Hip and knee replacement surgeries are among the most common operations performed in the U.S. The number of hip replacements performed in the U.S. has increased substantially with an estimated 400,000 Medicare patients opting for total hip or knee replacements in 2015. While much of this can be attributed to an aging population, statistics show dramatic increases in joint replacement among the middle-aged who want to maintain an active lifestyle.
Hip replacement surgery is a common procedure for patients who suffer from debilitating arthritis of the hip. Patients typically exhaust non-invasive treatment options including therapy for muscle strengthening, weight loss, and taking anti-inflammatory medications before choosing surgery. However, at some point the pain and disability will become great enough that the patient will require hip replacement surgery to alleviate the pain and disability. This typically correlates with an X-ray demonstrating "bone on bone" arthritis where the majority of the cartilage has worn away.
The majority of joint replacement patients experience excellent outcomes in terms of pain relief and returning to near normal function. Most patients can return to pain-free walking, hiking, playing golf, doubles tennis, and gardening to name a few activities. Although some patients can run after surgery, the implants are not designed for long distance or routine running.
In order to obtain access to the hip joint during surgery to implant the hip prosthesis, a surgeon may choose a variety of approaches to the hip. The traditional posterior approach is performed with the patient lying on their side and an incision is made on the posterior-lateral side of the hip.
Dr. David DeBoer
In this approach, the gluteus maximus muscle is divided and one or two of the short external hip rotator muscles must be cut (and subsequently repaired) to gain access to the hip joint. The posterior approach has been a tried and true method of performing hip replacement surgery with thousands of extremely happy patients.
With the continued pressure for less invasive surgery with a faster recovery, there has been a renewed interest in the anterior approach to the hip. The anterior approach, sometimes called the "direct anterior approach," is usually performed with the patient lying on their back with the help of a specialized operating table called the Hana fracture table. This table allows the operating staff to assist the surgeon by manipulating the leg to improve exposure of the hip joint.
The incision is on the anterior lateral side of the hip. As opposed to the more traditional posterior approach to hip replacement surgery, the anterior approach does not require cutting any tendons during the procedure. A c-arm fluoroscope is used throughout the procedure to aid with positioning and placement of the hip socket as well as the sizing and positioning of the femoral stem. Together these two bony structures form the hip joint and correct placement is important for correctly adjusting a patient's leg lengths if one leg is shorter than the other due to the loss of cartilage.
The anterior approach does cross a major cutaneous nerve and generally results in numbness along the outside of the thigh for several weeks. Occasionally, this numbness can be permanent.
There is much debate which approach is superior. There are pros and cons for both and the long-term outcomes are independent of the approach to the hip but rather the correct placement of the components and the type of the implanted bearing surfaces. There have been a few studies that report the short-term mobility in patients with the anterior approach may be somewhat better at 6 weeks post operatively. However, there were no significant differences between the two approaches by 3 months after surgery.
The other attractive reason some physicians and patients prefer the anterior approach is the absence of hip dislocation precautions immediately after surgery. In the posterior approach, the surgeon divides the hip capsule and transects two of the short hip rotator tendons. These are all repaired and require approximately 3 to 4 months to fully heal. During that time period, it is important for the patient to avoid the combination movement of deep hip flexion and internal rotation to avoid breaking the suture used to repair these structures and subsequent dislocation of the hip. Getting out of a deep chair or sofa, or getting up from a low toilet seat are possible situations where the hip may get into a position at risk for dislocation.
The anterior approach is much more difficult in patients with certain types of hip anatomy resulting in a larger dissection and soft tissue releases expose the hip joint. Wound healing may also be compromised in obese patients with the anterior hip approach due to the position of the incision contacting the belly. Lastly, many patients do not like the numbness on the side of their thigh even though it is usually transient.
In summary, the results of hip replacement surgery are very good for reducing hip pain and returning to near normal function regardless of the surgical approach to the hip. Surgeons become comfortable with different approaches to the hip so ask your surgeon his or her preference and the reasons for this preference. Most importantly, find a surgeon that you feel comfortable entrusting your hip replacement surgery to and with whom you can easily communicate.