Groin Strain

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Original Editors - Els Van Haver

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Search Strategy

Keywords:
Groin tendinitis, adductor strain, adductor tendinitis, iliopsoas strain, iliopsoas tendinitis, abdominal strain, abdominal tendinitis, muscle strains, groin pain
Databases searched:
Pedro, google scholar, Pubmed, Web of Knowledge and Library of the VUB

Definition/Description

A groin strain is an injury to the muscle tendon unit that produces pain on palpation of the adductor tendons or its insertion on the pubic bone with or without pain during resisted adduction.(1)
Groin muscle strains are encountered more frequently in ice hockey and soccer than other sports.
These sports require a strong eccentric contraction of the adductor musculature during competition and practice. (2)
The underlying injury is most often a muscle or tendon strain at the insertion of the tendon of the adductor muscle to the bone. (3)

The difference between groin tendinopathy and strain are:
- First of all strains are acute and tendinosis are chronic. A tendinosis is a repetitive strain.
- The second difference is that acute injuries are more often localized in the myotendon junctions and chronic injuries are localized at the tendinous insertions on the pubic bone. Fig. 2 (3)

Muscle Strain

Muscle StrainAdductor Tendinitis

Clinically Relevant Anatomy

In human anatomy, the groin is the junctional area between the abdomen and the thigh on either side of the pubic bone. This is also known as the medial compartment of the thigh.
The groin muscles consist of three large groups of muscles that can be injured:
The abdominal-, iliopsoas- and adductors-group.
1. The adductors group:
The adductors of the hip joint include 6 muscles: the adductor longus, magnus, and brevis and the gracilis, obturator externus, and pectineus. All these are innervated by the obturator nerve, with the exception of the pectineus, which receives innervation from the femoral nerve. The primary function of this muscle group is adduction of the thigh in open chain motions and stabilization of the lower extremity and pelvis in closed chain motion. The adductor longus is most commonly injured during sporting activity. (4) The proximal attachment of the adductor longus contributes to an anatomical pathway across the anterior pubic symphysis that is likely required to withstand the transmission of large forces during multidirectional athletic activities. Its lack of mechanical advantage may make it more susceptible to strain.(21)

As shown in fig 1., the adductors all originate on the pubic ramus as almost all insert on the linea aspera of the posterior femur. The posterior head of the adductor magnus has a proximal attachement on the ischial tuberosity antero-inferoirly and attaches distally on the medial distal femur at the adductor tubercle. The gracilis insertion is on the medial border of the tuberosity of the tibia. (3)

Hip_Anatomy

2. The abdominal group:
The abdominal musculature comprise the rectus abdominis, the obliques internus and externus abdominis.

Abdominal_Muscle_Anatomy

3. The iliopsoas group:
The iliopsoas, comprised of iliacus and psoas major muscles, is the only muscle directly connecting the spine and the lower limb. (2)

Hip_Anatomy

Epidemiology /Etiology

Groin strains are common amongst athletes who compete in sports that involve repetitive twisting, turning, sprinting and kicking. (5) Strain injuries to the groin are among the most common groin injuries in adult male soccer players. Groin strain accounts for 11% to 16% of all soccer injuries. (6) Groin strains are also known from other sports such as ice hockey, running, tennis, rugby, American football, basketball and others. (7)
The exact incidence of groin muscle strains in most sports is unknown because athletes often play through minor groin pain and the injury goes unreported. In addition, overlapping diagnoses can skew the incidence. (4)

Musculotendinous injuries to the groin are mainly a consequence of cumulative microtraumas (overuse trauma, repeated minor injuries) leading to chronic groin pain. Cumulative or single injury seem to be important etiological factors. Although in some cases groin pain is due to an acute injury, typically a direct injury to the soft tissues resulting in muscle haematoma, the underlying injury is most often a muscle or tendon strain at the tendinous insertion of the adductor muscles to the bone. A chronic tendinitis of the adductor muscles/tendons, especially that of the adductor longus, is the most frequently diagnosed (9)

Injury mechanism can be divided in 3 groups:
1. Direct blunt trauma
2. Forceful contraction
3. Microtrauma by repetitive injury
And subsequently result in muscle contusions, avulsions, tears and strains. (8)

Most common groin injury in athletes are muscle and tendon strain of the adductor muscle group. A common mechanism of this injury is when the adductors attempt to decelerate an extending, abducting leg by using an eccentric contraction to adduct and flex the hip. With the forceful eccentric contraction, the adductors may not be strong enough to withstand the force, and injury can occur. The injury may also occur during a forceful concentric contraction of the muscle.

Lower-extremity athletes such as ice hockey and soccer players are naturally more prone to this pathology due to the importance of the hip adductors in lower-extremity performance(11), who are sports that involve repetitive twisting, turning, sprinting and kicking. (5)

Characteristics/Clinical Presentation

The main sign of the adductor muscle injury is intense pain in the groin area.

Adductor_Tendinitis

The muscles that cross multiple joints or have a complex structure are more sensitive to strain injury. Strain injuries often arise from excessive stretching or stretching when the muscle is being activated. When there is a strain in the muscle, the damage is often localized near the muscle tendon junction. The muscle is getting weaker and the risk for further injury rises. (13)

Muscle_Strain

Clinically for an adductor strain, the patient presents with pain in the inner thigh and tenderness along the muscle belly, tendon or insertion. The pain is exacerbated by adduction. There is no loss of strength or range of movement. (10)

Tears frequently occur at the myotendinous junction, which is the weakest part of the muscle tendon unit, but is also commonly seen in the muscle belly. The same mechanism of injury that results in a muscle tear in an adult may cause an apophyseal avulsion in an adolescent. There is a well-established clinical grading system for muscle tears, which has 3 components:
- Grade 1: no loss of function or strength
- Grade 2: severe, with some weakness
- Grade 3: complete muscle tear and complete functional loss (8)

Grade 1 muscle tears can show normal appearances or a small area of focal disruption (<5% of the muscle volume), with hematoma and perifascial fluid relatively common on imaging with US and MRI.
Grade 2 injury corresponds to a partial tear, with muscle fiber disruption seen (>5% of the muscle volume) but not affecting the whole muscle belly.
Grade 3 injuries are complete muscle tears with frayed margins and bunching and/or retraction of the torn muscle fibers. (8)

• In acute grade I or II strains of the adductor muscle, there is a very intense pain in the groin area, like a sudden stab with a knife, if the athlete attempts to continue the activity. Locally a hemorrhage and swelling can be seen a few days after the injury. A typical trauma history, localized tenderness and difficulties to contract the hip abductors.
• Complete muscle tears or grade III strains are most often found in the distal musculotendinous junction located toward the insertion on the femur.
• In chronic cases, the symptoms of groin injury are often complex and uncharacteristic. With time, as the injury becomes more chronic, there is a tendency for the pain to radiate out distally along the medial aspect of the thigh or proximally toward the rectus abdominis. In chronic and subchronic cases, the symptoms are often vague and diffuse in location. The most common symptoms are pain during exercise, stiffness after exercise and in the morning, as well as pain at rest.

Stress fractures of femoral neck or the inferior ramus of the pubic bone can be revealed by bone scintigraphy or repeated radiographic examinations. (9)

Differential Diagnosis

The literature provides no consensus on diagnostic criteria for the various causes of groin pain among athletes. (7) There is also no consensus on definitions for groin injuries and the diagnosis is often difficult because of the wide variety of different diseases that can cause pain to the groin area. (6) The insertions of the rectus abdominis and adductor longus muscles are also very close to each other, which may result in difficulties in the differential diagnosis between tendinitis or partial rupture of these muscles. (9)

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