While the basic steps of hip replacement surgery are similar, many variables depend on the patient, the orthopedic surgeon, and the type of prostheses that are used. Below are some common surgical variables patients may encounter.
Minimally Invasive Hip Replacement Surgery
Minimally invasive hip replacement surgery is defined differently by different people:
- Some surgeons define it by the actual size of the skin incision, with an incision of 10 cm or smaller indicating a more minimally invasive procedure.1
- Others define a minimally invasive surgery as one that uses techniques and modified tools to avoid cutting some of the muscle and other soft tissue around the hip. These approaches to the hip are theoretically more “muscle sparing.” (Hip replacement using the direct anterior approach fits this definition.)
No matter how it is defined, minimally invasive surgery can be technically challenging and pose a unique set of risks. Patients are encouraged to ask about their orthopedic surgeons’ experience. Evidence suggests surgeons who have performed at least 35 to 100 surgeries using a specific surgical method have lower complication rates.2,3
Computer-assisted Hip Replacement Surgery
Some orthopedic surgeons use computers during surgery to help ensure optimal placement of the new hip prostheses. Research suggests1 this technology helps ensure:
- Less variability in the placement of hip prostheses
- Better restoration of leg-length and hip joint mechanics
Computer-assisted navigation equipment is costly, and not all hospitals and surgical centers offer it.
Types of Prostheses
The exact design and shape of a prosthetic ball-and-socket can vary. For example:
- The prosthetic ball can range in size, typically 32 mm to 36 mm in diameter.6
- The femoral stem that fits into the femur (thighbone) can be short or long. A shorter stem is about 14 cm long, while a conventional stem can be nearly twice that length.7
- While the femoral stem is typically made of metal, the femoral head (“ball”) is usually made of metal or ceramic.
Similar types of differences exist among hip socket prosthetics.
There is no definitive scientific evidence showing certain hip prostheses are better than others for all patients.1,8 The type of prostheses used will depend on the surgeon’s preference and possibly the patient’s age, anatomy, and lifestyle.
Patients may be offered custom prosthetics, tailored to their particular anatomy. Custom prosthetics do not offer notable advantages for most patients.1 They may be appropriate for patients who have rare anatomical differences or certain medical conditions, such as a fractured femur.
Cemented vs. Cementless Prostheses
Another difference among prostheses is how they are attached to the bone. Components may be attached with bone cement or they may be “cementless,” allowing existing bone to grow into them.
- Cemented prostheses provide more reliable results in people over age 751 or with known osteoporosis.
- Cementless prostheses are used in the majority of hip replacements in the US,9 and are particularly favored in younger patients who do not have significant osteoprosis.1,10
Keep in mind that each patient is unique, and whether an orthopedic surgeon uses cemented or uncemented prostheses (or a combination) will depend on the surgeon’s preference and the patient’s lifestyle and physiology.
The Surgeon’s Experience
One of the most important variables is surgical experience. For example, an experienced surgeon who has expertise in a traditional surgical approach may offer better outcomes than a surgeon who is using the latest technology and methods but has little experience.