Medical Apparatus: Imaging Guide to Orthopedic Devices

Orthopedic Devices

Fracture Fixation


Joint Arthroplasty - Introduction

Joint Arthroplasty - Shoulder

Joint Arthroplasty - Elbow

Joint Arthroplasty - Wrist and Hand

Joint Arthroplasty - Hip

Joint Arthroplasty - Knee

Joint Arthroplasty - Ankle and Foot


Joint Arthroplasty References

Fracture Fixation References





Joint Arthroplasty - Elbow

by Tim B Hunter, MD, MSc


Elbow Arthroplasty - Introduction

One of the biggest challenges in joint arthroplasty is elbow arthroplasty, because the forces transmitted across the elbow are amplified by the long lever arm of the forearm, and there is limited bone stock about the elbow. The main indications for elbow arthroplasty are similar to those for other joints including advanced osteoarthritis or inflammatory arthritis refractory to medical therapy. Indications also include complex fractures or nonunion of the distal humerus (Benjamin, 1994; Ferlic, 1999; Inglis, 1980). Absolute contraindications for elbow arthroplasty are systemic infection, elbow joint infection, or a neuropathic elbow joint. The goal of elbow joint arthroplasty is to decrease pain and restore a usable range of motion. Modern elbow arthroplasty designs and biomaterials have allowed elbow replacement surgery to become more accepted (Petscavage, 2012; Levin, 2019).

Arthrodesis of the elbow is a rare procedure that is also part of the surgical armamentarium for chronic elbow pain and disability. It is used for patients with advanced rheumatoid arthritis or patients with failed elbow arthroplasties who do not have adequate bone stock for revision surgery (Berquist, 1995; Ferlic, 1999). Radial head replacement is now more common and is used to treat complex radial head fractures. Capitellar arthroplasty is a newer technique for prevention of osteoarthritis and capitellar erosion in patients with a radial head prosthesis (Petscavage, 2012).


Total Elbow Arthroplasty

Unlike joint arthroplasty in the shoulder, hip, and knee, the main indication for total elbow arthroplasty (TEA) is rheumatoid arthritis rather than degenerative osteoarthritis. In general, prosthetic elbow replacement is avoided in younger patients, because there is an anticipated high rate of failure. The relatively poor bone stock about the elbow joint makes revision arthroplasty in the elbow considerably more difficult. Celli (2009) found semiconstrained total elbow arthroplasty in young patients was associated with a 22% revision rate. For these reasons, elbow arthroplasty is generally reserved for patients older than 40 (Petscavage, 2012).

The elbow has motion in flexion and extension as well as pronation and supination Three basic types of elbow arthroplasty are: a) constrained elbow arthroplasty; b) unconstrained or resurfacing elbow arthroplasty; and c) semiconstrained elbow arthroplasty (figure: total elbow prosthesis; figure: unconstrained elbow arthroplasty) (figure: semiconstrained elbow arthroplasty; figure: semiconstrained elbow arthroplasty; figure: Latitude EV elbow prosthesis).

A constrained elbow joint replacement consists of a rigid hinge constructed either with metal on metal or metal on high density polyethylene. The humeral and ulnar portions of the hinge are connected through a bushing and pin which do not allow varus-valgus motion. The radial head is often resected proximal to the annular ligament. The prosthetic humeral and ulnar stems are cemented into place, and the humeral condyles are resected.

The constrained prosthesis has increased stress at the elbow joint with high rates of osteolysis, loosening, and periprosthetic fractures. The constrained elbow arthroplasty is rarely used these days (Petscavage, 2012).

The semiconstrained elbow (sloppy hinge) prosthesis is the most commonly used total elbow arthroplasty (figure: semiconstrained elbow prosthesis; figure: semiconstrained elbow arthroplasty; figure Latitude EV elbow prosthesis; figure: Moonrad-Currey elbow prosthesis; figure: Nexel total elbow prosthesis). It is designed to help alleviate some of the loosening problems found with the constrained hinged prosthesis. The humeral and ulnar components are linked together with an axle and bushing arrangement which allows a degree of movement in the varus-valgus (coronal) plane, because there is a circular polyethylene ring which sits between the metal components to decrease friction and allow more movement (Berquist, 1995; Freiberg, 2001; Petscavage, 2012). Some modern elbow arthroplasties also incorporate prosthetic capitellar and radial head components into the design (figure: Latitude EV elbow prosthesis).

The humeral components of semiconstrained elbow prostheses are more prone to failure than the ulnar component. In the postoperative period, special attention should be given to anterior migration of the proximal end of the humeral prosthetic stem. Bone remodeling is also common at this location (Benjamin, 1994).

The unconstrained (unlinked) elbow prosthesis consists of separate humeral and ulnar metal components which articulate through a circular high-density polyethylene component (figure: unconstrained elbow arthroplasty). This design relies on the overlying soft tissues, rather than a bushing-axle linkage and pin, to maintain the articulation. The major complication associated with this implant is subluxation or dislocation at the joint itself, though this implant design has the lowest incidence of mechanical loosening from bone.

The elbow is particularly prone to heterotopic bone formation after immobilization or surgery. This complication is not uncommon after elbow prosthesis placement. It may be relatively benign, but it can lead to significant loss of joint mobility and require surgical removal (figure: semiconstrained elbow prosthesis with heterotopic bone formation).

Joint prosthesis infection is uncommon but a dreaded complication of elbow arthroplasty (figure: infected total elbow arthroplasty). Aseptic (non-infectious) prosthetic loosening is more common than prosthesis infection, but the differentiation between prosthesis infection with loosening and aseptic loosening is difficult to determine with imaging alone and may require surgical exploration if there are clinical findings suggesting an infection. While not common, periprosthetic elbow fractures may occur and should be looked for when evaluating radiographic studies of elbow prosthesis placement (figure: olecranon periprosthetic fracture).

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Elbow Hemiarthroplasty

Elbow hemiarthroplasty is an unusual procedure. There is replacement of one part of the elbow joint with a metallic prosthesis, usually replacement of the distal portion of the humerus (figure: elbow hemiarthroplasty) (Elbowdoc, 2015). The main indication is severe elbow trauma with a comminuted fracture of the distal portion of the humerus, effectively disrupting the elbow articular surfaces. The procedure is only recommended for elderly individuals or individuals who will be placing minimal demands on the elbow.


Radial Head Replacement (Arthroplasty)

Radial head replacement is most commonly performed for treatment of comminuted, complex radial head and neck fractures (Berquist, 1995). Radial head fractures represent 33% of all adult elbow fractures. Non-displaced partial fractures (Mason type 1) are treated non-operatively. Mason type 2 fractures representing partial marginal fractures involving a small part of the articular surface or with > 2mm of displacement are treated with open reduction and internal fixation (Ha, 2012). Comminuted fractures of the entire radial head (Mason type 3) and radial head fractures with radius dislocation (Mason type 4) are more difficult to treat.

Internal fixation with a plate and screws or radial head arthroplasty is preferred over radial head excision for those patients with comminuted, unstable fractures (Petscavage, 2012). Radial head arthroplasty if successful in this situation maintains elbow stability and range of motion by preserving the radius length and providing a functioning joint at the prosthetic radial head.

Silicone was used for the initial radial arthroplasties with the prosthetic radial head and neck component often made of Silastic (figure: silicone radial head arthroplasty; figure: various Silastic implants). With silicone products there is a high rate of failure with loosening, periprosthetic fracture, and silicone related synovitis. These types of arthroplasties are no longer being performed.

Currently radial head implants are composed of titanium, cobalt chromium alloy, or pyrocarbon. Pyrocarbon has an elastic modulus similar to cortical bone helping with bone stress transfer away from the radial head (Petscavage, 2012). Unipolar and bipolar designs are used. The unipolar design has a smooth stem either press fit or cemented into the proximal radius (figure: olecranon plate and screws and unipolar radial head prosthesis). The radial head itself centers on the native capitellum.

The bipolar design permits semiconstrained articulation between the prosthetic radial head and the fixed metal stem acting as the radial neck (figure: bipolar radial head prostheses; figure: Latitude EV bipolar radial head; figure: right bipolar radial head prosthesis). The articulation between the metal or pyrocarbon radial head and metallic stem is facilitated by a mobile polyethylene bearing at the head neck junction (Petscavage, 2012; Ha, 2012).

The main complications from radial head replacement are heterotopic bone formation about the elbow, secondary radiocapitellar osteoarthritis, and disengagement of the radial head implant (figure: right radial head prosthesis loosening). Periarticular fracture and infection are less common complications. The bipolar design may cause less long-term radiocapitellar osteoarthritis compared to the unipolar design. Ha (2012) and colleagues found that by 9 months after surgery 50% of radial head implants showed radiographic complications. Revision surgery or removal of the implant was required in 24% of the patients they studied.

"Overstuffing" can be a complication of radial head arthroplasty. This occurs when the vertical diameter of the radial head prosthesis is greater than the normal anatomic vertical diamater of the radial head. This can produce asymmetry of the medial and lateral ulnohumeral joint spaces and ultimately lead to failure of the radial head arthroplasty (Levin, 2019).

Sometimes capitellar resurfacing arthroplasty replaces the articular surface of the capitellum. A capitellar resurfacing arthroplasty is composed of cobalt chromium. It consists of a one piece unit with a peg to be press fit into the distal humerus and a convex, spherical articular surface to articulate with the radial head. Capitellar resurfacing arthroplasty is preventative to reduce the likelihood of capitellar osteoarthritis or erosion in patients with radial head deformation or a radial head arthroplasty (figure: radiocapitellar arthroplasty). Capitellar resurfacing arthroplasty may also be used by itself in patients with localized injury to the capitellar articular cartilage or localized malformation of the capitellum.

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Total elbow prosthesis   Semiconstrained elbow arthroplasty Elbow hemiarthroplasty
Total elbow prosthesis Semiconstrained elbow arthroplasty Elbow hemiarthroplasty Elbow hemiarthroplasty
A-constrained Stemmed design with hinged articulation. B-Resurfacing design with non-constrained (unconstrained) interface. from Benjamin, 1994 Image reproduced with permission from OrthoInfo. © American Academy of Orthopaedic Surgeons


(From Elbowdoc)
Unconstrained elbow arthroplasty Semiconstrained elbow arthroplasty Latitude EV total elbow prosthesis Coonrad-Murrey Total elbow prosthesis
Unconstrained elbow arthroplasty Semiconstrained elbow arthroplasty Latitude EV elbow prosthesis Total elbow prosthesis
From Kumar, 2015 (From Tornier). This prosthesis also incorporates a bipolar capitellar-radial head arthroplasty. Image used with permission From Zimmer Biomet.
Silicone replacement of radial head and neck   Radiocapitellar arthroplasty  
Radial head silicone prosthesis Radial head silicone replacement Left elbow radiocapitellar arthroplasty Left elbow radiocapitellar arthroplasty
    74 year-old woman with severe comminuted right radial head fracture treated by removal of the radial head and placement of a radiocapitellar arthroplasty.  
Olecranon plate and screws plus unipolar radial head prosthesis
Comminuted elbow fractures frontal view Comminuted elbow fractures lateral view Right elbow radial head prosthesis frontal view Right radial head prosthesis lateral view
35 year-old man who fell and sustained comminuted olecranon and radial head fractures. He was treated with olecranon plate and screws as well as a unipolar radial head prosthesis. Courtesy Lana Hirai Gimber, MD, MPH
Various type of Silastic (silicone) implants Bipolar radial head prosthesis, tension band wiring, and two Kirschner wires Bipolar radial head prosthesis
Various small Silastic implants Radial head prosthesis Left radial head prosthesis Left radial head prosthesis
from Benjamin, 1994 from Benjamin, 1994 57 year-old woman who sustained left radial head and neck fractures eventually treated by a bipolar radial head prosthesis.
Right bipolar radial head prosthesis with eventual prosthesis loosening
Right radial head prosthesis Right radial head prosthesis Right radial head prosthesis loosening Right radial head prosthesis loosening
57 year-old woman with radial head prosthesis and capitellar suture anchor. In 2011 she had a right elbow dislocation with a comminuted radial head fracture. A bipolar radial head prosthesis was placed to treat post-traumatic arthritis. Initial radiographs obtained in 2014 (left two images) showed the prosthesis to be well seated. Later radiographs in 2015 show prominent periprosthetic lucency around the prosthetic stem indicating non-infectious aseptic loosening. There are also chronic fractures of the proximal portions of the right radius and ulna.

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Semiconstrained left elbow arthroplasty with heterotopic bone formation Left elbow semiconstrained prosthesis with olecranon periprosthetic fracture Nexel Total Elbow Prosthesis
Elbow prosthesis and heterotopic bone Elbow prosthesis and heterotopic bone Left elbow prosthesis with olecranon periprosthetic fracture Zimmer Nexel Total Elbow Prosthesis
35 year-old woman with prior gunshot injury to left upper extremity. Multiple surgeries were performed to remove wooden fragments and shrapnel. Extensive heterotopic bone has developed about the left humerus and left elbow arthroplasty. Portions of previous fixation screws and plates are evident.   Image used with permission From Zimmer Biomet.
Infected total elbow arthroplasty with eventual placement of a revision total elbow arthroplasty
Infected left elbow prosthesis Infected left elbow prosthesis Revision total elbow arthroplasty Revision total elbow arthroplasty
66 year old man with infected left elbow arthroplasty. The arrows point to areas of periprosthetic lucency suggesting loosening which was found to result from an infected prosthesis. The patient had the prosthesis removed and underwent multiple subsequent surgeries with placement of a revision elbow arthroplasty.

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Joint Arthroplasty References


Author contact information

Tim Hunter

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