, Swenson TM, Irrgang JJ, et al. Medial knee injury: Part 2, load sharing between the posterior oblique ligament and superficial medial collateral ligament. Am J Sports Med. 2009;37:1771–1776. 21. Battaglia MJ II, Lenhoff MW, Ehteshami JR, et al. Medial collateral ligament injuries and subsequent load on the anterior cruciate ligament: a biomechanical evaluation in a cadaveric model. Am J Sports Med. 2009;37:305–311. 22. Johnson DL, Swenson TM, Irrgang JJ, et al. Revision anterior cruciate ligament surgery: experience from Pittsburgh. Clin Orthop Relat Res. 1996;325:100–109. 23. Getelman MH, Friedman MJ. Revision anterior cruciate ligament reconstruction surgery. J Am Acad Orthop Surg. 1999;7:189–198. 24. Wilson TC, Satterfield WH, Johnson DL. Medial collateral ligament “tibial” injuries: indication for acute repair. Orthopedics. 2004;27:389–393. 25. Bollier M, Smith PA. Anterior cruciate ligament and medial collateral ligament injuries. J Knee Surg. 2014;27:359–368. 26. Braun DT, Muffly MT, Altman GT. Irreducible posterolateral knee dislocation with entrapment of the adductor magnus tendon and medial skin dimpling. J Knee Surg. 2009;22:366–369. 27. Miller MD, Osborne JR, Gordon WT, et al. The natural history of bone bruises. A prospective study of magnetic resonance imaging-detected trabecular microfractures in patients with isolated medial collateral ligament injuries. Am J Sports Med. 1998;26:15–19. 28. Injuries, American Medical Association. Committee on the Medical Aspects of Sports. Subcommittee on Classification of Sports Injuries in Standard Nomenclature for Athletic Injuries. 1966, A.M.A. p. 99-100. 29. Fetto JF, Marshall JL. Medial collateral ligament injuries of the knee: a rationale for treatment. Clin Orthop Relat Res. 1978;132:206–218.
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30. Hughston JC, Barrett GR. Acute anteromedial rotatory instability. Long-term results of surgical repair. J Bone Joint Surg Am. 1983;65:145–153. 31. Sims WF, Jacobson KE. The posteromedial corner of the knee: medial-sided injury patterns revisited. Am J Sports Med. 2004; 32:337–345. 32. Mills WJ, Barei DP, McNair P. The value of the ankle-brachial index for diagnosing arterial injury after knee dislocation: a prospective study. J Trauma. 2004;56:1261–1265. 33. Guerrero P, Li X, Patel K, et al. Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: an MRI study. Sports Med Arthrosc Rehabil Ther Technol. 2009;1:17. 34. Quinlan JF, Farrelly C, Kelly G, et al. Co-existent medial collateral ligament injury seen following transient patellar dislocation: observations at magnetic resonance imaging. Br J Sports Med. 2010;44:411–414. 35. Altschuler EL, Bryce TN. Images in clinical medicine. Pellegrini-Stieda syndrome. N Engl J Med. 2006;354:e1. 36. Muschol M, Muller I, Petersen W, et al. Symptomatic calcification of the medial collateral ligament of the knee joint: a report about five cases. Knee Surg Sports Traumatol Arthrosc. 2005;13:598–602. 37. Phisitkul P, Wolf BR, Amendola A. Role of high tibial and distal femoral osteotomies in the treatment of lateral-posterolateral and medial instabilities of the knee. Sports Med Arthrosc. 2006;14:96–104. 38. James EW, Williams BT, LaPrade RF. Stress radiography for the diagnosis of knee ligament injuries: a systematic review. Clin Orthop Relat Res. 2014;472:2644–2657. 39. Laprade RF, Bernhardson AS, Griffith CJ, et al. Correlation of valgus stress radiographs with medial knee ligament injuries: an in vitro biomechanical study. Am J Sports Med. 2010;38: 330–338. 40. Sawant M, Narasimha Murty A, Ireland J. Valgus knee injuries: evaluation and documentation using a simple technique of stress radiography. Knee. 2004;11:25–28. 41. Khanna AJ, Cosgarea AJ, Mont MA, et al. Magnetic resonance imaging of the knee. Current techniques and spectrum of disease. J Bone Joint Surg Am. 2001;83-A(suppl 2 pt 2):128–141. 42. Schweitzer ME, Tran D, Deely DM, et al. Medial collateral ligament injuries: evaluation of multiple signs, prevalence and location of associated bone bruises, and assessment with MR imaging. Radiology. 1995;194:825–829. 43. Hayes CW, Brigido MK, Jamadar DA, et al. Mechanismbased pattern approach to classification of complex injuries of the knee depicted at MR imaging. Radiographics. 2000;20: S121–S134. 44. Nakamura N, Horibe S, Toritsuka Y, et al. Acute grade III medial collateral ligament injury of the knee associated with anterior cruciate ligament tear. The usefulness of magnetic resonance imaging in determining a treatment regimen. Am J Sports Med. 2003;31:261–267. 45. Lee JI, Song IS, Jung YB, et al. Medial collateral ligament injuries of the knee: ultrasonographic findings. J Ultrasound Med. 1996;15:621–625. 46. Gruber G, Martens D, Konermann W. Value of ultrasound examination in lesion of the medial collateral ligament of the knee joint. Z Orthop Ihre Grenzgeb. 1998;136:337–342. 47. De Maeseneer M, Vanderdood K, Marcelis S, et al. Sonography of the medial and lateral tendons and ligaments of the knee: the use of bony landmarks as an easy method for identification. AJR Am J Roentgenol. 2002;178:1437–1444. 48. De Maeseneer M. Medial and lateral capsular and supporting structures of the knee: MR imaging and sonography with anatomic correlation. JBR-BTR. 2001;84:171–172.
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2015 Wolters Kluwer Health, Inc. All rights reserved.
Physical Examination and Imaging of Medial Collateral Ligament and Posteromedial Corner of the Knee Jason A. Craft, MD and Peter R. Kurzweil, MD
Abstract: The medial collateral ligament (MCL) is the most commonly injured knee ligament. Most will heal well with nonoperative treatment. However, not all medial knee injuries are the same. A detailed physical examination can help determine the severity of the medial-sided injury. When combined with advanced imaging, the examination will delineate damage to associated medial knee structures, including the location of MCL damage, posteromedial capsule injuries, and combined cruciate injuries. Failure to recognize MCL injuries that may be prone to chronic laxity can lead to significant disability, joint damage, and failure of concomitant cruciate ligament reconstructions. Magnetic resonance imaging is the mainstay of diagnostic imaging, with coronal sequences allowing full assessment of the MCL complex. Tangential views aid in the diagnosis of concomitant injuries. Stress radiography can play a role in evaluating MCL healing and subtle chronic laxity. Ultrasonography is also gaining acceptance as a means to assess MCL injuries. Use of a detailed examination and advanced imaging will allow optimal treatment of medial knee injuries and improve clinical outcomes. Key Words: medial collateral ligament, posteromedial capsule, posterior oblique ligament, magnetic resonance imaging, knee ligament injuries
(Sports Med Arthrosc Rev 2015;23:e1–e6)
T
he recent literature on medial collateral ligament (MCL) injuries has focused on the need for medial knee reconstruction techniques.1–7 Although most cases of MCL injuries can still be managed nonoperatively with a good functional outcome,8–12 the reconstruction trend highlights the growing evidence that not all MCL injuries completely heal.10,13,14 Persistent laxity potentially leads to dysfunction, failure of cruciate reconstructions and meniscal repairs, and articular cartilage damage. It is evident that accurate diagnosis of medial knee injuries is imperative. The goal of this chapter is to highlight the physical examination techniques and imaging findings needed to diagnosis the full spectrum of MCL and medial capsular injuries and their potential associated injuries. When assessing the integrity of the medial knee restraints, it is important to understand the anatomic structures involved and their biomechanical roles.15–20 Robinson et al,16 in a very thorough cadaveric sectioning study, highlighted the roles of the 3 major static restraints to valgus rotation: (1) the superficial MCL (sMCL); (2) the deep MCL (dMCL); and (3) the posteromedial capsule (PMC). The thickening of the PMC is often referred to as From the Southern California Center for Sports Medicine, Long Beach, CA. Disclosure: The authors declare no conflict of interest. Reprints: Peter R. Kurzweil, MD, Southern California Center for Sports Medicine, Long Beach, CA. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved.
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the posterior oblique ligament. Though mainly functioning from 30 to 90 degrees, when intact, the sMCL is the main static stabilizer to valgus stress. The dMCL and PMC play secondary roles to an intact sMCL. However, when the sMCL is injured, the PMC plays the major role to valgus stability in extension and the dMCL functions as the main stabilizer in higher flexion angles. In addition to valgus control, deficient medial knee structures place 20% more load on the anterior cruciate ligament (ACL) when anterior translation stress is applied.16,21 The ACL is also an important secondary valgus stabilizer when the MCL is deficient. In an MCL-deficient knee, the ACL sees 185% increased load when valgus stress is applied.21 Chronic medial knee laxity, even when subtle, is a major risk for loss of stability after ACL reconstruction.22,23
PHYSICAL EXAMINATION Most athletes with MCL injuries will describe an impact to the lateral side of the knee while the foot is planted. This is a common mechanism in both football and soccer injuries. Patients may describe that the knee “popped” or “collapsed inward.” Some will complain of only pain with weight-bearing or a loss of motion due to pain; though others may feel the knee collapse or “wobble” with each step. Noncontact MCL injuries frequently occur while skiing, particularly with external tibial rotation applied to a flexed knee. The goal of the MCL examination is not just to appropriately diagnose the injury, but to also assess the grade of injury, location of injury, and associated injuries. The examination can be broken into 4 phases as follows: (1) observation of the knee and lower extremity as a whole; (2) palpation for areas of tenderness (injury); (3) ligament laxity testing; (4) evaluation of associated injuries. Although it may not always be possible, attempts should be made to evaluate patients while supine, standing, and during gait. In the acute setting, pain may make it impossible to evaluate the MCL in stance or during gait; however, it has been the author’s experience that those with neutral or varus alignment of the lower extremity are able to stand and ambulate more quickly than those with valgus alignment due to more medial knee stress with weightbearing in those with genu valgum. The location of swelling may be a clue to the zone of medial knee injury, whether at the femoral insertion (most common) or on the tibial side (more rare but prone to chronic laxity24,25). The presence of an effusion should warn the examiner to an associated intra-articular injury as MCL injures, in isolation, typically do not lead to an effusion. Medial skin dimpling can be the sign of an entrapped MCL or and irreducible knee dislocation.26 Palpation is the next important step in examination of the knee. Tenderness at the femoral or tibial insertion can www.sportsmedarthro.com |
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be a clue to the site of MCL injury. Femoral origin pain is most common. When there is tenderness at the tibial insertion with a feeling of subcutaneous fluctuance, there may be concern about a potential combined ligament or multiligamentous injury where a hemarthrosis has leaked through the dMCL/capsular tear. Mid-substance injuries typically elicit tenderness along the joint line. This location can make it difficult to distinguish between an MCL injury and a concomitant meniscus tear. Palpation of the lateral knee is also important. Tenderness of the lateral femoral condyle to tibial plateau may indicate bone bruises27 from a significant valgus injury. The lateral compression injury can also lead to lead to meniscal tears or chondral injuries. Laxity testing of the MCL complex is the mainstay of the physical examination diagnosis. In the acute phase, pain and muscle spasm make can make the examination difficult. It is important to have a strategy to mitigate these factors. Having the patient toward the edge of the examination table allows the examiner to have the thigh rest on the bed, which can relax the lower extremity. The foot drops slightly below the height of the bed while the knee is stressed (Fig. 1). Stress testing begins by applying a valgus force at 0 and 30 degrees while assessing the amount of ligament opening by keeping the examiner’s thumb at the joint line. Typical grading guidelines28 are as follows (AMA): grade 1 is 0 to 5 mm of opening with painful/firm endpoint, grade 2 is 5 to 10 mm with a firm endpoint, and grade 3 is >10 mm with a soft or absent endpoint. A more “functional” grading system is also useful29—still using valgus stress at 0 and 30 degrees as the examination. Begin by testing at 30 degrees, pain and minimal laxity is grade 1 (sMCL sprain). Next, laxity at 30 degrees but stable (even if painful) at 0 degrees is a grade 2 injury (sMCL torn, PMC intact). Finally, laxity at 30 and 0 degrees suggests complete injury to the sMCL and PMC—this is a grade 3 injury. Grade 3 injury in this grading system should raise concern for concomitant cruciate injury, and possibly the need for acute medial collateral repair. Hughston and Barrett30 popularized the idea of anteromedial rotatory instability (AMRI). AMRI is assessed by performing knee valgus stress at 30 degrees while holding the foot (instead of the tibia) with an external rotation force (Fig. 2). A positive test occurs when the knee opens with valgus (usually a grade 3 injury) and the medial tibial plateau also rotates forward in relation to the femur. Anatomically, this occurs because the PMC and MCL components are disrupted. The dMCL injury allows the tibia to rotate forward without the “chock-block” function of the medial meniscus preventing the anterior translation.31 Similar to the idea of AMRI is the testing done via the external rotation anterior drawer test. Increased medial plateau translation with anterior tibial stress while the knee is at 80 to 90 degrees of flexion and 15 degrees of external tibial rotation is positive for a dMCL injury. Finally, associated injuries must be assessed. Most importantly is the neurovascular status of the limb. Although most commonly associated with a grade 3 injury, any degree of MCL injury may be associated with a multiligamentous knee injury or knee dislocation—many of which spontaneously reduce. In this setting it is imperative to assess neurovascular status of the limb. The first step is documentation of the pedal pulses. If any question remains about vascular injury, a simple ankle-brachial index test should be considered. This compares upper and lower extremity blood pressures. An ankle brachial index of
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FIGURE 1. Valgus stress applied with the thigh supported by the bed to lessen pain and muscle guarding.
3.2 mm of laxity compared with the opposite knee at 20 degrees of flexion signifies a grade 3 injury and also leads to laxity in full extension. Combined MCL and cruciate injuries will show laxity approaching
FIGURE 3. Pelligrini-Steida lesion.
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9 mm or more. Stress imaging functions primarily to aid in the decision to repair/reconstruct the medial knee structures; when worry of chronic laxity could jeopardize cruciate ligament outcomes. Magnetic resonance imaging (MRI) is the mainstay of assessing the soft-tissue structures of the knee. MRI allows the best evaluation of the degree and location of MCL injury, and the amount of displacement of the ligament. The MRI also can evaluate for combined cruciate, meniscal, and chondral damage. When stress imaging is not possible, MRI also allows assessment of physeal damage by showing periphyseal edema and periosteal stripping (Fig. 5). Some cases of low-grade proximal MCL injuries are so painful that the knee appears “locked.” For these, MRI can rule out any locked meniscus or other entrapped soft tissue as the reason for minimal knee motion. In this author’s practice, MRI is not indicated for grade 1 and 2 injuries that are without concern for associated injuries. An MRI would be ordered for grade 1 and 2 injuries with an effusion, suspected cruciate, or patellar instability or lateral joint line pain. For grade 3 injuries, laxity at 0 degrees of extension, an MRI should be ordered to evaluate other likely concomitant injuries and for possible surgical planning. The MCL is best assessed on the coronal MRI images, using T-1 and T-2 sequences, where it can be seen in continuity from the medial epicondyle to its insertion of 4 to 6 cm below the joint line (Fig. 6). Axial plane images can show edema and swelling along the posteromedial corner and suggest injury to the dMCL and PMC components. Sagittal plane images also allow evaluation of the posterior meniscofemoral and meniscotibial ligament attachments (Fig. 7). These sagittal and axial images also allow evaluation of surrounding structures of the posteromedial corner which can be injured in high-grade injuries, including the variable attachments of the semimembranosus tendon and the attachment of the medial head of the gactrocnemius muscle.30,31 Grading of the MCL on MRI is possible,41 although its correlation with clinical laxity grading is suspect.42 MRI grade I being ligament swelling and edema, partial tearing with all structures overall intact. MRI grade II will show tearing of some medial structures with others intact; for instance, the sMCL is torn with dMCL intact, or vice versa (Fig. 7). MRI grade III shows complete disruption of the superficial and deep layers. There can be significant softtissue fluid and edema with grade III lesions as intraarticular fluid can leak from the knee through the capsular tears. Hayes et al43 devised a mechanism-based classification of knee injuries. They used bone bruises and other signs as a clue to the direction of force applied to the knee. From this, there were better able to identify posteromedial corner and other associated injuries. MRI can also suggest which medial-sided knee injuries should be considered for repair. Injuries with medial structures entrapped in the knee (usually dMCL) should be surgically repaired. Nakamura et al44 studied the healing of grade III MCL injuries with combined ACL tears. After 6 weeks of bracing, patients underwent stress imaging at the time of, but before, ACL reconstruction. This is important as ACL reconstruction restores a secondary valgus stabilizer and will lead to underappreciation of residual MCL deficiency. Five of 17 patients had laxity that required MCL reconstruction with ACL reconstruction. These 5 patients who had MRI showed diffuse edema through sMCL, with
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FIGURE 4. Positive stress test for persistent medial collateral ligament laxity after ACL reconstruction. A, Stress view of normal knee. B, Stress view showing chronic MCL laxity.
minimal normal ligament seen on coronal MR images. This study suggests that these diffuse injuries may not heal with adequate stability by 6 weeks and should raise concern for
the need for combined ACL/MCL reconstruction. Also, MRI allows evaluation of the degree of displacement of distal MCL injuries. The tibial attachment may have less
FIGURE 5. Magnetic resonance imaging of proximal tibial physeal injury with entrapped superficial medial collateral ligament.
FIGURE 6. Normal coronal magnetic resonance imaging showing medial collateral ligament in continuity.
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Physical Examination and Imaging of MCL
fractures due to valgus stress. It also may aid in the diagnosis and surgical planning of suspected symptomatic Pelligrini-Steida lesions. Ultrasound has gained momentum as an alternative to soft-tissue injury diagnosis around the knee.45–48 There is also some renewed interest in ultrasound evaluation of MCL injuries, especially as ultrasound machines become more affordable and available. In 1 study,45 the use of ultrasound was able to predict the injury location and severity in 94% of patients. Another46 reported success in diagnosing acute or chronic medial knee laxity compared with a normal knee control group using applied stress combined with ultrasonography. Limitations of this modality continue to be technical, with most orthopedists having limited experience or training in using ultrasound for diagnosing knee injuries.
CONCLUSIONS
FIGURE 7. Deep medial collateral ligament (MCL) torn and superficial MCL intact.
healing capability than the femoral origin due to the overall environment. However, the increased displacement of injuries here also leads to poor healing ability.24 Most concerning is the MCL “Stener” lesion (Fig. 8) where the sMCL tears at its distal insertion and is able to pull proximal and displace anterior to the pes anserine tendons, which then block reduction. This distal injury requires repair. Computed tomography has a role in evaluating bony ligament avulsion from the medial epicondyle. Computed tomography is also the imaging of choice to evaluate amount of displacement of any lateral tibial plateau
FIGURE 8. Medial collateral ligament “Stener” lesion with superficial torn distally and displace anterior to the hamstring tendon attachment.
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MCL injuries are common, and most will heal well with conservative measures. However, prolonged disability can occur when the MCL complex does not fully heal and chronic valgus laxity persists. Unrecognized chronic laxity can lead to symptomatic knee instability, failed cruciate reconstructions, and progressive meniscal and/or articular cartilage damage. This article has attempted to highlight the variability of medial knee injuries and aid in their accurate diagnosis—they are not all the same. A thorough history, complete physical examination, and advanced imaging give the physician the needed information to evaluate and treat each medial knee injury appropriately. REFERENCES 1. Laprade RF, Wijdicks CA. Surgical technique: development of an anatomic medial knee reconstruction. Clin Orthop Relat Res. 2012;470:806–814. 2. Lind M, Jakobsen BW, Lund B, et al. Anatomical reconstruction of the medial collateral ligament and posteromedial corner of the knee in patients with chronic medial collateral ligament instability. Am J Sports Med. 2009;37:1116–1122. 3. Coobs BR, Wijdicks CA, Armitage BM, et al. An in vitro analysis of an anatomical medial knee reconstruction. Am J Sports Med. 2010;38:339–347. 4. Zhang H, Sun Y, Han X, et al. Simultaneous reconstruction of the anterior cruciate ligament and medial collateral ligament in patients with chronic ACL-MCL lesions: a minimum 2-year follow-up study. Am J Sports Med. 2014;42:1675–1681. 5. Wijdicks CA, Michalski MP, Rasmussen MT, et al. Superficial medial collateral ligament anatomic augmented repair versus anatomic reconstruction: an in vitro biomechanical analysis. Am J Sports Med. 2013;41:2858–2866. 6. Liu X, Feng H, Zhang H, et al. Surgical treatment of subacute and chronic valgus instability in multiligament-injured knees with superficial medial collateral ligament reconstruction using Achilles allografts: a quantitative analysis with a minimum 2-year follow-up. Am J Sports Med. 2013;41:1044–1050. 7. Stannard JP, Black BS, Azbell C, et al. Posteromedial corner injury in knee dislocations. J Knee Surg. 2012;25:429–434. 8. Indelicato PA. Non-operative treatment of complete tears of the medial collateral ligament of the knee. J Bone Joint Surg Am. 1983;65:323–329. 9. Indelicato PA. Isolated medial collateral ligament injuries in the knee. J Am Acad Orthop Surg. 1995;3:9–14. 10. Reider B, Sathy MR, Talkington J, et al. Treatment of isolated medial collateral ligament injuries in athletes with early functional rehabilitation. A five-year follow-up study. Am J Sports Med. 1994;22:470–477.
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11. Ballmer PM, Jakob RP. The non operative treatment of isolated complete tears of the medial collateral ligament of the knee. A prospective study. Arch Orthop Trauma Surg. 1988; 107:273–276. 12. Ellsasser JC, Reynolds FC, Omohundro JR. The nonoperative treatment of collateral ligament injuries of the knee in professional football players. An analysis of seventy-four injuries treated non-operatively and twenty-four injuries treated surgically. J Bone Joint Surg Am. 1974;56:1185–1190. 13. Kannus P. Long-term results of conservatively treated medial collateral ligament injuries of the knee joint. Clin Orthop Relat Res. 1988;226:103–112. 14. Frank CB, Loitz BJ, Shrive NG. Injury location affects ligament healing. A morphologic and mechanical study of the healing rabbit medial collateral ligament. Acta Orthop Scand. 1995;66:455–462. 15. Robinson JR, Bull AM, Amis AA. Structural properties of the medial collateral ligament complex of the human knee. J Biomech. 2005;38:1067–1074. 16. Robinson JR, Bull AM, Thomas RR, et al. The role of the medial collateral ligament and posteromedial capsule in controlling knee laxity. Am J Sports Med. 2006;34:1815–1823. 17. Grood ES, Noyes FR, Butler DL, et al. Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg Am. 1981;63:1257–1269. 18. Jacobson KE, Chi FS. Evaluation and treatment of medial collateral ligament and medial-sided injuries of the knee. Sports Med Arthrosc. 2006;14:58–66. 19. Marchant MH Jr, Tibor LM, Sekiya JK, et al. Management of medial-sided knee injuries, part 1: medial collateral ligament. Am J Sports Med. 2011;39:1102–1113. 20. Wijdicks CA, Swenson TM, Irrgang JJ, et al. Medial knee injury: Part 2, load sharing between the posterior oblique ligament and superficial medial collateral ligament. Am J Sports Med. 2009;37:1771–1776. 21. Battaglia MJ II, Lenhoff MW, Ehteshami JR, et al. Medial collateral ligament injuries and subsequent load on the anterior cruciate ligament: a biomechanical evaluation in a cadaveric model. Am J Sports Med. 2009;37:305–311. 22. Johnson DL, Swenson TM, Irrgang JJ, et al. Revision anterior cruciate ligament surgery: experience from Pittsburgh. Clin Orthop Relat Res. 1996;325:100–109. 23. Getelman MH, Friedman MJ. Revision anterior cruciate ligament reconstruction surgery. J Am Acad Orthop Surg. 1999;7:189–198. 24. Wilson TC, Satterfield WH, Johnson DL. Medial collateral ligament “tibial” injuries: indication for acute repair. Orthopedics. 2004;27:389–393. 25. Bollier M, Smith PA. Anterior cruciate ligament and medial collateral ligament injuries. J Knee Surg. 2014;27:359–368. 26. Braun DT, Muffly MT, Altman GT. Irreducible posterolateral knee dislocation with entrapment of the adductor magnus tendon and medial skin dimpling. J Knee Surg. 2009;22:366–369. 27. Miller MD, Osborne JR, Gordon WT, et al. The natural history of bone bruises. A prospective study of magnetic resonance imaging-detected trabecular microfractures in patients with isolated medial collateral ligament injuries. Am J Sports Med. 1998;26:15–19. 28. Injuries, American Medical Association. Committee on the Medical Aspects of Sports. Subcommittee on Classification of Sports Injuries in Standard Nomenclature for Athletic Injuries. 1966, A.M.A. p. 99-100. 29. Fetto JF, Marshall JL. Medial collateral ligament injuries of the knee: a rationale for treatment. Clin Orthop Relat Res. 1978;132:206–218.
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30. Hughston JC, Barrett GR. Acute anteromedial rotatory instability. Long-term results of surgical repair. J Bone Joint Surg Am. 1983;65:145–153. 31. Sims WF, Jacobson KE. The posteromedial corner of the knee: medial-sided injury patterns revisited. Am J Sports Med. 2004; 32:337–345. 32. Mills WJ, Barei DP, McNair P. The value of the ankle-brachial index for diagnosing arterial injury after knee dislocation: a prospective study. J Trauma. 2004;56:1261–1265. 33. Guerrero P, Li X, Patel K, et al. Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: an MRI study. Sports Med Arthrosc Rehabil Ther Technol. 2009;1:17. 34. Quinlan JF, Farrelly C, Kelly G, et al. Co-existent medial collateral ligament injury seen following transient patellar dislocation: observations at magnetic resonance imaging. Br J Sports Med. 2010;44:411–414. 35. Altschuler EL, Bryce TN. Images in clinical medicine. Pellegrini-Stieda syndrome. N Engl J Med. 2006;354:e1. 36. Muschol M, Muller I, Petersen W, et al. Symptomatic calcification of the medial collateral ligament of the knee joint: a report about five cases. Knee Surg Sports Traumatol Arthrosc. 2005;13:598–602. 37. Phisitkul P, Wolf BR, Amendola A. Role of high tibial and distal femoral osteotomies in the treatment of lateral-posterolateral and medial instabilities of the knee. Sports Med Arthrosc. 2006;14:96–104. 38. James EW, Williams BT, LaPrade RF. Stress radiography for the diagnosis of knee ligament injuries: a systematic review. Clin Orthop Relat Res. 2014;472:2644–2657. 39. Laprade RF, Bernhardson AS, Griffith CJ, et al. Correlation of valgus stress radiographs with medial knee ligament injuries: an in vitro biomechanical study. Am J Sports Med. 2010;38: 330–338. 40. Sawant M, Narasimha Murty A, Ireland J. Valgus knee injuries: evaluation and documentation using a simple technique of stress radiography. Knee. 2004;11:25–28. 41. Khanna AJ, Cosgarea AJ, Mont MA, et al. Magnetic resonance imaging of the knee. Current techniques and spectrum of disease. J Bone Joint Surg Am. 2001;83-A(suppl 2 pt 2):128–141. 42. Schweitzer ME, Tran D, Deely DM, et al. Medial collateral ligament injuries: evaluation of multiple signs, prevalence and location of associated bone bruises, and assessment with MR imaging. Radiology. 1995;194:825–829. 43. Hayes CW, Brigido MK, Jamadar DA, et al. Mechanismbased pattern approach to classification of complex injuries of the knee depicted at MR imaging. Radiographics. 2000;20: S121–S134. 44. Nakamura N, Horibe S, Toritsuka Y, et al. Acute grade III medial collateral ligament injury of the knee associated with anterior cruciate ligament tear. The usefulness of magnetic resonance imaging in determining a treatment regimen. Am J Sports Med. 2003;31:261–267. 45. Lee JI, Song IS, Jung YB, et al. Medial collateral ligament injuries of the knee: ultrasonographic findings. J Ultrasound Med. 1996;15:621–625. 46. Gruber G, Martens D, Konermann W. Value of ultrasound examination in lesion of the medial collateral ligament of the knee joint. Z Orthop Ihre Grenzgeb. 1998;136:337–342. 47. De Maeseneer M, Vanderdood K, Marcelis S, et al. Sonography of the medial and lateral tendons and ligaments of the knee: the use of bony landmarks as an easy method for identification. AJR Am J Roentgenol. 2002;178:1437–1444. 48. De Maeseneer M. Medial and lateral capsular and supporting structures of the knee: MR imaging and sonography with anatomic correlation. JBR-BTR. 2001;84:171–172.
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