Does the Lumbar Spine Need to be Supported to
Stabilize the Pelvis During Total Hip Arthroplasty in
the Lateral Position?
D. Prakash, FRCS (Orth),* R. King, FRCS,* and C. Hayes, BSc†
Abstract: Total hip arthroplasty is done commonly with the patient in the lateral
position. It has been postulated that the lumbar spine may sag in this position
because it forms a mobile link between the rigidly held thoracic spine and the sacrum
and may cause the pelvis to tilt in the coronal plane, leading to malpositioning of the
acetabular cup. To conﬁrm this hypothesis, 10 consecutive patients seen in the
preoperative assessment clinic had 2 anteroposterior radiographs taken in the lateral
position. The area of exposure was from the lower thoracic spine to the sacrum. In
the ﬁrst radiograph, the lumbar spine was unsupported, and in the second, it was
supported. The radiographs showed that the support did not make any signiﬁcant
difference to the position of the lumbar spine or to the position of the pelvis. Key
words: arthroplasty, lumbar spine, acetabular cup, pelvic stability.
Total hip arthroplasties (THAs) commonly are per-
formed with the patient in the lateral position. Rigid
support of the pelvis is imperative to achieve correct
orientation of the acetabular cup [1,2]. The usual
method of stabilizing the pelvis in this position is to
have anterior and posterior supports only. Because
the lumbar spine is mobile, it was postulated that it
might sag under its own weight, causing the pelvis
to tilt in the coronal plane. If this were to occur
undetected by the operating surgeon, it would lead
to malpositioning of the acetabular cup intraopera-
tively. This study was undertaken to determine the
validity of this postulate.
Patients and Methods
We reviewed 10 consecutive patients who at-
tended the preoperative assessment clinic before
their primary THAs. It was ensured that none of the
patients had scoliosis, a paralytic disorder, or a
Two anteroposterior radiographs were taken of
each patient in the lateral position. The radiographs
exposed the spine from the lower thoracic region to
the sacrum. In the ﬁrst radiograph, no support was
provided to the lumbar spine. Before the second
radiograph was taken, a well-padded, custom-made
instrument with adjustable height was placed be-
tween the lower ribs and the iliac crest and raised to
support the lumbar spine. This lumbar support
worked on a similar principle to a car jack, with the
elevation being caused by the rotation of a central
rod, which is threaded in opposite directions at its
ends. A removable handle was used to adjust the
height of this instrument when it had been put in
place under the patient (Figs. 1 and 2). The second
From the *Queen’s Medical Centre, Nottingham; and †Derbyshire
Royal Inﬁrmary, Derby, United Kingdom.
Submitted August 14, 2001; accepted September 6, 2001.
No beneﬁts or funds were received in support of the study.
Reprint requests: D. Prakash, FRCS (Orth), 41 Westkirke
Avenue, Grimsby, DN33 2HS UK. E-mail: Divya711@ hotmail.com.
Copyright 2002, Elsevier Science (USA). All rights reserved.
The Journal of Arthroplasty Vol. 17 No. 3 2002