Why Neglected Elbow Dislocation with MCL + Annular Ligament Repair (but NO LCL Repair) Still Results in Posterolateral Instability

Understanding the Anatomy of the "Circle of Horii" (O'Driscoll's Sequential Disruption Model)

The Core Paradox: Why Does Posterolateral Instability Persist Despite MCL + Annular Ligament Repair?

1. LUCL is the primary restraint to PLRI: The lateral ulnar collateral ligament (LUCL) runs from the lateral epicondyle to the supinator crest of the ulna. It prevents the ulna from rotating posterolaterally away from the humerus during supination/extension loading. Without it, the joint pivots posterolaterally regardless of other repairs.
2. MCL is a valgus stabilizer, not a PLRI stabilizer: The MCL (anterior bundle) primarily resists valgus stress and is the primary stabilizer of the medial side. Repairing it restores medial-sided valgus stability but does nothing to prevent posterolateral rotatory subluxation.
3. Annular ligament stabilizes the radial head around the ulna (radioulnar joint), not the ulnohumeral joint in the rotatory plane. Its repair prevents radial head instability but does not prevent the whole forearm unit from rotating posterolaterally off the humerus.
4. Without the LUCL: Even with a perfectly repaired MCL, when the patient extends and supinates the elbow under load, the ulna + radius rotate as a unit posterolaterally on the humerus — this is the classic posterolateral rotatory instability (PLRI) pattern. The lateral pivot-shift test of the elbow (O'Driscoll's test) will remain positive.

Clinical Implication: Sequence of Surgical Repair

"Repair the LCL first; test stability. If still unstable, then repair the MCL. MCL repair is often unnecessary if LCL is adequately repaired."

• ✅ Restored medial valgus stability
• ✅ Restored proximal radioulnar congruency
• ❌ Left the PRIMARY PLRI restraint (LUCL) non-functional

Summary Table

In Summary

• The LUCL is the anatomic sling that tethers the ulna to the lateral epicondyle during supination/extension loading.
• No amount of medial-side repair compensates for a deficient lateral pivot stabilizer.
• In chronic/neglected cases, LCL reconstruction (not just repair) with a tendon graft is often required because the ligament tissue has degenerated and is not reparable.

Why the LCL Was NOT Repaired in Neglected Elbow Dislocation

1. The LCL Is No Longer Identifiable — Absorbed into Scar Tissue

"The common extensor complex had been avulsed from its insertion site on the lateral epicondyle. The radial head was buttonholed through the lateral soft tissues, and there was no lateral ligamentous complex identifiable. Abundant hypertrophic scar tissue surrounded the radial head."

• Retracts, scars down, and becomes indistinguishable from surrounding fibrotic tissue
• The tissue is no longer robust enough to hold sutures (poor tissue quality)
• There is no discrete ligament "end" to reattach

2. Tissue Degeneration Makes Primary Repair Impossible

• Myxoid degeneration — the collagen fibres lose their organized structure
• Fibrotic contracture — the ligament shrinks and loses length, making re-approximation to the anatomical footprint impossible
• Loss of mechanical integrity — even if visible, the tissue cannot hold sutures and would fail immediately under load

3. The Lateral Side Is Buried in Dense Periarticular Fibrosis

• Periarticular heterotopic ossification (HO) precursors
• Dense fibrous adhesions between radial head, capitellum, and lateral soft tissues
• The radial head often "buttonholes" through the lateral capsule

4. Surgical Strategy: Staged or Priority-Based Repair

5. Assumption That MCL Repair Alone Would Suffice

• Restoring medial stability + joint reduction would allow secondary LCL healing
• The annular ligament repair would adequately stabilize the lateral side

Bottom Line

Can K-Wire + MCL + Annular Ligament Repair Achieve Adequate Stability Without LCL Reconstruction in a 70-Year-Old?

Short answer: Yes — with important caveats — and in fact, for a 70-year-old, this may be the most appropriate approach, but the K-wire is doing the heavy lifting.

What the K-Wire Actually Does Here

• Mechanically hold the reduced ulnohumeral joint concentric while the repaired soft tissues (MCL, annular ligament, and whatever LCL remnant exists) heal
• Substitute for the missing LUCL during the early healing phase by preventing posterolateral rotation
• Allow the soft tissue envelope to consolidate around the reduced joint before the pin is removed (typically at 3–6 weeks)

Why This Is a Reasonable Strategy in a 70-Year-Old Specifically

The Evidence: K-Wire Alone as a Stabilizer

Open reduction + fibrous tissue removal + K-wire fixation ± triceps lengthening (without formal LCL reconstruction)

What Stability Is Being Achieved

Limitations / What Can Still Go Wrong

1. PLRI may persist after K-wire removal if LCL healing is inadequate — the elbow may feel unstable in extension/supination under load
2. K-wire complications: pin track infection, pin migration, breakage, need for removal under anaesthesia
3. Stiffness is the most common complication — the immobilization required for K-wire healing directly causes flexion contracture. In an elderly patient, this may be more disabling than the original instability
4. Redislocation after K-wire removal if soft tissue healing is suboptimal

The Surgical Hierarchy for a 70-Year-Old With Neglected Elbow Dislocation

Age > 65 yrs + neglected dislocation
         │
         ├── Significant arthritic change present?
         │         └── YES → Total Elbow Arthroplasty (gold standard)
         │
         └── No/mild arthritis + reasonable bone stock?
                   └── Open reduction + K-wire + soft tissue repair
                             (MCL + annular ± LCL remnant repair)
                             ↓
                   K-wire in for 3–6 weeks → Early protected ROM
                             ↓
                   Accept fibrous stability as endpoint
                   Formal LCL reconstruction NOT required

Bottom Line

1. The K-wire holds the joint reduced while the soft tissue heals
2. Periarticular fibrosis provides secondary stability
3. Functional demands are low — ADL-level stability, not sport-level stability
4. Formal LCL reconstruction carries higher surgical risk and may fail in elderly bone anyway
5. TEA remains the preferred definitive option if this fails or if arthritis is present