Distal Humerus Fractures

Distal humerus fractures make up 2-6% of all fractures and a significant proportion of elbow fractures, and about 30% of them are intra-articular. The Edinburgh series (Robinson) puts the adult incidence at 5.7 per 100,000 per year, with a bimodal age distribution and a near-equal male-to-female ratio overall. They are difficult injuries: the anatomy is complex, it has to be reconstructed, and the result depends on meticulous surgical technique.

Who. The two peaks are different patients. Young males aged 20-40 break the distal humerus in high-energy trauma (road traffic accidents, falls from height, sport). Elderly females aged 65 and over break it in a low-energy fall onto osteoporotic bone.

Mechanism. A fall directly onto the elbow is the most common. The others:

• Fall on the outstretched hand with the elbow flexed
• High-energy direct trauma
• Sports injuries (football, rugby)

The osteoporotic elbow. Achieving stable fixation in osteoporotic bone is challenging. The old "bag of bones" approach of leaving these fractures alone has largely been replaced by ORIF or primary total elbow arthroplasty, which give better functional outcomes; the place it still has is set out under Management.

The two columns. The distal humerus is an inverted triangle. The medial column supports the medial trochlear ridge, the lateral column supports the capitellum and the lateral trochlea, the apex is where the columns meet at the metaphysis, and the base is the articular surface of trochlea and capitellum. The columns form a triangular arch that carries the joint, and surgical reconstruction has to restore that arch: both columns must be independently fixed to the shaft for the elbow to be stable.

The joint. The trochlea is spool-shaped and articulates with the ulna; the capitellum is hemispherical and articulates with the radial head. In front, the coronoid fossa accepts the coronoid in flexion; behind, the olecranon fossa accepts the olecranon in extension. The bone between the two fossae is very thin.

Normal angles.

• Carrying angle: 10-15 degrees of valgus with the arm extended and the palm forward
• Baumann angle: mean about 71 degrees, but the normal range in healthy children is wide (54-90 degrees, PMID 42024825); it is a comparison against the uninjured elbow, not a threshold
• Anterior humeral line: passes through the middle third of the capitellum

The nerves and the artery. The radial nerve travels in the spiral groove and passes anterior at the level of the lateral column. The brachial artery lies anterior to the joint and is at risk in anterior approaches, and the median nerve travels with it.

The AO/OTA system is the working language, and the letter tells you what the operation has to achieve. A is extra-articular and is plated without an osteotomy; B is partial articular, one column with its share of the joint; C is complete articular, the articular block separated from both columns, so the joint has to be rebuilt and then fixed stably to the shaft. Type C is the most common pattern requiring surgical reconstruction, and C3, comminuted at both the joint and the metaphysis, is the most complex.

History. Ask about:

• Mechanism (fall, direct trauma, high or low energy)
• Age and activity level
• Hand dominance
• Pre-injury function and comorbidities
• Occupation, which bears directly on whether a TEA could be considered

Examination. Gross swelling and deformity confirm the fracture; the rest of the examination is a search for the findings that change the plan.

The ulnar nerve before surgery. Pre-operative ulnar nerve injury occurs in 15-20% of distal humerus fractures. Document it carefully before surgery. Most are neurapraxias and recover; persistent or worsening symptoms may require exploration.

Neurovascular examination. Test and record each of the three nerves and the circulation:

• Ulnar nerve: sensation over the little finger, first dorsal interosseous strength, Froment's sign
• Radial nerve: wrist and finger extension, sensation over the dorsal first web
• Median nerve: sensation over the thumb and index, thenar strength
• Brachial artery pulse and capillary refill

Associated injuries.

• Ipsilateral forearm fractures (floating elbow)
• Olecranon fractures
• Proximal ulna fractures

Differential diagnosis. The painful, swollen elbow after trauma has a short list, and the radiograph separates most of it; the coronal shear fracture is often missed on plain films.

Radiographs. Two views, and each answers a different question:

• AP elbow: column involvement and the carrying angle
• Lateral elbow: anterior or posterior displacement and articular involvement
• Oblique views: may help delineate the fracture pattern

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Traction views. AP and lateral films taken with longitudinal traction reduce the overlap of the fragments and define the pattern better, which makes them useful for surgical planning.

CT with 3D reconstruction is essential for surgical planning in all Type C fractures. It defines the articular involvement, finds the small fragments and lets you plan the fixation. Do not operate without adequate imaging. Request it for:

• All intra-articular fractures (Type B and C)
• Surgical planning for ORIF
• Coronal shear fractures (capitellar/trochlear)
• Comminuted patterns

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MRI is rarely indicated acutely. It may be useful for soft-tissue assessment in delayed presentations.

Algorithm

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The decision. Virtually all displaced distal humerus fractures are treated operatively, to restore the anatomy and allow early mobilisation. The fracture type sets the operation; the patient sets whether that operation is fixation or replacement.

Operative indications.

• Virtually all displaced distal humerus fractures
• Any articular involvement (Type B, C)
• Open fractures
• Associated vascular injury
• Polytrauma with planned early mobilisation

Non-operative treatment. Conservative management has a very limited role in displaced fractures: the truly undisplaced fracture, the non-ambulatory patient, and the patient whose comorbidities preclude surgery. If it is chosen, splint at 90 degrees, start gentle motion early, and accept deformity and functional limitation, because it often results in stiffness and malunion.

"Bag of bones". This is deliberate non-operative management of a comminuted fracture: a brief period of immobilisation followed by early active motion, accepting that the elbow may heal as a malunion or as a painless, mobile fibrous pseudarthrosis, the "functional flail" elbow, rather than as an anatomically reduced joint. It is for the frail, very elderly, non-ambulatory or severely demented patient, or one medically unfit for the prolonged anaesthesia of a complex ORIF or TEA, in whom the morbidity of surgery outweighs the functional gain, especially if the arm is mainly a helper or is used with a frame or wheelchair.

The case for it is that it avoids the substantial wound, infection and hardware complications of operating on osteoporotic comminution in a fragile patient, and that surprisingly acceptable function and good pain relief are reported when early motion is allowed, because even a lax elbow can serve low demands. The price is reduced strength, some instability and deformity. It is a demand-matched compromise rather than a reconstruction, so reserve it for the genuinely high-risk patient and counsel accordingly; for the fit elderly patient with an unreconstructable joint, primary TEA remains the better functional option.

Timing. Operate within 24-48 hours if the soft tissues permit. The elbow tolerates delay poorly: swelling, stiffness and surgical difficulty all increase with time, and delay beyond 2-3 weeks increases the difficulty significantly.

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Staged surgery. Where the soft tissues will not take a definitive operation, a temporary external fixator holds the fracture while they recover, and reconstruction follows; it is appropriate for open or severely comminuted fractures. Stage for:

• Open fractures (Gustilo II, III)
• Severe soft-tissue injury
• Contaminated wounds
• Vascular injury requiring repair
• Polytrauma requiring damage control

Stiffness is the most common complication, at 15-50%. The functional arc for most activities of daily living is 30-130 degrees of flexion and 50 degrees of pronation-supination; that is the minimum acceptable outcome, and patients should be counselled that some stiffness is expected. Prevention is stable fixation that allows early motion, and continuous passive motion may help. Established stiffness is treated with physiotherapy, dynamic splinting, and arthroscopic or open release.

Ulnar neuropathy after surgery runs at 10-15%, and new symptoms may develop post-operatively. Most neurapraxias recover over 6-12 months. Persistent symptoms may require revision transposition.

Heterotopic ossification is more common with delayed surgery, head injury and severe trauma. Prophylaxis is indomethacin 75mg/day for 2 weeks or single-dose radiotherapy. Ossification that limits motion may need excision, after waiting 12 months or more.

Arthritis. An articular step of more than 2mm increases the risk of post-traumatic arthritis significantly, which is the reason for the emphasis on anatomic reduction.

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The principle. The goal is early motion to prevent stiffness, and stable fixation that allows early movement produces better outcomes than rigid immobilisation. If the fixation is not stable enough for motion, it is not adequate. The programme balances motion against healing, and often needs a long course of therapy.

Union. In the Edinburgh series 90.6% of fractures had united by 12 weeks, and about half of the remainder healed by 24 weeks without further surgery. The patterns that risk union problems are the "low" transcondylar fractures (A2.3, A3) and the simple intercondylar fracture (C1.3); the AO grade alone does not predict it.

What to expect by treatment.

What predicts it.

• Patient age and bone quality
• Fracture complexity (C3 worse than C1)
• Quality of reduction (articular step-off)
• Adequacy of fixation
• Associated injuries
• Compliance with rehabilitation

Global epidemiology (PubMed-backed):

The elderly, low-energy ("fragility") fracture is the fastest-growing subgroup worldwide as populations age, and these patients drive the ORIF-versus-TEA debate.

Guideline and consensus positions (side-by-side):

No single high-level society guideline mandates ORIF versus TEA; the McKee RCT (PMID 18823799) remains the anchor evidence and all guidance is consistent with selective primary TEA.

Registry evidence:

National joint registries (Norwegian Arthroplasty Register, AOANJRR, UK NJR) consistently show elbow arthroplasty durability below that of hip and knee replacement, which underpins the lifelong activity restriction and the avoidance of TEA in younger, higher-demand patients.

Practice variation:

• High-volume elbow/upper-limb units perform more primary TEA and more complex C3 reconstructions; smaller units more often transfer or default to ORIF.
• Parallel-plate use is more common in North American practice, perpendicular (90-90) in parts of Europe and Asia; functional outcomes are equivalent (TRON study, PMID 36527504), with the main difference being symptomatic hardware removal.
• In ageing health systems worldwide, the rising fragility-fracture burden is increasing demand for both ORIF and selective primary TEA; national registries including the AOANJRR track elbow arthroplasty outcomes.