Spondylolisthesis refers to the slipping of part or all of one vertebra forward on another.
It is often associated with defects in the bone (called the Pars) that usually develop in early childhood and have a definate family predisopsition.
Pars defects that develop due to athletic activity (stress fractures) are common in cricketers or athletes involved in hypertension activities.
Spondylolisthesis is most commonly seen in children between the ages of 9 and 14. In the vast majority of cases it is the L5 vertebra that slips forward on the S1.
The spondylolistheses is graded according to the degree of slip of the vertebra. A grade I slip denotes that a vertebra has slipped up to 25% over the body of the vertebra underlying it; in a grade II slip the displacement is greater than 25%; in a grade III slip, greater than 50%; and in a grade IV slip, greater than 75%. Lateral X-rays best demonstrate the extent of vertebral slippage.

Physiotherapy treatment of athletes with grade I or grade II symptomatic spondylolisthesis involves:

• Rest from aggravating activities combined with abdominal and extensor stabilising exercises and hamstring and hip flexor stretching.
• Gentle lumbar traction.
• Antilordotic bracing, which may also be helpful.
• Mobilisation of stiff joints above or below the slip on clinical assessment; gentle rotations may be helpful in reducing pain; manipulation should not be performed at the level of the slip.