Uncemented Vs Cemented Hip Replacement
Total hip replacement surgeries are one of the most successful surgeries in terms of pain relief and gain of function. The majority of the hip arthroplasties done today in the USA are uncemented hip replacements. However, there is still an ongoing debate if uncemented hip replacement surgeries have better results both immediate and long term, as compared to cemented hip replacements.
Hip replacement surgeries involve placing a metallic stem (femoral component) inside the canal of the upper part of the thigh bone. A metallic head is placed on top of the femoral stem that duplicates the function of the natural head of the femur. Similarly, a metallic cup is placed in the natural socket of the hip joint formed by the acetabulum.
X-ray of the hip in lateral view showing a partial cemented hip replacement.
Cemented and uncemented hip arthroplasties differ in how the prosthetic implant is fixed to the natural bone. A cemented hip arthroplasty relies on bone cement to fix the implants to the bone interface. Uncemented hip replacements rely on bone on-growth over specially designed implants.
Cemented Hip Replacement
A cemented hip replacement uses a polymethylmethacrylate (PMMA) bone cement to fix the implant surface to the bone. The bone cement creates a grout and fixes the implant by acting as an interlocking surface between the implant and the bone rather than simply gluing the implant to the bone.
The bone cement is made by mixing powder and liquid components. The mixing and cementing techniques have evolved in the past decades to achieve maximum fixation. The modern mixing in the operating room involves the use of a vacuum mixer. The bone cement hardens in about 10 minutes in the OR temperature.
The modern technique of cementing involves:
- Preparation of the femoral canal using serial broaching and using a pulsatile lavage to wash the canal and remove debris.
- A cement restrictor is placed at an appropriate distance to prevent the cement from traveling down the canal.
- The cement is filled in the canal using a cement gun that pressurizes the cement injection in the canal. The gun ensures the cement is not eviscerated by the bleeding in the canal.
- The femoral stem is inserted to pressurize the cement and the tapered stem design ensures the cement pressure is maintained during the insertion. A proximal seal is made to ensure adequate pressure during the polymerization of the cement.
- The acetabulum cementing is rarely done but is similarly done to ensure adequate fixation. Beads may be used at the cement implant prosthesis to ensure an even cement distribution and to prevent bottoming out of the cement.
The cemented hip replacements are indicated only in limited cases:
- Osteopenic or osteoporotic patients have thin and porous bones. The porous bones may not support the uncemented implant due to poor bone ingrowth. A cemented implant has a better fixation as a result of cement penetration of the porous bone.
- Patients with a history of bone irradiation as a result of any malignancy who may need a hip replacement are best managed with a cemented hip replacement. The irradiated bone has poor potential for bone on-growth or bone in-growth.
- Patients with abnormally wide femoral canal are ill-suited for an uncemented hip replacement. The cement mantle ensures adequate fixation in patients with a wide femur (Dorr C).
Uncemented Hip Replacement
Uncemented hip replacement uses specially designed prosthetic components for the bone to implant fixation. The femoral component is usually covered with a porous surface on the upper end. The porous sprayed surface has microscopic contoured troughs and ridges.
The natural bone grows on and in the porous surface creating a gridlock that binds the implant to the bone. Uncemented fixation is the most common method of total hip replacement in the United states.
The operating surgeon prepares the bony femoral canal by broaching and inserting the implant slightly bigger than the final broach. The insertion of a slightly larger implant ensures a press-fit prosthesis that is snuggly fit.
X-ray showing an uncemented total hip replacement.
The acetabular component is mostly uncemented unless the patient has poor bone stock or has a history of irradiation. The fixation is usually aided with the screws that help secure the acetabulum shell in place until the bone ingrowth occurs. The uncemented type of fixation is the preferred type of fixation in elderly patients with a good bone stock, young patients, and in the setting of a revision hip replacement surgery.
Comparison of cemented and uncemented fixation
The uncemented prosthetic designs were advanced to overcome the complication faced with cemented fixations. Cemented fixation was liable to cement breakage and subsequent inflammation around the prosthesis. The breakage, micromotion, and inflammation may lead to implant loosening.
Bone cement implantation syndrome (BCIS) is a rare complication associated with cementing during joint replacement surgery. The cement material is hypothesized to travel in the bloodstream which may cause difficulty breathing, and cardiac arrest. Pulsatile lavage is aimed to prevent cement and fat globules from leaking into the bloodstream.
The uncemented fixation is not associated with BCIS and the cement osteolysis is not associated with uncemented methods. A well-positioned uncemented implant fixation gets stronger at the interface with time as bone ingrowth occurs, however, loosening may also be associated with uncemented stems.
With a setting time of 10 mins, the cemented implants are fixed instantaneously and patients are able to bear weight right after the surgery. However, in the case of uncemented stems, only partial weight-bearing is allowed initially as the bone ingrowth takes at least 3 months. However, with recent changes in implant designs and techniques, some surgeons may allow weight-bearing right after surgery even in uncemented fixations.
Positioning of the femoral stem is easier in cemented fixation as the stem position may be individually adjusted during cementing and stem insertion. However, in the case of uncemented fixation, the position is largely determined by the reaming and broaching of the femoral marrow.
There are numerous studies that compare the complications such as stress shielding, peri-prosthetic fractures, long-term survivorship, ease of revision, etc. between uncemented and cemented techniques with variable results.
The type of fixation used in hip replacement is largely determined by the patient’s individual hip anatomy, age, and any history of medical conditions. While cemented fixation is mainly done at the extremes of age, even these patients may be candidates for uncemented fixation depending upon their bone stock.
Do you have more questions?
What can patients do to maximize the lifespan of their knee replacement?
Following post-operative instructions, maintaining a healthy weight, staying active with low-impact exercises, and attending regular follow-up appointments with their orthopedic surgeon can all help prolong the life of a knee replacement.
Are there specific patient factors that make them better candidates for cemented or uncemented hip replacement?
Yes, certain patient factors such as age, bone quality, activity level, and underlying medical conditions may influence the suitability of cemented or uncemented hip replacement.
How does the longevity of cemented and uncemented hip replacements compare?
The longevity of cemented and uncemented hip replacements can vary, but studies have shown similar long-term outcomes for both types of procedures in appropriately selected patients.
Are there any differences in post-operative pain levels between cemented and uncemented hip replacements?
Post-operative pain levels may vary between cemented and uncemented hip replacements, with some studies suggesting less immediate post-operative pain with uncemented procedures due to reduced soft tissue trauma.
Can cemented and uncemented hip replacements be revised if necessary, and are there any differences in revision techniques?
Both cemented and uncemented hip replacements can be revised if necessary, with revision techniques tailored to the specific implant type and patient anatomy. Revision surgery may involve removing and replacing the implant components.
How do cemented and uncemented hip replacements differ in terms of surgical technique and recovery time?
Cemented hip replacements typically involve a shorter surgical time due to the immediate fixation provided by bone cement, while uncemented procedures may require longer surgical time for proper implant positioning and fixation. Recovery time may vary depending on individual patient factors.
Are there any differences in implant survivorship rates between cemented and uncemented hip replacements?
Implant survivorship rates, or the likelihood of the implant remaining in place without needing revision surgery, may be similar between cemented and uncemented hip replacements when appropriately selected and placed.
How does the risk of infection compare between cemented and uncemented hip replacements?
The risk of infection is generally low for both cemented and uncemented hip replacements when proper surgical techniques and infection prevention protocols are followed. However, some studies suggest a slightly higher risk of infection with uncemented procedures.
Can patients with osteoporosis undergo uncemented hip replacement surgery, or are there limitations?
Patients with osteoporosis can undergo uncemented hip replacement surgery, but careful consideration is needed to ensure adequate bone quality for implant fixation and stability.
Are there any limitations on physical activities or weight-bearing restrictions following cemented or uncemented hip replacement surgery?
While early post-operative weight-bearing restrictions may vary depending on surgical technique and implant fixation, most patients can gradually resume normal activities and weight-bearing as tolerated with guidance from their healthcare provider.
What are the risks of complications such as implant loosening or fracture with cemented and uncemented hip replacements?
The risks of complications such as implant loosening or fracture are generally low for both cemented and uncemented hip replacements when performed by experienced surgeons using appropriate techniques and implants. However, these risks can vary depending on individual patient factors.
How does the cost of cemented and uncemented hip replacement surgery compare, including initial expenses and long-term considerations?
The cost of cemented and uncemented hip replacement surgery can vary depending on factors such as implant type, surgical technique, hospital fees, and post-operative care. Initial expenses may differ, but long-term considerations such as revision surgery rates can impact overall costs.
Can patients with metal allergies undergo cemented or uncemented hip replacement surgery, and are there implant options available to accommodate allergies?
Patients with metal allergies can undergo cemented or uncemented hip replacement surgery with careful consideration of implant material composition. Alternative implant options such as ceramic or titanium may be available to accommodate metal allergies.
How do cemented and uncemented hip replacements differ in terms of implant stability and longevity in the younger population?
In younger patients, uncemented hip replacements may offer potential advantages in terms of bone preservation and longevity, as they rely on bone ingrowth for fixation and may facilitate future revision surgery if needed. However, long-term studies comparing outcomes between cemented and uncemented implants in younger patients are needed.
Are there any specific risks or complications associated with cemented or uncemented hip replacement surgery in obese patients?
Obese patients undergoing cemented or uncemented hip replacement surgery may face increased risks of complications such as wound healing problems, infection, implant loosening, and joint instability. Preoperative optimization and careful surgical planning are essential to minimize these risks.
Can patients with a history of previous hip surgeries undergo cemented or uncemented hip replacement surgery, and does the surgical history impact implant selection?
Patients with a history of previous hip surgeries can undergo cemented or uncemented hip replacement surgery, but the surgical history may influence implant selection and surgical approach. Careful assessment of previous surgical outcomes and bone quality is necessary to optimize implant fixation and stability.
How does the choice between cemented and uncemented hip replacement surgery impact rehabilitation protocols and post-operative care?
Rehabilitation protocols and post-operative care may vary slightly depending on the type of hip replacement surgery performed, with considerations for early weight-bearing restrictions, activity modifications, and physical therapy goals.
Can patients with compromised bone quality, such as those with osteoporosis, undergo cemented or uncemented hip replacement surgery, and are there any considerations for implant selection?
Patients with compromised bone quality, including osteoporosis, can undergo cemented or uncemented hip replacement surgery with careful consideration of implant selection and fixation techniques. Options such as cement augmentation or specialized implants may be considered to optimize stability and longevity.
How do patient age and activity level influence the decision between cemented and uncemented hip replacement surgery?
Patient age and activity level are important factors in the decision-making process for cemented versus uncemented hip replacement surgery. Younger, more active patients may benefit from uncemented implants, which offer potential advantages in bone preservation and long-term durability.
Are there any differences in the risk of complications such as dislocation or leg length discrepancy between cemented and uncemented hip replacement surgery?
The risk of complications such as dislocation or leg length discrepancy may vary between cemented and uncemented hip replacement surgery, depending on factors such as surgical technique, implant selection, and patient-specific variables. Surgeons take these factors into account to minimize the risk of complications during surgery.
My name is Dr. Suhirad Khokhar, and am an orthopaedic surgeon. I completed my MBBS (Bachelor of Medicine & Bachelor of Surgery) at Govt. Medical College, Patiala, India.
I specialize in musculoskeletal disorders and their management, and have personally approved of and written this content.
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