The Pelvic Cross Syndrome
The Pelvic Cross Syndrome (also known as lower cross syndrome) is defined as an abnormal adapted posture of the lower back, which results from muscle strength imbalances. This is frequently associated with the combination of prolonged sitting and poor posture.
Signs & Symptoms
In this condition, the following may be perceived:
Increased curve (lordosis) of the lower back
Forward tilt of the pelvis
Tight hip flexor muscles (Iliopsoas)
Weak abdominals and bottom muscles (Gluteals)
Tight hamstrings (posterior thigh muscle)
Structures Involved in PCS
The Pelvic Cross Syndrome (PCS) commonly involves the Hip flexors (muscle responsible for bending the hip up), Gluteals (bottom muscles used to bring the hip back, and leg out to the side), abdominals (abdomen muscle) and the Hamstrings (muscle responsible for bringing the hip backwards).
To fully comprehend the reason as to why there is a muscle imbalance, we need to understand the concept that when a muscle is in a shortened or tightened state (ie. such as in Prolonged sitting and poor postures) for long periods of time, it causes the weakening of muscles on the opposite side of the body. This is referred as the “automatic reflex inhibition” by the brain.
The Mechanism of Muscle Imbalance
In PCS, the hip flexors become tight (due to poor posture). As a result of the automatic reflex inhibition by the brain, the abdominals and gluteals on the opposite side of the body weaken. Consequently, this muscle strength imbalance leads to an exaggerated curve in the lower spine which in turn causes low back pain. Because the gluteals are weak, its function is compromised and other muscles such as the hamstrings and back muscles are recruited to assist them in performing daily activities such as walking. This leads to overuse and tightness of the hamstrings and back muscles, which ultimately weaken the abdominals, and further increases the curve of the lower spine.
If these muscle differences are left untreated, the joints and muscles around may undergo changes progressively. Strength, flexibility and range subsequently decrease, which contributes to degenerative changes and pain in the lower back
However, physiotherapy can help to prevent these secondary degenerative changes and treatment techniques are largely aimed to stretch the tight muscles and to strengthen those that have been weakened so as to enhance optimal muscle function and to improve postural alignment of the lower back.