When the Humeral Diaphysis Fails to Unite
- Humeral shaft nonunion is failure of the diaphysis to unite (no progressive healing, typically by around 6 months); the humeral shaft is relatively prone to nonunion with certain risk factors - TRANSVERSE fracture pattern, fracture DISTRACTION/gapping, proximal-third location, inadequate immobilisation, open fracture, infection, and patient factors (smoking, NSAIDs, obesity, diabetes, poor bone quality).
- Classify the nonunion: HYPERTROPHIC (abundant 'elephant-foot' callus that fails to bridge - a MECHANICAL/stability problem, with viable bone) versus ATROPHIC (tapered, sclerotic, avascular ends with a gap and little callus - a BIOLOGICAL problem) versus INFECTED.
- Always EXCLUDE INFECTION before treating (history, inflammatory markers, prior surgery), and document RADIAL NERVE function pre-operatively - the nerve is intimately related to the shaft and at risk both from the nonunion and during surgery.
- The GOLD-STANDARD treatment of aseptic humeral shaft nonunion is OPEN reduction with COMPRESSION PLATING (dynamic compression/locking plate) plus AUTOGENOUS (iliac crest) BONE GRAFT - this achieves UNION in the large majority (around 90-100% in series), restoring shoulder and elbow function.
- Unlike the femur and tibia, EXCHANGE NAILING is UNRELIABLE for humeral shaft nonunion; a failed nail is best converted to COMPRESSION PLATE FIXATION WITH BONE GRAFT rather than a larger nail.
- Atrophic and gap nonunions need the BIOLOGY addressed (autograft, and biological adjuncts such as BMP where appropriate); infected nonunions require infection ERADICATION (debridement, culture-directed antibiotics, sometimes staged reconstruction) alongside stabilisation - following the 'diamond concept' of stability + biology + a viable host.
- “Hypertrophic = stability problem (give compression); atrophic = biology problem (give compression PLUS bone graft).
- “In the HUMERUS, exchange nailing does NOT reliably achieve union - convert to compression plate + autograft.
- “Always exclude infection and check/protect the radial nerve before and during surgery.
Risk Factors & Patterns
Most humeral shaft fractures heal, whether treated non-operatively in a functional brace or operatively. Nonunion occurs with identifiable risks, and recognising them helps both prevention and the management plan.
- The fracture - a transverse pattern, distraction or gapping (over-distraction in a brace or by gravity, or soft-tissue interposition), a proximal-third location, comminution or bone loss, an open fracture, and infection
- The treatment - inadequate immobilisation or instability and, after surgery, inadequate fixation
- The patient - smoking, NSAIDs, diabetes, obesity, poor bone quality and other comorbidities
Classification & Assessment
The three types. The classification separates a mechanical problem from a biological one, and both from infection.
- Hypertrophic - exuberant 'elephant-foot' callus with no bridging. The biology is intact and the bone viable; the problem is mechanical, insufficient stability.
- Atrophic - tapered, avascular, sclerotic ends with a gap and little or no callus. The problem is biological, and often mechanical too.
- Infected (septic) - must be recognised, and the infection eradicated as part of the plan.
Assessment. Radiographs, with CT where needed, confirm the nonunion, characterise it as hypertrophic or atrophic, and assess the implant and any bone loss. Infection is excluded from the history (wound problems, previous surgery), CRP, ESR and FBC, and deep intra-operative cultures, as set out under Excluding Infection.
The radial nerve and the host. Document radial nerve function, and the rest of the neurovascular examination, before operating: the nerve is intimately related to the shaft and is at risk both from the nonunion and during surgery. Optimise the patient at the same time by stopping smoking, reviewing NSAIDs and correcting any metabolic or endocrine cause.
The diamond concept. Union needs mechanical stability, osteogenic cells, an osteoconductive scaffold, osteoinductive signals (growth factors) and an adequate vascular and host environment. It is the framework for deciding what each nonunion needs.
Management
The gold standard. For an aseptic humeral shaft nonunion it is open reduction and internal fixation with a compression plate (dynamic compression or locking), achieving direct compression across the nonunion, supplemented with autogenous iliac crest bone graft, especially for atrophic and gap nonunions. The combination addresses both stability and biology. It achieves union in the large majority of cases, around 90-100% in large series, with restoration of shoulder and elbow function.
Hypertrophic. The biology is fine, so provide rigid stability and compression with a compression plate. Bone graft is often not essential but may be added, and union is highly reliable once stability is restored.
Atrophic or gap. Add biology: thorough debridement of the avascular ends and autogenous iliac crest graft, considering biological adjuncts such as BMP for large or recalcitrant defects, and structural graft or bone-transport/Masquelet techniques for segmental loss.
Infected. Eradicate the infection by debridement, cultures and culture-directed antibiotics, often as a staged approach with debridement and an antibiotic cement spacer before reconstruction. Stabilise with a plate, or external fixation if needed, and graft once the infection is controlled.
For a femoral or tibial diaphyseal nonunion after nailing, exchange nailing with a larger reamed nail is often effective: it adds stability and reams in biology. In the humerus exchange nailing is unreliable. A failed humeral nail, or a nonunion, is best treated by conversion to compression plating with autogenous bone graft: remove the nail, freshen the nonunion, compress and plate, and graft.
Approach & Finding the Radial Nerve
The nerve's course. The radial nerve spirals around the humeral shaft and is intimately related to the mid and distal diaphysis, and to the nonunion and any callus. It crosses the posterior humerus in the spiral groove, with the profunda brachii vessels, in the middle third, then pierces the lateral intermuscular septum roughly a hand's breadth above the lateral epicondyle to enter the anterior compartment.
Anterolateral (brachialis-splitting) approach. This suits proximal- and mid-third nonunions and gives an anterior surface for plating. The nerve is at risk distally, where it pierces the lateral intermuscular septum.
Posterior (triceps-splitting, or paratricipital/triceps-sparing) approach. This is favoured for mid- and distal-third nonunions. It gives a broad, flat posterior surface for a long plate and lets you identify the nerve directly in the spiral groove.
Find the nerve in normal tissue away from the nonunion and trace it into the scar or callus. Never dissect blindly at the nonunion, where it may be encased in callus. If there is a pre-operative radial palsy, or the nerve is tethered in callus, formally explore and neurolyse it as part of the procedure.
The palsy to consent for. Post-operative radial-nerve palsy, usually transient, is the commonest neurological complication of humeral nonunion surgery, and the patient should be counselled about it. A nerve that is identified, mobilised and protected throughout reduces the risk.
The detailed course of the nerve is in Radial Nerve Anatomy, and reconstruction of an established palsy in Tendon Transfers for Radial Nerve Palsy; the point here is finding and protecting it during nonunion surgery.
The Construct: More Than 'a Plate'
"Compression plate" is the headline, but the construct is what delivers union.
A long, strong plate. A broad large-fragment (4.5 mm) dynamic-compression or locking plate spans well beyond the nonunion, with adequate fixation in each main fragment. Aim for at least three bicortical screws (six cortices) on each side, often more.
Absolute stability with interfragmentary compression. Compress a transverse or short-oblique nonunion through the plate in compression mode, or with a lag screw across an oblique one. That gives the rigid, gap-free environment a hypertrophic nonunion needs for primary (direct) bone healing.
When one plate is not enough. Dual or orthogonal plating, or a longer and stronger construct, is used for osteopenic bone, rotational instability, or when a single plate is insufficient. Locking screws improve fixation in osteoporotic bone.
Preparing the bed for the graft. The nonunion is freshened and decorticated, sclerotic or avascular bone and interposed tissue are removed, and the canal is reopened. The autograft is packed there, addressing biology while the construct delivers the mechanics.
Why "a plate" fails. Simply putting on a plate without compression, or with too short a construct, fails because the hypertrophic nonunion is a mechanical problem and needs genuine absolute stability. General plate biomechanics, such as working length and stress concentration, are covered in Bending Moment Distribution.
Afterwards: Rehabilitation and What to Expect
Union is not the end of the operation. The commonest residual complaint after a successfully united humeral nonunion is a stiff shoulder or elbow, and that is determined by what happens in the weeks after surgery.
Post-operative course after compression plating and grafting
A sling for comfort only, not for immobilisation: a construct that achieved absolute stability does not need protecting from gravity. Record radial nerve function on waking, since a new post-operative palsy needs to be distinguished from a pre-existing one. The iliac crest donor site is often the dominant early pain complaint; warn about this beforehand.
Immediate active-assisted shoulder and elbow motion within comfort: pendulum exercises, elbow flexion-extension and forearm rotation. The whole point of a rigid compression construct is that it permits early motion; nursing the arm in a sling for six weeks converts a united humerus into a stiff one.
Progress to active and then resisted exercise as pain allows. Avoid heavy lifting and torsional loading, since a rotational force is what breaks a humeral plate, until there is radiographic bridging. Serial radiographs at roughly 6, 12 and 24 weeks.
Union in reported series averages around 16 weeks (roughly 10 to 26). Failure of progression by this point should prompt reassessment for occult infection or a metabolic cause rather than simply waiting longer.
Expect a period of shoulder and elbow stiffness, donor-site discomfort that can persist for months, and a visible scar. Plate removal is not routine and carries its own radial nerve risk; reserve it for genuinely symptomatic hardware after union is secure.
Mnemonics & Memory Aids
UNITE
Hook:To UNITE a humeral nonunion: type it, protect the nerve, exclude infection, compression-plate + graft, don't re-nail.
DIAMOND
Hook:The DIAMOND concept applied: stability + biology + viable host - and plate, don't re-nail, the humerus.
PLATE
Hook:PLATE the humeral nonunion: prepare it, compress it, graft it - after culturing it - and mind the radial nerve.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A patient has a humeral shaft nonunion 8 months after a transverse mid-shaft fracture treated in a brace. How do you classify and assess it, and what is the gold-standard treatment?”
“How does your management differ for a hypertrophic versus an atrophic versus an infected humeral nonunion, and why is the humerus different from the femur?”
Risk factors
- Transverse pattern, distraction/gapping, proximal-third, open, infection, comminution
- Inadequate immobilisation/instability
- Smoking, NSAIDs, diabetes, obesity, poor bone quality
Classify & assess
- Hypertrophic (elephant-foot callus = stability problem) vs atrophic (tapered/avascular = biology) vs infected
- EXCLUDE infection (CRP/ESR, cultures); document RADIAL NERVE
- Diamond concept: stability + cells + scaffold + signals + viable host
Treatment
- Gold standard (aseptic): compression plate + autogenous iliac-crest bone graft (~90-100% union)
- Hypertrophic: compression often suffices; atrophic/gap: add graft (+/- BMP/structural/transport)
- Infected: eradicate infection (staged) + stabilise + graft
Key pitfalls
- Exchange nailing UNRELIABLE in the humerus - convert to compression plate + graft
- Radial nerve at risk (commonest neuro complication) - protect it
- Don't reconstruct over unrecognised infection
Evidence & Key Studies
Treatment of nonunion of humeral shaft fracture with dynamic compression plate and cancellous bone graft
- In 105 humeral shaft nonunions (67 atrophic, 20 hypertrophic) treated with a dynamic compression plate plus cancellous bone graft, ALL united, at an average of 16 weeks (range 10-26).
- Complications were limited to 4 temporary radial-nerve palsies and 3 wound infections; shoulder and elbow function were satisfactory at follow-up.
- Compression plating with supplemental cancellous bone graft is a reliable, effective treatment for humeral shaft nonunion.
Repair of humeral shaft nonunion with plate and screw fixation and iliac crest bone graft
- Describes the technique for humeral shaft nonunion repair: nonunion-site preparation, direct compression of the fracture using plate osteosynthesis, and iliac crest bone graft harvest/utilisation.
- Reinforces compression plating with autogenous bone graft as the management approach for humeral shaft nonunion.
- Emphasises freshening the nonunion and achieving direct compression across the site.
Metabolic and endocrine abnormalities in patients with nonunions
- 37 patients selected from 683 consecutive nonunions by three criteria - an unexplained nonunion despite adequate reduction and fixation, multiple low-energy fractures with at least one nonunion, or nonunion of a non-displaced pubic ramus or sacral ala fracture - were referred for endocrine evaluation.
- 31 of 37 (84%) had at least one NEW metabolic or endocrine diagnosis; vitamin D deficiency was commonest at 25 of 37 (68%), with calcium imbalance, central hypogonadism, and thyroid and parathyroid disorders also found.
- Eight patients achieved union with medical treatment alone and no further surgery, at a mean of 7.6 months after seeing the endocrinologist.
Plate fixation of ununited humeral shaft fractures: effect of type of bone graft on healing
- Consecutive single-surgeon cohort, one strict protocol, two eras: 45 atrophic/delayed nonunions plated with autologous iliac crest graft (1992-1999) versus 33 with demineralised bone matrix (2000-2003).
- Union after the index surgery: 100% (45/45) with autograft versus 97% (32/33) with DBM; mean time to union 4.5 versus 4.2 months - a wash on healing.
- The difference was at the donor site: 20 of 45 autograft patients (44%) had donor-site morbidity, mostly prolonged pain, including one superficial infection needing irrigation and debridement.
Proximal humerus and humeral shaft nonunions
- Estimated nonunion rate after closed treatment: 1.1-10% for proximal humerus fractures and 5.5% for humeral shaft fractures.
- Operative treatment is indicated when serial radiographs at least 6-8 weeks apart show no progressive healing.
- For humeral shaft nonunion, ORIF with compression plating and bone graft remains the standard of care, with a greater than 90% union rate and good functional outcomes; locked plates, dual plating and cortical strut allografts serve the osteopenic host.
The high union rates and complication profile of compression plating plus cancellous bone graft come from the cited Hsu series, and the technique (nonunion preparation, direct compression, iliac-crest autograft) from the cited Egol-group description. The hypertrophic/atrophic classification, the diamond concept, and the unreliability of exchange nailing in the humerus are standard, well-established teaching, as are the infection work-up specifics and the post-operative course. The metabolic and endocrine screening criteria, the 84% and 68% figures and the eight patients who united medically come from the cited Brinker series. The autograft-versus-DBM comparison and the 44% donor-site morbidity figure come from the cited Hierholzer cohort, and the background nonunion rates and greater-than-90% union benchmark from the cited Cadet review. (See also Nonunion Management, Humeral Shaft Fractures, Proximal Humerus Nonunion and Bone Grafts.)