The “approach” refers to the pathway that the surgeon takes through the soft tissues to reach the bone and perform hip replacement. The approaches are: anterior (Smith-Petersen), antero-lateral (Watson-Jones), lateral (Harding), and posterior (Kocher-Langenbeck). The names in parentheses refer to surgeons who described the approach. Wikipedia references these approaches and the soft tissue intervals they follow. This Wikipedia reference accurately reflects what is currently accepted medical terminology for orthopedic presentations and publications as well as patient information.
Surgical approaches ideally follow inter nervus (between nerves) and inter muscular soft tissue intervals to limit the chance of muscle and nerve damage. The important nerve damage to be avoided is to the motor nerves that provide the electrical signal for hip muscle action. These motor nerves are the superior gluteal nerve which enervates the gluteus medius, gluteus minimus, and tensor fascia lata muscles and the inferior gluteal nerve which enervates the gluteus maximus muscle.
The anterior (Smith-Petersen) approach is the only approach that is both inter nervus and inter muscular and follows the interval between the tensor fascia lata and sartorius muscles.
The antero-lateral (Watson-Jones) approach comes closest to also meeting these criteria however the hip deltoid (combination of tensor fascia lata and gluteus maximus muscles with the ilio tibial band) is split. Also, with this approach following the interval between the tensor and gluteus medius muscles it is not inter nervus and places the superior gluteal nerve branch to the tensor at risk.
The lateral (Harding) approach can impair fuction of the important abductor muscles by detachment of the gluteus minimus muscle and splitting the gluteus medius muscle. Gluteus medius splitting also endangers the superior gluteal nerve. Abductor muscle or superior gluteal nerve impairment can cause a limp,
The posterior (Kocher-Langenbeck) approach splits the gluteus maximus and detaches the external rotator muscles from the femur. The external rotator muscles (particularly the obturator externus muscle) are active in preventing hip dislocation and also during athletic activity requiring hip rotation (golf, tennis, skiing, martial arts).
Largely because of the above factors, I prefer the anterior (Smith-Petersen) approach.
Though the above definitions of approaches are more and more adhered to, there remains confusion and I would say misuse of the term “anterior approach”. Some surgeons may refer to the antero-lateral (Watson-Jones) approach as anterior. Some surgeons may even refer to the lateral (Harding) approach as anterior.
Proper definition is best to avoid this confusion.
A tip for the enquiring patient: anterior approach is almost always performed with the patient supine (on their back). If the surgeon operates with the patient lateral (on their side) but calls his approach anterior, his approach is actually likely to be not anterior but either antero-lateral or lateral.
Joel Matta, MD