Elbow Stiffness & Contracture (Post-traumatic Arthrofibrosis)

• Common after significant elbow trauma - intra-articular distal humerus and radial-head fractures, fracture-dislocations (terrible triad), and any injury treated with prolonged immobilisation.
• Highest-risk groups for heterotopic ossification: associated head injury, burns, high-energy/complex trauma, and delayed or repeated surgery.
• A spectrum of severity from a mild terminal-extension loss to a functionally fused elbow; the functional impact - not the absolute degrees - drives treatment.
• Largely preventable: the biggest determinant is how the original injury is managed (stable fixation enabling early motion vs prolonged immobilisation).

Morrey defined a functional arc of elbow motion — the range needed for most activities of daily living: roughly 30 to 130 degrees of flexion (a 100-degree arc) and 50 degrees each of pronation and supination. Most daily tasks fall within this range, so loss of motion within the functional arc — particularly terminal extension and flexion to reach the mouth/face — is what disables patients. Treatment aims to restore at least this functional arc.

The ulnar nerve is at risk both from the stiffness itself (a tight flexion contracture tethers it) and during release (and from the regained flexion afterwards). Decompress or transpose it for a severe flexion contracture (greater than ~90–100°) or pre-existing ulnar symptoms when operating.

• A highly congruent, three-joint articulation (ulnohumeral, radiocapitellar, proximal radioulnar) within a single capsule tolerates very little incongruity or capsular thickening before motion is lost.
• The brachialis lies directly on the anterior capsule - injury causes haematoma and then fibrosis/contracture of the anterior capsule, and is a substrate for anterior heterotopic ossification.
• Capsular response to injury: the capsule becomes thickened and fibrotic with disordered collagen and increased myofibroblasts, shortening across the joint - the extrinsic contracture.
• Heterotopic ossification forms when osteoprogenitor cells in injured soft tissue undergo aberrant ossification; risk is amplified by central nervous system injury, burns and high-energy trauma, and bridging HO can mechanically block motion.
• Intra-articular pathology (incongruity from malunion, loose bodies, osteophytes, chondral loss) adds an intrinsic block - and the two usually coexist (mixed), the intra-articular injury driving a secondary capsular contracture.

CT defines the bony causes and HO maturity - the single most useful investigation for planning. Excising immature HO (still active on imaging/bone scan) increases recurrence, so timing the release to HO maturity is central. Always pair imaging with the clinical end-feel to decide whether the limitation is capsular (extrinsic) or bony (intrinsic).

The single most effective strategy is prevention: achieve stable internal fixation of elbow injuries that allows early active motion, and avoid prolonged immobilisation (immobilise in extension rather than flexion if needed). The evidence also corrects two old myths — heterotopic ossification is not inevitably a bad prognostic feature, and passive mobilisation does not cause elbow stiffness. A supervised early-motion therapy programme after injury or surgery is central.

• Functional arc = 30–130° flexion (100° arc) + 50–50° pronation/supination — the treatment target.
• Morrey classification: extrinsic (capsule/ligament/HO), intrinsic (articular/loose bodies/arthritis), mixed (commonest post-trauma).
• Prevention is paramount: stable fixation + early motion; HO is not always a bad sign, and passive mobilisation does NOT cause stiffness.
• End-feel guides cause: soft = capsular (extrinsic), hard = bony/HO/malunion (intrinsic).
• Therapy/splinting first; then arthrolysis (open column/medial or arthroscopic) — release capsule, remove loose bodies, excise MATURE HO; protect the ulnar nerve.
• Outcomes ~50° gain but counsel re recurrence (~14% HO), ~10% complications, possible re-op.