By: Clinique Orthopédique Duval

Hip replacement surgery, also known as total hip arthroplasty (THA) requires an artificial device to be placed in the damaged hip socket. In the past, a small diameter femoral head, which is the ‘ball’ in the ‘socket’ of the hip joint, was used to replace damaged hips. There were some disadvantages to them such as dislocation and subsequent repeat surgery.

In an effort to make a better hip joint, doctors have started to utilize large diameter femoral heads (LDHs) greater than 36 millimeters (mm).

After years of research and experience, the four Duval Clinic surgeons utilize large diameter head hip replacement for all their patients because it offers unrestricted hip range of motion after surgery and lower risk of dislocations compared to smaller bearing.

Advantages of a large diameter head
As their use and research increases, LDHs appear to provide a larger range of motion (ROM), which makes them more forgiving with regard to how and where they are placed. Large diameter hip replacements are particularly good for people who work in physically demanding fields or pursue an active lifestyle. Larger diameter head hip replacement had significantly low dislocation rates, approximately 1 per 1000 versus 1-3 per 100 with standard, smaller head size. The reduced dislocation rate seen in large diameter head THAs is a result of many possible factors such as suction effects of larger heads that fill a greater volume of the joint and reduce micro separation that can lead to loosening, and premature wear and tear. LDHs also increase the range of motion of the hip without causing the new joint to become pinched.

Because of its intrinsic stability and low dislocation risk, surgeons performing LDH THAs can tailor the procedure to the patient’s individual anatomy. The surgeon can adjust your leg length more precisely and minimize the risk of leg length discrepancy seen with smaller head sizes.  In the gait lab, it has been demonstrated that a large diameter head THA restores the center of gravity and gait pattern to normal. By using a posterior approach with LDH THAs, our surgeons do not impose postoperative range of motion restrictions. It simplifies postoperative management, especially in patients undergoing bilateral procedures. There is less need for patient education and confidence in the hip’s performance is much higher. Patients often experience a much supplier hip, especially when preoperative contractures are present, with increased likelihood of having a forgotten hip.

Large diameter head hip replacement is available in two main bearings: ceramic-on-ceramic or dual mobility.

Ceramic-on-Ceramic THA
Ceramic bearing has existed for more than 50 years. These surfaces have a very high resistance to wear, making them the ideal option for younger (usually less than 65 years old) and very active patients. Dr. Vendittoli and Dr. Duval recently reported a success rate of 97.2% after more than 21 years with smaller head ceramic total hip arthroplasty bearings. (Read more here).  In 2011, Dr. Lavigne and Dr. Vendittoli, were the first surgeons in North America implanting large diameter THA. Using a larger diameter reduces component impingement risk, increasing stability. Since then, the Duval Clinic surgeons have implanted more than 3000 ceramic large diameter THAs. The clinical results after 5 years are excellent, with a 99% implant survival rate. (Read more here). Although these hard bearings may produce occasional noise/squeaking, it does not appear to be bothersome to the patients. With such prosthesis, most patients can resume heavy labor and demanding sport activities without being concerned by implant wear.

Dual mobility THA
Another hip replacement design using a large diameter head is the dual mobility hip. Dual mobility takes the double principle of a small articulation to minimize the problems of wear, coupled with a polyethylene “big articulation” to stabilize the hip and prevent instability. Large diameter hip with a dual-mobility femoral head is very attractive because it has a lower cost, and it does not produce noise. Patients older than 65 years can expect a dual mobility THA to last for the rest of their life. Using these protheses for more than 10 years, the Duval Clinic surgeons want to provide their older patients a simpler post-operative rehabilitation without range of motion restriction and ultimately, a forgotten joint.

Conclusion
The supra-physiologic arc of motion provided by the large diameter head THA makes it a forgiving procedure. It also permits a better reproduction of individual patient anatomy (leg length). Once the soft tissues are healed, it allows unrestricted range of motion, for activities and work occupations. For these reasons, it may increase the likelihood of having a forgotten hip. Many years ago, the surgeons working at the Duval Clinic adopted the “LDH THA for all” principle to maximise their patient joint stability and quality of life.