Elbow Instability

Modern Study Review (AI-Generated)

High-Yield Summary

Complex elbow instability involves disruption of the ulnohumeral articulation, collateral ligaments, and often the radial head and coronoid process. Restoration of stability prioritizes the ulnohumeral joint, followed by radial head repair or replacement, and ligamentous reconstruction. Modern management emphasizes early motion within a protected arc using hinged external fixation to optimize functional outcomes and minimize stiffness.

Key Diagnostic Findings

Anatomy

• Primary stabilizer: Ulnohumeral articulation (proximal ulna and trochlea).
• Secondary stabilizers: Radial head and medial collateral ligament (MCL).
• Coronoid process: Critical for anterior stability; at least 50% of the coronoid should be preserved or reconstructed.
• Ligaments: MCL and lateral collateral ligament complex provide ~50% of varus-valgus stability; articular congruity and anterior capsule contribute the remainder.

Clinical Presentation

• History of trauma with elbow dislocation or fracture-dislocation.
• Pain, swelling, and instability, especially with valgus or varus stress.
• Limited range of motion, often with mechanical block or apprehension.
• Neurovascular exam essential to rule out nerve injury (ulnar nerve commonly affected).

Imaging

• X-rays: AP, lateral, and oblique views to assess ulnohumeral alignment, radial head fractures, coronoid fractures, and dislocation.
• CT scan: Detailed evaluation of coronoid fractures and radial head comminution.
• MRI: Useful for ligamentous injury assessment but less commonly required acutely.

Classification Systems

Current Gold Standard Treatment

Non-operative

• Indicated for stable elbows with minimal displacement and intact ulnohumeral articulation.
• Early controlled range of motion (ROM) within a protected arc (usually 30° to 130°) to prevent stiffness.
• Immobilization limited to short periods (<2 weeks) to avoid contracture.

Operative Indications and Treatment

• Ulnohumeral articulation disruption: Surgical restoration is mandatory to regain primary stability.
• Radial head fractures:
• Fixation preferred for reconstructible fractures (Mason II and some III).
• Radial head arthroplasty indicated for comminuted fractures not amenable to fixation.
• Resection only if MCL intact and no instability.
• Coronoid fractures: Fixation of fragments >50% or anteromedial facet fractures to restore anterior stability.
• Collateral ligament repair/reconstruction:
• Repair MCL and lateral collateral ligament complex in cases of instability or dislocation.
• Hinged external fixation: Used postoperatively to protect repairs, maintain ulnohumeral congruity, and allow early motion.

Modern Complications & Outcomes

Complications

Outcomes

• Early surgical intervention with restoration of bony and ligamentous anatomy yields the best functional outcomes.
• Hinged external fixation improves stability and allows early motion, reducing stiffness.
• Radial head arthroplasty has improved outcomes over resection in complex injuries with MCL disruption.
• Residual stiffness and mild instability may persist but are often functionally acceptable.

Classic Clinical Notes

Complex Instability of the Elbow

Reference: Morrey, Bernard F., AAOS Instructional Course Lectures, Volume 47, 1998

Main Message

• These are complex injuries. The basic principles are to first restore the ulnohumeral articulation (as this contributes most to elbow stability), then repair or replace the radial head as an important secondary stabilizer to the collateral ligaments. Finally, they protect the ulnohumeral articulation with an external fixator.

Points of Interest

Normal Stability

• The radial head can be resected in an otherwise uninjured elbow – IT IS A SECONDARY STABILIZER to the collateral ligaments. The resistance to valgus stress provided by the radial head is minimal when the MCL is intact, but when the MCL is torn, the radial head becomes important.
• The proximal ulna is the primary determinant of stability in the elbow.
• The coronoid is important, but it is not yet known how much must be present – probably at least 50% of it should be present.
• Ligaments provide 50% of the varus-valgus stability; the articular surfaces provide the rest; the anterior capsule is important in extension.

Radial Head Fracture with MCL Injury

• Rare, but should be recognized.
• Even though the MCL is the primary stabilizer and the radial head is the secondary stabilizer, the initial principle of management is to repair the radial head – either by osteosynthesis or prosthetic replacement. If the radiohumeral joint is not restored, then the MCL is fixed.

Radial Head Fracture with Elbow Dislocation (and intact ulna)

• “There is little information in the literature to help to define the optimum treatment of fracture dislocations.”
• “Stability” is defined as being stable in the arc of motion to within 45 to 50° of extension.
• Type I – posterior slab, then early ROM
• Type II – must treat the radial head, because the dislocation implies MCL injury
• Type III – excise, then direct repair of the collateral ligaments
• May consider a prosthesis, but should probably go ahead and fix the collaterals anyways. Consider using an external fixator to allow flexion yet maintain the ulnohumeral articulation.

Radial Head Fracture with Elbow Dislocation and Coronoid Fracture

• Fix or replace the radial head, then fix the coronoid, then protect it all with a hinged x-fix.

Thoughts

• Nice review. Morrey appears to use CADAVERIC replacement of the radial head. WEIRD. They are really big into the hinged x-fix to protect the stability of the joint and to protect any coronoid fixation.

Last Updated on January 25, 2026 by