Direct repair of a defect in the pars interarticularis was performed with the use of bone 
grafting and internal fixation with pedicle screw –rod- laminar hook system in order to 
achieve a higher prevealance of osseus union than that achieved with commonly used 
procedures. This study was conducted in Minia University Hospital from October 2017 to 
January 2019, the study included 15 patients (5 males, 10 females) with mean age 26 years 
old and follow up ranging between 7 to 18 month with averge 9 month. Most of cases (60%) 
had spondylolysis at level L4, (33%) at L5 level and only one patient had multiple level 
spondylolysis at L3,4,5. The type of spondylolysis were of stress type (isthmic) in 7 patients 
(46%), traumatic in 5 patients (33%) and degenerative in 3 patients (20%). there were 2 
patients (13%) with hamstring tightness that improved postoperatively. The disc status was 
evaluated preoperatively in all patients to follow the grades of Pffirman classification in our 
inclusion criteria and it was as follow; the commonest was grade 1 in 53% of patients , grade 
2 in 26% and grade 3 in 20% patients that all included in the first 3 grades of pffirman 
classification . 80% of patients showing grade 0 spondylolithesis and 20% with grade 1 
spondylolithesis according to meyerding classification that all are included in our inclusion 
criteria. Only 2 patients are associated with other injuries in polytrauma patients.