The term "Terrible Triad of the Elbow" was first proposed by Hotchkiss in 1996, referring to an elbow dislocation combined with fractures of the radial head and the coronoid process of the ulna; surgical intervention is often required. Pugh et al. achieved favorable clinical outcomes using a standardized surgical protocol for treating the terrible triad. This protocol includes: fixation or replacement of the radial head, fixation of the coronoid fracture, and repair of the lateral collateral ligament (LCL). If elbow instability persists post-treatment, exploration and repair of the medial collateral ligament (MCL) are performed. Should instability remain after this secondary intervention, application of a hinged external fixator is considered.
01 Classification and Surgical Treatment Methods
The Terrible Triad of the Elbow involves fractures of the radial head and coronoid process concurrent with elbow dislocation. While radial head and coronoid fractures have their own independent classification systems, in this complex injury pattern, the separate classifications can lead to conflicting treatment choices. For example, under the isolated Mason classification, Type II radial head fractures often do not require surgery. However, in the terrible triad complex, aggressive surgical fixation and reconstruction of the radial head, along with repair of LCL injury, are necessary.
Given this, it is essential to consider the elbow as a functional unit. Based on the severity and extent of the radial head fracture, the size and location of the coronoid fracture, and the integrity of the MCL, a unique classification system for the Terrible Triad of the Elbow is proposed.
Commencing in March 2009, patients with this injury were treated according to this classification system. This study retrospectively analyzes a cohort of patients with the objectives to:
① Propose a classification system for the Terrible Triad of the Elbow;
② Report the surgical approach selection strategy based on this classification system;
③ Evaluate the clinical efficacy of applying this classification system.
02 Materials and Methods
1. Inclusion and Exclusion Criteria
· Inclusion Criteria: ① Closed injury; ② Diagnosis of Terrible Triad of the Elbow; ③ Treated surgically; ④ Minimum follow-up period of 24 months with complete follow-up data.
· Exclusion Criteria: ① Open injury; ② Associated nerve injury; ③ Follow-up period < 24 months or incomplete clinical data.
2. Classification and Treatment Strategy
Based on the injury status of the radial head, coronoid process, and medial collateral ligament (MCL), the Terrible Triad of the Elbow is classified into Types: IA, IB, II, III, and IV.
(I) Type I Injury
Radial head fracture involving ≤ 40% of the radial head, combined with a coronoid tip fracture. This type is further subdivided into two subtypes based on the size of the coronoid tip fracture fragment.
· Type IA: Coronoid tip fracture fragment ≤ 2 mm, corresponding to O'Driscoll subtype 1 tip fracture. In most cases, the radial head remains largely intact and the coronoid fragment is small, requiring no additional incision for coronoid fixation. Therefore, for Type IA injuries in this cohort, only radial head fixation and LCL repair were performed, without coronoid fracture fixation.
· Type IB: Coronoid tip fracture fragment > 2 mm, corresponding to O'Driscoll subtype 2 tip fracture. (Translation continues based on the original text structure)
(II) Type II Injury
Comminuted and/or displaced radial head fractures involving >40% of the radial head, accompanied by a tip fracture of the coronoid process consistent with the O'Driscoll coronoid fracture classification. Since the majority of the radial head is fractured and the coronoid fracture involves the tip near the radial notch, the coronoid fracture can be fixed through a lateral approach. For this group of Type II injuries, a single lateral approach is used to perform either radial head replacement or fixation, along with fixation of the coronoid fracture and repair of the lateral collateral ligament (LCL).
(III) Type III Injury
This type involves an anteromedial coronoid fracture, consistent with the anteromedial facet fracture or base fracture in the O'Driscoll coronoid fracture classification. Fixation of the anteromedial coronoid fracture is generally difficult to achieve through a lateral approach. Even after radial head resection during replacement, reduction and fixation of the anteromedial coronoid fracture remain challenging via the lateral approach. Therefore, an anteromedial approach can be utilized to address the coronoid fracture. For Type III injuries, a lateral approach is used to fix or replace the radial head and repair the LCL, while an anteromedial approach is employed to fix the coronoid fracture.
(IV) Type IV Injury
This encompasses elbow dislocation, radial head fracture, coronoid fracture, concomitant with medial collateral ligament (MCL) injury (Table 1). We utilize a combined approach to repair the MCL.
3.Surgical Technique
(I) Anesthesia and Positioning
Brachial plexus anesthesia was administered. The patient was placed in the supine position with the affected upper limb abducted and positioned on a separate, sterile side table. A sterile tourniquet was applied.
(II) Incision and Exposure
1. Type IA Injury: A lateral Kocher approach was used to expose and fixate the radial head and repair the lateral collateral ligament (LCL). The coronoid fracture was not fixed.
2. Type IB Injury: The lateral Kocher approach was used to repair the radial head and LCL. An anteromedial "over-the-top" approach was used to fixate the coronoid fracture.
3. Type II Injury: A lateral splitting approach through the common extensor tendon origin was used for radial head replacement or fixation, combined with fixation of the coronoid fracture and repair of the LCL.
4. Type III Injury: The lateral Kocher approach was used to fixate or replace the radial head and repair the LCL. The anteromedial "over-the-top" approach was used to fixate the coronoid fracture.
5. Type IV Injury: Involves concomitant medial collateral ligament (MCL) injury. A combined approach strategy was employed: the anteromedial "over-the-top" approach was used to repair the MCL. Isolated lateral approaches were used for Type IA and II injuries. Combined lateral and anteromedial approaches were used for Type IB, III, and IV injuries. Lateral Approach Note: For Type II injuries, the lateral splitting approach of the common extensor tendon was selected instead of the Kocher approach to facilitate exposure of the coronoid fracture through the lateral incision.
The three injured structures – coronoid fracture, radial head fracture, and lateral collateral ligament – were repaired sequentially from deep to superficial. For other injury types (IA, IB, III, IV), the lateral Kocher approach was chosen for radial head fixation or replacement. Anteromedial Approach: The "over-the-top" approach was used to expose the coronoid fracture.
(III) Reduction, Fixation, and Ligament Repair/Reconstruction
Radial head fractures were fixated using countersink screws or in combination with mini-plates. For radial head fractures with bone defects after reduction (7 cases in this series), autologous bone grafting was performed using bone harvested from the lateral humeral condylar metaphysis. Small fragments were occasionally fixated with Kirschner wires (K-wires) if necessary, but their use was minimized to avoid potential postoperative migration. If the radial head was deemed irreparable, prosthetic replacement was performed.
The fixation method for coronoid fractures was selected based on fragment size and location. Tip fractures were typically managed with flexible fixation techniques such as suture anchors and suture lasso techniques. However, coronoid fractures were not addressed in Type IA injuries in this series. Larger fragments were fixated using 2.7-mm diameter cannulated screws or in combination with T-shaped mini-locking plates. Larger anteromedial coronoid fragments were best fixated via the anteromedial approach using buttress plate and screws.
Joint stability was assessed: concentric reduction indicated stability. If posterior or posterolateral instability was present, the fixation of the radial head and coronoid was meticulously checked, and consideration was given to augmenting the LCL repair.
If the aforementioned repairs and fixations were deemed stable, further exposure and repair of the medial ligament complex were undertaken. For patients undergoing coronoid fixation via the anteromedial approach, the MCL, particularly the integrity of the anterior bundle, could be explored and repaired through the same incision if torn.
All 7 patients with MCL injury in this series underwent repair using suture anchors. Ligament tears were identified and repaired concurrently during anteromedial approach coronoid fixation in 5 cases. In the remaining 2 cases, tears were identified during exploration prompted by positive Hanging arm and valgus stress tests and subsequently repaired. If instability persisted after MCL repair, application of an adjustable elbow external fixator was considered.
(IV) Wound Closure
The tourniquet was released, hemostasis was meticulously achieved, and the wound was closed in layers routinely. A negative-pressure drainage tube was placed, and the wound was dressed with sterile gauze.
03 Discussion
Complex elbow fracture-dislocations primarily include the terrible triad of the elbow, transolecranon fracture-dislocations, and Monteggia fractures in adults. Since the terrible triad injury involves the radial head, coronoid process, elbow joint capsule, and ligaments – excluding the olecranon and distal humerus – the classification system in this study was based on the injury patterns of the radial head, coronoid process, and ligaments. Furthermore, as the lateral collateral ligament (LCL) is invariably injured in elbow dislocations, LCL injury was not included as a separate criterion within this classification system.
This classification system is primarily based on:
1. The severity of the radial head fracture injury. This primarily serves as a reference for whether a coronoid tip fracture can be addressed via the lateral approach.
2. The location and extent of the coronoid fracture. This serves as the basis for managing the coronoid fracture and determines the necessity of an additional anteromedial approach.
3. The presence or absence of medial collateral ligament (MCL) injury. This constitutes an independent classification tier, impacting intraoperative and postoperative management strategies.
4. The reliability analysis results for this classification system indicate it is fundamentally credible and demonstrates good consistency.
04 ATOM Medical Elbow Joint Treatment Protocol
Product Features:
1. Anatomically designed for the Asian population;
2. Smaller head diameter reduces bone removal, allowing placement of more screws in confined spaces;
3. Three head screws inserted from medial to lateral into the humeral trochlea;
4. Enhanced fixation stability;
5. Low-profile head design minimizes soft tissue irritation.
