ABSTRACT
STUDY DESIGN: This is a retrospective study. OBJECTIVES: We wanted to assess the stability of distal instrumentation using the bilateral S1 and sacral alar screws for the treatment of degenerative lumbar deformity. SUMMARY OF LITERATURE REVIEW: Various instrumentation methods have been introduced for increasing the strength of lumbosacral fusion. However, there are not many clinical studies that have evaluated the effectiveness of a sub-S1 alar screw for treating degenerative lumbar deformity surgery. MATERIALS AND METHODS: A total of 39 patients with degenerative lumbar deformity were treated by long fusion and we retrospectively analyzed these patients after a minimum follow-up of 1 year. All the patients underwent an operation with distal instrumentation using either bilateral S1 screws alone (the S1 group) or additional bilateral sub-S1 sacral alar screws (the SA group). There were 19 patients in the S1 group and 20 patients in the SA group. The stability of the distal instrumentation was assessed by breakage or backout of a rod and/or screws based on simple radiography. RESULTS: Instability of the distal instrumentation was detected in 6 cases (32%) in the S1 group and in 1 case (5%) in the SA group. The SA group had a more stability of the distal instrumentation than that of the S1 group with a significant difference (P0.05). CONCLUSIONS: Bilateral sacral alar screws coupled with bilateral S1 screws can provide good distal fixation for stability of the distal instrumentation when performing long fusion for treating degenerative lumbar deformity.
Subject(s)
Humans , Congenital Abnormalities , Follow-Up Studies , Retrospective Studies , SuccinatesABSTRACT
PURPOSE: We wanted to analyze the influences of risk factors on avascular necrosis and nonunion after multiple pinning for a femoral neck fracture. MATERIALS AND METHODS: Among the cases of multiple pinning for a femoral neck fracture that were seen at our department from June 1995 to May 2006, we analyze 102 cases that had more than 2 years of follow-up. We evaluated the influence of such factors as the age, gender, injury on the right- or left-side, the degree of displacement, the time to operation, the angle of fracture, the accuracy of reduction and posterior cortex comminution on avascular necrosis and nonunion after multiple pinning for a femoral neck fracture. RESULTS: The incidences of AVN and nonunion were 13.7% (14/102) and 10.7% (11/102), respectively. The degree of displacement was a significant factor that influenced the development of nonunion (p<0.05). The time to operation and the angle of fracture were significant factors that influenced nonunion (p<0.05 & p<0.05) and avascular necrosis (p<0.05 & p<0.05). The posterior cortex comminution was a significant factor that influenced nonunion (p<0.05) and avascular necrosis (p<0.05). CONCLUSION: The important risk factor for avascular necrosis was the angle of fracture over 60 degrees. The important risk factors for nonunion were the time to operation (over 24 hours), posterior cortex comminution and an angle of fracture over 60 degrees.