Metal Plates in Knee Surgery: Purpose, Types, Procedures, and Recovery

What is the metal plate in knee surgery?

A metal plate in knee surgery is a specialized orthopedic implant primarily used to stabilize bone fractures around the knee joint or to maintain alignment following corrective bone cuts (osteotomies), promoting proper healing and restoring structural integrity.

Understanding Orthopedic Implants in Knee Surgery

Orthopedic surgery often relies on the use of internal fixation devices to support bones during their healing process. While many people associate knee surgery with total joint replacement, which involves comprehensive prosthetic components, metal plates serve a distinct and vital role. These plates, along with screws, are a common form of internal fixation, designed to hold bone fragments in precise alignment or to maintain the corrected position of bones after a surgical cut.

Primary Role and Purpose of Metal Plates

The fundamental purpose of a metal plate in knee surgery revolves around providing stability and facilitating optimal bone healing.

• Stabilization and Fixation: Plates are rigid structures applied to the surface of a bone (or across a fracture site) and secured with screws. Their primary role is to provide strong internal fixation for:
  • Fractures: Particularly complex or unstable fractures involving the tibia (shin bone) near the knee (tibial plateau fractures) or the femur (thigh bone) just above the knee (distal femoral fractures). The plate holds the broken pieces together, preventing movement that could disrupt healing.
  • Osteotomies: Surgical procedures where a bone is cut and reshaped to correct alignment issues, often to shift weight bearing away from damaged cartilage in an arthritic knee. The plate maintains the new, corrected angle of the bone as it heals.
• Weight Bearing: By providing a stable internal scaffold, plates allow for controlled, and sometimes early, weight bearing on the limb, which can be crucial for rehabilitation and preventing muscle atrophy.
• Healing Promotion: A stable environment is critical for bone healing (union). Plates create this stability, allowing the body's natural healing mechanisms to bridge the gap in a fracture or fuse the bone segments after an osteotomy.

Types of Metal Plates Used in Knee Surgery

The design and material of metal plates vary based on the specific anatomical location and biomechanical demands.

• Fracture Plates: These are designed to conform to the contours of specific bones and provide robust fixation for broken bones.
  • Locking Plates: Feature screw holes that "lock" the screws into the plate, creating a fixed-angle construct. This provides enhanced stability, particularly in osteoporotic bone or comminuted fractures, by distributing load over a larger area rather than solely relying on friction between the plate and bone. Common examples include Locking Compression Plates (LCP) and anatomically pre-contoured plates for the tibial plateau or distal femur.
  • Non-locking Plates: Screws pass through the plate but do not lock into it, relying on compression between the plate and bone for stability. Dynamic Compression Plates (DCP) are an example, designed to allow for axial compression across a fracture.
  • Buttress Plates: Often used for tibial plateau fractures, these plates provide support against shear forces, preventing the collapse of the articular (joint surface) fragments.
• Osteotomy Plates: Specifically designed to maintain the precise angular correction achieved during an osteotomy.
  • High Tibial Osteotomy (HTO) Plates: Used for correcting varus (bow-legged) deformities, shifting weight from the medial (inner) compartment of the knee.
  • Distal Femoral Osteotomy (DFO) Plates: Used for correcting valgus (knock-kneed) deformities, shifting weight from the lateral (outer) compartment.
• Materials: Modern orthopedic plates are typically made from biocompatible metals that are strong, durable, and resistant to corrosion within the body.
  • Stainless Steel: A traditional material, strong and cost-effective.
  • Titanium and Titanium Alloys: Increasingly common due to their superior biocompatibility, lighter weight, and excellent strength-to-weight ratio. They are also non-ferromagnetic, making MRI imaging safer and clearer.

Surgical Procedures Involving Metal Plates

Metal plates are integral to several key orthopedic procedures around the knee.

• Fracture Fixation:
  • Open Reduction Internal Fixation (ORIF): Involves surgically opening the skin to directly visualize the fracture, manually realign the bone fragments (reduction), and then fix them in place with a plate and screws.
  • Minimally Invasive Plate Osteosynthesis (MIPO): Utilizes smaller incisions and specialized instruments to slide the plate under the skin and muscle without extensively exposing the fracture site. This approach aims to preserve blood supply to the bone, potentially leading to faster healing and fewer complications.
• Osteotomy: These procedures are performed to realign the leg, often to delay or avoid total knee replacement by preserving the natural joint. After the bone cut is made, a plate is used to stabilize the new alignment until the bone heals in its corrected position.

Advantages and Considerations of Plate Fixation

While highly effective, the use of metal plates comes with distinct advantages and potential considerations.

• Advantages:
  • Strong Internal Fixation: Provides robust stability, crucial for complex fractures and osteotomies.
  • Early Mobilization Potential: The stability offered often allows for earlier, controlled movement and weight bearing, which aids in rehabilitation and prevents joint stiffness.
  • Improved Healing Rates: By maintaining precise alignment and stability, plates create an optimal environment for bone union.
• Considerations/Potential Complications:
  • Infection Risk: As with any surgery, there is a risk of infection around the implant.
  • Non-union or Malunion: Despite the plate, bone may fail to heal (non-union) or heal in an incorrect position (malunion), requiring further intervention.
  • Hardware Irritation/Pain: The plate or screws can sometimes cause discomfort, rub against soft tissues, or become palpable under the skin, leading to pain.
  • Need for Hardware Removal: In some cases, particularly if irritation occurs, the plate may need to be removed after the bone has fully healed in a secondary surgery.
  • Stress Shielding: The plate can bear some of the load that the bone would normally carry, potentially leading to a decrease in bone density beneath the plate.
  • Implant Failure: Although rare, the plate or screws can break or loosen, especially if the bone does not heal properly.

Rehabilitation and Recovery with a Metal Plate

Rehabilitation after knee surgery involving a metal plate is critical for optimal outcomes and typically involves a structured physical therapy program.

• Immediate Post-Op: Focus on pain management, swelling control (RICE - Rest, Ice, Compression, Elevation), and protecting the surgical site.
• Early Phase: Gentle range of motion exercises are initiated, often with strict limitations on weight bearing (non-weight bearing or partial weight bearing) as prescribed by the surgeon. The goal is to prevent stiffness without stressing the healing bone.
• Progressive Loading: As healing progresses, a gradual increase in weight bearing is introduced. Strengthening exercises for the quadriceps, hamstrings, and calf muscles become a focus.
• Functional Training: Later stages involve exercises to restore balance, proprioception, and functional movements necessary for daily activities, work, or sports.
• Importance of Physical Therapy: A skilled physical therapist will guide the patient through each phase, ensuring appropriate progression, monitoring healing, and addressing any limitations. Adherence to the rehabilitation protocol is paramount for successful recovery.

When is a Metal Plate Removed?

The decision to remove a metal plate is made on a case-by-case basis after the bone has fully healed, which can take anywhere from 6 months to over a year.

• Indications for Removal:
  • Pain or Irritation: The most common reason, often due to the plate or screws rubbing against tendons, muscles, or nerves.
  • Infection: If an infection develops around the implant.
  • Prominent Hardware: When the plate is easily felt under the skin and causes discomfort, especially with clothing or during certain activities.
  • Activity Level: In young, active individuals, removal may be considered to prevent potential complications during future high-impact activities, though this is less common for plates than for other hardware like intramedullary nails.
• Factors Influencing Decision: Patient age, overall health, activity level, location of the plate, and the potential risks versus benefits of a second surgery are all considered.
• Procedure: Hardware removal is generally a less complex procedure than the initial surgery, but it still carries risks such as infection or damage to surrounding tissues.

Conclusion: The Role of Plates in Restoring Knee Function

Metal plates are indispensable tools in modern orthopedic knee surgery, offering robust internal fixation for fractures and precise alignment correction for osteotomies. By providing the necessary stability, these implants facilitate the body's natural healing processes, allowing patients to embark on a structured rehabilitation journey towards restoring function, reducing pain, and improving their overall quality of life. Understanding their purpose, application, and the commitment required for rehabilitation is key for anyone undergoing such a procedure.