● Null hypothesis (H0): Unilateral pedicle screw with contralateral interbody cage has better outcomes than unilateral pedicle screw fixation with ipsilateral cage.

● Alternative hypothesis (H1):

Unilateral pedicle screw with contralateral interbody cage gives the same outcomes as unilateral pedicle screw fixation with ipsilateral cage.

Lumber interbody fusion is one of the commonest neurosurgical procedures. A lot of studies showed the value of unilateral approach which resulted in less cost, time and radiation exposure when use interbody cage with ipsilateral pedicular screws fixation in comparison to bilateral approach when use interbody cage with bilateral pedicular screws fixation.

Fusion rate, cage migration, and biomechanical stress were the main draw backs of unilateral approach by lumber interbody fusion with ipsilateral cage and screws. Cage size and location seemingly the main reasons with advice to use large cage and cage insertion in oblique fashion to cross the midline. This study was designed to solve these issues.

Sample size:

The Study will include 40 patients divided into two groups, each group containing 20 patients.

Inclusion Criteria:

• Patient acceptance.
• Both sexes.
• Age (21-60) years old.
• Patients with monosegmental lumber degenerative spinal diseases including lumbar spondylosis, spondylolysis, spondylolisthesis grade one, or lumbar disc prolapse.

Exclusion Criteria:

• Patient refusal.
• Altered mental status.
• Patients with associated comorbidity interfere with surgery.
• Extremes of age.
• Multiple level lumbar degenerative disease
• Trauma
• Spinal tumour
• Active infection
• Previous lumbar operation