Milch Classification of Lateral Condyle Fractures

The visible ossified fragment underestimates the real fracture in younger children because much of the lateral condyle and trochlea is cartilage. If the joint surface or hinge is uncertain on plain radiographs, use an internal oblique view and consider arthrogram, MRI, or intra-operative assessment.

The topic's complications are named — here is what examiners want you to DO about them:

• Established non-union with a viable, minimally-displaced fragment: the principle is in-situ fixation (a compression screw) plus bone grafting WITHOUT mobilising/dissecting the fragment — disturbing the posterior soft-tissue attachments to reduce the non-union risks osteonecrosis of the already-tenuous fragment. Accept a small malposition rather than devascularise it.
• Why fix a non-union at all: to halt the progressive cubitus valgus that follows (the un-tethered lateral physis keeps growing / the elbow drifts into valgus) and the resulting traction tardy (delayed) ulnar neuropathy.
• Established cubitus valgus + tardy ulnar nerve palsy: treat the nerve with anterior ulnar nerve transposition (decompress/relocate it out of the stretched cubital tunnel), and correct the deformity with a distal humeral (supracondylar) corrective osteotomy when the valgus/function warrants it.
• The whole cascade — displaced fracture cast in plaster → non-union → cubitus valgus → tardy ulnar palsy — is the classic "why you must not cast a displaced lateral condyle fracture" story.

Because Milch is anatomical and Jakob is dated, two modern displacement/articular-hinge systems now drive treatment and are increasingly the answer examiners want:

• Weiss classification (the practical, treatment-linked one): Type I — under 2 mm displacement → cast/immobilise; Type II — 2 mm or more with an INTACT articular cartilage hinge → closed reduction and percutaneous pinning (CRPP); Type III — 2 mm or more with a DISRUPTED articular surface → open reduction and internal fixation. Weiss also showed the complication rate rises with grade (notably higher in Type III).
• Song classification: a five-stage scheme grading the progression of the fracture gap on the internal oblique radiograph (from a small lateral-gap stage 1 through to a completely displaced, rotated stage 5) — useful for deciding which "minimally displaced" fractures are safe to observe versus pin.

The unifying message is unchanged from Milch/Jakob — the integrity of the articular (cartilage) hinge and the amount of displacement, assessed on the internal oblique view, decide cast vs CRPP vs ORIF — but Weiss/Song state it in directly operative terms.