The role of lesser trochanter fragment in unstable pertrochanteric A2 proximal femur fractures - is refixation of the lesser trochanter worth the effort?

BACKGROUND

Instability of osteoporotic pertrochanteric fractures is defined by loss of medial/lateral cortical integrity with the posteromedial fragment including the lesser trochanter being pivotal for load distribution. Literature addressing the importance of lesser trochanter refixation is scarce. To clarify the effect of lesser trochanter refixation on primary stability in these fractures, following study was performed.

METHODS

21 femora were match-paired in 3 groups and osteotomized, creating pertrochanteric fractures (AO-31A2). Group 1 was stabilized with a proximal femoral nail, group 2 with a dynamic hip screw and group 3 with an augmented proximal femoral nail. Each femur was tested non-destructively at 200 and 400N with and without refixation of the lesser trochanter (configuration A/B). The overall stiffness and movement of the femoral neck was recorded.

FINDINGS

At 200N, refixation reduced movement of the femoral neck and increased overall stiffness significantly in group 1 and 3. At 400N, refixation decreased movement of the femoral neck not significantly in all groups (1=38%, 2=36%, 3=43%). The augmented proximal femoral nail after refixation showed the highest stability of all constructs.

INTERPRETATION

Refixation of the lesser trochanter may increase the primary stability of pertrochanteric fracture osteosynthesis as all groups showed a higher primary stability. Therefore, refixation should be considered in unstable, osteoporotic fractures. If additional trauma through refixation appears inappropriate, cement augmentation should be performed as it showed only 9% less stability than a non-augmented proximal femoral nail with refixation of the lesser trochanter.