Meniscal and Ligamentous Injuries of the Knee

Abstract

Meniscal and ligamentous injuries of the knee are common in patients of all ages or demographics. Many patients seek initial care after a knee injury from their primary care physician; thus, knowledge of the diagnosis and treatment of musculoskeletal injuries affecting the knee is important. The clinical presentation, physical examination, treatment modalities, and outcomes for meniscal and ligamentous pathology such as anterior cruciate ligament (ACL) injuries are discussed in the following chapter.

The Meniscus

The meniscus is a c-shaped fibrocartilaginous structure that lies between the femur and tibia on the medial and lateral aspects of the knee (Fig. 18.1). The meniscus serves as a cushion by absorbing the impact of weight-bearing forces, preventing bone-on-bone contact between the femoral condyle and tibial plateau. The meniscus is an important structure for both load bearing and stability of the knee joint.

Fig. 18.1

The anatomy of the knee joint

Summary of Epidemiology

Meniscal injuries are a common source of knee pain and can occur in traumatic or nontraumatic settings. Traumatic meniscal tears most frequently occur in young and active individuals aged 15–45. Over a third of traumatic meniscal tears are related to cutting and pivoting motions in sporting activities. Nontraumatic or degenerative meniscal tears most frequently present in older individuals, aged 45–70, and are often associated with osteoarthritis (OA). Individuals with a higher body mass index (BMI) have a greater occurrence of degenerative meniscal injury due to increased weight-bearing forces on the knee. In addition, medial meniscal tears are more common than lateral meniscal tears .

Clinical Presentation

Traumatic Meniscal Tears

Traumatic meniscal injuries are common injuries within the young and active population causing pain, loss of motion, and limitations in function. Common mechanisms of injury are noncontact decelerations including cutting and pivoting movements. These mechanisms of injury can be quite traumatic to the knee joint, and often there is a concomitant ligamentous injury. Traumatic meniscal tears commonly present with an effusion, pain, mechanical symptoms such as a locking or catching sensation, or a feeling of instability if a ligamentous injury is also involved. After an incident or event of the type described above, patients often have an immediate onset of pain that prevents them from continuing the activity or sport. Pain is localized to either the medial or lateral joint line, depending on the location of the tear. However, pain can be diffuse if a concurrent ligamentous injury is present. Individuals with a traumatic meniscal tear may report inability to fully flex or extend the knee because it is “stuck.” A mechanical block with significant functional limitations may occur when the flipped edge of a torn meniscus catches between the femoral condyle and tibial plateau .

Degenerative Meniscal Tears

Degenerative meniscal tears can be difficult to diagnose because of vague or variable symptoms in addition to the presence of concomitant osteoarthritis in the knee. Not all degenerative meniscal tears are symptomatic, and patients typically do not report any history of specific trauma or injury to the knee. Patients often describe a gradual onset of pain and symptoms associated with an active lifestyle. An effusion may or may not be present at the time of clinical presentation, although many patients report a history of swelling after an increase in activity level or duration of exercise. Degenerative meniscal tears typically present with pain and point tenderness localized to the posterior aspect of the medial or lateral joint line, depending on the location of the tear. Mechanical symptoms such as catching and locking are not always present. Instead, the chief complaint may be activity limitation secondary to pain .

Physical Examination

Physical examination and evaluation of knee pain starts with a thorough patient history. It is important to gather information on whether the knee pain occurred in a traumatic versus nontraumatic setting and the specific mechanism of injury. A proper physical examination includes inspection, palpation, range of motion, and specific tests for the suspected meniscal injury. The clinician should inspect both the affected and unaffected knee for effusion and bruising or discoloration. Determine if there is any tenderness along the medial and lateral joint lines. This is the most sensitive test for a meniscal tear. Perform a ballottement test by placing one hand above the patella and the other hand below the patella and pushing inward with both hands to check for fluid in the knee, and compare it to the contralateral side.

The range of motion should be assessed with the patient supine on an examination Table. A normal finding for range of motion is 0 degrees of extension and 135 degrees of flexion.

The McMurray test should be performed as part of a standard physical examination of the knee. The McMurray test is performed with the patient lying supine and the knee flexed to approximately 90° (Fig. 18.2). The examiner should have one hand over the joint line with the fingers placed on the medial joint line and the thumb placed on the lateral joint line. The other hand is placed at the heel of the foot (Fig. 18.2a). To test for a medial meniscal injury, the examiner should rotate the tibia externally, applying valgus stress to the knee, and twist the heel in an attempt to impinge any unstable torn edges of the meniscus (Fig. 18.2b). The presence of a lateral meniscal injury should be tested by rotating the tibia internally, applying varus stress to the knee, and twisting the heel in a similar fashion (Fig. 18.2c, d). A positive McMurray test is a “click” felt by the examiner along the joint line. However, a pseudo-positive test may not elicit a click, but rather pain with the motion. The sensitivity of the McMurray test is varied in the literature; one study reported a sensitivity of 50% on the medial side and 21% on the lateral side in 121 patients with meniscal injuries. Another study noted that a positive McMurray sign is indicative of good postoperative outcomes in patients with a meniscal lesion and concomitant osteoarthritis. Another examination for meniscal injury is the deep squat test. The examiner should have the patient bend into a deep squat where the knee is loaded and flexed past 90°. This allows the examiner to determine any pain coming from the meniscus as a deep squat may cause an impingement of the posterior horn of the meniscus against the femoral condyle. However, if the patient has an acute onset of injury and a large effusion, he or she may not be able to perform the deep squat test.

Fig. 18.2

McMurray test for meniscal tears . The examiner should place one hand on the joint line and the other hand around the ankle or heel (a). To test the medial meniscus, the examiner should rotate the lower leg externally (b). For the lateral meniscus, the examiner should rotate the lower leg internally (c, d)

Suggested Imaging

All patients presenting with traumatic or persistent knee pain should have plain radiographs obtained. Anterior-posterior, lateral, sunrise, and bilateral weight-bearing views should be obtained to rule out presence of a fracture or bony pathology. Radiographs can be helpful in identifying osteoarthritis, which is associated with a degenerative meniscal tear.

Magnetic resonance imaging (MRI) is particularly useful in patients with minimal or no knee osteoarthritis. An MRI should be considered in the presence of an acute onset of knee pain or persistent pain that limits daily activities and has failed conservative treatment measures. A systematic review by Oei et al. (2003) of 29 articles indicated that MRI had a sensitivity of 93.3% for a medial meniscal tear and 79.3% for a lateral meniscal tear. The specificity was 88.4% and 95.7% for medial and lateral meniscal tears, respectively. MRI is highly effective in determining the specific type, size, and location of a meniscal tear, especially when planning surgical intervention .

Non-operative Management

Not all meniscal injuries require surgical intervention, and many degenerative meniscal tears that are not impinging significantly between the femur and tibia can be managed non-operatively. If a diagnosed meniscal injury is suspected, but it is not causing significant mechanical symptoms or limitations, non-operative management should be considered. It is important for the patient to understand that degenerative meniscal tears rarely extend to the vascular component of the meniscus and therefore have poor healing potential. Non-operative modalities such as physical therapy , regular use of ice and NSAIDS, and corticosteroid injections can help to alleviate the symptoms of a chronic degenerative meniscal tear. Physical therapy to maximize proximal musculature strength reduces the weight-bearing forces on the knee and can improve symptoms. An ice and NSAID regimen can help to alleviate swelling and provide pain relief. Symptomatic episodes with swelling and pain can be treated with an intra-articular corticosteroid injection, often allowing the patient to continue physical therapy or home exercise programs .

Outcomes of Conservative Treatment Measures

Traumatic Meniscal Tears

Traumatic meniscal tears tend to occur in patients under the age of 30 and often cannot be managed effectively with conservative treatments. These tears usually cause swelling and limitation not only of athletic activities but also of activities of daily living. In a bucket-handle meniscal tear, a flipped piece of meniscal tissue causes a mechanical block, preventing the patient from fully extending or flexing their knee. These tears generally do not respond to conservative measures and require prompt evaluation, reduction, and surgical repair .

Degenerative Meniscal Tears

Physical therapy or structured exercise programs can be successful in reducing symptoms and improving function from chronic degenerative meniscal tears. Several studies published in the last few years that compared surgical intervention versus non-operative strengthening exercises in patients with degenerative medial meniscal tears showed that both the operative and non-operative groups had significant pain relief and improved function at 2-year follow-up. Another study (Neogi et al. 2013) of patients with degenerative medial meniscal tears showed that a 6-week course of analgesics combined with a formal exercise program provided pain relief and improved function up to 6 months after initial diagnosis, but benefits began to decline. The study found that osteoarthritis continued to progress and was associated with worse outcomes in the long term. Current literature suggests an initial non-operative treatment protocol consisting of analgesics and a formal or home exercise program before considering surgical intervention in the treatment of chronic degenerative meniscal tears .

Indications for Surgical Intervention

Patients presenting with a traumatic meniscal injury with pain, mechanical symptoms, and an MRI confirming a torn edge of the meniscus may require surgical intervention. Bucket-handle-type meniscal injuries necessitate surgical intervention to reduce the flipped meniscus and restore range of motion. Bucket-handle tears are often amenable to suture repair, unlike the majority of other meniscal tears. These tears are commonly associated with a ligamentous injury, such as an anterior cruciate ligament (ACL) tear . Bucket-handle tears are best repaired surgically in a timely fashion to preserve as much meniscal tissue as possible.

For degenerative meniscal tears, surgery may be indicated if non-operative modalities such as physical therapy or corticosteroid injections have failed. Patients with degenerative meniscal tears who have persistent mechanical symptoms with no or minimal osteoarthritis may elect arthroscopic surgery in order to debride the unstable edge of the meniscus. Degenerative meniscal tears are often associated with some degree of OA. Therefore, it is important that patients understand that the symptoms of OA will not be alleviated with an arthroscopic surgery ; however, any pain coming from a meniscal tear can be improved.

Operative Management

If surgery is indicated, patients will undergo an arthroscopic meniscal repair or meniscectomy . Arthroscopic surgery is performed through two small incisions—one anteromedial and one anterolateral—each measuring approximately 5 mm. An arthroscopic camera is first introduced into the knee joint in order to perform a diagnostic arthroscopy and assess the size and location of the meniscal tear (Fig. 18.3a, b). In addition, any degenerative changes to the cartilage or any ligamentous injury are also noted. The surgeon will evaluate the shape and size of the meniscal injury and determine if the meniscus can be repaired instead of debrided. An acute bucket-handle-type tear may be reparable. Arthroscopic meniscal repair involves the passing of a suture through the meniscus at the location of the tear to re-approximate the torn edges. Complex degenerative meniscal tears are irreparable and a partial meniscectomy is the appropriate intervention. In partial meniscectomy, an arthroscopic shaver is used to debride the torn and unstable edges, leaving behind the healthy and stable meniscal tissue .

Fig. 18.3

Arthroscopic image of healthy meniscal tissue (a). Arthroscopic image of a meniscal tear occurring in a traumatic setting (b)

Expected Outcome

Surgical Intervention for Traumatic Meniscal Tears

Patients who have undergone a meniscal repair to treat a traumatic meniscal tear face a 4–6-month rehabilitation period before returning to sport or other recreational activity. A recent systematic review by Moulton et al. (2016) showed satisfactory healing of the meniscus and satisfactory patient-reported outcomes up to 71 months after a repair for a radial meniscal tear. It is thought that preserving meniscal tissue by using repair techniques instead of debridement provides better long-term outcomes in young patients since, with a repair, the meniscus can continue to maximize its anatomic function in weight-bearing. However, long-term data remains limited.

Expected Outcome for Degenerative Meniscal Tears

Conservative treatment measures provide adequate pain relief and improvement in function for most people with degenerative meniscal tears. However, patients who fail non-operative modalities may elect arthroscopic intervention to treat a symptomatic degenerative meniscal tear. The efficacy of an arthroscopic partial meniscectomy has been brought into question with a 2013 randomized, double-blind, and sham-controlled trial by Sihvonen et al. (2013) involving 146 patients with degenerative medial meniscal tears and no evidence on plain films of osteoarthritis. The study showed that at 12 months, there was no significant difference between the group who underwent a partial medial meniscectomy and the group who underwent a sham surgery. In contrast to these findings, however, a recent study by Gauffin et al. (2014) evaluated 150 patients aged 45–64 with degenerative medial meniscal tears and no evidence of osteoarthritis on radiographs. Patients who underwent arthroscopic partial medial meniscectomy had substantially more improvement in pain than those having non-operative therapy. Katz et al. (2013) randomized 351 symptomatic patients with a meniscal tear and concomitant mild-to-moderate osteoarthritis to a standardized physical therapy regimen or arthroscopic surgery with postoperative physical therapy. The investigators found no significant differences in the study groups in patient-reported outcomes at both 6 and 12 months after randomization. Of note, 30% of the patients who were randomized into the conservative treatment with physical therapy group elected to undergo surgery within 6 months of randomization. There are inconsistencies in the literature on the efficacy of surgical intervention for a degenerative meniscal tear, precluding definitive recommendations. The body of evidence does suggest that physical therapy should be the first line of treatment and that a partial meniscectomy remains a potential treatment for those with persistent pain and functional limitation despite a full complement of conservative treatments. It is important for patients to understand that the surgery will not alleviate symptoms from early concomitant osteoarthritis in the knee .

Ligamentous Injury

The knee is comprised of four major ligaments, each of which contributes to stability of the knee joint during movement. The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are located in the intercondylar notch. The ACL stabilizes anterior tibial translation, while the PCL stabilizes posterior tibial translation. The medial collateral ligament (MCL) is located on the medial aspect of the knee and connects the tibia and femur to prevent any medial translation of the tibia. The lateral collateral ligament (LCL) is located on the lateral aspect of the knee and prevents lateral translation of the tibia (Fig. 18.1). All four ligaments work together to stabilize all planes of motion during weight-bearing activities.

Summary of Epidemiology

Ligamentous injury is a common injury to the knee during more demanding activities such as cutting, pivoting, or twisting. The ACL and MCL are the most commonly injured ligaments in the knee. It is estimated that over 200,000 ACL injuries occur annually in the United States, the majority occurring in sports that involve cutting and pivoting movements such as soccer, basketball, skiing, and football. Injuries to the ACL are most prevalent in young and active patients aged 15–45. Females are 2–8 times as likely as their male counterparts to sustain ACL injury due to anatomical and biomechanical differences that place additional stress on the knee. MCL injuries also frequently occur in young and active patients who play sports that involve valgus stress, such as soccer, basketball, ice hockey, and football. MCL injuries such as sprains and partial tears are more prevalent than complete ruptures. PCL and LCL injuries can and do occur but are far less common than ACL and MCL injuries.

Clinical Presentation

Anterior Cruciate Ligament Injury

ACL injuries have become increasingly prevalent among the young and active population and cause pain, swelling, mechanical symptoms, and instability. The majority of ACL injuries occur during a sport or physical activity that involves quick changes of direction. Common sports or activities associated with a high incidence of ACL tears include soccer, basketball, football, skiing, and lacrosse. The mechanism of most ACL injuries is noncontact. Many patients will describe an attempted cut, pivot, or landing from a jump in which their knee subsequently “gave out.” One of the hallmark descriptions of an ACL tear is a noncontact valgus stress, followed by an audible or felt “pop” in the knee. Some patients may describe a contact mechanism with hyperextension or player contact with the knee bending inward into valgus stress. Most patients have an immediate onset of pain and swelling and are not able to continue activity. Acute ACL injuries will often present to clinic with a large effusion, loss of motion, pain, and anterior instability. Some patients are not able to weight bear at all after an ACL injury, others are able to ambulate with difficulty, and some are able to ambulate but feel overt instability. The mechanism of injury for ACL tears, a rotational force, valgus stress, or hyperextension, can also be associated with injuries to the meniscus or MCL.

Medial Collateral Ligament Injuries

MCL injuries are another common knee injury and occur more frequently from a contact mechanism. A strong contact force to the outside of the knee that causes the knee to move inward into a valgus position puts stress on the MCL, causing a strain or tear. MCL injuries commonly result in a partial tear or strain rather than a full-thickness tear or avulsion from the attachment site. A strain may present with pain localized to the inner aspect of the knee with minimal swelling and no instability. Partial tears may present with moderate to severe pain, a sense of instability, and some swelling. Full-thickness tears often relate to severe pain, instability, loss of range of motion, and a large effusion .

Posterior Cruciate Ligament

PCL injuries are significantly less common than ACL injuries and may go unrecognized. Anatomically, the PCL is more robust and stronger than the ACL. The most common mechanism of injury for PCL tears is a strong force to the anterior aspect of the knee while the knee is flexed. For example, a flexed knee hitting the dashboard in a motor vehicle accident often results in a PCL injury. In more demanding activities such as sports, a force on the anterior aspect of the knee with hyperextension can also cause an avulsion injury to the PCL .

Lateral Collateral Ligament

Injuries to the LCL are significantly less common than MCL injuries. The mechanism of injury is a strong contact force on the inside of the knee that causes excessive varus stress on the LCL, causing it to strain or tear. Like injuries to the MCL, LCL injuries can range from a strain to a full-thickness tear. Presentation depends on the severity of the injury. Patients may present with a range of symptoms, from localized pain to the outermost aspect of the knee (in a strain or low-grade partial thickness tear) to loss of range of motion and functional limitations (in a full-thickness tear).

Physical Examination

Anterior and Posterior Cruciate Ligaments

A thorough patient history is essential in order to determine what structure has been injured. For ACL injury, a specific incident or event is usually associated with the onset of knee pain. Many patients feel or hear a “pop” in the knee followed by extreme pain, immediate swelling, and inability to continue physical activity.

Inspect both the affected and contralateral knee for bruising or discoloration and obvious swelling. Determine if fluid is present in the suprapatellar pouch or knee joint by performing a ballottement test. Check for point tenderness; an isolated ACL injury may have diffuse tenderness, while an ACL injury combined with a collateral ligament or meniscal injury may be point tender over the medial or lateral joint line. Test for range of motion on both the affected and contralateral knee to assess a baseline measurement (0–135°). Patients with a suspected ACL injury may have limitations in extension and flexion with moderate to severe pain.

The Lachman test is the most sensitive clinical examination test for ACL tears and measures the degree of anterior tibial translation. A proper Lachman is performed with the knee at approximately 30 degrees of flexion and slightly externally rotated. The examiner should place one hand around the patient’s thigh approximately 3–5 cm above the patella and the other hand around the tibia with the thumb placed directly on the tibial tuberosity (Fig. 18.4a). The examiner should pull the tibia anteriorly while simultaneously pushing down on the thigh to assess anterior tibial translation. The Lachman test should first be performed on the contralateral knee to determine baseline tibial translation. A positive Lachman is characterized by increased anterior tibial translation on the injured knee and is highly predictive of a torn ACL.

Fig. 18.4

Knee position and examiner hand placement for the Lachman (a). Knee position and hand placement for the anterior drawer and posterior drawer (b)

Another specific test for instability of the knee is the anterior drawer, which similarly assesses anterior tibial translation. The anterior drawer is performed while the knee is flexed 90° with the examiner’s thumbs on the anteromedial and anterolateral joint lines (Fig. 18.4b). The examiner should stress the tibia anteriorly while keeping the thumbs steady on the joint line to determine the amount of translation. The anterior drawer should also be assessed on the contralateral side for a baseline measurement. An anterior drawer resulting in increased anterior tibial translation is also predictive of an ACL tear. The posterior drawer test assesses posterior tibial translation and is sensitive to PCL injury. In a position similar to the anterior drawer test, the knee is flexed to about 90° with both thumbs placed on the anteromedial and anterolateral joint lines (Fig. 18.4b). The tibia is stressed posteriorly, while the examiner feels for any increase in translation compared to the contralateral side. Any increased posterior tibial translation is indicative of a PCL tear.

Medial and Lateral Collateral Ligaments

A thorough patient history should first be obtained. The description of the mechanism of injury is important to determine what ligament may be affected. MCL injuries are common with excessive valgus stress on the knee after contact to the outside of the knee. An LCL injury can be suspected if a patient describes a contact mechanism or varus force to the inside of the knee. Inspection, palpation, and range of motion should be performed for every suspected knee injury as described in the anterior and posterior cruciate ligament physical examination section.

The examiner should palpate for point tenderness on the medial or lateral joint line and apply pressure along the native location of the MCL or LCL, from femoral insertion to tibial insertion. Patients with injury to the MCL or LCL will feel pain and point tenderness along the ligament, not solely confined to the joint line. Point tenderness along the native MCL or LCL is a strong indication of injury.

The valgus stress test is useful for determining a partial or complete tear of the MCL. The patient should lie supine, with their knee flexed approximately 20–30°. The examiner should place their fingers over the joint line. A valgus stress is applied to the foot and ankle, and the amount of medial compartment opening or gapping is measured. The severity of an MCL injury (grades I–IV) can be determined by the amount of gapping upon valgus stress.

The varus stress test is used to determine the integrity of the LCL. The patient should lie supine with their knee flexed approximately 20–30°. The examiner should have their fingers over the joint line, and the distal femur stabilized. A varus stress is applied through the foot and ankle, and the amount of lateral compartment opening or gapping is measured. The severity of an LCL injury (grades I–IV) can be determined by the amount of gapping upon varus stress.

Diagnostic Imaging

Plain radiographs, including anterior-posterior, lateral, sunrise, and bilateral weight-bearing views, should be obtained to rule out evidence of fracture or bony pathology. For example, a Segond fracture is a small avulsion fracture of the lateral aspect of the tibia that is frequently associated with ACL injury. MRI is the gold standard for determining a ligamentous injury, as well as concurrent meniscal and cartilage injuries (Fig. 18.5a, b).

Fig. 18.5

MRI showing a healthy ACL (a) and a full-thickness ACL tear (b)

Non-operative Management

Anterior Cruciate Ligament

Patients with a torn ACL may be managed non-operatively or choose to have an ACL reconstruction. The majority of patients who participate in sports and are younger than the age of 35 opt for surgical reconstruction. However, ACL reconstruction is not for every patient. Patients with moderate to severe osteoarthritis are not candidates for ACL reconstruction as it can exacerbate arthritic pain. It is important to convey to the patient the function and purpose of the ACL and that a torn ACL will not impact forward or backward movements such as jogging or walking. Patients who are not as active and do not regularly participate in cutting and pivoting activities may have success with non-operative management. A formal course of physical therapy to reduce swelling and maximize proximal musculature strength often allows for the desired quality of life. Patients can also be fit for a functional ACL brace that provides added stability in cutting and pivoting activities such as tennis or skiing.

Outcomes of Non-operative Management for ACL Injury

Several studies have compared the outcomes of operative versus non-operative management for ACL injuries. Ericsson et al. (2013) compared physical performance and muscle strength between non-operative and operative treatments following an acute ACL tear and found no difference between the groups at 2- and 5-year follow-up. This study has provided evidence that non-operative treatment modalities can be an adequate treatment for ACL injury. Patients who are ACL deficient may be at risk for future instability episodes and subsequent injuries, causing a progression of osteoarthritis or further damage to the meniscus and cartilaginous structures of the knee. Sanders et al. (2016) showed that individuals who were treated non-operatively for an ACL injury had a significantly higher risk of secondary meniscal tear and osteoarthritis. However, it is ultimately the patient’s preference in the decision to manage an ACL injury operatively or non-operatively. Younger, adolescent patients and those who wish to participate in heavy cutting and pivoting activities may wish to undergo a reconstruction for knee stabilization in physically demanding activities.

Medial and Lateral Collateral Ligament

The majority of collateral ligament injuries are strains and partial tears that should be managed non-operatively. Patients who have a strain or partial tear of the collateral ligament can undergo a formal course of physical therapy to reduce swelling, relieve symptoms, and increase proximal musculature strength. Formal physical therapy can alleviate symptoms and return the patient to activity after injury. Patients who have persistent instability when ambulating or participating in cutting or pivoting activities can be fit with a functional brace to provide added stability.

Non-operative management of ligamentous injuries can result in good outcomes with appropriate rehabilitation (physical therapy), use of a functional brace as indicated, and limitation of cutting and pivoting at-risk activities. The inherent laxity in non-operatively managed knees does increase the risk for additional injury, as recurrent episodes of instability can cause further damage to other ligaments, meniscus, or cartilage, as well as increasing the risk for early osteoarthritis .

Indications for Surgery

ACL or PCL reconstruction is indicated for young and active individuals who are unable to participate in their desired activities due to instability or pain in the knee with activities. ACL injuries are often indicated for surgical reconstruction in contrast to isolated PCL injuries, the majority of which are managed non-operatively. Knee dislocations resulting in multi-ligament injuries usually necessitate surgical intervention.

Patients with a full-thickness MCL or LCL tear who have recurrent feelings of instability or pain that limit their desired activity level may be candidates for an MCL or LCL reconstruction. While most MCL or LCL tears are treated non-operatively, full-thickness tears that do not improve with non-operative modalities should be considered for surgical reconstruction .

Operative Management

Anterior Cruciate Ligament Reconstruction

Arthroscopic ACL reconstruction is performed with small 5–10 mm incisions located on the anteromedial and anterolateral aspects of the anterior knee. An ACL can be reconstructed with the use of an autograft or allograft. Most commonly, autografts are used from the patellar tendon or hamstring tendons (semitendinosus and gracilis). An ACL reconstruction is performed first by debriding the torn fibers of the ACL and addressing any other concurrent meniscal or ligamentous injuries (Fig. 18.6a, b). After the graft has been prepared, a drill is used to create a tunnel for the graft on both the femoral and tibial sides. The reconstructed ACL graft is introduced into the joint and fixated with an interference screw or suture button on both the femoral and tibial sides. A PCL reconstruction follows a similar procedure. MCL and LCL reconstructions are fixated on the femoral and tibial sides with an interference screw, EndoButton, or suture button.

Fig. 18.6

Arthroscopic image of a ruptured ACL in the intercondylar notch (a). Arthroscopic image of a newly reconstructed ACL with hamstring autograft (b)

Expected Outcomes of Surgical Intervention

Patients undergoing a ligament reconstruction should expect a rehabilitation period of 6 months. The newly reconstructed ligament takes approximately 3 months to heal into the bone, and rehabilitation is controlled until that point. Patients are often managed in a hinged brace and may or may not utilize crutches for ambulation for the first 2–6 weeks. After 3 months, patients focus on regaining strength and function so that they may begin to resume their desired activities at 6 months.

ACL injuries have become far too common, especially in adolescent athletes, and youth prevention programs have been developed to reduce biomechanical risk factors. Fortunately, short-term outcomes from an ACL reconstruction are generally successful, with return to activity and relief of pain and instability symptoms after rehabilitation is complete. In the young athlete under 14 years of age, Chicorelli et al. (2016) found that 96% of athletes were able to return to sporting activity, and 85% were able to return to sport within 12 months postoperatively. Studies of NCAA Division I football players and NCAA Division I soccer athletes who underwent ACL reconstruction had return to play rates of around 85%. Rate of return to play is generally higher in recreational athletes.

Unfortunately, ACL reconstructions do not prevent the potential long-term consequences such as the early development of osteoarthritis 10–20 years after the procedure. A study of 135 patients with diagnosed ACL injuries (Barenius et al. 2014) found that the prevalence of osteoarthritis was three times higher in the group treated with a reconstruction at 14-year follow-up. The group also found that concomitant meniscal resection further increased the risk of OA. A systematic review by Oiestad et al. (2009) reported that osteoarthritis occurs in up to 13% of patients with an isolated ACL injury and reconstruction and in 21–48% of patients with concomitant injuries. The likelihood of osteoarthritis increases in patients with combined ACL and meniscal injuries, highlighting the importance of both structures in long-term knee function. Table 18.1 shows meniscal and ligamentous injuries of the knee.

Table 18.1 Meniscal and ligamentous injuries of the knee