Current Advances in Total Elbow Arthroplasty: A Comprehensive Clinical Review

Indications for Elbow Arthroplasty

The elbow is a necessary joint for normal functioning in daily life, yet it is susceptible to various degenerative conditions and traumatic lesions or posttraumatic sequelae. In contrast to other joints, such as the hip or knee, elbow function cannot be easily replaced or bypassed by external aids.^[1] In the past, multiple solutions have been used to solve the problem of painful, stiff, or flail elbows.

The elbow joint combines two rotatory axes using three joints: flexion/extension by the humeroulnar and humeroradial joints, and pronation/supination by the radioulnar and humeroradial joints.

Osseous stability depends on the degree of flexion of the elbow.^[3] In complete extension, the boney prominence on the upper end of the ulna, the olecranon, ensures stability by docking into the olecranon fossa. At approximately 30° of flexion, the elbow has the least osseous stability. In maximal flexion, the coronoid process engages in the coronoid notch and accounts for stability. In addition to providing osseous stability, collateral ligaments aid in varus/valgus stability during flexion and extension, especially where osseous stability is lacking.

When elbow function for adequate performance of activities of daily life is compromised, elbow arthroplasty may be a good option, especially in the low-demand elderly patient. Today, the most frequent indications for the procedure are to treat the sequelae of long-standing, degenerative disease—ie, rheumatoid arthritis, which accounts for 25% of total elbow arthroplasties, and posttraumatic conditions, which account for 62%.^[Secondary osteoarthritis, accounting for 7% of elbow arthroplasties, is more common than primary osteoarthritis of the elbow.In recent decades, indications for elbow arthroplasty have shifted from rheumatoid arthritis toward trauma, as improved disease-modifying antirheumatic drugs have become available.

The use of elbow arthroplasty for primary management of comminuted elbow fractures is rising, because the procedure produces better long-term results than several decades ago.

Elbow arthroplasty can be an option in oncologic surgery when resection of primary or secondary cancer is necessary.

Depending on the exact location of the elbow-related problem, various options are available as treatment (Table).

Table. Treatment Options for Elbow-Related Problems

Affected joint(s)	Options	Plain radiographs
Radial head	Radial head replacement	Figure 1
Ulna	Total elbow arthroplasty	Figure 2
Humeroradial	Radial head replacement	Figure 1
Humeroradial	Unicompartmental replacement Figure 3
Humeroulnar	Total elbow arthroplasty	Figure 2
Humerus	Hemiarthroplasty	Figure 4
Radioulnar	Radial head replacement Figure 1
Radioulnar

Figure 1. Radial head replacement.

Figure 3. Unicompartmental replacement.

Figure 2. Total elbow arthroplasty.

Figure 4. Hemiarthroplasty

Absolute contraindications include general orthopedic issues, such as active infection (local or systemic), inability to undergo general anesthesia, paralysis of the arm, and inadequate postoperative soft-tissue coverage.

Relative contraindications include young age, because younger patients tend to put high-demand stress on the elbow joint by participating in sports and other activities, and diabetes and smoking, because either of these conditions might compromise wound healing. In addition, walking with crutches during rehabilitation may be problematic for patients who have had elbow arthroplasty.

Furthermore, possible implant-specific long-term complications influence decision-making on the part of the surgeon. Radial head prostheses may lead to excessive wear of and pain in the capitellum.^[8] Hemiarthroplasty does not replace the ulna and radius, which may lead to painful degeneration of these native articulating surfaces.^[9] Unicompartmental arthroplasty relieves only pronation/supination problems, and has only a slight effect on flexion/extension.

In total elbow arthroplasty, two main models are currently available: linked and unlinked designs. Linked (or semi-) constrained elbows have a mechanical connection between the humeral and ulnar components that prevents disassociation. These implants do not rely on muscular or ligamentous tissues for stability.

Unlinked implants have no physical connection between the humeral and ulnar components. They rely on bearing surface architecture as well as soft-tissue integrity for elbow stability.

Unlinked total elbow arthroplasty consists of two separate implants and relies more on ligamentous stability, as opposed to linked arthroplasties, which have more intrinsic stability. This difference implies that unlinked arthroplasties are less suitable in patients with severe ligamentous instability, as seen in long-standing rheumatoid arthritis, because of a high dislocation rate. In these cases, the use of linked designs is advisable.

In one modern design—the latitude total elbow arthroplasty—it is possible to decide during surgery whether to use a linked or unlinked version of the implant because this prosthesis offers an optional part for constrainment of the hinge.

The inherent stability of the linked designs may result in higher forces being transferred across the implant/cement and cement/bone interfaces. This is why modern designs use a “sloppy” hinge, having 7°-10°⁰ varus/valgus inherent laxity at the hinge section, with a minimal motion-bearing contact area; this aims to maintain intrinsic stability without the risk for early loosening.

The fixation technique may be cemented or uncemented, with a bone-ingrowth coating. Cemented designs have the advantage of instant fixation, which might be favorable in the linked designs regarding the previously mentioned pulling-out forces. However, a long cement mantle may result in elaborate surgery if revision is necessary.

Considerations for Periprocedural Care

Regarding the affected joint and patient symptoms, pain relief and/or enhancement of range of motion should be pursued, depending on the patient’s expectations and wishes. It is also necessary to inform patients that even though a joint is replaced, it can never reach the level of a healthy native joint. Therefore, activities should be adapted, and high-impact forces avoided, to decrease the chance of the implant loosening or of periprosthetic fractures. For example, patients with a total elbow arthroplasty are advised not to lift more than 5 kg at once, although this is based on empirical experience; no trials on use and the impact of use on implant survival have been published.

Postoperative short-term follow-up is important for checking on wound healing and preventing acute infections. In a 6- to 8-week period of functional rehabilitation, patients generally have fair success at pursuing activities of daily living. Long-term follow-up is important to monitor chronic problems, such as implant loosening, and systemic disease, such as rheumatoid arthritis. Especially in unlinked arthroplasties, polyethylene bushing or inlay wear and metal wear of the humeral and/or ulnar prosthesis pose a problem, because the articulating surfaces are larger than in linked designs; unlinked models have a large articulating area and not only a small hinge surface. As such, taking a patient history, physically examining the patient’s elbow for range of motion and stability, and having the patient complete a standardized questionnaire on elbow function using the patient-reported outcome measures are now routine care.

Triceps-On and Triceps-Off Techniques

To achieve good intra-articular exposure, two approach techniques can be distinguished: triceps-on and triceps-off. The triceps-on technique without olecranon osteotomy leaves the patient with a larger range of motion postoperatively, with no additional complications, even though the surgical exposure of the operative field is technically more challenging.^[14]

The triceps-on Bryan-Morrey approach is performed by making a window medial to the distal triceps tendon.^[15] A variant to this approach uses windows on both sides of the triceps.^[14] Another triceps-sparing approach is to perform a chevron osteotomy and to reattach the osseous insertion of the triceps afterwards.

Triceps-off approaches use subperiostal dissection of the triceps insertion and refixation using tension band wiring. It is also possible to dissect the triceps muscle longitudinally along the muscle fibers and to approach the elbow joint posteriorly.

Ideally, triceps function is protected as much as possible to aid in postoperative rehabilitation and prevention of a flexion contracture.

In radial head arthroplasty, it is necessary only for the humeroradial articulation to be exposed. Three usual approaches can be distinguished, with many variations possible, depending on the individual need.

The first is the posterolateral or Kocher approach, as described by Theodor Kocher in 1892.
This approach uses the interval between the anconeus and muscles, which leads to the lateral side of the radial head and proximal radius. To achieve a wider exposure, the extensor carpi ulnaris at the point of origin on the humerus or the insertion of the anconeus muscle where it inserts distally on the posterior surface of the ulna can be dissected. During this approach, the lateral collateral ligament is at risk to be damaged or lifted off of the ulna because of the subperiostal dissection.

The second approach, the anterolateral or Kaplan approach, uses the interval between the extensor carpi ulnaris and extensor digitorum communis anterior to the Kocher approach.
During this approach, the posterior interosseous nerve (PIN) shifts during pronation and supination. Therefore, to turn the PIN anteriorly, this approach is performed with the forearm in pronation.

Third, the Boyd approach uses the ulnar insertion of the anconeus and supinator muscles as an en bloc flap, which protects the PIN.However, the dorsal recurrent artery is at risk to be damaged during reflection of the muscles.

Short- and Long-Term Complications

The most serious short-term complications are neurovascular injury, wound healing problems, infection, and dislocation.Good wound hygiene lowers the superficial infection rate, and sterile surgery, combined with antibiotic-loaded cement, decreases the rate of deep periprosthetic infections.

In the long term, loosening of the implant on either an septic or aseptic basis is the main cause of device failure.^[11] In radial head replacement and hemiarthroplasty, the opposing articular bone quality must be evaluated to monitor erosion.

Implant survival rates are implant-specific, yet several trends are distinguishable. Total elbow arthroplasties currently have a mean 10-year survival rate of approximately 90%, which is an increase over previous decades. Radial head prostheses have good long-term results, but large implant registry data are lacking.

Radiohumeral arthroplasties have no long-term follow-up results but seem to show good 5-year results in selected patients.

Conclusion

Especially in the past four decades, significant advances have been made in elbow arthroplasty. However, owing to the relatively small numbers of patients requiring elbow arthroplasty, regardless of type, effective treatment modalities require ongoing research. To ensure optimal patient care, elbow problems are best treated in orthopedic clinics where the surgeons are expert in performing arthroplasties.