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Radial Collateral Ligament of the Thumb Injury

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Other Names

  • RCL Thumb Injury
  • Thumb RCL


  • This page refers to injuries to the RCL of the thumb


  • Overall less common than UCL injuries
  • Important to consider in unstable MCP injuries


  • Most often found in active populations
  • Implicated in 25% of NFL thumb injuries
  • Implicated in 32% of unstable MCP injuries


Anatomy of the Radial Collateral Ligament


  • Mechanism: usually forced adduction of the thumb
  • Injury patterns:
    • Proper Collateral Ligament most common cause of clinically significant injury
    • Proximal avulsion 55%, distal avulsion 29%, midsubstance tear 16% [7]

Anatomy of the Radial Collateral Ligament of the thumb

  • RCL divided into:
    • Proper Collateral Ligament: provides stability in flexion
    • Accessory Collateral Ligament: provides stability in extension
  • Spans from dorsal lateral metacarpal to lateral proximal phalanx

Risk Factors

  • Active populations (athletes, military)

Differential Diagnosis

Differential Diagnosis Finger And Hand Pain

Clinical Features


  • Typically forced MCP adduction
  • Sometimes axial load injury
  • Pain and difficulty with pinch

Physical Exam: Physical Examination Hand

  • Ecchymosis and tenderness of the radial MCP
  • Radial MCP laxity (must test at 0 and 30 degrees flexion), evaluate for endpoint

Special Tests

  • Key pinch grip (thumb to radial index finger)


Radiograph of an RCL tear


  • Evaluate for avulsion fractures and volar or ulnar subluxation
  • Stress views showing >30 degrees angulation suggest complete rupture


  • Not shown to be beneficial over physical exam


  • Can be used in the setting of inconclusive exam


  • The classification of MCP collateral ligament injuries is critical to the guidance of proper management. RCL and UCL injuries utilize the same three stage classification system as follows {1-4}:
    • Grade 1: Incomplete tear of the RCL with only few torn fibers – tenderness to palpation and without laxity present on stressing examination
    • Grade 2: Incomplete tear of the RCL with a greater number of torn fibers present – increased tenderness to palpation at the radial aspect of the MCP, more prominent swelling and the presence of laxity on stressing but with a definitive end point.
    • Grade 3: Complete tear of the RCL – tenderness to palpation, swelling and prominent instability/laxity with no end point on stressing examination



  • Grade 1 and 2: thumb spica splint or thumb spica cast for 4-6 weeks
  • Grade 3: can consider thumb spica in nonathletes
    • With <30 degrees angulation and <3mm subluxation on XR


  • Indications
    • Grade 3 injury in athletes
    • >30 degrees angulation on stress XR
    • >3mm subluxation on XR
  • Thumb spica cast for 6 weeks post-op

Rehab and Return to Play


  • Use thumb spica brace if still symptomatic after 4-6 weeks casting
  • ROM and strengthening exercises when pain resolves for nonoperative management
  • Early ROM after 6 weeks casting for operative management, then begin strengthening exercises at 3 months

Return to Play

  • Nonoperative: when pain has resolved with strength and ROM exercises
  • Operative: after completion of strengthening and ROM program, at least 3 months post-op

Prognosis and Complications


  • Grade 1 and 2 typically heal within 4-6 weeks
  • Grade 3 may develop chronic instability if not surgically repaired


  • Grade 3 injuries may develop chronic instability or subluxation
  • May develop MCP osteoarthritis

See Also




  1. LM;, Rozmaryn. “The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment.” The Journal of Hand Surgery, U.S. National Library of Medicine, 2017, pubmed.ncbi.nlm.nih.gov/29101974/.
  2. Netscher, David T, et al. “Finger Injuries in Ball Sports.” Hand Clinics, U.S. National Library of Medicine, Feb. 2017, www.ncbi.nlm.nih.gov/pubmed/27886829.
  3. RG;, Daley D;Geary M;Gaston. “Thumb Metacarpophalangeal Ulnar and Radial Collateral Ligament Injuries.” Clinics in Sports Medicine, U.S. National Library of Medicine, 2020, pubmed.ncbi.nlm.nih.gov/32115093/.
  4. SK;, Edelstein DM;Kardashian G;Lee. “Radial Collateral Ligament Injuries of the Thumb.” The Journal of Hand Surgery, U.S. National Library of Medicine, 2008, pubmed.ncbi.nlm.nih.gov/18590860/.
  5. Mitchell TW, Mitchell SA, Wu C. Radial Collateral Ligament Injuries of the Thumb Metacarpophalangeal Joint. Curr Rev Musculoskelet Med. 2022 Dec;15(6):581-589. doi: 10.1007/s12178-022-09805-z. Epub 2022 Oct 28. PMID: 36303098; PMCID: PMC9789250.
  6. Gluck JS, Balutis EC, Glickel SZ. "Thumb Ligament Injuries." The Journal of Hand Surgery, Volume 40, Issue 4, 2015, Pages 835-842, ISSN 0363-5023, https://doi.org/10.1016/j.jhsa.2014.11.009.
  7. Coyle MP., Jr Grade III radial collateral ligament injuries of the thumb metacarpophalangeal joint: treatment by soft tissue advancement and bony reattachment. J Hand Surg Am. 2003;28(1):14–20. doi: 10.1053/jhsu.2003.50008.
Created by:
John Kiel on 9 August 2020 15:22:06
Last edited:
27 October 2023 17:22:43