Version May 2024
INTRODUCTION — Injuries of the medial collateral ligament (MCL), also referred to as the tibial collateral ligament, occur frequently in athletes, particularly those involved in sports that require sudden changes in direction and speed, and in patients struck on the outside of the knee. Most heal well with conservative treatment, but some are associated with other significant injuries, and careful evaluation is needed.
The evaluation and management of MCL injuries are reviewed here. A general approach to the patient with knee pain and the management of other types of knee injuries are discussed separately:
●Knee pain in adults (see "Approach to the adult with unspecified knee pain" and "Approach to the adult with knee pain likely of musculoskeletal origin")
●Knee pain in children (see "Approach to acute knee pain and injury in children and skeletally immature adolescents" and "Approach to chronic knee pain or injury in children or skeletally immature adolescents")
●Ligament and meniscus knee injuries (see "Anterior cruciate ligament injury" and "Meniscal injury of the knee" and "Lateral collateral ligament injury and related posterolateral corner injuries of the knee" and "Posterior cruciate ligament injury")
EPIDEMIOLOGY
Incidence and risk factors — According to one systematic review, studies of the epidemiology of knee injuries are deeply flawed and should be interpreted cautiously [1]. Nevertheless, ligament injuries account for up to 40 percent of all knee injuries, and of these, medial collateral ligament (MCL) injuries appear to be the most common [2,3]. MCL tears accounted for 7.9 percent of all injuries in an observational study of 19,530 knee injuries in 17,397 athletes over a 10-year period [4]. The precise incidence of MCL injuries is unlikely ever to be known because many low-grade injuries go unreported. MCL injuries declined in number during the course of an 11-year study of injuries in the Union of European Football Associations (UEFA) [5].
The risk of MCL injury varies by sport. Association football (soccer) and basketball players appear to have a relatively high incidence, as do participants in contact sports such as wrestling, hockey, American football, and rugby [1,6]. MCL injuries are the most common knee injuries in American football at the high school, college, and professional levels [7]. The annual incidence among high school football players is 24.2/100,000 athletes [8]. MCL injuries are the most common traumatic knee injury resulting in time lost in professional soccer [9].
Whether the risk of MCL injury varies significantly by sex remains unclear, but some studies suggest that females are at higher risk [1,6]. A large survey study of United States high schools reported that females had a higher risk for knee injury than males playing the same sport [8]. Data from a prospective study of cadet athletes at the United States Military Academy suggest a significantly higher risk for isolated MCL injury among female intercollegiate athletes [6]. However, a four-year retrospective study using data from two large American injury registries reported a higher risk of MCL injuries among male collegiate athletes compared with their female counterparts, but a higher risk among female high school athletes compared with males [10].
Other potential risk factors of note include prior injury, higher level of play (eg, intercollegiate athletes in the United States are at higher risk than secondary school athletes), game participation (versus practice), and type of sport. Various other risk factors have been proposed, ranging from equipment (eg, ski bindings) to different shoe-surface interfaces, but no definitive data exist to confirm these claims. (See 'Mechanism of injury and healing' below.)
Association with other injuries — MCL injuries are often accompanied by damage to other structures, with higher-grade MCL injuries rarely occurring in isolation. Medial meniscal tears occur in up to 5 percent of MCL injuries, and trauma to other ligaments of the knee occurs in 20 to 78 percent of cases, depending upon the severity of injury [11]. Nearly 78 percent of Grade III MCL tears are associated with another significant injury to the knee, with the anterior cruciate ligament (ACL) involved in up to 95 percent of cases [12,13]. In addition, MCL injury appears to be associated with other injuries of the lower leg. In one case series of 303 patients treated surgically for pronation injuries of the ankle, the prevalence of MCL injury was nearly 4 percent (n = 12) [14].
High-energy trauma resulting in lower extremity fractures is associated with collateral ligament injury. In a large retrospective study of proximal tibia fractures (n = 32,441), 2.4 percent of patients sustained concomitant injuries to both the MCL and lateral collateral ligament (LCL), while 1.4 percent sustained isolated MCL injuries [15]. Risk factors associated with collateral ligament injuries included: obesity (odds ratio [OR] 1.6), young age (OR 1.9), distal femur fracture (OR 2.1), and higher-energy injuries.
Of note, among pediatric and adolescent patients, MCL injury can occur simultaneously with a patellar instability event (subluxation or dislocation). A single-center study reported that isolated MCL injuries were rare in youth overall, but up to 25 percent occurred in conjunction with a patellar instability event [16].
ANATOMY — Clinically important anatomy related to the medial collateral ligament (MCL, also referred to as the tibial collateral ligament) is described here. General anatomy of the knee is discussed separately. (See "Physical examination of the knee", section on 'Anatomy'.)
The MCL is part of the capsuloligamentous complex supporting the medial knee (picture 1 and figure 1). This complex contains static (eg, capsule, ligaments) and dynamic (eg, muscles) structures. The dynamic stabilizers include the vastus medialis, semimembranosus, gracilis, and sartorius muscles (figure 2 and figure 3).
The MCL is approximately 8 to 10 cm long and shaped like an hour-glass. It originates from the medial femoral condyle anterior to the adductor tubercle and inserts on the anterior medial tibia just distal to the pes anserine on the tibial metaphysis (figure 1 and picture 2). The MCL is well vascularized and innervated.
There are two accepted ways to describe the anatomy of the MCL and the medial knee. The classic description most referenced in the literature is based upon a series of 154 knee dissections [17]. This study describes three layers of anatomy: the first and most superficial is deep sartorial fascia, the second includes the superficial MCL and posterior medial complex ligaments (including the posterior oblique ligament), and the third includes the deep MCL and posterior medial capsule [17,18]. The deep MCL and posterior oblique ligaments have attachments to the medial meniscus. Therefore, the MCL and medial meniscus can be injured simultaneously. The superficial MCL has proximal and distal sections, and the instability pattern seen in injury can depend on the location of the injury. Other important medial structures include the medial patella-femoral ligament, adductor magnus tendon, medial gastrocnemius tendon, and medial hamstring tendon [19].
An alternative description divides the medial structures of the knee into anterior, middle, and posterior thirds. The anterior third includes the capsular ligaments and retinaculum, the middle third includes the superficial and deep MCL, and the posterior third includes the posterior medial complex (including the posterior oblique and popliteal ligaments) [20]. A bursa lies between the deep and superficial layers of the MCL (figure 4).
Overall, the MCL and related medial structures provide restraint against valgus stress and tibial rotation.
Researchers note that the MCL fibers provide relatively consistent isometric tension throughout knee flexion and extension, and this helps resist valgus stress to the knee. However, there is no universal agreement about the degree to which such resistance occurs in knee flexion versus extension, or about the relative contributions of the superficial and deep MCL fibers [19-22]. The posterior oblique ligament assists in resisting the stresses at the knee that occur with internal rotation and extension. The anterior cruciate ligament (ACL) (figure 2) provides a secondary restraint to valgus and rotational stress, particularly in full extension [20].
MECHANISM OF INJURY AND HEALING — The medial collateral ligament (MCL) is commonly injured (torn or sprained) in contact and collision sports, as well as sports that require significant twisting and torque of the lower extremity, such as football (soccer), basketball, tennis, American football, and skiing. The ligament may be injured via a direct valgus stress from a blow to the lateral aspect of the knee or via an indirect stress through abduction or rotation of the lower leg. Direct blows are more common and typically cause more severe injury [5,9,11]. Studies of MCL injuries sustained by elite football players in Union of European Football Associations (UEFA) report that three-quarters of MCL injuries occur from direct contact and are more commonly associated with foul play [5,9].
Injury through an indirect mechanism typically occurs when a shoe catches on a playing surface (eg, cleat catches on turf, sneaker adheres to a court surface) while the athlete is trying to change direction quickly. A similar force is generated when an athlete catches a tip or the inside edge of a ski or skate. This results in a valgus stress at the knee, often with external tibial rotation. The MCL may also be injured if the knee is forced into hyperextension. This can cause injury to multiple ligaments and, sometimes, the peroneal nerve [23].
MCL injuries heal in classic stages: hemorrhage, inflammation, repair, and remodeling. Scar tissue may form, with the amount of scarring depending upon both the degree and the location of the injury. In animal models, injury to the midsubstance of the MCL seems to demonstrate better healing than injury to the proximal or distal ligament [24].
PHYSICAL EXAMINATION
Overall approach — The general knee examination is discussed in detail separately. Aspects of the examination of particular importance for assessment of the medial collateral ligament (MCL) are described below. (See "Physical examination of the knee".)
Examination of an injured knee is best accomplished within 20 or 30 minutes of the injury before pain, swelling, and muscle spasm make assessment difficult. Often, the examination cannot be performed in this timeframe. In some cases, it is best to provide symptomatic treatment and have the patient return for reevaluation once symptoms have subsided.
The patient must be relaxed for the knee to be examined properly. This can be accomplished by having the patient concentrate on relaxing their hip muscles, providing adequate support for the injured limb throughout the examination, monitoring tension in the hamstrings, and performing examination maneuvers gently.
Examine the knee systematically. Begin with the uninjured knee and compare findings in the uninjured and injured joints.
Look closely for other injuries that may occur in association with an MCL sprain, particularly those of greater severity. These include injuries to the meniscus, distal femur or proximal tibia, anterior cruciate ligament (ACL), posterior oblique ligament, and adjacent muscles [23,25]. A neurovascular examination of the distal leg is necessary in the setting of a traumatic knee injury to ensure the peroneal nerve (figure 5) and popliteal artery have not been damaged and there are no signs of a developing acute compartment syndrome. (See 'Differential diagnosis' below.)
Inspection — Observe the patient's stance and gait. Inability to bear weight suggests the presence of a significant injury necessitating imaging. Clinical guidelines that help to determine when such imaging is necessary are reviewed separately. (See "Approach to the adult with knee pain likely of musculoskeletal origin", section on 'Imaging in the evaluation of acute knee pain'.)
The knee should be inspected carefully for swelling, ecchymosis, and deformity. While localized swelling can develop, joint effusions are not common in isolated MCL sprains, particularly with lower-grade injuries. However, severe MCL sprains often involve concomitant injuries, such as meniscal and ACL tears, which can cause a joint effusion. (See "Meniscal injury of the knee" and "Anterior cruciate ligament injury".)
Palpation — Palpation is important for diagnosing MCL sprain and ruling out associated injuries (eg, avulsion fracture, tibial plateau fracture, and muscle, tendon, or ligament damage). Palpate bony and soft tissues, noting areas of tenderness, warmth, and crepitus.
Bony landmarks to palpate include the joint lines (medial (picture 1), posterior medial corner, posterior, and lateral (picture 3)), femoral condyles, tibial plateau, patella and patellar facets, tibial tubercle, tibial metaphysis, and the pes anserine area.
Soft tissues to palpate include the entire length of the MCL, which originates at the medial femoral condyle and insertions along a relatively lengthy footprint on the medial tibia. The clinician should also palpate the patellar retinaculum, patellar and quadriceps tendons, extensor mechanism, and adjacent muscles, including the gracilis, sartorius, semimembranosus, semitendinosus, medial gastrocnemius, and quadriceps, as tenderness in these structures can indicate concomitant injury.
Although rigorous studies are lacking, focal tenderness over a segment of the MCL is reported to be up to 78 percent accurate in diagnosing the location of an MCL tear [11]. However, it is often difficult to distinguish a midsubstance MCL tear from an injury to the medial meniscus.
Range of motion and strength testing — Perform range of motion testing using the following sequence: active, passive, and then resisted. The cardinal motions of the knee are flexion and extension. Typical range of motion for the knee ranges from several degrees of recurvatum (ie, past full extension) to 140 degrees of flexion, but actual ranges vary widely among patients. Therefore, it is important to compare the injured and uninjured knees.
Assess the knee for its full range of motion, noting the ease with which it moves and any limits to mobility. Also note any pain and where in the arc of knee movement pain occurs.
Passive range of motion need not be assessed if active range of motion is full and unrestricted. If active motion is limited, assess passive mobility. While doing so, apply gentle pressure, thereby compressing the knee joint, to determine if a true block to motion exists. A true block suggests the presence of an intraarticular derangement, such as an intraarticular loose body or a torn and displaced meniscus. Pain from an isolated MCL injury can limit active motion, particularly terminal knee extension and flexion beyond 100 degrees, but generally does not constrain passive motion. Of course, pain may limit how much passive motion the patient permits.
Resisted motion is performed last with the patient seated and the knee in neutral position (90 degrees of flexion). Note the level of strength and any pain with isometric contraction. Inability to perform a straight leg raise (hip flexion against gravity with knee in full extension) is a concerning finding and should be investigated with suitable imaging. Such inability may be secondary to a large knee effusion causing quadriceps inhibition or disruption of the extensor mechanism.
Special tests and grade of injury — Perform a valgus (or abduction) stress test with the knee in both 30 degrees and 0 degrees of flexion looking for joint laxity. Baseline joint laxity varies widely so it is important to compare the injured and uninjured knees.
A valgus stress test is performed with the patient supine, the hip in slight flexion and abduction, and the knee slightly flexed (picture 4 and movie 1). The test can be performed in the following manner: secure the leg by pinning the patient's ankle or foot between your elbow and the side of your body. Next, place both hands on the patient's proximal lower leg with your fingers over the medial and lateral joint lines. Exert a gentle valgus stress across the knee joint by pushing on the ankle or foot with your elbow, while holding the proximal leg in place with your hands. As you exert this gentle valgus stress, feel how much the medial joint line widens.
If the valgus stress test reveals laxity at approximately 30 degrees of flexion, the superficial portion of the MCL may be injured. Laxity at 0 degrees of flexion suggests injury to the deeper structures of the MCL and possible disruption of a cruciate ligament (the anterior cruciate ligament [ACL] and posterior cruciate ligament [PCL] act as secondary restraints to valgus stress). Both the posterior medial corner and posterior oblique ligament may be damaged when MCL and ACL injuries coexist. (See 'Anatomy' above and "Physical examination of the knee", section on 'Assessing joint stability' and "Anterior cruciate ligament injury" and "Posterior cruciate ligament injury".)
The Lachman test (picture 5) is the most reliable examination maneuver for assessing the integrity of the ACL in this setting. A pivot shift test (figure 6) may be inaccurate if a complete tear of the MCL exists. These tests are discussed separately. (See "Anterior cruciate ligament injury", section on 'Physical examination'.)
The degree of joint opening and the presence or absence of a distinct endpoint when performing a valgus stress examination determines the grade of MCL injury:
●Grade I – Less than 5 mm of joint opening accompanied by a solid endpoint represents a Grade I (or mild) injury. In such cases, a few fibers are torn, but the MCL is structurally intact.
●Grade II – Anywhere from 5 to 9 mm of joint opening represents a Grade II (or moderate) injury. Usually a firm or perceptible endpoint is present. This suggests an incomplete MCL tear with some remaining ligamentous integrity.
●Grade III – 10 mm or more of joint opening with no perceptible endpoint indicates a Grade III (or significant) injury. This is a complete tear. In addition, this degree of laxity suggests that other knee ligaments may be injured.
Rotational instability of the tibia can be assessed by externally rotating the foot with one hand while palpating the joint line with the other [26]. If increased rotation compared with the uninjured knee is noted, this suggests anteromedial instability due to an injury of the deep MCL and possible injury to the posteromedial corner [22]. In larger patients, rotational stability can be assessed by keeping the patient's thighs on the table and allowing the knee and foot to drop over the edge. The examiner then compares the degree of joint opening while applying a rotational stress to the injured and uninjured knees.
IMAGING
Radiographs — Plain radiographs are generally not necessary in the evaluation of an isolated medial collateral ligament (MCL) injury. However, they can be helpful in certain situations and are indicated in the setting of major trauma. In the skeletally immature patient, plain radiographs enable assessment of the physis.
Radiographs should be obtained if the patient is unable to bear weight or if focal bony tenderness, gross deformity, or an effusion is present. The Ottawa knee rules provide guidance for determining when imaging is necessary in the setting of knee trauma. Clinical guidelines that help to determine when such imaging is necessary are reviewed separately. (See "Approach to the adult with knee pain likely of musculoskeletal origin", section on 'Imaging in the evaluation of acute knee pain' and "Radiologic evaluation of the acutely painful knee in adults".)
When radiographs are deemed necessary, the following views should be obtained (image 1):
●Anterior-posterior (AP)
●Lateral
●Patellar (45-degree flexion)
In some cases, a tunnel view may be helpful. Although rarely obtained, stress views may help to identify joint opening, particularly in patients with a Grade III MCL tear or injuries to multiple knee ligaments (image 2) [26,27].
The Pellegrini-Stieda sign is a calcification (usually crescent-shaped) of the MCL at the medial femoral condyle (image 3) and is associated with chronic injury or insufficiency of the MCL [28]. The calcification may cause focal pain but is not associated with specific clinical findings.
Magnetic resonance imaging — Magnetic resonance imaging (MRI) is seldom necessary to assess minor (ie, isolated, low grade) MCL injuries. MRI can be used to define the extent of a severe MCL injury and to look for associated injuries (eg, anterior cruciate ligament [ACL] tear) if the physical examination is limited or major knee trauma is suspected [29]. Although injury severity can be categorized into three grades based on MRI findings, such grading does not correlate consistently with clinical severity [29,30]. MRI is perhaps most useful for assessing a clinical Grade III injury, as it can sometimes distinguish the superficial and deep layers of the MCL, as well as determining the location of the tear (midsubstance versus femoral or tibial insertion) [31]. These distinctions may determine the need for surgery, particularly if there is entrapment of the deep MCL or the location of the tear is at its tibial insertion, where a higher grade tear is more likely to require surgery [22,32].
MRI findings typically include bursal swelling between the deep and superficial layers, subcutaneous soft tissue swelling, and hemorrhage and tearing of MCL fibers. Fiber damage ranges from internal derangement to complete disruption (image 4 and image 5 and image 6 and image 7). Other MRI findings may include hemarthrosis, contusion of the lateral femoral condyles or the tibial plateau, meniscal injury, damage to other ligaments, and (rarely) partial avulsion of the medial femoral condyle. Typically, coronal sequences provide the best visualization of the MCL and posterior medial corner [11].
Of note are skeletally immature children, who are at risk of an avulsion fracture as well as a true intrasubstance tear. Avulsion fractures of the MCL attachment at the medial femoral condyle or tibia may be occult (unseen on plain radiographs), particularly if the avulsion is non-osseous. Such injuries may delay recovery or warrant lengthier treatment in a hinged knee brace, or even surgery. The clinician should have a lower threshold for obtaining an MRI in a skeletally immature child, especially if significant instability is present on examination or recovery is delayed [33].
Various clinical entities that may masquerade as an MCL injury on MRI include bursitis, osteoarthritis, retinaculum injury, and medial meniscus cyst [34]. While MRI remains the gold standard for imaging the MCL, there are cases of acute injury not identified by MRI [35]. Thus, clinical examination remains a cornerstone of diagnosis. (See 'Differential diagnosis' below and 'Physical examination' above.)
Ultrasound — Use of point-of-care ultrasound (US) in the evaluation of knee injuries, including isolated injuries of the MCL, is growing. US identifies MCL lesions on the basis of abnormal sonographic appearance and quantitative assessment of joint opening (image 8 and movie 2). (See "Musculoskeletal ultrasound of the knee".)
In the hands of experienced sonographers, US is an accurate tool and the preferred imaging study when an isolated MCL injury is strongly suspected. US is less useful for visualizing the ACL and should not be considered definitive imaging if there is concern for multiligamentous knee injury.
Multiple studies have investigated US as a low-cost, rapid, and accurate tool for assessing MCL tears [22,36-40]. In a study of 255 patients presenting to the emergency department with possible MCL tear, US demonstrated a sensitivity, specificity, positive and negative predictive values of 84, 94, 81, and 95 percent, respectively [39]. Using MRI as the gold standard, 55 patients were diagnosed with an MCL tear.
DIAGNOSIS — The diagnosis of a medial collateral ligament (MCL) injury is made clinically based upon the history, clinical presentation, and examination findings, and is generally straightforward. The mechanism typically involves a direct blow to the knee (usually the lateral knee) or a shoe catching while the athlete is attempting to change direction rapidly; common examination findings include focal tenderness over the MCL and a positive valgus stress test. Knowledgeable clinicians can use point-of-care ultrasound (US) to confirm the diagnosis. MRI may be used to make a definitive diagnosis and reveal the extent of injury, including to other structures, but is rarely necessary except in cases of severe trauma or when a major concomitant injury is suspected.
DIFFERENTIAL DIAGNOSIS — The diagnosis of a medial collateral ligament (MCL) sprain is made clinically and is generally straightforward. However, the examiner should be alert to other potential injuries, particularly to the anterior cruciate ligament (ACL), trauma to which frequently accompanies higher-grade MCL tears. Typically, knee injuries involving multiple ligaments present with significant joint effusion and instability in the sagittal plane that are not present with an isolated MCL injury. The diagnosis may be missed if the patient presents several days or weeks after the inciting event. (See "Anterior cruciate ligament injury".)
The mechanism responsible for MCL sprains can cause injury to static structures in the posterior medial corner of the knee, the medial meniscus, and medial-side muscles and their insertions, such as the vastus medialis, pes anserine, and semitendinosus [41]. With an isolated MCL injury, focal tenderness and swelling are typically limited to the course of the MCL itself. Correlation of clinical anatomy with examination findings is important as, for instance, a true joint effusion and joint line tenderness increase the likelihood of an associated meniscal tear, prompting the clinician to seek further imaging (eg, MRI). (See "Meniscal injury of the knee".)
A knee (ie, tibiofemoral) dislocation causes multiple severe ligament injuries, including MCL sprain or tear, and can pose a threat to the limb through arterial disruption. The mechanism usually involves major trauma (eg, motor vehicle collision or high-speed sports) and results in a large hemarthrosis and abnormal knee alignment. Of note, knee dislocations can spontaneously reduce prior to medical evaluation, making diagnosis difficult. (See "Knee (tibiofemoral) dislocation and reduction".)
Other entities to be considered in the differential diagnosis of an MCL sprain include osteoarthritis or rheumatoid arthritis, medial joint compartment arthrosis (which may present with an examination finding of "pseudo laxity"), patellar subluxation or dislocation, bony injury to the medial femoral condyle or medial proximal tibia, osteochondritis dissecans, extensor mechanism injury, proximal medial gastrocnemius strain, and distal medial hamstring strain. The approach to the patient with undifferentiated knee pain is discussed separately. (See "Approach to the adult with unspecified knee pain" and "Approach to the adult with knee pain likely of musculoskeletal origin" and "Clinical manifestations and diagnosis of osteoarthritis", section on 'Knee'.)
In children, ligaments exhibit greater relative tensile strength, and physeal injuries should be included in the differential diagnosis. In skeletally immature athletes with medial knee trauma, physeal injuries should be ruled out before considering the diagnosis of MCL injury. Typically, this can be accomplished with plain radiographs but may require advanced imaging. (See "Approach to acute knee pain and injury in children and skeletally immature adolescents", section on 'Anatomic considerations' and "Approach to acute knee pain and injury in children and skeletally immature adolescents", section on 'Specific conditions'.)
INDICATIONS FOR CONSULTATION OR REFERRAL — Surgical treatment for an isolated medial collateral ligament (MCL) injury is rarely necessary. Patients with an isolated MCL injury associated with significant knee instability that persists despite proper conservative treatment should be referred to an orthopedic surgeon. Consultation is advised if a posteromedial corner injury is suspected, as these injuries may have a better outcome with surgical treatment [42]. Otherwise, most experts agree that surgery for MCL repair is indicated only for patients with major concomitant injuries.
Immediate referral to a surgeon is required for any open fracture, neurovascular deficit, or suspected tibiofemoral dislocation. Keep in mind that tibiofemoral dislocations can reduce spontaneously prior to evaluation; suspect the injury in any patient with a highly unstable knee following significant trauma. Patients who have sustained high velocity trauma (eg, automobile accident, downhill skiing at high speed) are best evaluated in the emergency department. (See "Knee (tibiofemoral) dislocation and reduction".)
Referral to an orthopedic surgeon is necessary for the following:
●Knee injury involving multiple ligaments (unstable knee).
●Angulated or displaced fractures.
●Suspected injury of the posterior medial corner of the knee. These often involve the posterior oblique ligament and possibly other structures (eg, meniscus), and demonstrate anteromedial rotatory instability [41,42].
●Persistent pain (typically six weeks or longer, in the authors' experience) and tenderness along the proximal MCL, which may indicate injury to the ligament's deep fibers [43].
Such injuries may only be diagnosed with MRI. A clinical sign consistent with this injury is pain or instability (subluxation of the tibia) elicited by pushing the tibial plateau into the distal femur (axial load) while internally rotating the tibia. This maneuver is performed with the patient supine and the hip slightly flexed.
●Distal MCL injuries.
Tears of the ligament's tibial insertion do not heal as readily as proximal or midsubstance injuries and may result in a "Stener-type" lesion, in which one flap of the torn ligament becomes caught within the tibiofemoral joint [44,45].
●Injuries involving the physis.
Multiple studies have demonstrated the success of nonoperative treatment of MCL tears, including complete tears (ie, Grade III injury), even in the face of concomitant anterior cruciate ligament (ACL) rupture [18,46-49]:
●A randomized controlled trial of 47 patients with combined Grade III MCL tears and ACL rupture found that operative repair of the MCL provided no benefit over nonoperative treatment [50,51]. Using quantitative instruments (eg, KT-1000 arthrometer) and validated assessment tools, the researchers were unable to identify any significant differences in stability, motion, strength, or return to activities between the two groups.
●Another randomized trial involving 200 patients reported no difference in outcome among patients with MCL injuries treated operatively or nonoperatively [52].
However, there is always a risk of residual laxity following MCL injury, particularly Grade II or Grade III tears. One prospective observational study found greater anteroposterior and valgus-varus laxity following surgical repair of the ACL in patients with combined ACL and MCL injuries compared with patients with isolated ACL rupture [53]. However, this increased laxity had no clinical significance.
Many experts delay repair of a ruptured ACL until adequate healing of the MCL has been achieved and knee motion is near normal, but controversy persists about the best approach for these patients [54-56]. (See "Anterior cruciate ligament injury".)
INITIAL TREATMENT
Basic care — The initial treatment of a medial collateral ligament (MCL) injury consists of the following measures:
●Control pain with rest, ice, compression, elevation (knee above heart level), and analgesics as needed.
●Protect the joint from further injury.
●Obtain appropriate consultation or transfer to the emergency department for knee injuries involving multiple ligaments or major trauma. (See 'Indications for consultation or referral' above.)
Ice can be applied for approximately 20 minutes every two to three hours for two or three days following the injury. Gentle compression with an elastic bandage and protected motion using a brace and crutches are often helpful. Weight bearing is as tolerated. A brief period in a functional or hinged brace is preferable to a straight-leg knee immobilizer because the latter can result in joint stiffness. Bracing helps protect the torn MCL from valgus stresses that may exacerbate injury and delay healing. (See 'Follow-up and rehabilitation' below.)
Acetaminophen is commonly used for acute pain control and appears to have no adverse effect upon healing [57]. Nonsteroidal antiinflammatory drugs (NSAIDs) are frequently used for analgesia following an acute MCL injury. While NSAIDs provide effective short-term pain relief, their effect on ligament and bone healing remains unclear. This issue is discussed separately. (See "Nonselective NSAIDs: Overview of adverse effects", section on 'Possible effect on tendon injury'.)
The goals of early treatment of any ligament injury are to regain mobility and function while protecting the injured joint. This enables the patient to return to activity as rapidly and as safely as possible.
Animal models have demonstrated weaker ligament healing and poorer outcomes in immobilized joints, and clinical trials support this finding [24]. Casting and surgery, once the standard approach to MCL treatment, provide no benefit. Observational data and clinical studies of rehabilitation of ligamentous injuries of the ankle demonstrate that early motion improves ligament healing and strength. Thus, early mobilization has become a fundamental principle of care [3]. Temporary bracing may be needed to support unstable joints during ambulation, but prolonged immobilization of any type is to be avoided in MCL injuries of all grades.
PRP and other injection therapies — A number of injectable therapies, including platelet-rich plasma (PRP), have been used or proposed for the treatment of acute soft tissue injury, including ligament tears, but evidence supporting their use in humans is limited and conflicting. Studies of these interventions in the setting of acute MCL injury are limited to case reports [58-60]. The evidence and appropriate role of these therapies for soft tissue injury are discussed separately [59,60]. (See "Overview of the management of overuse (persistent) tendinopathy", section on 'Adjunct and investigational treatments' and "Biologic therapies for tendon and muscle injury", section on 'Studies of PRP and ABI for tendon injury'.)
FOLLOW-UP AND REHABILITATION — The initial examination of the medial collateral ligament (MCL), particularly if the patient presents several days after the injury, may be limited by swelling and pain. In such cases, we generally reexamine the patient within one week to determine the presence of associated injuries and the need for further imaging, referral, or bracing, and to begin the rehabilitation process.
It may be best to have the patient evaluated in the emergency department if the injury involved a high velocity mechanism (eg, automobile accident, downhill skiing at high speed) or tibiofemoral dislocation may have occurred. The timing of subsequent follow-up appointments is dictated by the severity of the injury, use of bracing, and the patient's recovery. (See 'Indications for consultation or referral' above.)
In general, early joint motion is a central concept of rehabilitation and is encouraged in patients with an MCL injury. Weight bearing and activity are advanced as tolerated by the patient.
Bracing, while commonly recommended, is controversial. If bracing is deemed necessary, usually for pain relief, a hinged knee brace is best. Brace settings should allow for as much flexion as the patient can tolerate but should prevent full extension. Typically, the extension stop is set at 10 to 20 degrees of flexion. For more severe MCL injuries or if the knee has a valgus deformity, more extensive bracing may be needed to mitigate valgus forces across the injured ligament. More extensive bracing entails using a brace that extends further (both proximally on the thigh and distally on the leg) and wearing it more often.
Rehabilitation of an MCL injury is similar to other musculoskeletal injuries. The first goal is to restore active range of motion. Next, a gradual progression of exercises is used to improve strength, proprioception, agility, and general fitness. Finally, athletes perform sports-specific activities and return to play. This approach is sometimes referred to as functional rehabilitation. A program for uncomplicated Grade I and Grade II injuries is provided separately. (See "Rehabilitation of common knee injuries and conditions", section on 'Medial collateral ligament of the knee'.)
●A typical progression of strengthening exercises for the MCL-injured knee begins with isometric quadriceps contractions and progresses to isotonic exercises through a short arc (eg, quarter squat). Gradually, the range of motion and resistance for these exercises is increased.
●The progression of general activity begins with walking, moves to jogging as tolerated, then progresses to three-quarters speed, then straight ahead sprinting, then to movement in multiple directions (sprinting with curves to figure 8 running to side-to-side bounding), and finally to sports-specific drills and return to competition.
While these general principles can easily be taught in the office, the guidance of a physical therapist, athletic trainer, or other knowledgeable professional is often useful.
Multiple prospective observational studies attest to the effectiveness and decreased morbidity (primarily decreased range of motion) of this approach to rehabilitation for isolated MCL injuries when compared with surgical repair or immobilization [61-63]:
●Lateral hinged braces and functional rehabilitation were used as part of the treatment protocol for American football players with severe (Grade III) MCL injuries [61]. Follow-up over several years showed results comparable with those achieved with surgery or immobilization, but with less morbidity and faster return to sports.
●In another study, 38 individuals with isolated, partial MCL injuries treated nonoperatively were followed for 10 years and had good functional outcomes using a validated assessment tool (Lysholm scale) [62].
●In a study of 40 matched patients, those with isolated MCL injuries treated nonoperatively achieved high functional scores at 10 year follow-up [63].
The evidence for adjunct treatment modalities such as therapeutic ultrasound (US), laser, electrical stimulation, and glucocorticoid injection is limited and based primarily upon animal models [24,64-67]. Given the success of functional rehabilitation, adjunct treatments are seldom needed.
COMPLICATIONS — Complications of minor (Grade I) medial collateral ligament (MCL) injuries rarely occur. In more severe injuries (Grade II or III), instability can persist and may limit knee function and sports participation [31].
As with any ligamentous injury, MCL tears of any grade may cause some residual pain. In rare instances, this may lead to a complex regional pain syndrome. (See "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis" and "Complex regional pain syndrome in adults: Treatment, prognosis, and prevention".)
Recurrence of injury is probably the most significant complication of an MCL tear. While the incidence of recurrence is unknown, the risk is greater for higher-grade injuries. In a small series of patients with isolated Grade III MCL injuries, the incidence was reported to be 23 percent [61].
Scarring and adhesions within the joint (ie, arthrofibrosis) most likely occur from excessive joint immobilization [68].
RETURN TO SPORT
Timing — Return to sports or heavy activity following an isolated medial collateral ligament (MCL) injury is generally accomplished quickly and safely, although there is no high-quality evidence to determine the optimal recovery period. The appropriate time to resume activity varies and is dictated by when the patient regains full motion, strength, and the ability to perform necessary sports or work-specific tasks. This, in turn, depends upon the patient's preinjury level of function and the severity of the injury. Typically, return to full activity can be achieved within three to six weeks.
Prophylactic bracing — The use of a prophylactic knee brace to prevent injury or reinjury to the MCL is controversial, and there is little high-quality evidence to guide decision-making [69]. Although functional knee bracing is used with some frequency in certain sports and certain positions (eg, linemen in American football), there is no clear evidence that such use decreases the incidence of knee injuries, specifically ligamentous injuries such as MCL tears [69-71].
An early review of studies on bracing found mixed results [3]. The authors commented that braces may create a mechanical disadvantage in some instances. A prospective observational study of 987 college American football players with a total of 155,772 exposures reported a nonsignificant trend toward MCL injury prevention overall in those using a brace [72,73]. However, the risk was increased among backfield players using braces. Subsequent studies have found no clear benefit [9].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Knee pain" and "Society guideline links: Meniscal injury" and "Society guideline links: Anterior cruciate ligament injury" and "Society guideline links: Patellofemoral pain".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Knee pain (The Basics)")
●Beyond the Basics topic (see "Patient education: Knee pain (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Epidemiology – Medial (or tibial) collateral ligament (MCL) injury is among the most common athletic knee injuries. (See 'Epidemiology' above.)
●Mechanism of injury – The MCL provides the primary restraint to valgus motion and external tibial rotation of the knee. The MCL is injured most often through a valgus stress from a direct blow to the lateral aspect of the knee or through an indirect stress from abduction or rotation of the lower leg while the foot is planted. Direct blows typically cause more severe injury. (See 'Anatomy' above and 'Mechanism of injury and healing' above.)
●Grade of injury – MCL injuries are categorized by grade: a Grade I injury is minor and stable; a Grade II injury is a partial tear and demonstrates some instability; a Grade III injury is a complete tear and creates gross instability. (See 'Special tests and grade of injury' above.)
●Concomitant injury and differential diagnosis – While the MCL is often injured in isolation, concomitant injury to the anterior cruciate ligament (ACL), medial meniscus, and posterior medial corner must be excluded. (See 'Differential diagnosis' above.)
●Physical examination and diagnostic imaging – MCL injury can be diagnosed by a careful history and physical examination alone in most cases. Bedside ultrasound (US) can assist with diagnosis. Other imaging, including plain radiographs, stress radiographs, and possibly magnetic resonance imaging (MRI), is used most often to exclude concomitant injury. (See 'Physical examination' above and 'Diagnosis' above.)
●Treatment and indications for orthopedic referral – We suggest that isolated MCL injuries be treated nonoperatively with functional rehabilitation (Grade 2B). Surgery is indicated only for injuries refractory to rigorous conservative treatment and those with gross knee instability, associated intra-articular injury, or multiple ligamentous injuries. (See 'Indications for consultation or referral' above.)
●Bracing – Functional or hinged bracing may be helpful early during rehabilitation, particularly for unstable injuries. However, the knee should not be fully immobilized at any time. Benefit from prophylactic bracing remains unproven. (See 'Follow-up and rehabilitation' above and 'Prophylactic bracing' above.)
●Physical therapy and return to play – Functional rehabilitation involves a gradual progression of exercises to improve range of motion and strength. Rehabilitation of mild MCL injuries can often be completed quickly, with athletes returning to play within a few weeks. The long-term prognosis for all grades of MCL injury is excellent. (See 'Follow-up and rehabilitation' above and 'Return to sport' above.)
ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges William W Dexter, MD, who contributed to earlier versions of this topic review.
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