Effect of lag-screw positions on modes of fixation failure in elderly patients with unstable intertrochanteric fractures of the femur.
OBJECTIVE
To investigate the effect of lag-screw positions in the femoral head on modes of fixation failure.


METHODS
591 patients aged 65 years or older underwent sliding compression screw fixation for type A(1) (n=249) and type A(2) (n=342) intertrochanteric fractures of the femur after low-energy injuries. There were 18 cases of fixation failure; in 13 (group 1) the lag screw was placed in the central-central area, and in 5 (group 2) in the inferior 1/3-central area. Clinical variables of the 2 groups were compared.


RESULTS
All 18 cases of fixation failure were actually type A(23) and misinterpreted as type A(22) fractures. In 13 cases, failure was attributable to cut-out of the lag screws at the superolateral edge of the femoral head. In 3 cases, failure was attributable to telescoping and more than 2 cm shortening of the femur. In one case, failure was due to penetration of the lag screw into the acetabulum. In another case, failure was due to plate loosening with breakage of cortical screws. In the 13 cases with cut-out of the lag screw (group 1), the lag screw was placed in the central-central area (p<0.001). In the remaining 5 cases with no cut-out (group 2), the lag screw was placed in the inferior 1/3-central area (p<0.01). Complications occurred significantly earlier in group 1 than in group 2 patients (2.6 vs. 4.6 months, p=0.02). The tip-apex distance was significantly shorter in group 1 than in group 2 patients (19 vs. 30 mm, p<0.001).


CONCLUSIONS
Misinterpretation of type A(23) fractures as type A(22) may lead to fixation failure. Operative treatment should not be delayed once complications occur. The positions of the lag screw may affect the mode of fixation failure.
Wu
Chi-Chuan
CC
Department of Orthopedics, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan. ccwu@mail.cgu.edu.tw
Tai
Ching-Lung
CL
D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D005270:Femur Head / Q000601:surgery; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008297:Male; D011474:Prosthesis Design; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D017211:Treatment Failure