Bone Cement: Uses, Types, and Advantages

Bone cement plays a vital role in modern joint replacement and bone stabilization surgeries. Originally developed for dental applications, it has become a standard material in orthopedic procedures due to its ability to securely anchor implants and support bone healing. In this article, we aim to explain what orthopedic bone cement is, its types, advantages, and applications, including its use in spine surgeries such as vertebroplasty and kyphoplasty.

What is Bone Cement?

Orthopedic bone cement is a specialized chemical compound, most commonly made from acrylic materials, designed to anchor implants in joint replacement surgeries or to stabilize fractured or weakened bones. By providing reliable mechanical support, bone cement plays a crucial role in ensuring proper stability and accelerated healing after surgical procedures.

Historically, acrylic cement was initially developed for dental applications, but its potential in orthopedics was realized when it was first used in joint replacement surgery in England in 1960. Since then, it has become an essential tool in modern orthopedic practice.

Advantages and Disadvantages of Bone Cement

The advantages and disadvantages of bone cement can be summarized as follows:

Advantages

• Fills gaps between the implant and bone, providing a secure fit; minor deviations during surgery are typically negligible.
• Enhances the mechanical stability of the operated joint, facilitating faster and more effective recovery.
• Provides lateral support to the joint, improving overall joint strength and function.

Disadvantages

• Sudden drops in blood pressure may occur in some patients
• Risk of postoperative infections
• Joint inflammation

Note: Orthopedic surgeons routinely prescribe antibiotics after joint replacement surgeries to minimize infection risk.

Visibility on X-rays

Bone cement is visible on radiographic examinations. In patients with hip prostheses, a radiolucent line may sometimes appear within the cement, indicating the location of a fracture or interface between the cement and bone.

Antibiotic-Loaded Bone Cement

Bone cement can be loaded with antibiotics for prophylactic purposes. Typical doses range from 0.5 to 2 g of antibiotics per 40 g of PMMA. Antibiotic-loaded cements help prevent postoperative infections without significantly affecting the mechanical properties of the cement.

Longevity

Long-term studies indicate that implants secured with orthopedic bone cement can last 10–20 years longer than non-cemented alternatives. This demonstrates the durability and reliability of cemented implants in orthopedic surgery.

Types of Bone Cement

Bone cements can be broadly categorized into polymer-based and ceramic-based types:

1-Acrylic Cement (PMMA-Based)

• The most commonly used cement for hip and knee replacements.
• Composed of PMMA powder and MMA monomer, which self-polymerizes after mixing.
• Pore size and distribution are critical for mechanical strength; large pores weaken the cement.

2-Polypropylene Fumarate (PPF)-Based Cement

• Biodegradable, biocompatible polyester cement suitable for skeletal defects.
• Crosslinked PPF cements can support bone growth and provide adequate compressive strength.

3-Calcium Phosphate Cement (CPC)

• Consists of solid phases (e.g., tetra calcium phosphate and dicalcium phosphate) mixed with a liquid to form hydroxyapatite.
• Biocompatible, neutral pH (~7), and supports bone formation.
• It can be molded or injected into bone defects before or during setting.

4-Glass Ionomer Cement (GIC)

• Ceramic-based cements are primarily used in dentistry, but also applicable in orthopedics.
• Formed by combining polyacrylic acid with fluorine aluminosilicate.
• Provides strong adhesion between bone and metallic implants.

Vertebroplasty and Kyphoplasty: Bone Cement in Spine Surgery

Vertebroplasty and kyphoplasty are minimally invasive procedures used to treat vertebral compression fractures, which are commonly caused by osteoporosis, trauma, or tumors. In both procedures, bone cement is injected into the fractured vertebra to stabilize it, relieve pain, and prevent further collapse.

During the procedure, the patient is positioned on the operating table, and real-time imaging, such as fluoroscopy or CT, is used to accurately locate the damaged vertebra. A thin needle is then inserted through a small skin incision into the vertebral body. In certain cases, a small bone sample may be collected for diagnostic purposes.

In kyphoplasty specifically, a balloon is inserted through the needle and gently inflated to restore vertebral height and create a cavity for cement injection. Once the desired space is achieved, the balloon is deflated and removed, and bone cement is carefully injected into the vertebral cavity. The cement hardens within minutes, providing structural support and stabilizing the vertebra. Imaging is repeated to confirm proper cement placement and vertebral stability.

While vertebroplasty involves direct cement injection without creating a cavity, kyphoplasty restores vertebral height in addition to stabilizing the fracture. The primary goals of these procedures are pain relief, improved mobility, stabilization of the fractured vertebra, and prevention of further spinal deformity. In rare cases where the vertebral damage is extensive, prosthetic implants or open surgery may be required to achieve optimal outcomes.

Indications for Vertebroplasty and Kyphoplasty

The indications for vertebroplasty and kyphoplasty include:

• Painful osteoporotic fractures unresponsive to conservative treatment after ~3 weeks
• Painful benign vertebral tumors (e.g., hemangioma, giant cell tumor)
• Pain relief in malignant vertebral lesions (palliative only)

Complications of Cement Injection

Although complications are rare, potential risks include:

• Cardiac events (heart attack, cardiac arrest)
• Stroke or embolism (blood or fat)
• Infection
• Cement leakage into the surrounding tissue or blood vessels, potentially causing nerve damage or organ injury

Note: With experienced surgeons, serious complications are uncommon, and the procedure is generally safe.

Conclusion

Orthopedic bone cement is a versatile and essential material in modern orthopedic surgery, providing stability, supporting implant fixation, and enhancing patient recovery. Its various types offer tailored solutions for different clinical needs. Minimally invasive procedures such as vertebroplasty and kyphoplasty further demonstrate the critical role of bone cement in stabilizing vertebral fractures and alleviating pain, improving both function and quality of life for patients.