Diagnosing a Musculoskeletal Groin Injury
The Hip Joint
When discussing a groin injury, the hip is a logical place to start. Your hip joint is the largest weight bearing joint in your body. It is designed to absorb shock, generate force, while maintaining an impressive range of motion when functioning correctly. Unfortunately this has also made the hip joint very susceptible to injury due to the amount of repetitive motion and force this joint is subject to.
Understanding Motion Patterns of the Hip
The successful resolution of a groin injury often involves a complex understanding of kinetic chain relationships, and a functional understanding of how motion of the hip is related to specific anatomical structures. When you observe a deviation from normal hip motion after a groin injury, it is often a direct indication of which anatomical structures are involved in creating and perpetuating a groin injury.
A mechanical groin injury that involves the hip will be a combination of four functional muscle groups:
· Agonists (Prime mover) – Muscles that contract to produce a specific movement. Example: The quadricep is a prime knee extensor.
· Antagonists – Muscles on the opposite side of the joint of the agonist. Example: Hamstrings are antagonists to the quadriceps.
· Synergist – Muscles that limit motion as the prime movers contract and also assist motion. Example: The Iliopsoas, and tensor fascia lata are synergists to the quadriceps.
· Stabilizers – Muscles that fix or stabilize the bones of the origin of the prime movers.
An understanding of these structures, combined with a whole body examination of kinetic chain relationships, provides a practitioner insight into all the structures that may be involved.
This next section gives you a basic overview of structures involved in hip actions. Optimal hip function is about maintaining a balance of these structures in order to achieve stability in the hip while performing all actions.
Notice that only certain sections of muscles are involved in some specific actions and that the same muscles help to perform multiple actions depending on hip joint position. Once a practitioner has an understanding of these structures, they can often obtain a considerable amount of information just by observing patient motion. If the patient is having a problem performing a specific action, and it’s just a mechanical problem, it is most likely due to a combination of the following structures:
Muscles involved in hip flexion:
- Psoas and Iliacus.
- Medial Quadricep (Rectus Femoris).
- Adductor longus, brevis and magnus (The superior portion of the adductor magnus is involved in hip flexion).
- TFL (Tensor fasciae latae)
- Gluteus medius (Anterior portion of the muscle).
Muscles involved in hip extension:
- Gluteus Maximus – This is a prime hip extensor. If it is weak, an increased load will be passed onto the hamstrings. In addition, if the psoas muscle is tight, the gluteus maximus muscles will be turned off.
- Gluteus medius (Posterior portion of the muscle).
- Hamstrings (Semimembranosus, semitendinosus, biceps femoris – long head).
- Adductor magnus (Inferior portion of the muscle).
Muscles involved in hip adduction:
- Adductor Magus, Longus and Brevis. – Adductor longus is the most common muscle injured in a groin strain.
- Obturator externus.
- Gluteus Maximus (The lower section of the muscle).
Muscles involved in hip abduction:
- Gluteus medius and minimus.
- Gluteus maximus (upper section of the muscle).
- TFL (Tensor Fascia latae).
- Piriformis muscle, gemellus superior, gemellus inferior, obturator internus (These muscles are involved in abduction when the hip is flexed)
Muscles involved in medial rotation of the hip (Internal rotation)
- Gluteus Medius (Anterior section of the muscle).
- Gluteus minimus.
- TFL (Tensor Fascia latae).
- Medial hamstrings (Semimembranosus and Semitendinosus).
- Adductor Magnus and longus.
Muscles involved in lateral rotation of the hip (external rotation)
- Gluteus Maximus and medius (posterior section of the medius).
- The deep six (Obturator externus, quadratus femoris, gemellus superior, gemellus inferior, obturator internus, piriformis) – In cases of sciatica it is often assumed that the entrapment involves the pirformis muscle, when, in reality, entrapment of the sciatic nerve can involve any of these muscles.
- Lateral hamstring (biceps femoris – long head).
- Popliteus (This muscle is behind the knee – and is primarily involved in lateral rotation of the hip when the leg is in a fixed position
In part three of Resolving Groin Injuries we will cover treatment.
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