Radial Head Arthroplasty

Introduction

The radial head is a critical component of the elbow joint, situated at the top of the radius bone in the forearm. This small, disk-shaped structure plays a major role in the stability and function of the elbow. It assists in transmitting forces from the hand to the upper arm and contributes to smooth movements of the forearm, particularly during rotation. Injuries to the radial head can significantly impact elbow function. Radial head fractures make up about 5.4 percent of all fractures. These fractures usually happen when someone falls on their outstretched arm with their palm facing down.

What Is Radial Head Arthroplasty?

Radial head arthroplasty (RHA) surgery replaces a damaged or severely fractured radial head in the elbow joint. This complicated operation removes the damaged radial head and replaces it with an artificial implant. RHA is usually thought about when other treatments like fixation or excision are impossible or have not worked. RHA aims to make the elbow joint stable again, reduce pain, and improve function, especially for people who have injured their elbow due to accidents or injuries.

What Are the Indications for Radial Head Arthroplasty?

Radial head arthroplasty is considered in patients who present with a variety of conditions:

• Acute radial head fracture.

• Complex elbow dislocation.

• Comminuted and reconstructable fractures.

• Posttraumatic arthritis of the radiocapitellar joint.

• Nonunion and malunion.

• Failed previous attempts at radial head reconstruction.

What Are the Contraindications for Radial Head Arthroplasty?

Contraindications for radial head arthroplasty (RHA) include

• Repairable Fracture - RHA should not be done if the radial head fracture can be fixed or repaired using other methods.

• Active Infection - If there is an ongoing infection in the elbow joint, RHA is not advisable until the infection is treated and resolved.

• Capitellar Arthrosis - Having arthritis in the capitellum (the part of the humerus bone that interacts with the radial head) is a relative contraindication.

What Are the Surgical Techniques and Steps in Radial Head Arthroplasty?

Several surgical techniques are employed in radial head arthroplasty, each with its advantages and considerations. The choice of technique depends on factors such as the patient's condition, the surgeon's expertise, and the type of implant selected.

The two primary surgical approaches are

• Open Approach - This traditional approach involves a large incision to access the radial head. It provides excellent visualization of the joint but may result in more tissue damage and scarring.

• Minimally Invasive Approach - Utilizing smaller incisions and arthroscopic assistance, minimally invasive techniques aim to minimize tissue disruption while achieving the same surgical objectives.

The surgical steps for RHA typically include the following.

• After accessing the radial head, the surgeon carefully resects the damaged or fractured radial head.

• The choice of implant varies and may include modular, monoblock, or bipolar implants. These are securely fixed into the proximal radius with cement or press-fit techniques.

• The surrounding soft tissues, including the annular ligament and the capsule, are repaired to restore stability and function.

• Post-surgery, an essential component of RHA, is a tailored rehabilitation program that focuses on range of motion, strength, and gradual return to functional activities.

How Is Rehabilitation After Radial Head Arthroplasty Done?

Recovery time after radial head arthroplasty can vary, but most patients can expect to regain significant function within 3 to 6 months.

• Isolated Radial Head Fracture - After RHA for a simple radial head fracture, the patient wears a splint for seven to 10 days. Then, they start moving their elbow actively and with some assistance. They can also do pronation and supination (rotating the forearm) with the elbow bent at 90 degrees. If, after six weeks, there's still limited motion or strength, formal therapy is considered.

• Elbow Instability - For cases involving elbow instability, the elbow is moved within a stable range for 2 to 3 weeks post-surgery, and then unrestricted motion is allowed.

What Are the Different Implant Choices in Radial Head Arthroplasty?

Implant selection is critical in radial head arthroplasty, as it significantly influences surgical outcomes.

Types of Implants for RHA:

• Loose-Fitting Stems - Some RHA implants are designed to be "loose-fitting," meaning they have modular components for the head, neck, and shaft. These implants settle into an anatomically correct position, acting as a spacer to stabilize the elbow. They are thought to offer better articulation with the capitellum (part of the humerus), allowing for a smoother range of motion.

• Press-Fit Stems - Press-fit stems are designed to fit into the bone's canal tightly. These implants are also modular and mimic the natural shape of the radial head. They offer initial stability, but excessive stress from oversizing can lead to radial shaft fractures.

• Bipolar Prosthesis - Bipolar RHAs have articulation in the head-neck junction, allowing better movement between the radial head component and the capitellum. While they can offer improved stability and motion, they have been associated with a unique complication called dislocation of the prosthesis.

• Pyrocarbon Prosthesis - This type of implant uses pyrolytic carbon combined with a titanium alloy stem. It is believed to transmit loads more like natural bone and may cause less wear on the capitellum over the long term.

• Radiocapitellar Hemiarthroplasty - This is used in patients with radiocapitellar arthritis, non-reconstructable capitellar fractures, or capitellar osteonecrosis. It can involve implants designed specifically for the capitellum and may be combined with other radial head implants for comprehensive elbow reconstruction. Results of RCH are still emerging, and more research is needed to assess its effectiveness.

What Are the Complications Associated With Radial Head Arthroscopy?

Complications can occur following radial head surgery, but they are not exclusive to this procedure and can be influenced by the elbow's traumatic history.

• After surgery, certain individuals might encounter a sensation of reduced flexibility or restricted movement (stiffness) in their elbow.

• Pain is a potential complication, which can result from the surgery itself or other factors related to the elbow.

• Ulnar nerve issues can occur, possibly due to the surgical procedure.

• PIN (Posterior Interosseous Nerve) palsy is a condition that may arise if there is excessive pressure on the radial neck during surgery.

• Heterotopic ossification or abnormal bone growth in the elbow region can happen.

• Some implants may show radiolucencies (dark areas on X-rays) around the stem, but it is unclear if this leads to forearm pain.

• With longer follow-ups, erosion of the capitellum (part of the humerus) can occur due to differences in implant material compared to natural cartilage.

• Filling the radial head with too much material can speed up capitellar erosion.

• Bipolar prostheses can be more prone to dislocation, a unique complication that needs careful monitoring.

Conclusion

Radial head arthroplasty has become a valuable surgical option for patients with radial head fractures, complex elbow instability, and other related conditions. When performed by experienced hands and supported by comprehensive rehabilitation, RHA can be highly successful, providing patients with hope for a pain-free and functional elbow joint.