Background: Abduction weakness and limping is a well-recognized
complication of closed antegrade insertion of femoral nails. Iatrogenic
injuries to the superior gluteal nerve and the gluteus medius muscle are the
most likely contributing factors. The purpose of this study of cadavers was to
assess the risk of nerve and muscle injury with various lower-limb positions
used during nail insertion.
Methods: We studied thirteen hips of ten formalin-fixed adult
cadavers. With the cadaver in the full lateral position, a 9-mm reamer was
introduced in a retrograde fashion from the intercondylar notch and passed
through the gluteus medius muscle. The distance between the point of entry of
the reamer into the undersurface of this muscle and the inferior main branch
of the superior gluteal nerve (the nerve-reamer distance) and the distance
between the entry and exit points of the reamer in the gluteus medius muscle
(the intramuscle distance) were measured in three different hip positions:
15° of flexion and 15° of adduction (Position 1), 30° of flexion
and 30° of adduction (Position 2), and 60° of flexion and 30° of
adduction (Position 3).
Results: In Position 1, the average nerve-reamer distance was 7 mm
and the average intramuscle distance was 24 mm. In three hips the reamer
injured the nerve directly, and in two other hips the distance was =5 mm.
In Position 2, the average nerve-reamer distance was 21 mm and the average
intramuscle distance was 18 mm. In Position 3, the average nerve-reamer
distance was 33 mm and the average intramuscle distance was 11 mm. None of the
reamers in this position came closer than 20 mm to the nerve.
Conclusions: The risk of injury to the superior gluteal nerve and
the gluteus medius muscle during closed antegrade insertion of a femoral nail
is lessened by increasing the amount of hip flexion and adduction.
Clinical Relevance: The risk of injury to both the superior gluteal
nerve and the gluteus medius muscle is higher with limited degrees of hip
flexion and adduction, such as are possible in the supine position on a
fracture table, than it is with greater degrees of hip flexion and adduction,
which are possible in the lateral position on a fracture table or in the
so-called sloppy lateral position on an ordinary table. Therefore, insertion
of a femoral nail with the hip in increased flexion and adduction might help
to lower the risk of injuries to the superior gluteal nerve and the gluteus