Aim:

In recent times, instrumentation with pedicle screw is a widely used method in vertebral surgery. In this study, we aimed to evaluate rate of the most common complication of this method, namely, pedicle screw malposition and its clinical implications in patients diagnosed as Lenke Type 1 idiopathic scoliosis and thus having undergone posterior intervention and instrumentation.

Patients and Method:

Forty-nine patients have undergone posterior intervention and instrumentation because of Lenke Type 1 adolescent idiopathic scoliosis between 2005 and 2011 and 42 of them with continuous screw placement was included into the study (6 males; 36 females; mean age 13.8 years). Position of screws placed into thoracic and lumber pedicles was evaluated by anteroposterior and lateral post-op radiographies by three orthopaedists.

Results:

A total of 944 pedicle screws were found to be placed into thoracic and lumbar pedicles. Mean number of placed screws per patient was calculated as 22.5. Most of the screws were placed at T3-T4-T5-T6-T7-T8-T9-T10-T11-T12 (n:84) vertebra segments and L2 (n:2) segment was the level where the lowest number of screws were placed. Rate of screws in normal position within the pedicles was 86.4% (n=816) and the rate of screws out of the pedicles was 13,6% (n=128). 74(57.8%) of the screw malposition were at lateral of the pedicle and 35 (27.3%) were at the inferior of the pedicles, 13 (10.2%) were at the superior of pedicle or at upper disc distance, 6 (4.7%) were at medial of the pedicle and 63% of these screws were at concave side and 37% were at convex side. Screw malposition was most commonly observed at T11 level. There was no screw malposition at L1-L2 levels. No complication with early symptoms was observed in any of the patients.

Conclusion:

In this study; although rate of screw malposition was 13,6%, absence of any complication such as neurological deficit, pseudo-arthrosis, infection and pulmonary emboli at early stage has revealed that instrumentation by placing pedicle screws free hand in surgical treatment of adolescent idiopathic scoliosis is a safe and appropriate surgical method.

Keywords: Adolescent idiopathic scoliosis, Lenke type 1 curve, posterior selective fusion, screw malposition