Surgical Approaches for Hip Resurfacing-Explaining the anterior approach and the posterior approach
Peter Brooks MD Cleveland ClinicMost 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.