Unhappy triad
Encyclopedia
An unhappy triad is an injury to the anterior cruciate ligament, medial collateral ligament, and the meniscus. The triad refers to a complete or partial tear of the anterior cruciate ligament, medial collateral ligament, and the meniscus. Originally the "unhappy triad" included the medial meniscus
and not the lateral meniscus
. However, during the 1990's, analysis indicated that the 'classic' O'Donoghue triad is actually an unusual clinical entity among athletes with knee injuries. In this type of injury, acute tears of the medial meniscus always present with a concomitant lateral meniscus injury. However, the lateral meniscus tears are far more common than medial meniscus tears in sprains of the ACL.
In 1991, Shelbourne and Nitz questioned the validity of O’Donoghue’s terrible triad study. A review of all arthroscopically confirmed acute injuries of second degree or worse to the ACL and MCL was performed. Of the 52 knees reviewed, 80% of group 1 had lateral meniscus tears and 29% had associated medial meniscus tears. None of the medial meniscus tears were isolated; medial meniscus tears were not present in the absence of a lateral meniscus tear. From this study, it was concluded that the structures involved in the terrible triad were the anterior cruciate ligament, medial collateral ligament, and the lateral (not medial) meniscus.
No muscles are directly involved in this injury, only ligaments; However, strengthening the hip flexor and hip extensor muscles may help alleviate the injury.
The medial collateral ligament
, posterior cruciate ligament
, anterior cruciate ligament
, and lateral collateral ligament are the four primary ligaments of the knee. The medial and lateral collateral ligaments primarily provide support to varus
and valgus
forces whereas the anterior and posterior cruciate ligaments prevent anterior and posterior translation of the tibia
on the femur
.
, medial collateral ligament
,and meniscus
. Injury is most often sustained when a lateral (from the outside) force impacts the knee while the foot is fixed on the ground. The strong valgus or rotary force to the knee tears the ACL, MCL, and lateral meniscus all together. This type of injury occurs often in contact sports such as football, rugby, or motocross. During the injury, the leg is laterally rotated and over-abducted. In about 10% of cases the force is applied to the opposite side of the knee, and the lateral and posterolateral ligaments are torn.
and shoulder
.
The term "terrible triad" is also sometimes used in the popular press to describe conditions relating to pain, or even to refer to the MacDonald triad
of sociopathic behavior.
An associated medial collateral ligament tear was more common in skiing (22/30) than during contact sports (23/59), whereas a bicompartmental meniscal lesion was found more frequently in contact sports (9/59) than in skiing (0/30). Weightbearing was reported by 56/59 of the patients with contact sports injuries whereas 8/30 of those with skiing injuries. Non-weightbearing in the injury situation led to the same rate of MCL tears (18/28) as weightbearing (35/72) but significantly more intact menisci (19/28 vs 23/72). Thus, contact sports injuries were more often sustained during weightbearing, with a resultant joint compression of both femuro-tibial compartments as shown by the higher incidence of bicompartmental meniscal lesions. The classic "unhappy triad" was a rare finding (8/100) and Fridén T, Erlandsson T, Zätterström R, Lindstrand A, and Moritz U. suggest that this entity should be replaced by the "unhappy compression injury".
is one of the four crucial ligaments in the knee. It originates from the lateral condyle of the femur and goes to the intercondyloid eminence of the tibia. Its function is to provide stability in the knee and minimize stress across the knee joint. It also restrains excessive forward movement in the leg and limits rotational movements in the knee.
Anterior cruciate ligament tear:
Injury
An anterior cruciate ligament injury
results from excess tension the ligament. This can be done from a sudden stop or twisting motion of the knee. A few initial symptoms include swelling, knee instability, and pain. A popping sound or sensation may or may not be heard when the ACL first tears. A following symptom usually includes the feeling of the knee “giving out”. Tearing of the ACL is the most significant injury because it leaves the knee unstable, which also causes the knee to lose its normal function.
Epidemiology
It is estimated that 100,000 new anterior cruciate ligament injuries occur each year. Approximately half of the new ACL injuries involve injuries to the ligament, tendon, and or muscle of that affected knee. Women are at greater risk for ACL injuries than men due to their greater Q angle. The Q angle is the angle formed by a line drawn from the anterior superior iliac spine
to central patella and a second line drawn from central patella to tibial tubercle.
The medial meniscus
is a C-wedge shaped piece of cartilage that acts as “shock absorbers” between the femur and the tibia. Each knee has two menisci, one at the outer edge and one at the inner edge of the knee. The menisci are tough and rubber-like to help cushion the joint and help keep it stable.
The lateral meniscus
is also known as the external semilunar fibrocartilage. It is a fibrocartilage
band on the lateral side of the knee joint and can easily be injured with torsional stress or direct force.
Each knee has a medial and lateral meniscus
, which consist of connective tissue and collagen fibers. Meniscus is needed to distribute the body weight across the knee. Without the meniscus the body weight is distributed unevenly on the femur
and tibia
possibly leading to early arthritis to the knee joint. The meniscus is nourished by small blood vessels, but it has a large central section which is avascular and does not get direct blood supply. This poses a problem in a meniscus injury as blood flow is diminished and the avascular areas tend to not heal.
Injury
The tear of meniscus
is among the most common knee injuries. It is usually caused by torsional stress; twisting or turning of the knee too quickly with the foot planted on the ground while the knee is flexed. The feeling of a “pop” in the knee is usually felt when the meniscus is torn. Athletes, particularly those who participate in contact sports, are at a greater risk for meniscal tears. Sports-related meniscal tears often occur with other knee injuries, such as an anterior cruciate ligament tear.
A torn meniscus is commonly referred to as a torn cartilage in the knee. Menisci tear in different ways and are noted by how they look, as well as where the tear occurs in the meniscus. Two types of tears include minor, which includes stiffness and swelling within two to three days but usually goes away in two to three weeks. Then there is severe, which without treatment, a piece of meniscus may come loose and drift into the joint space. Tears include longitudinal, parrot-beak, flap, bucket handle, and mixed/complex. Image of meniscal tear
Epidemiology
Injury to the medial meniscus is about five times greater than injury to the lateral meniscus due to its anatomical attachment to the MCL. Lateral meniscal tears are more common in acute ACL injuries whereas medial mensical injuries are more common in chronic ACL deficient knees are more amenable to repair.
Meta-analysis shows that in acute injuries of the ACL associated with a meniscus tear 44% were of the medial meniscus whereas 56% were of the lateral meniscus; in chronic ACL insufficiency 70% were medial whereas 30% were lateral.
Because the medial collateral ligament
resists widening of the inside of the knee joint, the ligament is usually injured when the outside of the knee joint is struck. This force causes the outside of the knee to buckle, and the inside to widen. When the MCL is stretched too far, it is susceptible to tearing and injury. This is the injury seen by the action of "clipping" in a football game.
An injury to the MCL may occur as an isolated injury, or it may be part of a complex injury to the knee. Other ligaments ACL, or meniscus, may be torn along with a MCL injury
Symptoms
The most common symptom following an MCL injury is pain directly over the ligament. Swelling over the torn ligament may appear, and bruising and generalized joint swelling are common 1 to 2 days after the injury. In more severe injuries, patients may complain that the knee feels unstable
Treatment
Treatment of an MCL tear depends on the severity of the injury. Treatment always begins with allowing the pain to subside, beginning work on mobility, followed by strengthening the knee to return to sports and activities. Bracing can often be useful for treatment of MCL injuries. Fortunately, most often surgery is not necessary for the treatment of an MCL tear.
A typical surgery for a blown knee includes:
The goal of reconstruction surgery is to prevent instability and restore the function of the torn ligament, creating a stable knee. There are certain factors that the patient must consider when deciding for or against surgery.
Medial meniscus
-External links: *...
and not the lateral meniscus
Lateral meniscus
The lateral meniscus, also called the external semilunar fibrocartilage, is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular and covers a larger portion of the...
. However, during the 1990's, analysis indicated that the 'classic' O'Donoghue triad is actually an unusual clinical entity among athletes with knee injuries. In this type of injury, acute tears of the medial meniscus always present with a concomitant lateral meniscus injury. However, the lateral meniscus tears are far more common than medial meniscus tears in sprains of the ACL.
History
In 1936 Cambell stated that an “impairment of the anterior crucial and mesial ligaments is associated with injuries of the internal cartilage”. In 1950, O’Donoghue described the unhappy triad as: (1) rupture of the medial collateral ligament, (2) damage to the medial meniscus and (3) rupture of the anterior cruciate ligament. O’Donoghue estimated the incidence rate in the traumatic sports knee to be 25%.In 1991, Shelbourne and Nitz questioned the validity of O’Donoghue’s terrible triad study. A review of all arthroscopically confirmed acute injuries of second degree or worse to the ACL and MCL was performed. Of the 52 knees reviewed, 80% of group 1 had lateral meniscus tears and 29% had associated medial meniscus tears. None of the medial meniscus tears were isolated; medial meniscus tears were not present in the absence of a lateral meniscus tear. From this study, it was concluded that the structures involved in the terrible triad were the anterior cruciate ligament, medial collateral ligament, and the lateral (not medial) meniscus.
Skeletal and Muscle Elements Involved
Skeletal components involved in the unhappy triad include:- patella
- femurFemurThe femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
- tibiaTibiaThe tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
No muscles are directly involved in this injury, only ligaments; However, strengthening the hip flexor and hip extensor muscles may help alleviate the injury.
The medial collateral ligament
Medial collateral ligament
The medial collateral ligament of the knee is one of the four major ligaments of the knee. It is on the medial side of the knee joint in humans and other primates. It is also known as the tibial collateral ligament, or abbreviated as the MCL.- Structure :It is a broad, flat, membranous band,...
, posterior cruciate ligament
Posterior cruciate ligament
The posterior cruciate ligament is one of the four major ligaments of the knee. It connects the posterior intercondylar area of the tibia to the medial condyle of the femur...
, anterior cruciate ligament
Anterior cruciate ligament
The anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...
, and lateral collateral ligament are the four primary ligaments of the knee. The medial and lateral collateral ligaments primarily provide support to varus
Varus deformity
In orthopedics, a varus deformity is a term for the inward angulation of the distal segment of a bone or joint. The opposite of varus is called valgus.The terms varus and valgus always refer to the direction that the distal segment of the joint points....
and valgus
Valgus deformity
In orthopedics, a valgus deformity is a term for outward angulation of the distal segment of a bone or joint. The opposite deformation, medial deviation of the distal bone, is called varus....
forces whereas the anterior and posterior cruciate ligaments prevent anterior and posterior translation of the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
on the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
.
Structures in triad
The classic O'Donoghue triad is characterized by an injury to three knee structures:- the anterior cruciate ligamentAnterior cruciate ligamentThe anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...
- the medial collateral ligamentMedial collateral ligamentThe medial collateral ligament of the knee is one of the four major ligaments of the knee. It is on the medial side of the knee joint in humans and other primates. It is also known as the tibial collateral ligament, or abbreviated as the MCL.- Structure :It is a broad, flat, membranous band,...
(or "tibial collateral ligament") - the medial meniscusMedial meniscus-External links: *...
(however, lateral meniscusLateral meniscusThe lateral meniscus, also called the external semilunar fibrocartilage, is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular and covers a larger portion of the...
injuries are more commonly seen among athletes.)
Injury
The unhappy triad occurs due to a lateral blow to the knee causing a rupture in the anterior cruciate ligamentAnterior cruciate ligament
The anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...
, medial collateral ligament
Medial collateral ligament
The medial collateral ligament of the knee is one of the four major ligaments of the knee. It is on the medial side of the knee joint in humans and other primates. It is also known as the tibial collateral ligament, or abbreviated as the MCL.- Structure :It is a broad, flat, membranous band,...
,and meniscus
Meniscus
The meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the material of the...
. Injury is most often sustained when a lateral (from the outside) force impacts the knee while the foot is fixed on the ground. The strong valgus or rotary force to the knee tears the ACL, MCL, and lateral meniscus all together. This type of injury occurs often in contact sports such as football, rugby, or motocross. During the injury, the leg is laterally rotated and over-abducted. In about 10% of cases the force is applied to the opposite side of the knee, and the lateral and posterolateral ligaments are torn.
Terminology
The term "unhappy triad" was coined by O'Donoghue in 1950. However, since then, this term and the term "terrible triad" have also been used to describe several other combinations of joint injuries, including those of the elbowElbow
The human elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm....
and shoulder
Shoulder
The human shoulder is made up of three bones: the clavicle , the scapula , and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint, which...
.
The term "terrible triad" is also sometimes used in the popular press to describe conditions relating to pain, or even to refer to the MacDonald triad
Macdonald triad
The Macdonald triad is a set of three behavioral characteristics that are associated with sociopathic behavior. The triad was first identified by J.M...
of sociopathic behavior.
Symptoms
- Pain in affected knee
- Stiffness and swelling in affected knee
- Catching or locking of the knee in affected knee
- Instability of the knee with twisting or side-to-side movements(The sensation of the knee “giving out”).
- Inability to move the knee through its full range of motion
Epidemiology
A study containing 100 consecutive patients with a recent anterior cruciate ligament injury were examined with respect to type of sports activity that caused the injury. Of the 100 consecutive ACL injuries there were also, 53 medial collateral ligament injuries, 12 medial, 35 lateral and 11 bicompartmental meniscal lesions. 59/100 patients were injured during contact sports, 30/100 in downhill skiing and 11/100 in other recreational activities, traffic accidents or at work.An associated medial collateral ligament tear was more common in skiing (22/30) than during contact sports (23/59), whereas a bicompartmental meniscal lesion was found more frequently in contact sports (9/59) than in skiing (0/30). Weightbearing was reported by 56/59 of the patients with contact sports injuries whereas 8/30 of those with skiing injuries. Non-weightbearing in the injury situation led to the same rate of MCL tears (18/28) as weightbearing (35/72) but significantly more intact menisci (19/28 vs 23/72). Thus, contact sports injuries were more often sustained during weightbearing, with a resultant joint compression of both femuro-tibial compartments as shown by the higher incidence of bicompartmental meniscal lesions. The classic "unhappy triad" was a rare finding (8/100) and Fridén T, Erlandsson T, Zätterström R, Lindstrand A, and Moritz U. suggest that this entity should be replaced by the "unhappy compression injury".
The anterior cruciate ligament
The anterior cruciate ligamentAnterior cruciate ligament
The anterior cruciate ligament is a cruciate ligament which is one of the four major ligaments of the human knee. In the quadruped stifle , based on its anatomical position, it is referred to as the cranial cruciate ligament.The ACL originates from deep within the notch of the distal femur...
is one of the four crucial ligaments in the knee. It originates from the lateral condyle of the femur and goes to the intercondyloid eminence of the tibia. Its function is to provide stability in the knee and minimize stress across the knee joint. It also restrains excessive forward movement in the leg and limits rotational movements in the knee.
Anterior cruciate ligament tear:
Injury
An anterior cruciate ligament injury
Anterior cruciate ligament injury
An injury to the anterior cruciate ligament can be a debilitating musculoskeletal injury to the knee, seen most often in athletes. Non-contact tears and ruptures are the most common causes of ACL injury....
results from excess tension the ligament. This can be done from a sudden stop or twisting motion of the knee. A few initial symptoms include swelling, knee instability, and pain. A popping sound or sensation may or may not be heard when the ACL first tears. A following symptom usually includes the feeling of the knee “giving out”. Tearing of the ACL is the most significant injury because it leaves the knee unstable, which also causes the knee to lose its normal function.
Epidemiology
It is estimated that 100,000 new anterior cruciate ligament injuries occur each year. Approximately half of the new ACL injuries involve injuries to the ligament, tendon, and or muscle of that affected knee. Women are at greater risk for ACL injuries than men due to their greater Q angle. The Q angle is the angle formed by a line drawn from the anterior superior iliac spine
Anterior superior iliac spine
The anterior superior iliac spine is an important landmark of surface anatomy. It refers to the anterior extremity of the iliac crest of the pelvis, which provides attachment for the inguinal ligament, and the sartorius muscle...
to central patella and a second line drawn from central patella to tibial tubercle.
Meniscus
Medial meniscus
-External links: *...
is a C-wedge shaped piece of cartilage that acts as “shock absorbers” between the femur and the tibia. Each knee has two menisci, one at the outer edge and one at the inner edge of the knee. The menisci are tough and rubber-like to help cushion the joint and help keep it stable.
The lateral meniscus
Lateral meniscus
The lateral meniscus, also called the external semilunar fibrocartilage, is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular and covers a larger portion of the...
is also known as the external semilunar fibrocartilage. It is a fibrocartilage
Fibrocartilage
White fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its flexibility and toughness to the former of these constituents, and its elasticity to the latter...
band on the lateral side of the knee joint and can easily be injured with torsional stress or direct force.
Each knee has a medial and lateral meniscus
Lateral meniscus
The lateral meniscus, also called the external semilunar fibrocartilage, is a fibrocartilaginous band that spans the lateral side of the interior of the knee joint. It is one of two menisci of the knee, the other being the medial meniscus. It is nearly circular and covers a larger portion of the...
, which consist of connective tissue and collagen fibers. Meniscus is needed to distribute the body weight across the knee. Without the meniscus the body weight is distributed unevenly on the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
and tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
possibly leading to early arthritis to the knee joint. The meniscus is nourished by small blood vessels, but it has a large central section which is avascular and does not get direct blood supply. This poses a problem in a meniscus injury as blood flow is diminished and the avascular areas tend to not heal.
Injury
The tear of meniscus
Tear of meniscus
In sports and orthopedics, a tear of a meniscus is a rupturing of one or more of the fibrocartilage strips in the knee called menisci. When doctors and patients refer to "torn cartilage" in the knee, they actually may be referring to an injury to a meniscus at the top of one of the tibiae. Menisci...
is among the most common knee injuries. It is usually caused by torsional stress; twisting or turning of the knee too quickly with the foot planted on the ground while the knee is flexed. The feeling of a “pop” in the knee is usually felt when the meniscus is torn. Athletes, particularly those who participate in contact sports, are at a greater risk for meniscal tears. Sports-related meniscal tears often occur with other knee injuries, such as an anterior cruciate ligament tear.
A torn meniscus is commonly referred to as a torn cartilage in the knee. Menisci tear in different ways and are noted by how they look, as well as where the tear occurs in the meniscus. Two types of tears include minor, which includes stiffness and swelling within two to three days but usually goes away in two to three weeks. Then there is severe, which without treatment, a piece of meniscus may come loose and drift into the joint space. Tears include longitudinal, parrot-beak, flap, bucket handle, and mixed/complex. Image of meniscal tear
Epidemiology
Injury to the medial meniscus is about five times greater than injury to the lateral meniscus due to its anatomical attachment to the MCL. Lateral meniscal tears are more common in acute ACL injuries whereas medial mensical injuries are more common in chronic ACL deficient knees are more amenable to repair.
Meta-analysis shows that in acute injuries of the ACL associated with a meniscus tear 44% were of the medial meniscus whereas 56% were of the lateral meniscus; in chronic ACL insufficiency 70% were medial whereas 30% were lateral.
Medial Collateral Ligament
InjuryBecause the medial collateral ligament
Medial collateral ligament
The medial collateral ligament of the knee is one of the four major ligaments of the knee. It is on the medial side of the knee joint in humans and other primates. It is also known as the tibial collateral ligament, or abbreviated as the MCL.- Structure :It is a broad, flat, membranous band,...
resists widening of the inside of the knee joint, the ligament is usually injured when the outside of the knee joint is struck. This force causes the outside of the knee to buckle, and the inside to widen. When the MCL is stretched too far, it is susceptible to tearing and injury. This is the injury seen by the action of "clipping" in a football game.
An injury to the MCL may occur as an isolated injury, or it may be part of a complex injury to the knee. Other ligaments ACL, or meniscus, may be torn along with a MCL injury
Symptoms
The most common symptom following an MCL injury is pain directly over the ligament. Swelling over the torn ligament may appear, and bruising and generalized joint swelling are common 1 to 2 days after the injury. In more severe injuries, patients may complain that the knee feels unstable
Treatment
Treatment of an MCL tear depends on the severity of the injury. Treatment always begins with allowing the pain to subside, beginning work on mobility, followed by strengthening the knee to return to sports and activities. Bracing can often be useful for treatment of MCL injuries. Fortunately, most often surgery is not necessary for the treatment of an MCL tear.
Treatments For Unhappy Triad Injury
Treatment of the unhappy triad requires surgery. An ACL surgery is common and the meniscus can be treated during the surgery as well. The MCL is rehabilitated through time and immobilization. Physical therapy after the surgery and the use of a knee brace helps speed up the healing process.A typical surgery for a blown knee includes:
- Patellar tendon autograft (autograft comes from the patient)
- Hamstring tendon autograft
- Quadriceps tendon autograft
- Allograft (taken from a cadaver) patellar tendon, Achilles tendon, semitendinosus, gracilis, or posterior tibialis tendon
The goal of reconstruction surgery is to prevent instability and restore the function of the torn ligament, creating a stable knee. There are certain factors that the patient must consider when deciding for or against surgery.