Terrible Triad of Elbow

 Introduction  - 

Originally described in 1996 by Hotchkiss, the terrible triad of the elbow constitutes a highly unstable form of fracture-dislocation consisting of elbow dislocation with concomitant radial head or neck and coronoid process fractures. 

Relevant Anatomy

◎ Radial Head-

○ Resists posterolateral rotatory instability

○ Resists Valgus strain to the elbow

◎ Coronoid-

○ Forms the buttress for the ulno-humeral joint

○ Prevents posterior subluxation with elbow from full flexion to 30 degree 

◎ Medial collateral ligament

* Anterior bundle

      - most important for stability, 

      - restraint to valgus and posteromedial rotatory instability 

      - insertion on sublime tubercle (anteromedial facet of coronoid)

* Posterior bundle 

* Transverse ligament

◎ Lateral collateral ligament

       - Insertion on supinator crest distal to lesser sigmoid notch 

      - the primary restraint to posterolateral rotatory instability 

      - Avulsion from lateral condyle when injured 

- Components

               Lateral ulnar collateral ligament (most important for stability) 

               Radial collateral ligament 

               Annular ligament 

              Accessory ligament 

Mechanism and Presentation

◎ Fall on outstretched hand that is in mild flexion 

◎ Valgus stress at elbow 

◎ Forearm supination

*  Evaluation in ED - 

○ X-rays 

○ NV status 

○ Elbow reduction in ED 

○ Appropriate immobilisation in above elbow back slab 

○ Confirm NV status again 

○ Repeat X-rays 

○ Check for distal radio-ulnar joint injury (Essex Lopresti injury)

○ CT scan thereafter (can happen from the ward/ED)

Radiographs and definition

◎ Damage/Fracture to radial head       

◎ Damage/Fracture to coronoid 

◎ Elbow dislocation

◎ Get pre and post reduction x-rays 

◎ Forearm and wrist x-rays - if distal radioulnar joint injury is suspected

Typical images of a reduced elbow with Terrible Triad injury - 

Treatment (conservative)

• Indication -

•  Ulno-humeral and radio-capitellar joints well reduced 
•  Radial head # must not meet surgical indications 
• Small coronoid (mayo type 1) # 
• elbow should be sufficiently stable to allow early ROM

Protocol- 

• 1 week of immobilization (at 90 degree) 

• Active assisted motion initiated with the splint on. 

• ROM from full flexion to progressive extension. Full extension is done around 6-week time. 

• Strengthening after 6 weeks

Radial Head Surgical indications

Mason classification  

◎ Mason Type II with mechanical block

◎ Mason Type III where ORIF feasible

◎ Presence of other complex ipsilateral elbow injuries

Coronoid fracture 

◎ Transverse fractures (Mayo type I) 

◎ Anteromedial facet fractures (Mayo type II) 

◎ Basilar fractures (Mayo type III)

Management (Surgical)

◎ Indication - Terrible triad injury with

• unstable radial head fracture (meeting surgical indications)  
• type II/III coronoid fracture
• Posterior skin incision advantageous
• Radial head- 

              ○ Radial head ORIF indicated in constructible fractures 

              ○ Radial head arthroplasty/excision in severely comminuted # radial head

• Coronoid-

             ○Can be fixed through radial head defect laterally 

             ○ FCU split approach for isolated coronoid # 

             ○ Mayo type 1- suture anchor/suture tunnel in unstable elbow 

            ○ Mayo type 2- suture / buttress plate in larger fragment 

            ○ Mayo type 3- Lag screw +/- buttress plate

• LCL repair 

         ○ usually avulsed from origin on lateral epicondyle 

         ○ reattach with suture anchors or trans-osseous sutures 

         ○ if MCL is intact, LCL is repaired with forearm in pronation 

         ○ if MCL injured, LCL is repaired with forearm in supination to avoid medial gapping 

        ○ repairs are performed with elbow at 90 degrees of flexion

• MCL repair

       ○ Indicated if instability on examination after LCL and fracture fixation,  Especially with extension beyond 30 degrees

       ○ Persistent posteromedial instability following radial head replacement/repair and LCL repair in the setting of Type I/II coronoid fracture should be managed with MCL repair

• Hinged fixators- when instability is noted after complete bone and soft tissue repair

Post Operative

• Immobilize in flexion with forearm pronation to provide stability against posterior

subluxation

• If both MCL and LCL were repaired, elbow in flexion and forearm neutral rotation

• Active ROM exercises 48 hours after surgery 

Complications

• Instability- more common following type I or II coronoid fractures 

• Failure of internal fixation- more common following repair of radial neck fractures

           - poor vascularity leading to osteonecrosis and non-union

• Post-traumatic stiffness 

• Heterotopic ossification

          - prophylaxis in pts with head injury or in setting of revision surgery

• Post-traumatic arthritis

References -

  - Ring D, Jupiter JB, Zilberfarb J. "Terrible Triad Injuries of the Elbow." *J Orthop Trauma.* 2024.  

  - O’Driscoll SW. "Posterolateral Rotatory Instability of the Elbow." *J Hand Surg.* 2023.  

Thank You