Restoration of the coronoid buttress for elbow stability | advanced
Surgical Imaging
The trap: Dismissing a displaced anteromedial facet fragment as 'small' or 'not worth fixing' because the radial head has already been addressed — the anteromedial facet is the primary restraint to varus and posteromedial rotation once the lateral collateral ligament is repaired.
The fix: Any anteromedial facet fracture with greater than 2 mm displacement or involving greater than 50 percent of facet width requires anatomic reduction and buttress plating. Failure to restore this buttress produces chronic posteromedial subluxation, capitellar erosion, and early arthrosis.
Location: The ulnar nerve lies in the cubital tunnel posterior to the medial epicondyle — it is at risk during the Hotchkiss approach when the flexor-pronator mass is elevated or when a buttress plate is applied to the anteromedial facet.
Risk: Direct injury during dissection, compression by retractors, or late irritation by hardware. Always identify the nerve proximally at the medial epicondyle, decompress the cubital tunnel, and transpose anteriorly if the plate sits against the nerve bed.
Location: The anterior band of the medial collateral ligament inserts on the sublime tubercle just distal and slightly posterior to the anteromedial facet — aggressive retraction or plate placement can avulse or compress this critical restraint.
Risk: Iatrogenic valgus instability created while attempting to fix the coronoid. The Hotchkiss interval is designed to stay anterior to the MCL insertion — identify the sublime tubercle and keep all dissection and hardware anterior to it.
The trap: Leaving a small coronoid tip fragment unreduced because 'it is too small to fix' — the tip carries the anterior capsule insertion that acts as a checkrein against posterior translation.
The fix: Even tip fragments greater than 5 mm should be captured with a suture lasso through the anterior capsule and tied over the ulna. This restores the capsular restraint and prevents recurrent posterior subluxation after terrible triad reconstruction.
The trap: Focusing solely on the coronoid while the radial head remains unreduced or inadequately fixed — the radial head is the secondary stabilizer once the coronoid buttress is lost.
The fix: In terrible triad injuries, restore the radial head (ORIF or replacement) BEFORE final coronoid fixation. A stable radial head provides the lateral column against which the coronoid reduction can be judged under fluoroscopy.
The trap: Allowing early aggressive motion beyond the stable arc identified intraoperatively — this produces recurrent subluxation, capitellar erosion, and heterotopic ossification.
The fix: Confirm a concentric arc from at least 20 degrees extension to 130 degrees flexion under fluoroscopy with the lateral collateral ligament repaired. Begin protected motion within this arc immediately; delay terminal extension until 4-6 weeks if the arc was marginal.
C.O.R.O.N.O.I.D.CORONOID — O'Driscoll Classification and Fixation Priorities
H.O.T.C.H.K.I.S.S.HOTCHKISS — Medial Approach for Anteromedial Facet
S.T.A.B.I.L.I.T.Y.STABILITY — Intraoperative Confirmation of Elbow Stability
Surgical Indications
Absolute Indications
- Displaced anteromedial facet fracture greater than 2 mm with varus posteromedial rotatory instability on stress fluoroscopy
- Basal coronoid fracture (Regan-Morrey Type III or O'Driscoll basal subtype) with elbow instability after radial head fixation
- Terrible triad injury with coronoid fracture and persistent posterior or posteromedial subluxation after radial head and lateral collateral ligament reconstruction
- Isolated coronoid fracture with greater than 50 percent involvement and mechanical block to motion
Relative Indications
- Tip fragment greater than 5 mm in a young active patient after elbow dislocation
- Anteromedial facet fracture between 1-2 mm displacement with borderline varus stress stability
- Patient preference for definitive fixation over non-operative management in borderline cases
Contraindications
Absolute:
- Active elbow infection or open fracture with gross contamination
- Severe osteoporosis precluding stable fixation
- Patient medically unfit for surgery
Relative:
- Minimally displaced tip fragment less than 5 mm in low-demand elderly patient
- Chronic malunited coronoid fracture with established arthrosis (consider arthroscopic debridement or arthroplasty instead)
Evidence for Coronoid Fixation
Why Small Fragments Matter
- The coronoid tip carries the anterior capsule insertion — loss of this restraint allows posterior translation even after radial head replacement and lateral collateral repair
- Cadaveric sectioning studies demonstrate that removal of the coronoid tip alone produces measurable posterior subluxation at 30-40 degrees flexion
- Clinical series show that unreduced tip fragments greater than 5 mm are associated with higher rates of recurrent instability and early arthrosis after terrible triad reconstruction
Anteromedial Facet and VPMRI
- The anteromedial facet is the primary bony restraint to varus and posteromedial rotation once the lateral collateral ligament is intact
- Fractures involving greater than 50 percent of the anteromedial facet width or with greater than 2 mm displacement produce clinically significant varus posteromedial rotatory instability
- Buttress plating restores the facet and prevents chronic subluxation, capitellar erosion, and ulnohumeral arthrosis
Fixation Technique Outcomes
- Suture lasso technique for tip fragments achieves stable fixation with low complication rates when combined with lateral collateral ligament repair
- Buttress plating of the anteromedial facet provides rigid fixation allowing early motion and has shown good to excellent outcomes in multiple series
- Combined medial and lateral approaches in terrible triad injuries yield stable concentric elbows in greater than 85 percent of cases when the coronoid buttress is restored
Fixation Options — Fragment Size and Location
Key Evidence
Posterior dislocation of the elbow with fractures of the radial head and coronoid
Fixation of the coronoid process in elbow fracture-dislocations
The 'terrible triad' of the elbow
Difficult elbow fractures: pearls and pitfalls
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 34-year-old man sustains a terrible triad injury of the elbow after a fall from height. Radiographs show a displaced Regan-Morrey Type II coronoid fracture, a comminuted radial head fracture, and posterolateral elbow dislocation. After closed reduction, CT confirms an O'Driscoll anteromedial facet subtype fracture with 3 mm displacement. How do you plan the surgical reconstruction?”
“You have performed suture lasso fixation of a small coronoid tip fragment through a lateral approach as part of a terrible triad reconstruction. On-table fluoroscopy shows concentric reduction, but at the 2-week review the lateral radiograph demonstrates subtle posterior subluxation of the ulnohumeral joint. What has gone wrong and how do you manage it?”
“A 42-year-old woman undergoes Hotchkiss medial approach and buttress plate fixation of a displaced anteromedial facet coronoid fracture. At 3 months she has a stable concentric elbow with 20 degrees extension to 130 degrees flexion, but complains of numbness and tingling in the ulnar two digits with positive Tinel sign at the transposition site. How do you manage the ulnar nerve complication?”