LCL Reconstruction

Lateral Collateral Ligament – Encyclokneedia

Introduction:

Lateral Collateral Ligament (LCL) injuries are commonly a result of extensional, rotational, translational, and varus forces applied through the knee, and may occur in contact or non-contact activities [10]. Patients often complain of lateral or posterolateral pain of the knee and may exhibit knee swelling, locking, and instability with cutting or pivoting movements [2].

LCL injuries are estimated to account for 8% of all knee injuries, with only posterior cruciate ligament (PCL) injuries being less common [3]. Isolated LCL injuries are relatively uncommon due to the complex anatomy of the knee joint along with the proximity of the LCL to other structures in the posterolateral corner (PLC). Often, the forces necessary for injury also cause damage to other components of the PLC, PCL, anterior cruciate ligament (ACL), and the lateral meniscus [9]. One unique way that isolated LCL injuries can occur is when a force is placed across the knee that is flexed and loaded from the outside of the foot as can occur in rock climbing or the yoga position of pigeon pose. More commonly the LCL is disrupted in conjunction with other knee ligaments especially other components of the PLC, or posterolateral corner.

In a study performed by Majewski et al. in 2006, it was found that approximately 25% of LCL injuries involved at least one other concurrent injury of the knee, and a study by Kramer et al. in 2017 found that 25% of LCL injuries in children and adolescents involved a concurrent PLC injury.

Anatomy:

The knee joint is composed of the distal femur and proximal tibia and fibula, connected by a capsule, with numerous soft tissue structures overlying and surrounding the joint, providing support and stability. These soft tissue structures are found close together and may at times be indistinguishable from one another. Given this challenge, these structures are often grouped together and referred to as the “lateral complex” of the knee, which is further broken down into layers. The layers, from superficial to deep are as follows:

1. Iliotibial band, biceps femoris (short head and long head)
2. Lateral Collateral Ligament
3. Arcuate ligament, Popliteal tendon, Popliteofibular tendon, Joint capsule

The LCL has the appearance of a cord-like structure on imaging, and most commonly originates at the lateral epicondyle, which is a bumpy outcropping on the outside of the knee [1]. The insertion is at the anterior point of the fibular head, as a component of the conjoined tendon which includes the biceps femoris tendon [6]. The LCL can be palpated on yourself by crossing one leg over the other which stretches the ligament, then finding the joint line and palpating a small rope like structure that feels like a tight shoe lace running from the fibula (the most prominent bone on the outside of the knee) up the femur. IF the knee if flexed to 90 degrees the LCL will run in line with the shaft of the tibia or leg bone.

Perfusion of the LCL is accomplished via the network of arteries that arise from the popliteal artery, with the superior and inferior lateral genicular arteries serving the primary role. Innervation is supplied by both the common fibular nerve and tibial nerve [8].

Although it is highly debated and probably occurs in some fashion in all people an estimated 9% of people have an distinct and identifiable accessory ligament called the anterolateral ligament (ALL) that provides support to the LCL and is more involved in rotational control of the knee. The ALL originates at the lateral femoral epicondyle, and has two segments, one which inserts at the fibular head and the other which inserts at the posterior aspect of Gerdy’s tubercle. The primary role of this ligament is to prevent excess internal tibial rotation [7]. It is very important to distinguish between injury to the ALL and LCL as the effects of these injuries require different treatment strategies and they can be very hard to elucidate since they are very near one another. We have written about the ALL elsewhere in the EncycloKNEEdia.

Variations of the LCL are somewhat uncommon but have been documented to show changes in origin and shape. The most common variations to the origin are at the [5]:

1. Apex of the lateral epicondyle
2. Fovea posterior to the lateral epicondyle
3. Posterior and proximal to the lateral epicondyle, posterior to the origin of the popliteal tendon.

Variations of shape and pattern along with their estimated incidences are [7]:

1. Cord type (70%)
2. Band type (26%)
3. Mixed band and cord (2%)
4. Y Shaped (2%)

History:

LCL injuries are categorized into grades 1-3 with respect to their severity. Diagnosis and grade determination are made through use of MRI.

• - Grade 1: Sprain of ligament, imaging demonstrates fluid surrounding the midsubstance or insertion points. Results in tenderness and swelling.
• - Grade 2: Partial tear of the LCL at either insertion or midsubstance. Results in tenderness, swelling, and mild to moderate laxity of the knee (5-10 mm).
• - Grade 3: Complete tear of the LCL. Results in varying levels of pain, swelling, laxity greater than 10 mm which may not have a clearly defined endpoint.

Most commonly, these injuries result from a strong varus force in the context of a hyperextended knee, leading to a PCL injury which typically includes the LCL. Isolated LCL injuries are more often the result of a lower grade varus force with some degree of rotational force applied to the tibia [9]. Given the uncommon nature of isolated LCL injuries, it can be challenging to determine specific risk factors, however researchers have compiled a list of factors that likely lead to an increased risk of LCL injury specifically [3]:

1. Female gender
2. Sports competition (Not observed in practice, likely secondary to increased risk taking due to higher stakes than when in practice)
3. Sports with high rates of physical contact
4. Activities which require pivoting or cutting movements, jumping or landing.

Sports known to pose such risks include American football, soccer, skiing, tennis, and gymnastics. In epidemiological studies, tennis and gymnastics were found to have the greatest number of LCL injuries [4].

In the case of isolated injuries these patients will complain of what felt like a relatively mild pop followed by mild to moderate pain that typically does not involve swelling of the joint itself. This is followed by a sense that ‘something is not right’ or instability that prevents continued activity. It will often be possible to continue weight bearing but with pain and a sense of instability. Patients will often prefer to use a brace.

Combined injuries are usually described as excessive lateral pain relative to the remainder of the knee and are often associated with substantial swelling due to the related intraarticular (inside the joint) injury. It will often not be possible to bear weight due to the pain, swelling, and instability.

Physical Exam:

On physical examination, the most common finding is tenderness along the lateral knee, often with localized swelling. The LCL can palpated when the patient is in the supine position and has their knee flexed 90 degrees and is even more prominent when the patient externally rotates their hip to place ankle on contralateral lower leg (known as a ‘figure four’ position.) The LCL may be difficult to identify depending on the patient, and thus the examiner should start palpation at the origin and follow the LCL as it moves distally and crosses the joint line towards the fibular head. Gait abnormalities are also common exam findings, specifically a varus thrust gait which is seen when a gap develops on the lateral side of the knee and the patient adjusts their weight to return their knee to its normal alignment. Patients may also compensate when trying to ambulate by maintaining a flexed knee to prevent it from fully extending. This is done to reduce feelings of instability as the tibia may experience excessive internal rotation without normal support of the LCL.

The LCL almost exclusively tears a few mm above the attachment on the fibula and a patient will often have point tenderness in this location.

Certain physical exam maneuvers may be helpful when assessing patients with suspected knee injuries and positive exam findings may also help reveal associated injuries to other structures in the knee. The four most common exam maneuvers to help further assess a knee injury are:

1. External rotation recurvatum test – Assess for (concurrent) ACL injury
2. Posterolateral drawer test – Assess for PLC injury, primarily popliteal or popliteofibular ligament
3. Reverse shift test – Assess for PLC injury – primarily in the Iliotibial tract
4. Dial test (30 and 90 degrees) – Help assess for for PLC injury

Many times, simply placing the knee in the figure – 4 position and palpating the torn ligament is adequate for diagnosis (or to arouse suspicion) in lower energy or isolated cases.

It is important to remember that LCL injuries rarely occur in isolation and often include injury to another structure such as the PLC or ACL, and therefore while positive findings on these exam maneuvers may support the diagnosis of an LCL injury, further evaluation of other structures of the knee is warranted [11].

Imaging:

Because the LCL is superficial, ultrasound may be a non invasive option to determine the severity of injury. Grade 1 and 2 injuries appear thickened and hypoechoic. Grade 3 injuries appear as hypoechoic thickening of the LCL with lack of fiber continuity and dynamic laxity of the lateral joint line. Associated hemorrhage and edema may also be present [14. Unfortunately, because isolated injuries are rare MRI is typically required to assess for related pathology or injuries and this limits the practical utility of ultrasound. In clinical practice, it is therefore more common to obtain an MRI if there is suspicion of LCL injury.

MRI is the gold standard of imaging for soft tissue evaluation, with sensitivity and specificity reported to be extremely high [13] and thus all patients with significant knee injuries undergo MRI when available. Additionally, radiographs are obtained in these patients to look for structural abnormalities such as the presence of an Arcuate sign (avulsion fracture of the styloid of the proximal fibula) or a Segond fracture (avulsion fracture of the lateral tibial plateau), both of which are pathognomonic (pathognomonic is fancy doctor talk for “it is definitely this”) for PLC injury or ACL injury respectively [12].

In my practice, these injuries are very easy to miss and MRI alone is not always adequate. When there is doubt or concern varus stress radiographs are also indicated as they have been shown to be capable of making the diagnosis of a lateral soft tissue injury in the absence of MRI or ultrasound through measurement of lateral compartment gapping, as well as distinguish the severity of LCL and PLC injury [16].

Practically speaking, while MRI shows very detailed anatomy, stress x-rays show how the ligament is functioning compared to the other knee. By putting a force that should be controlled by the LCL on both knees, a surgeon can determine how well the ligament is functioning and thus, if a tear is functionally partial or complete. This is critical in determining if surgery will be needed.

Treatment:

LCL Injury treatment is determined by the severity of the injury and can range from mild interventions to surgical repair. Initial treatment is icing, compression, analgesics, and knee immobilization along with activity reduction/modification. Icing should be restricted to 15-minute intervals and applied indirectly to reduce the chance of cold injury to the peroneal nerve [10]. Activities with pivoting or cutting movements should be restricted, along with any other high impact activities or those that cause pain. LCL injuries are tricky, and if there is suspicion it is generally best managed by an orthopedist experienced in treatment of knee injuries as left untreated this initially mild appearing in jury can have significant long term consequences [10].

Treatment guidelines are as follows:

• - Grade 1: Non-operative treatment. Use hinge brace while weight bearing for 4-5 weeks. May add crutches for up to the first week to aid with pain control.
• - Grade 2: Non-operative treatment. Patient is required to be non-weight bearing on the knee with the use of crutches and a knee immobilizer for one to three weeks. Followed by progression to partial weight bearing with the use of a hinge brace during weeks two to three.

Both grade 1 and 2 injuries may be treated with rehabilitation exercises, starting with light range of motion movements, progressing to isometric strength exercises, and finally isotonic strength exercises and light aerobic activity. Injuries which fail to progress or show signs of worsening after four weeks should be referred to an orthopedic surgeon.

• - Grade 3: Operative treatment. Patient placed in knee immobilizer and is non-weight bearing with crutches until surgery can be performed, ideally within two weeks of the initial injury. Recent studies measuring surgical outcomes of LCL repairs show Intrasubstance LCL repairs have proven unsuccessful; with reconstructive surgeries recommended instead. In isolated LCL injuries, reconstruction is preferred using a semitendinosus autograft [15]. In an observational study performed by Moulton et al. in 2015, reconstructive surgery was associated with significant improvement in knee function and high patient satisfaction regarding their overall treatment and recovery [15].

Healing and recovery times will vary between individuals, but general criteria that should be met before returning to work or sport are set forth as:

1. Full motion of knee without pain
2. Quadriceps and hamstring strength is at least 90% of that of the unaffected lower extremity
3. Absence of tenderness of the injured structures
4. Absence of joint laxity
5. Able to complete functional activities which have similar demands to those of sport or work without pain.

Citations:

1. Recondo JA, Salvador E, Villanúa JA, Barrera MC, Gervás C, Alústiza JM. Lateral stabilizing structures of the knee: functional anatomy and injuries assessed with MR imaging. Radiographics. 2000;20 Spec No:S91-S102.
2. Lim HC, Bae JH, Bae TS, Moon BC, Shyam AK, Wang JH. Relative role changing of lateral collateral ligament on the posterolateral rotatory instability according to the knee flexion angles: a biomechanical comparative study of role of lateral collateral ligament and popliteofibular ligament. Arch Orthop Trauma Surg. 2012;132(11):1631-1636.
3. Swenson DM, Collins CL, Best TM, Flanigan DC, Fields SK, Comstock RD. Epidemiology of knee injuries among U.S. high school athletes, 2005/2006-2010/2011. Med Sci Sports Exerc. 2013;45(3):462-469.
4. Swenson DM, Collins CL, Best TM, Flanigan DC, Fields SK, Comstock RD. Epidemiology of knee injuries among U.S. high school athletes, 2005/2006-2010/2011. Med Sci Sports Exerc. 2013;45(3):462-469.
5. Chappell TM, Panchani PN, Moore GD, et al. Morphometry of the fibular collateral ligament: anatomic study with comprehensive review of the literature. Clin Anat. 2014;27(7):1089-1096.
6. LaPrade RF, Ly TV, Wentorf FA, Engebretsen L. The posterolateral attachments of the knee: a qualitative and quantitative morphologic analysis of the fibular collateral ligament, popliteus tendon, popliteofibular ligament, and lateral gastrocnemius tendon. Am J Sports Med. 2003;31(6):854-860.
7. Shetty A, Prabhath S, Alappatt K, Krishna Kn L, Bhat N, Sumalatha S. Lateral collateral ligament and anterolateral ligament of the knee - A morphological analysis with orthopedic significance. Knee. 2021;28:202-206.
8. Grawe B, Schroeder AJ, Kakazu R, Messer MS. Lateral Collateral Ligament Injury About the Knee: Anatomy, Evaluation, and Management. J Am Acad Orthop Surg. 2018;26(6):e120-e127.
9. Levy BA, Stuart MJ, Whelan DB. Posterolateral instability of the knee: evaluation, treatment, results. Sports Med Arthrosc Rev. 2010;18(4):254-262.
10. LaPrade RF, Wentorf F. Diagnosis and treatment of posterolateral knee injuries. Clin Orthop Relat Res. 2002;(402):110-121.
11. LaPrade RF, Terry GC. Injuries to the posterolateral aspect of the knee. Association of anatomic injury patterns with clinical instability. Am J Sports Med. 1997;25(4):433-438.
12. Lee J, Papakonstantinou O, Brookenthal KR, Trudell D, Resnick DL. Arcuate sign of posterolateral knee injuries: anatomic, radiographic, and MR imaging data related to patterns of injury. Skeletal Radiol. 2003;32(11):619-627.
13. LaPrade RF, Gilbert TJ, Bollom TS, Wentorf F, Chaljub G. The magnetic resonance imaging appearance of individual structures of the posterolateral knee. A prospective study of normal knees and knees with surgically verified grade III injuries. Am J Sports Med. 2000;28(2):191-199.
14. Sekiya JK, Swaringen JC, Wojtys EM, Jacobson JA. Diagnostic ultrasound evaluation of posterolateral corner knee injuries. Arthroscopy. 2010;26(4):494-499.
15. Moulton SG, Matheny LM, James EW, LaPrade RF. Outcomes following anatomic fibular (lateral) collateral ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2015;23(10):2960-2966.
16. LaPrade RF, Heikes C, Bakker AJ, Jakobsen RB. The reproducibility and repeatability of varus stress radiographs in the assessment of isolated fibular collateral ligament and grade-III posterolateral knee injuries. An in vitro biomechanical study. J Bone Joint Surg Am. 2008;90(10):2069-2076.

If you would like to have additional information on knee treatments or would like to learn more about LCL reconstruction, please contact Dr. Gilmer, serving the communities of Reno, NV.