C. Comstock et al., A CLINICAL AND RADIOGRAPHIC STUDY OF THE SAFE AREA USING THE DIRECT LATERAL APPROACH FOR TOTAL HIP-ARTHROPLASTY, The Journal of arthroplasty, 9(5), 1994, pp. 527-531
The purpose of this clinical and radiographic study is to determine wh
ether the surgeon can remain within the 5 cm ''safe zone'' while using
the direct lateral approach during total hip arthroplasty (THA) witho
ut endangering the superior gluteal nerve. The direct lateral approach
was used in a prospective, consecutive series of 36 primary THAs in 3
1 patients performed by one surgeon. At the time of closure of the abd
uctor muscle layer, a small metallic clip was placed at the superior e
xtent of the incision into the gluteus medius. After surgery, the pati
ents were mobilized on crutches with protected weight bearing for eith
er a 6-week (hybrid THA) or 12-week (uncemented THA) period. Before su
rgery, and at 3, 6, and 12 months after surgery, abductor strength and
the Trendelenburg sign were measured by the same physical therapist.
The vertical distance from the superior pole of the greater trochanter
to the base of the clip was measured on all radiographs of the pelvis
and corrected for magnification. Before surgery, only 25 of the 36 hi
ps demonstrated abduction strength of 4/5 or greater. Three months aft
er surgery, 34 hips had a grade of 4/5 or greater for abductor strengt
h. The Trendelenburg sign was positive in 24 of 34 hips before surgery
, in 5 hips at 3 months, in 1 hip at 6 months, but negative in all hip
s by 12 months. The clip was located 3.2 +/- 1.3 cm (mean +/- SD) vert
ically from the superior pole of the greater trochanter. In 34 of 36 h
ips (95%), the 5 cm safe zone was respected. There was no correlation
between abductor strength and the distance of the clip from the superi
or pole of the greater trochanter. It would appear that, with careful
surgical technique, the direct lateral approach can be safely performe
d without compromising the superior gluteal nerve.