Illustration of a locked finger joint being unlocked.

Unlocking Fingers: Understanding and Treating Metacarpophalangeal Joint Locking

Avery Sinclair in Health & Wellness August 2025 • 4 min read.

"A comprehensive guide to the causes, diagnosis, and treatment options for locked MCP joints, including a rare case of bilateral occurrence."

Metacarpophalangeal (MCP) joint locking, a condition where a finger becomes stuck in a bent position, can significantly impact daily life. While not always common, understanding the causes and treatments is crucial for those affected. This article aims to shed light on this condition, offering insights into its diagnosis and management.

Often misdiagnosed as trigger finger, MCP joint locking requires a nuanced understanding. The key difference lies in the mobility of the proximal interphalangeal joint, which remains unaffected in MCP joint locking. This article will guide you through differentiating between these conditions and recognizing the specific characteristics of MCP joint locking.

Drawing from a case report and a systematic literature review, we'll explore the various factors contributing to MCP joint locking, including a rare instance of bilateral occurrence. We'll delve into treatment options, from manual reduction to surgical interventions, providing a comprehensive overview for both patients and healthcare professionals.

What Causes Metacarpophalangeal (MCP) Joint Locking?

Illustration of a locked finger joint being unlocked.

MCP joint locking arises from a variety of factors, often involving the structures surrounding the joint. These can range from bony overgrowths to soft tissue abnormalities that impede normal finger movement. Understanding these underlying causes is vital for effective treatment.

Several mechanisms can lead to this condition. These include:

Collateral ligament issues: The collateral ligaments, particularly the radial accessory collateral ligament (ACL), can become caught on bony prominences or osteophytes on the metacarpal head.
Soft tissue abnormalities: Tears in the palmar plate, enlarged sesamoids, or entrapment of tendons can also cause locking.
Bony abnormalities: An abnormal shape of the metacarpal head or the presence of osteophytes can physically block the joint's movement.
Trauma and Overuse: While less common, injuries or repetitive stress can contribute to the development of MCP joint locking.

Notably, a study highlighted a case of bilateral MCP joint locking, where both hands were affected due to radial side prominence of the metacarpal head. This rare occurrence underscores the importance of considering anatomical variations and predisposing factors in diagnosis and treatment.

Navigating Treatment Options and Recovery

The approach to treating locked MCP joints varies depending on the underlying cause and severity of the condition. In some cases, gentle closed reduction, a manual manipulation technique, may be sufficient to unlock the joint. However, surgical intervention is often necessary to address structural issues or remove obstructions.

Surgical procedures typically involve releasing or repairing the affected ligaments, removing bony prominences, or addressing any other anatomical abnormalities contributing to the locking. The specific surgical approach will depend on the individual case and the surgeon's assessment.

With appropriate treatment, most patients can regain full range of motion and function in their affected finger. Early diagnosis and intervention are key to preventing long-term complications such as flexion contractures and limitations in daily activities. If you suspect you have a locked MCP joint, seeking prompt medical evaluation is essential for optimal outcomes.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1097/sap.0000000000001593, Alternate LINK

Title: Bilateral Locking Of The Metacarpophalangeal Joint

Subject: Surgery

Journal: Annals of Plastic Surgery

Publisher: Ovid Technologies (Wolters Kluwer Health)

Authors: Keshav Poonit, Bin Zhao, Zeyuan Jin, Kaizong Yuan, Tokai B. Cooper, Hede Yan

Published: 2018-11-01

Everything You Need To Know

What are the main causes of Metacarpophalangeal (MCP) joint locking?

Metacarpophalangeal (MCP) joint locking occurs due to several factors affecting the joint's structure. These include collateral ligament issues, such as the radial accessory collateral ligament (ACL) getting caught on bony prominences. Soft tissue abnormalities like tears in the palmar plate or enlarged sesamoids can also cause locking. Additionally, bony abnormalities, such as osteophytes on the metacarpal head, and trauma or overuse may contribute to this condition.

How is Metacarpophalangeal (MCP) joint locking different from trigger finger?

MCP joint locking is often confused with trigger finger, but they are distinct conditions. The primary difference lies in the proximal interphalangeal joint mobility. In MCP joint locking, this joint remains unaffected, whereas trigger finger typically involves issues with tendon gliding affecting finger flexion and extension. A correct diagnosis is essential for effective treatment.

What are the treatment options for a locked Metacarpophalangeal (MCP) joint?

Treatment for locked MCP joints ranges from manual reduction to surgical interventions, depending on the cause and severity. Gentle closed reduction, a manual manipulation technique, may unlock the joint in some cases. However, surgical intervention is often necessary to address structural issues like bony overgrowths or soft tissue entrapments that impede normal finger movement. The specific approach is tailored to the individual's condition.

What does it mean if someone experiences bilateral Metacarpophalangeal (MCP) joint locking?

Bilateral MCP joint locking, where both hands are affected simultaneously, is rare but can occur. It often involves anatomical variations or predisposing factors, such as radial side prominence of the metacarpal head. Such cases underscore the importance of considering individual anatomical differences when diagnosing and treating MCP joint locking, as the underlying cause may be related to unique structural features.

What role does the radial accessory collateral ligament (ACL) play in Metacarpophalangeal (MCP) joint locking?

The radial accessory collateral ligament (ACL) plays a crucial role in MCP joint locking when it becomes impinged on bony prominences or osteophytes of the metacarpal head. This impingement restricts the normal range of motion, leading to the finger becoming stuck in a bent position. Understanding the interaction between the radial ACL and the metacarpal head is vital for both diagnosis, especially in cases where bony abnormalities are present.