Surgical Approaches for Hip Resurfacing-Explaining the anterior approach and the posterior approach

Peter Brooks MD
Cleveland Clinic

Most hip replacement and resurfacing surgery in the USA, about
80%, is performed through a posterior approach. About 20% of US
hip surgeons prefer some variation of an anterior approach (antero-lateral,
direct lateral, trans-gluteal, or true anterior). Anterior
approaches are also more common in Europe and Canada.

In the posterior approach, the incision, dissection, and
dislocation of the hip joint are all performed posteriorly
(toward the buttock). The large gluteus maximus is split, and
the gluteus medius and minimus muscles (hip abductors) are
retracted, but not cut. A number of smaller muscles, the “short
external rotators” including piriformis, obturator internus,
gemelli, quadratus, and obturator externus, are cut, and the
tendon of gluteus maximus may also be partially divided. With
these out of the way, the posterior hip capsule is incised, and
the hip is dislocated posteriorly by turning the foot toward the
ceiling. The acetabulum and femoral head are then resurfaced,
the muscles and capsule are repaired, and the incision closed.

In the direct lateral approach, (or trans-gluteal approach as it
is also known), the incision is on the side of the hip, and from
there the dissection proceeds towards the front of the hip
joint. The hip abductors (gluteus medius and minimus) are split
in the line of their fibers, peeled off the greater trochanter
of the upper femur in continuity with upper fibers of the vastus
lateralis, and retracted anteriorly, allowing the anterior
capsule to be cut, and the hip to be dislocated anteriorly, with
the foot pointing down to the floor. During closure, these
muscles all tend to lie back where they belong, and since they
have not been cut across their fibers, there is no tendency for
their repair to pull apart. The antero-lateral approach is
similar, but retracts or detaches, rather than splits, the
abductors.

The true anterior approach can be adapted to hip resurfacing,
actually better than for hip replacement, since exposure to the
shaft of the femur is difficult (and not needed in resurfacing).
It is not popular among surgeons who operate on adults, but is
fairly common in pediatric orthopedics.

Different approaches have different issues. The posterior
approach is very well known in the USA, and BHR developers Mr
McMinn and Mr Treacy use it routinely as well. Theoretically it
should have a higher dislocation rate, due to the fact that
dislocation almost always occurs posteriorly, and this approach
disrupts all the potential restraints to posterior dislocation.
But dislocation after hip resurfacing is much less of a problem
than it is with hip replacement, due to the very large head
size. The blood supply to the femoral head stands a greater
chance of damage through the posterior approach, since that is
where the vessels mostly are. The important hip abductors
(gluteus medius and minimus) are left completely intact.

The direct lateral (trans-gluteal) approach has the advantage of
a lower dislocation rate, and less likelihood of damage to the
blood supply of the femoral head. In addition, no muscles are
actually cut across; they are just split, or teased apart in the
line of their fibers, which should lead to more reliable
healing. The exposure of the socket is a “straight shot”, since
the acetabulum is an anteriorly facing structure. The
disadvantages are that there is nonetheless surgical trauma to
the abductors which, if substantial, could cause a limp. There
are also reports of heterotopic ossification, although this may
occur with any approach.

The true anterior approach can be associated with injury to a
sensory nerve responsible for the side of the thigh (lateral
femoral cutaneous nerve), and the location of the incision in
the groin is not the cleanest part of the body. It is also by
far the least commonly used of these incisions for adult hip
surgery, so at least for the time being, we do not have a lot of
data.

The main thing to keep in mind is that any of these surgical
approaches can work just fine. All have been modified in many
ways as surgeons find better ways to do things. The most
important thing for a patient to decide is who will do their
surgery, not how it will be done. The surgeon, drawing on his or
her own training, experience and beliefs, will decide what works
best in their hands.