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
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).
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 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. 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.
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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|Semiconstrained left elbow arthroplasty with heterotopic bone formation
||Left elbow semiconstrained prosthesis with olecranon periprosthetic fracture
||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
|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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