Posterior Lateral Approach
The posterior lateral operation technique has been pioneered at the Arthritis Institute. Our gait studies show this approach to be superior to both long incisions and anterior incisions. Instrumentation to allow the performance of this operation with ease for the surgeon and accuracy of technique has been developed by Dr. Dorr. The posterior lateral incision is used by Drs. Dorr and Long. The advantages of the posterior incision are that there is, as shown to date with gait studies, better performance with posterior incisional operations than with anterior. The main reason for this is that there is less damage to the gluteus medius muscle with posterior incision that with anterior incision. Even with anterior incisions that do not cut any muscle, the gluteus medius muscle has so much retraction against it, that its function may be compromised for a period of time postoperatively. Since the gluteus medius muscle is the most important stabilizer for the hip, the avoidance of injury to it during hip surgery has value. The anterior incision also has more injury to the gluteus minimus muscle. The anterior capsule is always opened with the anterior incision, and 25% of gluteus minimus muscles insert into the anterior capsule. Of course, the capsule is repaired at the completion of that operation, but still, there is some injury to that muscle.
With posterior incision, there are only 3 cuts to hip tissue. The first cut is a division of the gluteus maximus muscle, which is of lesser importance to the hip. Because EMG studies at 6 weeks post surgery show this muscle functioning normally. The second hip tissue cut are the small external rotator muscles, but these muscles have little consequence to the functional recovery of hip replacement. Therefore, this particular muscle injury is also of little consequence as long as the implant parts are mated correctly so that the intrinsic stability of the hip replacement is good. The function of the small external rotators over time is to provide posterior stability for the hip replacement. This does occurs over time after hip replacement because the posterior capsular incision and external rotator muscles are repaired.
The posterior lateral, as performed at the Arthritis Institute, has a strong track record. We have shown over three years that this incision reduces the pain for the patient and increases function earlier. 80% of our patients go home on a crutch or a cane. With the traditional incisions, our average discharge time was 5 days postoperative. With the small incision, the discharge time for patients who desire to do so, and all patients under 65 years, is no more than 48 hours. With the traditional incisions, the pain control during hospitalization was intravenous narcotics. With the small incisions, we use only pain pills in the hospital, and on the third postoperative day, the average number of narcotic pain pills taken by patients is 1.1. With the traditional incision, the majority of patients went home with two crutches, or for the more elderly, a walker. With the small incision, 80% of patients go home on a cane. Finally, with the posterior mini-incision, we have demonstrated through gait studies that we have a return of 80% of the normal function by 6 to 10 weeks postoperatively, and that the posterior incision is the best mini-incision. The data for our patients with posterior lateral has been summarized in an article published in the Journal of Bone and Joint Surgery(November 2003). 2 This article summarizes the outcomes for the patients, the pain management and anesthesia changes that we have made to allow the patient to function better and earlier in the hospital, and to feel better in the postoperative period after total hip replacement. Clearly, one of the main advantages of the small incision surgery has been not only the decrease in pain and increase in function for the patient, but the improvement in the overall process of the operation for all patients.