The modified Smith–Petersen and Kocher–Langenbeck
approaches were used to expose the lateral cutaneous nerve of the
thigh and the femoral, obturator and sciatic nerves in order to
study the risk of injury to these structures during the dissection,
osteotomy, and acetabular reorientation stages of a Bernese peri-acetabular
osteotomy. Injury of the lateral cutaneous nerve of thigh was less likely
to occur if an osteotomy of the anterior superior iliac spine had
been carried out before exposing the hip. The obturator nerve was likely to be injured during unprotected
osteotomy of the pubis if the far cortex was penetrated by >
5 mm.
This could be avoided by inclining the osteotome 45° medially and
performing the osteotomy at least 2 cm medial to the iliopectineal
eminence. The sciatic nerve could be injured during the first and last
stages of the osteotomy if the osteotome perforated the lateral
cortex of ischium and the ilio-ischial junction by >
10 mm. The femoral nerve could be stretched or entrapped during osteotomy
of the pubis if there was significant rotational or linear displacement
of the acetabulum. Anterior or medial displacement of <
2 cm
and lateral tilt (retroversion) of <
30° were safe margins. The
combination of retroversion and anterior displacement could increase tension
on the nerve. Strict observation of anatomical details, proper handling of
the osteotomes and careful manipulation of the acetabular fragment
reduce the neurological complications of Bernese peri-acetabular
osteotomy. Cite this article:
Recently, femoroacetabular impingement has been recognised as a cause of early osteoarthritis. There are two mechanisms of impingement: 1) cam impingement caused by a non-spherical head and 2) pincer impingement caused by excessive acetabular cover. We hypothesised that both mechanisms result in different patterns of articular damage. Of 302 analysed hips only 26 had an isolated cam and 16 an isolated pincer impingement. Cam impingement caused damage to the anterosuperior acetabular cartilage with separation between the labrum and cartilage. During flexion, the cartilage was sheared off the bone by the non-spherical femoral head while the labrum remained untouched. In pincer impingement, the cartilage damage was located circumferentially and included only a narrow strip. During movement the labrum is crushed between the acetabular rim and the femoral neck causing degeneration and ossification. Both cam and pincer impingement lead to osteoarthritis of the hip. Labral damage indicates ongoing impingement and rarely occurs alone.
